Influence of hydrologic regime and vegetation on phosphorus retention in Everglades stormwater treatment area wetlands

Abstract

Abstract:The Florida (USA) Everglades ecosystem has been impacted due to increased loading of nutrients, in particular phosphorus (P), primarily from adjacent agricultural areas. Consequently, restoration measures involve the establishment of stormwater treatment areas (STAs) comprising a series of constructed wetlands. A series of mesocosms were established at the inflow of the Everglades Nutrient Removal Project wetland, the first such STA constructed. These mesocosms were designed to mimic STAs, as they operated as flow-through systems and were packed with native soil. The objective of the study was to determine the effects of vegetation and hydrologic fluctuations on P retention/release by the wetland soil and on effluent water quality. Four treatment combinations consisted of continuously flooded with emergents (Typha), intermittently flooded with emergents, continuously flooded with no emergents, and intermittently flooded with no emergents. Intermittently flooded treatments underwent two 1 month drawdown events during the year. Soils were collected to determine the various pools of P and surface water samples were collected twice weekly to determine mass P flux in and out of the mesocosms. Results showed that the majority of the P was stored in the calcium-and magnesium-bound fraction, as well as the refractory pool in the soil. Approximately 91% of the inflow soluble reactive P (SRP) mass was retained within the mesocosms for the continuously flooded treatment, and 80% was retained in the treatments subjected to periodic drawdown events, regardless of vegetation type. There was a net annual flux of dissolved organic P (DOP) out of the mesocosms for the drawdown treatments, whereas the net reduction in the DOP concentrations for the continuously flooded treatments was just 17%. These results demonstrate that, although these wetland systems perform well in reducing surface water SRP, additional research may need to focus on improving the reduction of DOP in order to reduce further the P loads to the nutrient-sensitive Everglades system.

The role of periphyton in phosphorus retention in shallow lakes with different trophic status, China

“…Phosphorus in periphyton mats provides the best metric for detecting phosphorus enrichment in freshwater, which is consistent with the rapid uptake of labile phosphorus from the water column by both biotic and abiotic components of the periphyton detected in radioisotope tracing studies (Scinto and Reddy, 2003). Yet previous studies have reported large variations in the phosphorus removal efficiency of periphyton across space and time (e.g., Vermaat et al, 2000;White et al, 2004;Jakub et al, 2010;Derrick, 2014 water quality function of periphyton, it is necessary to thoroughly understand the various components of and mechanisms involved in phosphorus cycling. Nanhu, Donghu, Niuchaohu, and Liangzihu are four typical shallow lakes with different trophic status in Wuhan City, Hubei province, China.…”

Controls of Suspended Sediment Concentration, Nutrient Content, and Transport in a Subtropical Wetland

“…These vegetation-induced changes can result in lower concentrations of suspended sediment (Braskerud 2001;Leonard and Reed 2002), greater sediment deposition rates , or decreased resuspension of sediments in densely vegetated portions of wetlands (Braskerud 2001). These dynamics of suspended sediment also are important for controlling phosphorus (P) cycling and transport in aquatic ecosystems (Fox 1993;Froelich 1988;Kadlec 1999), with intermediate removal rates of particulate P compared to faster soluble reactive P removal or slower dissolved organic P removal in wetlands (Davis 1981;Farve et al 2004;White et al 2004).…”

Alum Application to Improve Water Quality in a Municipal Wastewater Treatment Wetland

“…On average, alum significantly reduced SRP concentrations to three times lower than the controls (no alum). There was 40% lower DOP concentrations compared with the controls demonstrating that alum caused flocculation of dissolved organic P compounds, which are generally the most difficult forms of P to remove in a treatment wetland (White et al, 2004). There was a similar trend seen for the TDN, which include ammonium (∼5%) and DON (∼95%), with greater removal of DON fraction with alum dosing.…”