Ground-level Particulate Sulphate and Gaseous Sulphur Dioxide Downwind of an Aluminium Smelter

• Published in: Aerosol and Air Quality Research Vol. 21; no. 5; pp. 1 - 20+ap1-11-010
• Main Authors: Blanchard, Dane, Aherne, Julian
• Format: Journal Article
• Language: English
• Published: Taoyuan City 社團法人台灣氣膠研究學會 01.05.2021; Taiwan Association of Aerosol Research
• Subjects: Aerosols; Aluminum; Anthropogenic factors; Climate change; Emission; Emissions; Environmental health; Metallurgy; Oxidation; Pollutants; Samplers; Smelters; Sulfates; Sulfur; Sulfur dioxide; Vanadium; Wind; Pacific Ocean; Passive sampler; British Columbia; Atmospheric sulphur; Filter-pack
• ISSN: 1680-8584; 2071-1409
• DOI: 10.4209/aaqr.200528

Particulate sulphate (pSO_4^(2-)) is an atmospheric pollutant known to affect human/environmental health and global radiative-forcing. The Rio Tinto (RT) aluminium smelting facility in Kitimat, British Columbia, is the primary source of sulphur dioxide (SO_2) emissions to the surrounding Kitimat Valley, a relatively isolated and unpolluted region. A network of active two-stage filter-packs and passive-diffusive samplers was established between June 2017 to October 2018 with the objective to evaluate the spatiotemporal variation and relative contribution of pSO_4^(2-) to total anthropogenic atmospheric oxidized sulphur (SO_x = SO_2 + pSO_4^(2-)). Average pSO_4^(2-) across all sites (n = 9) was 0.41 μg m^(-3) (24-48 hour exposures) and ranged from 0.03 to 2.03 μg m^(-3). In contrast, average filter-pack SO_2 ranged from 0.11 to 8.9 μg m^(-3) (during the same exposure periods). The filter-pack pSO_4^(2-)/SO_x concentration ratio (F_s) increased downwind of the smelter, indicating that the relative concentration of pSO_4^(2-) increased with distance from the smelter. Furthermore, the increasing pSO_4^(2-)/vanadium (V) ratio (used as a tracer of smelter emissions) relative to distance confirmed particulate formation was occurring within the emission plume during the sampling period. Irrespective of in-plume aerosol formation, pSO_4^(2-) contributed a relatively minor fraction of total atmospheric SO_x within the emission plume (field campaign averages F_s ＜ 20%; pSO_4^(2-) ＜ 0.1 μg S m^(-3); SO_2 ＞ 1.0 μg S m^(-3)).