Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
Water Res. 2011 Feb;45(5):1951-60. doi: 10.1016/j.watres.2010.12.030. Epub 2011 Jan 8.
Faecal bacteria exist in both free-living and attached forms in surface waters. The deposition of sediments can take faecal bacteria out of the water column and to the bed. The sediments can subsequently be re-suspended into the water column, which can then lead to the re-suspension of the faecal bacteria of the attached form back into the water column, where it may desorb from the sediments. Therefore, the fate and transport of faecal bacteria is highly related to the governing sediment transport processes, particularly where these processes are significant. However, little attempt has been made to model such processes in terms of predicting the impact of the sediment fluxes on faecal bacteria levels. Details are given of the refinement of a numerical model of faecal bacteria transport, where the sediment transport processes are significant. This model is based on the model DIVAST (Depth Integrated Velocities And Solute Transport). Analytical solutions for steady and uniform flow conditions were derived and used to test the sediment-bacteria interaction model. After testing the sediment-bacteria interaction model favourably against known results, the model was then set up for idealized case studies to investigate the effects of sediment on bacteria concentrations in the water column. Finally the model was applied to a simplified artificial flooding study to investigate the impact of suspended sediment fluxes on the corresponding bacteria transport processes. The model predictions have proved to be encouraging, with the results being compared to field measurements.
粪便细菌以自由生活和附着两种形式存在于地表水。沉积物的沉积可以将粪便细菌从水柱中取出并带到床层。随后，沉积物可以重新悬浮到水柱中，这可能导致附着形式的粪便细菌重新悬浮到水柱中，并从沉积物中解吸。因此，粪便细菌的归宿和输移与控制沉积物输移过程密切相关，特别是在这些过程显著的情况下。然而，在预测沉积物通量对粪便细菌水平的影响方面，很少有人试图对这些过程进行建模。本文详细介绍了对粪便细菌输移数值模型的改进，其中沉积物输移过程是显著的。该模型基于 DIVAST（深度积分速度和溶质输移）模型。推导出了稳态和均匀流条件下的解析解，并将其用于测试泥沙-细菌相互作用模型。在对泥沙-细菌相互作用模型进行了有利的测试后，针对理想案例研究建立了该模型，以研究沉积物对水柱中细菌浓度的影响。最后，将该模型应用于简化的人工洪水研究，以调查悬浮泥沙通量对相应细菌输移过程的影响。模型预测结果令人鼓舞，并将结果与现场测量结果进行了比较。
