Ontario Ministry of the Environment, Conservation and Parks, Toronto, ON, Canada.
Laboratory Services Division, University of Guelph, Guelph, ON, Canada.
Chemosphere. 2022 May;294:133769. doi: 10.1016/j.chemosphere.2022.133769. Epub 2022 Jan 28.
Aquatic communities can be exposed to pesticides transported from land. Characterizing this exposure is key to predicting potential toxic effects. In this study, samples of streamwater from 21 sites were used to characterize pesticide exposure to aquatic communities. Sites were in agricultural areas of southwestern Ontario, Canada and were sampled monthly from 2012 to 2019 from April to November. Samples were analyzed for a suite of hundreds of pesticides and pesticide degradation products and other water quality indicators (e.g., nutrients). Frequently detected pesticides included herbicides (2,4-D; bentazon; MCPP; metolachlor) and neonicotinoid insecticides (NNIs) (clothianidin; thiamethoxam) which were detected in >50% of samples collected between 2015 and 2019. Non-metric multidimensional scaling (NMDS) was used to explore connections between pesticide concentrations and upstream land use and crop type. Detectable concentrations of the NNI clothianidin and many herbicides were related to corn, soybean, and grain/cereal crops while concentrations of the NNI imidacloprid, insecticide flonicamid, and fungicide boscalid were related to greenhouse/nursery land use. Potential toxicity to aquatic communities was assessed by comparing pesticide concentrations to Pesticide Toxicity Index (PTI) values. Few samples exceeded levels where acute (1% of samples) or chronic toxicity (10.5%) would be expected. The diamide insecticide chlorantraniliprole was detected in several streamwater samples at levels that may cause toxicity to aquatic invertebrates, highlighting the need for continued toxicity research into this pesticide class. The number of pesticides detected was positively correlated with nutrient and total suspended solids levels, underscoring the multiple stressors aquatic communities are exposed to in these habitats.
水生群落可能会接触到从陆地运输来的农药。对这种暴露进行特征描述是预测潜在毒性影响的关键。在这项研究中，利用 21 个地点的溪流水样来描述水生群落的农药暴露情况。这些地点位于加拿大安大略省西南部的农业区，从 2012 年到 2019 年，每月从 4 月到 11 月进行采样。对数百种农药和农药降解产物以及其他水质指标（如营养物质）进行了分析。经常检测到的农药包括除草剂（2,4-D；bentazon；MCPP；metolachlor）和新烟碱类杀虫剂（NNIs）（噻虫嗪；噻虫胺），这些农药在 2015 年至 2019 年期间采集的 50%以上的样本中均有检出。非度量多维尺度分析（NMDS）用于探索农药浓度与上游土地利用和作物类型之间的关系。可检出的 NNI 噻虫嗪和许多除草剂的浓度与玉米、大豆和谷物/谷物作物有关，而 NNI 吡虫啉、杀虫剂氟虫腈和杀菌剂肟菌酯的浓度则与温室/苗圃地有关。通过将农药浓度与农药毒性指数（PTI）值进行比较，评估对水生群落的潜在毒性。只有少数样本超过了预期会出现急性毒性（1%的样本）或慢性毒性（10.5%）的水平。几种溪流水样中检测到了联苯菊酯这种二酰胺类杀虫剂，其浓度可能对水生无脊椎动物产生毒性，这突出表明需要对这类农药进行持续的毒性研究。检出的农药数量与营养物质和总悬浮固体水平呈正相关，这突显了水生群落在这些栖息地中面临的多种胁迫。
