Environmental Engineering Reference
In-Depth Information
FIGURE 9.3
Satellite image of South Florida, circa 1995, with light outline representing areas sampled: Everglades Agricultural Area (EAA); Arthur R.
Marshall Loxahatchee National Wildlife Refuge (LNWR); Everglades Water Conservation Area 2 (WCA-2); Everglades Water Conservation
Area 3 north of Alligator Alley (WCA-3A); Everglades Water Conservation Area 3 south of Alligator Alley (WCA-3A); the eastern portion of
Big Cypress Swamp National Preserve, and the freshwater portion of Everglades National Park (ENP). Light areas on the east are urban
development. The black line approximates the extent of the historic (pre-1900) Everglades marsh. The Everglades watershed extends north of
Lake Okeechobee.
Sulfur supplies and concentrations have important envi-
ronmental implications for the Everglades. Sulfur is a criti-
cally important driver of MeHg production and exposure
(Benoit et al., 2003). Elevated concentrations of sulfate can
also enhance the supply of phosphorus from wetland soils
to surface waters, and high concentrations of sulfi de may be
toxic to plants (Lamars et al., 1998; Smolders et al., 2006).
As a result, the Comprehensive Everglades Restoration
Plan recommends that sulfate (SO
4
-S) concentrations be
decreased or maintained to concentrations of 1 mg/L or
A logical mechanism to partially explain this spatial pat-
tern in fi sh mercury is DOC. Naturally occurring organic
solutes bind Hg
2
and MeHg (Aiken et al., 2003), likely
reducing bio-availability (Hudson et al., 1994; Driscoll
et al., 1995). The northern Everglades, which are strongly
infl uenced by the EAA storm water have higher concentra-
tions of DOC and are more reactive with Hg than southern
areas of ENP (Figure 9.5; Aiken et al., 2006). Mercury in
mosquitofi sh is correlated with DOC-normalized MeHg but
not total MeHg in surface water (USEPA, 2007b).
