Researcher(s)
- Lauren Schechter, Agriculture and Natural Resources, University of Delaware
Faculty Mentor(s)
- Yan Jin, Department of Plant and Soil Sciences, University of Delaware
Abstract
Coastal wetlands act as a buffer between salt and freshwater systems, causing interactions between saline and freshwater that alter the biogeochemical processes of soil and its porewater, including the transport of elements. Wetlands can act as source or sink of Phosphorus based on its interactions with soil matrices. Due to environmental consequences associated with high levels of phosphorus, such as eutrophication, understanding the interface between salt and freshwater in coastal wetlands is important for the protection of the wetland ecosystem. Dissolved phosphorus has been primarily observed as (> 450 nm) size fractions, however this neglects the role of the range of colloidal fractions (~1 -1000 nm) in regards to Phosphorus transport. Given the particularly significant role of wetland soils in P storage and cycling, the dynamics of colloidal P depending on the salinity and flooding events remain a critical knowledge gap. In this study, the overall objective is to investigate Phosphorus concentration in the dissolved (<2.3 nm), natural nanoparticle (NNP, 2.3-100 nm), fine colloid (100-450 nm), and particulate (450-1000 nm) fractions in pore-waters collected from St. Jones Reserve, Delaware. Depending on the salinity and hydrologic conditions, a transect was delineated and multiple piezometers were installed at 30 cm and 120 cm depths in four zones, named S1, S2, S3, and S4. Pore-water samples are collected monthly starting from June 2022. A combination of sequential centrifugation and ultrafiltration set-ups were chosen to differentiate four different size fractions. The size-fractionated Phosphorus concentration was measured using the molybdenum blue method. It was found that at sites S3 and S4, which contained higher levels of salinity, dissolved phosphorus was also at higher concentrations.