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Abstract：
This study investigated causes of persistent fecal indicator bacteria (FIB) in beach sand under the pier in Santa Monica, CA. FIB levels were up to 1,000 times higher in sand underneath the pier than that collected from adjacent to the pier, with the highest concentrations under the pier in spring and fall. Escherichia coli (EC) and enterococci (ENT) under the pier were significantly positively correlated with moisture (ρ = 0.61, p < 0.001, n = 59; ρ = 0.43, p < 0.001, n = 59, respectively), and ENT levels measured by qPCR (qENT) were much higher than those measured by membrane filtration (cENT). Microcosm experiments tested the ability of EC, qENT, cENT, and general Bacteroidales (GenBac) to persist under in-situ moisture conditions (10% and 0.1%). Decay rates of qENT, cENT, and GenBac were not significantly different from zero at either moisture level, while decay rates for EC were relatively rapid during the microcosm at 10% moisture (k = 0.7 days-1). Gull/pelican marker was detected at eight of 12 sites and no human-associated markers (TaqHF183 and HumM2) were detected at any site during a one-day site survey. Results from this study indicate that the high levels of FIB observed likely stem from environmental sources combined with high persistence of FIB under the pier.
摘要：
这项研究调查了圣莫尼卡码头下海滩沙中持久性粪便指示细菌（FIB）的原因，CA.码头下方的沙子中的FIB水平比从码头附近收集的沙子高1000倍，在春季和秋季码头下浓度最高。桥墩下大肠杆菌(EC)和肠球菌(ENT)与水分呈极显著正相关(ρ=0.61,p<0.001,n=59;ρ=0.43,p<0.001,n=59),通过qPCR（qENT）测量的ENT水平远高于通过膜过滤（CENT）测量的ENT水平。微观世界实验测试了EC的能力，QENT,CENT,和普通拟杆菌(GenBac)在原位水分条件(10%和0.1%)下持续存在。QENT的衰减率，CENT,和GenBac在任一湿度水平下都与零没有显着差异，而在微观世界中，在10％的水分（k=0.7天-1）下，EC的衰减率相对较快。在为期一天的现场调查中，在12个站点中的8个站点中检测到了Gull/pelican标记，在任何站点均未检测到与人类相关的标记（TaqHF183和HumM2）。这项研究的结果表明，观察到的高水平FIB可能源于环境来源，再加上码头下FIB的高持久性。
