Impact of Oils Sands Mining on Nitrogen-Limited Peatland Ecosystems in Alberta Canada
Abstract
Peatlands of boreal Canada represent large reservoirs of sequestered carbon (C) and nitrogen (N). Cycling of C and N in peatlands is intrinsically linked, especially in bogs - peatlands isolated from ground- and surface-water inputs, receiving nutrients exclusively from the atmosphere, which in the absence of N pollution, ensures an N-limited, nutrient-poor ecosystem. A growing concern associated with the development of Alberta’s Oil Sands Mining (OSM) is the potential for regionally elevated deposition of N-compounds (NOx). Prior to OSM, N inputs to bogs were limited exclusively to (1) biological N fixation, and (2) bulk atmospheric deposition. Currently, data examining the effect of purported increases in N and S deposition in this region are limited. Our goal was to determine patterns in atmospheric N deposition on N concentrations in bog porewaters at 5 sites spanning varying distances from the OSM region: Mildred, McKay, McMurray, Anzac and Utikuma bog (14, 24, 51, 71 and 300 km, respectively). Specifically, we wanted to test the hypothesis that OSM results in higher N deposition leading to elevated N in porewaters. Deposition of N was greatest at Mildred, followed by McKay, McMurray, and Anzac, and significantly lowest at Utikuma Bog (F4,49 = 5.9, p < 0.0006), supporting the first part of our hypothesis (Fig. 1). In contrast, dissolved inorganic N (TIN) concentrations in porewaters demonstrated significantly highest concentrations at Anzac, followed by significantly lower concentrations at McMurray, and least at McKay and Mildred (F3,147 = 25.9, p < 0.0001; Fig. 1), refuting the latter half of our hypothesis. Subsequent analyses reveal that site differences emerge with significantly elevated TIN in the 3 deepest depths (70-100 cm), with NH 4 + comprising the majority (~ 95 %) of TIN, suggesting the role of N deposition to bogs on in-situ N cycling processes be explored further. Figure 1. Atmospheric TIN (nitrate + ammonium) deposition (purple) and dissolved TIN concentrations (blue) in bog porewaters for each site. No porewater data are available for Utikuma. Bars with the same lower-case letter and same number are not significantly different. Atmospheric deposition was determined via ion-exchange resin samplers placed at each site (n=50 total; 10 per site) and porewaters were collected using a modified sipper design (n=15; 3 per site; 10-10cm depth intervals per sipper).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.B51H0449V
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0469 BIOGEOSCIENCES / Nitrogen cycling;
- 0470 BIOGEOSCIENCES / Nutrients and nutrient cycling