Water solubility of metals in coarse PM and PM2.5 in typical urban environment in Hong Kong

Jiang, Sabrina Y.N.; Yang, Fenhuan; Chan, Ka Lok; Ning, Zhi

Water solubility of metals in coarse PM and PM2.5 in typical urban environment in Hong Kong

2014

Jiang, Sabrina Y.N. | Yang, Fenhuan | Chan, Ka Lok | Ning, Zhi

An investigation of abundance and solubility of metals in size–segregated particulate matter (PM) was conducted at a typical urban site during the winter between late 2011 and early 2012 in Kowloon Tong, Hong Kong. The samples were extracted by both strong acid and water, and fourteen elements including Al, Ca, Cd, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, V, and Zn were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP–OES) and Inductively Coupled Plasma Mass Spectrometry (ICP–MS). The metals in PM showed distinctly different profiles of their distribution between coarse particles (2.5μm<dp<10μm) and PM2.5 (dp<2.5μm). The upper continental crustal enrichment factors (CEFs) of the measured metals for two particle size fractions showed that CEFs for nine of fourteen metals in PM2.5 were higher than 10 while Cd, Pb, Zn, Mn and Cu were far above 100; whereas for coarse particles, the CEFs of most elements were lower than 10, except for Cd being higher than 100. Water and acid extractable fractions of coarse PM and PM2.5 were analyzed and compared to investigate the transition metals solubility. The water extractable fraction was found to be present mainly in the fine particles, whereas more of the coarse fraction mass remained as insoluble fraction. The results from this study demonstrated large variation of water solubility of metals in urban aerosols in different size fractions and highlighted solubility as an important metric for considering the relation between metals and adverse health effects in epidemiological and toxicological studies.

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