Posters

DISSOLVED ORGANIC CARBON AND NITROGEN DYNAMICS IN FOREST STREAMS, IN RELATION TO GEOSPATIAL AND HYDROTHERMAL CONTROLS
This poster shows how DOC and DON vary in stream and river water across watersheds in Atlantic Canada and the Turkey Lakes Watershed Study in Ontario near Sault St. Marie. The results show that DOC and DON increase but basin-exported nitrate-N decreases as the wet-area extent per basin increases.Presented at: International Society for Ecological Modelling (ISEM) Conference, Quebec City, Canada (October 6-9, 2009)
DISSOLVED ORGANIC CARBON CONCENTRATIONS AND FLUXES IN FOREST CATCHMENTS AND STREAMS: DOC-3 MODEL
There is considerable interest in knowing how much organic matter is transferred from uplands and wetlands into streams depending on general and specific basin characteristics. Some of the organic matter so transferred is solid, as in detritus, humified matter particles, of organically enriched sediments. Some of the organic matter is dissolved. Topography and vegetation distribution within the basin matter significantly in terms of type and amount of organic matter transferred. Typically, wetlands produce easily transferred dissolved organic matter (DOM). Upland soils do the same, but flowpaths are important: downward percolation tends to filter most of the dissolved organic matter that emerges from the organically enriched surface layers as part of the decompostion process. Surface run-off carries some of the dissolved materials into streams, but some of the surface water may flow into in pools, and remain there until the next flushing event. Meanwhile, exposure to sun, biological activity, and re-precipitation keep some of the DOM at bay. The presentation on the left presents the DOC-3 model by which upland/wetland DOC transfers into streams are quantified with the Forest Hydrology Model in terms of upland/wet-area distributions within and across basins, and by daily changes inflow rates and soil temperature and moisture, year-round. The DOC-3 model is then applied to determine DOC-related total Hg and total Hg – related MeHg concentrations and fluxes in stream water.Presented at: The 10th International Conference on Mercury as a Global Pollutant (ICMGP)
MODELLING DISSOLVED ORGANIC CARBON AND NITROGEN IN STREAMS AND RIVERS ACROSS ATLANTIC CANADA
Stream water sampling for 24 small to large watersheds across Atlantic Canada showed dissolved organic carbon (DOC) and nitrogen (DON) increased with increasing wet- area but decreased with increasing open-area percentages per basin. Highest DOC and DON concentrations were found for forested catchments with large wet-area and wetland proportions, and little to no open areas, specifically fields, barrens, or lakes. The day-to-day variations of these concentrations were highly synchronized according to local weather patterns, which allows for modelling based on local weather station records for precipitation and air temperature, while accounting for the upland-wetland transport of DOC and DON by way of surface water and groundwater flows. This presentation explores the implications of these patterns on upland-wetland-stream-lake DOC and DON transfer fluxes as affected by land-use and climate change, and discusses upland-wetland nitrate-N transfer and denitrification as well.Presented at: 65th Canadian Conference for Fisheries Research