2009～2010년 제주지역 강우성분의 계절 특성

Abstract

The collection of rainwater samples was made at Jeju area during 2009-2010, and the major ionic species were analyzed. In the comparison of ion balance, conductivity, and acid fraction for the validation of analytical data, the correlation coefficients were within the range of 0.966∼0.990, showing a good linear relationship. The volume-weighted mean pH and electric conductivity were 4.9 and 17.8 μS/cm, respectively, at the Jeju area. The volume-weighted mean concentrations of ionic species in rainwater were in the order of Cl->Na+>nss-SO42->NH4+>NO3->Mg2+>H+>nss-Ca2+>HCOO->K+>PO43->CH3COO->NO2->F->HCO3->CH3SO3-. In addition, the elemental species showed concentrations with the order of Ca>Al>Pb>Ni>Fe>Ba>Ti>Mn>Sr>V?Cr>Mo>Co?Cd. The ionic strength of rainwater was 0.26±0.21mM during the study period, however it was decreased to 0.09±0.08 mM for the rainy season. The composition ratio of ionic species were 50.1% for the marine sources (Na+, Mg2+, Cl-), 30.9% for the anthropogenic sources (NH4+, nss-SO42-, NO3-), and 4.7% for the soil source (nss-Ca2+), beside 3.1% for organic acids (HCOO-, CH3COO-). From the seasonal comparison, the concentrations of NO3-, nss-Ca2+, and nss-SO42- increased in winter and spring seasons, indicating a reasonable possibility of long range transport from China. The correlation coefficient between Na+ and Cl- was 0.98, indicating an introduction of sea salts to the rainwater in Jeju area. Similarly, the high correlation coefficients of NO3-, nss-SO42-, and NH4+ indicate the existence of (NH4)2SO4 and (NH4)NO3, neutralizing the acidic rainwater species each other. The seasonal comparison of the acidification by nss-SO42- and NO3- anions showed 41.2～64.8% and 24.2～40.9%, respectively, and the acidification by organic acids showed 7.8～17.9 %. The seasonal free acidity was in the range of 22.0%～38.5%. The factor analysis of ionic components showed anthropogenic (24.0%)>sea salt (22.7%)>biogenic (14.8%)>soil (9.1%) at Jeju area. The backward trajectory analysis for the rainwater event days having high nss-SO42- and NO3- concentrations has showed as from China continent >Korea peninsula>East Sea>The North Pacific, indicating high influx of air pollutants from China into Jeju area.