河套灌区总排干沟氮污染负荷分割与估算

DIVISION AND ESTIMATION OF NITROGEN POLLUTION LOAD IN THE GENERAL MAIN DRAIN OF HETAO IRRIGATION AREA

针对日益突出的农业非点源污染问题,区分河套灌区的点源污染与农业非点源污染显得十分必要。考虑灌区点源和农业非点源污染的形成和运移规律,依据总排干沟红圪卜断面2009-2017年水文水质同步观测资料,采用水文分割法研究总氮(TN)污染负荷。结果表明:总排干沟属于典型的点面污染混合沟;TN污染总负荷除2012年由农田排水量过大导致升高外总体在下降,降幅39.1%;点源TN污染负荷呈下降趋势,点源TN污染负荷平均为3 076.20 t,2017年较2009年削减了50.6%,点源污染得到有效控制;2012年以来非点源TN污染加剧,非点源TN污染负荷平均为1 793.09 t,占年平均总负荷量的36.82%。总排干沟氮污染以点源为主,2012年以来,氮污染得到了一定的控制。针对点源污染要以控制点源污染物浓度为重点,对于非点源污染要以减少农田排水量为重点。

Aiming at the increasingly prominent problem of agricultural non - point source pollution, it is necessary to distinguish between point source pollution and agricultural non 一 point source pollution in Hetao irrigation area. Total nitrogen pollution load was studied on the basis of hydrology division method, the formation and transport mechanism of the point source and the agricultural nonpoint source pollution and synchronous monitoring data of hydrology and water quality on Honggebu section of the general main drain from 2009 to 2017. The results showed that the general main drain was a typical mixed drain composed of point source and non-point source pollution. The total pollution load of total nitrogen was decreasing by 39. 1%,in addition to the increase by excessive drainage of farmland in 2012. The point source pollution load of total nitrogen whice decreased by 50. 6% in 2017 compared with 2009 was effectively controlled, and the average point source pollution load of total nitrogen was 3 076. 20 t in 2009-2017. The average non - point source pollution load of total nitrogen was 1 793.09 t in 2009-2017,which accounted for 36. 82% of the annual total load,however the non - point source pollution has intensified since 2012. Nitrogen pollution of the general main drain was mainly based on point source. Since 2012, nitrogen pollution has been controlled. The point source pollution should be focused on controlling point source pollution concentration and the non 一 point source pollution should be focused on reducing farmland drainage.