Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, Universitätstrasse 16, ETH Zürich, 8092 Zürich, Switzerland.
Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
Water Res. 2024 Dec 1;267:122412. doi: 10.1016/j.watres.2024.122412. Epub 2024 Sep 14.
Generally, karst aquifers and springs are highly susceptible to contamination due to the high permeability and, therefore, groundwater flow velocities. The often thin soil cover, accompanied by dolines, can lead to fast infiltration of precipitation water loaded with mobilized contaminants such as pesticides and their transformation products. To date, continuous, temporally highly resolved in-situ monitoring to decipher concentration dynamics for a broad range of pesticides is missing. Therefore, a transportable HPLC-HRMS/MS system (MSfield) was positioned at two karst study sites in the Swiss Jura. Water samples were collected and analyzed for pesticides and their transformation products in-situ every 20 min for 6 weeks in 2021 and 8 weeks in 2022. During the spraying season in 2021, six rain events at site 1 and three at site 2 in 2022 were captured. Concurrently, the water quality parameters electrical conductivity, pH, nitrate, turbidity, and water level, were monitored continuously at high temporal resolution. Further, bacterial cell counts were monitored via online flow cytometry. In 2021, several pesticides and pesticide transformation products were detected in peak concentrations after rain events, of which metamitron showed the highest concentration of up to 1000 ng/L. In one rain event, the Swiss federal and EU drinking water limit of 100 ng/L was exceeded for up to 38 h. Compared with highly frequent MSfield samples collected every 20 min, 42-hours composite samples severely underestimated peak concentrations for all compounds, especially for labile ones. Therefore, it was demonstrated that exceedences of the regulatory limit would have been missed if just composite sampling would have been conducted. Peak concentrations of pesticides coincided with peaks in nitrate concentration and bacterial cell counts following rain events. The correlation analysis showed strong correlations between the three analyzed contaminants (pesticides, nitrate and bacteria), and the proxy parameters electrical conductivity, and pH. The investigation of a second spring revealed similar dynamics indicating that these can be expected in other karst aquifers as well.
一般来说，由于高渗透性和因此的地下水流速，岩溶含水层和泉水极易受到污染。通常较薄的土壤覆盖层伴随着陷坑，会导致加载有移动污染物（如农药及其转化产物）的降水快速渗透。迄今为止，对于广泛的农药，仍缺乏连续的、时间分辨率高的原位监测，以解析其浓度动态。因此，在瑞士汝拉山区的两个岩溶研究点部署了一个可移动的 HPLC-HRMS/MS 系统（MSfield）。在 2021 年的 6 周和 2022 年的 8 周内，每隔 20 分钟采集并原位分析水样中的农药及其转化产物。在 2021 年的喷洒季节，捕获了 1 号点的 6 次降雨事件和 2 号点的 3 次降雨事件。同时，连续高时间分辨率地监测水质参数电导率、pH 值、硝酸盐、浊度和水位。此外，通过在线流式细胞术监测细菌细胞计数。2021 年，在雨后的峰值浓度中检测到了几种农药和农药转化产物，其中甲拌磷的浓度最高，达到了 1000ng/L。在一次降雨事件中，瑞士联邦和欧盟饮用水限值为 100ng/L 的标准持续了长达 38 小时。与每隔 20 分钟采集的高频率 MSfield 样本相比，42 小时的复合样本严重低估了所有化合物的峰值浓度，尤其是易变化合物。因此，结果表明，如果仅进行复合采样，将错过监管限值的超标。雨后，农药的峰值浓度与硝酸盐浓度和细菌细胞计数的峰值同时出现。相关分析表明，三种分析污染物（农药、硝酸盐和细菌）与电导率和 pH 值等代理参数之间存在很强的相关性。对第二个泉的调查显示出类似的动态，表明这些动态也可以在其他岩溶含水层中出现。
