Investigation About Acid Rain Pollution And Mitigation Countermeasures In Zhenhai District

Acid rain as a global environmental problems, receives increasingly attention in China. Zhenhai District of Ningbo City, as a major port and heavy chemical industry base,possesses petrochemical industry, energy and other industries. There are 32 state,province or city-owned large enterprises locatated in this region. Six of these enterprises are the main sources of sulfur dioxide emissions. Acid rain pollution increases year by year.The changes of acid rain monitoring and atmospheric pollution data are analyzed during the period of 2003 to 2008. Survey results showed that:Beginning in 2004,the annual average value of pH declines and the frequency of acid rain rises. PH of acid rain is a significant change in the year. A performance of monthly average PH is lower PH in winter and spring,higher PH in summer and autumn from 2003 to 2008. PH of autumn is the highest in the year. This variation relates with atmospheric pollution and meteorological factors. In winter and spring,concentrations of sulfur dioxide and nitrogen dioxide of atmospherie are higher than in summer and autumn. The greatest impact anion on the acidity of precipitation is SO₄^2-, followed by NO₃^-, and NH₄⁺ and Ca²⁺ is mainly impact anion. The acidic ion of precipitation is accounts for a dominant position,and concentration of acidic ion shows an increasing trend, neutralization effect is existed, alkaline substances and acid rain but the effect is little. The ratio of SO₄^2-/ Na⁺ and ratio of Ca²⁺ / Na⁺ in precipitation is far greater than in seawater, that shows SO₄^2- and Ca²⁺ in precipitation are mainly from industrial pollution and dust.The impact of sea salt is little. The type of acid rain in Zhenhai is coal-burning pollution and automobile exhaust pollution plays a subsidiarity.But,automobile exhaust pollution is increasing year by year.Comparing monthly average pH of precipitation and results simulated by the Acid Rain Model shows that five months’ model simulation results is less than the measured pH, the rest of the months of simulation results were greater than the measured value. According to the wind direction of acid rain measuring point, long-range transportation of atmospheric pollutants coming from the outside of Zhenhai is existed in Zhenhai,that makes the local concentration of atmospheric pollutants increasing, acidification of precipitation being serious. Another reason that the calculated value is greater than the measured value is not considered to simulate motor vehicle exhaust emissions.According to the state acid rain and sulfur dioxide pollution control measures, combining with Zhenhai’s situation, it proposes the measures to decrease sulfur dioxide emission of coal-fired power plants and to control acid rain pollutants.