title: Evaluating anthropogenic N inputs to diverse lake basins: A case study of three Chinese lakes.
abstract: The environmental degradation of lakes in China has become increasingly serious over the last 30 years and eutrophication resulting from enhanced nutrient inputs is considered a top threat. In this study, a quasi-mass balance method, net anthropogenic N inputs (NANI), was introduced to assess the human influence on N input into three typical Chinese lake basins. The resultant NANI exceeded 10,000 kg N km(-2) year(-1) for all three basins, and mineral fertilizers were generally the largest sources. However, rapid urbanization and shrinking agricultural production capability may significantly increase N inputs from food and feed imports. Higher percentages of NANI were observed to be exported at urban river outlets, suggesting the acceleration of NANI transfer to rivers by urbanization. Over the last decade, the N inputs have declined in the basins dominated by the fertilizer use but have increased in the basins dominated by the food and feed import. In the foreseeable future, urban areas may arise as new hotspots for nitrogen in China while fertilizer use may decline in importance in areas of high population density.
authors.affiliation: College of Environmental Sciences and Engineering, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing, 100871, China. jacob@pku.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14850, USA. dps1@cornell.edu.
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Swaney
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14850, USA. bh43@cornell.edu.
authors.forename: Bongghi
authors.initials: B
authors.lastname: Hong
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14850, USA. howarth@cornell.edu.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Howarth
authors.affiliation: College of Environmental Sciences and Engineering, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing, 100871, China. yongliu@pku.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Environmental Sciences and Engineering, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing, 100871, China. guohc@pku.edu.cn.
authors.forename: Huaicheng
authors.initials: H
authors.lastname: Guo
mesh_terms: D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D058735:Environmental Policy / Q000331:legislation & jurisprudence; D060106:Lakes / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D014874:Water Pollutants, Chemical; D009584:Nitrogen
keywords: Eutrophication; Lake; Net anthropogenic N inputs (NANI); Nitrogen; Nonpoint source