Groundwater Pollution And Its Prevention And Measures In Xi'an Urban Area

This paper selects groundwater in Xi'an city as research object, based on present datas, combined hydrogeology with environmental science, according as theory and methods of hydrochemisty, environmental geochemistry, environmetal quality assessment and pollution assessment and so on, analyses characteristics of groundwater pollution and main pollution sources in Xi'an; evaluates groundwater environmetal quality and analyses pollution trend, then puts forward measures for pollution, providing references to protection of groundwater resources and improvement of pollution in Xi'an city.1. By contrasting groundwater chemical constituents in 2005 to 2004, results indicate: overproof sites of fluorid and iron in groundwater decreased, however overproof sites of total solid, total hardness, chlorid and chrome increased a little; in confined water, overproof sites of total solid, nitrite, manganese and iron in 2005 are respectively one, two, one and one less than that in last year, and there is one more overproof site of total hardness than last year.2.The main groundwater pollution sources are industrial sewage, industrial waste gas, surface water, sewage irrigation and pesticide and chemical fertilizer using, urban sanitary waste. And industrial sewage pollution of paper making and paper products industries are most serious; chief pollutional industries of industrial waste gas are electric power and heating power production supply industries.3.According to groundwater quality monitoring datas from 2001 to 2005, taking use of comprehensive index assessment method to evaluate groundwater environmental quality in Xi'an city, result is that best area, good-better area, worse area and worst area takes 48.9%,15.7%,34.75% and 0.65% of assessment area respectively.4.Taking use of Daniel trend examining test to inspect the trend of groundwater pollutants from 2001 to 2005, results are as follows: in recent five years, all of the trends of total solid, total hardness, chloride, chrome and fluoride pollution are decreasing; there was no obvious change for nitrate radical; arsenic and hydroxybenzene were not measured out for many years, so its amount didn't change basicly.5.Based on datas of groundwater quality from 2001 to 2005, analysed trend of five kinds of main pollutants' overproof area, results show that overproof area of total hardness is reducing most evidently, average reducing rate is 11.50km~2 /a; rate of nitrate and total solid is 7.2km~2 /a and 6.9km~2 /a; trend of fluorid overproof area is decreasing as a whole, average rate is 5.56km~2 /a; trend of chrome overproof area is decreasing too.At last, according to the results of analysing groundwater pollution status and trend, bring forward groundwater pollution countermeasures in Xi'an city from technology and administer aspects to improve groundwater environmental status and coordinate social economy and evironment of Xi'an.