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An analytical model for chemical diffusion in layered contaminated sediment systems with bioreactive caps
Author(s) -
Yan Huaxiang,
Wu Jiawei,
Xie Haijian,
Thomas Hywel R.,
Feng Shijin
Publication year - 2019
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/nag.2992
Subject(s) - bioturbation , sediment , contamination , diffusion , flux (metallurgy) , biodegradation , degradation (telecommunications) , boundary layer , benthic zone , environmental chemistry , soil science , layer (electronics) , damköhler numbers , chemistry , environmental science , geotechnical engineering , materials science , mechanics , geology , thermodynamics , composite material , geomorphology , physics , engineering , ecology , telecommunications , oceanography , organic chemistry , biology , combustion
Summary An analytical model for contaminant transport in multilayered capped contaminated sediments including the degradation of organic contaminant is presented. The effect of benthic boundary layer was treated as a Robin‐type boundary condition. The results of the proposed analytical model agree well with experimental data. The biodegradation of contaminant in bioturbation layer shows a significant influence on the flux at the surface of system. The maximum flux for the case with t 1/2,bio = 0.07 year can be 4.5 times less than that of the case without considering the effect of biodegradation. The thickness of bioturbation layer has a significant effect on the performance of the capped contaminated sediment. The maximum flux for the case with l bio = 15 cm can be 17 times larger than that of the case without bioturbation layer. This may be because the effective diffusion coefficient of sand cap can be 28 times lower than D bio . The mass transfer coefficient should be considered for the design of the capping system as the contaminant concentration at the top of system for the case with k bl = 2.5 × 10 −5 cm/s can be 13 times greater than that of the case with k bl = 10 −4 cm/s. The proposed analytical model can be used for verification of complicated numerical methods, evaluation of experimental data, and design of the capping contaminated sediment systems with reactive cap layers.