Transfer in aquatic systems

When rain falls over land some drain off the surface directly into surface water courses in surface runoff. A further part of the incoming rainwater percolates into the soil and passes more slowly into either surface waters or underground reservoirs. Water held in rock below the surface is termed groundwater, and a rock formation that stores and transmits water in useful quantities is termed an aquifer. Water that passes through soil or rock on its way to a river is chemically modified during transit, generally by addition of soluble and colloidal substances washed out of the ground. Some substances are removed from the water for example, river water often contains less lead than rainwater one mechanism of removal is uptake by soil. 

River waters carry both dissolved and suspended substances to the sea. The concentrations and absolute fluxes vary tremendously. The suspended solids load is largely a function of the flow in the river, which influences the degree of turbulence and thus the extent to which solids are held in suspension and resuspended from the bed, once deposited. Table 3 shows a comparison of average riverine suspended particulate 

In slow-moving water bodies such as lakes and ocean basins, suspended solids falling to the bottom produce a well-stratified layer of bottom sediment. This is stratified in terms of age with the oldest sediment at the bottom (where when suitably pressurised in can form rock) and the 

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