Abstract：
Coastal marine environments are increasingly affected by anthropogenic impacts, such as the release of sewage at outfall sites and agricultural run-off. Fecal pollution introduced to the sea through these activities poses risks of spreading microbial diseases and disseminating antibiotic resistant bacteria and their genes. The study area of this research, Bore beach, is situated between two such point sources, an outfall site where treated sewage is released 1 km off the coast and a stream that carries run-off from an agricultural area to the northern end of the beach. In order to investigate whether and to what extent fecal contamination from the sewage outfall reached the beach, we used microbial source tracking, based on whole community analysis. Samples were collected from sea water at varying distances from the sewage outfall site and along the beach, as well as from the sewage effluent and the stream. Amplicon sequencing of 16S rRNA genes from all the collected samples was carried out at two time points (June and September). In addition, the seawater at the sewage outfall site and the sewage effluent were subject to shotgun metagenomics. To estimate the contribution of the sewage effluent and the stream to the microbial communities at Bore beach, we employed SourceTracker2, a program that uses a Bayesian algorithm to perform such quantification. The SourceTracker2 results suggested that the sewage effluent is likely to spread fecal contamination towards the beach to a greater extent than anticipated based on the prevailing sea current. The estimated mixing proportions of sewage at the near-beach site (P4) were 0.22 and 0.035% in June and September, respectively. This was somewhat below that stream\'s contribution in June (0.028%) and 10-fold higher than the stream\'s contribution in September (0.004%). Our analysis identified a sewage signal in all the tested seawater samples.
摘要：
沿海海洋环境越来越受到人为影响，例如排污口和农业径流的污水排放。通过这些活动引入海洋的粪便污染带来了传播微生物疾病和传播抗生素抗性细菌及其基因的风险。本研究的研究领域，钻孔海滩，位于两个这样的点源之间，一个排水口，处理后的污水在离海岸1公里的地方被释放，一条从农业区到海滩北端的河流被输送。为了调查排污口的粪便污染是否以及在多大程度上到达海滩，我们使用了微生物来源追踪，基于整个社区的分析。样本是从距排污口地点及沿海滩不同距离的海水中收集的,以及污水和溪流。在两个时间点(6月和9月)对来自所有收集的样品的16SrRNA基因进行扩增子测序。此外,污水排放口的海水和污水都接受了鸟枪宏基因组学研究。为了估计污水和溪流对Bore海滩微生物群落的贡献，我们采用了SourceTracker2，这是一个使用贝叶斯算法来执行这种量化的程序。SourceTracker2结果表明，根据当前的海流，污水可能会比预期的更大程度地向海滩传播粪便污染。在六月及九月,近滩地盘(P4)污水的混合比例估计为0.22%及0.035%,分别。这略低于6月份该流的贡献（0.028％），比9月份该流的贡献（0.004％）高10倍。我们的分析确定了所有测试海水样品中的污水信号。
