PARENT SESSION
Poster Session 32: Biogeochemistry
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

The Rates of Methane Oxidation in a Temperate Forest Soil in Korea.

Jang, Inyoung^*,1, Kang, Hojeong¹, ¹ Ewha Womans University, Seoul, Repubilc of Korea

ABSTRACT- Methane, the main carbohydrate in the atmosphere, contributes ca. 20% of global warming effects. Forest soils are known to oxidize methane by the action of methanotrophic bacteria, which plays a key role in methane cycle. We measured methane oxidation rates on a monthly basis from May 2004 to April 2005 in a temperate forest in Korea. The measurements were made in two ways. Firstly, we used a static chamber method by which in situ rates of methane oxidation (natural rates) were determined. In addition, oxidation potential was determined by injecting high concentrate methane (150 ppmv) and following the changes in the concentration in a closed bottle filled with soil samples. Natural rates varied from 0.55 to 8.67 mg CH₄ m^-2 day^-1 while potential rates ranged between 0.021 and 0.085mg CH₄ g^-1 soil day^-1. The natural rates measured in situ exhibited a significant positive correlations with pH and DOC. In contrast, the potential rates were positively correlated with water content (p < 0.01). Methane oxidation in winter was higher than that in summer. As methanotrophic bacteria can consume the NH₄⁺, existence of NH₄⁺ is believed to inhibit methane oxidation. Yet our experiment showed no significant correlation between ammonium and methane consumption in forest floor. To understand these results, we conducted laboratory-based manipulation experiments. We added NaNO₃, NH₄NO₃, (NH₄)₂SO₄, NH₄NO₃ or distilled water to soil to elucidate effects of ions on methane oxidation rates. The results showed that addition of NH₄⁺ did not affect methane oxidation while Na+ or NO₃^- addition inhibit oxidation rates significantly. In conclusion, the rates of methane oxidation of temperate forest in Korea are comparable to previous reports in other countries, and NO₃^- may inhibit oxidation while no such effect was found by NH₄⁺. This study was supported by Korea Nation′s Baseline Ecological Research (KNBER) and Advanced Environmental Biotechnology Research Center (AEBRC).

Key words: Methane oxidation, Forest soil, N deposition, Envrionmental factors