Haub School of Environment and Natural Resources, University of Wyoming, USA.
Haub School of Environment and Natural Resources, University of Wyoming, USA.
Sci Total Environ. 2023 Apr 1;867:161426. doi: 10.1016/j.scitotenv.2023.161426. Epub 2023 Jan 6.
44 million United States residents depend on private drinking water wells that are federally unregulated. Maintaining a clean groundwater supply for populations without access to public water systems is essential to supporting public health and falls to state regulators and private well owners. Yet, monitoring practices do not reflect the fact that groundwater pollution risk varies seasonally and with proximity to nearby surface-contaminated sites. Examination of nearly 50,000 well water samples across North Carolina, ranked second nationally in domestic well dependence and swine production, from 2013 to 2018 reveals a uniform sampling schedule but a variable risk of bacterial contamination within each calendar year. We document a threshold of 32.2 °C (90 °F) where total coliform bacteria and Escherichia coli (E. coli) detection in private well water spikes near swine lagoons but is absent from "upstream" wells and otherwise unexplained by a variety of other known contamination sites. Closing the gap between perceived and actual risks of drinking water contamination has potential to improve public health. State regulations and federal guidelines should consider coordinating domestic well sampling with seasonally and spatially fluctuating risks of groundwater contamination. Findings from this study are generalizable, having implications for other parts of the world with water sources that have the potential to get contaminated by nearby surface sources of human and animal waste, such as manure applications and leaching septic systems.
4400 万美国居民依赖于不受联邦监管的私人饮用水井。为无法获得公共供水系统的人群维持清洁的地下水供应对于支持公共卫生至关重要，这需要州监管机构和私人水井所有者共同努力。然而，监测实践并未反映出这样一个事实，即地下水污染风险会随季节和与附近受地表污染场地的距离而变化。对 2013 年至 2018 年北卡罗来纳州近 5 万份井水样本的检查显示，该州在国内水井依赖程度和养猪生产方面排名全国第二，尽管采样计划统一，但在每个日历年，细菌污染的风险存在差异。我们记录到一个阈值为 32.2°C（90°F），在靠近养猪场的私人水井水中，总大肠菌群和大肠杆菌（E. coli）的检测呈上升趋势，但在“上游”水井中则不存在这种情况，而且无法用其他各种已知的污染地点来解释。缩小对饮用水污染的感知风险和实际风险之间的差距有可能改善公共卫生。州法规和联邦指南应考虑将家庭水井抽样与地下水污染的季节性和空间波动风险相协调。本研究的结果具有普遍性，对世界上其他可能受到附近人类和动物粪便等地表污染源污染的水源的地区也具有启示意义，例如粪肥应用和渗滤式化粪池系统。
