Water Resources Research Act Program

Details for Project ID 2007MD148B

Assessing the role of road salt run-off on the critical ecological interactions that regulate carbon processing in small, headwater streams in the Chesapeake Bay watershed

Institute: Maryland
Year Established: 2007 Start Date: 2007-03-01 End Date: 2009-03-01
Total Federal Funds: $23,663 Total Non-Federal Funds: $47,419

Principal Investigators: Christopher Swan

Project Summary: Small streams constitute a large majority of the stream miles in a drainage basin, accentuating the link these reaches have to the landscape. As such, the ecological condition of streams and rivers reflect human disturbance in the watershed. The consequence for society is the degradation of water quality as habitat is modified, reducing the capacity of the biota to properly mediate natural rates of nutrient cycling (e.g., carbon mineralization, denitrification). Recently, researchers have discovered that streams draining human-dominated landscapes can experience enhanced loading of road salt deicer. Elevated levels of chloride are reported to increase with impervious surface cover, reaching levels toxic to freshwater life. The potential for anthropogenic salinization to alter ecosystem processes performed by streams, specifically carbon processing, is largely unknown. Biological processing of the seasonal input of detritus from riparian forests may very well suffer from chloride loading. There exist strong microbial and invertebrate contributions to the decay of this material, and experimentation has demonstrated that inhibiting these components of the community results in drastic changes to export of both carbon and nitrogen downstream. Thus, any abiotic factor altering either the microbial or invertebrate community is likely to disrupt decomposition of organic matter and carbon processing in these systems. I propose a series of experiments to learn how an increase in road deicer, specifically NaCl, alters water quality. Given the energetic reliance of forested stream food webs on riparian-derived detritus (e.g., senesced leaf litter, wood), and the subsequent feed-back the microbial and invertebrate community has on mineralization of this material, I will focus on the effects of rising salt levels on carbon processing in small, headwater streams.