Pennsylvania Cooperative Fish & Wildlife Research Unit, Pennsylvania State University, University Park, PA 16802, United States.
U.S. Geological Survey, Earth System Processes Division, University of Connecticut Storrs Mansfield, CT 06269, United States.
Sci Total Environ. 2021 Feb 10;755(Pt 1):142873. doi: 10.1016/j.scitotenv.2020.142873. Epub 2020 Oct 9.
Groundwater discharge zones in streams are important habitats for aquatic organisms. The use of discharge zones for thermal refuge and spawning by fish and other biota renders them susceptible to potential focused discharge of groundwater contamination. Currently, there is a paucity of information about discharge zones as a potential exposure pathway of chemicals to stream ecosystems. Using thermal mapping technologies to locate groundwater discharges, shallow groundwater and surface water from three rivers in the Chesapeake Bay Watershed, USA were analyzed for phytoestrogens, pesticides and their degradates, steroid hormones, sterols and bisphenol A. A Bayesian censored regression model was used to compare groundwater and surface water chemical concentrations. The most frequently detected chemicals in both ground and surface water were the phytoestrogens genistein (79%) and formononetin (55%), the herbicides metolachlor (50%) and atrazine (74%), and the sterol cholesterol (88%). There was evidence suggesting groundwater discharge zones could be a unique exposure pathway of chemicals to surface water systems, in our case, metolachlor sulfonic acid (posterior mean concentration = 150 ng/L in groundwater and 4.6 ng/L in surface water). Our study also demonstrated heterogeneity of chemical concentration in groundwater discharge zones within a stream for the phytoestrogen formononetin, the herbicides metolachlor and atrazine, and cholesterol. Results support the hypothesis that discharge zones are an important source of exposure of phytoestrogens and herbicides to aquatic organisms. To manage critical resources within the Chesapeake Bay Watershed, more work is needed to characterize exposure in discharge zones more broadly across time and space.
河流中的地下水排泄区是水生生物的重要栖息地。鱼类和其他生物利用排泄区作为热避难所和产卵地，这使得它们容易受到地下水污染的潜在集中排放的影响。目前，关于排泄区作为化学物质进入溪流生态系统的潜在暴露途径的信息很少。本研究使用热成像技术定位地下水排泄区，对来自美国切萨皮克湾流域的三条河流的浅层地下水和地表水进行了植物雌激素、农药及其降解物、甾体激素、固醇和双酚 A 的分析。采用贝叶斯删失回归模型比较了地下水和地表水的化学浓度。在地下水和地表水中均检测到的最常见化学物质是植物雌激素染料木黄酮（79%）和芒柄花素（55%）、除草剂甲草胺（50%）和莠去津（74%）以及固醇胆固醇（88%）。有证据表明，地下水排泄区可能是化学物质进入地表水系统的独特暴露途径，就我们的情况而言，是甲草胺磺酸（地下水的后验平均浓度为 150ng/L，地表水为 4.6ng/L）。我们的研究还表明，在河流中的地下水排泄区，植物雌激素芒柄花素、除草剂甲草胺和莠去津以及胆固醇的化学浓度存在异质性。研究结果支持这样一种假设，即排泄区是植物雌激素和除草剂暴露于水生生物的重要来源。为了管理切萨皮克湾流域的关键资源，需要做更多的工作来更广泛地描述在时间和空间上的排泄区的暴露情况。
