Metals In Particle Size Fractions Research Articles

Spatio-temporal distribution and source identification of heavy metals in particle size fractions of road dust from a typical industrial district.

Seasonally distribution and source apportionment of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in the road dust (RD) with the four size fraction sizes (<45μm, 45-63μm, 63-150μm and all sizes) in a typical industrial district were investigated using a combination of Moran index, Principal component analysis (PCA), and Positive matrix factorization (PMF). Results showed that from winter to summer, the proportion of the <45μm fraction dust in the total RD mass increased from 6.72% to 15.92% and that of 63-150μm dust particles decreased from 31.13% to 21.76%. The proportion of the enrichment factors (EF) at moderate pollution level in winter was higher than that in summer, especially for Cu, Cd and Pb. Further, the heavy metals were relatively enriched in particles 63-150μm in summer, while in particles <45μm in winter. Spatially, the distribution of heavy metal concentrations was more concentrated in the winter and showed low levels of regional diffusion. Based on the pollution mapping and PCA-PMF, the integrated source appointment showed that the industrial sources are the main sources of Zn, Cd and Pb, and their contributions are higher at a particle below 45μm in winter. The construction source significantly influenced Cr, Mn and Cu in summer with little diversity among particle size ranges. Therefore, the <45μm particles from industrial emission in winter is suggested to be under priority control. And the industrial transformation demonstration area in the Qingshan district should upgrade heavy pollution industry lines and strengthen the monitoring of soot emissions. Further, emissions from coal-fired enterprises should be restricted in winter. Besides, the attention should be paid to avoid urban traffic jams around construction projects and increase enclosed construction ratio.

Contamination characteristics of heavy metals in particle size fractions from street dust from an industrial city, Central China

In order to investigate the heavy metal pollution level and distribution characteristics in different particle sizes, and to evaluate the health risk, 42 street dust samples were collected in January 2015 from Huangshi, as an industrial city in Central China. The results analyzed by flame atomic absorption spectrometry (FAAS) showed that the average content of Cu, Pb, Zn, Cd, Mn, and Fe in the fine particle diameter (< 25 μm) was 1041.12, 361.64, 890.00, 14.43, 3178.52, and 61841.79 mg kg−1, respectively. Meanwhile, the average content of Cu, Pb, Zn, Cd, Mn, and Fe in the coarse particle diameter (25 < D < 75 μm) was 1628.54, 401.52, 593.16, 9.54, 5316.07, and 76765.37 mg kg−1, respectively. Compared with other cities, the heavy metal pollution of street dust in Huangshi was more serious. The results indicated that heavy metals were more easily enriched in fine grains street dust, except for Cu, Mn, and Fe. The heavy metal elements showed obvious spatial heterogeneity in different regions, and the interference from human sources was greater. Heavy metals in Huangshi street dust are generally at moderate or higher pollution levels (except Fe), of which Cu and Cd are the most seriously polluted. Multivariate statistical analysis shows that the heavy metals in fine-grained street dust mainly come from traffic/industrial mixed sources (74.5%) and industrial sources (25.5%); the heavy-grained street dust heavy metals mainly come from mixed traffic/industrial sources (55.1%) and soil source (44.9%). For non-carcinogenic heavy metals, mainly through the hand-mouth contact pathway into the human body, there are also no non-carcinogenic health risks in both hand-mouth ingestion and dermal contact. For carcinogenic heavy metals, Cd in street dust did not have carcinogenic risk.

Distribution, bioavailability, and leachability of heavy metals in soil particle size fractions of urban soils (northeastern China).

This study examines the distribution, mobility, and potential environmental risks of heavy metals in various particle size fractions of urban soils. Representative urban topsoils (ten) collected from Anshan, Liaoning (northeastern China), were separated into six particle size fractions and their heavy metal contents (Cr, Cu, Cd, Pb, and Zn) were determined. The bioaccessibility and leachability of heavy metals in particle size fractions were evaluated using the toxicity characteristic leaching procedure (TCLP) and ethylenediaminetetraacetic acid (EDTA) extraction, respectively. The results indicated that the contents of five heavy metals (Cd, Cr, Cu, Pb and Zn) in the size fractions increased with the decrease of particle size. The clay fraction of <2μm had the highest content of heavy metals, indicating that the clay fraction was polluted by heavy metals more seriously than the other size fractions in urban topsoils. Cr also concentrated in the coarse fraction of 2000-1000μm, indicating a lithogenic contribution. However, the dominant size fraction responsible for heavy metal accumulation appeared to belong to particle fraction of 50-2 μm. The lowest distribution factors (DFs) of heavy metals were recorded in the 2000- to 1000-μm size fraction, while the highest in the clay fraction. The DFs of heavy metals in the clay fraction followed Zn (3.22) > Cu (2.84) > Pb (2.61) > Cr (2.19) > Cd (2.05). The enrichment factor suggested that the enrichment degree of heavy metal increased with the decrease of the particle size, especially for Cd and Zn. The TCLP- and EDTA-extractable concentrations of heavy metals in the clay fraction were relatively higher than those in coarse particles. Cd bioavailability was higher in the clay fraction than in other fractions or whole soils. In contrast, Cr exhibits similar bioaccessibilities in the six size fractions of soils. The results suggested that fine particles were the main sources of potentially toxic metals in urban soils. The variation of heavy metals in various size fractions should be taken into account in environment assessments.

Metals in particle-size fractions of the soils of five European cities

Soils from Aveiro, Glasgow, Ljubljana, Sevilla and Torino have been investigated in view of their potential for translocation of potentially toxic elements (PTE) to the atmosphere. Soils were partitioned into five size fractions and Cr, Cu, Ni, Pb and Zn were measured in the fractions and the whole soil. All PTE concentrated in the <10 μm fraction. Cr and Ni concentrated also in the coarse fraction, indicating a lithogenic contribution. An accumulation factor (AF) was calculated for the <2 and <10 μm fraction. The AF values indicate that the accumulation in the finer fractions is higher where the overall contamination is lower. AF for Cr and Ni are particularly low in Glasgow and Torino. An inverse relationship was found between the AF of some metals and the percentage of <10 μm particles that could be of use in risk assessment or remediation practices.