DataSheet2_Impact of wastewater reuse on contaminants of emerging concern in an effluent-dominated river.ZIP

Contaminants of emerging concern such as pharmaceuticals, personal care products, per- and polyfluoroalkyl substances, and plasticizers, are ubiquitous in effluent-dominated rivers and have potential adverse effects on humans and aquatic life. Demands on water supply have prompted conservation and water reuse measures, impacting the discharge in these rivers, yet the effects of these management decisions on water quality are largely intuited and not quantified. This research examines how changes in water reuse practices will impact concentrations of contaminants of emerging concern, specifically carbamazepine, diclofenac, galaxolide, gemfibrozil, 4-nonylphenol, and perfluorooctane sulfonic acid (PFOS), in the effluent-dominated Los Angeles River (Los Angeles County, California). A water quality module was added to a calibrated hydrologic model of the system and parametrized with observed water quality monitoring data in EPA SWMM. Results indicate that water reuse (i.e., reduced effluent flow) will consistently improve in-stream water quality for all compounds studied except PFOS. However, the improvements are often not substantial enough to mitigate high concentrations directly downstream of treated effluent discharge points. Concentrations of these pharmaceuticals are substantially reduced through attenuation as dilution and degradation occur downstream, though the rate of this attenuation is variable and based on the contaminant. In contrast, concentrations of PFOS increase under some wastewater reuse scenarios and decrease under others but remain below the recommended environmental screening levels. Our work also highlights that management decisions regarding water quantity should integrate water quality modeling to help identify priority monitoring locations and constituents.

新兴关注污染物（Contaminants of Emerging Concern）包括药品、个人护理用品、全氟和多氟烷基物质以及增塑剂，在以废水为主导的河流中普遍存在，对人类与水生生物具有潜在不利影响。供水需求推动了节水与水回用措施的实施，进而影响了这类河流的径流排放，但此类管理决策对水质的影响大多仅为主观推测，尚未得到量化。本研究以加利福尼亚州洛杉矶县境内以废水为主导的洛杉矶河为研究对象，探究水回用模式的变化将如何影响其中的新兴关注污染物浓度，具体包括卡马西平、双氯芬酸、佳乐麝香、吉非贝齐、4-壬基酚以及全氟辛烷磺酸（PFOS）。本研究在已率定的流域水文模型中增设了水质模块，并基于美国环境保护署暴雨管理模型（EPA SWMM）中的实测水质监测数据对该模块进行参数化设置。研究结果显示，除全氟辛烷磺酸外，水回用（即减少废水排放量）可持续改善研究涉及的所有污染物对应的河流水质。但此类水质改善幅度通常不足以缓解污水处理厂排放口下游直接区域的高浓度污染问题。随着下游发生稀释与降解作用，此类药品的浓度会通过衰减过程大幅降低，不过衰减速率因污染物种类而异。与之相反，全氟辛烷磺酸的浓度在部分废水回用场景下会升高，在其他场景下则会降低，但始终低于推荐的环境筛选阈值。本研究同时强调，针对水量的管理决策应纳入水质建模环节，以辅助确定优先监测点位与监测污染物清单。