Abstract: Global warming in the polar regions strongly influences the processes and rates of material cycling in the polar region ecosystems. In this study, the effects of global warming on the key process of nitrogen cycle processes in Antarctic lake sediments are reported. During the 29th Chinese National Antarctic Research Expedition, five lakes located near the Zhongshan Station were selected, one with sediments containing penguin manure (Mochou Lake) and four with natural lake sediments (Tuanjie Lake, Daming Lake, Mier Lake and Yuzhen Lake). The “sample-bottle mud constant-temperature mud culture method” was used to simulate temperature increases. Culture experiments were set at low temperature (1℃), medium temperature (5℃) and high temperature (11℃).  Results showed that the denitrification rate and denitrification potential of Mochou Lake sediments at low temperature were significantly higher (277.37 times and 246.73 times, respectively) than those of natural lake sediments. Limitted warming enhanced the sediment denitrification rate and potential, but excessive temperature increase inhibited the denitrification in some samples. At high temperature, the average denitrification rate of natural lake sediments under high temperature was 1.57 times and 3.56 times higher than at medium and low temperature, respectively, while the denitrification potential represented 1.91 times and 6.31 times the medium and low-temperature rates, respectively. For Mochou Lake sediments at high temperature, the denitrification rate was 1.78 and 2.07 time higher, and the denitrification potential was 0.72 and 1.01 times higher, respectively, than at medium and low temperature. Although the warming-induced relative increase in denitrification rate and denitrification potential was higher for natural lake sediments than for the Mochou Lake sediments, the absolute increase was higher at Mochou Lake. Higher contents of nitrate, ammonium salt, phosphate and organic carbon in penguin manure explain this high denitrification rate. Under global warming conditions, exogenous nitrogen input from penguins accelerates the nitrogen cycle in Antarctic lake sediments.

Key words: warming, Antarctic, lake sediment, denitrification