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Nutrient profiles in the everglades: examination along the eutrophication gradient
P Vaithiyanathan1, C J Richardson
1Duke University Wetland Center, Loxahatchee, FL 33470, USA.
The Science of the Total Environment
|November 14, 1997
Summary
Agricultural runoff significantly increased soil phosphorus in the Everglades, shifting nutrient limitation from phosphorus to nitrogen in downstream waters. Organic phosphorus dominates soil P due to wetland plant uptake.
Area of Science:
- Environmental Science
- Ecology
- Biogeochemistry
Background:
- Agricultural runoff introduces excess nutrients into sensitive wetland ecosystems.
- Understanding nutrient cycling is crucial for managing eutrophication in the Everglades.
Purpose of the Study:
- To investigate nutrient concentration profiles in water and soil along an Everglades eutrophication gradient.
- To determine the impact of agricultural runoff on phosphorus and nitrogen dynamics.
Main Methods:
- Analysis of nutrient concentrations (TP, TDP, PO4-P, DIN) in surface water, soil, and pore water.
- Use of 210Pb dating to assess soil phosphorus accumulation rates.
- Evaluation of molar ratios (DIN:DIP) to infer nutrient limitation.
Main Results:
- Phosphorus concentrations decreased exponentially downstream from agricultural inflow points.
- Soil total phosphorus (TP) increased three- to four-fold, with elevated pore water PO4-P.
- Nutrient limitation potentially shifted from phosphorus to nitrogen along the gradient.
- Soil phosphorus accumulation rates correlated with the installation of inflow structures.
Conclusions:
- Agricultural drainage significantly alters phosphorus cycling and soil P concentrations in the Everglades.
- Organic phosphorus is the dominant form in soils, primarily removed by biotic uptake.
- Calcium-bound phosphorus represents a major inorganic P storage mechanism in Everglades soils.