The sediment-water flux of HOCs due to "diffusion" or is there a well-mixed layer? If there is, does it matter?

摘要: In most present modeling of the sediment-water flux hydrophobic organic chemicals (HOCs), due to sediment erosion/deposition is described explicitly by means a transport model, while remaining components (molecular diffusion, bioturbation, and groundwater flow) are lumped together modeled as "diffusive" flux. This diffusive usually mass transfer approximation with implicit assumption well-mixed contaminant layer thickness h in sediments. On basis recent experiments theoretical modeling, justification for this quantification discussed here. particular, HOCs large partition coefficients, it argued that often may not exist, and, when does, slow form; his difficult define even harder quantify; that, far long-term predictions (up 100 years) concerned, exact value probably does matter. What matter magnitudes time dependencies each interactions between erosion/deposition.