Bog Plant Tissue Chemistry and N and S Accumulation in Peat are Influenced by Elevated N and S Deposition from Alberta Oil Sands Development
Abstract
Development of the oil sands resource in northern Alberta, Canada has led to elevated atmospheric N and S deposition, the N coming mainly from the exhaust of diesel fueled-trucks that haul the raw oil sands from the mine sites and the S coming mainly from refining. Against a background deposition of < 1 kg/ha/yr for both N and S, at sites within 15 km of the oil sands mining region we have measured current N and S deposition to be as high as 2 and 27 kg/ha/yr. With a goal of developing monitoring tools to assess the spatial extent of elevated N and S deposition in the region, we collected leaves, needles, or whole plants of 12 bog species (lichens: Cladina mitis and Evernia mesomorpha; Sphagnum mosses: S. capillifolium and S. fuscum; a tree: Picea mariana; ericaceous shrubs: Ledum groenlandicum, Oxycoccos microcarpus and Vaccinium vitis-idaea; deciduous forbs: Rubus chamaemorus and Smilacina trifolia) from 5 bogs ranging from 11 to over 250 km from the oil sands mining area. Samples were collected on 23 dates between May and October of 2009-2012 and were analyzed for C, N, and S concentrations. Six species (C. mitis, E. mesomorpha, S. fuscum, O. microcarpus, V. vitis-idaea, and R. chamaemorus) exhibited statistically significant increases in C:N ratio with increasing distance from the oil sands mining area. Five species (C. mitis, E. mesomorpha, S. fuscum, S. capillifolium, O. microcarpus) exhibited statistically significant increases in C:S ratio with increasing distance from the oil sands mining area. For three species (S. fuscum, E. mesomorpha, O. microcarpus), N concentrations gradually and significantly increased (C:N ratios decreased) over the four years of the study, with the rate of increase as high as 1 mg/g/yr at sites in close proximity to the oil sands mining area. In contrast, S concentrations in plant tissues generally did not increase over the four years, possibly because of increasing efforts to control S emissions from stacks. Using 210Pb-dated cores collected from 15 bogs ranging from ranging from 11 to over 250 km from the oil sands mining area, we demonstrated greater net N and S accumulation in peat over the most recent 25 years, as compared to the 25-50 time horizon. Moreover, net N and S accumulation decreased exponentially with distance from the oil sands mining region. These relationships indicate that higher N and S accumulation in peat is evident within a distance of about 20 km from the oil sands mining area. Our findings reveal that elevated N and S deposition from oil sands development affects plant tissue chemistry, with potential ramifications for both N and S cycling and potential vegetation change in bogs, and that atmospherically deposited N and S are retained in bog peat deposits.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.B43A0471W
- Keywords:
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- 0439 BIOGEOSCIENCES Ecosystems;
- structure and dynamics;
- 0414 BIOGEOSCIENCES Biogeochemical cycles;
- processes;
- and modeling;
- 0469 BIOGEOSCIENCES Nitrogen cycling;
- 0488 BIOGEOSCIENCES Sulfur cycling