Date of Award
2008
Degree Type
Thesis
Degree Name
Master of Science
Program
Biology
Supervisor
Dr. Irena Creed
Abstract
This study sought to explain differences in dissolved nitrogen (N) export between catchments in the Turkey Lakes Watershed. Neighbouring catchments c35 and c38 have similar N inputs, but a discrepancy in dissolved N export. It was hypothesized that gaseous N export from wet soils accounted for this discrepancy as c35 contains few isolated wet soils, whereas c38 contains many connected wet soils. To test this hypothesis, N2O efflux from soils was measured during the growing season in 2006 and 2007. Minimal N2O efflux (< 1 g N ha1 day1) was observed on days without rain. However, on days with rain, N2O efflux was observed, with a linear increase in the rate of N2O efflux from wet soils of 0.016 g N ha1 day1 (r2=0.60, p<0.001) per millimetre of rain. Intensive monitoring of the wetland soil profile suggested that rain delivers water to the surface layers of the wetland creating an oxygen poor environment where accumulated NO3 is transformed to N2O then N2. The discrepancy in dissolved N export between c35 and c38 was explained when N2O and associated N2 efflux (based on a ratio of 10N2:1N20) from the wet soils in c38 were considered. This study suggests that rain can produce substantial bursts of N2O and N2 from forest soils and that failure to account for gaseous N export may lead to an underestimation of N export from forested catchments.
Recommended Citation
Casson, Nora J., "Rain induced bursts of denitrification activity account for differences in dissolved nitrogen export from forested catchments" (2008). Digitized Theses. 4751.
https://ir.lib.uwo.ca/digitizedtheses/4751