Particulate bound mercury Hg(p) concentrations, compositions and dry depositions study around mixed and agricultural (MA) sites

Abstract

TSP concentrations in ambient air and dry deposition were measured at an (agricultural) sampling site in Taiping. The TSP concentrations are compared with those in the other counties in Asia. Statistical differences between the TSP concentrations and dry depositions in Luliao district (mixed site) and Taiping district (agricultural site) are discussed. Ambient air particulate-bound mercury Hg(p) concentrations in TSP and dry depositions are analyzed and discussed. Mean concentrations and dry depositions of Hg(p) were tested at two characteristic sampling sites – Luliao (mixed) and Taiping (agricultural) districts. Finally, the measured ambient air particulate-bound mercury Hg(p) concentrations and dry depositions were compared with those in other regions of the world. TSP concentrations were highest in March at 49.7 (μg/m³) and lowest in June at 15.85 (μg/m³). Dry deposition was highest in March at 1336.41 (μg/m²*min) and lowest in June at 15.85 (μg/m²*min). The highest average dry depositions and TSP concentrations were measured in March. The particulate-bound mercury Hg(p) concentrations in TSP were higher at the Luliao sampling site (0.384 μg/m³) than at the Taiping (0.078 μg/m³) sampling site. The mean Hg (p) dry deposition was higher in Taiping (0.665 μg/m²*min) than in Luliao (0.387 μg/m²*min). The mean concentrations of TSP differed between Luliao (mixed) and Taiping (agriculture) sampling sites, but the mean dry depositions did not. The differences between TSP concentrations and dry depositions might have arisen from the fact that most of the particulate-bound mercury Hg(p) at the Taiping (agriculture) sampling site had natural sources while that at the Luliao (mixed) sampling site had anthropogenic sources. The average ratios of highest to lowest particulate concentrations exceeded seven in urban areas; exceeded 1.5 in areas of traffic, and approached (one OR unity OR 1) for all particulate sizes.

KEYWORD:

• TSP
• dry deposition
• T-test
• agriculture site
• Hg(p)

Acknowledgments

The authors gratefully acknowledge the National Science Council of the ROC (Taiwan) for financially supporting this work under project no 108-2221-E-241-006.