A Case Study of Deep DNAPL Contamination in Marine Soft Clays

Aquifers in China’s southeast coastal areas are protected by the overlying marine soft clays formed in Holocene transgression. However, a fundamental understanding of the characteristics of DNAPL (dense nonaqueous phase liquid) contamination in marine soft clays is limited. The study was conducted o...

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Main Authors: Yanbin Gao, Wenqi Ji, Tao Li
Format: Article
Language:English
Published: Wiley 2023-01-01
Series:Geofluids
Online Access:http://dx.doi.org/10.1155/2023/5059543
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author Yanbin Gao
Wenqi Ji
Tao Li
author_facet Yanbin Gao
Wenqi Ji
Tao Li
author_sort Yanbin Gao
collection DOAJ
description Aquifers in China’s southeast coastal areas are protected by the overlying marine soft clays formed in Holocene transgression. However, a fundamental understanding of the characteristics of DNAPL (dense nonaqueous phase liquid) contamination in marine soft clays is limited. The study was conducted on the site of a former pharmaceutical factory in Shanghai, where serious 1,1,2-trichloroethane (DNAPL) contamination was detected up to the depth of 22.0 m below the existing grade. Partitioning calculation method was used to identify the presence of pure phase, and the results showed that pure 1,1,2-trichloroethane was accumulated at the interface of the upper soft silty clay and lower soft clay. The vertical transport was believed to be the pure DNAPL displacing pore water following the principle of two-phase flow, rather than the convection and diffusion of aqueous phase. The contamination (NAPL-soil interaction) impacted the soil properties slightly, and this effect could not account for the deep contamination. Soil structure analysis showed that these clays contained a proportion of large interaggregate pores, providing pathways for the transport of pure DNAPL. Considering their flocculated structure, the marine soft clays are not capable to perform as a barrier to prevent the downward migration of pure DNAPL.
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spelling doaj-art-e937586f1dec4ae08fa6e1ba3c88b8712025-08-20T02:21:53ZengWileyGeofluids1468-81232023-01-01202310.1155/2023/5059543A Case Study of Deep DNAPL Contamination in Marine Soft ClaysYanbin Gao0Wenqi Ji1Tao Li2Department of Geotechnical EngineeringHatch Ltd.SGIDI Engineering Consulting (Group) Co.Aquifers in China’s southeast coastal areas are protected by the overlying marine soft clays formed in Holocene transgression. However, a fundamental understanding of the characteristics of DNAPL (dense nonaqueous phase liquid) contamination in marine soft clays is limited. The study was conducted on the site of a former pharmaceutical factory in Shanghai, where serious 1,1,2-trichloroethane (DNAPL) contamination was detected up to the depth of 22.0 m below the existing grade. Partitioning calculation method was used to identify the presence of pure phase, and the results showed that pure 1,1,2-trichloroethane was accumulated at the interface of the upper soft silty clay and lower soft clay. The vertical transport was believed to be the pure DNAPL displacing pore water following the principle of two-phase flow, rather than the convection and diffusion of aqueous phase. The contamination (NAPL-soil interaction) impacted the soil properties slightly, and this effect could not account for the deep contamination. Soil structure analysis showed that these clays contained a proportion of large interaggregate pores, providing pathways for the transport of pure DNAPL. Considering their flocculated structure, the marine soft clays are not capable to perform as a barrier to prevent the downward migration of pure DNAPL.http://dx.doi.org/10.1155/2023/5059543
spellingShingle Yanbin Gao
Wenqi Ji
Tao Li
A Case Study of Deep DNAPL Contamination in Marine Soft Clays
Geofluids
title A Case Study of Deep DNAPL Contamination in Marine Soft Clays
title_full A Case Study of Deep DNAPL Contamination in Marine Soft Clays
title_fullStr A Case Study of Deep DNAPL Contamination in Marine Soft Clays
title_full_unstemmed A Case Study of Deep DNAPL Contamination in Marine Soft Clays
title_short A Case Study of Deep DNAPL Contamination in Marine Soft Clays
title_sort case study of deep dnapl contamination in marine soft clays
url http://dx.doi.org/10.1155/2023/5059543
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