Environmental change and rising DOC trends: Implications for public health

这个高度综合的多学科项目利用环境科学家、数学建模师、分析化学家、毒理学家和公共卫生科学家的技能，在区域范围内解决未来环境变化对土壤-水生态系统的影响所造成的健康脆弱性问题。它将讨论最近观察到的用于饮用水提取的水生生态系统中溶解有机碳（DOC）浓度上升的惊人趋势对健康的影响。在过去二十年中，这些水源的许多水源中的溶解有机碳（DOC）浓度增加了一倍以上，并继续上升（Freeman et al., 2001）。越来越多的证据表明，这一过程是由环境变化驱动的，例如酸性沉积的减少（Evans等人，2006年；Monteith等人，2007年），再加上气温上升、干旱频率增加和降雨季节性分布的变化。我们的目标是分析监测计划和其他研究的数据，以预测未来气候变化和空气污染对进入水库和滤水厂的水中DOC浓度的可能影响。进入滤水厂的DOC含量增加，对人体健康有重大影响。使用无机混凝剂的常规处理只能部分去除原水中的有机物；剩下的可能会与消毒剂发生反应。在给水加氯过程中，氯不仅与微生物发生反应，而且还与水中存在的大多数其他有机物质发生反应，要么溶解，要么悬浮。这会产生一系列被称为消毒副产物（DPBs）的有机化合物，包括一组被称为三卤甲烷（THMs）的化学物质，以及卤乙酸、卤硝基、卤醛和氯酚。我们将进行实验室实验，以测试我们所预测的未来DOC变化对水处理系统内产生这些化合物的可能影响。此外，来自工业、肥料施用和城市废水的空气污染物的各种其他化学污染物可能（通过吸附）与天然有机物结合，并与DOC一起被输送到水库和水处理厂。它们在处理系统中的命运，即它们是被去除还是留在溶液中，在很大程度上取决于污染物的类型、DOC的性质（或质量）、水溶液的化学性质（例如pH值和离子强度）以及处理过程的类型。我们会进行实验室实验，以确定这些污染物在进入水处理过程时与DOC结合的程度，以及在处理过程中可能发生的情况，例如污染物可能被去除或留在溶液中的程度。当暴露于化学污染物中时，生物体会以不同的方式和时间尺度作出反应。有些对生物体的影响是立竿见影的，而另一些影响可能会延迟，10年、20年或更长时间才会显现；例如，人类的癌症。我们将借鉴国家和国际（欧盟）政府机构现有的风险评估方法，评估环境变化情景下一系列污染物水平变化对人类健康的潜在影响。最后，我们将把我们的研究结果以决策支持系统（DSS）的形式汇集在一起，该系统将为水务行业、环境机构和其他利益相关者提供信息。DSS将提供在未来气候变化情景下DOC可能趋势的预测，以及预测的变化对更广泛的水质和人类健康的可能重要性。

This highly integrated multidisciplinary project engages the skills of environmental scientists, mathematical modellers, analytical chemists, toxicologists and public health scientists to address health vulnerability issues resulting from future environmental change impacts on soil-water ecosystems at a regional scale. It will address the health implications of a recently observed alarming trend for rising Dissolved Organic Carbon (DOC) concentrations in aquatic ecosystems used for potable water abstraction. Over the past two decades the concentration of dissolved organic carbon (DOC) in many source waters of these source waters has more than doubled and continues to rise (Freeman et al., 2001). There is increasing evidence to suggest that the process is being driven by environmental changes such as a decline in acid deposition (Evans et al., 2006; Monteith et al. 2007), combined with rising temperatures, increased frequency of drought and changes in the seasonal distribution of rainfall. We aim to analyse data from monitoring programmes and various other studies to allow us to predict the likely impact of future changes in climate and air pollution on DOC concentrations in water entering reservoirs and water treatment works. The increase in the level of DOC reaching water treatment works has major implications for human health. Organic matter in raw water is only partially removed by conventional treatment using inorganic coagulants; what remains may react with disinfectants. During chlorination of water supplies the chlorine reacts not only with the microorganisms but also with most of the other organic material present in the water, either dissolved or in suspension. This produces a range of organic compounds known as disinfection by-products (DPBs) including a group of chemicals called trihalomethanes (THMs), plus haloacetic acids, halonitriles, haloaldehydes and chlorophenols. We will carry out laboratory experiments to test the likely implications of the future changes in DOC we have predicted for the generation of these compounds within the water treatment system. Furthermore, a wide variety of other chemical contaminants, derived from air pollutants from industry, fertilizer application and urban waste water may bind (by sorption) to natural organic matter and be transported into reservoirs and water treatment works in association with DOC. Their fate within the treatment system, i.e. whether they are removed or remain within solution, depends heavily on the type of contaminant, the nature (or quality) of the DOC, the chemistry (e.g. pH and ionic strength) of the aqueous solution and the type of treatment process. We will carry out laboratory experiments to determine the extent to which these contaminants are bound to DOC at the point they enter the water treatment process and what is likely to happen as a result of the process, e.g. the extent to which contaminants are likely to be removed or remain in solution. Living organisms respond in various ways and on a spectrum of timescales when exposed to chemical contaminants. Some effects in organisms are immediate while others effects may be delayed and not show up for 10 or 20 years or more; for example, cancer in humans. We will draw on existing risk assessment approaches from national and international (EU) governmental agencies to evaluate the potential human health impacts of changes in levels of a range of contaminants under environmental change scenarios. Finally, we will bring together the findings of our research in the form of a Decision Support System (DSS) that will provide information to the water industry, the environmental agencies and other stake holders. The DSS will provide predictions of likely DOC trends under future climate change scenarios and the likely importance of predicted changes for wider water quality and human health.