Bioavailability of dissolved organic carbon across a hillslope chronosequence in the Kuparuk River region,Alaska |
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| Institution: | 1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China;2. College of Resources and Environment, Northwest A&F University, Yangling 712100, China;3. School of Resources and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450045, China;1. Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan 71703, Taiwan, ROC;2. Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan, Taiwan, ROC;3. Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan, ROC;1. Dept. of Inorganic Chemistry, University of Bucharest, 23 Dumbrava Rosie St, Sector 2, Bucharest 020464, Romania;2. Dept. of Physical Chemistry, University of Bucharest, 4-12 Regina Elisabeta Blvd, Sector 3, Bucharest 030018, Romania;3. National Institute of Materials Physics, P.O. Box MG-7, Magurele 077125, Romania;1. Central Soil Salinity Research Institute, Regional Research Station, Lucknow, 226002, India;2. Central Soil Salinity Research Institute, Karnal, 132001,Haryana, India;3. Indian Council of Agricultural Research, New Delhi, 110012, India;4. Department of Geografia, University of València, BlascoIbàñez, 28, 46010-Valencia. Spain;1. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China;2. College of Environment, Hohai University, Nanjing, 210098, China;3. Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK;4. Hydrology Bureau of Jiangxi Province, Nanchang, 330002, China |
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| Abstract: | Dissolved organic matter (DOM) represents an important component of carbon and nutrient cycling in arctic ecosystems. In northern Alaska, DOM production and microbial activity differ among landscapes with varied glaciation histories with lower rates on younger landscapes. In addition, within the region, soil DOM concentrations vary at the scale of hillslope toposequences, with higher concentrations in upslope than streamside positions. However, it is unknown whether variation in DOM production quality among and within landscapes linked to patterns in DOM quality. To answer this question, we conducted a study of DOM biodegradability within and among hillslopes of different landscape age. We examined rates of DOM decomposition and several indices of the quality of water-extracted DOM collected from soils in the summer. A variety of methods indicated that DOM quality generally was consistent across hillslope positions and among landscape ages. For example, DOM fluorescence index, an index of quality for chromophoric DOM, did not vary significantly across all hillslope positions or landscape ages. There were no significant differences among landscape ages or hillslope positions in DOM specific UV absorbance, in rates of DOM mineralization, or in DOM decomposition, indicating that DOM quality was consistent regardless of its source or position along hillslope flow paths. This suggests that despite many potential sources of variation within and among arctic hillslopes linked to differences in vegetation, hydrology, microclimate, and microbial activity, there is little variation in growing-season soil DOM quality. Microbial processing of DOM within arctic hillslopes may lead to a convergence in growing season DOM quality resulting in little spatial variation. Approximately 10–20% of the growing season DOM is labile in tundra soils, slightly higher that the proportion that is labile in arctic rivers during the summer. |
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| Keywords: | Dissolved organic carbon Arctic Decomposition Topography Landscape age |
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