Gentry Randall W, McCarthy John, Layton Alice, McKay Larry D, Williams Dan, Koirala Shesh R, Sayler Gary S
Center for Environmental Biotechnology, The University of Tennessee, Knoxville, TN 37996, USA.
J Environ Qual. 2006 Oct 27;35(6):2244-9. doi: 10.2134/jeq2006.0243. Print 2006 Nov-Dec.
This study analyzed the occurrence of Escherichia coli in a mixed land-use watershed with human, cattle, and wildlife fecal inputs located in a karstic geologic region using synoptic monitoring (samples taken throughout the watershed system) during base-flow conditions. The objective of the study was to evaluate the occurrence of E. coli during base-flow conditions for several months at seven different main channel and nine different tributary sampling sites in the Stock Creek watershed, a 49.3-km(2) basin located in Knoxville, TN. Escherichia coli densities were measured using the Colilert (Defined Substrate Technology) method. The instantaneous loads for E. coli were determined from measured flow rates and E. coli densities, with the highest loading rates observed in the late fall. The study indicated a strong correlation between E. coli load rate (colony-forming units [CFU]/d), 7-d antecedent precipitation, and turbidity. Water quality data, however, also exhibited a spatial dependency; for example, the E. coli load rate was better correlated with turbidity in the slower draining basin tailwater sampling sites than in the faster draining upstream headwater sampling sites. In the headwater sites, the E. coli load rate was better correlated with 7-d antecedent precipitation than turbidity.
本研究利用在基流条件下进行的全面监测（在整个流域系统采集样本），分析了位于岩溶地质区域、存在人类、牲畜和野生动物粪便输入的混合土地利用流域中大肠杆菌的出现情况。该研究的目的是评估在田纳西州诺克斯维尔市一个面积为49.3平方千米的斯托克溪流域的七个不同主河道和九个不同支流采样点，在基流条件下持续数月的大肠杆菌出现情况。使用科利尔特（定义底物技术）方法测量大肠杆菌密度。根据测量的流速和大肠杆菌密度确定大肠杆菌的瞬时负荷，秋季末观察到最高负荷率。该研究表明大肠杆菌负荷率（菌落形成单位[CFU]/天）、7天前期降水量和浊度之间存在很强的相关性。然而，水质数据也呈现出空间依赖性；例如，在排水较慢的流域尾水采样点，大肠杆菌负荷率与浊度的相关性比在排水较快的上游源头采样点更好。在源头采样点，大肠杆菌负荷率与7天前期降水量的相关性比与浊度的相关性更好。
