Ahn Jong Ho, Grant Stanley B, Surbeck Cristiane Q, DiGiacomo Paul M, Nezlin Nikolay P, Jiang Sunny
Department of Chemical Engineering and Materials Science, Henry Samueli School of Engineering, University of California, Irvine, California 92697, USA.
Environ Sci Technol. 2005 Aug 15;39(16):5940-53. doi: 10.1021/es0501464.
Field studies were conducted to assess the coastal water quality impact of stormwater runoff from the Santa Ana River, which drains a large urban watershed located in southern California. Stormwater runoff from the river leads to very poor surf zone water quality, with fecal indicator bacteria concentrations exceeding California ocean bathing water standards by up to 500%. However, cross-shore currents (e.g., rip cells) dilute contaminated surf zone water with cleaner water from offshore, such that surf zone contamination is generally confined to < 5 km around the river outlet. Offshore of the surf zone, stormwater runoff ejected from the mouth of the river spreads out over a very large area, in some cases exceeding 100 km2 on the basis of satellite observations. Fecal indicator bacteria concentrations in these large stormwater plumes generally do not exceed California ocean bathing water standards, even in cases where offshore samples test positive for human pathogenic viruses (human adenoviruses and enteroviruses) and fecal indicator viruses (F+ coliphage). Multiple lines of evidence indicate that bacteria and viruses in the offshore stormwater plumes are either associated with relatively small particles (< 53 microm) or not particle-associated. Collectively, these results demonstrate that stormwater runoff from the Santa Ana River negatively impacts coastal water quality, both in the surf zone and offshore. However, the extent of this impact, and its human health significance, is influenced by numerous factors, including prevailing ocean currents, within-plume processing of particles and pathogens, and the timing, magnitude, and nature of runoff discharged from river outlets over the course of a storm.
开展了实地研究，以评估圣安娜河雨水径流对沿海水质的影响，该河流经加利福尼亚州南部一个大型城市流域。河流的雨水径流导致冲浪区水质极差，粪便指示菌浓度超过加利福尼亚州海洋浴场用水标准达500%。然而，沿岸流（如离岸流单元）会用离岸较清洁的水稀释受污染的冲浪区水体，因此冲浪区的污染通常局限于河口周围不到5公里的区域。在冲浪区离岸处，从河口排出的雨水径流会在非常大的区域扩散，根据卫星观测，在某些情况下面积超过100平方公里。即使在离岸样本检测出人类致病病毒（人类腺病毒和肠道病毒）和粪便指示病毒（F+噬菌体）呈阳性的情况下，这些大型雨水羽流中的粪便指示菌浓度通常也不会超过加利福尼亚州海洋浴场用水标准。多条证据表明，离岸雨水羽流中的细菌和病毒要么与相对较小的颗粒（<53微米）相关，要么与颗粒无关。总体而言，这些结果表明，圣安娜河的雨水径流会对沿海冲浪区和离岸的水质产生负面影响。然而，这种影响的程度及其对人类健康的意义受到多种因素的影响，包括盛行洋流、羽流内颗粒和病原体的处理过程，以及暴雨期间从河口排出的径流的时间、量级和性质。
