Date of Award

Spring 2010

Project Type

Thesis

Program or Major

Natural Resources: Water Resources

Degree Name

Master of Science

First Advisor

William H McDowell

Abstract

Nitrate (NO3-) uptake and denitrification in small headwater streams can have significant implications for downstream water quality. I measured seasonal NO3- uptake and longitudinal patterns in potential sediment denitrification in a New Hampshire agriculturally influenced stream during 2009. NO3- uptake was measured through short-term NO3- enrichments and potential denitrification was measured using the Chloramphenicol-amended acetylene-inhibition method. NO3 - was taken up in autumn but not in spring or summer. In autumn, on average 87% of the daily NO3- load was taken up and a maximum of 4% was removed via denitrification. Results suggest that, in this stream, carbon availability from leaf fall drives NO3 - uptake primarily via heterotrophic assimilation. This study helps to better characterize controls on NO3- uptake and denitrification in New England, where few such studies have been conducted on agricultural streams, and where seasons are pronounced.

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