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Mesocosm experiments to assess factors affecting phosphorus retention and release in an extended Wisconsin wetland

Water-Resources Investigations Report 97-4272

Prepared in cooperation with the Wisconsin Department of Natural Resources
By:
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Abstract

Phosphorus retention by wetland sediments and vegetation was investigated in Jackson Creek wetland, an extension of an existing prairie marsh in southeastern Wisconsin. The extended wetland construction was undertaken in 1992-93 to help reduce the phosphorus loading to a downstream eutrophic lake. Two approaches were used to study potential and actual phosphorus retention in the system. Mesocosm experiments of 20-40 days duration indicated that retention of total and dissolved reactive phosphorus in mesocosm cells containing macrophytes and/or sediments was reduced by factors of 2-20 relative to cells containing only water or a copper algicide to suppress metabolic activity. In contrast to the nutrient trapping function, these results show a potential for net phosphorus release that can be associated with increased biological richness. Measurements of water flow and nutrient loads at the wetland's inflow and outflow points demonstrated 9-39% net uptake of phosphorus on an annual scale but frequent occurrences of net phosphorus release over shorter (one-month) time scales. These episodes of release are most likely during the summer months. Thus, the wetland role in phosphorus cycling is not one of a true source or sink, although the annual budget data alone suggest substantial net retention. Effective management of the wetland for its nutrient trapping potential can be hindered by this oversimplification. The system is instead subject to relatively short-term alternation between net import and export. The periodic phosphorus export, although representing a small fraction of net annual import, could be critical for growth of macrophyte and algal communities downstream.

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Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Mesocosm experiments to assess factors affecting phosphorus retention and release in an extended Wisconsin wetland
Series title:
Water-Resources Investigations Report
Series number:
97-4272
Year Published:
1997
Language:
English
Publisher:
U.S. Geological Survey
Contributing office(s):
Wisconsin Water Science Center
Description:
vi, 14 p.
Country:
United States
State:
Wisconsin
County:
Walworth County
Other Geospatial:
Delevan Lake, Jackson Creek
Online Only (Y/N):
N
Additional Online Files (Y/N):
N