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Nitrate Depletion in a Second‐Order Mountain Stream
Author(s) -
Swank Wayne T.,
Caskey William H.
Publication year - 1982
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/jeq1982.00472425001100040006x
Subject(s) - watershed , hydrology (agriculture) , environmental science , streams , sediment , denitrifying bacteria , nitrate , denitrification , stream flow , discharge , nitrogen , chemistry , ecology , geology , drainage basin , geography , biology , geomorphology , computer network , geotechnical engineering , cartography , organic chemistry , machine learning , computer science
The amount of NO 3 ‐N exported in a second‐order mountain stream draining a clearcut and logged mixed hardwood forest was studied over a 4‐year period. Calculations based on measurements of stream chemistry and discharge rates indicated a within‐stream depletion of NO 3 from the upper reaches of the stream to the watershed outlet. Within‐stream depletion the first year of treatment was 127% of total NO 3 ‐N discharged from the watershed outlet and declined in succeeding years after treatment to 99, 42, and 5%. Assays of the quantities of denitrifying enzymes in stream sediment samples suggested 1.7 kg N year −1 were lost via this pathway, compared with 3.9 kg N year −1 calculated from within‐stream depletion for the same time period. This study suggests sediment denitrification is a major pathway by which NO 3 ‐N is lost. Within‐stream gaseous transformations are important when accounting for changes in N dynamics associated with forest management practices, and the measurement of only hydrologic discharge of NO 3 could result in underestimation of N losses.