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This article in JEQ

  1. Vol. 32 No. 4, p. 1365-1374
     
    Received: May 10, 2002


    * Corresponding author(s): jacinthe.1@osu.edu
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doi:10.2134/jeq2003.1365

Dissolved Organic Carbon Dynamics in a Riparian Aquifer

  1. P.-A. Jacinthe *a,
  2. P. M. Groffmanb and
  3. A. J. Goldc
  1. a School of Natural Resources, 2021 Coffey Road, 210 Kottman Hall, Ohio State Univ., Columbus, OH 43210
    b Inst. of Ecosystem Studies, Millbrook, NY 12545
    c Dep. of Natural Resources Science, Univ. of Rhode Island, Kingston, RI 02881

Abstract

The capacity of riparian soils to remove nitrate (NO 3) from ground water is well established, but the effects of ground water NO 3-enrichment on C dynamics are not well studied. We incubated horizontal cores of aquifer material extracted from beneath moderately well-drained (MWD) and poorly drained (PD) soils in a riparian forest in Rhode Island, USA for 132 d, and dosed (flow rate, 170 mL d−1; dissolved O2, 2 in PD and 5 mg L−1 in MWD cores) with ground water amended with either Br, Br + NO 3 (10 mg N L−1), or Br + NO 3 + DOC (20 mg C L−1). The DOC was extracted from forest floor material and added during the first 56 d of the experiment. Addition of NO 3 had limited effect on CO2 production while DOC amendment had a significant effect in the PD but not in the MWD mesocosms. Total CO2 production (mg CO2–C kg−1 soil) was 6.3, 7.0, and 10.1 in the PD and 3.6, 4.0, and 4.5 in the MWD cores amended with Br, Br + NO 3, and Br + NO 3 + DOC, respectively. Carbon balance (Cbal = DOCin − (DOCout + CO2–C) showed a net C retention of 8.0 mg C kg−1 soil in the DOC-amended MWD cores (equivalent to 50% of the DOC added), and a net C loss of 8.3 mg C kg−1 soil in similarly treated PD cores. The lack of C retention in the PD cores was ascribed to reductive dissolution of minerals implicated in DOC sorption. These findings underscore that there is marked variation in C dynamics in riparian aquifers that has the potential to influence the fate of NO3 and DOC in the landscape.

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Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.32:1365–1374.