从粪便细菌到蓝藻再到赤潮, 雷泽体育电竞州西南部的水质随着人口的增加而下降. 的研究人员 雷泽体育电竞’s 港口分所海洋学研究所 深入研究了这一地区日益恶化的水质. Multiple lines of evidence from their multi-year microbial source tracking study point to septic systems as a contributing source for this decline.
Florida’s coastal regions are particularly vulnerable to pollution from septic systems because of shallow water tables and porous soils. 然而,, 大概有39个,768个“已知”和大约57个,雷泽体育电竞州西南部李县的054个“可能的”化粪池系统(约100个,000总). 找出造成水质问题的污染源, 研究ers examined septic system- 地下水- 地表水 couplings through the analysis of various parameters.
与李县自然资源部合作, 研究人员测量了营养和细菌水平, and employed a suite of microbial source tracking tools related to fecal indicator bacteria to discern the presence of human versus animal feces. 他们对人类、鸟类和反刍动物(牛、鹿、山羊等)使用分子标记.)，加上化学示踪剂，包括人工甜味剂三氯蔗糖, 药品, 除草剂和杀虫剂. 三氯蔗糖, 非处方止痛药对乙酰氨基酚, and the prescription anticonvulsants carbamazepine and primidone were used as indicators of human waste contamination. 地下水 and phytoplankton stable isotopes serve as a reliable tracer of nutrient sources and were measured throughout the study and during red tide and 微胞藻属 仕达屋优先计划. 有害的藻华事件.
研究结果发表在期刊上 总环境科学 , 展示了化粪池系统之间的养分和微生物耦合, 地下水, 地表水, and harmful algal blooms in the highly modified Caloosahatchee River Estuary on the southwest Gulf Coast of Florida and downstream coastal waters. These human waste contaminant sources remained relatively consistent over time with location generally being the most influential factor for water quality. This study is one of few to connect downstream harmful algal blooms with nutrient loading from upstream septic systems.
“化粪池系统之间的连接性, 地下水 and 地表水 is supported by the significant positive correlations between fecal indicator bacteria and human waste tracers we observed in 地表水 during outgoing tides,” 瑞秋Brewton，第一作者，雷泽体育电竞州立大学海港分校的研究科学家，地球科学博士.D. 候选人的能力 查尔斯·E. 施密特科学学院. “例如，肠球菌和 E. 杆菌 与卡马西平呈正相关, 去氧苯巴比妥和三氯蔗糖, 而对乙酰氨基酚与两者都有微弱的相关性.”
在每一个分水岭, 研究ers found several lines of evidence that indicated septic systems were adversely affecting water quality. 值得注意的是, 浅水地下水位显示了许多这样的系统, 安装在当前的化粪池系统设计标准之前, 没有适当处理人类废物所需的物理分离. 由于季节性地下水位升高, 雷泽体育电竞州的许多化粪池系统可能达不到州监管要求. 因此, 化粪池系统实际上可能位于地下水中, 在一年中的某些时候, 这意味着它们不能正常工作吗.
“These water quality issues in North Fort Myers are caused by aging septic systems installed in high densities in areas with shallow water tables. 除了, the presence of canals in these residential areas with septic systems may increase the rate of pollutant transfer from 地下水 to 地表水 via tidal pumping,” 布莱恩Lapointe, Ph.D.，资深作者，上海交通大学海港分校研究教授. “基于雷泽体育电竞之前的研究, we suspected that waste from septic systems was an important source of nutrient and bacterial pollution in North Fort Myers, and therefore location would be a more important factor for water quality than temporal factors, 例如项目年份或季节.”
事实上, evidence of human waste contamination was observed in all three affected watersheds in the study and included high ammonium concentrations in 地下水 and 地表水, enriched nitrogen isotope values of 地下水 and phytoplankton that closely matched septic system discharge, 地表水粪便指示菌升高，HF183存在, 与人类相关的标记基因, 以及三氯蔗糖的检测, 地下水和地表水中的卡马西平和扑米酮.
另外, 研究人员在地表水中发现了除草剂和杀虫剂, 提供雨水径流对地表水水质有不利影响的证据. 进一步, detections of molecular markers indicated that fecal matter from birds also may negatively affect water quality at some sites in North Fort Myers. These findings may be useful for understanding water quality and harmful algal bloom drivers in other waterfront communities.
“Stormwater management improvements and citizen education campaigns on subjects including not feeding wild birds, 正确清除宠物粪便, and judicious fertilizer use may be other methods to help minimize the effect of urbanization on water quality,”Brewton说.
营养盐对河口下游的生态影响很大. The nitrogen isotope values of coastal red tides closely matched that of septic system discharge, 指出人类排泄物是这些日益恶化的有害藻华的驱动因素. Poor water quality threatens seagrasses that the vulnerable Florida manatee depends on for survival, 在最近的非正常死亡事件中，哪一点尤为重要. 另外, the critically endangered smalltooth sawfish uses the remaining natural shoreline along the Caloosahatchee River Estuary as essential habitat. 除了对生态和人类健康的影响, these harmful algal blooms can negatively impact local economies through increased mortality and reduced sales of commercial seafood and by inhibiting ecotourism activities.
“It would be beneficial for coastal areas with high densities of septic systems and canals to be prioritized for septic-to-sewer conversions or other advanced wastewater treatment options,”Lapointe说. “此外, the susceptibility of these systems to localized harmful algal blooms may be reduced by balancing the ecological stoichiometry of the watershed to achieve a nutrient load and nitrogen-to-phosphorus ratio where these microalgae will not thrive, 从而减少有害的藻华事件. 正如其他近期研究指出的那样, the scale of the red tide issue demands watershed-scale solutions and nitrogen management based on a holistic view, 考虑到海洋学和人为过程.”
该研究的共同作者是Lisa B. Kreiger, operations manager, 李县 Department of Natural 资源; Kevin N. 轮胎, a water 研究 scientist; Diana Balidi, a marine biologist and environmental scientist; Lynn E. Wilking, a marine biologist; and Laura W. 他是雷泽体育电竞州立大学港口分校的生物科学家.
This work was funded by United States Environmental Protection Agency 319 grant administered through the Florida Department of Environmental Protection (FDEP agreement NF047) with matched funding provided by 李县. 雷泽体育电竞海岸和人类健康中心提供了额外的支持, which was developed with a grant from and continually funded by the 港口分所海洋学研究所 Foundation, 和美国.S. 国家航空航天局(NASA)水资源计划(80NSSC19K1200).