Collaborative Research: Establishing the role of photodegradation in the fate of organic contaminants in aquatic systems

农药和药物等合成有机化合物可通过点源(如废水处理厂的流出物)和非点源(如城市和农业流域的径流)进入地表水系统(如湖泊和河流)。这些有机污染物会对人类和生态系统健康产生不利影响。了解阳光对水生系统中合成有机污染物的降解速度，对于预测和管理它们的健康风险非常重要。然而，使用模拟阳光的实验室实验不能直接转化为环境条件，也大大高估了阳光与包括湖泊和河流在内的地表水系统中合成有机化学品的反应速度。因此，这些化学物质在地表水中的寿命可能比目前预测的更长。该项目的总体目标是促进对地表水系统中合成有机污染物的阳光诱导光化学降解的基本理解。为了推进这一目标，首席调查员(PI)将在实验室和户外研究大约50种杀虫剂、药物和工业化学品，并将利用这些信息对河流和湖泊中阳光驱动的降解反应做出准确预测。这项研究的成功完成将通过产生关于水生系统中合成有机污染物在阳光驱动下的光化学反应的程度和速率的新数据和基本知识，使社会受益。这些新的数据和知识将对评估湖泊和河流中潜在有毒有机化合物的命运和寿命至关重要。通过学生教育和培训将获得更多好处，包括指导威斯康星大学麦迪逊分校的一名研究生和圣托马斯大学的两名本科生，圣托马斯大学是一所以本科为主的院校。阳光介导的光降解是农药和药品等合成有机化合物(SOC)在水生系统中最重要的非生物转化过程之一。该项目的一个主要目标是检验一种假设，即由于实验室光源和环境条件之间的差异，实验室规模的实验高估了湖泊和河流中有机碳的光解率许多数量级。为了验证这一假设，首席调查员(PI)建议评估大约50种农药、药物和工业化学品在相关水生系统中的直接光解，目的是建立一个第一原理动力学模型，将实验室直接光解速率与各种环境条件联系起来。该模型将通过室外中尺度实验来验证，这些实验量化了日变化、水深、云量和季节性对水生系统中SOC直接光解速率的影响。最后，PI建议结合实验室和室外实验，并建立模型来研究选定SOC在溶解有机物(DOM)存在下的间接光解速率。DOM是地表水系统中的一种天然光敏剂，可以吸收光线产生光化学产生的活性中间体，如羟基自由基和单线态氧。该项目的成功完成具有潜在的变革性影响，因为它将实验室测量的速率与各种有机碳在湖泊/河流中的预期光降解速率联系起来。为了实现该项目的教育和培训目标，PIS建议利用威斯康星大学麦迪逊分校和圣托马斯大学的现有项目，招募和指导本科生，包括那些来自代表性不足群体的本科生，以参与该项目。此外，PIS计划1)将研究成果纳入威斯康星大学麦迪逊分校土木工程和环境工程系现有的本科生和研究生课程，2)开发一个网站，其中将包括一个数据库，其中包含该项目所有经过验证的结果。这些结果将传播给水资源管理者、相关利益相关者和公众。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Synthetic organic compounds such as pesticides and pharmaceuticals can enter surface water systems (e.g., lakes and rivers) through point sources (e.g., effluents from wastewater treatment plants) and non-point sources (e.g., runoff from urban and agricultural watersheds). These organic pollutants can adversely affect both human and ecosystem health. Understanding how quickly sunlight reacts to degrade synthetic organic pollutants in aquatic systems is important for predicting and managing their health risks. However, laboratory experiments using simulated sunlight cannot be directly translated to environmental conditions and greatly overestimate how quickly sunlight reacts with synthetic organic chemicals in surface water systems including lakes and rivers. As a result, these chemicals may have longer lifetimes in surface waters than currently predicted. The overarching goal of this project is to advance the fundamental understanding of sunlight-induced photochemical degradations of synthetic organic pollutants in surface water systems. To advance this goal, the Principal Investigators (PIs) will study approximately 50 pesticides, pharmaceuticals, and industrial chemicals in the laboratory and outdoors and will use this information to make accurate predictions about sunlight-driven degradation reactions in rivers and lakes. The successful completion of this research will benefit society through the generation of new data and fundamental knowledge about the extents and rates of sunlight-driven photochemical reactions of synthetic organic pollutants in aquatic systems. This new data and knowledge will be critical for evaluating the fate and lifetime of potentially toxic organic chemicals in lakes and rivers. Additional benefits will be achieved through student education and training including the mentoring of one graduate student at the University of Wisconsin-Madison and two undergraduate students at the University of St. Thomas, a predominantly undergraduate institution.Sunlight-mediated photodegradation is among the most important abiotic transformation processes in aquatic systems for synthetic organic compounds (SOCs) such as pesticides and pharmaceuticals. A major goal of this project is to test the hypothesis that laboratory-scale experiments overpredict the photolysis rates of SOCs in lakes and rivers by many orders of magnitude due to discrepancies between laboratory light sources and environmental conditions. To test this hypothesis, the Principal Investigators (PIs) propose to evaluate the direct photolysis of approximately 50 pesticides, pharmaceuticals, and industrial chemicals in relevant aquatic systems with the goal of developing a first principles kinetic model to relate laboratory direct photolysis rates to a variety of environmental conditions. The model will be validated using outdoor mid-scale experiments that quantify the impacts of diurnal variability, water depth, cloud cover, and seasonality on the rates of direct photolysis of SOCs in aquatic systems. Finally, the PIs propose to couple laboratory and outdoor experiments, and modeling to investigate the indirect photolysis rates of selected SOCs in the presence of dissolved organic matter (DOM), a natural photosensitizer in surface water systems that absorbs light to generate photochemically produced reactive intermediates such as hydroxyl radicals and singlet oxygen species. The successful completion of this project has the potential for transformative impact by linking laboratory-measured rates with expected photodegradation rates in lakes/rivers for a wide range of SOCs. To implement the educational and training goals of this project, the PIs propose to leverage existing programs at the University of Wisconsin (UW)-Madison and the University of St. Thomas to recruit and mentor undergraduate students, including those from underrepresented groups, to work on this project. In addition, the PIs plans to 1) integrate the research findings into existing undergraduate and graduate courses in the Department of Civil and Environmental Engineering at the UW-Madison and 2) develop a website that will include a database containing all the validated results of the project. These results will be disseminated to water resource managers, relevant stakeholders, and the public.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.