Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications

The pervassive release of tire and road wear particles (TRWPs) introduces the tire additive 6PPD and its biologically active derivative, 6PPD-quinone (6PPD-Q), into the environment, with soil serving as the primary sink. However, at present their fate in soil is largely unknown. This study considere...

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Main Authors: Dahang Shen, Qingyang Shi, Jingjing Zhang, Nathan D. Sy, Rebecca Yates, Wei Wang, Jay Gan
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Environment International
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Online Access:http://www.sciencedirect.com/science/article/pii/S0160412025002831
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author Dahang Shen
Qingyang Shi
Jingjing Zhang
Nathan D. Sy
Rebecca Yates
Wei Wang
Jay Gan
author_facet Dahang Shen
Qingyang Shi
Jingjing Zhang
Nathan D. Sy
Rebecca Yates
Wei Wang
Jay Gan
author_sort Dahang Shen
collection DOAJ
description The pervassive release of tire and road wear particles (TRWPs) introduces the tire additive 6PPD and its biologically active derivative, 6PPD-quinone (6PPD-Q), into the environment, with soil serving as the primary sink. However, at present their fate in soil is largely unknown. This study considered the transformation kinetics and products (TPs) of 6PPD and 6PPD-Q under different soil conditions. In anaerobic soils, 6PPD persisted substantially longer (average half-life 51.4 d) than in aerobic soils (0.7–1.5 d), indicating that submerged soil or sediment compartments may serve as a more important secondary source. The degradation of 6PPD-Q in soils was mediated by microorganisms, with half-lives (13.5–14.2 d) longer than those of 6PPD under aerobic conditions. Distinct transformation pathways were observed for 6PPD and 6PPD-Q in soil under aerobic and anaerobic conditions, with 10 and 7 TPs identified, respectively. Two of the identified TPs, 1,3-dimethylbutylamine and N-phenyl-p-benzoquinone imine, are known to pose potential human exposure risks. The primary transformation reactions for 6PPD involved C-N cleavage, dehydrogenation, hydroxylation, and amination, while those for 6PPD-Q included dephenylation, hydroxylation, methylation, and amination. The study findings provide critical data for a better understanding of the environmental fate and risks of 6PPD and 6PPD-Q in terrestrial environments and offer valuable insights for pollution control strategies and policy development regarding these and other tire additives.
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spelling doaj-art-eab9db10027e464980231fb918dafafd2025-08-20T03:07:51ZengElsevierEnvironment International0160-41202025-06-0120010953210.1016/j.envint.2025.109532Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implicationsDahang Shen0Qingyang Shi1Jingjing Zhang2Nathan D. Sy3Rebecca Yates4Wei Wang5Jay Gan6Department of Environmental Sciences, University of California, Riverside, CA 92521, USA; Institute of Nuclear Agricultural Sciences, Key Laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, ChinaDepartment of Environmental Sciences, University of California, Riverside, CA 92521, USADepartment of Environmental Sciences, University of California, Riverside, CA 92521, USADepartment of Environmental Sciences, University of California, Riverside, CA 92521, USADepartment of Environmental Sciences, University of California, Riverside, CA 92521, USAInstitute of Nuclear Agricultural Sciences, Key Laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, ChinaDepartment of Environmental Sciences, University of California, Riverside, CA 92521, USA; Corresponding author at: Department of Environmental Sciences, University of California, Riverside, CA 92521, United States.The pervassive release of tire and road wear particles (TRWPs) introduces the tire additive 6PPD and its biologically active derivative, 6PPD-quinone (6PPD-Q), into the environment, with soil serving as the primary sink. However, at present their fate in soil is largely unknown. This study considered the transformation kinetics and products (TPs) of 6PPD and 6PPD-Q under different soil conditions. In anaerobic soils, 6PPD persisted substantially longer (average half-life 51.4 d) than in aerobic soils (0.7–1.5 d), indicating that submerged soil or sediment compartments may serve as a more important secondary source. The degradation of 6PPD-Q in soils was mediated by microorganisms, with half-lives (13.5–14.2 d) longer than those of 6PPD under aerobic conditions. Distinct transformation pathways were observed for 6PPD and 6PPD-Q in soil under aerobic and anaerobic conditions, with 10 and 7 TPs identified, respectively. Two of the identified TPs, 1,3-dimethylbutylamine and N-phenyl-p-benzoquinone imine, are known to pose potential human exposure risks. The primary transformation reactions for 6PPD involved C-N cleavage, dehydrogenation, hydroxylation, and amination, while those for 6PPD-Q included dephenylation, hydroxylation, methylation, and amination. The study findings provide critical data for a better understanding of the environmental fate and risks of 6PPD and 6PPD-Q in terrestrial environments and offer valuable insights for pollution control strategies and policy development regarding these and other tire additives.http://www.sciencedirect.com/science/article/pii/S01604120250028316PPD6PPD-quinoneTire wear particlesTire and road wear particlesTire additivesEmerging contaminants
spellingShingle Dahang Shen
Qingyang Shi
Jingjing Zhang
Nathan D. Sy
Rebecca Yates
Wei Wang
Jay Gan
Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
Environment International
6PPD
6PPD-quinone
Tire wear particles
Tire and road wear particles
Tire additives
Emerging contaminants
title Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
title_full Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
title_fullStr Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
title_full_unstemmed Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
title_short Transformations of 6PPD and 6PPD-quinone in soil under redox-driven conditions: Kinetics, product identification, and environmental implications
title_sort transformations of 6ppd and 6ppd quinone in soil under redox driven conditions kinetics product identification and environmental implications
topic 6PPD
6PPD-quinone
Tire wear particles
Tire and road wear particles
Tire additives
Emerging contaminants
url http://www.sciencedirect.com/science/article/pii/S0160412025002831
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