The Study On Atmospheric Wet Deposition In Qingdao

Totally, 61 rainwater samples were collected at Qingdao from March 2002 to December 2003 . Major anions and cations and some inorganic nutrients were analyzed . The anions (F^-, Cl^-, SO₄^2-) were analyzed by IC (Ion chromatography) and cations (K⁺,Na⁺, Ca²⁺ ,Mg²⁺) by FAAS (Flame Atomic Absorption Spectrometry) and nutrients (NH₄⁺,NO₃^-,NO₂^-,PO₄^3-,SiO₃^2-) by autoanalyser. The quality control was under taken for all the ions studied .The results showed that the ion concentration of rainfall changes with a wide range and had great dispersion which indicated that the chemical constituents varied much in the different precipitation events .Good correlation existed between the total anions and cations .95.1 percent of the samples were in ion balance . The rainfall ion compositions of Qingdao area were influenced both by ocean and terrene , ion compositions were similar across the study period , so the terrestrial influence must be mainly controlled by local pollution source . Ion concentration was inverse related to the rainfall . The relationship between rainfall and H⁺ was more complex than other species and regular changing characteristics could be observed . Monthly average concentrations changed widely that the high values always occur in winter or spring but low values in summer.pH<5.0 was the criterion for acid rain . 35.3% of the precipitations in 2003 , 55.6% in 2002 and 64.9% in 1998 were acid rains .Analyzing the relationship of the pH and the main/base ions indicated that SO₄^2- was the main contributor , and a good linear relationship was found between the pH and the ratio of (NO₃^- + 2SO₄^2-)/(2Ca²⁺ +NH₄⁺) . Instead of the concentration of acid ions decreased as the reason of the frequency of acid rain decreased year by year , we observed the base ions increased .The monthly atmospheric wet depositions flux of nutrient elements were not only related with the concentration of nutrient elements in atmospheric aerosol, but also increased accompanied the increased rainfall, that was a positive correlation . The wet deposition flux was 62.9 mmol·m^-2·yr^-1 for N , 0.160 mmol·m^-2·yr^-1 for P , 1.91 mmol·m^-2·yr^-1 for Si in 2002 , 79.9 mmol·m^-2·yr^-1 for N , 0.305 mmol·m^-2·yr^-1 for P, 2.03 mmol·m^-2·yr^-1 for Si in 2003 . The proportion of nutrient elements in rainwater and seawater had obviously differences . The ratio of N/P was 393 in 2002 and 262 in 2003 which were much higher than the seawater (16) that would affect the phytoplankter growth by altering nutrient structure of the northwestern of Yellow Sea.In conclusion , concentration of ions and wet deposition fluxes had obviously increased these years in Qingdao. The contribution of ocean and terrene were both increasing . The increasing sandstorm was one reason , but most importantly ,the artificial effects were major problems . Heavy pollutants discharge made the atmospheric pollution loads increasing .