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Global Biogeochemical Cycles

Amounts, isotopic character, and ages of organic and inorganic carbon exported from rivers to ocean margins: 2. Assessment of natural and anthropogenic controls

Authors

  • Katie Hossler,

    Corresponding author
    1. Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
    • Corresponding author: K. Hossler, Aquatic Biogeochemistry Laboratory, Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 1314 Kinnear Rd., Columbus, OH 43212-1156, USA. (hossler.3@osu.edu)

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  • James E. Bauer

    1. Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
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Abstract

[1] Riverine exports of carbon (C) and organic matter (OM) are regulated by a variety of natural and anthropogenic factors. Understanding the relationships between these various factors and C and OM exports can help to constrain global C budgets and allow assessment of current and future anthropogenic impacts on both riverine and global C cycles. We quantified the effects of multiple natural and anthropogenic controls on riverine export fluxes and compositions of particulate organic C, dissolved organic C, and dissolved inorganic C for a regional group of eight rivers in the northeastern U.S. Potential controls related to hydrogeomorphology and regional climate, soil order, soil texture, bedrock lithology, land use, and anthropogenic factors were analyzed individually, collectively, and at scales of both local and regional influence. Factors related to hydrogeomorphology and climate, followed in importance by land use and anthropogenic factors, exhibited the strongest impacts on riverine C exports and compositions, particularly at smaller localized scales. The effects of hydrogeomorphology and climate were primarily related to volumetric flow, which resulted in greater exports of terrestrial and total C. Principal anthropogenic factors included impacts of wastewater treatment plants (WWTPs) and river impoundments. The presence of WWTPs as well as anthropogenic use of carbonate-based materials (e.g., limestone) may have substantially increased riverine C exports, particularly fossil C exports, in the study region. The presence of nuclear power plants in the associated watersheds is also discussed because of the potential for anthropogenic 14C inputs and subsequent biasing of aquatic C studies utilizing natural abundance 14C.

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