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为了探究西安市畜禽粪便污染现状,对各区县的农田耕地和水质进行环境质量评价。在确定畜禽粪便年排放量的估算方法和畜禽粪便排泄系数的基础上,估算了2012年西安市畜禽粪便年产生量和主要污染物产生量。在了解各农业非点源污染成因的基础上,针对不同的污染源,提出了一些初步的控制对策和措施。结果表明,2012年西安市畜禽粪便总排放量约为498.41万t,其中牛和猪的排放量较高,分别占总量的46%和37%。畜禽粪便污染物COD、TP和TN产生量分别为12.52万t、8950 t和2.8万t。西安市部分区县的农田耕地负荷警报值分别达到Ⅱ级和Ⅳ级,已不同程度的超过了当地农田耕地的消纳能力,对环境构成污染威胁。畜禽粪便污染物入河情况十分严重,各污染源中,牛尿的污染率指数高达33.5%;各污染物中总氮和总磷的污染率指数分别为52%和41.5%。部分地区的畜禽养殖已经对西安市环境构成污染。
In order to explore the status quo of livestock and poultry manure pollution in Xi’an, the environmental quality of farmland and water quality in each county was evaluated. Based on the estimation of the annual discharge of livestock manure and the excretion coefficient of livestock excrement, the yearly output of livestock excrement and the generation of major pollutants in Xi’an in 2012 were estimated. On the basis of understanding the causes of agricultural non-point source pollution, some preliminary control measures and measures are put forward for different sources of pollution. The results showed that in the year of 2012, the total manure discharge in Xi’an was about 4,984,100 tons, of which the emissions of cattle and pigs were higher, accounting for 46% and 37% of the total respectively. The COD, TP and TN production of livestock excrement pollutants were 125,200 t, 8950 t and 28,000 t, respectively. In some districts and counties of Xi’an, the farmland arable land load warning value reached Grade II and Grade IV, respectively, which exceeded the digestion capacity of farmland in local areas to varying degrees and posed a pollution threat to the environment. The situation of livestock and poultry excrement entering the river is very serious. The pollution index of cow urine is as high as 33.5%. The pollution index of total nitrogen and total phosphorus in each pollutant is 52% and 41.5% respectively. Livestock and poultry farming in some areas has polluted the environment in Xi’an.