Beach sands along the California coast are diffuse sources of fecal bacteria to coastal waters
Beach sands along the California coast are diffuse sources of fecal bacteria to coastal waters
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DOI：
10.1021/es062822n
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发表时间：
2007-07-01
影响因子：
11.4
通讯作者：
Boehm, Alexandria B.
中科院分区：
文献类型：
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作者：
Yamahara, Kevan M.;Layton, Blythe A.;Boehm, Alexandria B.
粪便指示菌 (FIB) 在加利福尼亚州 (CA) 的沙滩上几乎无处不在。沙子是从加州海岸沿线的 55 个海滩收集的。 91% 的海滩在沙子中检测到肠球菌 (ENT)，而 62% 的海滩则检测到大肠杆菌 (El.)。假定的细菌源（例如河流）的存在、避浪的程度以及周围的土地利用解释了海滩之间 ENT 和 EC 密度差异的显着部分（p < 0.05）。沙子特性，包括水分含量、有机碳和细粉百分比，仅显着 (p < 0.05) 影响海滩沙子中的 EC 密度。我们对 163 个沙子样本中的 34 个进行了沙门氏菌检测，但没有检测到这种细菌病原体。在加利福尼亚州情人角 (Lovers Point, CA) 的海滩沙子中耳鼻喉科密度较高的单一避浪海滩上，研究了 FIB 从沙子传输到海洋的可能性。我们在 24 小时内收集了暴露和淹没的沙子以及水的样本，以便比较 ENT 在沙子和水柱中的消失或出现。裸露沙子的 ENT 密度明显高于水下沙子，最高密度位于高潮线附近。水柱 ENT 密度开始较低，在第一次洪水期间急剧增加，并在研究的其余时间缓慢下降。在第一次涨潮时，进入水体的ENT数量几乎相当于暴露的沙子被海水淹没时损失的ENT数量。最初流入后近岸 ENT 浓度的下降可以用 ENT 死亡和清澈海水稀释来解释。虽然 LF 的水和沙子中的一些 ENT 可能是人类起源的，因为它们对 esp 基因呈阳性，但其他 ENT 缺乏 esp 基因，因此其起源是模棱两可的。 LP 的后续采样显示，水和沙子中存在人类特有的拟杆菌标记。
Fecal indicator bacteria (FIB) are nearly ubiquitous in California (CA) beach sands. Sands were collected from 55 beaches along the CA coast. Ninety-one percent of the beaches had detectable enterococci (ENT) while 62% had detectable E. coli (El.) in their sands. The presence of a putative bacterial source (such as a river), the degree of wave shelter, and surrounding land use explained a significant (p < 0.05) fraction of the variation in both ENT and EC densities between beaches. Sand characteristics including moisture content, organic carbon, and percent fines, significantly (p < 0.05) influenced only EC densities in beach sand. We assayed 34 of 163 sand samples for salmonellae, but did not detect this bacterial pathogen. The potential for FIB to be transported from the sand to sea was investigated at a single wave-sheltered beach with high densities of ENT in beach sand: Lovers Point, CA (LP). We collected samples of exposed and submerged sands as well as water over a 24 h period in order to compare the disappearance or appearance of ENT in sand and the water column. Exposed sands had significantly higher densities of ENT than submerged sands with the highest densities located near the high tide line. Water column ENT densities began low, increased sharply during the first flood tide and slowly decreased over the remainder of the study. During the first flood tide, the number of ENT that entered the water column was nearly equivalent to the number of ENT lost from exposed sands when they were submerged by seawater. The decrease in nearshore ENT concentrations after the initial influx can be explained by ENT die-off and dilution with clear ocean water. While some ENT in the water and sand at LF might be of human origin because they were positive for the esp gene, others lacked the esp gene and were therefore equivocal with respect to their origin. Follow-up sampling at LP revealed the presence of the human specific Bacteroides marker in water and sand.