Seasonal and Spatial Patterns of Surface Water in Large-Scale Treatment Wetlands with Different Vegetation Communities

Hu, J., Vardanyan, L., Villapando, O., Bhomia, R., Inglett, P. W., Li, X., Feng, G., & Reddy, K. R. (2021). Seasonal and Spatial Patterns of Surface Water in Large-Scale Treatment Wetlands with Different Vegetation Communities. ASA, CSSA, SSSA International Annual Meeting. Salt Lake City, UT: ASA-CSSA-SSSA.

Abstract

The Stormwater Treatment Areas (STAs) were built strategically to remove excess phosphorus (P) and protect the natural Everglades areas. Emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV) are two dominant vegetation communities in STAs. The objective of this study is to compare the seasonal changes and spatial patterns of surface water physicochemical properties within two parallel flow-ways (FWs) in STA-2, predominantly colonized by EAV and SAV, respectively. Surface water samples were collected four times between September 2016 and March 2018 (two times in Fall and two times in Spring) from three stations near inflow, middle flow, and outflow of each FW. Short-term monitoring and assessment of selected biogeochemical parameters, including P and nitrogen (N) and their forms in the water column, showed distinct differences in internal spatial gradient and seasonal patterns of P and N, and associated elements in EAV and SAV flow-ways. Total P concentrations showed a distinct gradient along the flow-path in both FWs, with soluble reactive P removed highly efficiently from the water column compared to dissolved organic P and particulate P. Total nitrogen, which mainly consisted of dissolved organic N and particulate organic N, did not show a consistent trend with the concentration generally decreased in Fall and increased or did not change in Spring along the flow-path. The results of partial squares structural equation modeling indicate that seasonal variation in surface water quality was more evident in EAV systems, while SAV systems were susceptible to extreme events such as hurricane. A hybrid system with both EAV and SAV could be an option to maintain stability and high efficiency in removing nutrients and protect the downstream ecosystems.