Author(s)

S. Pongpiachan, V. Surapipit, A. Ketratanakul, N. Wuttijak & A. Pongnoppa

Abstract

When air mass is flowing across the source area, it can lead to emissions and subsequently higher emissions of atmospheric concentrations of trace gases. It is well known that wind direction plays a significant role on atmospheric concentrations of persistent organic pollutants (POPs). While temperature and wind speed are obviously important parameters governing the atmospheric concentration of trace gases, these two parameters alone fail to entirely predict the atmospheric concentration of trace gases. Alternatively, wind direction may also be a controlling parameter for trace gas concentrations. Given that wind direction is measured as an angle (α) relative to true north (0), mean direction was determined by using trigonometric relations to determine the direction of the resultant of individual wind vectors. The emission source strength – wind direction relationship can be represented graphically by plotting R-value of (natural logarithm of partial pressure) vs against downwind angle (α) during the monitoring period. To apply this relationship, measured atmospheric concentrations must be expressed as partial pressures (P), which can be converted through the use of the ideal gas law with a temperature correction. The

Keywords

trace gases, wind direction, trigonometric, Mapthaput Industrial Estate, Thailand, risk analysis