污染物在流域水土环境中存在复杂的源汇关系，在水土环境中的转化作用主要受控于各种水‒ 土界面过程，为此，水土环境污染治理需将水土环境作为一个整体，通过跨介质归因识别找到真正的污染源，然后进行跨介质治理。本文首先分析了污染物在流域水土环境中的跨水‒ 土介质迁移过程以及主要影响因素，在此基础上提出了流域水土环境跨介质调控原理及关键过程，主要包括流域水土环境污染跨介质归因识别和流域水土环境污染跨介质治理。同时，重点阐述了污染物在河道外的土壤‒ 水界面、坡面‒ 河道界面，河道内的水‒ 沉积物界面（包括河床潜流带和侧向岸边潜流带的水‒固界面）和水‒ 悬浮颗粒物界面过程在跨介质去除中的重要作用，并采用实际案例阐述了流域非点源污染物的跨介质控制、河流含氮化合物的跨介质去除以及湖泊氮磷的跨介质去除方法等。研究结果可为流域水土环境污染防治提供科学依据。

Pollutants have complex source-sink relationships in water and soil environments at a catchment scale, and the transformation of pollutants in water and soil environments is primarily controlled by various water-soil interface processes. Therefore, the control of water and soil environmental pollution should consider water and soil environments as a whole, identify the real pollution source through cross-medium attribution analysis, and then control the pollution with cross-medium treatment. We first analyze the crossmedium migration processes of pollutants and the major influencing factors. Then we propose the principle and key process of crossmedium regulation, namely, cross-medium attribution identification and cross-medium treatment of water and soil environmental pollution. Moreover, we expound the important role of the processes of the following interfaces in cross-medium removal of pollutants: soil-water and slope-channel interfaces outside river channels, as well as water-sediment and water-suspended particulate matter interfaces in river channels (including water-solid interfaces in the riverbed and lateral shore hyporheic zones). Furthermore, cross-medium control of non-point source pollutants in watershed, cross-medium removal of nitrogen-containing compounds from rivers, and cross-medium removal of nitrogen and phosphorus from lakes are illustrated with practical cases. The research results can provide a scientific basis for the control and treatment of water and soil pollution.