Determination of Heavy Metal Distribution in PM₁₀During Asian Dust and Local Pollution Events Using Laser Induced Breakdown Spectroscopy (LIBS)

Abstract

Hourly concentrations of heavy metals in PM 10 samples were continuously measured using Laser Induced Breakdown Spectroscopy (LIBS) to determine the metal distribution among Asian Dust (AD) events, local pollution events, and nonevents. Quantification of metals was performed by establishing a calibration line between 24 h average data determined by the ICP-MS after filter sampling and LIBS intensity data. It was found that in AD and local pollution events, significant anthropogenic heavy metals, such as Pb, Cr, Ni, and Zn, were detected compared to a nonevent, and that crustal elements (e.g., Al, Ca, Mg) were more abundant in the AD events than those in a local pollution event or nonevent. The AD events were further classified into "nonpolluted AD" and "polluted AD" events, depending on the air mass transport pathways. During "polluted AD" events where the air mass passed over industrialized zones, both crustal (Al, Ca, Mg) and anthropogenic (Cr, Ni, Zn) metal elements simultaneously increased with time, suggesting that the AD particles could not only include crustal elements but also have a significant quantity of anthropogenic heavy metals. The concentration of anthropogenic heavy metals (Cr + Pb + Zn) was the highest in the AD3 event in order of AD3 (polluted) > AD1 (polluted) > local pollution > AD2 (nonpolluted). However, the PM 10 -weighted value (Cr + Pb + Zn/PM 10 ) was the highest in the local pollution event where concentrations of only anthropogenic heavy metals increased. Also, the hourly LIBS data was successfully used to discriminate metal contributions between AD events and local pollution events or among AD events by employing a chemometric method.

A critical review of recent progress in analytical laser-induced breakdown spectroscopy

“…The progress in this large field was reviewed by Hahn [52] a few years ago. Some noteworthy results of environmental LIBS aerosol analysis include development of methods for more efficient particle collection on a substrate [53], differentiation between gas-phase and particulate analytes [160], and a correlation study of heavy-metal concentrations in Asian dust and local pollution events [161].…”

Review of In-Situ Online LIBS Detection in the Atmospheric Environment

“…Kwak et al developed a LIBS experimental system with a particle collection substrate stage that could automatically move in a specific time interval. 51 The detection results of the PM in every time interval were averaged to obtain time-resolved compositional information about the PM. Zhang et al carried out research on the qualitative and quantitative detection of heavy metal elements in PM samples.…”

2013 Atomic spectrometry update—A review of advances in environmental analysis

“…Initial studies, using lter samples spiked with reference silica, kaolin and coal dust samples, and by undertaking measurements at the Si 288.16 nm emission line, suggested that this approach had potential as an end-of-shi screening tool. In the hourly monitoring 36 of metals (e.g., Al, Ca, Cr, Fe, Pb and Zn) in PM 10 particles during Asian dust pollution episodes, the particles were sampled through a PM 10 size-selective inlet, dried and focused as a spot onto a movable nylon lter. By moving a sample spot under a Nd:YAG laser it could be interrogated for their elemental composition.…”

“…Aer heating at 1450 C for 20 min, the blanks of 3.7 Â 10 À21 mole for 3 He and 1.1 Â 10 À15 mole for 4 He were an order of magnitude better than those of a conventional double vacuum furnace. Large accelerators are normally necessary to separate 36 Cl from its stable isobar 36 S but these measurements can now be performed with modern 5 MeV AMS instruments using gas stripping to produce the highest quality beams. A protocol 325 for the accurate determination of 36 Cl included ID for stable Cl measurement and separation from 36 S on a relatively small automated spectrometer using 30 MeV ions.…”