Platinum pollution in road dusts, roadside soils, and tree barks in Seoul, Korea - PowerPoint PPT Presentation

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Platinum pollution in road dusts, roadside soils, and tree barks in Seoul, Korea

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  1. Suburbs of Seoul (control area)(2.3 ng/g) Km Road dust Tree bark Roadside soil Grinding into powder form Sieving into <75 μm (-200 mesh) 2 g sample + 21 ml HNO3 + 7 ml HCl 200 mg sample + 3 ml HNO3 + 0.5 ml HCl I. 60 ℃ for 30 min. Heating Microwave digestion II. 140 ℃ for 90 min. Pt ICP-MS Other elements ICP-OES Busy roads in Seoul (444 ng/g) Platinum pollution in road dusts, roadside soils, and tree barks in Seoul, Korea Hea-Youn Lee*, Hyo-Taek Chon** & Manfred Sager*** *Mine Reclamation Corporation, Seoul 110-727, Korea. **Department of Energy Resources Engineering, Seoul National University, Seoul 151-744, Korea. (E-mail : chon@snu.ac.kr) ***Austrian Agency for Health and Food Safety, A-1226 Vienna, Austria. Abstract This study presents the level of platinum(Pt) in road dusts, roadside soils and tree barks collected from various traffic volume urban roads in and around Seoul, the capital city of Korea, and represents the first detailed assessment of auto-catalyst derived Pt in Korea. The total area of Seoul is about 605 km² and its population was about 10.45 millions in 2008. In Seoul, 2.95 million motor vehicles were on register in 2008. The suburbs of Seoul, so called as Gyeonggi Province, is located surrounding Seoul. Road dust and roadside soil samples were collected from 31 sites of various traffic volumes in Seoul, and from 4 control sites in Gyeonggi Province for comparison. Tree bark samples were collected from 7 road sites in Seoul. The above samples were analyzed for Pt by inductively coupled plasma mass spectrometry(ICP-MS) and other heavy metals by inductively coupled plasma optical emission spectrometry (ICP-OES). Platinum levels in road dusts and roadside soils from Seoul were in the range of 3.8 - 444 ng/g(av. 115.0 ng/g), and 0.7 - 221 ng/g(av. 49.7 ng/g), respectively. On the other hand, platinum levels in the suburbs of Seoul were in the range of 2.3 - 5.2 ng/g(av. 3.9 ng/g) in road dusts, and 0.4 - 5.1 ng/g(av. 2.4 ng/g) in roadside soils. The highest Pt levels in road dusts (223, 331, 445 ng/g) were found from major roads with high traffic volume and the lowest levels (2.38, 3.50, 4.70, 5.20 ng/g) were found from the suburbs with low traffic volume. The remarkable difference of the average Pt level between heavy traffic roads (> 2 lanes; av. 132.2 ng/g) and light traffic roads (< 2 lanes; av. 22.8 ng/g) reflects that an important source of Pt in roadside environment is automobile catalytic converter, and that it indicates a tendency to increase Pt levels in road dusts along with traffic volume. High Pt level in road dust was found from the site of erratic stop-start driving condition. Platinum level in road dust around a vehicle crossing gate was 178 ng/g, which is higher than the average Pt level (132.2 ng/g) in heavy traffic road dusts. It is suggested that not only traffic volume but also driving style have a great influence on Pt levels in road dusts. Platinum level in tree barks ranged from 0.9 to 4.5 ng/g, indicating the existence of Pt-containing particulate matter in the urban atmosphere of Seoul. Road dusts with high Pt level were enriched in traffic related elements such as Cu, Cr, Mo, Sb, Ni, and Fe comparing with road dusts from control areas. The obtained results indicate that road dusts from the heavy traffic roads in Seoul contain high Pt and heavy metals polluted by traffic emission. Site description Pt levels in road dusts Pt levels in roadside soils (24 samples) • Seoul metropolitan city in Korea • The capital city of Korea • The total area : 605.52 km² • Population : 10,456,095 as of the 1/4 of 2008 • 2.95 million vehicles were on register in 2008 Lowest level Highest level Busy roads in Seoul (221.1 ng/g) Suburbs of Seoul (0.4 ng/g) Lowest level Highest level (34 samples) Analysis procedure Other elements in road dusts Control areas Roads with high Pt levels in Seoul Pt levels in tree barks (7 samples) Pt-containing particles are present in urban atmosphere →A possibility of inhalation and accumulation in human Control areas Roads with high Pt levels in Seoul Pt levels vs. Driving style Pt levels vs. Traffic volume There is a tendency to increase Pt levels in road dusts along with traffic volume In erratic stop-start driving conditions, catalytic converters are subjected to large temperature gradients which contributes to the breakdown process Cu, Cr, Mo, Sb, Ni, Fewere enriched in road dusts with high Pt levels in Seoul as compared with road dusts from control areas 178.3 ng/g Main source of Pt contaminationin roadside environment iscatalytic converter ! Traffic related elements : emitted from brake lining materials, fuel combustion process, etc.