Professor Megh Mallavarapu
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2024 Li H, Wang Z, Feng B, Shi J, Liao M, He K, et al., 'Arsenic stress on soil microbial nutrient metabolism interpreted by microbial utilization of dissolved organic carbon', Journal of Hazardous Materials, 470 (2024) [C1]

In a 120-day microcosm incubation experiment, we investigated the impact of arsenic contamination on soil microbial nutrient metabolism, focusing on carbon cycling processes. Our ... [more]

In a 120-day microcosm incubation experiment, we investigated the impact of arsenic contamination on soil microbial nutrient metabolism, focusing on carbon cycling processes. Our study encompassed soil basal respiration, key enzyme activities (particularly, ß-1,4-N-acetylglucosaminidase and phosphatases), microbial biomass, and community structure. Results revealed a substantial increase (1.21¿2.81 times) in ß-1,4-N-acetylglucosaminidase activities under arsenic stress, accompanied by a significant decrease (9.86%-45.20%) in phosphatase activities (sum of acid and alkaline phosphatases). Enzymatic stoichiometry analysis demonstrated the mitigation of microbial C and P requirements in response to arsenic stress. The addition of C-sources alleviated microbial C requirements but exacerbated P requirements, with the interference amplitude increasing with the complexity of the C-source. Network analysis unveiled altered microbial nutrient requirements and an increased resistance process of microbes under arsenic stress. Microbial carbon use efficiency (CUE) and basal respiration significantly increased (1.17¿1.59 and 1.18¿3.56 times, respectively) under heavy arsenic stress (500 mg kg-1). Arsenic stress influenced the relative abundances of microbial taxa, with Gemmatimonadota increasing (5.5¿50.5%) and Bacteroidota/ Nitrospirota decreasing (31.4¿47.9% and 31.2¿63.7%). Application of C-sources enhanced microbial resistance to arsenic, promoting cohesion among microorganisms. These findings deepen our understanding of microbial nutrient dynamics in arsenic-contaminated areas, which is crucial for developing enzyme-based toxicity assessment systems for soil arsenic contamination.

Nova 2024 Praveen K, Abinandan S, Venkateswarlu K, Megharaj M, 'Emergy Analysis and Life Cycle Assessment for Evaluating the Sustainability of Solar-Integrated Ecotechnologies in Winery Wastewater Treatment', ACS Sustainable Chemistry and Engineering, 12 4676-4689 (2024) [C1]

Innovative approaches in sustainable wastewater management are vital in addressing climate change. This study introduces a novel assessment of solar-integrated ecotechnologies, fo... [more]

Innovative approaches in sustainable wastewater management are vital in addressing climate change. This study introduces a novel assessment of solar-integrated ecotechnologies, focusing on the constructed wetland (CW) and microalgae-based systems, viz., high-rate algal pond (HRAP) and photobioreactor (PBR), for the treatment of winery wastewater. Utilizing Emergy analysis and life cycle assessment (LCA), we comprehensively compared these technologies in terms of environmental impact, resource recovery efficiency, and circular economy integration. Our Emergy analysis of the HRAP revealed a substantial reliance on renewable inputs (94%) and its lower nonrenewable resource consumption compared to the CW system. The Emergy sustainability index initially indicated a preference for the CW system (42.93 sej year-1; sej = solar emjoule), but deeper analysis showed greater sustainability in the HRAP (341 sej year-1) and PBR (118 sej year-1). LCA results further revealed that PBR systems had a significant land-use footprint, impacting other environmental indices such as photochemical ozone formation and freshwater eutrophication. Additionally, the HRAP and PBR demonstrated a marked reduction in greenhouse gas emissions (-24800 and -23700 kg of CO2-eq, respectively) compared to the CW system (320 kg of CO2-eq). Life cycle cost analysis underscored the economic viability of these systems, with Scenario 3 (PBR) emerging as the most economically sustainable, exhibiting the highest internal rate of return (IRR) at 21.11% and a positive net present value after 20 years. Conversely, Scenario 1 (CW system), with its significant initial investment of AU$741220, showed no IRR due to the absence of revenue generation. Importantly, our study introduces circularity index scores as a novel element, revealing that the HRAP and PBR effectively incorporate circularity measures across various impact categories. These measures had moderate impacts, as indicated by scores close to but not exceeding 0.10, whereas the CW system showed no significant improvement, highlighting the need for more robust circularity strategies. Overall, our integrated framework provides a holistic view of the environmental impact and economic aspects, emphasizing the potential of solar-integrated microalgal systems in promoting circular (bio)economy practices and sustainable environmental management in the viticulture sector.

Nova 2024 Shabir R, Li Y, Megharaj M, Chen C, 'Pyrolysis temperature affects biochar suitability as an alternative rhizobial carrier', Biology and Fertility of Soils, 60 681-697 (2024) [C1]

Biochars produced from different feedstocks and at different pyrolysis temperatures may have various chemical and physical properties, affecting their potential use as alternative... [more]

Biochars produced from different feedstocks and at different pyrolysis temperatures may have various chemical and physical properties, affecting their potential use as alternative microbial carrier materials. In this study, biochars were produced from pine wood and oak feedstocks at various temperatures (400°C, 500°C, 600°C, 700°C and 800°C), characterized, and assessed for their potential as carriers for Bradyrhizobium japonicum (CB1809) strain. The biochars were then stored at two different storage temperatures (28°C and 38°C) for up to 90 days. Furthermore, the study also explored the role of potentially ideal carriers as inoculants in the growth of Glycine max L. (soybean) under different moisture levels i.e., 55% water holding capacity (WHC) (D0), 30% WHC (D1) and, 15% WHC (D2) using a mixture of 50% garden soil and 50% sand. The results were compared to a control group (without inoculants) and a peat inoculant. Among all the materials derived from pine wood and oak, pine wood biochar pyrolyzed at 400¿ (P-BC400) exhibited the highest CFU count, with values of 10.34 and 9.74 Log 10 CFU g- 1 after 90 days of storage at 28¿ and 38¿, respectively. This was notably higher compared to other biochars and peat carriers. Significant (p < 0.05) increases in plant properties: shoot and root dry biomass (174% and 367%), shoot and root length (89% and 85%), number of leaves (71%), membrane stability index (27%), relative water content (26%), and total chlorophyll (140%) were observed in plants treated with P-BC400 carrier inoculant compared to the control at D2; however, lower enrichment of d13C (37%) and d15N (108%) with highest number of root nodules (8.3 ± 1.26) and nitrogenase activity (0.869 ± 0.04) were observed under D2, as evident through PCA analysis, showing more nitrogen (N) fixation and photosynthetic activity. Overall, this experiment concluded that biochar pyrolyzed at lower temperatures, especially P-BC400, was the most suitable candidate for rhizobial inoculum and promoted soybean growth.

Nova 2024 Kuppusamy S, Venkateswarlu K, Megharaj M, Lee YB, 'Risks of veterinary antibiotics contamination in Indian organic farmlands: A reality unfolded', Environmental Advances, 15 (2024) [C1]

Globally, the widespread use of antibiotics in intensive animal farming has contributed to their increased environmental burden. Notably, data and knowledge on these contaminants ... [more]

Globally, the widespread use of antibiotics in intensive animal farming has contributed to their increased environmental burden. Notably, data and knowledge on these contaminants in farmlands are lacking in India, despite being a major agricultural producer worldwide. To date, no studies have explored whether antibiotics are an intractable environmental issue in Indian agroecosystems. Specifically, information on the prevalence and spread of common antibiotics in long-term animal manure-laden organic farmlands of India is non-existent. Here, we examined samples of manure, soil and vegetables collected from 24 different organic farmlands in India to assess the presence of residues from 15 typical veterinary antibiotics (VAs). Our findings revealed that nine VAs, including three tetracyclines (TCs), three sulfonamides (SAs), one macrolide (ML), and two quinolones (QNs), were recorded in almost all the manure and soil samples. The residual levels of antibiotics (µg kg¿1) decreased in the following order: TCs (manure: 22.10¿161.10; soil: 8.30¿61) > SAs (manure: 0.90¿73; soil: 0.20¿48.40) > QNs (manure: nd¿3.60; soil: nd¿1.80) > MLs (manure: nd¿1.50; soil: nd¿0.90). Poultry manure-applied farmlands exhibited the highest antibiotic contamination levels, with total antibiotic concentrations surpassing the ecotoxicological effect trigger value of 100 µg kg-1 set by the Steering Committee of the Veterinary International Committee on Harmonization, highlighting the potential hazard of VAs to the soil ecosystem. The translocation of VAs in vegetables was in the order: leaf > root > fruit, and bioaccumulation of 0.10¿3.90 µg kg-1 was recorded. Notably, the calculated risk quotients of antibiotics in vegetables were ¿1, indicating the negligible risk to human health. Overall, our study unveils a concerning state of VAs pollution in organic farmlands in India that warrants special attention, as it may contribute to the proliferation of antibiotic resistance.

Nova 2024 Parven A, Md Meftaul I, Venkateswarlu K, Gopalan S, Megharaj M, 'Pre-emergence herbicides widely used in urban and farmland soils: fate, and potential human and environmental health risks', Environmental Geochemistry and Health, 46 (2024) [C1]

We determined the distribution, fate, and health hazards of dimethenamid-P, metazachlor, and pyroxasulfone, the effective pre-emergence herbicides widely used both in urban and ag... [more]

We determined the distribution, fate, and health hazards of dimethenamid-P, metazachlor, and pyroxasulfone, the effective pre-emergence herbicides widely used both in urban and agricultural settings globally. The rate-determining phase of sorption kinetics of these herbicides in five soils followed a pseudo-second-order model. Freundlich isotherm model indicated that the herbicides primarily partition into heterogeneous surface sites on clay minerals and organic matter (OM) and diffuse into soil micropores. Principal component analysis revealed that soil OM (R2, 0.47), sand (R2, 0.56), and Al oxides (R2, 0.33) positively correlated with the herbicide distribution coefficient (Kd), whereas clay (R2, ¿ 0.43), silt (R2, ¿ 0.51), Fe oxides (R2, ¿ 0.02), alkaline pH (R2, ¿ 0.57), and EC (R2, ¿ 0.03) showed a negative correlation with the Kd values. Decomposed OM rich in C=O and C¿H functional groups enhanced herbicide sorption, while undecomposed/partially-decomposed OM facilitated desorption process. Also, the absence of hysteresis (H, 0.27¿0.88) indicated the enhanced propensity of herbicide desorption in soils. Leachability index (LIX, < 0.02¿0.64) and groundwater ubiquity score (GUS, 0.02¿3.59) for the soils suggested low to moderate leaching potential of the herbicides to waterbodies, indicating their impact on water quality, nontarget organisms, and food safety. Hazard quotient and hazard index data for human adults and adolescents suggested that exposure to soils contaminated with herbicides via dermal contact, ingestion, and inhalation poses minimal to no non-carcinogenic risks. These insights can assist farmers in judicious use of herbicides and help the concerned regulatory authorities in monitoring the safety of human and environmental health. Graphical abstract: (Figure presented.)

Nova 2024 Ahuja V, Chauhan S, Purewal SS, Mehariya S, Patel AK, Kumar G, et al., 'Microbial alchemy: upcycling of brewery spent grains into high-value products through fermentation.', Crit Rev Biotechnol, 1-19 (2024) [C1] 2024 Afrin S, Alam MK, Ahmed MW, Parven A, Jubayer MF, Megharaj M, et al., 'Determination and probabilistic health risk assessment of heavy metals in widely consumed market basket fruits from Dhaka city Bangladesh', INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY, [C1] Nova 2024 Shabir R, Li Y, Megharaj M, Chen C, 'Biopolymer as an additive for effective biochar-based rhizobial inoculant.', Sci Total Environ, 912 169263 (2024) [C1] Nova 2024 Dhar K, Venkateswarlu K, Megharaj M, 'Enrichment of Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Strictly Anaerobic Sulfate-Reducing Cultures from Contaminated Soil and Sediment', CURRENT PROTOCOLS, 4 (2024) 2024 Praveen K, Abinandan S, Venkateswarlu K, Megharaj M, 'Harnessing Extremophilic Trait and Metabolic Flexibility of Microalgal Strains for the Treatment of Highly Alkaline Winery Wastewater', ACS ES and T Engineering, 4 455-465 (2024) [C1]

Microalgae possess traits that make them thrive under extreme environmental conditions, and this fascinating adaptability recognizes them as novel candidates for wastewater treatm... [more]

Microalgae possess traits that make them thrive under extreme environmental conditions, and this fascinating adaptability recognizes them as novel candidates for wastewater treatment and bioresource management. In this study, we assessed two extremophilic (acid-tolerant) microalgal strains, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, for their ability to thrive in high-alkaline environments as existing in winery wastewater. These strains showed a rapid growth rate (1.10-1.30 d-1), a substantial increase in chlorophyll, and efficient removal of carbon (70-80%) as well as nitrogen and phosphate (80-90%) during mixotrophic cultivation in highly alkaline winery wastewater. Metabolic analysis unveiled the interplay among CO2 fixation, nitrogen assimilation, amino acid metabolism, and other key pathways, highlighting the ability of the microalgal strains to change their metabolic processes in response to extreme-pH conditions. Especially noteworthy is the elevated expression of organic acids in strain MAS1, suggesting their vital role in nutrient uptake in the alkaline environment. Harnessing these extremophilic traits negates the need for wastewater pretreatment and reduces both energy and chemical footprints, aligning with several UN Sustainable Development Goals. Our study thus presents new insights into the extremophilic nature of microalgal strains for remediation, biomass production, and broader biotechnological applications, paving the way for sustainable industrial innovations.

Nova 2024 Adeleye AT, Bahar MM, Megharaj M, Fang C, Rahman MM, 'The Unseen Threat of the Synergistic Effects of Microplastics and Heavy Metals in Aquatic Environments: A Critical Review', Current Pollution Reports, 10 478-497 (2024) [C1]

Purpose of Review: The synergistic effects of microplastics (MPs) and heavy metals are becoming major threats to aquatic life and human well-being. Therefore, understanding synerg... [more]

Purpose of Review: The synergistic effects of microplastics (MPs) and heavy metals are becoming major threats to aquatic life and human well-being. Therefore, understanding synergistic interactions between MPs and heavy metals is crucial to comprehend their environmental impacts. Recent Findings: The mechanisms such as electrostatic attraction, surface interactions, ion exchange, hydrogen bonding, hydrophobic forces, and p¿p interactions behind the synergistic effects of MPs and heavy metals were critically reviewed and justified. In addition, the roles of surface chemistry in these interactions were also emphasized. Finally, efficient remediation techniques aligning with a circular economy-based initiative to promote sustainable solutions were recommended to mitigate plastic-heavy metal pollution to achieve a cleaner environment. Summary: This review examines the combined impact of MPs and heavy metals in aquatic ecosystems, detailing their mechanistic interactions, and consequences with proposed sustainable solutions. Additionally, this review highlights the MP-heavy metal contamination risks and emphasizes the need for further research to safeguard aquatic life and human health.

2024 Patel S, Halder P, Hakeem IG, Selezneva E, Jena MK, Veluswamy G, et al., 'The Fate of Fluorine Post Per- and Polyfluoroalkyl Substances Destruction during the Thermal Treatment of Biosolids: A Thermodynamic Study', Energies, 17 3476-3476 2024 Praveen K, Abinandan S, Venkateswarlu K, Megharaj M, 'Leveraging Phenotypic Traits in Microalgae: A Novel Strategy for Wastewater Treatment and Sustainable Biomass Production', ACS ES&amp;T Water, 4 103-113 (2024) [C1] Nova 2024 Gao T, Tian H, Niu H, Megharaj M, He W, 'Evaluation of arsenic pollution in field-contaminated soil at the soil's actual pH', JOURNAL OF ENVIRONMENTAL SCIENCES, 144 137-147 (2024) [C1] Nova 2024 Huang H, Tian H, Li Y, Wang Z, Yang T, Qian R, et al., 'Soil urease functional stability to Hg pollution: An ecotoxicological perspective', Ecotoxicology, (2024) [C1]

Mercury (Hg) is a persistent soil pollutant, and its toxicity can be evaluated using soil enzyme indicators. However, a thorough understanding of how the enzyme resists and remain... [more]

Mercury (Hg) is a persistent soil pollutant, and its toxicity can be evaluated using soil enzyme indicators. However, a thorough understanding of how the enzyme resists and remains resilient to Hg stress is essential, as it significantly impacts the accuracy of toxicity assessments. Therefore, it is worthwhile to understand the functional stability of urease in soil under Hg pollution. This study compares the effects of Hg at different concentrations and exposure times on soil urease. Results indicate that soil urease activity was enhanced in the first two hours under low levels of Hg pollution, decreased after six hours of acute Hg pollution, and reached its maximum reduction in 24 hours. The urease in fluvo-aquic soil, with higher soil organic matter showed higher resistance to Hg acute pollution than that in red soil. Over a longer aging process, soil urease activity gradually recovered with time. Hormesis effects were observed in red soil under high Hg stress after 30 days, showing the strong resilience of urease enzyme function to Hg pollution. The ecological dose, ED10, (the Hg concentration causing a 10% reduction in soil urease activity) ranged from 0.09 to 0.59 mg kg-1 under short-term exposure, and was lower than that under a longer aging process (0.28 to 2.71 mg kg-1). Further, aging reduced the Hg ecotoxicity due to decreased Hg availability and the resilience of soil urease activity. This indicates that the risk of Hg pollution estimated by soil urease as an indicator depends on exposure time and enzyme stability. These factors need consideration in heavy metal pollution assessments using soil enzymes.

2024 Khoshyan A, Luo Y, Nolan A, Megharaj M, Naidu R, Fang C, 'Degradation of per- and poly-fluoroalkyl substances (PFAS) using ultrasonication: Effect of reactor materials', Journal of Water Process Engineering, 63 (2024) [C1]

This study explores the impact of different reactor/container materials, such as glass and plastic, on the degradation of per- and poly-fluoroalkyl substances (PFAS) using indirec... [more]

This study explores the impact of different reactor/container materials, such as glass and plastic, on the degradation of per- and poly-fluoroalkyl substances (PFAS) using indirect ultrasonication in aquatic media. After subjecting the system to ultrasonication at 130 kHz with a 100 % effective power for 3.0 h, approximately 95 % and 46 % defluorination of perfluorooctanoic acid (PFOA) were achieved in a glass reactor and a polypropylene (PP) reactor, respectively. Under optimal conditions, calorimetry power at the highest applied power averaged 51 ± 0.7 W/L for glass and 55.1 ± 1 W/L for PP. A similar trend was observed for the defluorination of perfluorooctane sulfonic acid (PFOS), 1H, 1H, 2H, 2H-perfluorooctanesulfonic acid (6:2 FTS), and aqueous film-forming foam (AFFF) containing a complex mixture of PFAS, indicating that the glass reactor exhibited higher efficiency in ultrasonic irradiation transportation. The kinetics of PFOA degradation also revealed that a glass beaker facilitated faster removal than PP. The reaction mechanism suggested that the primary pathway involved a pyrolytic reaction, while free radicals also played a contributing role. The effect of free radicals, especially hydroxyl radicals ([rad]OH) was approved by potassium iodide (KI) dosimetry as well as reaction between [rad]OH with benzoic acid (BA) as a radical scavenger. Overall, the findings unambiguously demonstrate how the reactor material affects the indirect ultrasonication of PFAS in an aqueous environment.

Nova 2024 Kuppusamy S, Venkateswarlu K, Megharaj M, 'Tetracycline and fluoroquinolone antibiotics contamination in agricultural soils fertilized long-term with chicken litter: Trends and ravages', Science of the Total Environment, 946 (2024) [C1]

We investigated the potential accumulation of tetracyclines (TCs) such as chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DC), and fluoroquinolones (FQs) like enro... [more]

We investigated the potential accumulation of tetracyclines (TCs) such as chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DC), and fluoroquinolones (FQs) like enrofloxacin (ENR) and ciprofloxacin (CIP) in chicken litter and agricultural soils fertilized over short-term to long-term (<1¿30 yrs) with chicken litter in a poultry hub for the first time from Tamil Nadu, India. CTC, OTC, DC, CIP, and ENR were detected in 46¿92 % of the selected chicken litter samples, with mean levels ranging from 2.90 to 23.30 µg kg-1. Higher concentrations of TCs and FQs were observed in freshly collected chicken litter from poultry sheds than in those stockpiled in cultivated lands. CTC was the prevalent antibiotic in chicken litter. The overall occurrence, as well as the ecological risks of TCs and FQs, changed over a 30-yr period. The accumulation of veterinary antibiotics (VAs) (in µg kg-1) in short-term (>1 yr) to medium-term (1¿3 yrs) chicken litter-fertilized soils reached a maximum of 11.60 for CTC, 6.50 for OTC, 0.80 for DC, 3.70 for CIP, and 3.60 for ENR, but decreased in long-term (10¿30 yrs) fertilized soils. Ecological risk assessment revealed a Risk Quotient (RQ) of =0.10 for CTC, OTC, and DC in all soils, while an average risk (RQ >0.10¿<1.0) was evident with CIP and ENR in short-term and medium-term fertilized soils. Antibiotic resistance genes (ARGs), including tetA, tetB, qnrA, qnrB and qnrS were detected in most of the chicken litter samples and litter-fertilized soils. Thus, it is critical to develop and adopt effective mitigation strategies before applying chicken litter in farmlands to decrease VAs and ARGs, reducing their associated risks to public health and ecosystems in India considering ¿One Health¿ approach. Future investigations on the occurrence of other VAs and ARGs in soils fertilized with poultry litter at regional scale are required for effective risk mitigation of the widely used VAs.

Nova 2024 Hakeem IG, Halder P, Patel S, Selezneva E, Rathnayake N, Marzbali MH, et al., 'Current understanding on the transformation and fate of per- and polyfluoroalkyl substances before, during, and after thermal treatment of biosolids', Chemical Engineering Journal, 493 (2024) [C1]

Biosolids (stabilised sewage sludge) are the final solid residues of the wastewater treatment process and are generally applied on agricultural land in many countries, including A... [more]

Biosolids (stabilised sewage sludge) are the final solid residues of the wastewater treatment process and are generally applied on agricultural land in many countries, including Australia. Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic fluorinated chemicals with ubiquitous applications in consumer products and persist in the environment. Globally, PFAS have been detected in biosolids and are considered a source of PFAS discharge to the environment. The thermal treatment of biosolids is gaining increasing interest in the water sector. Therefore, the viability of thermal techniques for the safe destruction of PFAS has received substantial research attention in the last few years. Recent studies suggest that PFAS in biosolids can be removed and potentially destroyed during combustive (such as incineration) and non-combustive thermal treatment, such as pyrolysis, gasification, and hydrothermal carbonisation/liquefaction. However, there is limited understanding on the fate and transformation of PFAS degradation products across the overall thermal treatment process from biosolids feed pre-treatment to the gas cleaning (post-thermal treatment) stage. This review consolidates the current knowledge on PFAS transformation, destruction, and final fate before, during, and after thermal treatment of biosolids, covering lab, pilot scale, and industrial studies. It is suggested that PFAS degradation mechanisms during thermal treatment of biosolids may differ from the established pathways for pure PFAS salts, given that biosolids have a complex organic and inorganic matrix and typically have low PFAS concentrations. Among all thermal treatment techniques, pyrolysis has received extensive investigations at different scales of operation. However, for all techniques, treatment temperatures and residence time need to be sufficiently optimised for designing realistic large-scale thermal systems relevant to biosolids¿ compositional peculiarities for PFAS destruction.

Nova 2024 Sivaram AK, Mukunthan K, Megharaj M, 'Effects of pyroligneous acid on acute, chronic, and cyto-genotoxicity to earthworms ( Nova 2024 Voigt RAL, Alam MR, Stein TJ, Rahman MM, Megharaj M, MacFarlane GR, 'Uptake and distribution of metal(loid)s in two rare species of saltmarsh, blackseed samphire, Tecticornia pergranulata, and narrow-leafed wilsonia, Wilsonia backhousei, in New South Wales, Australia.', Mar Pollut Bull, 200 116058 (2024) [C1] Nova 2024 Praveen K, Abinandan S, Venkateswarlu K, Megharaj M, 'Synergy of eco-innovation with on-farm practices enhances circularity beyond conventional nutrient recovery framework', Resources, Conservation and Recycling, 208 (2024) [C1]

The escalating challenges of resource scarcity and environmental degradation in agroecosystems necessitate innovative strategies for sustainable nutrient management. This review e... [more]

The escalating challenges of resource scarcity and environmental degradation in agroecosystems necessitate innovative strategies for sustainable nutrient management. This review explores the integration of circular economy principles into nutrient recovery frameworks, emphasizing eco-innovative technologies that promote sustainability and resilience in agricultural practices. By examining various on-farm circularity practices and their efficacy in nutrient recovery, we highlight the potential of nature-inspired solutions such as constructed wetlands and algae-based systems to reduce environmental impacts and enhance nutrient use efficiency. The findings advocate for a paradigm shift towards advanced nutrient management strategies that leverage eco-innovation to reduce greenhouse gas emissions, optimize resource use, and align with global sustainability goals. The adoption of these strategies can significantly contribute to the sustainable transformation of the agricultural sector.

Nova 2024 Parven A, Meftaul IM, Venkateswarlu K, Megharaj M, 'Herbicides in modern sustainable agriculture: environmental fate, ecological implications, and human health concerns', International Journal of Environmental Science and Technology, (2024) [C1]

Herbicides play a crucial role in modern agriculture by controlling weeds and ensuring sustainable crop productivity. However, the use of herbicides has raised concerns regarding ... [more]

Herbicides play a crucial role in modern agriculture by controlling weeds and ensuring sustainable crop productivity. However, the use of herbicides has raised concerns regarding their contamination, posing serious threat to the environment, biodiversity, and food safety. Recent trends indicate a decline in the overall volume of herbicides usage, suggesting a shift towards more specific and targeted formulations of herbicides. Also, there has been an increased use of systemic and pre-emergence herbicides. The global agriculture still faces several challenges because of the adverse environmental impacts caused by herbicide contamination, both at the application site and offsite. In view of the growing concern, it is necessary to develop new herbicides with greater selectivity or bio-based herbicide that can degrade after successful control of the intended weed population and minimize or eliminate the environmental hazards. Furthermore, the adoption of integrated weed management practices rather than prolonged and repeated use of herbicide in agriculture can effectively reduce the growth of herbicide-resistant weed populations. The present review is a single valuable resource, providing insights into the recent trends and future challenges associated with herbicide use in modern agriculture, with a focus on human health and food safety. Also, we emphasize the advancements in herbicide technology, emergence of new herbicide-resistant weed species, regulatory considerations, and alternative approaches in herbicide use, all of which are particularly valuable to agroecology, policymakers, and stakeholders. Graphical Abstract: (Figure presented.)

2023 Meftaul IM, Venkateswarlu K, Annamalai P, Parven A, Megharaj M, 'Degradation of four pesticides in five urban landscape soils: human and environmental health risk assessment', Environmental Geochemistry and Health, 45 1599-1614 (2023) [C1]

Pesticides are the most cost-effective means of pest control; however, the serious concern is about the non-target effects due to their extensive and intensive use in both agricul... [more]

Pesticides are the most cost-effective means of pest control; however, the serious concern is about the non-target effects due to their extensive and intensive use in both agricultural and non-agricultural settings. The degradation rate constant (k) and half-life (DT50) of four commonly used pesticides, glyphosate, 2,4-D, chlorothalonil and dimethoate were determined in five Australian urban landscape soils, with varying physicochemical characteristics, to assess their environmental and human health risks. The k values (day-1) for the selected pesticides were inversely proportional to those of organic carbon (OC), silt, clay and Fe and Al oxides, and directly proportional to pH and sand content in soils. In contrast, the calculated values of DT50 (days) of all the four pesticides in five soils positively correlated with OC, clay, silt and oxides of Fe and Al, whereas soil pH and sand content exhibited a negative correlation. The calculated values of environmental indices, GUS and LIX, for the selected pesticides indicate their potential portability into water bodies, affecting non-target organisms as well as food safety. The evaluation for human non-cancer risk of these pesticides, based on the calculated values of hazard quotient¿(HQ) and hazard index¿(HI), suggested that exposure of adults and children to soils, contaminated with 50% of initially applied concentrations, through ingestion, dermal and inhalation pathways might cause negligible to zero non-carcinogenic risks. The present data might help the stakeholders in applying recommended doses of pesticides in urban landscapes and regulatory bodies concerned in monitoring the overall environmental quality and implementing safeguard policies. Our study also clearly demonstrates the need for developing improved formulations and spraying technologies for pesticides to minimize human and environmental health risks. Graphic abstract: [Figure not available: see fulltext.]

Nova 2023 Ramakrishnan B, Maddela NR, Venkateswarlu K, Megharaj M, 'Potential of microalgae and cyanobacteria to improve soil health and agricultural productivity: a critical view', Environmental Science: Advances, 2 586-611 [C1] Nova 2023 Adeleye AT, Bahar MM, Megharaj M, Rahman MM, 'Recent developments and mechanistic insights on adsorption technology for micro- and nanoplastics removal in aquatic environments', Journal of Water Process Engineering, 53 103777-103777 (2023) [C1] Nova 2023 Tao K, Tian H, Wang Z, Shang X, Fan J, Megharaj M, et al., 'Ecotoxicity of parathion during its dissipation mirrored by soil enzyme activity, microbial biomass and basal respiration.', Chemosphere, 311 137116 (2023) [C1] Nova 2023 Gao T, Tian H, Wang Z, Shi J, Yang R, Wang F, et al., 'Effects of atrazine on microbial metabolic limitations in black soils: Evidence from enzyme stoichiometry.', Chemosphere, 334 139045 (2023) [C1] Nova 2023 Li Y, Shabir R, Rashti MR, Megharaj M, Chen C, 'Cow manure compost-based products as alternative rhizobial carrier materials', Land Degradation &amp; Development, 34 4768-4780 (2023) [C1] Nova 2023 Fang L-R, Yang X-C, Wu C-Y, Sun K, Megharaj M, He W, 'Endophytic Nova 2023 Das AP, Mallavarapu M, Ghosh S, 'Ecotoxicity of mining pollutants on the environment and their remediation', ENVIRONMENTAL CHEMISTRY AND ECOTOXICOLOGY, 5 165-167 (2023) 2023 Maddela NR, Ramakrishnan B, Kadiyala T, Venkateswarlu K, Megharaj M, 'Do Microplastics and Nanoplastics Pose Risks to Biota in Agricultural Ecosystems?', SOIL SYSTEMS, 7 (2023) [C1] Nova 2023 Al Amin M, Luo Y, Shi F, Yu L, Liu Y, Nolan A, et al., 'A modified TOP assay to detect per- and polyfluoroalkyl substances in aqueous film-forming foams (AFFF) and soil.', Front Chem, 11 1141182 (2023) [C1] Nova 2023 Murugesan M, Reedman L, Brinsmead TS, Rifkin W, Gordon J, Megharaj M, 'Modelling least-cost technology pathways to decarbonise the New South Wales energy system by 2050', Renewable and Sustainable Energy Transition, 3 (2023) [C1]

Deep decarbonisation pathways can enable the state of New South Wales (NSW) in Australia to reach a net-zero emissions reduction goal and contribute to global mitigation efforts t... [more]

Deep decarbonisation pathways can enable the state of New South Wales (NSW) in Australia to reach a net-zero emissions reduction goal and contribute to global mitigation efforts to limit temperature rise to 1.5 °C by mid-century. This paper explores minimum cost solutions for achieving the corresponding greenhouse gas (GHG) emissions reduction target for NSW, using an Australian implementation of the TIMES (The Integrated MARKAL-EFOM System) energy system modelling framework. This paper investigated possible decarbonisation pathways and available technology options to reach the target. It includes both a higher emissions reference case scenario and a scenario implementing the NSW state government's target of net-zero emissions by 2050 under the NSW Climate Change Policy Framework, consistent with the international Paris Agreement on climate change, with available and viable well-developed technologies. The findings show that the NSW energy system can continue its shift from fossil fuels to renewables like solar, wind, and hydro and can entirely phase out coal- and gas-fired electricity generation by 2050. The deployment of zero-emissions technologies along with policy supports are crucial to achieving deep decarbonisation of the NSW economy by 2050. In addition, electrification and energy efficiency improvements play a significant role in the end-use sector's energy consumption reduction in the coming decades. This paper shows that the electricity sector is the dominant contributor to emission reductions up to the year 2030, while transport, buildings, and industry sectors are set to decarbonise later in the projection period (2030¿2050) along this least-cost trajectory. However, the NSW government's aspirational target of net-zero emissions by 2050 can be achieved by 2039 by offsetting negative emissions.

Nova 2023 Kuppan P, Sudharsanam A, Venkateswarlu K, Megharaj M, 'Solar technology-closed loop synergy facilitates low-carbon circular bioeconomy in microalgal wastewater treatment', NPJ CLEAN WATER, 6 (2023) [C1] Nova 2023 Meftaul IM, Venkateswarlu K, Annamalai P, Parven A, Megharaj M, 'Degradation of four pesticides in five urban landscape soils: human and environmental health risk assessment (May, 10.1007/s10653-022-01278-w, 2022)', ENVIRONMENTAL GEOCHEMISTRY AND HEALTH, 45 1615-1615 (2023) 2023 Ma X, Tian H, Dai Y, Yang Y, Megharaj M, He W, 'Respecting catalytic efficiency of soil arylsulfatase as soil Sb contamination bio-indicator by enzyme kinetic strategy', ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 30 17644-17656 (2023) [C1] Nova 2023 Dhar K, Venkateswarlu K, Megharaj M, 'Anoxygenic phototrophic purple non-sulfur bacteria: tool for bioremediation of hazardous environmental pollutants.', World J Microbiol Biotechnol, 39 283 (2023) [C1] Nova 2023 Samarasinghe SVAC, Krishnan K, Aitken RJ, Naidu R, Megharaj M, 'Chronic effects of TiO2 and ZnO nanoparticles to earthworm Eisenia fetida', Environmental Chemistry and Ecotoxicology, 5 129-134 (2023) [C1] Nova 2023 Dhar K, Panneerselvan L, Subashchandrabose SR, Venkateswarlu K, Megharaj M, 'Anaerobic Degradation of Naphthalene and Pyrene by Sulfate-Reducing Cultures Enriched from Former Manufactured Gas Plant Soil.', Microbial ecology, 86 271-281 (2023) [C1] Nova 2023 Al Amin M, Luo Y, Nolan A, Mallavarapu M, Naidu R, Fang C, 'Thermal kinetics of PFAS and precursors in soil: Experiment and surface simulation in temperature-time plane.', Chemosphere, 318 138012 (2023) [C1] Nova 2023 Nguyen MD, Sivaram AK, Megharaj M, Webb L, Adhikari S, Thomas M, et al., 'Investigation on removal of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) using water treatment sludge and biochar', Chemosphere, 338 (2023) [C1]

This work assessed the adsorption performance of three common PFAS compounds (PFOA, PFOS and PFHxS) on two water treatment sludges (WTS) and two biochars (commercial biomass bioch... [more]

This work assessed the adsorption performance of three common PFAS compounds (PFOA, PFOS and PFHxS) on two water treatment sludges (WTS) and two biochars (commercial biomass biochar and semi-pilot scale biosolids biochar). Of the two WTS samples included in this study, one was sourced from poly-aluminium chloride (PAC) and the other from alum (Al2(SO4)3). The results of experiments using a single PFAS for adsorption reinforced established trends in affinity - the shorter-chained PFHxS was less adsorbed than PFOS, and the sulphates (PFOS) were more readily adsorbed than the acid (PFOA). Interestingly, PAC WTS, showed an excellent adsorption affinity for the shorter chained PFHxS (58.8%), than the alum WTS and biosolids biochar at 22.6% and 41.74%, respectively. The results also showed that the alum WTS was less effective at adsorption than the PAC WTS despite having a larger surface area. Taken together, the results suggest that the hydrophobicity of the sorbent and the chemistry of the coagulant were critical factors for understanding PFAS adsorption on WTS, while other factors, such as the concentration of aluminium and iron in the WTS could not explain the trends seen. For the biochar samples, the surface area and hydrophobicity are believed to be the main drivers in the different performances. Adsorption from the solution containing multiple PFAS was also investigated with PAC WTS and biosolids biochar, demonstrating comparable performance on overall adsorption. However, the PAC WTS performed better with the short-chain PFHxS than the biosolids biochar. While both PAC WTS and biosolids biochar are promising candidates for adsorption, the study highlights the need to explore further the mechanisms behind PFAS adsorption, which could be a highly variable source to understand better the potential for WTS to be utilized as a PFAS adsorbent.

Nova 2023 Sana T, Chowdhury MI, Logeshwaran P, Megharaj M, 'Behavioural, developmental and reproductive toxicological impacts of perfluorobutanoic acid (PFBA) in Caenorhabditis elegans', Environmental Challenges, 10 100662-100662 (2023) [C1] Nova 2023 Aththanayake AMKCB, Rathnayake IVN, Deeyamulla MP, Megharaj M, 'Staphylococcus edaphicus KCB02A11 incorporated with natural adsorbents: first report on its tolerance and removal of hexavalent chromium [Cr(VI)].', World J Microbiol Biotechnol, 39 173 (2023) [C1] Nova 2023 Majid N, Bahar MM, Harper R, Megharaj M, Naidu R, 'Influence of biotic and abiotic factors on the development of non-wetting soils and management approaches: A review', Soil Security, 11 100091-100091 (2023) [C1] Nova 2023 Li N, Wang Z, Tian H, Megharaj M, He W, 'Ecotoxicity of soil Pb pollution reflected by soil ß-glucosidase: Comparison of extracellular and intracellular enzyme pool.', Sci Total Environ, 882 163364 (2023) [C1] Nova 2023 Dhar K, Abinandan S, Sana T, Venkateswarlu K, Megharaj M, 'Anaerobic biodegradation of phenanthrene and pyrene by sulfate-reducing cultures enriched from contaminated freshwater lake sediments', Environmental Research, 235 116616-116616 (2023) [C1] Nova 2023 Gao T, Tian H, Niu H, Wang Z, Dai Y, Megharaj M, He W, 'Soil phosphatase assay to evaluate arsenic toxicity should be performed at the soil's actual pH', SCIENCE OF THE TOTAL ENVIRONMENT, 859 (2023) [C1] Nova 2023 Dhar K, Sivaram AK, Panneerselvan L, Venkateswarlu K, Megharaj M, 'Efficient bioremediation of laboratory wastewater co-contaminated with PAHs and dimethylformamide by a methylotrophic enrichment culture.', J Environ Manage, 325 116425 (2023) [C1] Nova 2023 Mahbub KR, Chénard C, Batinovic S, Petrovski S, Lauro FM, Rahman MH, et al., 'Complex interactions between diverse mobile genetic elements drive the evolution of metal-resistant bacterial genomes', Environmental Microbiology, 25 3387-3405 (2023) [C1]

In this study, we compared the genomes of three metal-resistant bacteria isolated from mercury-contaminated soil. We identified diverse and novel MGEs with evidence of multiple LG... [more]

In this study, we compared the genomes of three metal-resistant bacteria isolated from mercury-contaminated soil. We identified diverse and novel MGEs with evidence of multiple LGT events shaping their genomic structure and heavy metal resistance. Among the three metal-resistant strains, Sphingobium sp SA2 and Sphingopyxis sp SE2 were resistant to multiple metals including mercury, cadmium, copper, zinc and lead. Pseudoxanthomonas sp SE1 showed resistance to mercury only. Whole genome sequencing by Illumina and Oxford Nanopore technologies was undertaken to obtain comprehensive genomic data. The Sphingobium and Sphingopyxis strains contained multiple chromosomes and plasmids, whereas the Pseudoxanthomonas strain contained one circular chromosome. Consistent with their metal resistance profiles, the strains of Sphingobium and Sphingopyxis contained a higher quantity of diverse metal resistance genes across their chromosomes and plasmids compared to the single-metal resistant Pseudoxanthomonas SE1. In all three strains, metal resistance genes were principally associated with various novel MGEs including genomic islands (GIs), integrative conjugative elements (ICEs), transposons, insertion sequences (IS), recombinase in trio (RIT) elements and group II introns, indicating their importance in facilitating metal resistance adaptation in a contaminated environment. In the Pseudoxanthomonas strain, metal resistance regions were largely situated on a GI. The chromosomes of the strains of Sphingobium and Sphingopyxis contained multiple metal resistance regions, which were likely acquired by several GIs, ICEs, numerous IS elements, several Tn3 family transposons and RIT elements. Two of the plasmids of Sphingobium were impacted by Tn3 family transposons and ISs likely integrating metal resistance genes. The two plasmids of Sphingopyxis harboured transposons, IS elements, an RIT element and a group II intron. This study provides a comprehensive annotation of complex genomic regions of metal resistance associated with novel MGEs. It highlights the critical importance of LGT in the evolution of metal resistance of bacteria in contaminated environments.

Nova 2023 Vidane Arachchige Chamila Samarasinghe S, Krishnan K, John Aitken R, Naidu R, Megharaj M, 'Multigenerational effects of TiO2 rutile nanoparticles on earthworms.', Environ Pollut, 336 122376 (2023) [C1] Nova 2023 Rathnayake IVN, Megharaj M, Naidu R, 'Sol-Gel Immobilized Optical Microalgal Biosensor for Monitoring Cd, Cu and Zn Bioavailability in Freshwater.', Bull Environ Contam Toxicol, 110 73 (2023) [C1] Nova 2023 Li Y, Wang Z, Tian H, Megharaj M, Jia H, He W, 'Using soil enzyme Vmax as an indicator to evaluate the ecotoxicity of lower-ring polycyclic aromatic hydrocarbons in soil: Evidence from fluorescein diacetate hydrolase kinetics', SCIENCE OF THE TOTAL ENVIRONMENT, 874 (2023) [C1] Nova 2023 Tan X, He J, Nie Y, Ni X, Ye Q, Ma L, et al., 'Climate and edaphic factors drive soil enzyme activity dynamics and tolerance to Cd toxicity after rewetting of dry soil.', Sci Total Environ, 855 158926 (2023) [C1] Nova 2023 Meftaul IM, Venkateswarlu K, Parven A, Annamalai P, Megharaj M, 'Human health risk assessment of pesticides in lettuce and spinach grown in urban backyard garden soils', Journal of Food Composition and Analysis, 115 104977-104977 (2023) [C1] Nova 2023 Abinandan S, Praveen K, Venkateswarlu K, Megharaj M, 'Microalgae microplastics interactions at environmentally relevant concentrations: Implications toward ecology, bioeconomy, and UN SDGs', Water Research, 247 120778-120778 (2023) [C1] Nova 2023 Maddela NR, Kakarla D, Venkateswarlu K, Megharaj M, 'Additives of plastics: Entry into the environment and potential risks to human and ecological health.', J Environ Manage, 348 119364 (2023) [C1] Nova 2023 Luo Y, Khoshyan A, Al Amin M, Nolan A, Robinson F, Fenstermacher J, et al., 'Ultrasound-enhanced Magnéli phase Ti

Per-and polyfluoroalkyl substances (PFAS) remediation is still a challenge. In this study, we propose a hybrid system that combines electrochemical treatment with ultrasound irrad... [more]

Per-and polyfluoroalkyl substances (PFAS) remediation is still a challenge. In this study, we propose a hybrid system that combines electrochemical treatment with ultrasound irradiation, aiming for an enhanced degradation of PFAS. Equipped with a titanium suboxide (Ti4O7) anode, the electrochemical cell is able to remove perfluorooctanoic acid (PFOA) effectively. Under the optimal conditions (50 mA/cm2 current density, 0.15 M Na2SO4 supporting electrolyte, and stainless steel/Ti4O7/stainless steel electrode configuration with a gap of ~10 mm), the electrochemical process achieves ~100 % PFOA removal and 43 % defluorination after 6 h. Applying ultrasound irradiation (130 kHz) alone offers a limited PFOA removal, with 33 % PFOA removal and 5.5 % defluorination. When the electrochemical process is combined with ultrasound irradiation, we observe a significant improvement in the remediation performance, with ~100 % PFOA removal and 63.5 % defluorination, higher than the sum of 48.5 % (43 % achieved by the electrochemical process, plus 5.5 % by the ultrasound irradiation), implying synergistic removal/oxidation effects. The hybrid system also consistently shows the synergistic defluorination during degradation of other PFAS and the PFAS constituents in aqueous film forming foam (AFFF). We attribute the synergistic effect to an activated/cleaned electrode surface, improved mass transfer, and enhanced production of radicals.

2023 Kuppusamy S, Venkateswarlu K, Megharaj M, Sellappa K, Lee YB, 'Contamination of long-term manure-fertilized Indian paddy soils with veterinary antibiotics: Impact on bacterial communities and antibiotics resistance genes', Applied Soil Ecology, 192 (2023) [C1]

In the present study, we investigated the implication of long-term fertilization of Indian rice paddies with animal manures on the prevalence of veterinary antibiotics (VAs) resid... [more]

In the present study, we investigated the implication of long-term fertilization of Indian rice paddies with animal manures on the prevalence of veterinary antibiotics (VAs) residues, enrichment of soil microorganisms, and abundance of antibiotic resistance genes (ARGs). The most frequently detected antibiotics in Indian paddy soils were tetracyclines followed by sulfonamides. The soils long-term fertilized with poultry manure (PM) and cow manure (CM) contained significant amounts of VAs (137.20 µg kg-1) in soil. Members of Actinobacteria, Streptomyces, Rubrobacter, Pseudonocardia, Pseudomonas and Rhizobium were predominant in soils that received PM or CM. ARGs such as mtrA, arlR, bcrA, novA, oleC, sul4 and kdpE that confer resistance mostly to macrolides, aminocoumarins, multi-drugs, and sulfonamides were predominant, and the main phyla that contributed ARGs included Actinobacteria (55 %) and Proteobacteria (22 %). Antibiotic modification/degradation was the major (58.30 %) antibiotic resistance mechanism in bacteria enriched in long-term fertilized soils. Residues of tetracyclines, quinolones, sulfonamides, Cu and Cd in soils positively correlated with ARGs. Notably, this study is the first evidence on the prevalence of VAs, antibiotic-resistant microbes, and ARGs in paddy soils of India long-term fertilized with PM or CM and shed light on the interactions between antibiotics, heavy metals and ARGs.

Nova 2023 Ogburn NJ, Duan L, Subashchandrabose SR, Sorgeloos P, O'Connor W, Megharaj M, Naidu R, 'Agricultural wastes for brine shrimp Artemia production: A review', Reviews in Aquaculture, 15 1159-1178 (2023) [C1]

An increasing global population has meant aquaculture, one of the fastest growing food industry sectors, faces significant sustainability challenges as it tries to address the ris... [more]

An increasing global population has meant aquaculture, one of the fastest growing food industry sectors, faces significant sustainability challenges as it tries to address the rising global protein demand. In many sectors, production is underpinned by fishmeal as dietary ingredient, but this is a finite resource with competing users from the poultry and livestock industries. Alternatively, some (planktonic) aquatic species, especially brine shrimp Artemia, can be produced using agricultural waste to provide food or biomass to support increasing aquaculture demand. This review investigates research and production of Artemia using agricultural waste. Various systems used for Artemia production in inoculated ponds are analysed and discussed to provide options for environmentally sustainable food systems that can be applied from either an artisanal level in developing countries with a considerable labour force, or in intensive systems in countries with large volumes of under-utilised resources, for example, sugar/alcohol-based waste and inland saline areas. Using agricultural waste, single cell protein production in a separate aerobic digester can be a simple, continuous food source for Artemia to enable daily biomass harvest. This could then be used as a fishmeal replacement or possibly for human consumption to promote a circular economy by remediating waste to produce protein, like a food production mine.

Nova 2023 Suhani I, Srivastava V, Megharaj M, Suthar S, Garg VK, Singh RP, 'Effect of Compost and Vermicompost Amendments on Biochemical and Physiological Responses of Lady s Finger (Abelmoschus esculentus L.) Grown under Different Salinity Gradients', Sustainability, 15 11590-11590 [C1] Nova 2023 Sivaram AK, Lee E, Curnow A, Surapaneni A, Kannan K, Megharaj M, 'Uptake, accumulation, and toxicity of per- and polyfluoroalkyl substances in Allium cepa grown in soils amended with biosolids', Environmental Challenges, 10 (2023) [C1]

Uptake and accumulation of per- and polyfluoroalkyl substances (PFAS) in Allium cepa from soils amended with biosolids were investigated. The ¿38 PFAS concentrations in soils amen... [more]

Uptake and accumulation of per- and polyfluoroalkyl substances (PFAS) in Allium cepa from soils amended with biosolids were investigated. The ¿38 PFAS concentrations in soils amended with biosolids ranged from 10.4 to 104 ng g-1 (dry-weight). Among PFAS, perfluorooctanesulfonate (PFOS) concentration was the highest in soils, with a maximum of 48.1 ng g-1, followed by N-ethylperfluoro-1-octanesulfonamidoacetic acid (N-Et-FOSAA) with the maximum of 10.9 ng g-1. The concentration of perfluorooctanoate (PFOA) was higher (0.55¿1.82 ng g-1) in roots of A. cepa than that of PFOS (0.03¿0.13 ng g-1). The accumulation of PFAS in A. cepa shoots depended on the carbon chain length, with a more significant accumulation of shorter C-chain PFAS than the longer C-chain derivatives. The concentration of PFAS in shoots correlated positively with corresponding root concentration, suggesting a significant translocation of PFAS from root to shoots. A. cepa showed no considerable cyto-genotoxicity in the meristem root tip cells exposed to soils amended with biosolids. The oxidative stress parameters such as reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and lipid peroxidation (LP) showed no significant change over control in A. cepa root cells exposed to soils amended with biosolids. The estimated dietary intake for PFOA and PFOS did not exceed the recommended tolerable daily intake (TDI) even after assuming that onion accounted for 100% of vegetable consumption. This study provides evidence of accumulation and translocation of PFAS from soil to roots and shoots of A. cepa. Also, we assessed the potential risk of PFAS accumulated in A. cepa to humans via the food chain to be insignificant.

Nova 2023 Nurzhan A, Tian H, Nuralykyzy B, Li H, Ma X, Megharaj M, He W, 'Arsenic mobility and toxicity on soil acid phosphatase activity increased with added phosphorus in contaminated mine soils', SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 87 246-259 (2023) [C1] 2023 Luo Y, Awoyemi OS, Gopalan S, Nolan A, Robinson F, Fenstermacher J, et al., 'Investigating the effect of polarity reversal of the applied current on electrochemical degradation of per-and polyfluoroalkyl substances', Journal of Cleaner Production, 433 139691-139691 (2023) [C1] Nova 2022 Liu C, Tian H, Gu X, Li N, Zhao X, Lei M, et al., 'Catalytic efficiency of soil enzymes explains temperature sensitivity: Insights from physiological theory.', Sci Total Environ, 822 153365 (2022) [C1] Nova 2022 Morrissy JG, Currell MJ, Reichman SM, Surapaneni A, Megharaj M, Crosbie ND, et al., 'The Variation in Groundwater Microbial Communities in an Unconfined Aquifer Contaminated by Multiple Nitrogen Contamination Sources', Water (Switzerland), 14 (2022) [C1]

Aquifers provide integral freshwater resources and host ecosystems of largely uncharacterized, truncated endemic microorganisms. In recent history, many aquifers have become incre... [more]

Aquifers provide integral freshwater resources and host ecosystems of largely uncharacterized, truncated endemic microorganisms. In recent history, many aquifers have become increasingly contaminated from various anthropogenic sources. To better understand the impacts of nitrogen contamination on native groundwater ecosystems, 16S rRNA sequencing of the groundwater microbial communities was carried out. Samples were taken from an aquifer known to be contaminated with nitrogen from multiple sources, including fertilizers and wastewater treatment plant effluents. In total, two primary contaminants were identified: NH4+ (<0.1¿3.7¿26 mg L-1 NH4+ minmedian-max), and NO3- (<0.01¿18¿150 mg L-1 NO3- min-median-max). These contaminants were found to be associated with a decrease/increase in microbial species richness within affected groundwater for NH4+/NO3-, respectively. Important phyla were identified, including Proteobacteria, which had the highest abundance within samples unaffected by NH4+ (36¿81% NH4+ unaffected, 4¿33% NH4+ affected), and Planctomycetes (0.05¿10% NH4+ unaffected, 43¿72% NH4+ affected), which had the highest abundance within the NH4+ affected samples, likely due to its ability to perform anaerobic ammonia oxidation (ANAMMOX). Planctomycetes were identified as a potential indicator for the presence of NH4+ contamination. The analysis and characterization of sequencing data alongside physicochemical data showed potential to increase the depth of our understanding of contaminant behavior and fate within a contaminated aquifer using this type of data and analysis.

Nova 2022 Aththanayake AMKCB, Rathnayake IVN, Deeyamulla MP, Megharaj M, 'Potential use of Nova 2022 Sivaram AK, Logeshwaran P, Abinandan S, Mukunthan K, Megharaj M, 'Cyto-genotoxicity evaluation of pyroligneous acid using Nova 2022 Praveen K, Abinandan S, Venkateswarlu K, Megharaj M, 'Sustainability Evaluation of Immobilized Acid-Adapted Microalgal Technology in Acid Mine Drainage Remediation Following Emergy and Carbon Footprint Analysis', Molecules, 27 (2022) [C1]

Sustainability evaluation of wastewater treatment helps to reduce greenhouse gas emis-sions, as it emphasizes the development of green technologies and optimum resource use rather... [more]

Sustainability evaluation of wastewater treatment helps to reduce greenhouse gas emis-sions, as it emphasizes the development of green technologies and optimum resource use rather than the end-of-pipe treatment. The conventional approaches for treating acid mine drainages (AMDs) are efficient; however, they need enormous amounts of energy, making them less sustainable and causing greater environmental concern. We recently demonstrated the potential of immobilized acid-adapted microalgal technology for AMD remediation. Here, this novel approach has been evaluated following emergy and carbon footprint analysis for its sustainability in AMD treat-ment. Our results showed that imported energy inputs contributed significantly (>90%) to the overall emergy and were much lower than in passive and active treatment systems. The microalgal treatment required 2¿15 times more renewable inputs than the other two treatment systems. Addition-ally, the emergy indices indicated higher environmental loading ratio and lower per cent renewa-bility, suggesting the need for adequate renewable inputs in the immobilized microalgal system. The emergy yield ratio for biodiesel production from the microalgal biomass after AMD treatment was >1.0, which indicates a better emergy return on total emergy spent. Based on greenhouse gas emissions, carbon footprint analysis (CFA), was performed using default emission factors, in ac-cordance with the IPCC standards and the National Greenhouse Energy Reporting (NGER) program of Australia. Interestingly, CFA of acid-adapted microalgal technology revealed significant greenhouse gas emissions due to usage of various construction materials as per IPCC, while SCOPE 2 emissions from purchased electricity were evident as per NGER. Our findings indicate that the immobilized microalgal technology is highly sustainable in AMD treatment, and its potential could be realized further by including solar energy into the overall treatment system.

Nova 2022 Logeshwaran P, Subashchandrabose SR, Krishnan K, Sivaram AK, Annamalai P, Naidu R, Megharaj M, 'Polycyclic aromatic hydrocarbons biodegradation by fenamiphos degrading Microbacterium esteraromaticum MM1', Environmental Technology and Innovation, 27 (2022) [C1]

A Gram-positive bacterium, Microbacterium esteraromaticum MM1 able to degrade organophosphorus pesticides such as fenamiphos and malathion, also possessed the ability to degrade h... [more]

A Gram-positive bacterium, Microbacterium esteraromaticum MM1 able to degrade organophosphorus pesticides such as fenamiphos and malathion, also possessed the ability to degrade high molecular weight polycyclic aromatic hydrocarbon (PAH), pyrene (Pyr) and benzo[a]pyrene (BaP). The strain MM1 degraded 98.7% of initially spiked 100 mg L-1 pyrene within 15 days from the M9 mineral salts medium (pH 7.0) with 0.1% glucose. At optimal pH 7.0, 57.81% of pyrene (100 mg L-1) was degraded as the sole carbon source. In order to determine the influence of carbon sources (glucose, sodium acetate, sodium succinate) and PAHs (Naphthalene (Nap), Phenanthrene (Phe), Benzo[a]pyrene (BaP)) on pyrene degradation, a full factorial design analysis was conducted. Among the carbon sources examined, glucose, sodium acetate, and all the PAHs positively affected pyrene degradation. Interestingly, in the presence of other PAHs, benzo[a]pyrene was degraded by MM1 but not as the sole carbon source. Crude enzyme extracted from MM1 degraded pyrene with the Km and Vmax values of 49.3 µg ml-1 (equivalent to 250 µM) and 9.5 µg ml-1 min-1 mg-1 of crude protein (equivalent to 50 µM), respectively with a specific activity of 0.19 µg ml-1 mg-1 of crude protein. Metabolites such as monohydroxypyrene, 2,6-di-isopropylnaphthalene, and phthalic acid were identified during pyrene degradation by MM1. Differential expression of the protein in the presence of pyrene resulted in the inducement of enolase (phosphopyruvate hydratase) and pyridine nucleotide-disulphide oxidoreductase in MM1. To the best of our knowledge, this is the first report on the degradation of pyrene by M. esteraromaticum MM1.

Nova 2022 Dhar K, Panneerselvan L, Venkateswarlu K, Megharaj M, 'Efficient bioremediation of PAHs-contaminated soils by a methylotrophic enrichment culture.', Biodegradation, 33 575-591 (2022) [C1] Nova 2022 Perera IA, Abinandan S, Panneerselvan L, Subashchandrabose SR, Venkateswarlu K, Naidu R, Megharaj M, 'Co-culturing of microalgae and bacteria in real wastewaters alters indigenous bacterial communities enhancing effluent bioremediation', ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, 64 (2022) [C1] Nova 2022 Maddela NR, Ramakrishnan B, Dueñas-Rivadeneira AA, Venkateswarlu K, Megharaj M, 'Chemicals/materials of emerging concern in farmlands: sources, crop uptake and potential human health risks.', Environ Sci Process Impacts, 24 2217-2236 (2022) [C1] Nova 2022 Perera IA, Abinandan S, Subashchandrabose SR, Venkateswarlu K, Cole N, Naidu R, Megharaj M, 'Extracellular Polymeric Substances Drive Symbiotic Interactions in Bacterial Microalgal Consortia.', Microb Ecol, 83 596-607 (2022) [C1] Nova 2022 Perera IA, Abinandan S, Subashchandrabose SR, Venkateswarlu K, Naidu R, Megharaj M, 'Combined inorganic nitrogen sources influence the release of extracellular compounds that drive mutualistic interactions in microalgal-bacterial co-cultures', JOURNAL OF APPLIED PHYCOLOGY, 34 1311-1322 (2022) [C1] Nova 2022 Raju Maddela N, Ramakrishnan B, Kakarla D, Venkateswarlu K, Megharaj M, 'Major contaminants of emerging concern in soils: a perspective on potential health risks', RSC ADVANCES, 12 12396-12415 (2022) [C1] Nova 2022 Morrissy JG, Reichman SM, Currell MJ, Surapaneni A, Megharaj M, Crosbie ND, et al., 'Differentiation between Impacted and Unimpacted Microbial Communities of a Nitrogen Contaminated Aquifer', Environments, 9 128-128 [C1] Nova 2022 Perera IA, Abinandan S, Subashchandrabose SR, Venkateswarlu K, Naidu R, Megharaj M, 'Impact of Nitrate and Ammonium Concentrations on Co-Culturing of Tetradesmus obliquus IS2 with Variovorax paradoxus IS1 as Revealed by Phenotypic Responses', MICROBIAL ECOLOGY, 83 951-959 (2022) [C1] Nova 2022 Ma X, Tian H, Liao M, Huang Y, Yang R, Guo Z, et al., 'Toxicity of antimony in 18 soils of China evaluated by soil dehydrogenase activity', SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 86 703-713 (2022) [C1] Nova 2022 Chowdhury MI, Sana T, Panneerselvan L, Sivaram AK, Megharaj M, 'Perfluorooctane sulfonate (PFOS) induces several behavioural defects in Caenorhabditis elegans that can also be transferred to the next generations.', Chemosphere, 291 132896 (2022) [C1] Nova 2022 Ojo AF, Peng C, Annamalai P, Megharaj M, Ng JC, 'Toxicity assessment of historical aqueous film-forming foams (AFFFs) using cell-based assays.', Environ Pollut, 310 119806 (2022) [C1] Nova 2022 Jayaramaiah RH, Egidi E, Macdonald CA, Wang J-T, Jeffries TC, Megharaj M, Singh BK, 'Soil initial bacterial diversity and nutrient availability determine the rate of xenobiotic biodegradation.', Microb Biotechnol, 15 318-336 (2022) [C1] Nova 2022 Abinandan S, Shanthakumar S, Panneerselvan L, Venkateswarlu K, Megharaj M, 'Algalization of Acid Soils with Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 Enriches Bacteria of Ecological Importance', ACS Agricultural Science and Technology, 2 512-520 (2022) [C1]

Acid soils are the degraded (nutrient-poor) soils that generally lack microbial abundance required to promote plant growth. An insight into the microbial diversity in highly acidi... [more]

Acid soils are the degraded (nutrient-poor) soils that generally lack microbial abundance required to promote plant growth. An insight into the microbial diversity in highly acidic soils is crucial from both ecological and environmental standpoints. Previously, we showed that inoculation of acid soils with acid-tolerant microalgae (algalization) significantly improved soil physicochemical and biological characteristics. In the present novel study involving a laboratory microcosm, high-throughput 16S rRNA amplicon sequencing analysis was performed to investigate the bacterial diversity in acid soils algalized with Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 after 90 days of incubation. Our results on pooled DNA demonstrate that algalization of two acid soils (soil A and B) significantly increased several bacterial genera, and this observation is consistent with Shannon and Chao1 diversity indices. Actinobacteria, Acidobacteria, Firmicutes, and Proteobacteria were the most prevalent phyla enriched in all of the algalized treatments. Interestingly, nonalgalized acid soils favored only Firmicutes and Actinobacteria, but algalization significantly enriched Proteobacteria, Acidobacteria, and Actinobacteria. Canonical correspondence analysis revealed a positive effect of pH in soil A and both pH and organic carbon in soil B on enrichment. Furthermore, soil bacteria of ecological significance that belong to rhizobacteria and diazotrophs, such as Acetobacter, Azospirillum, Bradyrhizobium, Gluconacetobacter, Nitrobacter, Burkholderia, Comamonas, Herbaspirillum, Enterobacter, Nitrosococcus, Brevibacillus, Enterococcus, Frankia, and Anabaena, were greatly enriched in algalized treatments. Thus, we demonstrate here for the first time that algalization of acid soils significantly improves soil health through enrichment of bacteria that are largely implicated in promoting soil health and plant growth

Nova 2022 Abbasi S, Lamb DT, Choppala G, Burton ED, Megharaj M, 'Antimony speciation, phytochelatin stimulation and toxicity in plants.', Environ Pollut, 305 119305 (2022) [C1] Nova 2022 Naidu V, Hyde L, Eijkelkamp BA, Megharaj M, Subashchandrabose S, Hassan KA, 'Complete Genome Sequence of Rhodococcus sp. Strain 9, Isolated from Contaminated Australian Groundwater', MICROBIOLOGY RESOURCE ANNOUNCEMENTS, 11 (2022) 2022 Li H, Tian H, Wang Z, Liu C, Nurzhan A, Megharaj M, He W, 'Potential effect of warming on soil microbial nutrient limitations as determined by enzymatic stoichiometry in the farmland from different climate zones', SCIENCE OF THE TOTAL ENVIRONMENT, 802 (2022) [C1] Nova 2022 Sivaram AK, Panneerselvan L, Surapaneni A, Lee E, Kannan K, Megharaj M, 'Per- and polyfluoroalkyl substances (PFAS) in commercial composts, garden soils, and potting mixes of Australia', Environmental Advances, 7 (2022) [C1]

In developing and developed countries, urban gardening has increasingly become an integral part of local food systems for good quality produce, for enhanced urban health and susta... [more]

In developing and developed countries, urban gardening has increasingly become an integral part of local food systems for good quality produce, for enhanced urban health and sustainability. There are few gardens with naturally perfect soils for growing plants. However, the soils with poor texture and fewer nutrients can be improved by different types of organic amendments such as composts, garden soils and organic potting mixes that are commercially available in the consumer markets worldwide to promote healthy plant growth. In this study, we assessed 19 different commercially available composts, garden soils, and potting mixes for the presence of 38 per- and polyfluoroalkyl substances (PFAS). The total (¿38) PFAS in the samples ranged between 1.26 to 11.84 µg kg-1 (dry weight). The total concentration of perfluorinated carboxylic acids (¿PFCAs) was higher than that of perfluoroalkyl sulfonic acids (PFSAs) in all products. The total oxidizable precursor assay (TOPA) was applied in the analysis of composts and potting mixes, which revealed an increase in short-chain ¿PFCAs concentrations ranging from 0.48 to 7.63 µg kg-1, which suggested the transformation of PFCAs precursors to short-chain PFCAs. The measured concentrations of short-chain PFCAs after TOPA in the soil substrates have the potential to contribute to plant uptake and food chain transfer of PFAS to humans due to their high mobility.

Nova 2022 Sivaram AK, Panneerselvan L, Mukunthan K, Megharaj M, 'Effect of Pyroligneous Acid on the Microbial Community Composition and Plant Growth-Promoting Bacteria (PGPB) in Soils', Soil Systems, 6 (2022) [C1]

Pyroligneous acid (PA) is often used in agriculture as a plant growth and yield enhancer. However, the influence of PA application on soil microorganisms is not often studied. The... [more]

Pyroligneous acid (PA) is often used in agriculture as a plant growth and yield enhancer. However, the influence of PA application on soil microorganisms is not often studied. Therefore, in this study, we investigated the effect of PA (0.01¿5% w/w in soil) on the microbial diversity in two different soils. At the end of eight weeks of incubation, soil microbial community dynamics were determined by Illumina-MiSeq sequencing of 16S rRNA gene amplicons. The microbial composition differed between the lower (0.01% and 0.1%) and the higher (1% and 5%) concentration in both PA spiked soils. The lower concentration of PA resulted in higher microbial diversity and dehydrogenase activity (DHA) compared to the un-spiked control and the soil spiked with high PA concentrations. Interestingly, PA-induced plant growth-promoting bacterial (PGPB) genera include Bradyrhizobium, Azospirillum, Pseudomonas, Mesorhizobium, Rhizobium, Herbaspiriluum, Acetobacter, Beijerinckia, and Nitrosomonas at lower concentrations. Additionally, the PICRUSt functional analysis revealed the predominance of metabolism as the functional module¿s primary component in both soils spiked with 0.01% and 0.1% PA. Overall, the results elucidated that PA application in soil at lower concentrations promoted soil DHA and microbial enrichment, particularly the PGPB genera, and thus have great implications for improving soil health.

Nova 2021 Halim MA, Rahman MM, Mondal D, Megharaj M, Naidu R, 'Bioaccumulation and Tolerance Indices of Cadmium in Wheat Plants Grown in Cadmium-Spiked Soil: Health Risk Assessment', Frontiers in Environmental Science, 9 (2021) [C1]

Farmers use wastewater for irrigation in many developing countries, for example Bangladesh, India, China, Sri Lanka and Vietnam because they have limited access to clean water. Th... [more]

Farmers use wastewater for irrigation in many developing countries, for example Bangladesh, India, China, Sri Lanka and Vietnam because they have limited access to clean water. This study explored cadmium (Cd) bioaccumulation in two spring wheat cultivars (cv. Mustang and Lancer), which were grown in different concentrations of Cd (0,1, 2, 4, and 8¿mg kg-1) in agricultural soils. The half maximum inhibitory concentration (IC50) values were 4.21 ± 0.29 and 4.02 ± 0.95, respectively, whereas the maximum health risk index (HRI) was 3.85 ± 0.049 and 5.33 ± 0.271, respectively, for Mustang and Lancer. In other words, the malondialdehyde content increased significantly in Mustang (around five-fold) and Lancer (around four-fold) compared with the control treatment. Results revealed that Cd content was well above the acceptable limit (HRI >1) in the two cultivars when exposed to different levels of Cd stress. The tolerant cultivar (Mustang) has potential to chelate Cd in the nonedible parts of plants in variable fractions and can be used efficiently to improve growth and macro- and micro-nutrients content while reducing Cd concentration in plants in Cd-contaminated soil. It can also diminish the HRI, which may help to protect humans from Cd risks. The two cultivars¿ nutrient availability and sorption capacity significantly shape their survival and adaptability under Cd stress. Based on what is documented in the current study, we can conclude that Mustang is more tolerant and poses fewer health hazards to people than Lancer because of its capacity to maintain grain macro- and micro-nutrients under Cd stress.

Nova 2021 Sobhani Z, Panneerselvan L, Fang C, Naidu R, Megharaj M, 'Chronic and Transgenerational Effects of Polystyrene Microplastics at Environmentally Relevant Concentrations in Earthworms ( Nova 2021 Sobhani Z, Panneerselvan L, Fang C, Naidu R, Megharaj M, 'Chronic and transgenerational effects of polyethylene microplastics at environmentally relevant concentrations in earthworms', ENVIRONMENTAL TECHNOLOGY & INNOVATION, 25 (2021) [C1] Nova 2021 Parven A, Khan MSI, Prodhan MDH, Venkateswarlu K, Megharaj M, Meftaul IM, 'Human health risk assessment through quantitative screening of insecticide residues in two green beans to ensure food safety', Journal of Food Composition and Analysis, 103 (2021) [C1]

Food contamination with pesticide residues is a serious concern, particularly in developing countries. The study analyzed samples of country bean (Lablab purpureus L.) and yard lo... [more]

Food contamination with pesticide residues is a serious concern, particularly in developing countries. The study analyzed samples of country bean (Lablab purpureus L.) and yard long bean (Vigna unguiculata L.) for residues of widely used insecticides to ensure food safety. We used a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method followed by gas chromatography (GC)-flame thermionic detector (FTD) for quantitative estimation of pesticide residues. Mostly, the residues of chlorpyrifos, dimethoate and quinalphos were found in 11 and 14 % of country bean and yard long bean samples, respectively. About 50 % of the insecticide-contaminated bean samples contained residues above the maximum residue limit (MRL), which warrants a caution about the extensive and intensive use of pesticides in modern agriculture. The general claim of pesticide adulteration could contribute to the widespread occurrence of several insecticides in beans that threatens food safety. The assessment for chronic non-cancer health risk, based on estimated daily intake (EDI) and hazard quotient (HQ), suggests that the consumption of insecticide-contaminated beans poses potential threat to the health of adults (EDI: 2.79 × 10-4¿2.96 × 10-4 and HQ: 0.56¿0.59) as well as children (EDI: 9.79 × 10-4¿1.77 × 10¿3 and HQ: 1.96¿3.55). Overall, our results clearly indicate that around 50 % of insecticide-contaminated bean samples, available at various local markets in Bogura district of Bangladesh, may cause health risks in humans. The present observations might help the regulatory authorities concerned in setting new guidelines for the limits of pesticide residues in commonly used bean vegetables, and in monitoring the quality of commercial formulations.

Nova 2021 Tan X, Nie Y, Ma X, Guo Z, Liu Y, Tian H, et al., 'Soil chemical properties rather than the abundance of active and potentially active microorganisms control soil enzyme kinetics', Science of the Total Environment, 770 (2021) [C1]

Soil enzymes secreted by microorganisms play a critical role in nutrient cycling, soil structure maintenance, and crop production. However, understanding of the linkage between so... [more]

Soil enzymes secreted by microorganisms play a critical role in nutrient cycling, soil structure maintenance, and crop production. However, understanding of the linkage between soil enzyme kinetics and microbial metabolism and active microbial communities is remarkably limited. In this study, we measured the kinetics of three hydrolase enzymes, active microbial abundance and substrate-induced respiration (SIR) from 21 farmlands differing in their fertilities collected from the Loess Plateau, China. Results showed the high fertility soils had higher total organic carbon (TOC) and nutrient contents, potential microbial activity, the colony-forming units (CFU) of actinomycetes, and values of enzyme Vmax and Km than those of low fertility soils. We also observed that the CFU of fungi and other bacterial groups did not change with soil fertility status. Soil chemical properties explained 74.0% of the variance in Vmax and 28.3% of the variance in Km, respectively. Whereas, the abundance of main microbial groups and fungi/bacteria ratio only explained 10.2% and 7% of the variance of Vmax and Km, respectively. The interactive effect of soil properties and microbial community could explain 20.2% of the variance in Km. Our results suggest that the substrate availability would mainly drive enzyme kinetics compared to the abundance of active/potentially active microbes in the farmland soils.

Nova 2021 Tao K, Tian H, Fan J, Li D, Liu C, Megharaj M, et al., 'Kinetics and catalytic efficiency of soil fluorescein diacetate hydrolase under the pesticide parathion stress', Science of the Total Environment, 771 (2021) [C1]

Fluorescein diacetate hydrolase (FDA¿H) is an accurate biochemical method measuring the total microbial activity in soil, which indicates soil quality under ambient environmental ... [more]

Fluorescein diacetate hydrolase (FDA¿H) is an accurate biochemical method measuring the total microbial activity in soil, which indicates soil quality under ambient environmental changes such as pesticide parathion (PTH). However, the influence of PTH on the kinetics of FDA¿H is still unknown. In this study, fifteen farmland soils were exposed to acute PTH pollution to investigate how the kinetic characteristics of FDA¿H change with PTH concentration. Results showed that PTH strongly inhibited the FDA¿H activities. The values of maximum reaction velocity (Vmax) ranged from 0.29 to 2.18 × 10-2 mM g-1 soil h-1 and declined by 42.30%¿71.01% under PTH stress. The Michaelis constant (Km) values ranged between 2.90 and 14.17 × 10-2 mM and exhibited three forms including unchanged, increased (38.16¿242.65%) and decreased (13.41¿39.23%) when exposed to PTH. Based on the changes in two kinetic parameters, the inhibition of PTH on FDA¿H was classified as three types, i.e., noncompetitive, linear mixed and uncompetitive inhibition. The competitive inhibition constant (Kic) and noncompetitive constant (Kiu) ranged from 0.064 to 0.447 mM and 0.209 to 0.723 mM, respectively, which were larger than the Km in values. The catalytic efficiency (Vmax/Km) of FDA¿H is a sensitive integrated parameter to evaluate the PTH toxicity due to the higher inhibition ratio than the Vmax. The PTH toxicity to FDA¿H decreased with increase of soil organic matter and total nitrogen contents. This implied that the PTH toxicity could be alleviated by an increasing content of soil organic matter due to its buffering capacity to PTH. Besides, soils with a higher content of total nitrogen could provide stable environment for FDA¿H to maintain its functionality under PTH pollution. Thus, the results of this study have great implications to the risk assessment of parathion in soils.

Nova 2021 Logeshwaran P, Sivaram AK, Surapaneni A, Kannan K, Naidu R, Megharaj M, 'Exposure to perfluorooctanesulfonate (PFOS) but not perflurorooctanoic acid (PFOA) at ppb concentration induces chronic toxicity in Daphnia carinata', Science of the Total Environment, 769 (2021) [C1]

Widespread environmental contamination of per- and polyfluoroalkyl substances (PFAS) is well established. Nevertheless, few studies have reported on the aquatic toxicity of PFAS, ... [more]

Widespread environmental contamination of per- and polyfluoroalkyl substances (PFAS) is well established. Nevertheless, few studies have reported on the aquatic toxicity of PFAS, especially in indicator species such as Daphnia. In this study, the toxicity of two major PFAS, namely perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), was investigated on water flea (Daphnia carinata) using a battery of comprehensive toxicity tests, including a 48 h acute and a 21-day chronic assays. The survival, growth, and reproduction of D. carinata were monitored over a 21-day life cycle. PFOS exhibited higher toxicity than PFOA. The 48 h LC50 values (confidence interval) based on acute toxicity for PFOA and PFOS were 78.2 (54.9¿105) mg L-1 and 8.8 (6.4¿11.6) mg L-1, respectively. Chronic exposure to PFOS for 21 days displayed mortality and reproductive defects in D. carinata at a concentration as low as 0.001 mg L-1. Genotoxicity assessment using comet assay revealed that exposure for 96 h to PFOS at 1 and 10.0 mg L-1 significantly damaged the organism's genetic makeup. The results of this study have great implications for risk assessment of PFOS and PFOA in aquatic ecosystems, given the potential of PFOS to pose a risk to Daphnia even at lower concentrations (1 µg L-1).

Nova 2021 Kundu S, Patel S, Halder P, Patel T, Hedayati Marzbali M, Pramanik BK, et al., 'Removal of PFASs from biosolids using a semi-pilot scale pyrolysis reactor and the application of biosolids derived biochar for the removal of PFASs from contaminated water', Environmental Science: Water Research and Technology, 7 638-649 (2021) [C1]

This study focuses on the conversion of biosolids to biochar and its further use in adsorbing per- and polyfluoroalkyl substances (PFASs) from contaminated water. In particular, t... [more]

This study focuses on the conversion of biosolids to biochar and its further use in adsorbing per- and polyfluoroalkyl substances (PFASs) from contaminated water. In particular, this study aims to (a) investigate the performance of a semi-pilot fluidised bed pyrolysis unit in converting biosolids into biochar, (b) examine the ability of the pyrolysis-combustion integrated process to destruct PFASs present in biosolids and (c) study the application of biosolids derived biochar for removing PFASs from contaminated water. The semi-pilot fluidised bed pyrolysis unit demonstrated stable temperature and oxygen profiles in the reactor. The yield of biochar was found to be 36-45% at studied temperatures (500-600 °C). The produced biosolids derived biochar samples, due to their lower H/C and O/C ratio, were found to be extremely stable with an expected long (millennia) residence time in soil. It was concluded that >90% removal of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) from biosolids derived biochar could be achieved in the pyrolysis-combustion integrated process. The biosolids derived biochar demonstrated >80% adsorption of long-chain PFASs and 19-27% adsorption of short-chain PFASs from PFAS contaminated water. This journal is

Nova 2021 Sobhani Z, Fang C, Naidu R, Megharaj M, 'Microplastics as a vector of toxic chemicals in soil: Enhanced uptake of perfluorooctane sulfonate and perfluorooctanoic acid by earthworms through sorption and reproductive toxicity', Environmental Technology and Innovation, 22 (2021) [C1]

The accumulation of microplastics (MP) in soil via their continuous release and degradation of large plastics has recently become a serious global problem. The major concern with ... [more]

The accumulation of microplastics (MP) in soil via their continuous release and degradation of large plastics has recently become a serious global problem. The major concern with MP is their potential to sorb pollutants as well as ingestion by living organisms. Hence, this study focused on the effect of PVC MP exposure on increasing the risk of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) bioaccumulation in earthworms in addition to their reproduction. In general, the bioaccumulation factor (BAF) for PFOA and PFOS increased up to 200% in earthworms exposed to MP-contaminated soil. MP at 500 and 1000 mg kg -1 soil caused enhanced uptake of PFOS and PFOA in earthworms, and a significant reduction in their reproduction. These results have significant implications for risk assessment of MP in soil.

Nova 2021 Morrissy JG, Currell MJ, Reichman SM, Surapaneni A, Megharaj M, Crosbie ND, et al., 'Nitrogen contamination and bioremediation in groundwater and the environment: A review', Earth-Science Reviews, 222 (2021) [C1]

Nitrogen contamination of groundwater and the environment is an increasing problem in today&apos;s society. Since the invention of the Haber-Bosh process in 1913, the impacts of N... [more]

Nitrogen contamination of groundwater and the environment is an increasing problem in today's society. Since the invention of the Haber-Bosh process in 1913, the impacts of N on human health and the environment have become increasingly widespread due to the industrial scale production of reactive N (Nr). As a result, government organisations and the scientific community continue to make advances towards tackling this ongoing problem. The inherent difficulties of accessing, observing and monitoring groundwater, combined with the complexity of interactions between groundwater chemistry, hydrogeology and ecology have resulted in gaps in fundamental knowledge, specifically regarding the understanding and remediation of N contaminated groundwater. As these knowledge gaps are addressed with ongoing research, current and future remediation targets are being consistently updated; this has resulted in past remediation strategies that may no longer be consistent in meeting new regulatory guidelines for water quality. As such, the search for more technically and economically feasible remediation strategies continues. Recent advances in bioremediation technologies have opened up promising avenues for research in the remediation of N contaminated groundwater. This literature review outlines the past, present and future of Nr-contamination and remediation in Nr -contaminated groundwater within the broader context of the larger environment. The literature cited in this review is critically evaluated to determine significant knowledge gaps.

Nova 2021 Lu G, Tian H, Nurzhan A, Gu X, Liu C, Megharaj M, He W, 'How different are the arsenic fractions inhibit alkaline phosphatases on aggregates scale?', Science of the Total Environment, 774 (2021) [C1]

Arsenate [As(V)], in general, is associated with various aggregates and exists as different species in soil, which in turn influences its toxicity and potential contamination. Pre... [more]

Arsenate [As(V)], in general, is associated with various aggregates and exists as different species in soil, which in turn influences its toxicity and potential contamination. Previous studies have demonstrated the usefulness of alkaline phosphatases (ALP) to evaluate As(V) pollution. However, the effect of different arsenic fractions on ALP among soil aggregates is still unclear. Thus, the distribution of As fractions and ALP kinetics was determined in four-month As-aged paddy soil aggregates. Results revealed the two major fractions of As in aggregates were humic-bound and Fe and Mn oxides-bound [both around 30% under 800 mg kg-1 of As(V)]. Besides, it was observed that available soil phosphorus could positively affect the relative content of water-soluble, exchangeable and carbonate-bound arsenic. In the kinetics experiment, both the Michaelis-Menten constant (Km) and maximum reaction velocity (Vmax) of ALP increased with increasing As(V) concentration under four months ageing for each size aggregate. Multiple linear stepwise regression analysis between kcat and the relative content of arsenic fraction indicated that carbonate-bound arsenic is the main fraction that inhibited the kcat for macroaggregates (> 0.25 mm size). For soil aggregates of 0.1¿0.25 mm size, kcat increased with an increase in arsenic residual fraction. As for aggregates <0.1 mm size, Fe and Mn oxide-bound fraction is the main fraction that inhibited the kcat. Overall, this study suggests carbonate-bound and Fe and Mn oxide-bound arsenic fractions could decrease the ALP activities via a decrease in the catalytic efficiency in macroaggregates and <0.1 mm size aggregates, respectively. Besides, available phosphorus should be considered as the main factor when assessing As biotoxicity and mobility.

Nova 2021 Sivaram AK, Logeshwaran P, Surapaneni A, Shah K, Crosbie N, Rogers Z, et al., 'Evaluation of Cyto-genotoxicity of Perfluorooctane Sulfonate (PFOS) to Allium cepa', ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 40 792-798 (2021) [C1] Nova 2021 Rathnayake IVN, Megharaj M, Beer M, Naidu R, 'Medium composition affects the heavy metal tolerance of microalgae: a comparison', Journal of Applied Phycology, 33 3683-3695 (2021) [C1]

Tolerance of the three metals cadmium (Cd), copper (Cu), and zinc (Zn) by four microalgal species was investigated in three different culture media available in the literature tog... [more]

Tolerance of the three metals cadmium (Cd), copper (Cu), and zinc (Zn) by four microalgal species was investigated in three different culture media available in the literature together with a modified version in order to study the effect of growth media components in estimating the bioavailability of metals introduced into the medium. The free metal content of each medium was also determined using Visual MINTEQ version 3.1 to compare the bioassays. Four microalgal isolates were identified as Desmodesmus sp-I, Desmodesmus sp-II, Coelastrella sp., and Chlorella vulgaris. The present work demonstrated that the microalgal media components have a profound effect on the bioavailability of the metals in the media, so that the bioassay results may vary depending on the growth medium used in the experiments. Furthermore, the free metal contents in each media varied depending on the concentrations of metals added. The tolerance of microalgae evaluated as 50% effective concentration (EC50) of metals differed significantly (p < 0.05) depending on the growth medium used and also varied between the species of the same genus. Desmodesmus sp-I showed high sensitivity to Cd (EC50 0.220 ± 0.011¿mg L-1) and Zn (EC50 0.464 ± 0.065¿mg L-1), whereas Desmodesmus sp-II showed high sensitivity to Cu (EC50 0.098 ± 0.002¿mg L-1) when grown in Test Medium 1 (TM1). The Chlorella vulgaris strain was found to be the most resistant microalga among the four isolates tested in this study. This study has significant implications for the risk assessment of these metals using algal bioassays.

Nova 2021 Abbasi S, Lamb D, Rahman MA, Naidu R, Megharaj M, 'Response of phosphorus sensitive plants to arsenate', Environmental Technology and Innovation, 24 (2021) [C1]

Arsenate (As (V)) is a highly toxic species of arsenic (As) which is also an excellent phosphate analogue. Plant species that are adapted to phosphorus (P) impoverished soil displ... [more]

Arsenate (As (V)) is a highly toxic species of arsenic (As) which is also an excellent phosphate analogue. Plant species that are adapted to phosphorus (P) impoverished soil display a negative response to elevated phosphate due to an inability to downregulate P acquisition. Despite widespread As contamination and shared transport systems for As (V) and P uptake, little to no information is available on the response of P-sensitive plants to As (V). The aim of the study was to investigate the response of P-sensitive plants to As (V). One high (Hakea prostrata R.BR) and one moderate (Banksia seminuda B.Rye) P-sensitive species and one vegetable plant species (Cucumis sativus L.) were grown in nutrient solution containing different As (V) concentrations. Based on EC50 data from nutrient culture, Hakea prostrata was the most sensitive species to As (V) followed by B. seminuda and C. sativus. Critical exogenous concentrations of As that reduced plant growth by 50 % (EC50) in H. prostrata, B. seminuda and C. sativus were respectively 0.64, 0.76 and 1.08 µM for shoot and 0.66, 0.51, 1.07 µM for root. Hakea prostrata had the highest translocation factor (ratio of As concentration in shoot to root) of 0.11, followed by B. seminuda (0.03), and C. sativus (0.01). Plant species with high and moderate P sensitivity were associated with high sensitivity to As (V) exposure and accumulation in shoots. The increased sensitivity has important implications in ecological risk assessment and selection of plant species for rehabilitation. The impacts of As(V) at low P levels in soil solution is needed to inform contaminated site assessment and rehabilitation.

Nova 2021 Abinandan S, Venkateswarlu K, Megharaj M, 'Phenotypic changes in microalgae at acidic pH mediate their tolerance to higher concentrations of transition metals', Current Research in Microbial Sciences, 2 (2021) [C1]

Acclimatory phenotypic response is a common phenomenon in microalgae, particularly during heavy metal stress. It is not clear so far whether acclimating to one abiotic stressor ca... [more]

Acclimatory phenotypic response is a common phenomenon in microalgae, particularly during heavy metal stress. It is not clear so far whether acclimating to one abiotic stressor can alleviate the stress imposed by another abiotic factor. The intent of the present study was to demonstrate the implication of acidic pH in effecting phenotypic changes that facilitate microalgal tolerance to biologically excess concentrations of heavy metals. Two microalgal strains, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, were exposed to biologically excess concentrations of Cu (0.50 and 1.0 mg L¿1), Fe (5 and 10 mg L¿1), Mn (5 and 10 mg L¿1) and Zn (2, 5 and 10 mg L¿1) supplemented to the culture medium at pH 3.5 and 6.7. Chlorophyll autofluorescence and biochemical fingerprinting using FTIR-spectroscopy were used to assess the microalgal strains for phenotypic changes that mediate tolerance to metals. Both the strains responded to acidic pH by effecting differential changes in biochemicals such as carbohydrates, proteins, and lipids. Both the microalgal strains, when acclimated to low pH of 3.5, exhibited an increase in protein (< 2-fold) and lipid (> 1.5-fold). Strain MAS1 grown at pH 3.5 showed a reduction (1.5-fold) in carbohydrates while strain MAS3 exhibited a 17-fold increase in carbohydrates as compared to their growth at pH 6.7. However, lower levels of biologically excess concentrations of the selected transition metals at pH 6.7 unveiled positive or no effect on physiology and biochemistry in microalgal strains, whereas growth with higher metal concentrations at this pH resulted in decreased chlorophyll content. Although the bioavailability of free-metal ions is higher at pH 3.5, as revealed by Visual MINTEQ model, no adverse effect was observed on chlorophyll content in cells grown at pH 3.5 than at pH 6.7. Furthermore, increasing concentrations of Fe, Mn and Zn significantly upregulated the carbohydrate metabolism, but not protein and lipid synthesis, in both strains at pH 3.5 as compared to their growth at pH 6.7. Overall, the impact of pH 3.5 on growth response suggested that acclimation of microalgal strains to acidic pH alleviates metal toxicity by triggering physiological and biochemical changes in microalgae for their survival.

Nova 2021 Abbasi S, Lamb DT, Kader M, Naidu R, Megharaj M, 'The influence of long-term ageing on arsenic ecotoxicity in soil', Journal of Hazardous Materials, 407 (2021) [C1]

The ageing of a contaminant in soil influences the bioavailability and toxicity of environmental pollutants. Yet, despite arsenic (As) being an important terrestrial contaminant, ... [more]

The ageing of a contaminant in soil influences the bioavailability and toxicity of environmental pollutants. Yet, despite arsenic (As) being an important terrestrial contaminant, the effect of As ageing on phytotoxicity has received relatively little research. Research to date has reported predominantly short term (< 0.5 years) experiments. Here, we studied the influence of ageing over 0.25 and 5 years on the phytotoxicity of As (as arsenate) on Cucumis sativus L. (cucumber). The study showed that increasing ageing time of As from 0.25 to 5 years increased the EC10 and EC50 values by 4.0 and 1.76 fold, respectively. The dependence of ageing on soil properties was also examined, although only Freundlich sorption parameters were correlated to the ageing factor (r = 0.68, P = 0.028). Soils with high adsorption capacity also showed the greatest change in toxicity over 5 years. In addition, data was compiled from relevant literature to develop a model for As ecotoxicity. The combined model (n = 54) showed no relationship with pH but was correlated to the oxalate extractable iron content and %clay. Arsenate ecotoxicity (EC50, mg/kg) in the multivariate model was related to oxalate iron content, %clay and ageing time. Thus, the results of this study have significant implications for risk assessment of long-term As contaminated soils.

Nova 2021 Arachchige Chamila Samarasinghe SV, Krishnan K, Aitken RJ, Naidu R, Megharaj M, 'Persistence of the parabens in soil and their potential toxicity to earthworms', ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY, 83 (2021) [C1] Nova 2021 Fang C, Sobhani Z, Zhang D, Zhang X, Gibson CT, Tang Y, et al., 'Capture and characterisation of microplastics printed on paper via laser printer's toners', Chemosphere, 281 (2021) [C1]

Microplastics are among the ubiquitous contaminants in our environment. As emerging contaminants, microplastics are still facing with lots of challenges on the characterisation, i... [more]

Microplastics are among the ubiquitous contaminants in our environment. As emerging contaminants, microplastics are still facing with lots of challenges on the characterisation, including their capture, identification and visualisation, particularly from a complex background. For example, when we print documents using a laser printer, we are printing microplastics onto paper, because the plastics are the main ingredient of the toner powder mixture. Characterisation of these microplastic mixture meets an even more complicated challenge, because plastic's signals might be shielded by other toner powder ingredients such as the pigments, the dyes, the black carbon, and the paper fabrics as well. To solve this challenge, we employ various techniques, including SEM, TEM, XPS, FT-IR, TGA and Raman, to characterise the microplastics printed via the toner powders. Interestingly, we show that Raman can distinguish and visualise the distribution of the microplastics from the complex background of the mixture. We estimate the millions of toner powders, each of which is ~4¿6 µm in size, are printed out per A4 sheet as microplastics. The findings send a strong war