The Experts below are selected from a list of 5142 Experts worldwide ranked by ideXlab platform
Jens Aamand - One of the best experts on this subject based on the ideXlab platform.
-
Mineralization of hydroxylated Isoproturon metabolites produced by fungi
Soil Biology and Biochemistry, 2007Co-Authors: Stig Rønhede, Sebastian R. Sørensen, Bo Boye Busk Jensen, Jens AamandAbstract:Abstract When exposed to the herbicide Isoproturon, some soil fungi in pure culture metabolize the substance to hydroxylated metabolites. Hydroxylated metabolites of Isoproturon have also been detected in soil studies. In an agricultural soil not previously exposed to Isoproturon we found that the hydroxylated Isoproturon metabolite N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea mineralized faster than both Isoproturon and its N-demethylated metabolite N-(4-isopropylphenyl)-N′-methylurea (MDIPU), thus indicating that mineralization of Isoproturon is stimulated by fungal hydroxylation in this soil. In soils previously treated with Isoproturon, in contrast, Isoproturon and both its hydroxylated and demethylated metabolites mineralized at almost the same rate with up to 52% of the 14C-ring-carbon being degraded to 14CO2 within 63 days. Thus hydroxylated metabolites of Isoproturon do not seem to be more persistent than Isoproturon, and hence may degrade before they can leach from topsoil and contaminate the aquatic environment. While an Isoproturon-mineralizing bacterium Sphingomonas sp. SRS2 and a MDIPU-mineralizing mixed bacterial culture were able to deplete the medium of hydroxylated metabolites, little or no mineralization took place. This indicates that other bacteria must be present in the soil that are able to benefit from Isoproturon being made available to mineralization by fungal hydroxylation.
-
hydroxylation of the herbicide Isoproturon by fungi isolated from agricultural soil
Applied and Environmental Microbiology, 2005Co-Authors: Stig Rønhede, Bo Boye Busk Jensen, Soren Rosendahl, Birthe B Kragelund, Rene K Juhler, Jens AamandAbstract: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-(2hydroxy-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.
-
Rapid mineralisation of the herbicide Isoproturon in soil from a previously treated Danish agricultural field.
Pest management science, 2003Co-Authors: Sebastian R. Sørensen, Jens AamandAbstract:MineralisationofthephenylureaherbicideIsoproturon(3-(4-isopropylphenyl)-1,1-dimethylurea) and two of its known metabolites, 3-(4-isopropylphenyl)-1-methylurea (monodesmethyl-Isoproturon) and 4-isopropylaniline, was studied in Danish agricultural soils with or without previous exposure to isopro- turon. A potential for rapid mineralisation of Isoproturon and the two metabolites was present in soils sampled from three plots within an agricultural field previously treated regularly with the herbicide, with 34-45%, 51-58% and 33-36% of the added (phenyl-U- 14 C)Isoproturon, (phenyl-U- 14 C)monodesmethyl- Isoproturon and (phenyl-U- 14 C)4-isopropylaniline metabolised to ( 14 C)carbon dioxide within 30days at 20 ◦ C. In contrast, such extensive mineralisation of these three compounds was not observed within this period in soils sampled from two other agricultural fields without previous treatment with Isoproturon. The mineralisation patterns indicated growth-linked metabolism of the three compounds in the previously exposed soils, and doubling times for ( 14 C)carbon dioxide production ranged from 1.6 to 3.2, 1.0 to 2.1 and 1.3 to 1.7days for Isoproturon, monodesmethyl-Isoproturon and 4-isopropylaniline, respectively. The ability to mineralise (phenyl-U- 14 C)Isoproturon to ( 14 C)carbon dioxide was successfully sub-cultured to a fresh mineral medium which provided Isoproturon as sole source of carbon and nitrogen. One of the soils sampled from an agricultural field not previously treated with Isoproturon showed accelerated mineralisation of (phenyl-U- 14 C)4-isopropylaniline toward the end of the experiment, with a doubling time for ( 14 C)carbon dioxide production of 7.4days. This study indicates that the occurrence of rapid mineralisation of the phenyl ring of Isoproturon to carbon dioxide is related to previous exposure to the herbicide, which suggests that microbial adaptation upon repeated Isoproturon use may occur within agricultural fields. 2003 Society of Chemical Industry
-
Mineralization of soil-aged Isoproturon and Isoproturon metabolites by Sphingomonas sp. strain SRS2.
Journal of environmental quality, 2003Co-Authors: Helle Johannesen, Sebastian R. Sørensen, Jens AamandAbstract:The aim of the study was to determine the effect of aging of the herbicide Isoproturon and its metabolites monodesmethyl-Isoproturon and 4-isopropyl-aniline in agricultural soil on their availability to the degrading bacterium Sphingomonas sp. strain SRS2. The 14C-ring-labeled Isoproturon, monodesmethyl-Isoproturon, and 4-isopropyl-aniline were added to sterilized soil and stored for 1, 49, 71, or 131 d before inoculation with strain SRS2. The availability of the compounds was estimated from the initial mineralization and the amount of 14CO2 recovered after 120 d of incubation. Aging in soil for 131 d reduced the initial mineralization of Isoproturon and monodesmethyl-Isoproturon and, in the case of Isoproturon, also reduced the recovery of 14CO2. Initial mineralization and recovery of 14CO2 from aged 4-isopropyl-aniline were slightly reduced, but less 14CO2 was generally produced than with Isoproturon or monodesmethyl-Isoproturon. Thus, recovery of 14CO2 from 14C-Isoproturon and 14C-monodesmethyl-Isoproturon was 50.7 to 64.4% of the initially added 14C, while recovery from 14C-4-isopropyl-aniline was only 11.7 to 17.0%. Sorption measurements revealed similar Freundlich constants (K(f)) for Isoproturon and monodesmethyl-Isoproturon, whereas K(f) for 4-isopropyl-aniline was more than fivefold greater. The findings imply that in soil, partial degradation of Isoproturon to 4-isopropyl-aniline may lead to reduced mineralization of the herbicide due to sorption of the aniline moiety.
-
growth in coculture stimulates metabolism of the phenylurea herbicide Isoproturon by sphingomonas sp strain srs2
Applied and Environmental Microbiology, 2002Co-Authors: Sebastian R. Sørensen, Zeev Ronen, Jens AamandAbstract:Metabolism of the phenylurea herbicide Isoproturon by Sphingomonas sp. strain SRS2 was significantly enhanced when the strain was grown in coculture with a soil bacterium (designated strain SRS1). Both members of this consortium were isolated from a highly enriched Isoproturon-degrading culture derived from an agricultural soil previously treated regularly with the herbicide. Based on analysis of the 16S rRNA gene, strain SRS1 was assigned to the β-subdivision of the proteobacteria and probably represents a new genus. Strain SRS1 was unable to degrade either Isoproturon or its known metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, or 4-isopropyl-aniline. Pure culture studies indicate that Sphingomonas sp. SRS2 is auxotrophic and requires components supplied by association with other soil bacteria. A specific mixture of amino acids appeared to meet these requirements, and it was shown that methionine was essential for Sphingomonas sp. SRS2. This suggests that strain SRS1 supplies amino acids to Sphingomonas sp. SRS2, thereby leading to rapid metabolism of 14C-labeled Isoproturon to 14CO2 and corresponding growth of strain SRS2. Proliferation of strain SRS1 suggests that Isoproturon metabolism by Sphingomonas sp. SRS2 provides unknown metabolites or cell debris that supports growth of strain SRS1. The role of strain SRS1 in the consortium was not ubiquitous among soil bacteria; however, the indigenous soil microflora and some strains from culture collections also stimulate Isoproturon metabolism by Sphingomonas sp. strain SRS2 to a similar extent.
Sebastian R. Sørensen - One of the best experts on this subject based on the ideXlab platform.
-
Inducible hydroxylation and demethylation of the herbicide Isoproturon by Cunninghamella elegans.
FEMS microbiology letters, 2007Co-Authors: Martin Hangler, Bo Boye Busk Jensen, Stig Rønhede, Sebastian R. SørensenAbstract: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.
-
Mineralization of hydroxylated Isoproturon metabolites produced by fungi
Soil Biology and Biochemistry, 2007Co-Authors: Stig Rønhede, Sebastian R. Sørensen, Bo Boye Busk Jensen, Jens AamandAbstract:Abstract When exposed to the herbicide Isoproturon, some soil fungi in pure culture metabolize the substance to hydroxylated metabolites. Hydroxylated metabolites of Isoproturon have also been detected in soil studies. In an agricultural soil not previously exposed to Isoproturon we found that the hydroxylated Isoproturon metabolite N-(4-(2-hydroxy-1-methylethyl)phenyl)-N′,N′-dimethylurea mineralized faster than both Isoproturon and its N-demethylated metabolite N-(4-isopropylphenyl)-N′-methylurea (MDIPU), thus indicating that mineralization of Isoproturon is stimulated by fungal hydroxylation in this soil. In soils previously treated with Isoproturon, in contrast, Isoproturon and both its hydroxylated and demethylated metabolites mineralized at almost the same rate with up to 52% of the 14C-ring-carbon being degraded to 14CO2 within 63 days. Thus hydroxylated metabolites of Isoproturon do not seem to be more persistent than Isoproturon, and hence may degrade before they can leach from topsoil and contaminate the aquatic environment. While an Isoproturon-mineralizing bacterium Sphingomonas sp. SRS2 and a MDIPU-mineralizing mixed bacterial culture were able to deplete the medium of hydroxylated metabolites, little or no mineralization took place. This indicates that other bacteria must be present in the soil that are able to benefit from Isoproturon being made available to mineralization by fungal hydroxylation.
-
Rapid mineralisation of the herbicide Isoproturon in soil from a previously treated Danish agricultural field.
Pest management science, 2003Co-Authors: Sebastian R. Sørensen, Jens AamandAbstract:MineralisationofthephenylureaherbicideIsoproturon(3-(4-isopropylphenyl)-1,1-dimethylurea) and two of its known metabolites, 3-(4-isopropylphenyl)-1-methylurea (monodesmethyl-Isoproturon) and 4-isopropylaniline, was studied in Danish agricultural soils with or without previous exposure to isopro- turon. A potential for rapid mineralisation of Isoproturon and the two metabolites was present in soils sampled from three plots within an agricultural field previously treated regularly with the herbicide, with 34-45%, 51-58% and 33-36% of the added (phenyl-U- 14 C)Isoproturon, (phenyl-U- 14 C)monodesmethyl- Isoproturon and (phenyl-U- 14 C)4-isopropylaniline metabolised to ( 14 C)carbon dioxide within 30days at 20 ◦ C. In contrast, such extensive mineralisation of these three compounds was not observed within this period in soils sampled from two other agricultural fields without previous treatment with Isoproturon. The mineralisation patterns indicated growth-linked metabolism of the three compounds in the previously exposed soils, and doubling times for ( 14 C)carbon dioxide production ranged from 1.6 to 3.2, 1.0 to 2.1 and 1.3 to 1.7days for Isoproturon, monodesmethyl-Isoproturon and 4-isopropylaniline, respectively. The ability to mineralise (phenyl-U- 14 C)Isoproturon to ( 14 C)carbon dioxide was successfully sub-cultured to a fresh mineral medium which provided Isoproturon as sole source of carbon and nitrogen. One of the soils sampled from an agricultural field not previously treated with Isoproturon showed accelerated mineralisation of (phenyl-U- 14 C)4-isopropylaniline toward the end of the experiment, with a doubling time for ( 14 C)carbon dioxide production of 7.4days. This study indicates that the occurrence of rapid mineralisation of the phenyl ring of Isoproturon to carbon dioxide is related to previous exposure to the herbicide, which suggests that microbial adaptation upon repeated Isoproturon use may occur within agricultural fields. 2003 Society of Chemical Industry
-
Mineralization of soil-aged Isoproturon and Isoproturon metabolites by Sphingomonas sp. strain SRS2.
Journal of environmental quality, 2003Co-Authors: Helle Johannesen, Sebastian R. Sørensen, Jens AamandAbstract:The aim of the study was to determine the effect of aging of the herbicide Isoproturon and its metabolites monodesmethyl-Isoproturon and 4-isopropyl-aniline in agricultural soil on their availability to the degrading bacterium Sphingomonas sp. strain SRS2. The 14C-ring-labeled Isoproturon, monodesmethyl-Isoproturon, and 4-isopropyl-aniline were added to sterilized soil and stored for 1, 49, 71, or 131 d before inoculation with strain SRS2. The availability of the compounds was estimated from the initial mineralization and the amount of 14CO2 recovered after 120 d of incubation. Aging in soil for 131 d reduced the initial mineralization of Isoproturon and monodesmethyl-Isoproturon and, in the case of Isoproturon, also reduced the recovery of 14CO2. Initial mineralization and recovery of 14CO2 from aged 4-isopropyl-aniline were slightly reduced, but less 14CO2 was generally produced than with Isoproturon or monodesmethyl-Isoproturon. Thus, recovery of 14CO2 from 14C-Isoproturon and 14C-monodesmethyl-Isoproturon was 50.7 to 64.4% of the initially added 14C, while recovery from 14C-4-isopropyl-aniline was only 11.7 to 17.0%. Sorption measurements revealed similar Freundlich constants (K(f)) for Isoproturon and monodesmethyl-Isoproturon, whereas K(f) for 4-isopropyl-aniline was more than fivefold greater. The findings imply that in soil, partial degradation of Isoproturon to 4-isopropyl-aniline may lead to reduced mineralization of the herbicide due to sorption of the aniline moiety.
-
growth in coculture stimulates metabolism of the phenylurea herbicide Isoproturon by sphingomonas sp strain srs2
Applied and Environmental Microbiology, 2002Co-Authors: Sebastian R. Sørensen, Zeev Ronen, Jens AamandAbstract:Metabolism of the phenylurea herbicide Isoproturon by Sphingomonas sp. strain SRS2 was significantly enhanced when the strain was grown in coculture with a soil bacterium (designated strain SRS1). Both members of this consortium were isolated from a highly enriched Isoproturon-degrading culture derived from an agricultural soil previously treated regularly with the herbicide. Based on analysis of the 16S rRNA gene, strain SRS1 was assigned to the β-subdivision of the proteobacteria and probably represents a new genus. Strain SRS1 was unable to degrade either Isoproturon or its known metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, or 4-isopropyl-aniline. Pure culture studies indicate that Sphingomonas sp. SRS2 is auxotrophic and requires components supplied by association with other soil bacteria. A specific mixture of amino acids appeared to meet these requirements, and it was shown that methionine was essential for Sphingomonas sp. SRS2. This suggests that strain SRS1 supplies amino acids to Sphingomonas sp. SRS2, thereby leading to rapid metabolism of 14C-labeled Isoproturon to 14CO2 and corresponding growth of strain SRS2. Proliferation of strain SRS1 suggests that Isoproturon metabolism by Sphingomonas sp. SRS2 provides unknown metabolites or cell debris that supports growth of strain SRS1. The role of strain SRS1 in the consortium was not ubiquitous among soil bacteria; however, the indigenous soil microflora and some strains from culture collections also stimulate Isoproturon metabolism by Sphingomonas sp. strain SRS2 to a similar extent.
Fabrice Martinlaurent - One of the best experts on this subject based on the ideXlab platform.
-
mapping field spatial distribution patterns of Isoproturon mineralizing activity over a three year winter wheat rape seed barley rotation
Chemosphere, 2013Co-Authors: Sajjad Hussain, Marion Deverslamrani, Ayme Spor, Nadine Rouard, M Porcherot, Jeremie Beguet, Fabrice MartinlaurentAbstract:The temporal and spatial variability of the activity of soil microorganisms able to mineralize the herbicide Isoproturon (IPU) pesticide was investigated over a three-year long crop rotation between 2008 and 2010. Isoproturon mineralization was higher in 2008, when winter wheat was treated with this herbicide, than in 2009 and 2010, when rape seed and barley were treated with different herbicides. Under laboratory conditions, we showed that Isoproturon mineralization was not promoted by sulfonylurea herbicide applied on barley crop in 2010. IPU mineralization was shown to be highly variable at the field scale in years 2009 and 2010. Principal component analyses and analyses of similarities revealed that soil pH and equivalent humidity, and to a lesser extent soil organic matter content and cation exchange capacity (CEC) were the main drivers of Isoproturon-mineralizing activity variance. Using a rather simple model that yields the rate of Isoproturon mineralization as a function of soil pH and equivalent humidity, we explained up to 85% of the variance observed. Mapping field-scale distribution of Isoproturon mineralization over the three-year survey indicated higher variability in 2009 and in 2010 as compared to 2008, suggesting that Isoproturon treatment applied to winter wheat promoted Isoproturon mineralization activity and reduced its spatial variability. Field-scale distribution of Isoproturon mineralization showed important similarity to the distribution of soil pH, equivalent humidity and to a lesser extent to soil organic matter and cation exchange capacity (CEC) thereby confirming our model.
-
spatial variability of Isoproturon mineralizing activity within an agricultural field geostatistical analysis of simple physicochemical and microbiological soil parameters
Environmental Pollution, 2007Co-Authors: El T Sebai, Guy Soulas, Bernard Lagacherie, Fabrice MartinlaurentAbstract:We assessed the spatial variability of Isoproturon mineralization in relation to that of physicochemical and biological parameters in fifty soil samples regularly collected along a sampling grid delimited across a 0.36 ha field plot (40 x 90 m). Only faint relationships were observed between Isoproturon mineralization and the soil pH, microbial C biomass, and organic nitrogen. Considerable spatial variability was observed for six of the nine parameters tested (Isoproturon mineralization rates, organic nitrogen, genetic structure of the microbial communities, soil pH, microbial biomass and equivalent humidity). The map of Isoproturon mineralization rates distribution was similar to that of soil pH, microbial biomass, and organic nitrogen but different from those of structure of the microbial communities and equivalent humidity. Geostatistics revealed that the spatial heterogeneity in the rate of degradation of Isoproturon corresponded to that of soil pH and microbial biomass.
Andrew C. Johnson - One of the best experts on this subject based on the ideXlab platform.
-
The role of microbial community composition and groundwater chemistry in determining Isoproturon degradation potential in UK aquifers.
FEMS Microbiology Ecology, 2004Co-Authors: Andrew C. Johnson, Neville R. Llewellyn, A. K. Lilley, Andrew C. Singer, Christopher J Van Der Gast, Jennifer A Smith, Ian P. ThompsonAbstract:The community response of indigenous sandstone, chalk and limestone groundwater microorganisms to the addition of the commonly used herbicide Isoproturon was examined. The addition of 100 μg l−1 Isoproturon generally caused an increase in species diversity determined by chemotaxonomic analysis (fatty methyl ester analysis) of isolates resulting from incubation of cultures at 18 °C for 4 days. Amongst the groundwater samples to which Isoproturon was added, Isoproturon degradation rates were correlated with increasing dominance of a few species. However, the changes in community profile associated with Isoproturon degradation varied from site to site. Repeated sub-culturing with 100 μg l−1 Isoproturon and sterile groundwater was carried out to examine whether this level of pesticide could exert a selection pressure, and hence stimulate more rapid degradation. Significantly increased degradation was observed in a groundwater sample from the chalk, but not in sandstone, or limestone samples. The addition of filter-sterilised sandstone groundwater to bacteria on filter paper from slow degrading limestone sites significantly improved their degrading performance. The addition of filter-sterilised limestone groundwater to the sandstone bacteria reduced their degradation rate only slightly. The data suggested that the nature of the indigenous community does influence pesticide degradation in groundwater, but that the groundwater chemistry may also play a role.
-
The role of microbial community composition and groundwater chemistry in determining Isoproturon degradation potential in UK aquifers.
FEMS microbiology ecology, 2004Co-Authors: Andrew C. Johnson, Neville R. Llewellyn, A. K. Lilley, Andrew C. Singer, Jennifer A Smith, Christopher J. Van Der Gast, Ian P. ThompsonAbstract:The community response of indigenous sandstone, chalk and limestone groundwater microorganisms to the addition of the commonly used herbicide Isoproturon was examined. The addition of 100 microg l(-1) Isoproturon generally caused an increase in species diversity determined by chemotaxonomic analysis (fatty methyl ester analysis) of isolates resulting from incubation of cultures at 18 degrees C for 4 days. Amongst the groundwater samples to which Isoproturon was added, Isoproturon degradation rates were correlated with increasing dominance of a few species. However, the changes in community profile associated with Isoproturon degradation varied from site to site. Repeated sub-culturing with 100 microg l(-1) Isoproturon and sterile groundwater was carried out to examine whether this level of pesticide could exert a selection pressure, and hence stimulate more rapid degradation. Significantly increased degradation was observed in a groundwater sample from the chalk, but not in sandstone, or limestone samples. The addition of filter-sterilised sandstone groundwater to bacteria on filter paper from slow degrading limestone sites significantly improved their degrading performance. The addition of filter-sterilised limestone groundwater to the sandstone bacteria reduced their degradation rate only slightly. The data suggested that the nature of the indigenous community does influence pesticide degradation in groundwater, but that the groundwater chemistry may also play a role.
-
Potential for Isoproturon, atrazine and mecoprop to be degraded within a chalk aquifer system
Journal of Contaminant Hydrology, 2000Co-Authors: Andrew C. Johnson, Craig White, C Lal BhardwajAbstract:Abstract The potential for herbicide degradation in an unconfined chalk aquifer was examined by collecting and spiking fresh samples and incubating them in the laboratory. The microcosms were incubated at 20°C under aerobic conditions and spiked with either Isoproturon, atrazine or mecoprop at a concentration of 100 μg/l. The samples were obtained from a single fieldsite within the Upper Chalk aquifer in Hampshire, UK. Groundwater samples required the presence of sterile chalk in a ratio of at least 1:13 to promote Isoproturon degradation. An Isoproturon degradation potential existed in the soil, and the chalk unsaturated and saturated zones. However, no degradation of Isoproturon in the unsaturated zone was observed when a more appropriate simulation of in-situ moisture conditions was carried out. Apart from the soil, no potential for atrazine or mecoprop degradation could be detected in the same samples over a 200-day incubation. In a series of groundwater samples taken from different boreholes, 10–300 m apart, large differences in Isoproturon degradation potential were observed. Removal rates for 100 μg/l Isoproturon varied from 83–425 ng/day, but in some samples no degradation potential could be detected. The primary metabolite which could be distinguished from Isoproturon degradation in chalk and groundwater was monodesmethyl–Isoproturon. When a chalk groundwater sample was spiked with Isoproturon at 0.9 μg/l, this was not degraded over a 300-day incubation period. Further experiments with fresh groundwater from a Triassic Sandstone site illustrated that groundwater bacteria could degrade Isoproturon at the more realistic temperature of 10°C as well as at 20°C.
-
The transport and behaviour of Isoproturon in unsaturated chalk cores
Journal of Contaminant Hydrology, 2000Co-Authors: Tim Besien, Richard J. Williams, Andrew C. JohnsonAbstract:A batch sorption study, a microcosm degradation study, and two separate column leaching studies were used to investigate the transport and fate of Isoproturon in unsaturated chalk. The column leaching studies used undisturbed core material obtained from the field by dry percussion drilling. Each column leaching study used 25 cm long, 10 cm wide unsaturated chalk cores through which a pulse of Isoproturon and bromide was eluted. The cores were set-up to simulate conditions in the unsaturated zone of the UK Chalk aquifer by applying a suction of 1 kPa (0.1 m H2O) to the base of each column, and eluting at a rate corresponding to an average recharge rate through the unsaturated Chalk. A dye tracer indicated that the flow was through the matrix under these conditions. The results from the first column study showed high recovery rates for both Isoproturon (73–92%) and bromide (93–96%), and that Isoproturon was retarded by a factor of about 1.23 relative to bromide. In the second column study, two of the four columns were eluted with non-sterile groundwater in place of the sterile groundwater used on all other columns, and this study showed high recovery rates for bromide (85–92%) and lower recovery rates for Isoproturon (66–79% — sterile groundwater, 48–61% — non-sterile groundwater). The enhanced degradation in the columns eluted with non-sterile groundwater indicated that groundwater microorganisms had increased the degradation rate within these columns. Overall, the reduced Isoproturon recovery in the second column study was attributed to increased microbial degradation as a result of the longer study duration (162 vs. 105 days). The breakthrough curves (BTCs) for bromide had a characteristic convection–dispersion shape and were accurately simulated with the minimum of calibration using a simple convection–dispersion model (LEACHP). However, the Isoproturon BTCs had an unusual shape and could not be accurately simulated.
-
Potential for aerobic Isoproturon biodegradation and sorption in the unsaturated and saturated zones of a chalk aquifer
Journal of Contaminant Hydrology, 1998Co-Authors: Andrew C. Johnson, Clare D Hughes, Richard J. Williams, P. John ChiltonAbstract:The potential fate and behaviour of the herbicide Isoproturon, under aerobic conditions, was studied in soil, chalk and groundwater from two sites on an unconfined aquifer in Hampshire, UK. A small but significant sorption potential for Isoproturon was noted in the upper chalk, suggesting that some retardation would take place in transport through the chalk. The degradation potential of the samples was studied using laboratory microcosms. Very little degradation potential appeared to exist for Isoproturon in the unsaturated zone of upper chalk 3 m below the soil surface. Wide variations in degradation rates between samples from the same depth was noted. A degradation potential was noted in the chalk from shallow depths under laboratory microcosm conditions at a pesticide concentration of 100 μg l−1. Of the two sites examined, the most rapid and consistent degradation observed was associated with the groundwater rather than the chalk in the saturated zone. No significant Isoproturon ring mineralisation occurred in the chalk or groundwater samples, implying that where Isoproturon degradation does occur a by-product containing the phenyl ring will persist. Isoproturon degradation potential was not directly related to the moisture content, total organic carbon, ability to metabolise acetate, or number of viable bacteria present in the sample.
Hong Yang - One of the best experts on this subject based on the ideXlab platform.
-
Jasmonic Acids Facilitate the Degradation and Detoxification of Herbicide Isoproturon Residues in Wheat Crops (Triticum aestivum)
2018Co-Authors: Shu Hao Zhang, Jing Jing Zhang, Ai Ping Zhang, Xin Qiang Wang, Hong YangAbstract:Jasmonic acid (JA) [or methyl-jasmonic acid (MeJA)] is one of the important regulators of plant growth, development, and defense with respect to environmental stresses, but how JA is involved in mediation of pesticide accumulation and degradation in plants is largely unknown. This study investigated the contribution of MeJA to detoxification and degradation of Isoproturon (IPU) residues in wheat (Triticum aestivum). Wheat plants were exposed to 4 mg of Isoproturon kg–1 (environmentally realistic concentration). The level of growth and chlorophyll concentration were reduced, while the electrolyte permeability in plants was enhanced. When plants were sprayed with 0.1 μM MeJA, the phytotoxicity induced by Isoproturon was significantly assuaged, which was manifested by an increased chlorophyll concentration and a reduced level of cellular damage in wheat. Activities of several stress marker enzymes with Isoproturon were repressed in the presence of MeJA. We measured accumulation of Isoproturon in wheat and its residues in soil by high-performance liquid chromatography. The concentration of Isoproturon in wheat and soils with MeJA was drastically reduced. Using ultraperformance liquid chromatography–tandem mass spectrometry, 12 Isoproturon derivatives (eight metabolites and four conjugates) in wheat were characterized. We further provided evidence that the concentration of endogenous MeJA was significantly increased in IPU-exposed plants. These results suggest that MeJA was able to detoxify or degrade Isoproturon in wheat when grown in a realistic environmental Isoproturon-polluted soil
-
Toxicology of Isoproturon to the food crop wheat as affected by salicylic acid.
Environmental science and pollution research international, 2012Co-Authors: Lu Liang, Hong YangAbstract:Purpose Isoproturon, a herbicide belonging to the phenylurea family, is widely used to kill weeds in soils. Recent study indicated that Isoproturon has become a contaminant in ecosystems due to its intensive use, thus bringing environmental risks to crop production safety. Salicylic acid (SA) is one of the components in plant defense signaling pathways and regulates diverse physiological responses to biotic and environmental stresses. The purpose of the study is to help to understand how SA mediates the biological process in wheat under Isoproturon stress.
-
impact of low molecular weight organic acids and dissolved organic matter on sorption and mobility of Isoproturon in two soils
Journal of Hazardous Materials, 2011Co-Authors: Qing Ding, Li Juan Guo, Kai Liu, Hui Min Gao, Hong YangAbstract:Isoproturon is a selective herbicide belonging to the phenylurea family and widely used for pre- and post-emergence control of annual weeds. Soil amendments (e.g. organic compounds or dissolved organic matter) may affect environmental behavior and bioavailability of pesticides. However, whether the physiochemical process of Isoproturon in soils is affected by organic amendments and how it is affected in different soil types are unknown. To evaluate the impact of low molecular weight organic acids (LMWOA) and dissolved organic matter (DOM) on sorption/desorption and mobility of Isoproturon in soils, comprehensive analyses were performed using two distinct soil types (Eutric gleysols and Hap udic cambisols). Our analysis revealed that adsorption of Isoproturon in Eutric gleysols was depressed, and desorption and mobility of Isoproturon were promoted in the presence of DOM and LMWOA. However, the opposite result was observed with Hap udic cambisols, suggesting that the soil type affected predominantly the physiochemical process. We also characterized differential components of the soils using three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform infrared (FT-IR) spectroscopy and show that the two soils displayed different intensity of absorption bands for several functional groups.
-
Toxic reactivity of wheat (Triticum aestivum) plants to herbicide Isoproturon.
Journal of agricultural and food chemistry, 2008Co-Authors: Xiao Le Yin, Lei Jiang, Ning Hui Song, Hong YangAbstract:The herbicide Isoproturon is widely used for controlling weed/grass in agricultural practice. However, the side effect of Isoproturon as contaminants on crops is unknown. In this study, we investigated Isoproturon-induced oxidative stress in wheat (Triticum aestivum). The plants were grown in soils with Isoproturon at 0−20 mg/kg and showed negative biological responses. The growth of wheat seedlings with Isoproturon was inhibited. Chlorophyll content significantly decreased at the low concentration of Isoproturon (2 mg/kg), suggesting that chlorophyll was rather sensitive to Isoproturon exposure. The level of thiobarbituric acid reactive substances (TBARS), an indicator of cellular peroxidation, showed an increase, indicating oxidative damage to plants. The Isoproturon-induced oxidative stress resulted in a substantial change in activities of the majority of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Activities of the antiox...