Usefulness of oxidative stress biomarkers in native species for the biomonitoring of pesticide pollution in a shallow lake of the Austral Pampas, Argentina.

Pesticide contamination and its adverse effects on native freshwater species continue to be a worldwide major concern, mainly in developing countries. Passive biomonitoring of pesticide pollution in shallow lakes may be achieved by the simultaneous use of fish and wetland plants. Thus, the present study aimed to evaluate the occurrence of current-use pesticides in the surface water of a shallow lake of the Austral Pampas region (Buenos Aires Province, Argentina) surrounded by intensive agricultural activities and its relationship with a battery of biomarkers, including oxidative stress and genotoxicity, in two native species, the fish Oligosarcus jenynsii and the macrophyte Bidens laevis. A total of 26 pesticide residues were analyzed, and the main ones detected were glyphosate and its metabolite aminomethylphosphonic acid (AMPA), chlorpyrifos, and imidacloprid. In O. jenynsii, hydrogen peroxide (H2O2) content in the liver increased with chlorpyrifos occurrence, while malondialdehyde (MDA) levels in the brain and liver increased with the presence of both chlorpyrifos and glyphosate. In B. laevis, H2O2 and MDA levels in leaves and roots increased with AMPA occurrence. Also, leaf H2O2 contents and root MDA levels increased with chlorpyrifos concentration. In contrast, catalase and peroxidase activities in roots decreased with AMPA and chlorpyrifos occurrence. In both species, mainly H2O2 and MDA levels demonstrated their sensitivity to be used as biomarkers in the biomonitoring of current-use pesticide pollution in shallow lakes. Their use may provide information to plan strategies for environmental conservation by government institutions or decision-makers, and to assess the biota health status.

Fertilisation of agricultural soils with municipal biosolids: Glyphosate and aminomethylphosphonic acid inputs to Québec field crop soils.

Municipal biosolids (MBS) are suggested to be abundant, sustainable, inexpensive fertilisers, rich in phosphorus and nitrogen. However, MBS can also contain glyphosate and phosphonates that can degrade to AMPA. Glyphosate-based herbicides (GBH) are used in field crops all over the world. Most glyphosate generally degrades within a few weeks, mainly as aminomethylphosphonic acid (AMPA). AMPA is more persistent than glyphosate, and can accumulate from one crop year to the next. AMPA is phytotoxic even to glyphosate-resistant crops. The aims of this study were to assess whether MBS applications constitute: 1) an additional source of glyphosate and AMPA to agricultural soils with respect to GBH, 2) a significant source of trace metals, and 3) a partial replacement of mineral fertilisation while maintaining similar yields. To this end, four experimental agricultural sites were selected in Québec (Canada). Soil samples (0-20 cm) were collected to estimate the as yet unmeasured contribution of MBS application to glyphosate and AMPA inputs in agricultural soils. MBS applied in 2021 and 2022 had mean concentrations of 0.69 ± 0.53 µg glyphosate/dry g and 6.26 ± 1.93 µg AMPA/dry g. Despite the presence of glyphosate and AMPA in MBS, monitoring of these two compounds in corn and soybean crops over two years showed no significant difference between plots treated with and without MBS applications. For the same site, yields measured at harvest were similar between treatments. MBS application could thus represent a partial alternative to mineral fertilisers for field crops, while limiting the economic and environmental costs associated with their incineration and landfilling. It is also an economic advantage for agricultural producers given the possibility of using fewer mineral fertilisers and therefore reducing the environmental impact of their use.

Quantitation of glyphosate, glufosinate, and AMPA in drinking water and surface waters using direct injection and charged-surface ultra-high performance liquid chromatography-tandem mass spectrometry.

Herbicides glyphosate (N-(phosphonomethyl)glycine) and glufosinate (2-amino-4-(hydroxymethylphosphinyl)butanoic acid) and the main transformation product of glyphosate, aminomethanephosphonic acid (AMPA), are challenging to analyze for in environmental samples. The quantitative method developed by this study adapts previously standardized dechlorination procedures coupled to a novel charged surface C18 column, ultra-high performance liquid chromatography-tandem mass spectrometry, polarity switching, and direct injection. The method was applied to chlorinated tap water, as well as river samples, collected in the City of Winnipeg and rural Manitoba, Canada. Using only syringe filtration without derivatization, the validated method resulted in good accuracies in both tap and surface water, at both 2 and 20 µg L-1. Method limits of detection (MLD) and quantification (MLQ) ranged from 0.022/0.074 to 0.11/0.36 µg L-1, with precisions of 0.46-2.2% (intraday) and 1.3-7.3% (interday). The mean (SEM) of the pesticides in µg L-1 for tap water were 0.11 (0.007) (AMPA), glufosinate and glyphosate < MLDs; and for Red River water were 0.56 (0.045) (AMPA), glufosinate < MLQ, and glyphosate 0.40 (0.072). For the smaller tributaries, glufosinate was >MLD but < MLQ once and that was for Shannon Creek at 0.2 µg L-1. For the remaining rivers, the mean concentrations ranged from 0.31 to 3.1 µg L-1 for AMPA, and 0.087-0.53 µg L-1 for glyphosate. The method will be ideal for supporting monitoring and risk assessment programs that require high throughput sampling and quantitative methods capable of producing robust results that leverages chromatographic and mass spectrometric paradigms instead of being extraction technology focused.

Biomonitoring of glyphosate and aminomethylphosphonic acid: Current insights and future perspectives.

Glyphosate is one of the most widely used herbicides globally, raising concerns about its potential impact on human health. Biomonitoring studies play a crucial role in assessing human exposure to glyphosate and providing valuable insights into its distribution and metabolism in the body. This review aims to summarize the current trends and future perspectives in biomonitoring of glyphosate and its major degradation product of aminomethylphosphonic acid (AMPA). A comprehensive literature search was conducted, focusing on studies published between January 2000 and December 2022. The findings demonstrated that glyphosate and AMPA have been reported in different human specimens with urine as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with liquid/gas chromatography-tandem mass spectrometry have achieved matrix elimination and accurate analysis. We also examined and compared the exposure characteristics of these compounds among different regions and various populations, with significantly higher levels of glyphosate and AMPA observed in Asian populations and among occupational groups. The median urinary concentration of glyphosate in children was 0.54 ng/mL, which was relatively higher than those in women (0.28 ng/mL) and adults (0.12 ng/mL). It is worth noting that children may exhibit increased susceptibility to glyphosate exposure or have different exposure patterns compared to women and adults. A number of important perspectives were proposed in order to further facilitate the understanding of health effects of glyphosate and AMPA, which include, but are not limited to, method standardization, combined exposure assessment, attention for vulnerable populations, long-term exposure effects and risk communication and public awareness.

Cocktails of pesticide residues in Prochilodus lineatus fish of the Salado River (South America): First record of high concentrations of polar herbicides.

Muscle and viscera (gills-liver) of the fish Prochilodus lineatus were obtained from four sites of lower course of Salado river and one site at Santa Fe river near to its confluence with Salado river from Santa Fe (Argentina) between December 2021 and February 2022. Sediment samples were also obtained from the same sites. All samples were analyzed for pesticide residues following the QuEChERS method to quantify 136 compounds by UHPLC-ESI-MS/MS and GC-EI-MS/MS. Overall, muscle fish tissue showed very high concentrations (maximum concentrations detected) of the insecticide cypermethrin (204 µg/kg), polar herbicides (glyphosate; 187 µg/kg and its degradation product (aminomethylphosphonic acid) AMPA; 3116 µg/kg, and glufosinate-ammonium; 677 µg/kg), and the fungicide pyraclostrobin (50 µg/kg). In viscera samples, high values of cypermethrin (506 µg/kg), chlorpyrifos (78 µg/kg), and lambdacyhalothrin (73 µg/kg) were the main pesticides found. Mean residues concentrations detected among sites were not significantly different neither in muscle nor viscera of P. lineatus in most of the cases. Exceptionally, the southernmost studied site of the Lower Salado river showed significant differences in concentration of residues found in muscle, due to high concentrations of glyphosate and glufosinate-amonium (KW = 11.879 and KW = 13.013, respectively, P < 0.05). Other norther Lower Salado river site showed significant higher AMPA concentration in fish viscera than in the rest of the studied sites (KW = 12.86 P < 0.05). Some sediment samples showed low levels of herbicides such as glyphosate (24 µg/kg) and fungicides. However, the world highest levels of polar herbicides were recorded in fish muscle. The results of this study highlight the need for periodic monitoring due to the high concentration of pesticides and its potential risk in a very important commercial freshwater fish from Argentina, which is consumed locally and exported to other countries for human consumption.

Direct, automated and sensitive determination of glyphosate and related anionic pesticides in environmental water samples using solid-phase extraction on-line combined with liquid chromatography tandem mass spectrometry.

An automated procedure for the simultaneous determination of six anionic pesticides, including glyphosate (GLY) and its transformation product aminomethylphosphonic acid (AMPA), was developed and applied to the analysis of environmental water samples. The proposed method combines on-line concentration of water samples (0.160 mL), with compounds separation in an anion-exchange liquid chromatography (LC) column, followed by their selective determination by tandem mass spectrometry (MS/MS). The global procedure was completed in 25 min, providing limits of quantification (LOQs) between 5 ng L-1 and 20 ng L-1, with reduced effect of the surface water matrix in the efficiency of process (SPE and ionization yields). The method was applied to the analysis of grab samples obtained from three watersheds, in two rural and one residential area, in Galicia (Northwest Spain). Out of six investigated compounds, Fosetyl, AMPA and GLY were noticed in the set of processed samples. Their detection frequencies increased from 12% (Fosetyl) to 88% (AMPA). Median concentrations followed the same trend varying from 9 ng L-1 (Fosetyl) to 44 ng L-1 (AMPA). The higher levels and the large seasonal variations in the residues of the latter species were noticed in small rivers affected by discharges of municipal sewage treatment plants (STPs).

Higher proportion of agricultural land use around the residence is associated with higher urinary concentrations of AMPA, a glyphosate metabolite.

INTRODUCTION: Pesticides, including herbicides, are widely used for agricultural and sanitary reasons and concerns have been raised about their various health effects. Little research has been done into the extent to which agricultural land use in the residential surroundings contributes to (internal) exposure of pesticides. OBJECTIVES: We investigated the associations between the proportion of agricultural land use around the residence and the exposure to pesticides in adolescents in Flanders (Belgium). MATERIAL AND METHODS: We included 424 adolescents participating in the fourth Flemish Environment and Health Study (FLEHS IV) between 2016 and 2020. The residential address of all participants was geocoded and the proportion of agricultural land use around the residence was estimated in several buffers (300 m, 500 m, 1000 m and 2000 m). The concentrations of the following biomarkers of pesticides were measured in urine and adjusted for the specific gravity: glyphosate and its metabolite, aminomethyl-phosphonic acid (AMPA); 3-phenoxybenzoic acid (3-PBA); 3,5,6-trichloro-2-pyridinol (TCPy) and 2,4-dichlophenoxy-acetic acid (2,4-D). We categorized the pesticide biomarkers in three categories according to the exposure levels and used ordinal logistic regression models adjusted for sex, season and household education to estimate the odds ratio for an increase in an interquartile range (IQR) of proportion of agricultural land use. We also used binary logistic regression models in which the category of highest exposure was compared to the category of lowest exposure. In addition, we explored potential effect modification by sex and season. RESULTS: We found a significant association between the proportion of agricultural land use in a buffer of 2000 m around the residence and the levels of urinary AMPA divided into three categories (OR = 1.35 for an IQR increase in the proportion of agricultural land use around residence; 95% CI: 1.00-1.83). This association was less pronounced and not statistically significant for the other studied pesticides (OR ranging between 0.95 and 1.16). Stratified analysis showed the strongest association of the proportion of agricultural land use within 2000 m buffers for AMPA among boys (OR = 1.89; 95% CI: 1.19-3.04). Results using smaller buffers were comparable, but did not reach statistical significance. CONCLUSION: Our findings suggest that a higher proportion of agricultural land use around the residence might increase exposure to AMPA.

Method of Glyphosate, AMPA, and Glufosinate Ammonium Determination in Beebread by Liquid Chromatography-Tandem Mass Spectrometry after Molecularly Imprinted Solid-Phase Extraction.

The aim of this study was to develop a method for the determination of glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and glufosinate ammonium residues in beebread samples, which could then be used to assess bees' exposure to their residues. The complexity of beebread's matrix, combined with the specific properties of glyphosate itself, required careful selection and optimization of each analysis step. The use of molecularly imprinted solid-phase extraction (MIP-SPE) by AFFINIMIP glyphosate as an initial clean-up step significantly eliminated matrix components and ensured an efficient derivatization step. Colorless beebread extracts were derivatized by the addition of 9-fluorenylmethyl chloroformate (FMOC-Cl). After derivatization, in order to remove FMOC-OH and residual borate buffer, a solid-phase extraction (SPE) clean-up step using Oasis HLB was carried out. Instrumental analysis was performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The method was validated according to the SANTE/11312/2021 guideline at concentrations of 5, 10, and 100 µg/kg, and satisfactory recovery (trueness) values (76-111%) and precision (RSDr) ≤ 18% were obtained. The limit of quantification (LOQ) was 5 µg/kg for AMPA and glufosinate ammonium and 10 µg/kg for glyphosate. The method was positively verified by the international proficiency test. Analysis of beebread samples showed the method's usefulness in practice. The developed method could be a reliable tool for the assessment of beebread's contamination with residues of glyphosate, its metabolite AMPA, and glufosinate ammonium.

Assessment of bioaccumulation of glyphosate and aminomethylphosphonic acid in marine mussels using capillary electrophoresis with light-emitting diode-induced fluorescence detection.

Glyphosate or N-(phosphonomethyl)glycine, widely used as herbicide in agriculture to control weeds and to facilitate harvesting, has been included in Group 2A pollutants (probably carcinogenic to humans) by the International Agency for Research on Cancer (IARC). In intensive agricultural areas, runoff and soil leaching are likely to drive glyphosate to surface waters, where the compound is often detected together with its main microbial metabolite, aminomethylphosphonic acid (AMPA). In the present study a method based on capillary electrophoresis coupled with light-emitting diode-induced fluorescence detection has been developed and validated for the determination of the two compounds in whole soft mass of marine mussels (Mytilus galloprovincialis). The method is based on the acidic hydrolysis of lyophilized tissue using 6 M HCl (oven at 110 °C for 22 h) to release the target analytes; their subsequent derivatization using 4-fluoro-7-nitro-2,1,3-benzoxadiazole, was found to be suitable for the sensitive fluorescence detection. To achieve optimum separation of the analytes from the matrix and degradation reagent interferences, the background electrolyte constituted by borate buffer (pH 9.2, 30 mM) was supplemented with 10 mM heptakis(2,6-di-O-methyl)-ß-cyclodextrin. The method was validated for linearity, precision, accuracy, robustness and sensitivity showing LOQ of 0.2 and 1.0 µg/g in fresh tissues, for AMPA and glyphosate, respectively; the recovery values ranged within 88.5 - 94.6% for glyphosate and 70.4 - 76.6% for AMPA. Experimental samples of Mediterranean mussels M. galloprovincialis treated with 100 µg/L or 500 µg/L of both glyphosate and AMPA, showed a dose dependent bioaccumulation of the compounds reaching maximum level of 77.0 µg/g and 11.3 µg/g of AMPA and glyphosate, respectively. The study demonstrates for the first time M. galloprovincialis as potential sentinel organisms for the environmental occurrence of these small amphoteric pollutants.

Evaluation of pesticide pollution in the Gualeguay Basin: An extensive agriculture area in Argentina.

The current agricultural production model was established in the 1990s based on the use of genetically modified organisms and agrochemicals, mainly pesticides. Despite pesticide spread and prevalence, data on the associated concentrations in surface watercourses are comparatively scarce. The aim of this work was to evaluate to what extent the >20 years of agricultural activity with the use of pesticides has impacted on the Gualeguay-River basin, with respect to the different stream orders: the tributary streams and main channel. Thirteen sites within the lower Gualeguay basin were sampled once every season (autumn, winter, spring, and summer) in 2017-2018. The samples were analyzed by gas chromatography time-of-flight mass-spectrometry (GC-TOF-MS) and ultraperformance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). The most frequently detected pesticide was glyphosate along with its metabolite (aminomethyl)phosphonic acid (AMPA), at 82 % and 71 % of surface water samples and 97 % and 92 % of bottom sediments, respectively; followed by atrazine in 73 % of the water samples. The concentrations of these compounds, each in their respective matrices, did not present sufficient statistically significant differences for differentiating a tributary stream from the main channel. Regardless of glyphosate's affinity for the suspended particulate and bottom sediments, over the entire basin the soluble fraction contributed on average to >80 % of the total concentration in surface water. Despite not being so frequently detected, certain insecticides, mostly deltamethrin, were likewise detected at concentrations above their water-quality guidelines for the protection of aquatic life, even in samples from the main channel. Upon comparison of the pesticide profiles of extensive- and horticultural-production systems in the country, atrazine emerged as a prime candidate to be used as a tracer of extensive agriculture contamination in the environment. Further research is required to establish to what degree pesticides used in agriculture and mobilized by watercourses have an impact on their associated wetland ecosystems.

Glyphosate, AMPA, and metsulfuron-methyl retention in the main horizons of a Typic Argiudoll.

Retention is one of the processes controlling the behavior and fate of pesticides in soil. The objective of this work was to evaluate the adsorption and desorption of glyphosate, AMPA, and metsulfuron-methyl in the main horizons of a Typic Argiudoll destined for agricultural use. For this purpose, the batch equilibrium method was used at a range of concentrations for each compound. Desorption was performed in three consecutive steps after the adsorption experiment. The results obtained showed strong adsorption of glyphosate and AMPA in the three horizons, following the trend B > A > C, with weak desorption. Metsulfuron-methyl, on the other hand, showed weak adsorption in the three horizons, following the trend A > B > C, with relevant desorption. Our results allow us to identify metsulfuron-methyl as the compound that poses the greatest environmental risk in terms of the potential contamination of other areas and groundwater. However, despite their strong adsorption and weak desorption, glyphosate and AMPA also represent potential contaminants of other environmental matrices.

Phosphate addition enhances alkaline extraction of glyphosate from highly sorptive soils and aquatic sediments.

BACKGROUND: Analytical constraints complicate environmental monitoring campaigns of the herbicide glyphosate and its major degradation product aminomethylphosphonic acid (AMPA): their strong sorption to soil minerals requires harsh extraction conditions. Coextracted matrix compounds impair downstream analysis and must be removed before analysis. RESULTS: A new extraction method combined with subsequent capillary electrophoresis-mass spectrometry for derivatization-free analysis of glyphosate and AMPA in soil and sediment was developed and applied to a suite of environmental samples. It was compared to three extraction methods from literature. We show that no extraction medium reaches 100% recovery. The new phosphate-supported alkaline extraction method revealed (1) high recoveries of 70-90% for soils and aquatic sediments, (2) limits of detections below 20 µg kg-1 , and (3) a high robustness, because impairing matrix components (trivalent cations and humic acids) were precipitated prior to the analysis. Soil and sediment samples collected around Tübingen, Germany, revealed maximum glyphosate and AMPA residues of 80 and 2100 µg kg-1 , respectively, with residues observed along a core of lake sediments. Glyphosate and/or AMPA were found in 40% of arable soils and 57% of aquatic sediment samples. CONCLUSION: In this work, we discuss soil parameters that influence (de)sorption and thus extraction. From our results we conclude that residues of glyphosate in environmental samples are easily underestimated. With its possible high throughput, the method presented here can resolve current limitations in monitoring campaigns of glyphosate by addressing soil and aquatic sediment samples with critical sorption characteristics.

Characterization of a novel glyphosate-degrading bacterial species, Chryseobacterium sp. Y16C, and evaluation of its effects on microbial communities in glyphosate-contaminated soil.

Widespread use of the herbicide glyphosate in agriculture has resulted in serious environmental problems. Thus, environment-friendly technological solutions are urgently needed for the removal of residual glyphosate from soil. Here, we successfully isolated a novel bacterial strain, Chryseobacterium sp. Y16C, which efficiently degrades glyphosate and its main metabolite aminomethylphosphonic acid (AMPA). Strain Y16C was found to completely degrade glyphosate at 400 mg·L-1 concentration within four days. Kinetics analysis indicated that glyphosate biodegradation was concentration-dependent, with a maximum specific degradation rate, half-saturation constant, and inhibition constant of 0.91459 d-1, 15.79796 mg·L-1, and 290.28133 mg·L-1, respectively. AMPA was identified as the major degradation product of glyphosate degradation, suggesting that glyphosate was first degraded via cleavage of its C-N bond prior to subsequent metabolic degradation. Strain Y16C was also found to tolerate and degrade AMPA at concentrations up to 800 mg·L-1. Moreover, strain Y16C accelerated glyphosate degradation in soil indirectly by inducing a slight alteration in the diversity and composition of soil microbial community. Taken together, our results suggest that strain Y16C may be a potential microbial agent for bioremediation of glyphosate-contaminated soil.

Determination of Highly Polar and Ionic Pesticides in Grape and Pomegranate Using Liquid Chromatography Tandem Mass Spectrometry.

BACKGROUND: Residues of polar pesticides cannot be determined by QuEChERS-based multiresidue extractions because of their non-amenability to reverse-phase chromatographic separation and poor recoveries. On the other hand, single-residue methods pose limitations because of the various requirements of sample preparation and LC-MS/MS conditions. A new multiresidue method is thus warranted for rapid and simultaneous analysis of polar pesticides. OBJECTIVE: The study developed a multiresidue method for the simultaneous analysis of glyphosate and its metabolite (aminomethylphosphonic acid, AMPA), glufosinate and its metabolites (3-methylphosphinicopropionic acid and N-acetyl-glufosinate), ethephon, fosetyl-aluminum and its metabolite (phosphonic acid), and trimesium in grape and pomegranate by LC-MS/MS. METHOD: The homogenized samples (10 g) were extracted with acidified methanol (20 mL). An aliquot of the extract was diluted with acetonitrile (1 + 1) and measured by LC-MS/MS using a Torus DEA column. The performance of a hydrophilic interaction liquid chromatography (HILIC) column and an "anionic polar pesticides" (APP) column was also evaluated. RESULTS: The method performance on the Torus DEA column was satisfactory for all compounds (recoveries = 77-104%, repeatability-RSD, <11%) at limit of quantification (LOQ) (0.01 mg/kg), and with higher levels in grape and pomegranate. The only exception was AMPA, which had an LOQ of 0.05 mg/kg. In the APP column, AMPA could be determined with an LOQ of 0.01 mg/kg. Trimesium, which had poor retention in Torus DEA, performed better in an XBridge HILIC column (retention time = 4.2 min, LOQ = 0.01 mg/kg). The inter-laboratory validation experiment yielded comparable results with high accuracy and precision. CONCLUSIONS: The method could screen the residues of all compounds on a Torus DEA column. For AMPA and trimesium, the APP and XBridge HILIC columns provided superior method performances. Since isotopically labeled internal standards were not required, the method appeared cost-effective. Considering its compliance with the SANTE/12682/2019 validation guidelines and EU-MRLs, the method can be recommended for regulatory testing purposes. HIGHLIGHTS: A high-throughput residue analysis method targeting nine polar and ionic compounds in grape and pomegranate involved a single multiresidue extraction, followed by direct analysis using LC-MS/MS. A satisfactory method performance was achieved through intra- and inter-laboratory validation. The method sensitivity met the EU-MRLs and the SANTE/12682/2019 analytical quality control criteria.

Glyphosate and AMPA occurrence in agricultural watershed: the case of Paraná Basin 3, Brazil.

Glyphosate is the main herbicide used in soybean crops, and Brazil is one of the major soybean producers around the world. GLY and AMPA were evaluated in 124 surface waters samples of twenty one micro basins in Paraná Basin 3 (State of Parana, Brazil) over six subsequent weeks. A simple and economical routine methodology was established, based on lyophilization as a pre-concentration method. The validated method showed a limit of detection of 0.0125 and 0.025 µg L-1 for GLY and AMPA, respectively. In general, water samples presented concentrations ranging from 0.31 to 1.65 µg L-1 for GLY. Those values are below the maximum allowed amounts in Brazilian Law (65 µg L-1). The AMPA values were found in the range from 0.50 to 1.40 µg L-1. In summary, GLY was detected in 19.3% and it was quantified in 17.7% of the samples. AMPA was detected in 21.8% and it was quantified in 1.6% of the samples. Although samples did not present values higher than the established by Brazilian Law, GLY and AMPA appear constantly in the samples, which highlight the importance of monitoring studies in watersheds.

Determination of glyphosate, AMPA and glufosinate by high performance liquid chromatography with fluorescence detection in waters of the Santarém Plateau, Brazilian Amazon.

Herbicide use, mainly glyphosate, has been intense in worldwide agriculture, including in the Brazilian Amazon region. This study aimed to validate a method for determining glyphosate and its degradation product, AMPA, and glufosinate by HPLC-FL in 58 water samples collected at the Santarém plateau region (Planalto Santareno), in the western of Pará state, Brazil. The method involves filtration and direct injection in the HPLC-FL for AMPA analysis, or previous concentration (10×) by lyophilization for glufosinate and glyphosate analysis. Analytes were oxidized and complexed with o-phthalaldehyde and 2-mercaptoethanol in a post-column reaction before fluorescence detection. LOQs for AMPA, glyphosate and glufosinate were established at 0.5, 0.2 and 0.3 µg L-1, respectively. A total of 58 samples were collected. Glyphosate and glufosinate were not detected in any of the 30 surface water samples collected in 2015 (

The Autism-Associated Gene Scn2a Contributes to Dendritic Excitability and Synaptic Function in the Prefrontal Cortex.

Autism spectrum disorder (ASD) is strongly associated with de novo gene mutations. One of the most commonly affected genes is SCN2A. ASD-associated SCN2A mutations impair the encoded protein NaV1.2, a sodium channel important for action potential initiation and propagation in developing excitatory cortical neurons. The link between an axonal sodium channel and ASD, a disorder typically attributed to synaptic or transcriptional dysfunction, is unclear. Here we show that NaV1.2 is unexpectedly critical for dendritic excitability and synaptic function in mature pyramidal neurons in addition to regulating early developmental axonal excitability. NaV1.2 loss reduced action potential backpropagation into dendrites, impairing synaptic plasticity and synaptic strength, even when NaV1.2 expression was disrupted in a cell-autonomous fashion late in development. These results reveal a novel dendritic function for NaV1.2, providing insight into cellular mechanisms probably underlying circuit and behavioral dysfunction in ASD.

Dynamics of glyphosate and AMPA in the soil surface layer of glyphosate-resistant crop cultivations in the loess Pampas of Argentina.

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 m2) 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 DT90 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 DT90 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.

Monitoring of glyphosate and AMPA in soil samples from two olive cultivation areas in Greece: aspects related to spray operators activities.

The persistence of glyphosate and its primary metabolite AMPA (aminomethylphosphonic acid) was monitored in two areas in Southern Greece (Peza, Crete and Chora Trifilias, Peloponnese) with a known history of glyphosate use, and the levels of residues were linked to spray operators' activities in the respective areas. A total of 170 samples were collected and analysed from both areas during a 3-year monitoring study. A new method (Impact Assessment Procedure - IAP) designed to assess potential impacts to the environment caused by growers' activities, was utilised in the explanation of the results. The level of residues was compared to the predicted environmental concentrations in soil. The ratio of the measured concentrations to the predicted environmental concentrations (MCs/PECs) was > 1 in Chora the first 2 years of sampling and < 1 in the third year, whilst the MCs/PECs ratio was < 1 in Peza, throughout the whole monitoring period. The compliance to the instructions for best handling practices, which operators received during the monitoring period, was reflected in the amount of residues and the MCs/PECs ratio in the second and especially the third sampling year. Differences in the level of residues between areas as well as sampling sites of the same area were identified. AMPA persisted longer than the parent compound glyphosate in both areas.

Spatial glyphosate and AMPA redistribution on the soil surface driven by sediment transport processes - A flume experiment.

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.