Water Resources Research Act Program

Details for Project ID 2006MD116B

Investigation of the effects of increased salinization from deicer use on increased transport of nitrogen in streams of the Chesapeake Bay Watershed

Institute: Maryland
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $49,998 Total Non-Federal Funds: $117,968

Principal Investigators: Sujay Kaushal, Keith Eshleman, Gary Fisher, Peter Groffman, Paul Mayer, Ray Morgan

Project Summary: Salinity is now increasing in many streams across Maryland toward thresholds beyond which significant changes in ecological communities and ecosystem functions may be expected due to increased deicer use on roadways, fertilizer applications, operation of water softeners, and discharges from septic systems and wastewater treatment plants. As a result of large increases in suburban and urban growth over decades, concentrations of chloride, a common anion of many salts, have now exceeded the limit of 250 mg/L established by the U.S. EPA for chronic toxicity to freshwater life in many streams of the Baltimore metropolitan area. The ranges and extreme fluctuations in salinity observed in Maryland streams have been shown to inhibit denitrification, a microbial process that is critical for the removal of nitrate and maintenance of water quality in many streams. We propose to study the effects of increased salinization on impairment of in-stream processing and removal of nitrogen via denitrification in streams, and subsequent implications for the increased downstream transport of nitrogen to coastal ecosystems. The objectives of the study are to (1) investigate the effects of increased salinity on rates of nitrogen removal through denitrification in different stream features (debris dams, and sediments from pools, riffles, and gravel bars) in streams across Maryland surrounded by different land use and geomorphic setting and (2) characterize seasonal changes in levels and sources of salinity in streams by measuring concentrations and ratios of Na, Cl, and K ions. Denitrification potential will be measured in stream features (debris dams, and sediments from pools, riffles, and gravel bars) under ambient conditions in streams near roadways and nearby forested control sites and following amendments with road salt. The denitrification measurements will be conducted twice per year in the Appalachian Mountains, Piedmont, and Baltimore metropolitan area during summer months and winter months. Water samples from all sites will be collected monthly for measurement of concentrations and ratios of Na, Cl, and K ions as part of existing studies that are already maintained by the UMCES Appalachian Lab, Maryland Biological Stream Survey, USGS, Institute of Ecosystem Studies, NSF supported Baltimore LTER site, and EPA. The proposed project builds strongly on existing research within Maryland and provides an estimate of denitrification in stream features in streams across regions experiencing dramatic changes in land use and the potential alteration of nitrogen cycling. The work will specifically identify thresholds for critical ecosystem processes related to downstream nitrogen transport and water quality. The project also has the potential to build on the Maryland Biological Stream Survey for future research because broader scale characterizations of baseline biogeochemical processes critical to water quality and expectations on how they may be altered by land use change are rare in the literature.