Schiff Kenneth C, Morton Jessica, Weisberg Stephen B
Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683 USA.
Mar Environ Res. 2003 Jul-Aug;56(1-2):245-53. doi: 10.1016/S0141-1136(02)00333-1.
Santa Monica Bay (SMB) beaches are the most heavily used in the U.S.A., despite an increased number of water quality postings over the last several years. To assess whether water quality problems are concentrated at a small number of chronically affected sites or whether the problems are widely distributed, we compiled 5 years of monitoring data collected at 59 sites, 22 of which are sampled daily. Other locally available rainfall and sewage spill monitoring information data were added to this data set to assess whether sewage spills, dry-weather runoff, or wet-weather runoff contribute the most to exceedences of water quality thresholds. Approximately 13% of the shoreline mile-days along monitored beaches in SMB exceeded the State of California's beach water quality standards during the 5-year study period. Most of the water quality exceedences occurred near urban runoff drains even though areas affected by drains represent only a small portion of the total shoreline. Although storms are relatively infrequent in southern California, the extent of water quality exceedences resulting from storm water runoff was similar to the extent of water quality exceedences found during dry weather. Sewage spills, while potentially more serious because they lead to beach closures rather than to the more limited posting of warning signs, represented less than 0.1% of the shoreline mile-days that exceeded water quality thresholds. During dry weather conditions, most of the water quality problems occurred near five of the largest drains and at two beach areas that have unique physical characteristics, which limited mixing, dispersion, and dilution. During wet weather conditions, water quality problems were more widespread.
圣莫尼卡湾（SMB）的海滩是美国使用最为频繁的海滩，尽管在过去几年里水质公告数量有所增加。为了评估水质问题是集中在少数几个长期受影响的地点，还是广泛分布，我们汇总了在59个地点收集的5年监测数据，其中22个地点每天进行采样。其他当地可得的降雨和污水泄漏监测信息数据也被添加到该数据集中，以评估污水泄漏、旱季径流或雨季径流对水质阈值超标影响最大。在为期5年的研究期间，SMB监测海滩沿线约13%的海岸线英里日数超过了加利福尼亚州的海滩水质标准。即使受排水口影响的区域仅占总海岸线的一小部分，但大多数水质超标情况都发生在城市径流排水口附近。尽管南加州的风暴相对较少，但雨水径流导致的水质超标程度与旱季发现的水质超标程度相似。污水泄漏虽然可能更严重，因为它们会导致海滩关闭，而不仅仅是张贴更有限的警告标志，但在超过水质阈值的海岸线英里日数中所占比例不到0.1%。在旱季，大多数水质问题发生在五个最大的排水口附近以及两个具有独特物理特征、限制混合、扩散和稀释的海滩区域。在雨季，水质问题分布更为广泛。
