ARS | Publication request: PHOSPHORUS DYNAMICS IN A FRESHWATER IN-STREAM WETLAND: EXCHANGE BETWEEN SEDIMENTS AND WATER COLUMN

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2001
Publication Date: N/A

Technical Abstract: Stream water dissolved phosphorus (DP) concentrations are influenced by exchange reactions between wetland sediments and the water column. Wetlands can act either as a DP sink or a source depending upon the direction of this exchange. We examined the exchange of DP between sediment pore water and the water column to determine the DP sink/source role of a North Carolina Coastal Plain in-stream wetland. Water column and sediment pore water DP concentrations were measured using a passive sampler and the data used to determine DP diffusional fluxes. Sediment DP sorption characteristics were determined using isotherms and this data used to calculate equilibrium P concentration (EPC) values. The DP diffusional flux values in the in-steam wetland ranged from -2.5 to +40.6 mg DP m**2 d indicating variable directions in the DP flux between sediments and the water column. The DP concentrations in the water column ranged between 5 to 190 ug/L while the sediment EPC values ranged between 2.2 to 31.9 ug/g. Comparison of DP concentrations in the water column with sediment EPC values also indicated a variable direction in the DP exchange gradient. Our data imply that this wetland can serve both as a DP sink and a source to the stream.