Stanford University, Environmental and Water Studies, Department of Civil & Environmental Engineering, 473 Via Ortega, Stanford, CA 94305, USA.
Water Res. 2011 Feb;45(4):1752-62. doi: 10.1016/j.watres.2010.11.032. Epub 2010 Nov 30.
Fecal pollution enters coastal waters through multiple routes, many of which originate from land-based activities. Runoff from pervious and impervious land surfaces transports pollutants from land to sea and can cause impairment of coastal ocean waters. To understand how land use practices and water characteristics influence concentrations of fecal indicator bacteria (FIB) and pathogens in natural waters, fourteen coastal streams, rivers, and tidal lagoons, surrounded by variable land use and animal densities, were sampled every six weeks over two years (2008 & 2009). Fecal indicator bacteria (FIB; Escherichia coli and Enterococci) and Salmonella concentrations, the occurrence of Bacteroidales human, ruminant, and pig-specific fecal markers, E. coli O157:H7, and Shiga toxin (stx) genes present in E. coli, were measured. In addition, environmental and climatic variables (e.g., temperature, salinity, rainfall), as well as human and livestock population densities and land cover were quantified. Concentrations of FIB and Salmonella were correlated with each other, but the occurrence of host-specific Bacteroidales markers did not correlate with FIB or pathogens. FIB and Salmonella concentrations, as well as the occurrence of E. coli harboring stx genes, were positively associated with the fraction of the surrounding subwatershed that was urban, while the occurrence of E. coli O157:H7 was positively associated with the agricultural fraction. FIB and Salmonella concentrations were negatively correlated to salinity and temperature, and positively correlated to rainfall. Areal loading rates of FIB, Salmonella and E. coli O157:H7 to the coastal ocean were calculated for stream and river sites and varied with land cover, salinity, temperature, and rainfall. Results suggest that FIB and pathogen concentrations are influenced, in part, by their flux from the land, which is exacerbated during rainfall; once waterborne, bacterial persistence is affected by water temperature and salinity.
粪便污染通过多种途径进入沿海水域，其中许多途径源自陆基活动。透水和不透水的地表径流将污染物从陆地输送到海洋，从而导致沿海水域受损。为了了解土地利用方式和水特性如何影响天然水中粪便指示菌（FIB）和病原体的浓度，在两年（2008 年和 2009 年）内，每六周对 14 个沿海溪流、河流和潮汐泻湖进行了采样，这些溪流、河流和潮汐泻湖周围的土地利用和动物密度各不相同。测定了粪便指示菌（FIB；大肠杆菌和肠球菌）和沙门氏菌浓度、存在于大肠杆菌中的 Bacteroidales 人、反刍动物和猪特异性粪便标记物、大肠杆菌 O157：H7 和志贺毒素（stx）基因、环境和气候变量（例如温度、盐度、降雨量）以及人口密度和土地覆盖。此外，还测定了粪便指示菌（FIB）和沙门氏菌的浓度，以及存在于大肠杆菌中的宿主特异性 Bacteroidales 标记物与 FIB 或病原体之间的相关性。FIB 和沙门氏菌浓度与彼此相关，但宿主特异性 Bacteroidales 标记物的发生与 FIB 或病原体无关。FIB 和沙门氏菌浓度以及携带 stx 基因的大肠杆菌的发生与周围子流域中城市部分的比例呈正相关，而大肠杆菌 O157：H7 的发生与农业部分呈正相关。FIB 和沙门氏菌浓度与盐度和温度呈负相关，与降雨量呈正相关。对溪流和河流站点向沿海水域的 FIB、沙门氏菌和大肠杆菌 O157：H7 的面积负荷率进行了计算，其值随土地覆盖、盐度、温度和降雨量而变化。结果表明，FIB 和病原体浓度部分受其从陆地流入的影响，而降雨会加剧这种影响；一旦进入水体，细菌的持久性则受水温盐度的影响。
