See more from this Session: General Wetland Soils: II (Includes Graduate Student Competition)
Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level
Stormwater Treatment Areas of the Everglades were developed to treat agricultural discharge from the Everglades Agricultural Area. In order to assess the P status of the STAs, we measured different labile and non-labile forms of P to determine the soil allocation of retained P in the ecosystem. Multiple cells of two STAs (STA-5 and 6) were sampled and soil fractionated into labile, Fe-Al bound, Ca-Mg bound, humic-fulvic acid, and residual P pools.. Total P was an average of 53% higher for STA-5 than STA-6. STA-5 had 314, 17, 55, 58, and 77% higher P than STA-6 for KCl, NaOH-Pi, NaOH-Po, HCl-Pi, and residual fractions, respectively. The labile P fraction (KCl-extractable) was low for both STAs, averaging less than 1 mg P/kg. The NaOH-Pi fraction averaged 51 mg P/kg, and overall had the 2nd lowest P concentration of all fractions. An average of 154 mg P/kg was found in the humic-fulvic acid fraction, while the HCl-Pi pool contained 108 mg P/kg. Residual P contains P that is stable and somewhat resistant to decomposition, and this pool contained an average of 68 mg P/kg. STA-5 showed higher P concentrations in both labile and non-labile pools than STA-6, probably because of higher historic P loading which increased total P. The similar percentage increase of P in STA-5 compared to STA-6 suggests that P loading only increased the concentrations of the fractions but not the distribution of P among the fractions. Cells closer to inflow structures generally differed from cells near the outflows, through higher P concentrations in most fractions near inflow points.