Skip to main content
ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #132253
Title: LAND USE AND FLOW REGIME EFFECTS ON PHOSPHORUS CHEMICAL DYNAMICS IN THE FLUVIAL SEDIMENT OF THE WINOOSKI RIVER, VERMONT

Author
item MCDOWELL, R - AGRESEARCH LIMITED
item Sharpley, Andrew
item CHALMERS, A - USGS

Submitted to: Ecological Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2001
Publication Date: 3/20/2002
Citation: MCDOWELL, R.W., SHARPLEY, A.N., CHALMERS, A.T. LAND USE AND FLOW REGIME EFFECTS ON PHOSPHORUS CHEMICAL DYNAMICS IN THE FLUVIAL SEDIMENT OF THE WINOOSKI RIVER, VERMONT. ECOLOGICAL ENGINEERING. 2002. V. 18. P. 477-487.

Interpretive Summary: Phosphorus is a key element in the eutrophication of freshwaters. Since the late 19th century inputs of phosphorus into Lake Champlain in the northeastern U.S.A. have increased four-fold corresponding with accelerated plant growth and associated water quality problems. The phosphorus comes from anthropogenic inputs in the form of municipal and industrial wastewater, urban and agricultural runoff and phosphate based detergents. Since the implementation of the 1972 US Clean Water Act, a ban on P-based detergents, the construction of P-removal facilities, municipal and industrial treatment plants and controls on agricultural runoff have decreased the amount of phosphorus entering the Lake. However, algal growth is still at levels that cause poor water quality, which has been attributed to the release of phosphorus stored in deposited river and lake sediments. Clearly, an understanding of the transportation, storage and cycling of phosphorus within the Lake Champlain watershed is required in order to decrease the phosphorus loading further. We found that sediment phosphorus release to waters of the Winooski River, VT (the largest tributary to Lake Champlain), was greater in parts of the river draining agricultural than forested land. Although land use and flow regime determined whether Winooski River sediments acted as a sink or source of phosphorus to Lake Champlain, long-term remedial strategies for the watershed should continue to focus on decreasing phosphorus losses in agricultural and urban runoff.

Technical Abstract: In the last century, four-fold increase in phosphorus (P) loadings to Lake Champlain, Vermont have led to nuisance levels of algal growth occurring more often. Although point and nonpoint source load reduction strategies have helped decrease P inputs, eutrophication still occurs. To better understand the transport, storage, and cycling of P within the lakes watershed, we examined the bioavailability of and processes controlling sediment P release to waters of the Winooski River, VT; the largest tributary to Lake Champlain. Iron-oxide strip P (algal-available P) of the river sediments adjacent to agricultural land (3.6 mg/kg) was greater (P<0.05) than adjacent to forested land (2.4 mg/kg). When compared among similar flow regimes, impoundment (731 mg/kg) and reservoir sediments (803 mg kg-1) had greater total P concentrations than river sediment (462 mg/kg). This was attributed to more fines (< 63 um) in impoundments and reservoirs (64%) than in river sediments (33%), which also decreased the ability of impoundment sediments to release P to solution and thereby be a sink for P. Although land use and flow regime influenced if Winooski River sediments acted as a sink or source of P to Lake Champlain, long-term remedial strategies for the watershed should continue to focus on decreasing P losses in agricultural and urban runoff.