Reductions in the exposure of benthos to sediment-associated contaminants through behavioral modification can also occur for infaunal organisms such as oligochaetes. Understanding partitioning between sediment particles and interstitial water is important for understanding contaminant bioavailability. Field monitoring studies have shown that changes in portions of the ecosystem, particularly changes in the benthic community structure, are correlated with increased sediment-associated contaminants within the Great Lakes. Important sediment properties that enhance sorption, thereby reducing bioavailability, include the organic carbon content, particle size distribution, clay type and content, cation exchange capacity, and pH. Hysteresis effects exist in the time relations between adsorption and desorption of contaminants to sediment. Nonpolar organic compounds associate rapidly with sedimentary materials but desorb more slowly. The biological processes and characteristics that influence the transfer of contaminants from sediments include organism behavior, modes and rate of feeding, source of water — interstitial water versus overlying water — for respiration, and organism size.