Classification and physical attributes of wetlands and their interaction with pollutant inputs

Wetlands are areas of land where the water table is usually close to the surface, or the land is intermittently or permanently covered by water. Wetlands are an attractive landscape feature and they provide a habitat for native wildlife as well as a potential source of reusable water. There may also be the potential for sporting and recreational facilities, and agriculture and aquaculture farming within artificially managed wetland systems. These factors lead to wetlands being considered as some of the most precious environments on Earth. Wetlands are classified according to their depth, period of inundation and salinity. The role of wetlands as biological filters to remove or convert contaminants from the open sea or from the river input is of prime importance. Figure 1 gives an overviewof the physical processes in a typical marinewetland. This chapter tries to define inmore detailwhat awetland is and howit can be classified. Many possible classifications exist in the literature.