Worldwide, fecal indicator bacteria (FIB) evidence coastal water contamination for which sources are unknown. Here, for two FIB-impacted Santa Barbara recreational beaches, hypothesized fecal sources were investigated over three dry seasons (summers) using nearly 2000 field samples of water (ocean, creek, groundwater), sand, sediments, effluent and fecal sources. In years 1 and 2, gull and dog feces were identified as the probable main FIB sources to surf zone waters, yet HF183 human fecal markers were consistently detected. Determining HF183 sources was therefore prioritized, via year 3 sub-studies. In lower watersheds, human and dog wastes were mobilized by small storms into creeks, but no storm drain outfalls or creeks discharged into surf zones. Beach area bathrooms, sewers, and a septic system were not sources: dye tracing discounted hydraulic connections, and shallow groundwater was uncontaminated. Sediments from coastal creeks and downstream scour ponds, nearshore marine sediments, and sands from inter- and supratidal zones contained neither HF183 nor pathogens. Two nearby wastewater treatment plant (WWTP) outfalls discharged HF183 into plumes that were either deep or distant with uncertain onshore transport. Regardless, local sources were evidenced, as surf zone HF183 detection rates mostly exceeded those offshore and nearshore (around boat anchorages). The presence of swimmers was associated with surf zone HF183, as swimmer counts (on weekdays, holidays, weekends, and during races) significantly correlated (p<0.05, n = 196) to HF183 detections. Besides comprehensively assessing all possible fecal sources, this study provides new explanations of chronic low-level human markers in recreational beach surf zones, suggesting likely lowest achievable HF183 thresholds.

在世界范围内，粪便指示菌 (FIB) 证明了来源不明的沿海水污染。在这里，对于两个受 FIB 影响的圣巴巴拉休闲海滩，使用近 2000 个现场水样（海洋、小溪、地下水）、沙子、沉积物、污水和粪便来源，在三个旱季（夏季）中调查了假设的粪便来源。在第 1 年和第 2 年，海鸥和狗的粪便被确定为冲浪区水域可能的主要 FIB 来源，但始终检测到 HF183 人类粪便标记物。因此，通过第 3 年的子研究，确定 HF183 的来源被列为优先事项。在较低的流域，人和狗的排泄物被小风暴转移到小溪中，但没有雨水排放口或小溪排入海浪区。海滩区的浴室、下水道和化粪池系统不是来源：染料追踪降低了水力连接，浅层地下水未受污染。来自沿海小溪和下游冲刷池的沉积物、近岸海洋沉积物以及来自潮间带和潮上带的沙子既不含 HF183，也不含病原体。附近的两个污水处理厂 (WWTP) 排放口将 HF183 排放到深或远且陆上运输不确定的羽流中。无论如何，当地来源得到了证明，因为冲浪区 HF183 的检测率大多超过近海和近岸（船锚地附近）的检测率。游泳者的存在与冲浪区 HF183 相关，因为游泳者数量（工作日、假期、周末和比赛期间）显着相关（来自潮间带和潮上带的沙子既不含 HF183，也不含病原体。附近的两个污水处理厂 (WWTP) 排放口将 HF183 排放到深或远且陆上运输不确定的羽流中。无论如何，当地来源得到了证明，因为冲浪区 HF183 的检测率大多超过近海和近岸（船锚地附近）的检测率。游泳者的存在与冲浪区 HF183 相关，因为游泳者数量（工作日、假期、周末和比赛期间）显着相关（来自潮间带和潮上带的沙子既不含 HF183，也不含病原体。附近的两个污水处理厂 (WWTP) 排放口将 HF183 排放到深或远且陆上运输不确定的羽流中。无论如何，当地来源得到了证明，因为冲浪区 HF183 的检测率大多超过近海和近岸（船锚地附近）的检测率。游泳者的存在与冲浪区 HF183 相关，因为游泳者数量（工作日、假期、周末和比赛期间）显着相关（由于冲浪区 HF183 的检测率大多超过近海和近岸（船锚地周围）。游泳者的存在与冲浪区 HF183 相关，因为游泳者数量（工作日、假期、周末和比赛期间）显着相关（由于冲浪区 HF183 的检测率大多超过近海和近岸（船锚地周围）。游泳者的存在与冲浪区 HF183 相关，因为游泳者数量（工作日、假期、周末和比赛期间）显着相关（p <0.05，n  = 196) 到 HF183 检测。除了全面评估所有可能的粪便来源外，这项研究还为休闲海滩冲浪区的慢性低水平人类标记提供了新的解释，表明可能达到的最低 HF183 阈值。