Wednesday, June 6, 2007 - 10:15 AM
218

Inadvertent Water Quality Impacts on Everglades National Park from Upstream Water Management Practices

Joffre Castro, South Florida Natural Resources Center, Everglades National Park, 950 N. Krome Avenue, 3rd Floor, Homestead, FL 33030-4443

Methylmercury concentrations within the Everglades Protection Area have undergone a trend reversal and are presently declining, except in Everglades National Park (ENP).  Existing data from ENP show that methylmercury levels in fish (largemouth bass and sunfish) have increased by as much as 140 percent (largemouth bass) since 1999 at North Prong Creek (near Shark River) and to a lesser extent at the L67 extension canal.  Interestingly, these increases in methymercury do not appear to be related to total mercury increases but to sulfate increases.  In this study, a connection is made between water-quality changes at ENP inflow station  S-333 and ENP’s water-delivery practices.  Every time a different water-delivery plan was implemented, there was a noticeable shift in the concentration of several water-quality constituents, including sulfate.  These plans have altered the marsh’s natural drying-and-wetting cycles by increasing the number and frequency of dry-down events, for example in Water Conservation Area 3.  During the drying season, reduced sulfur (sulfide) from the soil is oxidized and, during the following wetting season, the oxidized sulfur (sulfate) is remobilized into the water column increasing the pool of available sulfate within the optimum range (2 to 10 mg/L) for methylmercury production.

See more of Special Session - Everglades Water Quality: On the Critical Path to Restoration II
See more of Special Sessions

See more of The NABS 55th Annual Meeting