title: Spatio-temporal variation of erosion-type non-point source pollution in a small watershed of hilly and gully region, Chinese Loess Plateau.
abstract: Loss of nitrogen and phosphorus in the hilly and gully region of Chinese Loess Plateau not only decreases the utilization rate of fertilizer but also is a potential threat to aquatic environments. In order to explore the process of erosion-type non-point source (NPS) pollution in Majiagou watershed of Loess Plateau, a distributed, dynamic, and integrated NPS pollution model was established to investigate impacts of returning farmland on erosion-type NPS pollution load from 1995 to 2012. Results indicate that (1) the integrated model proposed in this study was verified to be reasonable; the general methodology is universal and can be applicable to the hilly and gully region, Loess Plateau; (2) the erosion-type NPS total nitrogen (TN) and total phosphorus (TP) load showed an overall decreasing trend; the average nitrogen and phosphorus load modulus in the last four years (2009-2012) were 1.23 and 1.63 t/km(2) · a, respectively, which were both decreased by about 35.4 % compared with the initial treatment period (1995-1998); and (3) The spatial variations of NPS pollution are closely related to spatial characteristics of rainfall, topography, and soil and land use types; the peak regions of TN and TP loss mainly occurred along the main river banks of the Yanhe River watershed from northeast to southeast, and gradually decreased with the increase of distance to the left and right river banks, respectively. Results may provide scientific basis for the watershed-scale NPS pollution control of the Loess Plateau.
authors.affiliation: College of Water Resources and Architectural Engineering, Northwest A&F University, No. 23 Weihui Street, Yangling District, Shaanxi, 712100, People's Republic of China. conquer2006@126.com.|State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China. conquer2006@126.com.|Key Laboratory of Agricultural Soil and Water Engineering in Arid Regions <Ministry of Education>, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China. conquer2006@126.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Wu
authors.affiliation: Construction Department, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Water Resources and Architectural Engineering, Northwest A&F University, No. 23 Weihui Street, Yangling District, Shaanxi, 712100, People's Republic of China.|Key Laboratory of Agricultural Soil and Water Engineering in Arid Regions <Ministry of Education>, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Ma
mesh_terms: D000383:Agriculture; D002681:China; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring / Q000379:methods; D004787:Environmental Pollution; D005308:Fertilizers; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers; D012987:Soil; D062211:Spatio-Temporal Analysis; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D005308:Fertilizers; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen
keywords: Chinese Loess Plateau; Dynamic model; Erosion-type nonpoint source pollution; Returning farmland; Spatio-temporal variation