Analysis of wetland total phosphorus retention and watershed structure

Abstract

The relationship between total phosphorus retention, landscape position of wetlands, and surrounding land-use patterns was explored with the goal of identifying easily determined landscape parameters as indicators of a wetland’s role in water quality maintenance. Sediment cores were collected from 14 wetland sites chosen to represent a range of wetland types, wetland position, and surrounding land-use patterns in a small coastal Virginia watershed. Sediment accumulation rates and total phosphorus retention rates were analyzed using¹³⁷Cs dating and acid extraction techniques. Both sediment accumulation rates and total phosphorus retention rates were found to be comparable to previously reported values for similar wetland types. The landscape analysis did not support the hypothesis that total phosphorus retention would vary with landscape setting and/or wetland type. The wetlands sampled may represent landscape parameters too similar to detect any significant differences. Alternatively, the findings may indicate that in small coastal watersheds, most wetlands perform total phosphorus retention functions to the same level. The management implications of this latter conclusion may be that headwater wetlands are particularly important for water quality functions.