Analysis Of Characteristics Of Atmospheric Precipitation In Beijing Urban Area

Precipitation is the most efficient and effective way to remove atmosphericpollutants.Geographical conditions, seasonal change, amount of precipitation, pr ecipitation acidity, the types of weather, and many other factorswill lead precipi tation chemistry different, even in the same place and the same precipitation,th e different times of the chemical composition and the characteristics have signi ficant differences. In order to researchthe characteristics of chemical compositio n of precipitation and its influencing factors, precipitation wasmonitoredthrough out the year in 2015 in the Beijing urban area. It analyzed the p H value, condu ctivity, 10 kinds of water-soluble inorganic ions and 25 kinds of water-soluble metal element concentration changing with the rainfall time, concentration of w ater soluble inorganic ions and water-soluble metal elements of influencingfacto rs, conclusions are summarized as follows:1.At the beginning of the precipitation, the values ofp H, EC, water soluble inorganic ion concentration and water-soluble metal element concentration are high, middle and later periods of the precipitation concentration change is slow, and gradually stabilized. The value of p H showed a positive correlation with precipitation, the value of EC showed a negative correlationwith precipitation.2.Beijing precipitation of 10 kinds of water-soluble inorganic ions Na⁺,NH 4+,K⁺,Mg²⁺,Ca²⁺,F^-,Cl^-,NO 2-,NO₃^-,SO₄^2-weighted average concentrationwere 0.96, 2.69, 0.83, 0.24, 1.46, 0.09, 1.48, 0.07, 3.90, 4.79 mg/l, the concentration oforde r:SO₄^2-?29?NO₃^-?29?NH₄⁺?29?Cl^-?29?Ca²⁺?29?Na⁺?29?K⁺?29?Mg²⁺?29?F^-?29?NO₂^-.Throughout the 2015 yearp recipitation processin Beijing,cation ion of NH₄⁺and anionion of SO₄^2- are domin ant.3.Beijing precipitation 25 kinds of water-soluble metal elements content int he order:K>Ca>Na>Mg>Fe>Zn>Al>Mn>Ba>Sb>Pb>Cu>Ni>Cr>As>Se>Ag>V>Cd>Co>Mo>Tl>Be>U>Th.Water-soluble metal element EF size order: Sb>Se>Ag>C d>Zn>As>Pb>K>Tl>Mo>Cu>Ni>Na>Cr>Ca>Ba>Be>Mn>Mg>Co>U>V>Th>Fe>A l.In addition to the elements such as Al,Fe,Th,V, most elementsenrichment.4.The spring precipitation mainly comes from north air, the summer precip itation mainly comes from south air, the autumn and winter precipitation are m ainly come from the northwest air. The average concentration of SO₄^2-, NO₃^-,NH₄⁺ in south air are about 2³times bigger than in northern air,and the average concentration of Na⁺,K⁺,Cl^-ion are lower than the northwest air. The average c oncentration of water-soluble metal elementsin south air is higher than in north ern air.Most of the ions in the same precipitation havehomology.5.Water-soluble metal elements Ag, K,Na,Th,Pb,Mn, Be, Ca, Se, Cu, Zn, Cr and Co appear certain positive correlation with precipitation, and Ag, Kand N a elements appear significant correlation with precipitation?P<0.05?;Water-soluble metal elements Na, Th, Mn, Tl, Ca, Pb, Cd, Ag, K, U, Al, As, Mg, V, Zn, S b, Ni, Cuappear certain positive correlation with p H value,and Na, Th, Mn, Tl,Ca, Pb, Cd,Ag, K, U elements appear significant correlation withp H value?P<0.05?.