Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario, N6A 3K7, Canada.
Environment Canada, Canada Center for Inland Waters, Burlington, Ontario, L7S 1A1, Canada.
Water Res. 2017 Sep 15;121:204-212. doi: 10.1016/j.watres.2017.05.021. Epub 2017 May 9.
Fecal indicator bacteria (FIB) are known to accumulate in foreshore beach sand and pore water (referred to as foreshore reservoir) where they act as a non-point source for contaminating adjacent surface waters. While guidelines exist for sampling surface waters at recreational beaches, there is no widely-accepted method to collect sand/sediment or pore water samples for FIB enumeration. The effect of different sampling strategies in quantifying the abundance of FIB in the foreshore reservoir is unclear. Sampling was conducted at six freshwater beaches with different sand types to evaluate sampling methods for characterizing the abundance of E. coli in the foreshore reservoir as well as the partitioning of E. coli between different components in the foreshore reservoir (pore water, saturated sand, unsaturated sand). Methods were evaluated for collection of pore water (drive point, shovel, and careful excavation), unsaturated sand (top 1 cm, top 5 cm), and saturated sand (sediment core, shovel, and careful excavation). Ankle-depth surface water samples were also collected for comparison. Pore water sampled with a shovel resulted in the highest observed E. coli concentrations (only statistically significant at fine sand beaches) and lowest variability compared to other sampling methods. Collection of the top 1 cm of unsaturated sand resulted in higher and more variable concentrations than the top 5 cm of sand. There were no statistical differences in E. coli concentrations when using different methods to sample the saturated sand. Overall, the unsaturated sand had the highest amount of E. coli when compared to saturated sand and pore water (considered on a bulk volumetric basis). The findings presented will help determine the appropriate sampling strategy for characterizing FIB abundance in the foreshore reservoir as a means of predicting its potential impact on nearshore surface water quality and public health risk.
粪肠球菌（FIB）已知会在近岸沙滩和孔隙水（称为近岸储层）中积累，它们是污染邻近地表水的非点源。虽然有针对娱乐海滩地表水采样的指南，但目前还没有广泛接受的方法来采集沙/沉积物或孔隙水样本以进行 FIB 计数。不同采样策略在定量近岸储层中 FIB 丰度方面的效果尚不清楚。在六个具有不同砂质类型的淡水海滩进行了采样，以评估采样方法，用于描述近岸储层中大肠杆菌的丰度以及大肠杆菌在近岸储层不同组分（孔隙水、饱和砂、不饱和砂）之间的分配情况。评估了采集孔隙水（驱动点、铲取和小心挖掘）、不饱和砂（表层 1cm、表层 5cm）和饱和砂（沉积物芯、铲取和小心挖掘）的方法。还采集了踝关节深度的地表水样本进行比较。与其他采样方法相比，用铲子采集的孔隙水产生了最高的观察到的大肠杆菌浓度（仅在细砂海滩上具有统计学意义）和最低的变异性。采集表层 1cm 的不饱和砂比采集表层 5cm 的砂产生的浓度更高且更具变异性。使用不同的方法采集饱和砂时，大肠杆菌浓度没有统计学差异。总体而言，与饱和砂和孔隙水相比（按总体积计），不饱和砂的大肠杆菌含量最高。本研究结果将有助于确定用于描述近岸储层中 FIB 丰度的适当采样策略，以便预测其对近岸地表水质量和公共健康风险的潜在影响。
