Date of Award

Winter 2012

Project Type


Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

William H McDowell


Degradation of dissolved organic carbon by microbial and photolytic processes was examined along the main stem of the Lamprey River Watershed located in southeastern New Hampshire. Eight sites were chosen and sampled biweekly throughout the seasonal hydrograph. Lab incubations were employed to assess microbial degradation of dissolved organic carbon (DOC) where one set of samples was exposed to natural sunlight for a day to assess photolytic degradation. Mean biodegradable dissolved organic carbon (BDOC) throughout the study period was 5.8% with no significant variation observed between sites. Temporal variation was found to be a much stronger driver of DOC composition with summer showing the highest degradation of 8.6% and winter the lowest. Initial DOC concentration was found to be the only significant positive predictor of BDOC on both an annual and seasonal scale. Photolysis had no significant effect on DOC degradation or availability of DOC to the microbial pool. Findings suggest that temporal variation is a significant driver of DOC composition via DOC sources that change throughout the season.