Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea.
Water Res. 2010 Apr;44(7):2189-202. doi: 10.1016/j.watres.2009.12.051. Epub 2010 Jan 11.
Gwangju Creek (GJC) in Korea, which drains a highly urbanized watershed, has suffered from substantial fecal contamination, thereby limiting the beneficial use of the water in addition to threatening public health. In this study, to quantitatively estimate the sinks and sources of fecal indicator bacteria (FIB) in GJC under varying meteorological conditions, two FIB (i.e., Escherichia coli and enterococci bacteria) were monitored hourly for 24h periods during both wet and dry weather conditions at four sites along GJC, and the collected data was subsequently used to develop a spatiotemporal FIB prediction model. The monitoring data revealed that storm washoff and irradiational die-off by sunlight are the two key processes controlling FIB populations in wet and dry weather, respectively. FIB populations significantly increased during precipitation, with greater concentrations occurring at higher rainfall intensity. During dry weather, FIB populations decreased in the presence of sunlight in daytime but quickly recovered at nighttime due to continuous point-source inputs. In this way, the contributions of the key processes (i.e., irradiational die-off by sunlight, settling, storm washoff, and resuspension) to the FIB levels in GJC under different meteorological conditions were quantitatively estimated using the developed model. The modeling results showed that the die-off by sunlight is the major sink of FIB during the daytime in dry weather with a minor contribution from the settling process. During wet weather, storm washoff and resuspension are equally important processes that are responsible for the substantial increase of FIB populations.
韩国光州溪（GJC）流经一个高度城市化的流域，受到严重的粪便污染，这不仅限制了水的有益用途，还威胁到公众健康。在这项研究中，为了定量估计在不同气象条件下 GJC 中粪便指示菌（FIB）的汇和源，在 GJC 的四个地点，分别在干湿天气条件下，每小时监测两种 FIB（即大肠杆菌和肠球菌）24 小时，收集的数据随后用于开发时空 FIB 预测模型。监测数据显示，暴雨冲刷和阳光辐射衰减是控制干湿天气中 FIB 种群的两个关键过程。在降水期间，FIB 种群显著增加，降水强度越大，浓度越高。在干燥天气中，白天阳光会导致 FIB 种群减少，但由于持续的点源输入，夜间会迅速恢复。通过这种方式，使用开发的模型定量估计了不同气象条件下 GJC 中关键过程（即阳光辐射衰减、沉降、暴雨冲刷和再悬浮）对 FIB 水平的贡献。建模结果表明，在干燥天气的白天，阳光辐射衰减是 FIB 的主要汇，沉降过程的贡献较小。在雨季，暴雨冲刷和再悬浮是同等重要的过程，它们是 FIB 种群大量增加的原因。
