Current status of air pollution in urban area of Bangkok, Thailand

Abstract

The aerosol of urban 4-sites (Jankasem, Dindaeng, Somdet Chaopuraya and Ratburana) in Bangkok was collected by high volume air sampler at August, 2001 (wet season) and January, 2002 (dry season) . The concentrations of dry season to TSP, PM10, NO₂and SO₂, were two times as large as wet one due to wash out effect in wet season. Moreover, Ca²⁺and NH₄⁺concentrations dry season were higher than wet season in water soluble cations. The aerosol acidity was controlled by NO₃/nss-SO₄, this ratio (0.69) at dry season was greater than wet season (0.37) . On contrast, NH₄/Ca which controlled neutralization capacity in the aerosol, major control factor was Ca²⁺. In reflecting prevailing wind of Bangkok in both season, Cl/Na (equivalent) was close to composition sea-salt-particle (1.18) at wet season and far from dry one. At January 19 and 25 when both high NO₃^-and SO₄^2-concentration were detected with low visibility, since there were intensive traffic jams in Bangkok, after this events, relatively high concentration of C₂O₄^2-were detected in the aerosol. Among heavy metals, the concentration of Pb was extremely low and below WHO long term standard (0.5-1.0μg/m³) . TSP was strongly correlated with Mn, Fe, K and Ca. And these elements were major components of the soil. The concentration of V and Ni were low because there were no large oil-combustive stationary sources in this area. By the application of enrichment factor to the detected elements, Zn, Pb, NO₃-N, SO₄-S and TC in the aerosols were come from anthropogenic sources. The concentration of PAH was highest at Dindaeng where was intensive traffic density. Associated these facts, the concentration of total carbon (TC) was fluctuated from 20-30% of TSP and observed highest concentration at Dindaeng.