Evolving Human Alteration of the Carbon Cycle: the Watershed Continuum

Thursday, 18 December 2014: 4:00 PM
Sujay Kaushal1, Katie Delaney Newcomb2, Tarmara Newcomer Johnson1, Michael J Pennino1, Rose Marie Smith1, Jake J Beaulieu3, Kenneth Belt4, Melissa Grese1, Joel Blomquist5, Shuiwang Duan6, Stuart Findlay7, Gene Likens7, Paul M Mayer8, Sudhir Murthy9, Ryan Utz10 and Metthea Yepsen6, (1)University of Maryland College Park, College Park, MD, United States, (2)US Forest Service Portland, Portland, OR, United States, (3)Environmental Protection Agency Cincinnati, Cincinnati, OH, United States, (4)US Forest Service Cockeysville, Cockeysville, MD, United States, (5)USGS Maryland/Delaware/District of Columbia Water Science Center, Baltimore, MD, United States, (6)University of Maryland, College Park, MD, United States, (7)Cary Institute of Ecosystem Studies, Millbrook, NY, United States, (8)Environmental Protection Agency Corvallis, Corvallis, OR, United States, (9)DC Water, Washington DC, United States, (10)National Ecological Observatory Network, Boulder, CO, United States
Watersheds experiencing land development are constantly evolving, and their biogeochemical signatures are expected to evolve across both space and time in drainage waters. We investigate how land development influences spatial and temporal evolution of the carbon cycle from small streams to major rivers in the Eastern U.S. Along the watershed continuum, we show that there is spatial evolution in: (1) the amount, chemical form, and bioavailability of carbon; (2) carbon retention/release at the reach scale; and (3) ecosystem metabolism of carbon from headwaters to coastal waters. Over shorter time scales, the interaction between land use and climate variability alters magnitude and frequency of carbon "pulses" in watersheds. Amounts and forms of carbon pulses in agricultural and urban watersheds respond similarly to climate variability due to headwater alteration and loss of ecosystem services to buffer runoff and temperature changes. Over longer time scales, land use change has altered organic carbon concentrations in tidal waters of Chesapeake Bay, and there have been increased bicarbonate alkalinity concentrations in rivers throughout the Eastern U.S. due to human activities. In summary, our analyses indicates that the form and reactivity of carbon have evolved over space and time along the watershed continuum with major implications for downstream ecosystem metabolism, biological oxygen demand, carbon dioxide production, and river alkalinization.