Mineralization of 2,4-D and atrazine in the unsaturated zone of a sandy loam soil

Willems, Hans P. L.; Lewis, Kathleen; Dyson, Jeremy; Lewis, F. J.

doi:10.1016/0038-0717(96)00123-x

Cited by 55 publications

(39 citation statements)

References 32 publications

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“…The remaining 30 to 40% can be explained by the incorporation of 14 C from MCPA into biomass and into soil organic matter. Mineralization potentials of this magnitude have been reported elsewhere previously (41,61). Additionally, there is a tendency towards a slightly higher total mineralization in the subsoil experiment than in the topsoil, which can be explained by a larger degree of adsorption in the topsoil than in the subsoil.…”

Section: Discussionsupporting

confidence: 84%

Degradation of 4-Chloro-2-Methylphenoxyacetic Acid in Top- and Subsoil Is Quantitatively Linked to the Class III tfdA Gene

Bælum

Henriksen

Hansen

et al. 2006

Appl Environ Microbiol

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The tfdA gene is known to be involved in the first step of the degradation of the phenoxy acid herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) in several soil bacteria, but bacteria containing other tfdA-like genes have been isolated as well. A quantitative real-time PCR method was used to monitor the increase in the concentration of tfdA genes during degradation of MCPA in sandy topsoil and subsoil over a period of 115 days. Quantitative PCR revealed growth in the tfdA-containing bacterial community, from 500 genes g ؊1 soil to approximately 3 ؋ 10 4 genes g ؊1 soil and to 7 ؋ 10 5 genes g ؊1 soil for topsoil initially added to 2.3 mg MCPA kg ؊1 (dry weight) soil and 20 mg MCPA kg ؊1 (dry weight) soil, respectively. We analyzed the diversity of the tfdA gene during the degradation experiment. Analyses of melting curves of real-time PCR amplification products showed that a shift in the dominant tfdA population structure occurred during the degradation period. Further denaturing gradient gel electrophoresis and sequence analysis revealed that the tfdA genes responsible for the degradation of MCPA belonged to the class III tfdA genes, while the tfdA genes present in the soil before the occurrence of degradation belonged to the class I tfdA genes. The implications of these results is that the initial assessment of functional genes in soils does not necessarily reflect the organisms or genes that would carry out the degradation of the compounds in question.

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Section: Discussionsupporting

confidence: 84%

Degradation of 4-Chloro-2-Methylphenoxyacetic Acid in Top- and Subsoil Is Quantitatively Linked to the Class III tfdA Gene

Bælum

Henriksen

Hansen

et al. 2006

Appl Environ Microbiol

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“…Biodegradation rates vary with depth, as available nutrients and microbial biomass commonly decrease by more than 10-fold in the top 100 cm of soil (Willems et al 1996). Following to Jury et al (1987) the initial distribution of microbial biomass concentration with depth C MB0 (mg-C dm −3 ) was described by…”

Section: Solute Transport Modelmentioning

confidence: 99%

Modelling the Environmental Fate of the Herbicide Glyphosate in Soil Lysimeters

Klier

Grundmann

Gayler

et al. 2007

Water Air Soil Pollut: Focus

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In a risk assessment study the environmental fate of the herbicide glyphosate was studied with the specific background of the presence of genetically modified (GM) plants. Aim was to simulate the environmental behaviour of glyphosate in sandy field soil lysimeters after multiple herbicide applications and under the presence of GM soybean and to test and enhance model reliability in the simulation of the herbicide fate including biodegradation in the soil and herbicide translocation in GM plants. The modelling of the herbicide behaviour in the present study was based on the pesticide transport model LEACHP and the model PLANTX to simulate the pesticide uptake by plants. Both models were implemented in the modular modelling system EXPERT-N. Glyphosate transport measurements and the mathematical modelling results indicate that due to the high sorption of glyphosate to the soil matrix and the high microbial capacities for glyphosate degradation in the lysimeter soil, leaching risk can be considered to be low. We confirmed that the introduction of more adequate conceptual descriptions of microbial response to pesticide and nutrient additions can contribute to a reduction in the uncertainty of pesticide degradation modelling. Moreover, the consideration of uncertainty in sorption, dispersivity and degradation parameters revealed a considerable variability in model output. The observed accumulation of glyphosate in roots and nodules was reproduced by the simulation results. Under the restriction that the prevailing model assumptions are valid, the simulation results indicate that glyphosate may accumulate also in beans of trangenic soybean.

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“…The positive effect of carbon additions on atrazine mineralization is probably a result of cometabolic processes (Willems et al, 1996). Contrary findings on carbon-promoted degradation have been observed in agricultural soils having high atrazine concentrations (Silva et al, 2004;Xie et al, 2012).…”

Section: Discussionmentioning

confidence: 98%

“…Atrazine is moderately soluble in water, and it therefore leaches into the groundwater, where its half-life can increase up to nine times (Blume et al 2004). Pesticide degradation rates can be dramatically influenced by soil pH (Mueller et al, 2010), organic material (Cheyns et al 2012), temperature (Kookana et al 2010), and soil layer (Willems et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Bioremediation strategies for removal of residual atrazine in the boreal groundwater zone

Nousiainen

Björklöf

Sagarkar

et al. 2015

Appl Microbiol Biotechnol

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Strategies for bioremediation of atrazine, a pesticide commonly polluting groundwater in low concentrations, were studied in two boreal nonagricultural soils. Atrazine was not mineralized in soil without bioremediation treatments. In biostimulation treatment with molasses, up to 52% of atrazine was mineralized at 10 °C, even though the degradation gene copy numbers did not increase. Incubations with radioactively labeled atrazine followed by microautoradiographic analysis revealed that bioremediation strategies increased the relative proportion of active degraders from 0.3 up to 1.9% of the total bacterial count. These results indicate that atrazine degradation might not solely be facilitated by atzA/trzN-atzB genes. In combined biostimulation treatment using citrate or molasses and augmentation with Pseudomonas citronellolis ADP or Arthrobacter aurescens strain TC1, up to 76% of atrazine was mineralized at 30 °C, and the atrazine degradation gene numbers increased up to 10(7) copies g(-1) soil. Clone libraries from passive samplers in groundwater monitoring wells revealed the presence of phylogenetic groups formerly shown to include atrazine degraders, and the presence of atrazine degradation genes atzA and atzB. These results show that the mineralization of low concentrations of atrazine in the groundwater zone at low temperatures is possible by bioremediation treatments.

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Mineralization of 2,4-D and atrazine in the unsaturated zone of a sandy loam soil

Cited by 55 publications

References 32 publications

Degradation of 4-Chloro-2-Methylphenoxyacetic Acid in Top- and Subsoil Is Quantitatively Linked to the Class III tfdA Gene

Degradation of 4-Chloro-2-Methylphenoxyacetic Acid in Top- and Subsoil Is Quantitatively Linked to the Class III tfdA Gene

Modelling the Environmental Fate of the Herbicide Glyphosate in Soil Lysimeters

Bioremediation strategies for removal of residual atrazine in the boreal groundwater zone

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