Wetlands area, global

Wetland areas with organic soils were excluded using the global database of Matthews (1989) as described by Matthews and Fung (1987) and in the text. Water storage capacities were derived from the difference between water contents determined in the laboratory on mineral soil cores subject to 10 and 100 or 10 and 1500 bPa of applied suction. From left to right, the mineral soil texture classes of Zobler (1986)/Cosby ctni (1984)(abbreviation, percentages of sand silt clay) are coarse/loamy sand (LS, 82 12 6), medium fme/sandy clay loam (SCL, 58 15 27), medium coarse/sandy loam (SL, 58 ,52 10), and medium/loam (L,43 39 18). 

The work performed in Kejimkujik Park, Nova Scotia demonstrates that substantial mercury bioaccumulation can occur in remote areas where no abnormal sources of mercury exist. The mass balance preformed at BDW Lake in Kejimkujik Park, showed that movement of atmospheric mercury from the terrestrial catchment to wetland areas is the primary source of methyl mercury to the lake. Mercury volatilization was found to be an important process in this basin with annual volatilization equaling 46% of the mercury deposited by precipitation over the entire lake basin. This paper demonstrates that mercury speciation must be known to reliably predict the effect of anthropogenic influences on a regional and global scale. 

Figure 6.1. Ecosystem area and soil carbon content to 3-m depth. Lower Panel Global areal extent of major ecosystems, transformed by land use in yellow, untransformed in purple. Data from Hassan et al. (2005) except for Mediterranean-climate ecosystems transformation impact is from Myers et al. (2000) and ocean surface area is from Hassan et al. (2005). Upper Panel Total C stores in plant biomass, soil, yedoma/permafrost. D, deserts G S(tr), tropical grasslands and savannas G(te), temperate grasslands ME, Mediterranean ecosystems F(tr), tropical forests F(te), temperate forests F(b), boreal forests T, tundra FW, freshwater lakes and wetlands C, croplands O, oceans. Data are from Sabine et al. (2004), except C content of yedoma permafrost and permafrost (hght blue columns, left and right, respectively Zimov et al., 2006), and ocean organic C content (dissolved plus particulate organic Denman et al., 2007). This figure considers soil C to 3-m depth (Jobbagy and Jackson, 2000). Approximate carbon content of the atmosphere is indicated by the dotted lines for last glacial maximum (LGM), pre-industrial (P-IND) and current (about 2000). Reprinted from Fischlin et al. (2007) in IPCC (2007). See color insert.

Matthews E. and Fung I. (1987) Methane emission from natural wetlands global distribution, area, and environmental characteristics of sources. Global Biogeochem. Cycles 1, 61-86. 

Globally, extensive areas of peatlands and wetlands have been drained and converted into agricultural lands. Drainage of organic matter-rich soils accelerated the decomposition process and emission of carbon dioxide. Many peatlands that have accumulated organic matter for centuries... 

The coastal wetlands are currently experiencing increases in water level projected in the near future for other coastal areas as a result of global warming and associated increase in global sea level. 

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