Long-Term Phosphorus Assimilative Capacity (PAC) in the Everglades
Wetlands have been shown to have some capacity to retain and store phosphorus, although it has been clearly demonstrated their efficiency is reduced as P loads increase (Qian and Richardson 1997b; Richardson and Qian 1999). Peatlands have a lower capacity to retain P than mineral-based wetlands (Richardson 1985, 1999). Nutrient storage capacity, often a design feature of constructed wetlands, is defined as the total mass per unit area that can be retained permanently by the system. However, high P-loading levels may result in significant ecosystem changes (e.g., altered community structure and diversity as well as increased productivity) and increases in downstream P and N output concentrations (Richardson et al. 1997a; Richardson and Qian 1999). One key question concerns the ability of wetlands like the Everglades to assimilate and store P without causing significant changes in the flora and fauna within the ecosystem. This chapter presents an updated version of our earlier P assimilative capacity analysis (Qian and Richardson 1997b; Richardson and Qian 1999) and relates our phosphorus assimilative capacity (PAC) concept with current Stormwater Treatment Area (STA) P loadings and release concentrations.
KeywordsFreshwater Wetland Plant Community Structure Assimilative Capacity Output Concentration Piecewise Linear Model
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