Dry, wet depositions for ambient air nitrate, sulfate, and chloride ionic species at mixed (traffic, commercial, and residential) sampling sites in Central Taiwan

Abstract

This research was focused on the measurements of ambient air pollutants species (Cl⁻, NO₃⁻, and SO₄²⁻) concentrations of wet and dry depositions by using PS-1 (TSP), dry depositions plate and wet depositions tub at mixed (traffic, commercial, and residential) sampling sites. Lu-Liao, characterized by traffic, commercial and residential sites, was selected as the dry deposition measurement site. Hungkuang University, characterized by a traffic site, was selected as the wet deposition collection site. At the Luliao site, the results indicated that the average ionic species (Cl⁻, NO₃⁻, and SO₄²⁻) concentrations were 12.86, 25.58, and 18.37 μg/m³, respectively, in winter and 2.94, 11.37, and 14.09 μg/m³, respectively in spring. The average ionic species (Cl⁻, NO₃⁻, and SO₄²⁻) dry depositions were 284.43, 1808.50, and 412.93 μg/m² min, respectively, in winter and 147.66, 109.59, and 415.44 μg/m² min, respectively, in spring. As for the monthly Cl⁻, NO₃⁻, and SO₄²⁻ volume weighted mean (VWM) concentrations at the Hungkuang site, the results for January were 5.64, 4.41, and 10.13 mg/L, for May were 0.45, 1.98, and 2.09 mg/L, for June were 0.76, 1.39, and 2.46 mg/L, and for July were 1.83, 2.97, and 5.84 mg/L. The monthly Cl⁻, NO₃⁻, and SO₄²⁻ Fw (Flux_{wet deposition}) at the same site were 355.41, 277.63, and 638.15 mg/m² month, respectively, for January; 17.01, 99.03, and 362.05 mg/m² month, respectively, for May; 99.03, 181.18, and 319.45 mg/m² month, respectively, for June; and 362.05, 587.86, and 1156.49 mg/m² month, respectively, for July. SO₄²⁻ had the highest VWM and Fw values when compared with the other ionic species, Cl⁻ and NO₃⁻. The highest VWM values for all ionic species (Cl⁻, NO₃⁻, and SO₄²⁻) all occurred in winter.

Keywords:

• TSP
• dry depositions
• wet depositions
• ionic species

Additional information

Funding

The authors gratefully acknowledge the National Science Council of the ROC (Taiwan) for financially supporting this work under project no. 106-2221-E-241-006.