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The influence of land-use and seasons on SOM distribution in headwaters of a central Ohio watershed
  • Ozeas Costa Jr,
  • John Volk
Ozeas Costa Jr
The Ohio State University

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John Volk
University of Nevada at Reno
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Soil organic matter (SOM), the accumulated, decaying debris of biota living on or in the soil, represents the largest of the active terrestrial C pools, holding about 1500 Pg C to a depth of 1 m. In aquatic ecosystems, SOM is a storehouse of inorganic nutrients which, after mineralization, are released to the stream and used by planktonic and benthic microorganisms. Here we present the results of a study designed to elucidate the controls on the spatial and temporal variations of the SOM distribution along the Clear Fork River, which drains a mixed urban-agricultural landscape in north-central Ohio. Fluvial bed sediments were sampled monthly (March to October) in eight stations along the river. Organic matter (OM) and carbonate content were determined by loss-on-ignition (LOI). Sediments from all stations were analyzed in triplicate to account for intrasample variation and to provide a measure of precision. Textural analysis was also performed in all samples. Results show OM content varying between 14 and 109 g kg-1, with highest values observed during spring, and lower values during summer. Sediments from stations where the stream flow is high generally presented lower OM concentration. In addition, stations located within urban landscapes presented the highest OM concentrations.