U.S. Geological Survey , 3215 Marine Street, Boulder, Colorado 80303, United States.
Environ Sci Technol. 2013 Mar 5;47(5):2177-88. doi: 10.1021/es303720g. Epub 2013 Feb 11.
Natural and synthetic organic contaminants in municipal wastewater treatment plant (WWTP) effluents can cause ecosystem impacts, raising concerns about their persistence in receiving streams. In this study, Lagrangian sampling, in which the same approximate parcel of water is tracked as it moves downstream, was conducted at Boulder Creek, Colorado and Fourmile Creek, Iowa to determine in-stream transport and attenuation of organic contaminants discharged from two secondary WWTPs. Similar stream reaches were evaluated, and samples were collected at multiple sites during summer and spring hydrologic conditions. Travel times to the most downstream (7.4 km) site in Boulder Creek were 6.2 h during the summer and 9.3 h during the spring, and to the Fourmile Creek 8.4 km downstream site times were 18 and 8.8 h, respectively. Discharge was measured at each site, and integrated composite samples were collected and analyzed for >200 organic contaminants including metal complexing agents, nonionic surfactant degradates, personal care products, pharmaceuticals, steroidal hormones, and pesticides. The highest concentration (>100 μg L(-1)) compounds detected in both WWTP effluents were ethylenediaminetetraacetic acid and 4-nonylphenolethoxycarboxylate oligomers, both of which persisted for at least 7 km downstream from the WWTPs. Concentrations of pharmaceuticals were lower (<1 μg L(-1)), and several compounds, including carbamazepine and sulfamethoxazole, were detected throughout the study reaches. After accounting for in-stream dilution, a complex mixture of contaminants showed little attenuation and was persistent in the receiving streams at concentrations with potential ecosystem implications.
市政污水处理厂（WWTP）废水中的天然和合成有机污染物会对生态系统造成影响，这引起了人们对它们在受纳溪流中持久性的关注。在这项研究中，采用拉格朗日采样法（Lagrangian sampling），即跟踪同一近似水样在下游移动的过程，对科罗拉多州博尔德溪（Boulder Creek）和爱荷华州四英里溪（Fourmile Creek）进行了采样，以确定从两个二级 WWTP 排放的有机污染物在溪流中的迁移和衰减。对相似的溪流段进行了评估，并在夏季和春季水文条件下的多个地点采集了样本。在夏季，博尔德溪最下游（7.4 公里）站点的水流到达时间为 6.2 小时，而在春季则为 9.3 小时；而在四英里溪下游 8.4 公里的站点，水流到达时间分别为 18 小时和 8.8 小时。在每个站点都测量了流量，并采集了综合复合样本，用于分析 >200 种有机污染物，包括金属络合剂、非离子表面活性剂降解产物、个人护理产品、药物、甾体激素和农药。在两个 WWTP 废水中都检测到浓度最高（>100 μg L(-1))的化合物是乙二胺四乙酸和 4-壬基酚乙氧基羧酸低聚物，它们都至少在 WWTP 下游 7 公里处存在。药物的浓度较低（<1 μg L(-1))，在整个研究过程中都检测到了几种化合物，包括卡马西平和磺胺甲恶唑。在考虑了溪流中的稀释作用后，含有多种污染物的复杂混合物在受纳溪流中几乎没有衰减，并且以可能对生态系统产生影响的浓度持续存在。
