Influence of pH, electrical conductivity and ageing on the extractability of benzo[a]pyrene in two contrasting soils

Meng, Fanbo and Yang, Xiaodong and Duan, Luchun and Naidu, Ravi and Nuruzzaman, Md and Semple, Kirk (2019) Influence of pH, electrical conductivity and ageing on the extractability of benzo[a]pyrene in two contrasting soils. Science of the Total Environment, 690. pp. 647-653. ISSN 0048-9697

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Higher soil pH and electrical conductivity (EC) were suspected to result in higher extractability and bioavailability of benzo[a]pyrene (B[a]P) in soils. In this study, we investigated the influence of pH, EC and ageing on the extractability of B[a]P in two contracting soils (varied largely in soil texture, clay mineralogy and organic carbon content) over 4 months. Dilute sodium hydroxide (0.2 mol L−1) and sodium chloride (0.1 mol L−1) solutions were used to adjust soil pH and EC either separately or simultaneously. Extractability of B[a]P in these soils was monitored using a mild solvent extraction using butanol (BuOH, end-over-end shake over 24 h), and an exhaustive mix-solvent extraction using dichloromethane/acetone (DCM/Ace, v:v = 1:1) facilitated by sonication and a subsequent NaOH saponification method following the DCM/Ace extraction. Results showed that increased pH and/or EC significantly increased the B[a]P extractability in the sandy soil (GIA). Variance analysis of contribution of pH and/or EC modification and ageing time on changes in B[a]P extractability indicated that in GIA > 55% and over 25% of the changes in B[a]P extractability was attributed to increased pH&EC and pH only respectively. While ageing resulted in >85% of the change in B[a]P extractability in the clayey soil (BDA), following by increased pH&EC (contribution < 15%). Large amount of non-extractable residue (NER) were formed over the ageing period, up to 95% and 79% in GIA/BDA and its modified soils, respectively. Significant correlations were observed between B[a]P BuOH extractability and the exhaustive sequential extraction using DCM/Ace followed by NaOH saponification for all soils (p < 0.001). With slopes of the correlations close to 1, our results indicated that the simple mild solvent BuOH extraction was equivalent to the complex sequential DCM/Ace and NaOH saponification extraction in these soils.

Item Type:
Journal Article
Journal or Publication Title:
Science of the Total Environment
Additional Information:
This is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Science of the Total Environment, 690, 2019 DOI: 10.1016/j.scitotenv.2019.06.445
Uncontrolled Keywords:
?? b[a]pextractabilitysoilageingphecenvironmental chemistrypollutionenvironmental engineeringwaste management and disposal ??
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Deposited On:
15 Jul 2019 13:05
Last Modified:
21 Jul 2024 00:45