汉中市农村面源污染时空变化研究

Study on temporal and spatial variation of non-point source pollution in rural areas of Hanzhong city

采用源强法估算2009—2017年汉中市农村面源污染,基于ArcGIS软件分析其时空格局。研究表明:(1)农村生活污水TN、TP、COD排放量年平均分别减少了35.41、10.12、378.72 t,固体污染物TN、TP、COD排放量年平均分别减少了233.08、16.85、1 407.71 t,农业化肥污染物TN、TP、COD排放量年平均分别增加了93.37、80.52、135.32 t,农用塑料薄膜使用量年平均增长了74.75 t;(2)空间上,洋县、略阳县、宁强县属于持续高污染型,佛坪县、镇巴县属于持续低污染型,南郑区、汉台区属于污染减轻型,西乡县、勉县、留坝县、城固县属于污染增加型;(3)人口转型、耕地减少、技术变化、环保政策等综合决定面源污染的变化,地形、产业结构在污染时空变化中起到重要影响。

The source strength method was used to estimate the rural non-point source pollution in Hanzhong city from 2009 to 2017.The temporal and spatial pattern was analyzed based on ArcGIS 8.3.The results showed that:(1)The annual average TN,TP and COD emissions of rural domestic sewage decreased by 35.41,10.12 and 378.72 t respectively.The annual average TN,TP and COD emissions of solid pollutants decreased by 233.08,16.85 and 1407.71 t respectively.The annual average TN,TP and COD emissions of agricultural chemical fertilizer pollutants increased by 93.37,80.52 and 135.32 t respectively.The amount of plastic film increased by 74.75 t per year on average.(2)Yang county,Luyang county and Ningqiang county belong to the category of continuous high pollution;Foping county and Zhenba county belong to the category of continuous low pollution;Nanzheng district and Hantai district belong to the category of pollution mitigation.Xixiang county,Mian county,Liuba county and Chenggu county belong to the category of pollution increase.(3)The change of non-point source pollution is determined by population transition,decrease of cultivated land,technology change and environmental protection policy.Topography and industrial structure play an important role in the temporal and spatial variation of pollution.