Enrichment Gradients in WCA-2A and Northern WCA-3A: Water, Soil, Plant Biomass, and Nutrient Storage Responses

Increases in cation (e.g., Ca2+, Na+, and Mg2+) and anion (e.g., Cl? and NO? 3) concentrations have been documented throughout the greater Everglades ecosystem (SFWMD 2004, 2005, 2006). In particular, concerns have been raised that elevated calcium (Ca) and sodium (Na) have altered the historic distribution of algal populations (e.g., the relationship between diatom-dominated assemblages and the calcareous periphyton mats; see Chap. 12). Additionally, increased levels of heavy metals and pesticides have been found near input structures, and gradients of these chemicals have developed in portions of the Everglades (Barber 2003; SFWMD 2004, 2005, 2006).

In this chapter we will:

• 1. Detail the methods used for water, soil, and plant elemental analyses reported in this volume as well as provide data quality objectives and method detection limits for parameters measured in the laboratory by the Duke University Wetland Center (DUWC).

• 2. Provide a summary of nutrients and ion gradients in water that were measured by DUWC personnel from 1990 to 2003 in WCA-2A and 1998-2002 in WCA-3A.

• 3. Assess P concentrations in soils along nutrient gradients and present a historical trend analysis.

• 4. Address the problem of efflux of P from enriched soils along the WCA-2A nutrient gradient.

• 5. Present gradient trends for Hg and some trace metals in WCA-2A.

• 6. Quantify the changes in plant biomass and nutrient storage along enrichment gradients.