AccScience Publishing / AJWEP / Online First / DOI: 10.36922/AJWEP026200139
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ORIGINAL RESEARCH ARTICLE

Driving factors of chlorinated OPEs pollution in industrial soils: an empirical study based on machine learning and a novel petrochemical source

Chi Zhu1† Lu Cao1† Enze Pei2 Xin Huang3 Shixiang Dai4 Liang Ding1 Bo Wang3 Changsheng Qu1*
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1 Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Industry and Information Technology, Jiangsu Environmental Engineering Technology Co., Ltd., Nanjing, Jiangsu, China
2 Department of Environmental Engineering, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu, China
3 Department of Environmental Science, School of Environmental and Safety Engineering, Liaoning Petrochemical University, Fushun, Liaoning, China
4 State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu, China
†These authors contributed equally to this work.
Received: 11 May 2026 | Revised: 8 June 2026 | Accepted: 10 June 2026 | Published online: 1 July 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

Chlorinated organophosphate esters (Cl-OPEs), a major class of organophosphate ester pollutants, are ubiquitously detected in industrial soils, yet quantitatively apportioning these contaminants remains a critical challenge. Traditional machine learning-based source apportionment approaches are often undermined by the spatial clustering of monitoring data, a phenomenon known as geographical bias. To address this limitation, this study first identified geographical bias through exploratory data diagnostics and subsequently constructed a robust random forest-based machine learning prediction framework that excludes geographical features to eliminate the confounding effect of spatial bias. The optimized model exhibited excellent reliability in predicting soil Cl-OPEs concentrations (test set R2 = 0.90). Model interpretability analysis via feature importance assessment confirmed E-waste processing (site function category_E-waste processing) as the primary driver of Cl-OPEs pollution. To validate the model and explore overlooked sources, we also conducted an empirical case study of the petrochemical industry. Comparative analysis not only confirmed E-waste processing areas as the primary source but also identified the petrochemical industry as a previously underestimated yet significant source of emissions, with its coil Cl-OPEs levels markedly exceeding those of other traditional industrial areas. Overall, this study proposes a novel, geographical-bias-free machine learning source apportionment method and provides new preliminary empirical evidence supporting pollution control of Cl-OPEs.

Graphical abstract
Keywords
Organophosphate esters
Machine learning
Soil pollution
Industrial areas
Funding
This work was financially supported by the National Key Research and Development Program of China (Grant No. 2022YFC3703200).
Conflict of interest
The authors declare they have no competing interests.
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Asian Journal of Water, Environment and Pollution, Electronic ISSN: 1875-8568 Print ISSN: 0972-9860, Published by AccScience Publishing