An analytical model for chemical diffusion in layered contaminated sediment systems with bioreactive caps. (1st August 2019)

• Record Type: Journal Article
• Authors: Yan, Huaxiang; Wu, Jiawei; Xie, Haijian; Thomas, Hywel R.; Feng, Shijin
• Is Part Of: International journal for numerical and analytical methods in geomechanics. Volume 43:Number 15(2019)
• Page Start: 2471
• Page End: 2490
• Publication Date: 2019-08-01
• Subjects: analytical model -- bioturbation layer -- capped contaminated sediment -- chemical diffusion -- degradation -- mass transfer coefficient; Soil mechanics -- Mathematics -- Periodicals; Rock mechanics -- Mathematics -- Periodicals; 624.1510151
• DOI: 10.1002/nag.2992
• Languages: English
• ISSNs: 0363-9061

Abstract

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.