| บทคัดย่อ(English) |
The objective of this research was to monitor the acid deposition in the western region of Thailand. The province of Nakhonpathom was chosen as a monitoring site. The acid depositions were divided into 2 categories, namely wet and dry depositions which was collected by using the wet only collector and the filter packs, respectively. The sampling period was from January 2001 to February 2002. The rainwater samples were analyzed for pH, conductivity, sulfate, nitrate, chloride, calcium, magnesium, sodium, potassium and ammonium. The results of wet deposition reveal that the pH mean value was 6.35 and the conductivity mean value was 16.47 microsemens per centimeter. When considering the average concentrations of both anions and cations contained in rainwater, ammonium gave the highest amount of 86.78 microequivalent per liter. In addition, ammonium was also found at the highest deposition amount of 5.17 milligrams per square meter per year. The experiment also reveal that the mole ratio of nitrate to non sea salt sulphate was 1.90, indicating that the acidity of rainwater caused by nitric acid rather than sulfuric acid. In the case of dry deposition, the aerosol sulfate was found at the highest concentration of 1,854 nanograms per cubicmeter. The gas concentrations in the atmosphere ranking from high to low were ammonia, hydrogen chloride, sulfurdioxide and nitric acid, respectively. The study on the ratio of wet to dry acid depositions shows that the quantity of the dry acid deposition was about equal to the amount of the wet acid deposition. The percentage of the dry acid deposition was 57.71% for sulfur and 58.77% for nitrogen. |
