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USGS · 70018184

Re-evaluation of colorimetric Cl- data from natural waters with DOC

S. A. Norton·M.J. Handlet·J. S. Kahl·N.E. Peters
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Abstract

Colorimetric Cl- data from natural solutions that contain dissolved organic carbon (DOC) may be biased high. We evaluated aquatic Cl- concentrations in ecosystem compartments at the Bear Brook Watershed, Maine, and from lakes in Maine, using ion chromatography and colorimetry. DOC imparts a positive interference on colorimetric Cl- results proportional to DOC concentrations at approximately 0.8 ??eq Cl-/L per mg DOC/L. The interference is not a function of Cl- concentration. The resulting bias in concentrations of Cl- may be 50% or more of typical environmental values for Cl- in areas remote from atmospheric deposition of marine aerosols. Such biased data in the literature appear to have led to spurious conclusions about recycling of Cl- by forests, the usefulness of Cl- as a conservative tracer in watershed studies, and calculations of elemental budgets, ion balance, charge density of DOC, and dry deposition factors.

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S. A. Norton, M.J. Handlet, J. S. Kahl, N.E. Peters. 1996. Re-evaluation of colorimetric Cl- data from natural waters with DOC. https://doi.org/10.1007/bf00666264

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