The Salinas Valley in Monterey County, California, USA, is a highly productive agricultural region. Irrigation runoff containing pesticides at concentrations toxic to aquatic organisms poses a threat to aquatic ecosystems within local watersheds. This study monitored the effectiveness of a constructed wetland treatment system with a granulated activated carbon (GAC) filter installation at reducing pesticide concentrations and associated toxicity to Ceriodaphnia dubia, Hyalella azteca, and Chironomus dilutus. The wetland was supplied with water pumped from an impaired agricultural and urban drainage. Across five monitoring trials, the integrated system’s average pesticide concentration reduction was 52%. The wetland channel and GAC filtration components individually provided significant treatment, and within each, pesticide solubility had a significant effect on changes in pesticide concentrations. The integrated treatment system also reduced nitrate by 61%, phosphate by 73%, and turbidity by 90%. Input water was significantly toxic to C. dubia and H. azteca in the first trial. Toxicity to C. dubia persisted throughout the system, whereas toxicity to H. azteca was removed by the channel, but there was residual toxicity post-GAC. The final trial had significant input toxicity to H. azteca and C. dilutus. The channel reduced toxicity to H. azteca and removed toxicity to C. dilutus. GAC filtration reduced H. azteca toxicity to an insignificant level. There was no input toxicity in the other three trials. The results demonstrate that a wetland treatment system coupled with GAC filtration can reduce pesticide concentrations, nutrients, suspended particles, and aquatic toxicity associated with agricultural runoff.

美国加利福尼亚州蒙特雷县的萨利纳斯河谷是一个高产的农业区。含有对水生生物有毒浓度的杀虫剂的灌溉径流对当地流域内的水生生态系统构成威胁。本研究监测了带有颗粒状活性炭 (GAC) 过滤装置的人工湿地处理系统在降低农药浓度和对Ceriodaphnia dubia、Hyalella azteca和Chironomus dilutus的相关毒性方面的有效性. 湿地的供水来自受损的农业和城市排水系统。在五次监测试验中，综合系统的农药浓度平均降低了 52%。湿地通道和 GAC 过滤组件分别提供了显着的处理，在每个组件中，农药溶解度对农药浓度的变化都有显着影响。集成处理系统还将硝酸盐降低了 61%，磷酸盐降低了 73%，浊度降低了 90%。在第一次试验中，输入水对C. dubia和H. azteca具有显着毒性。对C. dubia的毒性在整个系统中持续存在，而对H. azteca的毒性被通道去除，但在 GAC 后仍有残留毒性。最终试验对H. azteca和C. dilutus具有显着的输入毒性。该通道降低了对H. azteca的毒性并消除了对C. dilutus的毒性。GAC 过滤将H. azteca毒性降低到微不足道的水平。在其他三个试验中没有输入毒性。结果表明，与 GAC 过滤相结合的湿地处理系统可以降低与农业径流相关的农药浓度、营养物质、悬浮颗粒和水生毒性。