Potential effects of ultraviolet radiation reduction on tundra nitrous oxide and methane fluxes in maritime Antarctica.

Stratospheric ozone has begun to recover in Antarctica since the implementation of the Montreal Protocol. However, the effects of ultraviolet (UV) radiation on tundra greenhouse gas fluxes are rarely reported for Polar Regions. In the present study, tundra NO and CH fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced NO and CH emissions occurred at tundra sites under the simulated reduction of UV radiation. Compared with the ambient normal UV level, a 20% reduction in UV radiation increased tundra emissions by an average of 8 μg NO m h and 93 μg CH m h, whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg NO m h and 128 μg CH m h. No statistically significant correlation (P > 0.05) was found between NO and CH fluxes and soil temperature, soil moisture, total carbon, total nitrogen, NO-N and NH-N contents. Our results confirmed that UV radiation intensity is an important factor affecting tundra NO and CH fluxes in maritime Antarctica. Exclusion of the effects of reduced UV radiation might underestimate their budgets in Polar Regions with the recovery of stratospheric ozone.