The Chemic Character Of Acid Precipitation In Liaozhong Area

Today,Acid rain is one of important environmental questions of the earth.Now,scientists calls acid rain is Azrael of air and killer of invisibility.Tt has brings huge wreck and effect to biogeoceno,enturonment and human produce and life.moreover it works imponderable economic losing。In the 70 age of 20th century,Chinese economy is developing with 8% rate,the fossil fuel is more and more used,a great deal of acid matters are letting,acid sections are formed in the south of the Changjiang River and the east of the SiChuan Basin. It is the third largested acid sections except the europeand the North America,include the U.K,France,Germany and U.S,Canada.moreover , it, , s rate and expanding area are egregious.Acid precipitation is more and more higher.It is few in the word,and stiring up our misgivings。Study of precipitation chemistry is always one of the highlight and hotspot of aomospheric wet deposition in China.Evaluating the level of precipitation pollution,studying translation and transportation of pollutants and analyzing harm to environment are based on chemical composition of precipitation.Liaozhong county is subjection to Shenyang,It is located in the southwest of Shenyang.TO understand the ionic composition characteristics of wet deposition and the source of pollutants at the Liaozhong.the results of precipitation chemistry measurements at the Liaozhong from February 2007 to January 2008 are reported.The eleven indexes for 30 collected samples weremeasured including pH value,electrical conductivity,the major water-soluble anion( K+,Na+,NH₄⁺,Ca²⁺,Mg2+,F-,Cl-,NO₃^-,SO₄^2-)。The relationship between the indexes and their sources were analyzed.The results showed that the wet deposition at the Liaozhong was acidic with the range and a volume-weighted average pH value of 3.40～7.34 and 4.76,respectively,and the frequency of acid wet deposition was 63.3%,strong acid precipitation(pH<4.5)account for 16.7 % , The range of sum ion concentration was 43.66～3924.72μeq/l with a volume-weighted average of 90 and the different of the maximum and the minimum concentration was approximate 606.41,SO₄^2-,NO₃^-,NH₄⁺ and Ca²⁺ were the most major ions of wet deposition in wet deposition with the volume-weighted average of 168.55,55.87,124.36 and 93.39,respectively. The range of concentration ratio of SO₄^2- and NO₃^- was 1.2～7.2 in the period of observation.The average value was 3.02 and less than the average level 6.4,This suggested that the contribution to acidification of atmosphere and wet deposition enhanced and the style of rain pollution was from the type of sulphur to the mixture type of vitriol and nitric acid.The range of [H+]/[( SO₄^2- + NO₃^-)] was 0.001～0.78, [H+]/[( SO₄^2- + NO₃^-)]with the average of 0.13,and showed SO₄^2-与NO₃^- existed in the form of neutralization in wet deposition.The major neutralization factors were NH4+å’ŒCa2+。There was a positive correlativity between pH valueand [(SO₄^2-+NO₃^-)]/[(NH4++Ca2+)],when [(SO₄^2-+NO₃^-)]/[(NH4++ Ca2+)] was equal to 1, pH value qualed to 5.3 closed to the critical value for acid rain,5.6,traditionally set,wet deposition was acidic.when [(SO₄^2-+NO₃^-)]/[(NH4++ Ca2+)]was higher than 1 and wet deposition was neutral or alkaline when it was less than 1.The statistical analysis indicated: Each kind of ions of wet deposition in Liaozhong may be divided in two kinds. K+, Na+, NH4+, Ca2+, Mg2+, F-, Cl-, NO₃^-, SO₄^2- were one kind, H+ were the second kind. The correlation coefficient between SO₄^2- and NO₃^-,the main factor leading to acid rain,was 0.897, showing that they have the same source.mostly came from the use of fuel and oil in industry and corporation, The relevance between SO₄^2-,NO₃^-and NH4+,Ca2+,K+ is remarekable, The correlation coefficient between SO₄^2-and NH4+,K+ is 0.925 and 0.777. The correlation coefficient between NO₃^- and NH4+,Ca2+,K+ is 0.825, 0.717 and 0.744。It indicatd that there were inverse correlation between SO2,, NOX,PM10 with pH value from the regression equation,As the precursor leading to acid rain, the quantity of SO2 and NOX increase will make the quantity of SO₄^2-å’ŒNO₃^- in the rain water increase. the precipitation pH value will reduce correspondingly; There were inverse correlation between PM10 and pH value.it showed that although the soil is alkalescence in Liaozhong, But the atmospheric suspended particle were acidic, It already lost it ,s ability to weaken the acid rain, As the source of NH4+,NH3 has played a role to weaken the acid rainThe result indicated that:wet deposition at the Liaozhong were seriously polluted by anthropogenic activities,acid precipitation occurred frequently,and sum ion concentration of wet deposition was very high and its range was wide.