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Trace element dynamics in the soil-plant system depends on multiple parameters, including chelating organic compounds from natural or synthetic organic matters. In this study, we evaluated the influence of one of the most common pesticides-glyphosate-on the mobility of trace elements considering contrasted soils (uncontaminated, anthropogenically contaminated, and naturally-enriched) in a greenhouse experiment. Four modalities have been tested: one control without any application, two with different glyphosate doses (1 and 3 times the authorised field dose), and one with compost addition to evaluate its potential ability to mitigate the impact of glyphosate on trace element mobility. Both, trace element and glyphosate concentrations were measured in the soil solutions and trace element contents were determined in plants at the end of the experiment. The results showed that, although glyphosate concentrations rapidly decreased in soil solutions, glyphosate application still influenced the transfer of trace elements to both soil solution (up to 12-times higher) and plant (up to 5.2-times higher). This influence was highly dependent on both the specific elements and the type of soils considered. For instance, in uncontaminated soils, glyphosate especially increased the mobilization of Mn, Co, Zn, Mo, and Pb to soil solution. This effect diminished of 2.5 times on average with increasing soil contamination. A similar trend was observed for the transfer of trace elements from soil to plant (i.e., on average 2.2-times lower in the most contaminated compared to the uncontaminated soil). However, in the naturally-enriched soil, opposing trends were noticed between soil solution and plant. The impact of compost addition on the transfer of trace elements to plants remains unclear: compost enhanced the transfer of trace elements to soil solution in uncontaminated and naturally-enriched soils likely due to trace element input through the compost, but decreased the transfer in anthropogenically-contaminated soils likely due to adsorption processes. Therefore, glyphosate could potentially increase the exposure of trace elements through food consumption and their transfer to the ecosystem, particularly in uncontaminated and weakly contaminated soils. In highly contaminated soils, compost could mitigate the glyphosate-induced enhancement of trace element mobility to soil solution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biodegradability testing in soil helps to identify safe synthetic organic chemicals but is still obscured by the formation of soil-bound 'non-extractable' residues (NERs). Present-day methodologies using radiocarbon or stable ( 13 C, 15 N) isotope labeling cannot easily differentiate soil-bound parent chemicals or transformation products (xenoNERs) from harmless soil-bound biomolecules of microbial degraders (bioNERs). Hypothesizing a minimal retention of hydrogen in biomolecules, we here apply stable hydrogen isotope - deuterium (D) - labeling to unravel the origin of NERs. Soil biodegradation tests with D- and 13 C-labeled 2,4-D, glyphosate and sulfamethoxazole reveal consistently lower proportions of applied D than 13 C in total NERs and in amino acids, a quantitative biomarker for bioNERs. Soil-bound D thus mostly represents xenoNERs and not bioNERs, enabling an efficient quantification of xenoNERs by just measuring the total bound D. D or tritium (T) labeling could thus improve the value of biodegradability testing results for diverse organic chemicals forming soil-bound residues., (© 2024. The Author(s).)

Large volumes of pesticides are applied every year to support agricultural production. The intensive use of pesticides affects soil quality and health, but soil surveys on pesticide residues are scarce, especially for northern Europe. We investigated the occurrence of 198 pesticide residues, including both banned and currently used substances in 148 field sites in Finland. Results highlight that pesticide residues are common in the agricultural soils of Finland. A least one residue was found in 82% of the soils, and of those 32% contained five or more residues. Maximum total residue concentration among the conventionally farmed soils was 3043 μg/kg, of which AMPA and glyphosate contributed the most. Pesticide residues were also found from organically farmed soils, although at 75-90% lower concentrations than in the conventionally farmed fields. Thus, despite the application rates of pesticides in Finland being generally much lower than in most parts of central and southern Europe, the total residue concentrations in the soils occurred at similar or at higher levels. We also established that AMPA and glyphosate residues in soil are significantly higher in fields with cereal dominated rotations than in grass dominated or cereal-grass rotations. However, risk analyses for individual substances indicated low ecological risk for most of the fields. Furthermore, the total ecological risk associated with the mixtures of residues was mostly low except for 21% of cereal dominated fields with medium risk. The results showed that the presence of mixtures of pesticide residues in soils is a rule rather than an exception also in boreal soils. In highly chemicalized modern agriculture, the follow-up of the residues of currently used pesticides in national and international soil monitoring programs is imperative to maintain soil quality and support sustainable environment policies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In this paper, several experiments were carried out to study the environmental behavior and influencing factors of glyphosate (PMG) in peach orchard ecosystem. The results of field experiments showed that PMG and its metabolite aminomethylphosphonic acid (AMPA) were detected in peach tree leaves and peach tree fruits, although PMG was only sprayed on the soil. The residues of PMG and AMPA in peach tree leaves were ~0.1 mg/kg and ~0.5 mg/kg and in peach tree fruits were ~0.01 mg/kg and 0.07-0.11 mg/kg, respectively. By conducting a series of laboratory simulation experiments, the environmental factors affecting the degradation of PMG were screened and evaluated. The results showed that PMG metabolized much faster in loess soil than red soil and black soil (with the DT 50 of 11.6 days, 62.4 days, and 34.1 days, respectively). By analyzing the basic properties of the soil, we investigated the effects of pH, moisture content, organic matter (exogenous biochar) and ambient temperature using orthogonal experiments, and the results were further confirmed by microbial experiment. The results showed that alkaline conditions (pH = 7.8/9), high water content (25%) and microorganisms could promote the degradation of PMG. Sterile soil environment had a negative impact on the metabolic behavior of PMG to AMPA., (Copyright © 2020. Published by Elsevier Inc.)

Glyphosate is a broad-spectrum, non-selective, post-emergence herbicide that controls weeds by inhibiting their ability to synthesize amino acids. It is characterized by high persistence and adsorption to soil, with its dissipation to be highly correlated to the climatic conditions. After its degradation in soil, aminomethylphosphonic acid (AMPA) is the sole and major metabolite produced, characterized also by high persistence and adsorption. Both substances have the potential to remain in soil rather than move to other environmental compartments. Considering the recent intense debate during the EU renewal of glyphosate along with its wide use, it is apparent that both glyphosate and AMPA require further attention and information on their occurrence and distribution in EU soils. The present study does constitute the first extended soil monitoring survey of glyphosate and AMPA with samples derived during the years 2013-2015, from the highest extent of the Greek territory. Specific attention was given to areas of high agricultural production as well as to urban areas, since glyphosate-containing products are also registered for non-professional uses. The positive samples represented the 36.7% for glyphosate and 44.9% for AMPA, while the detected residues fluctuated from 0.026 to 40.6 μg g -1 and from 0.01 to 2.5 μg g -1 for glyphosate and AMPA, respectively. Our findings can constitute a basis for the determination of the background concentration levels of glyphosate and its metabolite in the Greek territory. As such, apart from being the first study for glyphosate monitoring in Greece, the most significant highlights recognized in the present work are the following:The high levels of glyphosate and AMPA residues in urban areas that indicate possible misuse of pesticidesThe generally low detection in the main agricultural basins and particularly near water recipientsThe fact that a potential for misuse of herbicides cannot be excluded even in the case of agricultural areas (considering that the maximum detection was in an olive grove and exceeded the model-predicted concentrations by 13 times).

Although the use of agrochemicals allowed increasing the crops productivity, in many cases led to soil deterioration. In this study, eight composite samples from different soils of two locations (San Martín and Anta) in Salta, Argentina, were collected and analyzed. All the samples were from loamy Entisols (0-20 cm depth) under reduced tillage without and with direct spray application of glyphosate. Twenty six variables were determined (physical, chemical, and biological soil quality indicators). From them, those of higher specificity and sensitivity to changes following glyphosate application were identified by a stepwise reduction of variables aided by statistical analysis. Samples were grouped regarding location and application of glyphosate, to identify differential effects upon variables, and glyphosate sensitive variables were selected by discarding those influenced by other factors. Thence, they were used to compose a first approximation to a combined soil quality indicator (CSQI) to assess the effect of glyphosate use in agriculture upon the soil. Overall, the set of physical variables showed the same discriminating structure as the biological set. Finally, two biological, two chemical, and two physical indicators resulted as the most specific to quality variations by the application of the herbicide, being the most sensitive the microbial biomass carbon and the (Aminomethyl)phosphonic acid concentration in soil. When these two were considered into a CSQI, it was possible to discriminate samples with the application of glyphosate (lower quality) from those without application (higher quality). To the best of our knowledge, this is the first attempt to propose a CSQI that could play an important role to prevent degradation in soils subjected to glyphosate application, as it could aid in the early detection of soil quality loss. This would provide to land managers a decision tool to let the land rest from glyphosate application, to ensure sustainable practices in agriculture., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Although glyphosate is widely used in agriculture, information on its residue level in soils remains scarce partly because of the difficulty in its analysis. Objective: Develop and validate a method to directly analyze glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in soil. Method: Soils were extracted with 0.6 M KOH solution, and coextracted interferences were removed using a mixed-mode Bond Elut Plexa PAX ® . The extracts were analyzed by LC-tandem MS fitted with a Hypercarb column and isotope-labeled ( 13 C, 15 N) glyphosate and AMPA were used as internal standards. Results: LOQs were 0.05 mg/kg for both glyphosate and AMPA in soils. Correlation coefficients were ≥0.99, residuals were below 20%, and calibrations were linear in the range 0.02-1.0 μg/mL. The method was validated on five contrasting soils (Vertosol, Calcarosol, Chromosol, Sodosol, and Tenosol) commonly used for grain production in Australia. The recoveries for glyphosate and AMPA in the soils were 96-121 and 91-118%, respectively, with RSD in the range of 3-16%. Conclusions: This paper presents using the validated method in analysis glyphosate and AMPA in soils collected from crop production paddocks in Australia. The survey data showed that glyphosate and AMPA were detected in all collected soils, with concentrations ranging between 0.05 and 1.2 mg/kg. Highlights: The study demonstrates that the mixed-mode solid-phase extraction is effective in removing interferences and validates the use of Hypercarb as an alternative stationary phase for glyphosate and AMPA analysis from soils.

Glyphosate (GLP) is one of the most widely-used herbicides globally and its toxicity to humans and the environment is controversial. GLP is biodegradable, but little is known about the importance of site exposure history and other environmental variables on the rate and pathway of biodegradation. Here, GLP was added to microcosms of soils and sediments with different exposure histories and these were incubated with amendments of glucose, ammonium, and phosphate. GLP concentrations were measured with a newly-developed HPLC method capable of tolerating high concentrations of ammonium and amino acids. GLP biodegradation occurred after a lag-time proportional to the level of GLP pre-exposure in anthropogenically-impacted samples (soils and sediments), while no degradation occurred in samples from a pristine sediment after 180 days of incubation. Exposure history did not influence the rate of GLP degradation, after the lag-time was elapsed. Addition of C, N, and P triggered GLP degradation in pristine sediment and shortened the lag-time before degradation in other samples. In all microcosms, GLP was metabolised into aminomethylphosphonic acid (AMPA), which was highly persistent, and thus appears to be a more problematic pollutant than GLP. Bacterial communities changed along the gradients of anthropogenic impacts, but in some cases, taxonomically very-similar communities showed dramatically different activities with GLP. Our findings reveal important interactions between agriculturally-relevant nutrients and herbicides., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The accumulation of plastic debris and herbicide residues has become a huge challenge and poses many potential risks to environmental health and soil quality. In the present study, we investigated the transport of glyphosate and its main metabolite, aminomethylphosphonic acid (AMPA) via earthworms in the presence of different concentrations of light density polyethylene microplastics in the litter layer during a 14-day mesocosm experiment. The results showed earthworm gallery weight was negatively affected by the combination of glyphosate and microplastics. Glyphosate and AMPA concentrated in the first centimetre of the top soil layer and the downward transport of glyphosate and AMPA was only detected in the earthworm burrows, ranging from 0.04 to 4.25 μg g -1 for glyphosate and from 0.01 (less than limit of detection) to 0.76 μg g -1 for AMPA. The transport rate of glyphosate (including AMPA) from the litter layer into earthworm burrows ranged from 6.6 ± 4.6% to 18.3 ± 2.4%, depending on synergetic effects of microplastics and glyphosate application. The findings imply that earthworm activities strongly influence pollutant movement into the soil, which potentially affects soil ecosystems. Further studies focused on the fate of pollutants in the microenvironment of earthworm burrows are needed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Glyphosate represents one quarter of global herbicide sales, with growing interest in both its fate in soils and potential to cause non-target phytotoxicity to plants. However, assessing glyphosate bioavailability to plants from soil residues remains challenging. Here we demonstrate that the diffusive gradient in thin-films technique (DGT) can effectively measure available glyphosate across boundary conditions typical of the soil environment: pH 4-9, P concentrations of 20-300 μg P L -1 and NaHCO 3 concentrations of 10-1800 mg L -1 . In this study, four soils with different glyphosate sorption properties were dosed with up to 16 mg kg -1 of glyphosate and phytotoxicity to wheat and lupin was measured against the DGT-glyphosate concentrations. An improved dose response curve was obtained for root elongation of wheat and lupin across soil types when DGT-glyphosate was used instead of alkaline-extractable (i.e., total extractable) glyphosate. Total extractable glyphosate concentrations of 2.6 and 5.0 mg glyphosate kg -1 in the sandy Tenosol, equivalent to 2.9 and 6.5 μg L -1 DGT-extractable glyphosate, reduced the root length of lupins (but not wheat) by 32-36% compared with the untreated control. DGT is therefore a promising method for assessing phytotoxic levels of glyphosate across different soils., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study investigates the dynamics of glyphosate and AMPA in the soil surface layer of two fields growing glyphosate-resistant crops in the loess Pampas of Córdoba Province, Argentina. Glyphosate decay and AMPA formation/decay were studied after a single application, using decay kinetic models. Furthermore, glyphosate and AMPA concentrations were investigated in runoff to evaluate their off-site risk. During a 2.5-month study, cultivations of glyphosate-resistant soybean and maize received an application of 1.0 and 0.81 kg a.e. ha -1 , respectively, of Roundup UltraMax © . Topsoil samples (0-1, 1-2 cm) were collected weekly (including before application) and analysed for glyphosate, AMPA and soil moisture (SM) contents. Runoff was collected from runoff plots (3 m 2 ) and weirs after 2 erosive rainfall events, and analysed for glyphosate and AMPA contents (water, eroded-sediment). Under both cultivations, background residues in soil before application were 0.27-0.42 mg kg -1 for glyphosate and 1.3-1.7 mg kg -1 for AMPA. In the soybean area, the single-first-order (SFO) model performed best for glyphosate decay. In the maize area, the bi-phasic Hockey-Stick (HS) model performed best for glyphosate decay, due to an abrupt change in SM regimes after high rainfall. Glyphosate half-life and DT 90 were 6.0 and 19.8 days, respectively, in the soybean area, and 11.1 and 15.4 days, respectively, in the maize area. In the soybean area, 24% of the glyphosate was degraded to AMPA. In the maize area, it was only 5%. AMPA half-life and DT 90 were 54.7 and 182 days, respectively, in the soybean area, and 71.0 and 236 days, respectively, in the maize area. Glyphosate and AMPA contents were 1.1-17.5 times higher in water-eroded sediment than in soil. We conclude that AMPA persists and may accumulate in soil, whereas both glyphosate and AMPA are prone to off-site transport with water erosion, representing a contamination risk for surface waters and adjacent fields., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Glyphosate (GLP) currently is one of the most widely used herbicides worldwide. The persistence of GLP and its major metabolite, aminomethylphosphonic acid (AMPA) in the environment has been described by other authors. This study was aimed at comparing the GLP and AMPA behavior in sandy and loamy sand soils after spiking with enhanced (445 µg g -1 ) concentrations of GLP in herbicide KLINIK ® (Nufarm, Austria) and bioaugmentation followed by 40 days weathering and a consistent three-stage leaching in a laboratory column experiment. Soil samples were obtained from mineral topsoil (0-10 cm) within former agricultural lands where soil parent material was formed by glacigenic deposits. The total amount of GLP and AMPA collected during three leaching stages was significantly ( p <.05) higher from columns with sandy soil, compared to loamy sand soil. Bioaugmentation resulted in considerably lower concentrations of AMPA in leachates, especially in the sets with sandy soil ( p =.01). Leachates were tested using FTIR spectroscopy and Daphnia magna . Statistical analysis of the changes in N tot , C tot , K + , Mg 2+ , Al 3+ , Ca 2+ , Mn 2+ and Fe 3+ concentrations in soils after the leaching experiment revealed that the loamy sand soil was likely to be more sensitive to the addition of GLP and bioaugmentation than sandy soil.

A sensitive linker-assisted enzyme-linked immunosorbent assay (L'ELISA) was developed for the analysis of glyphosate in Egyptian soil samples. Polyclonal glyphosate antibodies were produced from rabbits immunized with glyphosate protein conjugate. The conjugate was prepared by activating the carboxylic groups of proteins; thyroglobulin or bovine serum albumin with 1-ethyl-3- (3-diaminopropyl) carbodiimide hydrochloride and N-hydroxysulfosuccinimide followed by directly coupled to the amino group of glyphosate. The L'ELISA used succinic anhydride to derivatize glyphosate, which mimics the epitopic attachment of glyphosate to thyroglobulin. L'ELISA recognized the derivatized glyphosate with a limit of detection (LOD) of 0.8 ng g -1 and sensitivity (IC 50 value) of 0.018 μg g -1 . The recovery values of the spiked soil samples with different concentrations of glyphosate were in the range of 87.4-97.2%. Good correlation was achieved between L'ELISA and conventional high-pressure liquid chromatography (HPLC) with fluorescence detection. This study demonstrated the utility and convenience of the sensitive, simple, practical and cost-effective L'ELISA method for glyphosate analysis in soil samples. Also, it is ideal for rapid screening of a large number of environmental samples., (Copyright © 2018 Elsevier Inc. All rights reserved.)

This study evaluates the glyphosate dissipation under field conditions in three types of soil, and aims to determine the importance of the following factors in the environmental persistence of herbicide: i) soil bacterial communities, ii) soil physicochemical properties, iii) previous exposure to the herbicide. A soil without previous record of GP application (P0) and two agricultural soils, with 5 and >10years of GP exposure (A5 and A10) were subjected to the application of glyphosate at doses of 3mg·kg -1 . The concentration of GP and AMPA was determined over time and the dynamics of soil bacterial communities was evaluated using 16S ARN ribosomal gene amplicon-sequencing. The GP exposure history affected the rate but not the extent of GP biodegradation. The herbicide was degraded rapidly, but P0 soil showed a dissipation rate significantly lower than soils with agricultural history. In P0 soil, a significant increase in the relative abundance of Bacteroidetes was observed in response to herbicide application. More generally, all soils displayed shifts in bacterial community structure, which nevertheless could not be clearly associated to glyphosate dissipation, suggesting the presence of redundant bacteria populations of potential degraders. Yet the application of the herbicide prompted a partial disruption of the bacterial association network of unexposed soil. On the other hand, higher values of linear (Kd) and nonlinear (Kf) sorption coefficient in P0 point to the relevance of cation exchange capacity (CEC), clay and organic matter to the capacity of soil to adsorb the herbicide, suggesting that bioavailability was a key factor for the persistence of GP and AMPA. These results contribute to understand the relationship between bacterial taxa exposed to the herbicide, and the importance of soil properties as predictors of the possible rate of degradation and persistence of glyphosate in soil., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The most worldwide used herbicide is glyphosate, phosphonomethylglycine (PMG). Consequently, a significant amount of PMG, its metabolites (sarcosine, SAR, and aminomethylphosphonic acid, AMPA) and the degradation product, methylphosphonic acid (MPA), reaches the soil, which acts as final sink. Because clays are one of the most reactive components of soils, expansive clays such as montmorillonite (Mt) are used to retain agriculture contaminants with some success. In this work, as a preliminary step for the evaluation of the risk that PMG, SAR, AMPA, and MPA occurrence could have on the environment, their adsorption on Mt surface was performed. The adsorption process was analyzed at constant adsorbate concentrations and two pH values to take into account the different protonation states of the amino group. DTA, XRD, zeta potential measurements, and XPS were used to identify the interactions or association mechanisms with the clay surface, the entry of adsorbates into the Mt interlayer, and electric charge changes on the Mt surface, and evaluate the acid-base surface complex constants, respectively. The interlayer thickness in acid media indicated that adsorbates are able to enter the interlayer in planar form. Besides, for the Mt-PMG sample, some PMG molecules could be also inserted as a bilayer or with a tilt angle of 52.4° in the interlayer. However, in alkaline media, the interlayer thickness indicated that the adsorbate arrangement differed from that of acidic media where PMG and MPA could have more than one orientation. The surface complex deprotonation constants were determined for the =NH +2  ⇆ =NH+H + process, being 3.0, 5.0, and 7.3 for PMG, AMPA, and SAR, respectively.

We measured the occurrence and seasonal variations of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in different environmental compartments within the limits of an agricultural basin. This topic is of high relevance since glyphosate is the most applied pesticide in agricultural systems worldwide. We were able to quantify the seasonal variations of glyphosate that result mainly from endo-drift inputs, that is, from direct spraying either onto genetically modified (GM) crops (i.e., soybean and maize) or onto weeds in no-till practices. We found that both glyphosate and AMPA accumulate in soil, but the metabolite accumulates to a greater extent due to its higher persistence. Knowing that glyphosate and AMPA were present in soils (> 93% of detection for both compounds), we aimed to study the dispersion to other environmental compartments (surface water, stream sediments, and groundwater), in order to establish the degree of non-point source pollution. Also, we assessed the relationship between the water-table depth and glyphosate and AMPA levels in groundwater. All of the studied compartments had variable levels of glyphosate and AMPA. The highest frequency of detections was found in the stream sediments samples (glyphosate 95%, AMPA 100%), followed by surface water (glyphosate 28%, AMPA 50%) and then groundwater (glyphosate 24%, AMPA 33%). Despite glyphosate being considered a molecule with low vertical mobility in soils, we found that its detection in groundwater was strongly associated with the month where glyphosate concentration in soil was the highest. However, we did not find a direct relation between groundwater table depth and glyphosate or AMPA detections. This is the first simultaneous study of glyphosate and AMPA seasonal variations in soil, groundwater, surface water, and sediments within a rural basin.

This study investigates the influence of small-scale sediment transport on glyphosate and AMPA redistribution on the soil surface and on their off-site transport during water erosion events. Both a smooth surface (T1) and a surface with "seeding lines on the contour" (T2) were tested in a rainfall simulation experiment using soil flumes (1 × 0.5 m) with a 5% slope. A dose of 178 mg m -2 of a glyphosate-based formulation (CLINIC ® ) was applied on the upper 0.2 m of the flumes. Four 15-min rainfall events (RE) with 30-min interval in between and a total rainfall intensity of 30 mm h -1 were applied. Runoff samples were collected after each RE in a collector at the flume outlet. At the end of the four REs, soil and sediment samples were collected in the application area and in four 20 cm-segments downslope of the application area. Samples were collected according to the following visually distinguished soil surface groups: light sedimentation (LS), dark sedimentation (DS), background and aggregates. Results showed that runoff, suspended sediment and associated glyphosate and AMPA off-site transport were significantly lower in T2 than in T1. Glyphosate and AMPA off-site deposition was higher for T2 than for T1, and their contents on the soil surface decreased with increasing distance from the application area for all soil surface groups and in both treatments. The LS and DS groups presented the highest glyphosate and AMPA contents, but the background group contributed the most to the downslope off-site deposition. Glyphosate and AMPA off-target particle-bound transport was 9.4% (T1) and 17.8% (T2) of the applied amount, while water-dissolved transport was 2.8% (T1) and 0.5% (T2). Particle size and organic matter influenced the mobility of glyphosate and AMPA to off-target areas. These results indicate that the pollution risk of terrestrial and aquatic environments through runoff and deposition can be considerable., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Glyphosate (GLP) herbicide leaching into soil can undergo abiotic degradation and two enzymatic oxidative or hydrolytic reactions in both aerobic and anaerobic conditions; biotic oxidation produces aminomethylphosphonic acid (AMPA). Both GLP and AMPA are phytotoxic. A comprehensive GLP degradation reaction network was developed from the literature to account for the above pathways, and fifteen experimental data sets were used to determine the corresponding Michaelis-Menten-Monod (MMM) kinetic parameters. Various sensitivity analyses were designed to assess GLP and AMPA degradation potential against O 2 (aq) and carbon (C) availability, pH, and birnessite mineral content, and showed that bacteria oxidized or hydrolyzed up to 98% of GLP and only 9% of AMPA. Lack of a C source limited the GLP cometabolic hydrolytic pathways, which produces non-toxic byproducts and promotes AMPA biodegradation. Low bacterial activity in O 2 (aq)-limited conditions or non-neutral pH resulted in GLP accumulation. Birnessite mineral catalyzed fast GLP and AMPA chemodegradation reaching alone efficiencies of 79% and 88%, respectively, regardless of the other variables and produced non-toxic byproducts. Overall, O 2 (aq) and birnessite availability played the major roles in determining the partitioning of GLP and its byproducts mass fluxes across the reaction network, while birnessite, C availability, and pH affected GLP and AMPA biodegradation effectiveness., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Glyphosate, which is commercially available as Roundup®, was the widely used herbicide in Sri Lanka until 2015 and is suspected to be one of the causal factors for Chronic Kidney Disease of unknown etiology (CKDu). This research, therefore, aims at studying the presence of glyphosate and Aminomethylphosphonic acid (AMPA) in different environmental matrices in CKDu prevalent areas. Topsoil samples from agricultural fields, water samples from nearby shallow wells and lakes, and sediment samples from lakes were collected and analyzed for glyphosate and AMPA using the LC/MS. Glyphosate (270-690 µg/kg) and AMPA (2-8 µg/kg) were detected in all soil samples. Amorphous iron oxides and organic matter content of topsoil showed a strong and a moderate positive linear relationship with glyphosate. The glyphosate and inorganic phosphate levels in topsoil had a strong negative significant linear relationship. Presence of high valence cations such as Fe 3+ and Al 3+ in topsoil resulted in the formation of glyphosate-metal complexes, thus strong retention of glyphosate in soil. Lower levels of AMPA than the corresponding glyphosate levels in topsoil could be attributed to factors such as the strong adsorption capacity of glyphosate to soil and higher LOQ in the quantification of AMPA. The glyphosate levels of lakes were between 28 to 45 µg/L; no AMPA was detected. While trace levels of glyphosate (1-4 µg/L) were detected in all groundwater samples, AMPA (2-11µg/L) was detected only in four out of nine samples. Glyphosate was detected in all sediment samples (85-1000 µg/kg), and a strong linear relationship with the organic matter content was observed. AMPA was detected (1-15 µg/kg) in seven out of nine sediment samples. It could be inferred that the impact on CKDu by the levels of glyphosate and AMPA detected in the study area is marginal when compared with the MCL of the USEPA (700 µg/L).

In the Pampas, public concern has strongly risen because of the intensive use of glyphosate for weed control and fallow associated with biotech crops. The present study was aimed to evaluate the occurrence and concentration of the herbicide and its main metabolite (AMPA) in soil and other environmental compartments of the mentioned agroecosystem, including groundwater, in relation to real-world agricultural management practices in the region. Occurrence was almost ubiquitous in solid matrices (83-100%) with maximum concentrations among the higher reported in the world (soil: 8105 and 38939; sediment: 3294 and 7219; suspended particulate matter (SPM): 584 and 475 μg/kg of glyphosate and AMPA). Lower detection frequency was observed in surface water (27-55%) with maximum concentrations in whole water of 1.80 and 1.90 μg/L of glyphosate and AMPA, indicating that SPM analysis would be more sensitive for detection in the aquatic ecosystem. No detectable concentrations of glyphosate or AMPA were observed in groundwater. Glyphosate soil concentrations were better correlated with the total cumulative dose and total number of applications than the last spraying event dose, and an increment of 1 mg glyphosate/kg soil every 5 spraying events was estimated. Findings allow to infer that, under current practices, application rates are higher than dissipation rates. Hence, glyphosate and AMPA should be considered "pseudo-persistent" pollutants and a revisions of management procedures, monitoring programs, and ecological risk for soil and sediments should be also recommended., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The uptake, translocation, metabolism, and distribution behavior of glyphosate in nontarget tea plant were investigated. The negative effects appeared to grown tea saplings when the nutrient solution contained glyphosate above 200 mg L -1 . Glyphosate was highest in the roots of the tea plant, where it was also metabolized to aminomethyl phosphonic acid (AMPA). The glyphosate and AMPA in the roots were transported through the xylem or phloem to the stems and leaves. The amount of AMPA in the entire tea plant was less than 6.0% of the amount of glyphosate. The glyphosate level in fresh tea shoots was less than that in mature leaves at each day. These results indicated that free glyphosate in the soil can be continuously absorbed by, metabolized in, and transported from the roots of the tea tree into edible leaves, and therefore, free glyphosate residues in the soil should be controlled to produce teas free of glyphosate.

Pesticide sorption to ditch-bed materials can efficiently decrease pesticide concentrations in the flowing water. Pesticide sorption depends on flood characteristics and the nature and abundance of ditch-bed materials, such as soils, living and decaying vegetation and ash. However, the affinities of pesticides for various ditch-bed materials have rarely been investigated, and variations in the global sorption capacity of ditch beds resulting from their heterogeneous compositions and variable flood characteristics have not been determined. Thus, we studied the variability of sorption capacities of ditch-bed materials for glyphosate and diuron in three catchments in France and propose a method for calculating global sorption processes in heterogeneous ditch beds. The methodology consists in estimating a global sorption coefficient for the composite ditch-bed materials (Kd ditch ) and an indicator of the amount of pesticide potentially retained by sorption during a flood event (SPRI). Furthermore, we computed the Kd ditch and SPRI of glyphosate and diuron for 8 ditches subjected to 3h flood events with water levels varying from 0.5 to 15cm. Our results show that increasing the water level from 0.5 to 15cm resulted in a 90% decrease in the sorption capacities of the ditch beds for both pesticides. At a medium water depth of 5cm, SPRI varied from 25 to 51% and from 7 to 35% among the ditches for glyphosate and diuron, respectively. The variabilities of the glyphosate and diuron sorption capacities among the ditches were mainly driven by the nature and abundance of soil and ash. As the management of farm ditches, performed to maintain their hydraulic performance, modifies the abundances of various ditch-bed materials, it constitutes a potential lever of action for water quality improvement. Thus, Kd ditch and SPRI could serve as rapid and cost-effective tools for optimizing ditch network management strategies to improve water quality in cropped catchments., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The dissipation kinetics of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) were studied in loess soil, under biotic and abiotic conditions, as affected by temperature, soil moisture (SM) and light/darkness. Nonsterile and sterile soil samples were spiked with 16mgkg -1 of glyphosate, subjected to three SM contents (20% WHC, 60% WHC, saturation), and incubated for 30days at 5°C and 30°C, under dark and light regimes. Glyphosate and AMPA dissipation kinetics were fit to single-first-order (SFO) or first-order-multicompartment (FOMC) models, per treatment combination. AMPA kinetic model included both the formation and decline phases. Glyphosate dissipation kinetics followed SFO at 5°C, but FOMC at 30°C. AMPA followed SFO dissipation kinetics for all treatments. Glyphosate and AMPA dissipation occurred mostly by microbial activity. Abiotic processes played a negligible role for both compounds. Under biotic conditions, glyphosate dissipation and AMPA formation/dissipation were primarily affected by temperature, but also by SM. Light regimes didn't play a significant role. Glyphosate DT50 varied between 1.5 and 53.5days, while its DT90 varied between 8.0 and 280days, depending on the treatment. AMPA persisted longer in soil than glyphosate, with its DT50 at 30°C ranging between 26.4 and 44.5days, and its DT90 between 87.8 and 148days. The shortest DT50/DT90 values for both compounds occurred at 30°C and under optimal/saturated moisture conditions, while the largest occurred at 5°C and reaching drought stress conditions. Based on these results, we conclude that glyphosate and AMPA dissipate rapidly under warm and rainy climate conditions. However, repeated glyphosate applications in fallows or winter crops in countries where cold and dry winters normally occur could lead to on-site soil pollution, with consequent potential risks to the environment and human health. To our knowledge, this study is the first evaluating the combined effect of temperature, soil moisture and light/dark conditions on AMPA formation/dissipation kinetics and behaviour., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Worldwide, glyphosate is the most widely used herbicide in controlling the growth of annual and perennial weeds. An increasing number of studies have highlighted the environmental risk resulting from the use of this molecule in aquatic and terrestrial ecosystems. The objective of the study was to determine the transport of glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), through runoff and transported sediment from a vineyard under two different soil management systems: harrowed inter-row (HR) and permanent grass covered inter-row (GR). The study was performed over a period of 4 yr. Glyphosate and AMPA concentrations were found to be higher in runoff and in transported sediment from HR compared with GR, regardless of the amount of runoff and transported sediment. The mean annual percentages of glyphosate loss, via runoff and transported sediment, were about 1.37 and 0.73% for HR and GR, respectively. Aminomethylphosphonic acid represented approximately 30.9 and 40.0% of the total glyphosate losses in GR and HR, respectively. Moreover, results suggested that rains occurring within 4 wk after treatment could cause the transport of glyphosate and AMPA in high concentrations. Soil analyses indicated that glyphosate content was below detection within 1 yr, whereas AMPA remained in the soil profiles along the vine row and in the inter-row. Results indicated that GR can reduce soil and herbicide loss by runoff in vineyard cropping system., (Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.)

Adsorption of the herbicide glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) was investigated on 17 different agricultural soils. Batch equilibration adsorption data are shown by Freundlich adsorption isotherms. Glyphosate adsorption is clearly affected by equilibration concentrations, but the nonlinear AMPA adsorption isotherms indicate saturation of the adsorption sites with increasing equilibrium concentrations. pHCaCl2 (i.e. experimental pH) is the major parameter governing glyphosate and AMPA adsorption in soils. However, considering pHCaCl2 values, available phosphate amount, and amorphous iron and aluminium oxide contents by using a nonlinear multiple regression equation, obtains the most accurate and powerful pedotransfer rule for predicting the adsorption constants for these two molecules. As amorphous iron and aluminium oxide contents in soil are not systematically determined, we also propose a pedotransfer rule with two variables-pHCaCl2 values and available phosphate amount-that remains acceptable for both molecules. Moreover, the use of the commonly measured pHwater or pHKCl values gives less accurate results compared to pHCaCl2 measurements. To our knowledge, this study is the first AMPA adsorption characterization for a significant number of temperate climate soils.

The increasing use of cover crops (CC) may lead to an increase in glyphosate application for their destruction. Sorption and degradation of (14)C-glyphosate on and within 4 decaying CC-amended soils were compared to its fate in a bare soil. (14)C-Glyphosate and its metabolites distribution between mineralized, water-soluble, NH4OH-soluble and non-extractable fractions was determined at 5 dates during a 20 °C/84-d period. The presence of CC extends (14)C-glyphosate degradation half-life from 7 to 28 days depending on the CC. (14)C-Glyphosate dissipation occurred mainly through mineralization in soils and through mineralization and bound residue formation in decaying CC. Differences in sorption and degradation levels were attributed to differences in composition and availability to microorganisms. CC- and soil-specific dissipation patterns were established with the help of explicit relationships between extractability and microbial activity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

There is a need for simple, fast, efficient and sensitive methods of analysis for glyphosate and its degradate aminomethylphosphonic acid (AMPA) in diverse matrices such as water, plant materials and soil to facilitate environmental research needed to address the continuing concerns related to increasing glyphosate use. A variety of water-based solutions have been used to extract the chemicals from different matrices. Many methods require extensive sample preparation, including derivatization and clean-up, prior to analysis by a variety of detection techniques. This review summarizes methods used during the past 15 years for analysis of glyphosate and AMPA in water, plant materials and soil. The simplest methods use aqueous extraction of glyphosate and AMPA from plant materials and soil, no derivatization, solid-phase extraction (SPE) columns for clean-up, guard columns for separation and confirmation of the analytes by mass spectrometry and quantitation using isotope-labeled internal standards. They have levels of detection (LODs) below the regulatory limits in North America. These methods are discussed in more detail in the review., (© 2015 Society of Chemical Industry.)

Repeated applications of glyphosate may contaminate the soil and water and threaten their quality both within the environmental system and beyond it through water erosion related processes and leaching. In this study, we focused on the transport of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) related to soil erosion at two slope gradients (10 and 20°), two rates of pesticide with a formulation of glyphosate (Roundup®) application (360 and 720 mg m(-2)), and a rain intensity of 1.0 mm min(-1) for 1 h on bare soil in hydraulic flumes. Runoff and erosion rate were significantly different within slope gradients (p<0.05) while suspended load concentration was relatively constant after 15 min of rainfall. The glyphosate and AMPA concentration in the runoff and suspended load gradually decreased. Significant power and exponent function relationship were observed between rainfall duration and the concentration of glyphosate and AMPA (p<0.01) in runoff and suspended load, respectively. Meanwhile, glyphosate and AMPA content in the eroded material depended more on the initial rate of application than on the slope gradients. The transport rate of glyphosate by runoff and suspended load was approximately 14% of the applied amount, and the chemicals were mainly transported in the suspended load. The glyphosate and AMPA content in the flume soil at the end of the experiment decreased significantly with depth (p<0.05), and approximately 72, 2, and 3% of the applied glyphosate (including AMPA) remained in the 0-2, 2-5, and 5-10 cm soil layers, respectively. The risk of contamination in deep soil and the groundwater was thus low, but 5% of the initial application did reach the 2-10 cm soil layer. The risk of contamination of surface water through runoff and sedimentation, however, can be considerable, especially in regions where rain-induced soil erosion is common., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The acute and subacute toxicities of cadmium (Cd) to earthworm Eisenia fetida in the presence and absence of glyphosate were studied. Although Cd is highly toxic to E. fetida, the presence of glyphosate markedly reduced the acute toxicity of Cd to earthworm; both the mortality rate of the earthworms and the accumulation of Cd decreased with the increase of the glyphosate/Cd molar ratio. The subcellular distribution of Cd in E. fetida tissues showed that internal Cd was dominant in the intact cells fraction and the heat-stable proteins fraction. The presence of glyphosate reduced the concentration of Cd in all fractions, especially the intact cells. During a longer period of exposure, the weight loss of earthworm and the total Cd absorption was alleviated by glyphosate. Thus, the herbicide glyphosate can reduce the toxicity and bioavailability of Cd in the soil ecosystems at both short- and long-term exposures., (© 2014 SETAC.)

Adult mortality, biomass, fecundity and viability of cocoons were studied in Eisenia fetida and Octolasion tyrtaeum, in response to glyphosate exposure in soil. Exposure tests were carried out following USEPA procedure, with five concentrations of glyphosate in soil and a control. O. tyrtaeum was more sensitive to the highest concentration of glyphosate (50,000 mg kg(-1)), with 100 % mortality by day 7 of exposure, compared with 71 % for E. fetida. Although biomass of O. tyrtaeum was significantly different between the control and 5,000 mg kg(-1) dose at day 14, E. fetida was not affected at that concentration, and only showed a significant weight loss after 7 days of exposure to 50,000 mg kg(-1). Adverse effects upon adult fecundity and cocoon viability were observed at glyphosate concentrations of 5,000 mg kg(-1) and above. Adverse effects were observed at concentrations that greatly exceeded the recommended field application rates of glyphosate.

Argentinian agricultural production is fundamentally based on a technological package that combines no-till and glyphosate in the cultivation of transgenic crops. Transgenic crops (soybean, maize and cotton) occupy 23 million hectares. This means that glyphosate is the most employed herbicide in the country, where 180-200 million liters are applied every year. The aim of this work is to study the environmental fate of glyphosate and its major degradation product, aminomethylphosphonic acid (AMPA), in surface water and soil of agricultural basins. Sixteen agricultural sites and forty-four streams in the agricultural basins were sampled three times during 2012. The samples were analyzed by UPLC-MS/MS ESI(+/-). In cultivated soils, glyphosate was detected in concentrations between 35 and 1502 μg kg(-1), while AMPA concentration ranged from 299 to 2256 μg kg(-1). In the surface water studied, the presence of glyphosate and AMPA was detected in about 15% and 12% of the samples analyzed, respectively. In suspended particulate matter, glyphosate was found in 67% while AMPA was present in 20% of the samples. In streams sediment glyphosate and AMPA were also detected in 66% and 88.5% of the samples respectively. This study is, to our knowledge, the first dealing with glyphosate fate in agricultural soils in Argentina. In the present study, it was demonstrated that glyphosate and AMPA are present in soils under agricultural activity. It was also found that in stream samples the presence of glyphosate and AMPA is relatively more frequent in suspended particulate matter and sediment than in water., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The determination of glyphosate (GLY) in soils is of great interest due to the widespread use of this herbicide and the need of assessing its impact on the soil/water environment. However, its residue determination is very problematic especially in soils with high organic matter content, where strong interferences are normally observed, and because of the particular physico-chemical characteristics of this polar/ionic herbicide. In the present work, we have improved previous LC-MS/MS analytical methodology reported for GLY and its main metabolite AMPA in order to be applied to "difficult" soils, like those commonly found in South-America, where this herbicide is extensively used in large areas devoted to soya or maize, among other crops. The method is based on derivatization with FMOC followed by LC-MS/MS analysis, using triple quadrupole. After extraction with potassium hydroxide, a combination of extract dilution, adjustment to appropriate pH, and solid phase extraction (SPE) clean-up was applied to minimize the strong interferences observed. Despite the clean-up performed, the use of isotope labelled glyphosate as internal standard (ILIS) was necessary for the correction of matrix effects and to compensate for any error occurring during sample processing. The analytical methodology was satisfactorily validated in four soils from Colombia and Argentina fortified at 0.5 and 5mg/kg. In contrast to most LC-MS/MS methods, where the acquisition of two transitions is recommended, monitoring all available transitions was required for confirmation of positive samples, as some of them were interfered by unknown soil components. This was observed not only for GLY and AMPA but also for the ILIS. Analysis by QTOF MS was useful to confirm the presence of interferent compounds that shared the same nominal mass of analytes as well as some of their main product ions. Therefore, the selection of specific transitions was crucial to avoid interferences. The methodology developed was applied to the analysis of 26 soils from different areas of Colombia and Argentina, and the method robustness was demonstrated by analysis of quality control samples along 4 months., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Leaching of the strongly sorbing pesticides glyphosate and pendimethalin was evaluated in an 8-month field study focussing on preferential flow and particle-facilitated transport, both of which may enhance the leaching of such pesticides in structured soils. Glyphosate mainly sorbs to mineral sorption sites, while pendimethalin mainly sorbs to organic sorption sites. The two pesticides were applied in equal dosage to a structured, tile-drained soil, and the concentration of the pesticides was then measured in drainage water sampled flow-proportionally. The leaching pattern of glyphosate resembled that of pendimethalin, suggesting that the leaching potential of pesticides sorbed to either the inorganic or organic soil fractions is high in structured soils. Both glyphosate and pendimethalin leached from the root zone, with the average concentration in the drainage water being 3.5 and 2.7 μg L(-1), respectively. Particle-facilitated transport (particles >0.24 μm) accounted for only a small proportion of the observed leaching (13-16% for glyphosate and 16-31% for pendimethalin). Drain-connected macropores located above or in the vicinity of the drains facilitated very rapid transport of pesticide to the drains. That the concentration of glyphosate and pendimethalin in the drainage water remained high (>0.1 μg L(-1)) for up to 7d after a precipitation event indicates that macropores between the drains connected to underlying fractures were able to transport strongly sorbing pesticides in the dissolved phase. Lateral transport of dissolved pesticide via such discontinuities implies that strongly sorbing pesticides such as glyphosate and pendimethalin could potentially be present in high concentrations (>0.1 μg L(-1)) in both water originating from the drainage system and the shallow groundwater located at the depth of the drainage system., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Degradation of pesticides in soils is both spatially variable and also one of the most sensitive factors determining losses to surface water and groundwater. To date, no general guidance is available on suitable approaches for dealing with spatial variation in pesticide degradation in catchment or regional scale modeling applications. The purpose of the study was therefore to study the influence of various soil physical, chemical and microbiological characteristics on pesticide persistence in the contrasting cultivated soils found in a small (13 km(2)) agricultural catchment in Sweden and to develop and test a simple model approach that could support catchment scale modeling. Persistence of bentazone, glyphosate and isoproturon was investigated in laboratory incubation experiments. Degradation rate constants were highly variable with coefficients of variation ranging between 42 and 64% for the three herbicides. Multiple linear regression analysis and Mallows Cp statistic were employed to select the best set of independent parameters accounting for the variation in degradation. Soil pH and the proportion of active microorganisms (r) together explained 69% of the variation in the bentazone degradation rate constant; the Freundlich sorption co-efficient (K(f)) and soil laccase activity together explained 88% of the variation in degradation rate of glyphosate, while soil pH was a significant predictor (p<0.05) for isoproturon persistence. However, correlations between many potential predictor variables made clear interpretations of the statistical analysis difficult. Multiplicative models based on two predictors chosen 'a priori', one accounting for microbial activity (e.g. microbial respiration, laccase activity or the surrogate variable soil organic carbon, SOC) and one accounting for the effects of sorption on bioavailability, showed promise to support predictions of degradation for large-scale modeling applications, explaining up to 50% of the variation in herbicide persistence., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A systematic investigation into lowered degradation rates of glyphosate in metal-contaminated soils was performed by measuring mineralization of [(14)C]glyphosate to (14)CO(2) in two mineral soils that had been spiked with Cu and/or Zn at various loadings. Cumulative (14)CO(2) release was estimated to be approximately 6% or less of the amount of [(14)C]glyphosate originally added in both soils over an 80-d incubation. For all but the highest Cu treatments (400 mg kg(-1)) in the coarse-textured Arkport soil, mineralization began without a lag phase and declined over time. No inhibition of mineralization was observed for Zn up to 400 mg kg(-1) in either soil, suggesting differential sensitivity of glyphosate mineralization to the types of metal and soil. Interestingly, Zn appeared to alleviate high-Cu inhibition of mineralization in the Arkport soil. The protective role of Zn against Cu toxicity was also observed in the pure culture study with Pseudomonas aeruginosa, suggesting that increased mineralization rates in high Cu soil with Zn additions might have been due to alleviation of cellular toxicity by Zn rather than a mineralization specific mechanism. Extensive use of glyphosate combined with its reduced degradation in Cu-contaminated, coarse-textured soils may increase glyphosate persistence in soil and consequently facilitate Cu and glyphosate mobilization in the soil environment., (Copyright © 2010 SETAC.)

The aim of this study was to investigate the behavior of the association between atrazine and glyphosate in the soil through mineralization and degradation tests. Soil treatments consisted of the combination of a field dose of glyphosate (2.88 kg ha⁻¹) with 0, ½, 1 and 2 times a field dose of atrazine (3.00 kg ha⁻¹) and a field dose of atrazine with 0, ½, 1 and 2 times a field dose of glyphosate. The herbicide mineralization rates were measured after 0, 3, 7, 14, 21, 28, 35, 42, 49, 56 and 63 days of soil application, and degradation rates after 0, 7, 28 and 63 days. Although glyphosate mineralization rate was higher in the presence of 1 (one) dose of atrazine when compared with glyphosate alone, no significant differences were found when half or twice the atrazine dose was applied, meaning that differences in glyphosate mineralization rates cannot be attributed to the presence of atrazine. On the other hand, the influence of glyphosate on atrazine mineralization was evident, since increasing doses of glyphosate increased the atrazine mineralization rate and the lowest dose of glyphosate accelerated atrazine degradation.

The effects of sewage sludge on soil quality with regard to its nutrient and heavy metal content, microbial community structure and ability to maintain specific soil function (degradation of herbicide glyphosate) were investigated in a three months study using an alluvial soil (Eutric Fluvisol). Dehydrated sewage sludge significantly increased soil organic matter (up to 20.6% of initial content), total and available forms of N (up to 33% and 220% of initial amount, respectively), as well as total and plant available forms of P (up to 11% and 170% of initial amount, respectively) and K (up to 70% and 47% of initial amount, respectively) in the upper 2 cm soil layer. The increase of organic matter was most prominent 3d after the application of sewage sludge, after 3 months it was no longer significant. Contents of nutrients kept to be significantly higher in the sewage sludge treated soil till the end of experiment. Contents of some heavy metals (Zn, Cu, Pb) increased as well. The highest increase was found for Zn (up to 53% of initial amount), however it was strongly bound to soil particles and its total content was kept below the maximum permissible limit for agricultural soil. Based on molecular fingerprinting of bacterial 16S rRNA gene and fungal ITS fragment on 3rd day and 3rd month after sewage sludge amendment, significant short term effects on bacterial and fungal communities were shown due to the sewage sludge. The effects were more pronounced and more long-term for bacterial than fungal communities. The mineralization of (14)C-glyphosate in the sewage sludge soil was 55.6% higher than in the control which can be linked to (i) a higher glyphosate bioavailability in sewage sludge soil, which was triggered by the pre-sorption of phosphate originating from the sewage sludge and/or (ii) beneficial alterations of the sewage sludge to the physical-chemical characteristics of the soil., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Biodegradation of glyphosate in sod-podzol soil by both the indigenous micro flora and the introduced strain Ochrobactrum anthropi GPK 3 was studied with respect to its sorption and mobility. The experiments were carried out in columns simulating the vertical soil profile. Soil samples studied were taken from soil horizons 0-10, 10-20, and 20-30 cm deep. It was found out that the most of the herbicide (up to 84%) was adsorbed by soil during the first 24 h; the rest (16%) remained in the soluble fraction. The adsorbed glyphosate was completely extractable by alkali. No irreversible binding of glyphosate was observed. By the end of the experiment (21st day), glyphosate was only found in extractable fractions. The comparison of the effect of the introduced O. anthropi GPK 3 and indigenous microbial community on the total toxicant content (both soluble and absorbed) in the upper 10 cm soil layer showed its reduction by 42% (21 mg/kg soil) and 10-12% (5 mg/kg soil), respectively. Simultaneously, 14-18% glyphosate moved to a lower 10-20 cm layer. Watering (that simulated rainfall) resulted in a 20% increase of its content at this depth; 6-8% of herbicide was further washed down to the 20-30 cm layer. The glyphosate mobility down the soil profile reduced its density in the upper layer, where it was available for biodegradation, and resulted in its concentration in lower horizons characterized by the absence (or low level) of biodegradative processes. It was shown for the first time how the herbicide biodegradation in soil can be increased manifold by introduction of the selected strain O. anthropi GPK 3.

The transport of Glyphosate ([N-phosphonomethyl] glycine), AMPA (aminomethylphosphonic acid, CH(6)NO(3)P), and Bromide (Br(-)) has been studied, in the Mediterranean Maresme area of Spain, north of Barcelona, where groundwater is located at a depth of 5.5m. The unsaturated zone of weathered - granite soils was characterized in adjacent irrigated and non-irrigated experimental plots where 11 and 10 boreholes were drilled, respectively. At the non irrigated plot, the first half of the period was affected by a persistent and intense rainfall. After 69 days of application residues of Glyphosate up to 73.6 microgg(-1) were detected till a depth of 0.5m under irrigated conditions, AMPA, analyzed only in the irrigated plot was detected till a depth of 0.5m. According to the retardation coefficient of Glyphosate as compared to that of Br(-) for the topsoil and subsoil (80 and 83, respectively) and the maximum observed migration depth of Br(-) (2.9 m) Glyphosate and AMPA should have been detected till a depth of 0.05 m only. Such migration could be related to the low content of organic matter and clays in the soils; recharge generated by irrigation and heavy rain, and possible preferential solute transport and/or colloidal mediated transport., (Copyright 2010 Elsevier B.V. All rights reserved.)

The leaching of soil particles and surface applied 14C-labeled glyphosate and pendimethalin from intact soil columns (height: 50 cm; diameter: 30 cm) were investigated, and the relative significance of particle-facilitated pesticide transport was quantified. Investigations were performed with a recently plowed (four columns) and an untilled (five columns) sandy loam soil. Leaching was driven by three irrigation events (15 mm h(-1); 2 h each). Samples of the leachate were filtered immediately (within 1.5 minutes) using 20 nm filters, and the 14C-pesticide content was determined for filtered and unfiltered samples. Pesticide leaching was driven by preferential water flow in macropores. For the plowed structure, 68+/-10% of the leached glyphosate (average of 6 events+/-std.) was bound to particles whereas significantly less glyphosate was bound to particles in leachate from minimally disturbed columns (17+/-12%). Thus, the results suggest that soil structure affected the mode of transport of glyphosate. It is likely that glyphosate sorbed strongly when applied on recently plowed soil (Kd=503 L kg(-1) for the soil), and that it could be mobilized and transported independently of soil particles more easily when applied on the minimally disturbed soil covered in part with crop residues (Kd<1 L kg(-1) for straw). Significantly less amounts of soil particles were leached from minimally disturbed (119-247 mg) than from recently plowed (441-731 mg) columns. The significance of particle-facilitated pendimethalin leaching could not be accurately quantified due to disagreement between control measurements based on both 14C-activity and chemical analyses.

The bioaccumulation potential of glyphosate and the formulation Roundup Ultra, as well as possible effects on biotransformation and antioxidant enzymes in Lumbriculus variegatus were compared by four days exposure to concentrations between 0.05 and 5 mg L(-1) pure glyphosate and its formulation. Bioaccumulation was determined using (14)C labeled glyphosate. The bioaccumulation factor (BCF) varied between 1.4 and 5.9 for the different concentrations, and was higher than estimated from logP(ow). Glyphosate and its surfactant POEA caused elevation of biotransformation enzyme soluble glutathione S-transferase at non-toxic concentrations. Membrane bound glutathione S-transferase activity was significantly elevated in Roundup Ultra exposed worms, compared to treatment with equal glyphosate concentrations, but did not significantly differ from the control. Antioxidant enzyme superoxide dismutase was significantly increased by glyphosate but in particular by Roundup Ultra exposure indicating oxidative stress. The results show that the formulation Roundup Ultra is of more ecotoxicological relevance than the glyphosate itself.

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1mug/l in all tested profiles while metribuzine always exceeded the 0.1mug/l threshold value.

The fate of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) was studied in soil. Labeled glyphosate was used to be able to distinguish the measured quantities of glyphosate and AMPA from the background values since the soil was sampled in a field where glyphosate had been used formerly. After addition of labeled glyphosate, the disappearance of glyphosate and the formation and disappearance of AMPA were monitored. The resulting curves were fitted according to a new EU guideline. The best fit of the glyphosate degradation data was obtained using a first-order multi compartment (FOMC) model. DT(50) values of 9 days (glyphosate) and 32 days (AMPA) indicated relatively rapid degradation. After an aging period of 6 months, the leaching risk of each residue was determined by treating the soil with pure water or a phosphate solution (pH 6), to simulate rain over a non-fertilized or fertilized field, respectively. Significantly larger (p < 0.05) amounts of aged glyphosate and AMPA were extracted from the soil when phosphate solution was used as an extraction agent, compared with pure water. This indicates that the risk of leaching of aged glyphosate and AMPA residues from soil is greater in fertilized soil. The blank soil, to which 252 g glyphosate/ha was applied 21 months before this study, contained 0.81 ng glyphosate/g dry soil and 10.46 ng AMPA/g dry soil at the start of the study. Blank soil samples were used as controls without glyphosate addition. After incubation of the blank soil samples for 6 months, a significantly larger amount of AMPA was extracted from the soil treated with phosphate solution than from that treated with pure water. To determine the degree of uptake of aged glyphosate residues by crops growing in the soil, (14)C-labeled glyphosate was applied to soil 6.5 months prior to sowing rape and barley seeds. After 41 days, 0.006 +/- 0.002% and 0.005 +/- 0.001% of the applied radioactivity was measured in rape and barley, respectively.

The fate of organic herbicides applied to agricultural fields may be affected by other soil amendments, such as copper applied as a fungicide. The effect of copper on the leaching of diuron and glyphosate through a granitic and a calcareous soil was studied in the laboratory using sieved-soil columns. Each soil was enriched with copper sulfate to obtain soil copper concentrations of 125, 250, 500, and 1000 mg kg(-1). Glyphosate leaching was influenced by soil pH and copper concentration, whereas diuron leaching was not. In the calcareous soil, glyphosate leaching decreased as copper levels increased from 17 mg kg(-1) (background) to 500 mg kg(-1). In the granitic soil, glyphosate leaching increased as copper levels increased from 34 mg kg(-1) (background) to 500 mg kg(-1). The shapes of the copper elution curves in presence of glyphosate were similar to shapes of the glyphosate curves, suggesting the formation of Cu-glyphosate complexes that leach through the soil. Soil copper concentration does not influence diuron leaching. In contrast, increasing copper concentrations reduces glyphosate leaching through calcareous soils, and conversely, increases glyphosate leaching through granitic soils. Our findings suggest that the risk of groundwater contamination by glyphosate increases in granitic soils with elevated copper concentrations.

Indirect soil pollution by heavy metals and organics may occur when sewage sludge is used as fertilizer. It is essential to define the nature and amounts of pollutants contained in sewage sludge in order to assess environmental risk. Here, we present results from a one-year monitoring of herbicides (glyphosate, diuron and atrazine) and their major degradates in sewage sludge sampled from three wastewater treatment plants and one composting unit in the vicinity of Versailles, France. The concentrations of these compounds were determined, as well as these of the surfactant nonylphenol. We demonstrated the presence of glyphosate and aminomethylphosphonic acid at the mg kg(-1) (dry matter) level in all samples. Diuron was detected at the microg kg(-1) (d.m.) level, whereas its degradate and triazine compounds were below the limits of quantification. Nonylphenol amounts were higher than the future European limit value of 50 mg kg(-1) (d.m.).

Agricultural application of large amounts of glyphosate [N-(phosphonomethyl)-glycine] may affect soil metal behaviors to some extend, because glyphosate can react with many kinds of metals to form metal complexes. Cosorption of Zn and glyphosate on a Red soil (RS, Udic Ferrosols) and a Wushan soil (WS, Anthrosol) was studied. In comparison with the WS, the RS has less adsorption capacity for Zn and higher for glyphosate. The presence of glyphosate decreased Zn adsorption on the two soils, which are resulted from the decreased equilibrium solution pH caused by the added glyphosate, and also the formation of water-soluble complexes of glyphosate with solution Zn(2+) that had lower affinity to soil surface in comparison with Zn(2+) itself. Such effect is more significant on the RS than on the WS, mainly because of the less adsorption quantity of Zn on the former one. On the contrary, the presence of Zn increased the adsorption quantities of glyphosate on the RS and WS, which is resulted from the decreasing pH value of the equilibrium solution caused by Zn(2+) exchange with H(+) ions of soil surface. Such results suggest that glyphosate in field may increase the mobility and bioavailability of Zn and correspondingly increase its environmental risk.

The vertical distribution of the sorption, desorption and mineralisation of glyphosate and MCPA was examined in samples from two contrasting soil and subsurface profiles, obtained from a sandy agricultural site and a non-agricultural clay rich site. The highest mineralisation of [14C-methylen]glyphosate, with 9.3-14.7% degraded to 14CO2 within 3 months was found in the deepest sample from the clay site. In the deeper parts of the sandy profile high sorption and low desorption of glyphosate coincided with no or minor mineralisation indicating a limited glyphosate bioavailability. MCPA was readily mineralised except in the deepest samples from both sites. The highest MCPA mineralisation was detected just below the surface layers with 72% or 44% degraded to 14CO2 at the sandy or the clay sites, respectively. MCPA sorped to a minor extent in all samples and no indications of sorption-controlled mineralisation was revealed. None of the herbicides were mineralised under anoxic conditions.

Some drinking water reservoirs under the vineyards of Burgundy are contaminated with herbicides. Thus the effectiveness of alternative soil management practices, such as grass cover, for reducing the leaching of glyphosate and its metabolite, AMPA, through soils was studied. The leaching of both molecules was studied in structured soil columns under outdoor conditions for 1 year. The soil was managed under two vineyard soil practices: a chemically treated bare calcosol, and a vegetated calcosol. After 680 mm of rainfall, the vegetated calcosol leachates contained lower amounts of glyphosate and AMPA (0.02% and 0.03%, respectively) than the bare calcosol leachates (0.06% and 0.15%, respectively). No glyphosate and only low amounts of AMPA (<0.01%) were extracted from the soil. Glyphosate, and to a greater extent, AMPA, leach through the soils; thus, both molecules may be potential contaminants of groundwater. However, the alternative soil management practice of grass cover could reduce groundwater contamination by the pesticide.

This paper describes a method for the sensitive and selective determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) residues in water and soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate (FMOC) in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the case of water samples a volume of 10 mL was derivatized and then 4.3 mL of the derivatized mixture was directly injected in an on-line solid phase extraction (SPE)-LC-MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column. Soil samples were firstly extracted with potassium hydroxide. After that, the aqueous extract was 10-fold diluted with water and 2 mL were derivatized. Then, 50 microL of the derivatized 10-fold diluted extract were injected into the LC-MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at 50 and 500 ng/L, and also in soil samples, spiked at 0.05 and 0.5 mg/kg. In water samples, the mean recovery values ranged from 89 to 106% for glyphosate (RSD <9%), from 97 to 116% for AMPA (RSD < 10%), and from 72 to 88% in the case of glufosinate (RSD < 12%). Regarding soil samples, the mean recovery values ranged from 90 to 92% for glyphosate (RSD <7%), from 88 to 89% for AMPA (RSD <5%) and from 83 to 86% for glufosinate (RSD <6%). Limits of quantification for all the three compounds were 50 ng/L and 0.05 mg/kg in water and soil, respectively, with limits of detection as low as 5 ng/L, in water, and 5 microg/kg, in soil. The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA, while it was not efficient for glufosinate, that was quantified by external standards calibration. The method developed has been applied to the determination of these compounds in real water and soil samples from different areas. All the detections were confirmed by acquiring two transitions for each compound.

Contributions of organic matter and minerals in soil were evaluated by comparing changes in adsorption of methamidophos (MDP) and glyphosate (GPS) before and after removal of organic matter from argaltoll (mollisol) and typustalf (alfisol) soils. Adsorption isotherms of MDP and GPS by the two soils comforted to Freundlich equation, and the adsorption capacity of GPS by argaltoll soil was higher than that of MDP. Due to the removal of organic matter from soils, K(f) values of MDP and GPS adsorbed by argaltoll soil, which were calculated from Freundlich equations and the measure of adsorption capacity, decreased by 46.1% and 75.0%, and these by typustalf soil decreased by 34.9% and 52.5%, respectively. Results from this study suggested that soil organic matter made greater contributions to adsorption of GPS, but soil minerals could provide more available adsorption sites for MDP.