ABSTRACT
The patterns of surface water composition are controlled by a wide range of factors and processes, including catchment geology, diffuse and point source inputs from anthropogenic sources, catchment topography and hydrology , and in-stream processes (see e.g. Jarvie et al., 2002). As we have seen in the previous chapters, catchment geology determines the background concentrations in soils and groundwater, and thus also in surface water. Catchment topography and hydrology play important roles in the transfer of contaminants from the catchment surface to the drainage network. After contaminants have entered the surface water via overland or underground pathways or a combination of both, in-stream biogeochemical processes modify their concentrations. Thus, to understand, interpret, or predict patterns in surface water composition, it is important to understand the processes and patterns in soil and groundwater, and the physical and biogeochemical conditions affecting the surface water (see e.g. Bouwman et al., 2013).
