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Hand LH, Marshall SJ, Kuet SF. Building a Conceptual Model for the Environmental Fate of the Fungicide Benzovindiflupyr. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2023; 42:995-1009. [PMID: 36861220 DOI: 10.1002/etc.5603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/17/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Degradation of the fungicide benzovindiflupyr was slow in standard regulatory laboratory studies in soil and aquatic systems, suggesting it is a persistent molecule. However, the conditions in these studies differed significantly from actual environmental conditions, particularly the exclusion of light, which prevents potential contributions from the phototrophic microorganisms that are ubiquitous in both aquatic and terrestrial environments. Higher tier laboratory studies that include a more comprehensive range of degradation processes can more accurately describe environmental fate under field conditions. Indirect aqueous photolysis studies with benzovindiflupyr showed that the photolytic half-life in natural surface water can be as short as 10 days, compared with 94 days in pure buffered water. Inclusion of a light-dark cycle in higher tier aquatic metabolism studies, to include the contribution of phototrophic organisms, reduced the total system half-life from >1 year in dark test systems to as little as 23 days. The relevance of these additional processes was confirmed in an outdoor aquatic microcosm study in which the half-life of benzovindiflupyr was 13-58 days. In laboratory soil degradation studies, the degradation rate of benzovindiflupyr was significantly faster in cores with an undisturbed surface microbiotic crust, incubated in a light-dark cycle (half-life of 35 days), than in regulatory studies with sieved soil in the dark (half-life >1 year). A radiolabeled field study validated these observations, showing residue decline with a half-life of approximately 25 days over the initial 4 weeks. Conceptual models of environmental fate based on standard regulatory studies may be incomplete, and additional higher tier laboratory studies can be valuable in elucidating degradation processes and improving the prediction of persistence under actual use conditions. Environ Toxicol Chem 2023;42:995-1009. © 2023 SETAC.
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Affiliation(s)
- Laurence H Hand
- Product Safety Department, Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom and Northern Ireland
| | - Samantha J Marshall
- Product Safety Department, Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom and Northern Ireland
| | - Sui F Kuet
- Product Safety Department, Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom and Northern Ireland
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Afzal B, Naaz H, Sami N, Yasin D, Khan NJ, Fatma T. Mitigative effect of biosynthesized SeNPs on cyanobacteria under paraquat toxicity. CHEMOSPHERE 2022; 293:133562. [PMID: 35026202 DOI: 10.1016/j.chemosphere.2022.133562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/27/2021] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
Increasing population has resulted in increased food demand. Pesticides like paraquat (PQ) have been used indiscriminately to increase the growth and yield of crops. However, this has adversely affected a wide spectrum of non-target organisms like cyanobacteria that are used as a bio-fertilizer in the rice field. In the present study, biogenic- Gloeocaspa gelatinosa NCCU -430 mediated selenium nanoparticles (SeNPs) were synthesized and characterized using different techniques including UV-Visible spectroscopy, XRD, FTIR, TEM and SEM-EDX for their use as PQ toxicity mitigator in cyanobacterial biofertilizer (Anabaena variabilis NCCU-442). Therefore, a comparative study was performed among control, PQ, SeNPs and SeNPs+PQ to check the efficacy of SeNPs in mitigation of PQ induced toxicity. Supplementation of SeNPs in PQ treated culture enhanced antioxidant enzymes activity i.e., SOD (7.55%), CAT (57.94%), APX (17.45%) and GR (14.72%) as compared to only PQ treated culture. The outcomes of the present study suggested that SeNPs can ameliorate the PQ induced stress that may be used in sustainable rice cultivation needed for filing the gap between requirement and supply.
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Affiliation(s)
- Bushra Afzal
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
| | - Haleema Naaz
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
| | - Neha Sami
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
| | - Durdana Yasin
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
| | - Nida Jamil Khan
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
| | - Tasneem Fatma
- Cyanobacterial Biotechnology Lab, Department of Biosciences, Jamia Millia Islamia, Maulana Mohammad Ali Jauhar Marg, Jamia Nagar, New Delhi, 110025, India.
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Crouzet O, Consentino L, Pétraud JP, Marrauld C, Aguer JP, Bureau S, Le Bourvellec C, Touloumet L, Bérard A. Soil Photosynthetic Microbial Communities Mediate Aggregate Stability: Influence of Cropping Systems and Herbicide Use in an Agricultural Soil. Front Microbiol 2019; 10:1319. [PMID: 31258520 PMCID: PMC6587365 DOI: 10.3389/fmicb.2019.01319] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 05/27/2019] [Indexed: 11/13/2022] Open
Abstract
Edaphic cyanobacteria and algae have been extensively studied in dryland soils because they play key roles in the formation of biological soil crusts and the stabilization of soil surfaces. Yet, in temperate agricultural crop soils, little is understood about the functional significance of indigenous photosynthetic microbial communities for various soil processes. This study investigated how indigenous soil algae and cyanobacteria affected topsoil aggregate stability in cereal cropping systems. Topsoil aggregates from conventional and organic cropping systems were incubated in microcosms under dark or photoperiodic conditions with or without a treatment with an herbicide (isoproturon). Physicochemical parameters (bound exopolysaccharides, organic carbon) and microbial parameters (esterase activity, chlorophyll a biomass, and pigment profiles) were measured for incubated aggregates. Aggregate stability were analyzed on the basis of aggregate size distribution and the mean weight diameter (MWD) index, resulting from disaggregation tests. Soil photosynthetic microbial biomass (chl a) was strongly and positively correlated with aggregate stability indicators. The development of microalgae crusts in photoperiodic conditions induced a strong increase of the largest aggregates (>2 mm), as compared to dark conditions (up to 10.6 fold and 27.1 fold, in soil from organic and conventional cropping systems, respectively). Concomitantly, the MWD significantly increased by 2.4 fold and 4.2 fold, for soil from organic and conventional cropping systems. Soil microalgae may have operated directly via biochemical mechanisms, by producing exopolymeric matrices surrounding soil aggregates (bound exopolysaccharides: 0.39-0.45 μg C g-1 soil), and via biophysical mechanisms, where filamentous living microbiota enmeshed soil aggregates. In addition, they may have acted indirectly by stimulating heterotrophic microbial communities, as revealed by the positive effect of microalgal growth on total microbial activity. The herbicide treatment negatively impacted soil microalgal community, resulting in significant decreases of the MWD of the conventional soil aggregates (up to -42% of the value in light treatment). This study underscores that indigenous edaphic algae and cyanobacteria can promote aggregate formation, by forming photosynthetic microbiotic crusts, thus improving the structural stability of topsoil, in temperate croplands. However, the herbicide uses can impair the functional abilities of algal and cyanobacterial communities in agricultural soils. Originality/Significance Edaphic algal and cyanobacterial communities are known to form photosynthetic microbial crusts in arid soils, where they drive key ecosystem functions. Although less well characterized, such communities are also transiently abundant in temperate and mesic cropped soils. This microcosm study investigated the communities' functional significance in topsoil aggregate formation and stabilization in two temperate cropping systems. Overall, our results showed that the development of indigenous microalgal communities under our experimental conditions drove higher structural stability in topsoil aggregates in temperate cropland soils. Also, herbicide use affected photosynthetic microbial communities and consequently impaired soil aggregation.
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Affiliation(s)
- Olivier Crouzet
- UMR ECOSYS (Ecologie et Ecotoxicologie des Agroécosystèmes), INRA, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Laurent Consentino
- UMR ECOSYS (Ecologie et Ecotoxicologie des Agroécosystèmes), INRA, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Jean-Pierre Pétraud
- UMR ECOSYS (Ecologie et Ecotoxicologie des Agroécosystèmes), INRA, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Christelle Marrauld
- UMR ECOSYS (Ecologie et Ecotoxicologie des Agroécosystèmes), INRA, AgroParisTech, Université Paris-Saclay, Versailles, France
| | | | - Sylvie Bureau
- UMR 408 SQPOV, INRA, Avignon Université, Avignon, France
| | | | - Line Touloumet
- UMR 408 SQPOV, INRA, Avignon Université, Avignon, France
| | - Annette Bérard
- UMR 1114 EMMAH (Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes), INRA, Avignon Université, Avignon, France
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Lu YC, Zhang S, Yang H. Acceleration of the herbicide isoproturon degradation in wheat by glycosyltransferases and salicylic acid. JOURNAL OF HAZARDOUS MATERIALS 2014; 283:806-814. [PMID: 25464323 DOI: 10.1016/j.jhazmat.2014.10.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 09/10/2014] [Accepted: 10/19/2014] [Indexed: 06/04/2023]
Abstract
Isoproturon (IPU) is a herbicide widely used to prevent weeds in cereal production. Due to its extensive use in agriculture, residues of IPU are often detected in soils and crops. Overload of IPU to crops is associated with human health risks. Hence, there is an urgent need to develop an approach to mitigate its accumulation in crops. In this study, the IPU residues and its degradation products in wheat were characterized using ultra performance liquid chromatography-time of fight tandem-mass spectrometer/mass spectrometer (UPLC-TOF-MS/MS). Most detected IPU-derivatives were sugar-conjugated. Degradation and glycosylation of IPU-derivatives could be enhanced by applying salicylic acid (SA). While more sugar-conjugated IPU-derivatives were identified in wheat with SA application, lower levels of IPU were detected, indicating that SA is able to accelerate intracellular IPU catabolism. All structures of IPU-derivatives and sugar-conjugated products were characterized. Comparative data were provided with specific activities and gene expression of certain glucosyltransferases. A pathway with IPU degradation and glucosylation was discussed. Our work indicates that SA-accelerated degradation is practically useful for wheat crops growing in IPU-contaminated soils because such crops with SA application can potentially lower or minimize IPU accumulation in levels below the threshold for adverse effects.
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Affiliation(s)
- Yi Chen Lu
- Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Shuang Zhang
- State key laboratory of food science and technology, Jiangnan University, Wuxi 214122, China
| | - Hong Yang
- Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing 210095, China.
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Davies LO, Bramke I, France E, Marshall S, Oliver R, Nichols C, Schäfer H, Bending GD. Non-UV light influences the degradation rate of crop protection products. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:8229-8237. [PMID: 23819841 DOI: 10.1021/es402139x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Crop protection products (CPPs) are subject to strict regulatory evaluation, including laboratory and field trials, prior to approval for commercial use. Laboratory tests lack environmental realism, while field trials are difficult to control. Addition of environmental complexity to laboratory systems is therefore desirable to mimic a field environment more effectively. We investigated the effect of non-UV light on the degradation of eight CPPs (chlorotoluron, prometryn, cinosulfuron, imidacloprid, lufenuron, propiconazole, fludioxonil, and benzovindiflupyr) by addition of non-UV light to standard OECD 307 guidelines. Time taken for 50% degradation of benzovindiflupyr was halved from 373 to 183 days with the inclusion of light. Similarly, time taken for 90% degradation of chlorotoluron decreased from 79 to 35 days under light conditions. Significant reductions in extractable parent compound occurred under light conditions for prometryn (4%), imidacloprid (8%), and fludioxonil (24%) compared to dark controls. However, a significantly slower rate of cinosulfuron (14%) transformation was observed under light compared to dark conditions. Under light conditions, nonextractable residues were significantly higher for seven of the CPPs. Soil biological and chemical analyses suggest that light stimulates phototroph growth, which may directly and/or indirectly impact CPP degradation rates. The results of this study strongly suggest that light is an important parameter affecting CPP degradation, and inclusion of light into regulatory studies may enhance their environmental realism.
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Affiliation(s)
- Lawrence O Davies
- School of Life Sciences, Gibbet Hill Campus, University of Warwick , Coventry, CV4 7AL, UK.
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Singh DP, Khattar JIS, Kaur M, Kaur G, Gupta M, Singh Y. Anilofos tolerance and its mineralization by the cyanobacterium Synechocystis sp. strain PUPCCC 64. PLoS One 2013; 8:e53445. [PMID: 23382844 PMCID: PMC3561370 DOI: 10.1371/journal.pone.0053445] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 11/28/2012] [Indexed: 11/19/2022] Open
Abstract
This study deals with anilofos tolerance and its mineralization by the common rice field cyanobacterium Synechocystis sp. strain PUPCCC 64. The organism tolerated anilofos up to 25 mg L−1. The herbicide caused inhibitory effects on photosynthetic pigments of the test organism in a dose-dependent manner. The organism exhibited 60, 89, 96, 85 and 79% decrease in chlorophyll a, carotenoids, phycocyanin, allophycocyanin and phycoerythrin, respectively, in 20 mg L−1 anilofos on day six. Activities of superoxide dismutase, catalase and peroxidase increased by 1.04 to 1.80 times over control cultures in presence of 20 mg L−1 anilofos. Glutathione content decreased by 26% while proline content was unaffected by 20 mg L−1 anilofos. The test organism showed intracellular uptake and metabolized the herbicide. Uptake of herbicide by test organism was fast during initial six hours followed by slow uptake until 120 hours. The organism exhibited maximum anilofos removal at 100 mg protein L−1, pH 8.0 and 30°C. Its growth in phosphate deficient basal medium in the presence of anilofos (2.5 mg L−1) indicated that herbicide was used by the strain PUPCCC 64 as a source of phosphate.
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Affiliation(s)
- D P Singh
- Department of Botany, Punjabi University, Patiala, Punjab, India.
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Thomas KA, Hand LH. Assessing the potential for algae and macrophytes to degrade crop protection products in aquatic ecosystems. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2011; 30:622-631. [PMID: 21298708 DOI: 10.1002/etc.412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/29/2010] [Accepted: 09/19/2010] [Indexed: 05/30/2023]
Abstract
Rates of pesticide degradation in aquatic ecosystems often differ between those observed within laboratory studies and field trials. Under field conditions, a number of additional processes may well have a significant role, yet are excluded from standard laboratory studies, for example, metabolism by aquatic plants, phytoplankton, and periphyton. These constituents of natural aquatic ecosystems have been shown to be capable of metabolizing a range of crop protection products. Here we report the rate of degradation of six crop protection products assessed in parallel in three systems, under reproducible, defined laboratory conditions, designed to compare aquatic sediment systems which exclude macrophytes and algae against those in which macrophytes and/or algae are included. All three systems remained as close as possible to the Organisation for Economic Co-operation and Development (OECD) 308 guidelines, assessing degradation of parent compound in the total system in mass balanced studies using ((14) C) labeled compounds. We observed, in all cases where estimated, significant increases in the rate of degradation in both the algae and macrophyte systems when compared to the standard systems. By assessing total system degradation within closed, mass balanced studies, we have shown that rates of degradation are enhanced in water/sediment systems that include macrophytes and algae. The contribution of these communities should therefore be considered if the aquatic fate of pesticides is to be fully understood.
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Affiliation(s)
- Kevin A Thomas
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom
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Hand LH, Oliver RG. The behavior of isopyrazam in aquatic ecosystems: implementation of a tiered investigation. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2010; 29:2702-2712. [PMID: 20891015 DOI: 10.1002/etc.337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/14/2010] [Accepted: 07/26/2010] [Indexed: 05/29/2023]
Abstract
Degradation of a new fungicide, isopyrazam, was slow in water-sediment systems maintained in the dark, with degradation half-life (DegT50) values in the total system (water column and sediment) of greater than one year, and only moderately fast in a photolysis study in buffered pure water (DegT50 > 60 d). This indicated that microbial degradation and direct photolysis are not significant loss mechanisms for this compound. Under more realistic conditions, a number of other processes of natural attenuation occur, such as metabolism by aquatic plants, microalgae, and periphyton and indirect photolysis. A photolysis study in sterile natural water, and water-sediment studies incorporating aquatic macrophytes and microalgae under fluorescent light, were therefore conducted to investigate the contribution of these processes to the fate of isopyrazam. Degradation rates were at least one order of magnitude faster in these higher-tier laboratory studies, indicating that all of these processes may have a role to play in complex natural ecosystems. The fate in an outdoor system, designed to mimic conditions in edge-of-field drainage ditches, also was investigated to provide an integrated picture of the contribution of all the different potential loss mechanisms to the overall fate of isopyrazam. The total system DegT50 in the study was similar to that observed in the higher-tier laboratory studies. Furthermore, the pattern of degradation formation allowed for the contribution of the different degradation processes at work in the microcosm study to be contextualized. The implementation of this tiered approach to investigating the aquatic fate of crop protection products provides a comprehensive explanation of the behavior of isopyrazam and clearly demonstrates that it will not persist in the aquatic environment under natural conditions.
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Affiliation(s)
- Laurence H Hand
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom.
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Katagi T. Bioconcentration, bioaccumulation, and metabolism of pesticides in aquatic organisms. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 204:1-132. [PMID: 19957234 DOI: 10.1007/978-1-4419-1440-8_1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The ecotoxicological assessment of pesticide effects in the aquatic environment should normally be based on a deep knowledge of not only the concentration of pesticides and metabolites found but also on the influence of key abiotic and biotic processes that effect rates of dissipation. Although the bioconcentration and bioaccumulation potentials of pesticides in aquatic organisms are conveniently estimated from their hydrophobicity (represented by log K(ow), it is still indispensable to factor in the effects of key abiotic and biotic processes on such pesticides to gain a more precise understanding of how they may have in the natural environment. Relying only on pesticide hydrophobicity may produce an erroneous environmental impact assessment. Several factors affect rates of pesticide dissipation and accumulation in the aquatic environment. Such factors include the amount and type of sediment present in the water and type of diet available to water-dwelling organisms. The particular physiological behavior profiles of aquatic organisms in water, such as capacity for uptake, metabolism, and elimination, are also compelling factors, as is the chemistry of the water. When evaluating pesticide uptake and bioconcentration processes, it is important to know the amount and nature of bottom sediments present and the propensity that the stuffed aquatic organisms have to absorb and process xenobiotics. Extremely hydrophobic pesticides such as the organochlorines and pyrethroids are susceptible to adsorb strongly to dissolved organic matter associated with bottom sediment. Such absorption reduces the bioavailable fraction of pesticide dissolved in the water column and reduces the probable ecotoxicological impact on aquatic organisms living the water. In contrast, sediment dweller may suffer from higher levels of direct exposure to a pesticide, unless it is rapidly degraded in sediment. Metabolism is important to bioconcentration and bioaccumulation processes, as is detoxification and bioactivation. Hydrophobic pesticides that are expected to be highly stored in tissues would not be bioconcentrated if susceptible to biotic transformation by aquatic organisms to more rapidly metabolized to hydrophilic entities are generally less toxic. By analogy, pesticides that are metabolized to similar entities by aquatic species surely are les ecotoxicologically significant. One feature of fish and other aquatic species that makes them more relevant as targets of environmental studies and of regulation is that they may not only become contaminated by pesticides or other chemicals, but that they constitute and important part of the human diet. In this chapter, we provide an overview of the enzymes that are capable of metabolizing or otherwise assisting in the removal of xenobiotics from aquatic species. Many studies have been performed on the enzymes that are responsible for metabolizing xenobiotics. In addition to the use of conventional biochemical methods, such studies on enzymes are increasingly being conducted using immunochemical methods and amino acid or gene sequences analysis. Such studies have been performed in algae, in some aquatic macrophytes, and in bivalva, but less information is available for other aquatic species such as crustacea, annelids, aquatic insecta, and other species. Although their catabolizing activity is often lower than in mammals, oxidases, especially cytochrome P450 enzymes, play a central role in transforming pesticides in aquatic organisms. Primary metabolites, formed from such initial enzymatic action, are further conjugated with natural components such as carbohydrates, and this aids removal form the organisms. The pesticides that are susceptible to abiotic hydrolysis are generally also biotically degraded by various esterases to from hydrophilic conjugates. Reductive transformation is the main metabolic pathway for organochlorine pesticides, but less information on reductive enzymology processes is available. The information on aquatic species, other than fish, that pertains to bioconcentration factors, metabolism, and elimination is rather limited in the literature. The kinds of basic information that is unavailable but is needed on important aquatic species includes biochemistry, physiology, position in food web, habitat, life cycle, etc. such information is very important to obtaining improved ecotoxicology risk assessments for many pesticides and other chemicals. More research attention on the behavior of pesticides in, and affect on many standard aquatic test species (e.g., daphnids, chironomids, oligochaetes and some bivalves) would particularly be welcome. In addition to improving ecotoxicology risk assessments on target species, such information would also assist in better delineating affects on species at higher trophic levels that are predaceous on the target species. There is also need for designing and employing more realistic approaches to measure bioconcentration and bioaccumulation, and ecotoxicology effects of pesticides in natural environment. The currently employed steady-state laboratory exposure studies are insufficient to deal with the complexity of parameters that control the contrasts to the abiotic processes of pesticide investigated under the strictly controlled conditions, each process is significantly affected in the natural environment not only by the site-specific chemistry of water and sediment but also by climate. From this viewpoint, ecotoxicological assessment should be conducted, together with the detailed analyses of abiotic processes, when higher-tier mesocosm studies are performed. Moreover, in-depth investigation is needed to better understand the relationship between pesticide residues in organisms and associated ecotoxicological endpoints. The usual exposure assessment is based on apparent (nominal) concentrations fo pesticides, and the residues of pesticides or their metabolites in the organisms are not considered in to the context of ecotoxicological endpoints. Therefore, more metabolic and tissue distribution information for terminal pesticide residues is needed for aquatic species both in laboratory settings and in higher-tier (microcosm, mesocosm) studies.
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Affiliation(s)
- Toshiyuki Katagi
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., Takarazuka, Hyogo, 665-8555, Japan.
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Hangler M, Jensen B, Rønhede S, Sørensen SR. Inducible hydroxylation and demethylation of the herbicide isoproturon by Cunninghamella elegans. FEMS Microbiol Lett 2007; 268:254-60. [PMID: 17328751 DOI: 10.1111/j.1574-6968.2006.00599.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
A screening of 27 fungal strains for degradation of the phenylurea herbicide isoproturon was performed and yielded 15 strains capable of converting the herbicide to polar metabolites. The zygomycete fungus Cunninghamella elegans strain JS/2 isolated from an agricultural soil converted isoproturon to several known hydroxylated metabolites. In addition, unknown metabolites were produced in minor amounts. Inducible degradation was indicated by comparing resting cells pregrown with or without isoproturon. This shows that strain JS/2 is capable of partially degrading isoproturon and that one or more of the enzymes involved are inducible upon isoproturon exposure.
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Affiliation(s)
- Martin Hangler
- Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade, Copenhagen K, Denmark
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Böttcher T, Schroll R. The fate of isoproturon in a freshwater microcosm with Lemna minor as a model organism. CHEMOSPHERE 2007; 66:684-9. [PMID: 16963102 DOI: 10.1016/j.chemosphere.2006.07.087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 07/26/2006] [Accepted: 07/27/2006] [Indexed: 05/11/2023]
Abstract
Degradation, bioaccumulation and volatile loss of the 14C-labeled phenylurea herbicide isoproturon (IPU) was examined in a freshwater microcosm with the free floating macrophyte species Lemna minor during a 21-day exposure time. Isoproturon volatilisation was very low with 0.13+/-0.01% of the initially applied herbicide. Only a minor amount of the herbicide was completely metabolised, presumably by rhizosphere microorganisms and released as 14CO2. In total, about 9% isoproturon was removed from the aquatic medium during 21 days. The major portion of the pesticide was removed by bioaccumulation of Lemna minor (5.0+/-0.8%) and the bioconcentration factor (BCF) based on freshweight was 15.8+/-0.2. However, this study indicated a high persistence of IPU in freshwater ecosystems and a potential hazard due to bioaccumulation in non-target species. The novel experimental system of this study, developed for easy use and multiple sampling abilities, enabled quantitatively studying the fate of isoproturon and showed high reproducibility with a mean average (14)C-recovery rate of 97.1+/-0.7%.
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Affiliation(s)
- Thomas Böttcher
- Institute of Soil Ecology, GSF-National Research Center for Environment and Health, Neuherberg, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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Rønhede S, Jensen B, Rosendahl S, Kragelund BB, Juhler RK, Aamand J. Hydroxylation of the herbicide isoproturon by fungi isolated from agricultural soil. Appl Environ Microbiol 2006; 71:7927-32. [PMID: 16332769 PMCID: PMC1317374 DOI: 10.1128/aem.71.12.7927-7932.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several asco-, basidio-, and zygomycetes isolated from an agricultural field were shown to be able to hydroxylate the phenylurea herbicide isoproturon [N-(4-isopropylphenyl)-N',N'-dimethylurea] to N-(4-(2-hydroxy-1-methylethyl)phenyl)-N',N'-dimethylurea and N-(4-(1-hydroxy-1-methylethyl)phenyl)-N',N'-dimethylurea. Bacterial metabolism of isoproturon has previously been shown to proceed by an initial demethylation to N-(4-isopropylphenyl)-N'-methylurea. In soils, however, hydroxylated metabolites have also been detected. In this study we identified fungi as organisms that potentially play a major role in the formation of these hydroxylated metabolites in soils treated with isoproturon. Isolates of Mortierella sp. strain Gr4, Phoma cf. eupyrena Gr61, and Alternaria sp. strain Gr174 hydroxylated isoproturon at the first position of the isopropyl side chain, yielding N-(4-(2-hydroxy-1-methylethyl)phenyl)-N',N'-dimethylurea, while Mucor sp. strain Gr22 hydroxylated the molecule at the second position, yielding N-(4-(1-hydroxy-1-methylethyl)phenyl)-N',N'-dimethylurea. Hydroxylation was the dominant mode of isoproturon transformation in these fungi, although some cultures also produced traces of the N-demethylated metabolite N-(4-isopropylphenyl)-N'-methylurea. A basidiomycete isolate produced a mixture of the two hydroxylated and N-demethylated metabolites at low concentrations. Clonostachys sp. strain Gr141 and putative Tetracladium sp. strain Gr57 did not hydroxylate isoproturon but N demethylated the compound to a minor extent. Mortierella sp. strain Gr4 also produced N-(4-(2-hydroxy-1-methylethyl)phenyl)-N'-methylurea, which is the product resulting from combined N demethylation and hydroxylation.
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Affiliation(s)
- Stig Rønhede
- Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
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Novák J, Vlasáková V, Tykva R, Ruml T. Degradation of juvenile hormone analog by soil microbial isolates. CHEMOSPHERE 2003; 52:151-159. [PMID: 12729698 DOI: 10.1016/s0045-6535(03)00221-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Juvenoids are efficient pesticides with relatively low toxicity to humans. However, few studies have evaluated the effect of degradation by soil microorganisms on their toxicity. The effects of bacterial, fungal and yeast isolates on aerobic decomposition of ethyl N-[2-[4-(2,2-ethylenedioxy-1-cyclohexylmethyl)phenoxy]ethyl] carbamate during eight weeks were determined. The effect of different concentration of glucose on their degradation activity is also analyzed.
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Affiliation(s)
- Jaroslav Novák
- Department of Biochemistry and Microbiology, Institute of Chemical Technology, Technická 5, 166 28, 6, Prague, Czech Republic
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Mostafa FIY, Helling CS. Impact of four pesticides on the growth and metabolic activities of two photosynthetic algae. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2002; 37:417-444. [PMID: 12369760 DOI: 10.1081/pfc-120014873] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The acute toxicity was determined for soil algae Chlorella kesslerei and Anabaena inaequalis, exposed to pesticides lindane, pentachlorophenol (PCP), isoproturon (IPU), and methyl parathion (MP). Toxicity markers included growth inhibition, chlorophyll biosynthesis, and total carbohydrate content, as a function of dose and time. Concentration response functions (EC50) were estimated by probit data transformation and weighted linear regression analyses. Lindane's toxicity to Chlorella increased sharply with time (EC50 = 7490, 10.3, 0.09 mg L(-1); 24, 48, 72 h), but remained nearly constant through 72 h with Anabaena (8.7-6.7 mg L(-1); 24-72 h). PCP at low concentrations stimulated algal growth and chlorophyll a production, an effect reversed at higher doses. Anabaena was less tolerant of PCP and MP than was Chlorella. The 96-h static EC50 values for Chlorella were: 0.003, 34, 0.05, and 291 mg L(-1) for lindane, PCP, isoproturon, and MP, respectively; for Anabaena, these were 4.2, 0.13, 0.21, and 19 mg L(-1). Carbohydrate production responses were similar to those of cell density (growth) and chlorophyll biosynthesis, with MP having the lowest adverse impact. The overall relative toxicity among the four tested pesticides was: for Chlorella, lindane > IPU >> PCP >> MP; and for Anabaena, PCP > IPU > lindane > MP. The results confirm that toxicants such as these pesticides may affect individual (though related) species to significantly different degrees.
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Affiliation(s)
- Fadwa I Y Mostafa
- Plant Sciences Inst., Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
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