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7 Use of Wetland Plants in Bioaccumulation of Heavy Metals 123

shoreline stabilization and storm protection, sediment and nutrient retention, cli-
mate change mitigation, reservoirs of biodiversity, wetland products, recreation
tourism, and cultural value (Reed 1991). For conservation and wise use of natural
resources of wetlands, the “Convention on Wetlands (Ramsar, Iran, 1971)” is an
intergovernmental treaty adopted on 2 Feb 1971 in the Iranian city of Ramsar,
which is now popularly known as “Ramsar Convention.” More than 1,631 wetlands
have been designated for inclusion in the List of Wetlands of International Impor-
tance, covering around 193,553,062 hectares, involving 162 contracting parties
(source: http://www.ramsar.org, accessed on 30 Aug 2012).
Services provided by the wetland ecosystems are hugely valuable to people
worldwide. It is not possible to measure tangible values of the diverse services
towards the Nature by wetlands. A lot of these services like water purification,
groundwater recharge, or values related to aesthetic and cultural are not instantly
apparent to a wetland. However, the value of these wetlands and their associated
ecosystem services has approximately been estimated at US$14 trillion annually
(Millennium Ecosystem Assessment 2005). Role of wetland biota and their signifi-
cant abilities in removal and/or breakdown of pollutants, xenobiotics, nutrients and
other compounds through detoxification, retention, recovery, and removal help a lot
for the pollution control strategies throughout the world. However, water or soil
quality of the region influences the maximum amount of waste that can be recycled
or immobilized on a sustainable basis (de Groot et al. 2006).

7.6 Restoration of Metal-Contaminated Wetland
by Phytoremediation

Throughout the world, water quality of the wetlands is severely affected by
increasing anthropogenic and industrial activities and untreated waste dumping.
Thus, wetland pollution and degradation is increasingly becoming a major issue
reflecting changes in water quality, quantity, flow rates, and in species composition.
Filling up or drainage or diversion of wetlands for development, farming, and
mosquito control also cause degradation of wetlands. Further, diverse organic and
inorganic contaminants like heavy metals pollution above a limit gradually annihi-
late these important regions.
Runoffs (may be storm water or nonpoint source pollution) usually carry diverse
metals into the wetlands. Wetlands have the potentiality to improve naturally the
water quality, and therefore, wetlands may be used to treat runoff of different
contaminants. Wetlands do provide valuable water quality protection for downstream
rivers, lakes, and estuaries (USEPA 2009b) that signify their importance to protect
and restore such wetland areas. To replicate the functions of filtering pollutants of
wetlands, artificial wetlands like marsh or swamp may be created to restore habitat.
The constructed wetlands are usually constructed in such a way to involve similar
wetland vegetation’s, soils, and their associated microbial assemblages like that of