Determination of the environmental impact of consolidation induced convective transport through capped sediment

Reactive Transport Modeling of Subaqueous Sediment Caps and Implications for the Long-Term Fate of Arsenic, Mercury, and Methylmercury

“…The minimum thickness will need to be greater than the depth of the habitat layer in order to create a zone of separation between ecological receptors and mercury accumulation (Simpson et al 2002 ). For the range of conditions examined in our study, the maximum thickness is expected to be <1 m, which is consistent with field studies (Moo-Young et al 2001 ). The effectiveness of a sand cap for limiting mercury exposure to biota will depend on a number of site-specific physical, hydrologic, and biogeochemical factors that can be examined with reactive transport modeling as illustrated here.…”

“…Although relatively simple and optimum in low-energy environmental conditions (e.g., lakes, estuaries, low-velocity river reaches), the effectiveness of capping can be compromised when there are diffusive and/or advective fluxes of chemical contaminants from underlying groundwater (Liu et al 2001 ). Depending on the magnitude of these fluxes, successful mitigation may require (1) addition of mineral and organic substrates for adsorption (Moo-Young et al 2001 ; Ying and Axe 2005 ; Viana et al 2008 ), (2) favorable geochemical conditions that promote precipitation (or co-precipitation) of metals as crystalline and/or amorphous compounds (Sengor et al 2007 ), and/or (3) addition of reactive chemical amendments to facilitate sequestration by adsorption or dissolution/precipitation (Jacobs and Forstner 1999 ; Yang et al 2007 ; Kumpiene et al 2008 ).…”