Effects of sunlight on tundra nitrous oxide and methane fluxes in maritime Antarctica

The relationships of nitrous oxide (N2O) and methane (CH4) emissions to other environmental parameters have been studied extensively in Antarctic terrestrial ecosystems. However, the effects of sunlight on soil N2O and CH4 fluxes are neglected across the Antarctic tundra. Here, fluxes of N2O and CH4 from maritime Antarctic tundra soils were measured in the absence and presence of sunlight during three summers. The N2O fluxes averaged ?4.6±1.2 μg·m?2·h?1 in the absence of sunlight and 5.7±1.5 μg·m?2·h?1 in its presence; CH4 fluxes averaged 119.8±24.5 μg·m?2·h?1 (absence) and ?40.5±28.3 μg·m?2·h?1 (presence). The correlations between N2O and CH4 fluxes and other environmental variables (e.g., soil moisture, temperature, organic and inorganic material) were not statistically significant (P>0.05) at all sites. On average, sunlight significantly increased N2O emissions and CH4 uptake by 10.3 μg·m?2·h?1 and 160.3 μg·m?2·h?1, respectively. This study indicates that sunlight is critical for accurately estimating N2O and CH4 budgets from maritime Antarctica and necessary for constraining the role of their emissions from tundra soil.