Water Sciences Laboratory, 202 Water Sciences Laboratory, University of Nebraska, Lincoln, NE, 68583, USA.
Department of Civil Engineering, SRM Institute of Science and Technology, Kancheepuram District, Tamil Nadu, 603203, India.
Water Res. 2020 Oct 1;184:116141. doi: 10.1016/j.watres.2020.116141. Epub 2020 Jul 7.
The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river's importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 μg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p'-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 μg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column.
锡尔河是中亚的两条主要河流之一，为咸海提供了关键的淡水。尽管这条河具有重要性并且在农业上历史悠久，但很少有研究对农药残留对水生生物的潜在影响进行现代评估。本研究的主要目标是确定哈萨克斯坦（KZ）锡尔河下游乌兹别克斯坦农业密集型流域中底泥和水中现代和遗留农药的季节性变化。在 2015 年 6 月，使用五点远程采样站的抓斗采样和被动采样器为生态毒理学评估提供基线。结果与农业生长季节期间和之后采集的样本进行了比较。在 6 月使用极性有机化学综合采样器（POCIS）并对当前使用农药的时间加权平均浓度进行校准。在从河流中采集的抓斗样本中测量的遗留氯代农药中，林丹（γ-六氯环己烷）最常被检出，浓度最高的时期是 6 月。对于所有采样事件，在水样中检测到的林丹（γ-六氯环己烷）残留量为 0.014 至 0.24μg/L，是全球河流中报告的最高浓度之一。γ-六氯环己烷、p,p'-滴滴伊和狄氏剂的浓度在 10 月最高，当时狄氏剂的浓度接近 0.4μg/L。遗留农药的来源可能是上游非法使用，也可能是冰川融水先前受到大气污染的证据。这些残留物的慢性暴露可能会对底泥和水柱中的低等生物造成生态风险。
