Determination of source and assessment of contamination of potentially toxic elements mineral dusts of the Chadormalu Iron Mine, Bafq, Northeast of Yazd

Document Type : Research Article

Authors

Shiva Mehrabani ¹

Mohammad Maanijou ²

Afshin Qishlaqi ³

Yoriko Yokoo ⁴

¹ Ph.D. Student, Department of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran

² Professor, Department of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran

³ Assistant Professor, Department of Environmental Geology and Hydrology, Faculty of Earth Science, Shahrood University of Technology, Shahrood, Iran

⁴ Assistant Professor, Department of Environmental Systems Science, Faculty of Science and Engineering, Doshisha University, Kyoto- shi, Kyoto, Japan

10.22067/econg.2025.1141

Abstract

This study evaluates the concentration and source of potentially toxic elements in thirteen samples of in-situ dust collected from the Chadormalu iron mine, located 180 km northeast of Yazd city. Various geochemical indices including the geoaccumulation index, potential ecological risk index, the nemerow integrated pollution index, enrichment index and health risk were applied to assess the level of pollution in the mineral dust. Based on the I_geo index, the studied samples are classified as the severely polluted with elements such as Cr, Mn, Co, ni, Cu, Zn, As, Sn, Pb and V. They also exhibit moderate to severe contamination with respect to Mo. The potential ecological risk index of the element arsenic falls into the extremely high-risk category. The elements Mo, Cu, Zn, As, Sn and V are classified as severely polluted based on the integrated pollution index (NIPI), while the metals Pb, Ni and Co are categorized as moderately polluted. The enrichment index of the dust samples indicates the minimal enrichment for the studied elements. Based on the health risk assessment data, As and Cr exhibited the highest hazard quotient (HQ) values through the ingestion pathway. The non-carcinogenic risk associated with all the studied elements, when inhalation and dermal contact, was estimated to be less than 1. Consequently, individuals experience no adverse health effects. The risk of carcinogenicity exists for adults and children through ingestion of arsenic and for children through ingestion of chromium. Principal component analysis (PCA) revealed that the elements Co, Ni, Mo, V, and Sn have geogenic origins, while other elements are influenced by anthropogenic sources, including mining and processing activities.
 
Introduction
Mining and mineral processing are often associated with the release of toxic dust and effluents from tailings dams and metallurgical slag. Dust particles emitted during mining and mineral processing operations directly affect human health by being ingested or inhaled. The Chadormalu iron mine, situated 180 km northeast Yazd, is the largest iron deposit in Central Iran and part of the Bafq-Saghand metallogenic province. The sources of mineral dust production in the Chadormalu mine include the explosion sites surrounding the mine, the crusher, the tailings silo, the reclaimer, and the mineral dust emanating from the dry surface of the tailing dams. The aims of the present study to investigate the source and determine the contamination of potentially toxic elements (PTEs) in mineral dust and its impact on human health.
 
Materials and methods
To assess the PTEs, thirteen mineral dust samples were collected from various locations within the Chadormalu mine using plastic brushes and a dustpan in December 2023. The samples dried at room temperature and then passed a 2-mm sieve to eliminate roots, debris and stones. To determine the concentration of elements, sample of powdered material subsampled to 230- mesh sieve by an agate miller. Approximately, 0.5 gr of prepared sample digested in a mixture of 2 ml of HF (40%), 2 ml of HNO₃ (65%), and 6 ml of HCl (37%), following the standard method (DIN EN 13656: 2021-07), and subsequently, the elemental concentrations were determined using an Agilent 7850 ICP-MS instrument at the Eurofins Umwelt Ost GmbH laboratory, Freiberg, Germany. Quality control of the samples was performed using certified reference materials (CRMs) to measure accuracy, blank samples to assess contamination, and replicate samples to assess precision.
 
Results and discussion
The average concentrations of elements (mg/kg) in the mineral dust samples follow this order: Mn > V > Ni > Zn > Cu > As > Cr > Co > Pb > Sn > Mo. To determine the level of pollution, the geoaccumulation index (I_geo) was determined as fallow (Müller, 1969):
 
Where C_n and B_n represent the concentrations of elements in the sample and reference element (upper crust content), respectively. Based on the geoaccumulation index results, the elements Cr, Mn, Co, Ni, Cu, Zn, As, Pb and V are considered very strong polluted. The enrichment factor (EF) is expressed using the following equation (Liu et al., 2014), considering Fe as the reference element:
The C_i and C_r values refer to the element concentrations in the sample and reference material. The results indicates the minimal enrichment for the studied elements.
The ecological risk index (RI) is obtained by the follows (Zhang et al., 2018):
Where  and  are the ecological risk index and toxicity index of elements,  and  are the elements measured in the sample and reference material, respectively. On the basis of the results, the  values of elements Cr, Mn, Ni, Cu, Pb, V and Zn are considered low ecological risk at all mineral dust sampling stations. However, arsenic exhibits a moderate ecological risk in the study area. The RI value indicated the highest level of pollution and potential ecological risk at station FD8.
Sawut et al. (2018) defined the Integrated Pollution Index of Nemerow (NIPI) as follows:
That P_i is the single-factor pollution index for each element. The NIPI values indicated that Cu, Zn, As, Mo, Sn and V in the mineral dust samples belong to the heavy pollution class, while Co, Ni and Pb belong to the moderate pollution categories. Additionally, the element Cr classified as clean, while Mn classified as slightly polluted. 
In this study, health risk assessment for both adults and children were conducted based on inhalation, ingestion and dermal contact with PTEs present in mineral dust. The calculations were performed by the following relationship (USEPA, 1997):
 
The non-carcinogenic risks associated with elements are determined using the following equation (Hossen et al., 2021):
Where HQ is the hazard quotient to assess the non- carcinogenic hazard and RfD is the reference dose value (mg/kg/day). The hazard index (HI) is the cumulative sum of hazard quotient (HQ) values used to evaluate the overall non-carcinogenic risk posed by multiple toxicants (Hossen et al., 2021):
If HQ, HI < 1, indicates the absence of non-carcinogenic effects, while if HQ, HI > 1, it suggests the presence of non-carcinogenic effects. The health risk assessment and HQ values ​​indicate that the non-carcinogenic risk of the potentially toxic elements Ni, Cu, Zn, and Pb for adults and children is less than 1, indicating that there is a carcinogenic risk associated with these PTEs in the study area. Based on the HI values, both adults and children face a non-carcinogenic health risk when ingested occurs. The health risk assessment reveals that the non-carcinogenic risk is higher in children compared to adults. Arsenic emerges as the main risk factor for both age groups. The ingestion of As for children and adult, as well as Cr for children is associated with carcinogenic risks.
 
Conclusion
This study assessed the contamination of mineral dust with PTEs, determined the source of contamination and evaluated the health risks associated with the Chadormalu iron mine. The study of the concentration of total toxic elements revealed that the average concentration of all elements except for Cr and Mn is more than the concentration of metals found in the upper crust content. Non-carcinogenic risk of elements is higher in children than in adults, with As being the primary risk factor. The health risk assessment reveals that ingestion is the most important pathway for PTEs exposure. The results of calculating pollution indicators in the study area revealed that the main source of PTEs pollution is the mineralization of natural iron ore and mineral processing. These activities pose significant risks to human health and the environment.
 
Acknowledgment
We are grateful to the Chadormalu Industrial and Mining Company, particularly Mr. Mahmoudi, for their cooperation and Mr Meinhold (TU Bergakademie Freiberg, Germany) for providing the geochemical data. The authors express their sincere gratitude to the reviewer of Journal of Economic Geology for their valuable and insightful comments.

Keywords

Potentially toxic elements

mineral dust

Chadormalu Mine

Bafq

---

References

Adamu, C.I., Nganje, T.N. and Edet, A.E., 2015. Major and trace elements pollution of sediments   associated with abandoned barite mines in parts of Oban massif and Mamfe embayment, SE Nigeria. Journal of Geochemical Exploration, 151: 17–33. https://doi.org/10.1016/j.gexplo.2014.12.010

Baishan, K., Wang, X., Huang, X. and Eziz, M., 2023. Health Risk Assessment and Source Analysis of Toxic Element Pollution In Cultivated Soils of the Weigan and Kuqa Rivers Oasis in Xinjiang, China. Polish. Journal of Environmental studies, 32(4): 3501–3514. https://doi.org/ https://doi.org/10.15244/pjoes/166167

Banza, C.L.N., Nawrot, T.S., Haufroid, V., Decrée, S., De Putter, T., Smolders, E., Kabyla, B.I., Luboya, O.N., Ilunga, A.N., Mtombo, A.M. and Nemery, B., 2009. High human exposure to cobalt and other metals in Katanga, a mining area of the Democratic Republic of Congo. Environmental Research, 109(6): 745–752. https://doi.org/10.1016/j.envres.2009.04.012

 Barton, M.D., 2014. Iron oxide (Cu-Au-REE-P-Ag-U-Co) systems. Treatise on Geochemistry (Second Edition), V. 13, pp. 515-541. http://dx.doi.org/10.1016/B978-0-08-095975-7.01123-2

Boumaza, B., Kechiched, R. and Chekushina, T.V., 2021. Trace metal elements in phosphate rock wastes from the Djebel Onk mining area (Tébessa, eastern Algeria): A geochemical study and environmental implications. Applied Geochemistry, 127: 104910. https://doi.org/10.1016/j.apgeochem.2021.104910

Chau, N., Benamghar, L., Pham, Q.T., Teculescu, D., Rebstock, E. and Mur, J.M., 1993. Mortality of iron miners in Lorraine (France): Relations between lung function and respiratory symptoms and subsequent mortality. British Journal of Industrial Medicine, 50(11): 1017–1031. https://doi.org/10.1136/oem.50.11.1017

Chen, S.Y., Hayes, R.B., Liang, S.R., Li, Q.G., Stewart, P.A. and Blair, A., 1990. Mortality experience of haematite mine workers in China. British Journal of Industrial Medicine, 47(3): 175–181. https://doi.org/10.1136/oem.47.3.175

Dabiri, R., Bakhshi Mazdeh, M. and Mollai, H., 2017. Heavy metal pollution and identifcation of their sources in soil over Sangan iron-mining region, NE Iran. Journal of Mining and Environment, 8(2): 277–289.  https://doi.org/10.22044/jme.2016.820

Daliran, F., 2002. Kiruna-type iron oxide-apatite ores and apatitites of the Bafq district, Iran, with an emphasis on the REE geochemistry of their apatites. In: T.M. Porter, (Editor), Hydrothermal Iron Oxide Copper-Gold and Related Deposits: A Global Perspective, vol. 2. PGC Publishing, Adelaide, pp. 303–320. Retrieved June 23, 2025 from https://www.geokniga.org/bookfiles/geokniga-19bafq-district-irandaliran.pdf

Daliran, F., Stosch, H.-G., Williams, P.J., Jamali, H. and Dorri, M.B., 2010. Early Cambrian iron oxide-apatite-REE (U) deposits of the Bafq district, East-Central Iran. In: Co. Louise and M. Hamid (Editors), Exploring for Iron Oxide Copper-Gold (Ag-Bi-Co-U) Deposits: Examples from Canada and Global Analogues, pp. 147– 160. Retrieved June 23, 2025 from https://www.scirp.org/reference/referencespapers?referenceid=1942458

Dou, Y., Li, J., Zhao, J., Hu, B. and Yang, S., 2013. Distribution, enrichment and source of heavy metals in surface sediments of the eastern Beibu Bay, South China Sea. Marin Pollution Bulletin, 67‌(1–2): 137–145. https://doi.org/10.1016/j.marpolbul.2012.11.022

Eby, G.N., 2004. Principles of environmental geochemistry. Brooks/Cole, Australia, 514 pp.

Ettler, V., Cihlová, M., Jarošíková, A., Mihaljevič, M., Drahota, P., Kříbek, B., Vaněk, A., Penížek, V., Sracek, O. and Klementová, M., Engel, Z., Kamona, F. and Mapani, B., 2019. Oral bioaccessibility of metal (loid) s in dust materials from mining areas of northern Namibia. Environment International. 124: 205–215. https://doi.org/10.1016/j.envint.2018.12.027

Garcia, J.H., Li, W.W., Arimoto, R., Qkarasinski, R., Greenllee, J. and Walton, J., 2004. Characterization and implication of potential fugitive dust sources in the Paso del Norte region. Science of the Total Environment, 325(1–3): 95–112. https://doi.org/10.1016/j.scitotenv.2003.11.011

Haghipour, A., 1977. Geological map of Posht-eBadam, Scale 1:250,000. Geological Survey of Iran.

Hakanson, L., 1980. An ecological risk index for aquatic pollution control: a sedimentological approach. Water Research, 14(8): 975–1001. https://doi.org/10.1016/0043-1354(80)90143-8

Heidarian, H., Alirezaei, S. and Lentz, D.R., 2017. Chadormalu Kiruna-type magnetite-apatite deposit, Bafq district, Iran: Insights into hydrothermal alteration and petrogenesis from geochemical, fluid inclusion, and sulfur isotope data. Ore Geology Reviews. 83: 43–62. http://dx.doi.org/10.1016/j.oregeorev.2016.11.031

Hini, G., Eziz, M., Wang, W., Ili, A. and Li, X., 2020. Spatial distribution, contamination levels, sources, and potential health risk assessment of trace elements in street dusts of Urumqi city, NW China. Human and Ecological Risk Assessment: An International Journal‌, 26‌(8): 2112–2128. https://doi.org/10.1080/10807039.2019.1651629

Hossen, M.A., Chowdhury, A.I.H., Mullick, M.R.A. and Hoque, A., 2021. Heavy metal pollution status and health risk assessment vicinity to Barapukuria coal mine area of Bangladesh. Environmental Nanotechnology Monitoring & Management, 16: 100469. https://doi.org/10.1016/j.enmm.2021.100469

Huang, B., Long, J., Liao, H., Liu, L., Li, J., Zhang, J., Li, Y., Wang, X. and Yang, R., 2019. Characteristics of Bacterial Community and Function in Paddy Soil Profile around Antimony Mine and Its Response to Antimony and Arsenic Contamination. International Journal of Environmental Research and Public Health, 16(24): 4883.   https://doi.org/10.3390/ijerph16244883

Kani Kavan Shargh Consulting Engineers Company, 2021. Engineering services on mining observation and operation of Chadormalu Iron Ore Mine. Chadormalu Mining and Industrial Company. Project No, 1482.

Kaufman, L. and Rousseeuw, P.J., 1990. Finding Groups in Data. An Introduction to Cluster Analysis. John Wiley and Sons, Inc., New York. 342 pp. https://doi.org/10.1002/9780470316801

 Kaufman, L. and Rousseeuw, P.J., 2005. Finding Groups in Data: An Introduction to Cluster Analysis. John Wiley and Sons, Inc., New York. 368 pp. http://dx.doi.org/10.1002/9780470316801.ch1

Khelifi, F. Caporale, A.G., Hamed, Y. and Adamo, P., 2021. Bioaccessibility of potentially toxic metals in soil, sediments and tailings from a North Africa phosphate-mining area: Insight into human health risk assessment. Journal of Environmental Managment, 279: 111634. https://doi.org/10.1016/j.jenvman.2020.111634

Kříbek, B., Majer, V., Pašava, J., Kamona, F., Mapani, B., Keder, J. and Ettler, V., 2014. Contamination of soils with dust fallout from the tailings dam at the Rosh Pinah Area, Namibia: Regional assessment, dust dispersion modeling and environmental consequences. Journal of Geochemical Exploration, 144(Part C): 391–408. https://doi.org/10.1016/j.gexplo.2014.01.010

Liu, E., Yan, T., Birch, G. and Zhu, Y., 2014. Pollution and health risk of potentially toxic metals in urban road dust in Nanjing, a mega-city of China. Science of the Total Environment, 476–477: 522–531. https://doi.org/10.1016/j.scitotenv.2014.01.055

Loska, K. and Wiechuya, D., 2003. Application of principle component analysis for the estimation of source of heavy metal contamination in surface sediments from the Rybnik Reservoir. Chemosphere, 51(8): 723–33. http://dx.doi.org/10.1016/S0045-6535(03)00187-5

Moghtaderi, A., 2006. Geology and geochemistry of Chadormalu iron mine, southeast of Yazd, northeast of Bafq. Ph.D. Thesis, Shiraz University, Shiraz, Iran, 346 pp.

Müller, G., 1969. Index of geoaccumulation in sediments of the Rhine River. GeoJournal 2‌(3): 108–118. Retrieved June 23, 2025 from https://www.researchgate.net/publication/30306 0644_Index_of_geoaccumulation_in_sediments _of_the_Rhine_River

Müller, G., 1979. Schwermetalle in den Sedimenten des Rheins-Veränderungen seit 1971. Umschau, 79: 778–783. Retrieved June 23, 2025 from https://www.scirp.org/reference/ReferencesPapers?ReferenceID=792349

Niencheski, L.F., Windom, H.L. and Smith, R., 1994. Distribution of particulate trace metal in Patos Lagoon Estuary (Brazil). Marine Pollution Bulletin, 28(2): 96–102. http://dx.doi.org/10.1016/0025-326X(94)90545-2

NISCO., 1980. Result of search and valuation works at magnetic anomalies of the Bafq iron ore region during 1976-1979. National Iranian Steel Corporation, Iran, Unpublished Report, 260 pp.

Plumlee, G.S., Morman, S. A. and Ziegler, T.L., 2006. The toxicological geochemistry of earth materials: An Environ Geochem Health 123 overview of processes and the interdisciplinary methods used to understand them. Reviews in Mineralogy and Geochemistry, 64(1): 5–57. https://doi.org/10.2138/rmg.2006.64.2

Ramezani, J., 1997. Regional geology, geochronology and geochemistry of the igneous and metamorphic rock suites of the Saghand Area, central Iran: Unpublished Ph.D. Thesis, St. Louis, Missouri, Washington University, 416 pp.

Ramezani, J. and Tucker, R.D., 2003. The Saghand region, Central Iran: U-Pb geochronology, petrogenesis and implications for Gondwana tectonics. American Journal of Science, 303(3): 622–665. http://dx.doi.org/10.2475/ajs.303.7.622

Reimann, C. and DeCaritat, P., 2000. Intrinsic flaws of element enrichment factor (EFs) in environmental geochemistry. Environmental Science and Technology, 34(24): 5084–5091. https://doi.org/10.1021/es001339o

Reimann, C., Filzmoser, P. and Garrett, R.G., 2002. Factor analysis applied to regional geochemical data: problems and possibilities. Applied Geochemistry, 17(3): 185–206. https://doi.org/10.1016/S0883-2927(01)00066-X

Rudnick, R.L. and Gao, S., 2003. Composition of the continental crust. Treatise on Geochemistry, 3: 1–64.  http://doi.org/10.1016/B0-08-043751-6/03016-4 

Rusk, B., Oliver, N., Cleverley J., Blenkinsop, T., Zhang, D., Williams, P. and Habermann, P., 2010. Physical and chemical characteristics of the Ernest Henry iron oxide copper gold deposit, Australia; implications for IOGC genesis. Global Perspective Series, 3. PGC Publishing, Linden Park, SA, Australia, pp. 201–218. Retrieved June 23, 2025 frpm  https://researchonline.jcu.edu.au/18884

Sawut, R., Kasim, N., Maihemuti, B., Hu, L., Abliz, A., Abdujappar, A. and Kurban, M., 2018. Pollution Characteristics and Health Risk Assessment of Heavy Metals in the Vegetable Bases of Northwest China. Science of the Total Environment, 642: 864–878. https://doi.org/10.1016/j.scitotenv.2018.06.034

Singh, G., Pal, A. and Khoiyanbam, R.S., 2009. Impact of mining on human health in and around Jhansi, Bundelkhand region of Uttar Pradesh, India. Journal of Ecophysiology and Occupational Health, 9(1): 47–54. Retrieved June 23, 2025 from https://www.researchgate.net/publication/364958597

Smolders, E., Roels, L., Kuhangana, T.C., Coorevits, K., Vassilieva, E., Nemery, B. and Lubaba Nkulu, C.B., 2019. Unprecedentedly high dust ingestion estimates for the general population in a mining district of DR Congo. Environmental Science and Technology, 53(13): 7851–7858. https://doi.org/10.1021/acs.est.9b01973

Soltani, N., 2017. Medical Geology and Environmental Impact Associated with Mining and Mineral Processing in Gol-E-Gohar Iron Mine, Sirjan. Ph.D. Thesis, Shiraz University, Shiraz, Iran, 246 pp.

Stöcklin, J., 1971. Stratigraphic Lexicon of Iran; Part 1. Central, North and East Iran. Geologic Survey of Iran, Tehran, 338 pp.

Sucharovà, J., Suchara, I., Hola, M., Marikova, S., Reimann, C., Boyd, R., Filzmoser, P. and Englmaier, P., 2012. Top-/bottomsoil ratios and enrichment factors: What do they really show? Applied Geochemistry, 27(1): 138–145. https://doi.org/10.1016/j.apgeochem.2011.09.025

Torab, F.M., 2008. Geochemistry and metallogeny of magnetite-apatite deposits of the Bafq mining district, central Iran. Unpublished Ph.D. Thesis, Clausthal University of Technology, Germany.

Torab, F.M. and Lehmann, B., 2006. Iron oxide-apatite deposits of the Bafq district, Central Iran: an overview from geology to mining. World of Mining- Surface and Underground, 58(6): 355–362. Retrieved June 23, 2025 from https://sciexplore.ir/Documents/Details/816-174-421-583

Torab, F. M. and Lehmann, B., 2007. Magnetite-apatite deposits of the Bafq district, Central Iran: apatite geochemistry and monazite geochronology. Mineralogical Magazine, 71(3): 347–363. http://doi.org/10.1180/minmag.2007.071.3.347

USEPA, 1997. Exposure Factors Handbook; Office of Research and Development, National Center for Environmental Assessment, U.S. Environmental Protection Agency. Washington, D.C, USA. Retrieved June 23, 2025 from https://cfpub.epa.gov/ncea/efp/recordisplay.cfm?deid=236252

USEPA, 2001. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. OSWER 9355, US Environmental Protection Agency, Washington DC, 4–24. Retrieved June 23, 2025 from https://nepis.epa.gov/Exe/ZyNET.exe/91003IJK

USEPA, 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. Office of Solid Waste and Emergency Response: Washington, DC 20460. Retrieved June 23, 2025 from https://nepis.epa.gov/Exe/ZyNET.exe/91003IJK

Wang, F., Guan, Q., Tian, J., Lin, J., Yang, Y., Yang, L. and Pan, N., 2020. Soil enzyme kinetics indicate ecotoxicity of long-term arsenic pollution in the soil at field scale. Ecotoxicology and Environmental Safety, 191: 110215.  https://doi.org/10.1016/j.ecoenv.2020.110215

Wang, X.S. and Qin, Y., 2006. Spatial distribution of metals in urban topsoils of Xuzhou (China): controlling factors and environmental implications. Environmental Geology, 49(6): 905–914. https://doi.org/10.1007/s00254-005-0122-z

Wild, P., Bourgkard, E. and Paris, C., 2009. Lung cancer and exposure to metals: The epidemiological evidence. Cancer Epidemiology: Modifiable Factors, 472: 139–167. https://doi.org/10.1007/978-1-60327-492-0_6

Xu, Z., Ni, S., Tuo, X. and Zhang, C., 2008. Calculation of heavy metals’ toxicity coefficient in the evaluation of potential ecological risk index. Environmental Science & Technology, 2(8): 31. http://doi.org/10.19672/j.cnki.1003-6504.2008.02.030

Yang, X.Y., Ezizi, M., Ismayil, A. and Hayrat, A., 2021. Assessment of Pollution and Health Risks of Heavy Metals in Surface Dust in Changji City, Xinjiang. Environmental Science & Technology, 44(5): 211.  Retrieved June 23, 2025 from https://www.sciengine.com/AJE/doi/10.7524/AJE.1673-5897.20200203001

Ying, L., Shaogang, L. and Xiaoyang., 2016. Assessment of heavy metal pollution and human health risk in urban soils of a coal mining city in East China. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 22(6): 1359-1374.  https://doi.org/10.1080/10807039.2016.1174924

Yuan, G.L., Sun, T.H., Han, P., Li, J. and Lang, X.X., 2014. Source identification and ecological risk assessment of heavy metals in topsoil using environmental geochemical mapping: typical urban renewal area in Beijing, China. Journal of Geochemical Exploration, 136: 40–47. https://doi.org/10.1016/j.gexplo.2013.10.002

Zhang, Y., Li, S., Wang, F., Chen, Z., Chen, J. and Wang, L., 2018. An Innovative Expression Model of Human Health Risk Based on the Quantitative Analysis of Soil Metals Sources Contribution in Different Spatial Scales. Chemosphere, 207: 60–69. https://doi.org/10.1016/j.chemosphere.2018.04.157

Zheng, N., Liu, J.S., Wang, Q.C. and Liang, Z.Z., 2010. Health risk assessment of heavy metal exposure to street dust in the zinc smelting district northeast of China. Science of the Total Environment, 408 (4): 726–33. https://doi.org/10.1016/j.scitotenv.2009.10.075