Effects of canopy–deposition interaction on H⁺ supply to soils in Pinus banksiana and Populus tremuloides ecosystems in the Athabasca oil sands region in Alberta, Canada

Jung, Kangho; Chang, Scott X.; Arshad, M.A

Effects of canopy–deposition interaction on H⁺ supply to soils in Pinus banksiana and Populus tremuloides ecosystems in the Athabasca oil sands region in Alberta, Canada

2011

Jung, Kangho | Chang, Scott X. | Arshad, M.A (Charlie)

Soil acidification has been of concern in the oil sands region in Alberta due to increased acid deposition. Using the canopy budget model, and accounting for H⁺ canopy leaching by organic acids, we determined sources and sinks of H⁺ in throughfall in jack pine (Pinus banksiana) and trembling aspen (Populus tremuloides) stands in two watersheds from 2006 to 2009. In pine stands, H⁺ deposition was greater in throughfall than in bulk precipitation while the opposite was true in aspen stands. The annual H⁺ interception deposition was 148.8–193.8 and 49.7–70.0molcha⁻¹ in pine and aspen stands, respectively; while the annual H⁺ canopy leaching was 127.1–128.7 and 0.0–6.0molcha⁻¹, respectively. The greater H⁺ supply in pine stands was caused by greater interception deposition of SO₄ ²⁻ and organic acids released from the pine canopy. Such findings have significant implications for establishing critical loads for various ecosystems in the oil sands region.

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