The Effects of Land Use on the Dynamics of Organic Carbon, Nitrogen, and Phosphorus Exported from Coastal Watersheds <p> HR: <span class="hr"> 14:15h<br></span> AN: <span class="an"> B53A-04 <a href="../absbook/sm05_B53A.html">[Abstracts]</a><br></span> TI: <span class="ti"> The Effects of Land Use on the Dynamics of Organic Carbon, Nitrogen, and Phosphorus Exported from Coastal Watersheds <br></span> AU: <span class="au"> * Kaushal, S S<br></span> EM: <span class="em"> kaushal@al.umces.edu<br></span> AF: <span class="af"> University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532-2307 United States <br></span> AU: <span class="au"> Groffman, P M<br></span> EM: <span class="em"> GroffmanP@ecostudies.org<br></span> AF: <span class="af"> Institute of Ecosystem Studies, Box AB Route 44A, Millbrook, NY 12545 United States <br></span> AU: <span class="au"> Findlay, S E<br></span> EM: <span class="em"> FindlayS@ecostudies.org<br></span> AF: <span class="af"> Institute of Ecosystem Studies, Box AB Route 44A, Millbrook, NY 12545 United States <br></span> AU: <span class="au"> Fischer, D T<br></span> EM: <span class="em"> FischerD@ecostudies.org<br></span> AF: <span class="af"> Institute of Ecosystem Studies, Box AB Route 44A, Millbrook, NY 12545 United States <br></span> AB: <span class="ab"> We investigated the relationship between changes in land use and the abundance and metabolism of organic C, N, and P in coastal streams of the Chesapeake Bay watershed. Concentrations of inorganic N and P declined along a gradient of urbanization whereas concentrations of organic C, N, and P increased in streams. Storm sewers appeared to be a substantial contributor of inorganic nutrients to streams, but showed a lower relative contribution of organic nutrients suggesting the importance of in-stream generation in addition to external sources. Laboratory incubations indicated seasonal changes in the bioavailability of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), but temporal patterns in the metabolism of both DOC and DON differed based on land use. The bioavailability of DOC peaked sharply during spring months in forested watersheds whereas it peaked later during summer months in suburban and urban watersheds. Bioavailability of DON in streams increased with urbanization, and concentrations of bioavailable DON in developed areas sometimes exceeded concentrations of inorganic nitrogen in undeveloped forested streams. Across gradients of urbanization, shifts in the relative abundance of organic nutrients versus inorganic nutrients coincided with variations in the enzymatic activities of heterotrophic microbial communities in stream sediments. Changes in land use may lead to large increases in the amount and reactivity of DOC, DON, and DOP exported from watersheds and organic nutrients may need to be regulated for the maintenance of water quality. <br></span> UR: <span class="ur"> <a href='http://www.al.umces.edu'>http://www.al.umces.edu</a> <br></span> DE: <span class="de"> 0400 Biogeosciences<br></span> SC: <span class="sc"> Biogeosciences [B]<br></span> MN: <span class="mn"> 2005 Joint Assembly<br></span></p></body></html>