EFFECT OF CLIMATE WARMING AND EUTROPHICATION ON N2O FLUX AT WATER-AIR INTERFACE OF SHALLOW LAKES
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Abstract
Our study built the shallow-lake mesocosm to simulate the N2O exchange process at the water-air interface throughout the whole experimental periods under climate change and eutrophication. (1) Results of the mesocosm experiment demonstrated that constant and fluctuate warming significantly promoted N2O emissions and annual accumulating emissions due to changes in metabolic processes and biotic interactions. Phosphorus addition affected the efficiency of denitrification metabolism in water to weaken the N2O emission at the water-air interface and annual cumulative emission; (2) In the experimental periods, the dominant primary producer in the mesocosm changed from aquatic plant to phytoplankton, and the organic matter content in the water body accumulated continuously. Our study showed that the above two factors have a significant effect on the increase of N2O emission from the water-air interface, and that the fluxes of N2O from shallow lakes under climate change and eutrophication trends were mainly affected by changes in the ratios of N and P in water bodies and primary producers in the accumulation of organic matter. We concluded that constant and fluctuating climate warming can tilt the N2O balance to higher emission, and the combination of warming and nutrients can cause complex interactions in the N2O exchange in the water-air interface.
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