Landscape Influences on Dissolved Organic Carbon, pH, Fe, and Ca in 37 Lakes in the Forest-Tundra of Northern Manitoba, Canada
Abstract
DOC, pH, Fe, and Ca are major influences on lake ecosystems, and all three may be impacted by the surrounding catchment, especially the presence of wetlands and coniferous forest. To better understand past and future lake responses to climate change in the sub-arctic forest-tundra of northern Manitoba, we measured DOC, SUVA, pH, Ca, and Fe in 37 lakes in 2008 and 2009, we mapped wetlands, forest, and other cover types based on a supervised classification of Landsat 7 imagery using 100 and 200 m buffers, and we delineated catchment boundaries based on a 50K DEM or the recently released ASTER global DEM. DOC (2.51 - 9.93 mg l-1), SUVA (2.08 - 11.19 L mg-C-1 m-1), and Fe (0.004 - 11.16 mg l-1) and Ca (0.32 - 8.12 mg l-1) showed considerable among-lake variation, and lakes were generally acidic (average pH 4.86, range 3.74 - 7.64). As observed in previous studies, DOC and Fe were strongly positively correlated (r =0.74), but DOC, SUVA, pH, and Fe were only weakly to moderately correlated with each other (r < 0.40). Percent area of both wetlands and coniferous wetlands within the 100 or 200 m buffers was strongly positively correlated with Fe (r = 0.55) and DOC (r = 0.68) but not with pH (r=0.25). pH and Ca were positively correlated (r=0.64), and lakes with relatively more lowland coniferous forests within 100-200 m of the lake edge had higher Ca (r = 0.36). In general cover type percentages within the delineated catchments were only weakly correlated measured lake water chemistry which may indicate problems with the DEMs and consequent catchment delineation in such a flat landscape, or it may suggest more limited movement of water within this landscape.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.B43A0345U
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0458 BIOGEOSCIENCES / Limnology;
- 0475 BIOGEOSCIENCES / Permafrost;
- cryosphere;
- and high-latitude processes;
- 0480 BIOGEOSCIENCES / Remote sensing