Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Pamela J. Edwards; J. David Helvey
    Date: 1991
    Source: Journal of Environmental Quality. 20(1): 250-255.
    Publication Series: Scientific Journal (JRNL)
    Station: Northern Research Station
    PDF: Download Publication  (176.0 KB)


    The electrical conductivity of stream water draining from an unmanaged and undisturbed control watershed has been increasing rather steadily, about 0.03 mS m-1 yr-1, since 1971. During this period, NO3 and Ca2+ concentrations increased and were shown to mathematically account for the ionic contribution to conductivity; therefore, they are believed to be primarily responsible for the increase. However, the percentage of conductivity explained by the two ions was different over time. The percentage of conductivity attributable to NO3 increased in a pattern very similar to concentration. In contrast, the percentage of conductivity attributable to Ca2+ decreased slightly over time. The Ca2+ is believed to be pairing with the NO3 as the NO3 ions leach through the soil. While nitrification in mature stands can be strongly inhibited, limited nitrification , especially in forest gaps, and high anthropogenic inputs of NO3 probably were primary sources of the leached NO3. Preferential adsorption of SO 2-4, rather than NO3, on soil colloids is given as an explanation for the lack of retention of NO3 in the soil system and subsequent leaching to the stream.

    Publication Notes

    • Check the Northern Research Station web site to request a printed copy of this publication.
    • Our on-line publications are scanned and captured using Adobe Acrobat.
    • During the capture process some typographical errors may occur.
    • Please contact Sharon Hobrla, if you notice any errors which make this publication unusable.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Edwards, Pamela J.; Helvey, J. David. 1991. Long-term ionic increases from a central Appalachian forested watershed. Journal of Environmental Quality. 20(1): 250-255.

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page