Distribution of pesticides and some of their transformation products in a small lentic waterbody: Fish, water, and sediment contamination in an agricultural watershed.

More than 20 years after the Water Framework Directive was adopted, there are still major gaps in the sanitary status of small rivers and waterbodies at the head of basins. These small streams supply water to a large number of wetlands that support a rich biodiversity. Many of these waterbodies are fishponds whose production is destined for human consumption or for the restocking of other aquatic environments. However, these ecosystems are exposed to contaminants, including pesticides and their transformation products. This work aims to provide information on the distribution, diversity, and concentrations of agricultural contaminants in abiotic and biotic compartments from a fishpond located at the head of watersheds. A total of 20 pesticides and 20 transformation products were analyzed by HPLC-ESI-MS/MS in water and sediment sampled monthly throughout a fish production cycle, and in three fish species at the beginning and end of the cycle. The highest mean concentrations were found for metazachlor-OXA (519.48 ± 56.52 ng.L-1) in water and benzamide (4.23 ± 0.17 ng g-1 dry wt.) in sediment. Up to 20 contaminants were detected per water sample and 26 per sediment sample. The transformation products of atrazine (banned in Europe since 2003 but still widely used in other parts of the world), flufenacet, imidacloprid (banned in France since 2018), metazachlor, and metolachlor were more concentrated than their parent compounds. Fewer contaminants were detected in fish and principally prosulfocarb accumulated in organisms during the cycle. Our work brings innovative data on the contamination of small waterbodies located at the head of a basin. The transformation products with the highest frequency of occurrence and concentrations should be prioritized for further environmental monitoring studies, and specific toxicity thresholds should be defined. Few contaminants were found in fish, but the results challenge the widely use of prosulfocarb.

Miniaturization of an extraction protocol for the monitoring of pesticides and polar transformation products in biotic matrices.

Monitoring pesticides in the environment requires the use of sensitive analytical methods. However, existing methods are generally not suitable for analyzing small organisms, as they require large matrix masses. This study explores the development of a miniaturized extraction protocol for the monitoring of small organisms, based on only 30 mg of matrix. The miniaturized sample preparation was developed using fish and macroinvertebrate matrices. It allowed the characterization of 41 pesticides and transformation products (log P from -1.9 to 4.8) in small samples with LC-MS/MS, based on European guidelines (European Commission DG-SANTE, 2019). Quantification limits ranged from 3 to 460 ng g-1 dry weight (dw) for fish and from 0.1 to 356 ng g-1 dw for invertebrates, with most below 60 ng g-1 dw. Extraction rates ranged from 70% to 120% for 35 molecules in fish. Recoveries ranged from 70% to 120% for 37 molecules in macroinvertebrates. Inter-day precision was below 30% for 32 molecules at quantification limits. The method was successfully applied to 17 fish and 19 macroinvertebrates collected from two ponds of the French region of Dombes in November and May 2018, respectively. Both sample matrices were nearly always contaminated with benzamide, imidacloprid-desnitro, and prosulfocarb at respective concentrations of 42-237, 3, and 30-165 ng g-1 dw in fish, and 62-438, 2-6, and 15-29 ng g-1 dw in macroinvertebrates. Results show that this method is an effective tool for characterizing polar pesticides in small biotic samples.

Development of a simple multiresidue extraction method for the quantification of a wide polarity range list of pesticides and transformation products in eggs by liquid chromatography and tandem mass spectrometry.

Waterfowl populations have been decreasing in Europe for the last years and pollution appears to be one of the main factors. This study was conducted to develop a single sensitive and robust analytical method for the monitoring of 2 fungicides, 15 herbicides, 3 insecticides and 24 transformation products in wild bird eggs. One of the major challenges addressed was the characterization of chemicals with large logP range (from -1.9 to 4.8). A total of 11 different extraction parameters were tested in triplicate to optimize the extraction protocol, on generic parameters, buffer addition and use of clean-up steps. Quantification was based on matrix-match approach with hen eggs as reference matrix (34 analytes with r²>0.99). Particular attention was payed to matrix effects (-28% on average), quantification limits (0.5 to 25 ng.g-1 dry mass / 0.2 to 7.5 ng.g-1 fresh mass) and extraction yields (46 to 87% with 25 analytes up to 70%) to ensure the relevance of the method and its compatibility with ultra-trace analysis. It led to a simple solid/liquid low temperature partitioning extraction method followed by LC-MS/MS. Analysis of 29 field samples from 3 waterfowl species revealed that eggs were slightly contaminated with pesticides as only one egg presented a contamination (terbutryn, herbicide, 0.7 ng.g-1) and confirmed the relevance of the method.