NO3 hotspots in pristine watershed of the Boreal Plain: interactions of local landforms and regional hydrogeology.
Abstract
Surface and ground water nitrate (NO3-N) concentrations of 3 mg/L, and often greater than 10 mg/L, are frequently observed in pristine watersheds of the Western Boreal Plain, Alberta, Canada. Such concentrations are greater then expected in non-disturbed locations, and in some cases are well above the WHO recommended levels. Nitrous oxide (N2O) fluxes from soil surfaces in these nitrate hot spots range from 10- 100, and on occasion greater then 500 ug/m2/h and may contribute significantly to global green house gas emissions. Nitrate hot spots are frequently observed in topographic low riparian areas with large water table fluctuations within humic organics sediments. However, their occurrence is not consistent in riparian zones across the landscape making it difficult to generalize N dynamics based solely on local influences of soil temperature, moisture and carbon dynamics. The Boreal Plain is characterized by sub-humid climate and deep heterogeneous glacial deposits resulting in complex surface - groundwater interactions with diverse geochemistry due to variable geologic strata that may also influence initial source and dynamics of N in individual riparian locations. We present representative distributions of surface and groundwater NO3-N concentration in the Boreal Plain, Alberta and put forward a series of hypothesis to assess the relative role and interaction of local soil and vegetation characteristics with hydrogeology on regional scale nutrient source, flow path and soil moisture regimes. Understanding the regional and local controls of nitrate hotspots in pristine boreal forest are essential to provide background references and allow for accurate assessment of the impacts of climate change and intensive land use currently affecting the Boreal Plain.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2009
- Bibcode:
- 2009AGUSM.H72B..01D
- Keywords:
-
- 0414 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0793;
- 1615;
- 4805;
- 4912);
- 0469 Nitrogen cycling;
- 1813 Eco-hydrology;
- 1871 Surface water quality;
- 1890 Wetlands (0497)