STATISTICAL ASSESSMENT OF HEAVY METAL CONTAMINATION IN INDUSTRIAL SOILS USING POLLUTION INDICES AND MULTIVARIATE ANALYSIS
DOI:
https://doi.org/10.69980/ndxfq798Keywords:
heavy metals, industrial soils, pollution indices, principal component analysis, hierarchical cluster analysisAbstract
The total concentrations of metals in industrial soils may not adequately reflect enrichment, mobility, bioavailability, or multivariate contamination patterns, thereby necessitating an integrated statistical assessment. This study assessed Cd, Cr, Mn, Ni, Pb, and Zn using 100 soil observations obtained from 50 sampling locations at two depths (0–30 and 30–60 cm). The Wilcoxon signed-rank test, bioavailable fractions, contamination factor, geo-accumulation index, Pollution Load Index, degree of contamination, Spearman correlation, principal component analysis, hierarchical cluster analysis, and Hotelling's T2 test were among the descriptive statistics and statistical analyses. Cd showed the highest contamination factor at both depths, with mean relative enrichment of approximately 3.47 and positive geo-accumulation values at all sampling locations. Pb also exhibited notable enrichment, whereas mean PLI values remained below 1; however, 14% of surface and 10% of subsurface sites exceeded this threshold, indicating localized contamination hotspots. Zn and Pb showed the highest relative bioavailable fractions. Contamination indices and several metals were positively associated with cation-exchange capacity and soil organic matter, highlighting the influence of soil physicochemical characteristics on metal accumulation. PCA showed strong contributions of Cr, Ni, Pb, Cd, and CEC to the dominant component, while HCA identified close Cr–Ni and Pb–Zn associations. Hotelling’s T² analysis further demonstrated a significant overall difference in heavy-metal profiles between soil depths. These findings demonstrate that combining pollution indices with multivariate statistical techniques provides a comprehensive framework for characterizing contamination intensity, vertical variability, inter-metal relationships, and site-specific contamination hotspots in industrial soils.
References
1. Adnan, M., Zhao, P., Xiao, B., Ali, M. U., & Xiao, P. (2025). Heavy metal pollution and source analysis of soils around abandoned Pb/Zn smelting sites: Environmental risks and fractionation analysis. Environmental Technology & Innovation, 38, 104084.
2. Ahmed, M., Aslam, A. A., Aftab, F., Sanaullah, M., Hussain, R., Eiman, E., ... & Zargar, S. (2025). Multivariate analysis of potentially toxic metal contents in soil and vegetables: Enrichment, bioconcentration, translocation from soil to vegetables, and assessment of human health toxicity. Food and Chemical Toxicology, 200, 115413.
3. Bashir, Z., Raj, D., & Selvasembian, R. (2025). Source profiling, pollution and health risk assessment of heavy metals in agricultural soils around an industrial cluster using PCA and GIS-assisted PMF. Environmental Monitoring and Assessment, 197(7), 711.
4. Birch, G., Wang, X., & Liu, E. (2024). Human health risk assessment of metal-contaminated soils in Sydney estuary catchment (Australia). Environmental Geochemistry and Health, 46(4), 125.
5. Gan, L., Wang, J., Xie, M., & Yang, B. (2022). Ecological risk and health risk analysis of soil potentially toxic elements from oil production plants in central China. Scientific Reports, 12(1), 17077.
6. Gogoi, N., Sarma, A., Choudhury, M., Samanta, P., Faizan, M., & Sadhak, S. (2024). Soil heavy metal pollution and ecological risk assessment in disturbed and undisturbed soil of Morigaon, Assam. Discover Environment, 2(1), 13.
7. Hendawy, E., Belal, A. A., Rebouh, N. Y., Shokr, M. S., Sheta, A. E. A. S., Saleh, A. M., & Abou-Hadid, A. F. (2025). Health risk assessment of heavy metals in arid soils of the Nile Delta, Egypt using GIS and multivariate statistical analyses. Plos one, 20(11), e0335394.
8. Hou, D., O’Connor, D., Igalavithana, A. D., Alessi, D. S., Luo, J., Tsang, D. C., ... & Ok, Y. S. (2020). Metal contamination and bioremediation of agricultural soils for food safety and sustainability. Nature Reviews Earth & Environment, 1(7), 366-381.
9. Imoni, O., & Jonathan, E. L. (2025). Data-driven assessment of soil heavy metal contamination in Joinkrama, Rivers State, Nigeria using pollution indices and multivariate analytics. Journal of Materials Science Research and Reviews, 8(3), 628-643.
10. Islam, M. S., Hassan, F. U., Toriman, M. E., Ahmad, R., Bashir, M. A., Rehim, A., ... & Halim, S. B. A. (2025). Spatial assessment and ecological risk evaluation of soil heavy metal contamination using multivariate statistical techniques. Catena, 261, 109550.
11. Kang, Z., Wang, S., Qin, J., Wu, R., & Li, H. (2020). Pollution characteristics and ecological risk assessment of heavy metals in paddy fields of Fujian province, China. Scientific Reports, 10(1), 12244.
12. Karimian, S., Shekoohiyan, S., & Moussavi, G. (2021). Health and ecological risk assessment and simulation of heavy metal-contaminated soil of Tehran landfill. RSC advances, 11(14), 8080-8095.
13. Karthikayini, S., Chandrasekaran, A., Manjunatha, & Bennal, A. S. (2025). Ecological and human health risk assessment of heavy metal contamination in soils of major industrial estates of Tamil Nadu, India. International Journal of Environmental Analytical Chemistry, 105(16), 4509-4528.
14. Kong, F., Chen, Y., Huang, L., Yang, Z., & Zhu, K. (2021). Human health risk visualization of potentially toxic elements in farmland soil: A combined method of source and probability. Ecotoxicology and Environmental Safety, 211, 111922.
15. Kumar, S., & Anshumali. (2025). Heavy metal pollution and health risk assessment in upland and riparian soils of the Ganga River basin. Discover Soil, 2(1), 33.
16. Li, G., Chi, H., Hou, Y., Williams, P. N., Liu, Z., & Cai, C. (2024). Accurate bioaccessibility assessment of soil heavy metals by combining their speciation and in vitro model with human gut microbiota. Environmental Sciences Europe, 36(1), 209.
17. Lin, M., Liu, X., Deng, H., & Lin, Z. (2024). Quantitative analysis of heavy metal pollution sources, influencing factors, and delineation of pollution risk areas in industrial soil: A combined application of receptor models and geodetector. ACS ES&T Engineering, 4(3), 562-571.
18. Liu, Z., Mo, L., Liang, J., Shi, H., Yao, J., & Lun, X. (2025). Heavy Metal Pollution and Health-Ecological Risk Assessment in Agricultural Soils: A Case Study from the Yellow River Bend Industrial Parks. Toxics, 13(10), 834.
19. Mensah, A. K., Marschner, B., Antoniadis, V., Stemn, E., Shaheen, S. M., & Rinklebe, J. (2021). Human health risk via soil ingestion of potentially toxic elements and remediation potential of native plants near an abandoned mine spoil in Ghana. Science of the Total Environment, 798, 149272.
20. Mitran, T., Gunnam, J. R. S., Gourigari, S., & Kandrika, S. (2024). Assessment of depth wise distribution, enrichment, contamination, ecological risk and sources of soil heavy metals over an Industrial area in Southern India. Journal of Geochemical Exploration, 257, 107379.
21. Molla, A., Emmanouil, C., Lolas, A., Charvalas, G., & Kyzas, G. Z. (2026). Quantitative Health Risk Evaluation of Soil Contamination by Potentially Toxic Elements near an Industrial Area in Central Greece. Environmental Processes, 13(2), 31.
22. Saraswat, A., Ram, S., Raza, M. B., Islam, S., Sharma, S., Omeka, M. E., ... & Golui, D. (2023). Potentially toxic metals contamination, health risk, and source apportionment in the agricultural soils around industrial areas, Firozabad, Uttar Pradesh, India: a multivariate statistical approach. Environmental Monitoring and Assessment, 195(7), 863.
23. Sharma, L. D., Bhupenchandra, I., Singh, E. J., Dutta, S., Pandey, Y., Chongtham, S. K., ... & Sahoo, M. R. (2026). Multivariate source apportionment and integrated indexical assessment of heavy metal contamination in northeast Indian wetland sediments and soils. Scientific Reports.
24. Shukla, A. K., Pradhan, M., & Tiwari, O. N. (2024). Heavy Metal Contamination of Surface Sediments-Soil Adjoining the Largest Copper Mine Waste Dump in Central India Using Multivariate Pattern Recognition Techniques and Geo-Statistical Mapping. Nature Environment & Pollution Technology, 23(3), 1363.
25. Stefanou, S. (2026). Soil physicochemical properties and heavy metal concentrations in soils of the Industrial Zone of Thessaloniki city, Sindos – Greece (Version 1) [Data set]. Mendeley Data. https://doi.org/10.17632/wxc3wg7dzs.1
26. Tao, L., Ran, Y., Zhang, Z., Pan, Y., Guo, Y., Zhou, F., ... & Jiao, W. (2026). Heavy Metal Pollution, Source Apportionment and Human Health Risk Assessment: A Case Study of Soil in Bohai New Area Industrial Park. Soil and Sediment Contamination: An International Journal, 1-17.
27. Tarighat, H., Baghdadi, M., & Nasrabadi, T. (2025). Integrating native reference values with fractionation and multi-index analysis for heavy metal risk assessment in industrial soils of the South Pars Economic Energy Zone, Iran. Environmental Pollution, 127543.
28. Verma, F., Singh, S., Dhaliwal, S. S., Kumar, V., Kumar, R., Singh, J., & Parkash, C. (2021). Appraisal of pollution of potentially toxic elements in different soils collected around the industrial area. Heliyon, 7(10).
29. Xia, L., Zhang, Q., Zhang, Y., & Jiang, B. (2025). Source-specific ecological and health risks of potentially toxic elements in an agricultural industrialization town, Shandong Province, China. Environmental Monitoring and Assessment, 197(12), 1313.
30. Xiao, X., Zhang, J., Wang, H., Han, X., Ma, J., Ma, Y., & Luan, H. (2020). Distribution and health risk assessment of potentially toxic elements in soils around coal industrial areas: A global meta-analysis. Science of the Total Environment, 713, 135292.
31. Xu, D., Shen, Z., Dou, C., Dou, Z., Li, Y., Gao, Y., & Sun, Q. (2022). Effects of soil properties on heavy metal bioavailability and accumulation in crop grains under different farmland use patterns. Scientific Reports, 12(1), 9211.
32. Zhang, J., Wang, X., Li, J., Luo, J., Wang, X., Ai, S., ... & Liu, Z. (2024). Bioavailability (BA)-based risk assessment of soil heavy metals in provinces of China through the predictive BA-models. Journal of Hazardous Materials, 465, 133327.
