Dept. of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel; Faculty of Marine Sciences, Ruppin Academic Center, Mikhmoret, 402970, Israel.
The Soil Erosion Research Station, Soil Conservation and Drainage Division, Ministry of Agriculture and Rural Development, Bet Dagan, 50250, Israel.
Environ Pollut. 2020 Oct;265(Pt B):114941. doi: 10.1016/j.envpol.2020.114941. Epub 2020 Jun 5.
Pesticides are potentially toxic to aquatic systems, even at low concentration, depending on their individual ecotoxicological properties and their mixture composition. Thus, to evaluate possible ecological stress due to pesticide load, a thorough assessment of the potential toxicity of pesticide mixtures is required. Here we report water discharge and quality data of an eastern Mediterranean micro-estuary (Alexander stream), targeting the temporal distribution of a pesticide mixture. Over 150 water samples were collected during 2 hydrological years representing base-flow and flood conditions. On average, each water sample contained 34 and 45 different pesticides with peak concentrations of 1.4 μg L of Imidacloprid and 55 μg L of Diuron during base-flow and flood events, respectively. Pesticide mixtures were potentially toxic to benthic invertebrates and algae during flood events, surpassing the toxicity benchmark with medians of 110% and 155%, respectively. The herbicide Diuron and the insecticide Imidacloprid were the main pesticides responsible for the high potential toxicity during flood events. The falling limb of the flood hydrographs was found to inflict the highest stress on the estuarine environment due to elevated toxicity combined with prolonged residence time of the water. Examination of the potential chronic toxicity of single compounds showed continuous stress for plants, algae, amphibians, crustaceans, insects and fish from nine pesticides. Our data show that the ecosystem of the Alexander micro-estuary is under a continuous chronic stress with acute peaks in potential toxicity during flood events and the period that follows them. We propose that analyzing a small set of flood-tail samples is needed for the evaluation of small estuarine ecosystems risk during the rainy season. From a management perspective, we suggest better control of application practices for Diuron in the watershed to minimize the stress to the estuarine ecosystem.
农药即使在低浓度下也可能对水生系统造成毒性，具体取决于其各自的生态毒理学特性及其混合物成分。因此，为了评估由于农药负荷而产生的潜在生态胁迫，需要对农药混合物的潜在毒性进行全面评估。在这里，我们报告了一个地中海东部小河口（亚历山大河）的污水排放和水质数据，旨在针对农药混合物的时间分布进行评估。在两个水文年期间采集了超过 150 个水样，代表基础流量和洪水条件。平均而言，每个水样中含有 34 种和 45 种不同的农药，在基础流量和洪水事件中，分别达到了 1.4μg/L 的吡虫啉和 55μg/L 的敌草隆的峰值浓度。在洪水事件中，农药混合物对底栖无脊椎动物和藻类具有潜在毒性，分别超过毒性基准的 110%和 155%。在洪水事件中，除草剂敌草隆和杀虫剂吡虫啉是造成高潜在毒性的主要农药。洪水水文学的下降支被发现由于毒性升高和水的停留时间延长，对河口环境造成最大的压力。对单一化合物的潜在慢性毒性的检查表明，来自九种农药的植物、藻类、两栖动物、甲壳类动物、昆虫和鱼类持续受到压力。我们的数据表明，亚历山大小河口的生态系统处于持续的慢性压力之下，在洪水事件及其后续期间存在潜在毒性的急性峰值。我们提出，在雨季评估小河口生态系统的风险时，需要对洪水尾部的小样本进行分析。从管理的角度来看，我们建议在流域内更好地控制敌草隆的使用实践，以最大程度地减少对河口生态系统的压力。
