Vol18 No.10: 2672-2687
【Title】Spatial and temporal variations in nitrogen retention effects in a subtropical mountainous basin in Southeast China
【Author】LIU Mei-bing1,2*; CHEN Xing-wei1,2; CHEN Ying1,2; GAO Lu2,3; DENG Hai-jun1,2
【Addresses】1 State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou 350007, China; 2 College of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China; 3 Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou 350007, China
【Corresponding author】LIU Mei-bing
【Citation】Liu MB, Chen XW, Chen Y(2021) Spatial and temporal variations in nitrogen retention effects in a subtropical mountainous basin in Southeast China. Journal of Mountain Science 18(10). https://doi.org/10.1007/s11629-020-6254-5
【Abstract】Nitrogen retention within a watershed reduces the amount of N exported to the ocean; however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool (SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.
【Keywords】Nitrogen retention; Riverine nitrogen output; Precipitation and runoff; Fertilization management; Subtropical mountainous basin