Resolving uncertainties in sewage subsidies to urban aquatic ecosystems using continuous sensing and stable isotopes

城市溪流和河流中的污水对人类和环境健康构成重大风险：病原体增加了处理饮用水的成本，使娱乐活动变得危险，而径流和废物中的过量营养物质可能导致藻类大量繁殖，从而破坏水生生态系统，限制娱乐用途。该项目涉及城市河流和城市水基础设施系统之间的相互作用。污水管靠重力流动，因此经常被故意安装在河道中。随着管道老化和泄漏，河流-下水道相互作用和污染的可能性更大。目前，美国有45个主要城市将国内下水道和雨水排放管合并到同一个管道系统中。当下雨时，多余的废水与雨水结合，并可以通过联合下水道溢流直接流入溪流和河流。尽管这一问题普遍存在，但巴尔的摩和凤凰城的两个国家城市河流研究中心都没有包括合并下水道溢流的流域。在这个项目中，将在宾夕法尼亚州匹兹堡的一条城市河流中建立一套流中传感器。 传感器将以15分钟的间隔收集水质测量值，并以精细的时间尺度提供前所未有的洞察力，以了解污水泄漏和溢流如何影响城市河流水质。该项目将通过加深对重大健康风险的理解，加强学术界与当地流域协会之间的关系，以及教育公众了解水质，公共卫生和持续监测工作，使社会广泛受益。 由于水文变化和人为养分补贴，仍然迫切需要了解城市基础设施系统对河流养分负荷的影响。本研究探讨了难以捉摸的连接集水管基础设施和生态影响城市水生生态系统通过测量精细解决硝酸盐浓度和其他水质参数的变化，评估污水补贴对流中总初级生产力的影响，并探讨在暴雨事件中硝酸盐动员和运输的变化。这将通过使用稳定同位素示踪剂（硝酸盐，水）和连续传感的不寻常组合来实现，以解开流域运输和城市系统中营养物质转化的复杂信号。 Nine Mile Run是宾夕法尼亚州匹兹堡市的一条城市河流，其源头被掩埋，共同定位的下水道基础设施和合并的下水道溢流将成为研究的重点。 一个水质监测站配备了紫外线硝酸盐分析仪和多参数水质探测仪，将在两年时间内测量高频水化学。现场传感器，沿着一个ISCO自动采样器，将捕捉和揭示日常变化的全部范围，以及风暴中期的变化，这些变化在以前的抓取采样中是不可见的。硝酸盐和水的来源，时间和交付的数据相结合，将允许更好地表征溶质流动路径，阐明何时以及如何发生废水-地下水-地表水相互作用，以及它们对流域运输，河流生产力和河流地球化学的影响。 该项目将通过加深对重大健康风险的理解，教育公众了解水质、公共卫生和持续监测工作，使社会广泛受益。该奖项还将扩大匹兹堡水研究、教育和推广合作实验室的持续努力，以加强匹兹堡大学研究人员与社区之间的合作，并继续建立以社区参与水研究为中心的研究生课程。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The presence of sewage in urban streams and rivers poses significant risks to human and environmental health: pathogens increase costs to treat drinking water and make recreation dangerous whereas excess nutrients from runoff and waste can cause algal blooms that can decimate aquatic ecosystems and limit recreational uses. This project addresses interactions between urban streams and urban water infrastructure systems. Sewage pipes flow by gravity, and thus are often deliberately installed in stream channels. As pipes age and leak, stream-sewer interactions and contamination are more likely. Currently, 45 major US cities have domestic sewer and storm drains combined into the same pipe system. When it rains, excess wastewater combines with stormwater, and can flow directly into streams and rivers through a combined sewer overflow. Despite the prevalence of this problem, neither of the two national centers of urban stream research in Baltimore and Phoenix include watersheds with combined sewer overflows. For this project, a nest of in-stream sensors will be established within an urban stream in Pittsburgh, PA. Sensors will collect water quality measurements at 15-minute intervals and give unprecedented insight as to how sewage leaks and overflows affect urban stream water quality at finely resolved time scales. This project will broadly benefit society by deepening understanding of a significant health risk, strengthening relationships between academia and local watershed associations, and educating the public about water quality, public health, and ongoing monitoring efforts. Due to altered hydrology and anthropogenic nutrient subsidies, there remains a critical need to understand the impacts of urban infrastructure systems on stream nutrient loads. This research investigates the elusive connection between catchment pipe infrastructure and ecological impacts in urban aquatic ecosystems by measuring finely-resolved changes in nitrate concentrations and other water quality parameters, evaluating the effects of sewage subsidies on in-stream gross primary productivity, and exploring changes in nitrate mobilization and transport during storm events. This will be accomplished using an unusual combination of stable isotope tracers (nitrate, water) and continuous sensing to disentangle the convoluted signals of watershed transport and transformation of nutrients in urban systems. Nine Mile Run, an urban stream in Pittsburgh, PA with buried headwaters, co-located sewer pipe infrastructure, and combined sewer overflows, will be the focus of the study. A water quality station featuring an ultraviolet nitrate analyzer and a multi-parameter water quality sonde will measure high frequency water chemistry over a two-year period. In-situ sensors, along with an ISCO autosampler, will capture and reveal the full range of daily variations, as well as mid-storm changes, that have not been visible with previous grab sampling. This combination of data on the sources, timing, and delivery of both nitrate and water will allow for better characterization of solute flow paths, elucidate when and how wastewater-groundwater-surface water interactions are occurring, and the effects they have on catchment transport, stream productivity, and stream biogeochemistry. This project will broadly benefit society by deepening understanding of a significant health risk and educating the public about water quality, public health, and ongoing monitoring efforts. It will also expand upon ongoing efforts by the Pittsburgh Collaboratory for Water Research, Education and Outreach to strengthen collaborations between University of Pittsburgh researchers with communities and to continue building a graduate program centered on community-engaged water research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.