| Summary: | 碩士 === 嘉南藥理大學 === 環境工程與科學系 === 102 === The concentrations of metals (Cu, Pb, Zn, Cr, and Ni) in street dust samples collected from 18 sites located in and around urban areas in Kaohsiung city, Taiwan, from October 2012 to April 2013, were determined by flame atomic absorption spectrometry (FAAS) after the modified sequential extraction procedure. Particles of street dust can be divided into four groups with diameter of < 0.074, 0.074-0.297, 0.297-0.5, and 0.5-2.0 mm, which were collected using a three-stage vibration shaker. Heavy metals in street dust were also fractionated into exchangeable, bound to carbonates, bound to Mn-oxides, bound to Fe-oxides, and bound to organic matters.
The highest concentrations of heavy metals can be found in finest particle fraction (< 0.074mm), and decreased with increase of particle sizes. Over 90% of Cu bound with organic matters. Pb existed in five fractions with mean percentage. Zn primarily bound to carbonate fraction. Cr primarily bound to Fe-oxides fraction about 65%. Ni primarily bound to Fe-oxides, next bound to organic matters. The results of the analyses were used to determine major sources and magnitude of heavy metal pollution, and were compared with the background values. The highest concentration levels of zinc (Zn), lead (Pb), copper (Cu), chromium (Cr), and nickel (Ni) were found to be 1052, 732, 301, 50, and 23 mg kg-1, respectively. High concentrations of heavy metals were detected in south urban and close proximity to emission sources such as industrial and shipbuilding areas. Enrichment factors (EFs) as the criteria for examining the impact of the anthropogenic emission sources of heavy metals were calculated with background levels. The highest enriched elements were Cu, Pb, and Zn, about 55, 10 and 8, respectively in the street dust samples. EF values revealed that the sampling area was mainly influenced from four pollution areas, namely, Dafa, Kaohsiung Linhai, and Ren Da industrial parks, and shipbuilding areas.
|
|---|
