| With the rapid of urbanization and industrialization,urban heavy metal contamination has been widely concerned.Contamination and spatio-temporal characteristics,contamination sources and source apportionment methods,and risk assessment of heavy metals in urban soil and surface dust received particular attention.The spatial and temporal distribution of heavy metals in urban soil and surface dust is closely related to contamination sources,and industrial emission and traffic release are the important contributors.Thus,heavy metal contamination of soil and surface dust in industrial areas and urban roads has been concerned.Source apportionment was difficult in the heavy metal contamination study in urban environment due to the complexity of sources.Mathematical statistics and receptor models have been widely used,however,the lack of in-depth analysis of the applicability of the models affected the reliability of source apportionment results.Bioaccessibility of heavy metals has been included in health risk assessment,but the effect of chemical speciation on bioavailability is not clear.The main urban area of Jinan city was the research area in this study.Concentration of 10 metals in the surface dust of the main road(spring 2020,winter 2020 and winter 2023)and residential areas were analyzed,and those in the roadside and residential soil were used for comparison.Contamination level and spatio-temporal variation of metals were studied.Source contributions of metals were discussed.The effects of the chemical speciation of metals on bioaccessibility were analyzed,and the health risks of Cd,Cr,Cu,Ni,Pb,Sb and Zn in soil and surface dust were assessed.The main conclusions are as follows:(1)Mean concentration of metals in soil and surface dust in Jinan were ranked as follows:Al>Fe>Zn>Cr>Cu>Pb>Ni>Sn>Sb>Cd.Mean concentration of Zn,Cr,Cu,Pb,Sn,Sb and Cd in dust and soil were 2.1-13.2 and 1.3-6.6 times higher than the background values in Jinan,respectively.Based on the enrichment factor(EF),contamination of metal in surface dust was higher than that in soil.In surface dust,Sn,Pb and Cr are moderately contaminated,while Cd and Zn are significantly contaminated.Sb in road dust and Cu in residential dust are significant contaminated.Other metals in road and residential dust were no-low contaminated.Cd in soil,and Sb,Zn in roadside soil were moderately contaminated,other metals in roadside and residential soil were no-low contaminated.Comprehensive contamination of metals was ranked as follows: residential dust>road dust>roadside soil>residential soil,while those in road dust in different period was: winter of 2023>winter in 2020>spring in 2020.(2)The main difference of chemical speciation of metals between soil and surface dust was occurred in acid-soluble phase(F1),reducible phase(F2)and oxidizable phase(F3).Concentrations of the F1,F2 and F3 of metals in dust were higher than those in soil.In surface dust,Cd and Zn were mostly present in F1 and F2,Pb was strongly associated with F2,F3 and residual phase(F4),Cr and Ni are mainly present in F4,and Cu was predominantly present in F3 and F4.In soil,Cd was mostly present in F1 and F2,Cr,Cu and Ni was predominantly present in F4,and Pb was strongly associated with F2.Zn was mostly present in F2 in roadside soil and present in F4 in residential soil.Bioaccessible quantity of metals in surface dust was higher than that in soil.In surface dust,except for Cu,bioaccessible quantity of metals in residential dust during gastrin and intestinal stage were higher than road dust.Bioaccessible quantity of Cd,Cu,Ni and Zn in roadside soil during gastrin and intestinal stage were higher than residential soil.In the gastrin stage,bioaccessibility of metals in roadside and residential soil,and residential dust were ranked as follows: Cd>Zn>Pb>Cu>Ni>Cr,and in road dust was ranked as follows: Zn>Cd>Pb>Cu>Ni>Cr.In the intestinal stage,bioaccessibility of metals in road and residential dust,and roadside soil were ranked as follows: Cu>Cd>Ni>Zn>Cr>Pb,and in residential soil was ranked as follows:Cd>Cu>Ni>Zn>Cr>Pb.(3)Based on positive matrix factorization(PMF)factor analysis with nonnegative constraints(FA-NNC),source apportionment results of metals in soil were similar,but those in surface dust were inconsistent.Combining Pb isotopes and traffic factors,FA-NNC model results are more reliable.According to FA-NNC results,non-exhaust traffic source is the greatest contributor(28.4-44.7%)of metal in surface dust.Metals in surface dust were mainly affected by natural,industrial and non-exhaust traffic source,in addition,metals in residential dust were affected by construction source.Chromium and Ni were mainly from industrial sources,exhibiting a southward decreasing trend.Cadmium,Cu,Pb,Sb,Sn and Zn were mainly from non-exhaust traffic sources,exhibited higher values in the central area.Copper and Pb contamination in residential dust was mainly attributable to construction sources and exhibited high value in the northern part.Differently,in soil,the contribution of industrial-traffic source to metals was close to that of non-exhaust traffic source.Cadmium,Cr and Zn in the roadside soil and Cr,Cu and Ni in residential soil were mainly from the industry-traffic source,exhibiting a southward decreasing trend.Antimony and Sn in the roadside soil and Cd and Pb in residential soil were mainly from the non-exhaust traffic source,showing higher values in the central of the city.In soil and dust,Al and Fe were mainly from natural sources.(4)In terms of health risk,Cr was the biggest risk metal,and industrial source was the largest contributor to health risk.Based on USEPA health risk assessment and Monte Carlo simulation results,the non-carcinogenic and carcinogenic risk of metals in surface dust was higher than those in soil,while the risk in residential dust was greater than that in road dust.Combining bioaccessibility of metals,the non-carcinogenic and carcinogenic risk for children and adults were below the threshold.In soil and dust,Cr and Pb were the main risk metals during gastric stage,and Cr was the biggest risk metal during intestinal stage.According to multivariate statistical analysis and random forest simulation model,EF and F2 of metals had the most obvious effect on bioaccessibility of metals in soil and surface dust.F3 of Cu and Pb in soil,F1 and sample properties in surface dust were also had high importance on bioaccessibility of corresponding metals. |
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