Differences in N2O Spatio-temporal Distribution and Emission Reduction Potential in Three Gorges Reservoir Area
Nitrous oxide(N2O)is the world's third largest greenhouse gas after carbon dioxide(CO2)and methane(CH4)and is increasing year by year.The intensive development of agriculture and the advancement of urbanization in the Three Gorges reservoir area will also exacerbate N2O emissions.In order to understand the emission of N2O in the reservoir area and make suggestions for the low-carbon development.This study used the IPCC emission factor method and scenario analysis method to study the differences in N2O spatio-temporal distribution and to explore the emission reduction potential in the Three Gorges Reservoir Area.The results showed:(1)N2O emissions in the Three Gorges reservoir area remained at 14 700-16 200 t in 2006～2019.The overall emission trend was first higher and then decreased.The difference between 18 districts and counties in the reservoir area was significant(P＜0.01),and the spatial distribution was random(annual average Moran I ≈0 in the past 14 years).(2)Agricultural activities in the Three Gorges reservoir area were the main sources of N2O,while fertilizer application and fecal emissions contributed the most to N2O,accounting for 40.48％and 23.84％,respectively.By application of the STIRPAT model,it was found that among the driving factors of N2O emissions,the urbanization rate had constraining effects in the Three Gorges reservoir area,and the promotion factors from small to large were the grain output,the number of rural employees,the value-added of the primary industry and the per capita GDP.(3)The N2O emissions in the Three Gorges Reservoir Area in 2030 were predicted under three emission reduction scenarios.The forecast values were 15 500,13 400 and 12 100 t,respectively.In view of the N2O emissions and future predictions in the Three Gorges reservoir area,it was recommended that the amount of nitrogen fertilizer applied in farmland be controlled,and the management of livestock and poultry manure be strengthened,in the hinterland of the reservoir area.It was also suggested that a new agricultural mode be established.The circulation mechanism in the process of emission reduction should be further explored.Joint efforts should be considered in the future to control N2O emissions.
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