TY - JOUR

T1 - Enhanced Recovery of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils Using Exhaustive Methanolic and Nonmethanolic Alkaline Treatments

AU - Umeh, Anthony C

AU - Duan, Luchun

AU - Naidu, Ravi

AU - Semple, Kirk T.

N1 - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright ©2018 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.analchem.8b04440

PY - 2018/11/6

Y1 - 2018/11/6

N2 - The fate, impacts, and significance of polycyclic aromatic hydrocarbon (PAH) nonextractable residues (NERs) in soils remain largely unexplored in risk-based contaminated land management. In this study, seven different methanolic and nonmethanolic alkaline treatments, and the conventional methanolic saponification, were used to extract benzo[ a]pyrene (B[ a]P) NERs that had been aged for 180 d from four contrasting soils. Up to 16% and 55% of the amount of B[ a]P spiked (50 mg/kg) into soils was nonextractable after 2 d and 180 of aging, respectively, indicating rapid and progressive B[ a]P sequestration in soils over time. The recovery of B[ a]P from soils after 180 d of aging was increased by up to 48% by the seven different alkaline extractions, although the extraction efficiencies of the different alkaline treatments did not differ significantly ( p > 0.05). Approximately 40% of B[ a]P NERs in the sandy-clay-loam organic matter-rich soil was recovered by the exhaustive alkaline extractions after 180 d of aging, compared to only 10% using conventional methanolic saponification. However, the amounts of B[ a]P NERs recovered depend on soil properties and the amounts of NERs in soils. A significant correlation ( R2 = 0.69, p < 0.001) was also observed between the amounts of B[ a]P recovered by each of the seven alkaline extractions in the contrasting soils and corresponding NERs at 180 d of aging, indicating a potential association warranting further investigations. Extraction techniques that estimate the amounts of PAH NERs recoverable in soil can help give a better understanding of the fate of NERs in soil.

AB - The fate, impacts, and significance of polycyclic aromatic hydrocarbon (PAH) nonextractable residues (NERs) in soils remain largely unexplored in risk-based contaminated land management. In this study, seven different methanolic and nonmethanolic alkaline treatments, and the conventional methanolic saponification, were used to extract benzo[ a]pyrene (B[ a]P) NERs that had been aged for 180 d from four contrasting soils. Up to 16% and 55% of the amount of B[ a]P spiked (50 mg/kg) into soils was nonextractable after 2 d and 180 of aging, respectively, indicating rapid and progressive B[ a]P sequestration in soils over time. The recovery of B[ a]P from soils after 180 d of aging was increased by up to 48% by the seven different alkaline extractions, although the extraction efficiencies of the different alkaline treatments did not differ significantly ( p > 0.05). Approximately 40% of B[ a]P NERs in the sandy-clay-loam organic matter-rich soil was recovered by the exhaustive alkaline extractions after 180 d of aging, compared to only 10% using conventional methanolic saponification. However, the amounts of B[ a]P NERs recovered depend on soil properties and the amounts of NERs in soils. A significant correlation ( R2 = 0.69, p < 0.001) was also observed between the amounts of B[ a]P recovered by each of the seven alkaline extractions in the contrasting soils and corresponding NERs at 180 d of aging, indicating a potential association warranting further investigations. Extraction techniques that estimate the amounts of PAH NERs recoverable in soil can help give a better understanding of the fate of NERs in soil.

U2 - 10.1021/acs.analchem.8b04440

DO - 10.1021/acs.analchem.8b04440

M3 - Journal article

C2 - 30269489

VL - 90

SP - 13104

EP - 13111

JO - Analytical Chemistry

JF - Analytical Chemistry

SN - 0003-2700

IS - 21

ER -