Premium
Long‐Term Ionic Increases from a Central Appalachian Forested Watershed
Author(s) -
Edwards Pamela J.,
Helvey J. David
Publication year - 1991
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1991.00472425002000010040x
Subject(s) - watershed , nitrification , leaching (pedology) , conductivity , chemistry , streams , acid neutralizing capacity , environmental chemistry , soil water , environmental science , soil science , hydrology (agriculture) , nitrogen , geology , acid deposition , computer network , geotechnical engineering , organic chemistry , machine learning , computer science
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, NO − 3 and Ca 2+ 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 NO − 3 increased in a pattern very similar to concentration. In contrast, the percentage of conductivity attributable to Ca 2+ decreased slightly over time. The Ca 2+ is believed to be pairing with the NO − 3 as the NO − 3 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 NO − 3 probably were primary sources of the leached NO − 3 . Preferential adsorption of SO 2− 4 , rather than NO − 3 , on soil colloids is given as an explanation for the lack of retention of NO − 3 in the soil system and subsequent leaching to the stream.