In view of the concerns regarding contaminant transport and removal after water pollution incidents, this study focuses on the temporal and spatial evolutions of concentration distribution and removal performance in channel flows with floating vegetation islands (FVIs). For a typical case of instantaneous and uniform contaminant release, the analytical solution of the spatial concentration distribution is deduced based on the multi-scale perturbation method. With the combined effects of advection and vegetation absorption, a tremendous concentration gradient forms on cross-sections and cannot be smeared out until the contaminant is completely removed. Both the vertical and longitudinal concentration distributions are reshaped in different degrees due to the different intensities of vegetation absorption. The stronger the vegetation absorption is, the greater the vertical distribution of the mass proportion deviates from that for pure dispersion. By establishing the relationships of the removal rate and removal efficiency with the residence time, distance and absorption parameter based on the control volume analysis, the temporal and spatial evolutions of the removal performances with different absorption intensities are assessed quantitatively. The significantly reduced critical lengths and durations of influenced regions confirm the ecological effects of FVIs from the perspective of hydraulic research.

鉴于水污染事件后对污染物迁移和清除的担忧，本研究重点研究了具有浮动植被岛（FVI）的河道流中浓度分布和清除性能的时空演变。针对污染物瞬时均匀释放的典型案例，基于多尺度摄动法推导出空间浓度分布的解析解。在平流和植被吸收的综合作用下，横截面形成了巨大的浓度梯度，直到污染物完全清除后才能抹去。由于植被吸收强度的不同，垂直和纵向浓度分布都发生了不同程度的重塑。植被吸收越强，质量比例的垂直分布与纯分散的偏差越大。通过基于控制体积分析建立去除率和去除效率与停留时间、距离和吸收参数的关系，定量评估不同吸收强度下去除性能的时空演变。受影响区域的临界长度和持续时间显着缩短，从水力研究的角度证实了 FVI 的生态效应。定量评估不同吸收强度的去除性能的时空演变。受影响区域的临界长度和持续时间显着缩短，从水力研究的角度证实了 FVI 的生态效应。定量评估不同吸收强度的去除性能的时空演变。受影响区域的临界长度和持续时间显着缩短，从水力研究的角度证实了 FVI 的生态效应。