Chemicals entering marine waters are incorporated into distinct compartments and these reservoirs are in exchange with one another. The chemo-dynamic storage compartments in marine systems include sediment to the depth of bioturbation (0-50 cm), suspended sediments, dissolved phases (pore, ventilation and overlying water), and tissue residues. The key transport processes are particle flux across the sediment-water interface, vertical mixing within the bioturbation zone, and dissolved contaminant exchange between suspended particles or sediment and surrounding seawater or interstitial water. The key transport variables in entrainment are physical shear, bioturbation, and sediment cohesiveness. Vertical mixing may be mostly a function of the rate of conveyor-type feeding. Dissolved exchange between solid and dissolved phases is controlled by concentration gradients, partitioning relationships, organic matter, surface area, and sometimes redox conditions. Irrigated burrow systems account for most exchange of solutes and deep burial of newly deposited solids.