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Fig. 7.1 Schematic representation of stabilization of heavy metals by wetland plants

7.5 Wetland Ecosystems: Introduction and Importance

Wetlands are areas where water is the primary factor controlling the environment
and the associated life forms. In these regions, saturation with water determines the
soil development character and the growth of flora and fauna living in the area.
These are transitional zones that occupy an in-between position flanked by dry land
and open water. Thus, wetlands may support both aquatic and terrestrial species as
well as acting as “Kidney of Nature” (USEPA 1995). In broader sense, wetlands are
“areas of marsh, fen, peat-land or water, whether natural or artificial, permanent or
temporary, with water that is static or flowing, fresh, brackish or salt, including
areas of marine water the depth of which at low tide does not exceed 6 m. Wetlands
may also incorporate riparian and coastal zones adjacent to the wetlands, and
islands or bodies of marine water deeper than six meters at low tide lying within
the wetlands” (Article 1.1 and 2.1 of Ramsar Convention on wetlands). Found all
over the world except Antarctica, wetlands vary widely because of diversity in
topography, climate, soils, hydrology and water chemistry, vegetation, and other
factors, including human interference. It has been estimated that about 570 million
2
hectares (5.7 million km )—roughly 6 % of the Earth’s land surface is wetland.
Among this, 2 % are lakes, 15 % floodplains, 20 % swamps, 26 % fens, and 30 %
bogs (Mitsch and Gosselink 2000). Wetlands are some of the most productive and
dynamic habitats in the world. Long regarded as wastelands, wetlands are now
regarded as vital component in the landscape that affords plentiful of valuable
services for the environment, wildlife, and people (USEPA 2001). Wetlands can be
regarded as biological supermarkets due to species richness and diversity and their
functions are basically the interrelations between different physicochemical and
biological entities present in the area. These functions include flood control,
groundwater replenishment, nutrient retention and export, water purification,