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

Tao Bao,Dawei Ma,Wenjuan Ye,Hua Xu,Pei Wang,Renbin Zhu

doi:10.1038/s41598-018-21881-1

Tao Bao, Dawei Ma + Show 4 more

Open Access

https://doi.org/10.1038/s41598-018-21881-1

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Abstract

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 N2O and CH4 fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced N2O and CH4 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 N2O m−2 h−1 and 93 μg CH4 m−2 h−1, whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg N2O m−2 h−1 and 128 μg CH4 m−2 h−1. No statistically significant correlation (P > 0.05) was found between N2O and CH4 fluxes and soil temperature, soil moisture, total carbon, total nitrogen, NO3−-N and NH4+-N contents. Our results confirmed that UV radiation intensity is an important factor affecting tundra N2O and CH4 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.

Highlights

Enhanced N2O and CH4 emissions occurred at tundra sites under the simulated reduction of UV radiation
The use of filter membrane between experimental treatments significantly decreased (analysis of variance (ANOVA) and least significant difference (LSD) test, P < 0.05) the amount of UV radiation penetrating into the chamber (Table 1)
The highest mean UV-A and UV-B intensity occurred at the control site (14.4 ± 2.1 mW cm−2 and 4.7 ± 0.3 mW cm−2, respectively), followed by the site covered by 0.03 mm membrane (11.4 ± 1.6 mW cm−2 and 3.8 ± 0.3 mW cm−2, respectively) and the lowest at the site covered by 0.06 mm membrane (7.1 ± 1.0 mW cm−2 and 2.4 ± 0.2 mW cm−2, respectively)

Summary

Introduction

Enhanced N2O and CH4 emissions occurred at tundra sites under the simulated reduction of UV radiation. Our results confirmed that UV radiation intensity is an important factor affecting tundra N2O and CH4 fluxes in maritime Antarctica. Climate change might affect N2O and CH4 emissions from the tundra, because some soil parameters, e.g., soil moisture and temperature, are associated with microbial activity and the mineralization of organic carbon and nitrogen in soils[17,18,19]. Of vegetation litter in the Antarctic terrestrial ecosystem through the process of photodegradation[25,26,27] They have the potential to affect the structure and function of Antarctic mosses, Ceratodon purpureus and Bryum subrotundifolium[28] and to influence indirectly the soil microbial populations and activities[26]. It is important to investigate the effects of UV intensity on tundra N2O and CH4 fluxes and carbon and nitrogen cycles, in maritime Antarctica

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