LATTICE-AUTOMATON MODELLING OF BIOTURBATION: IMPLICATIONS FOR SHORT- LIVED AND EARLY TRANSIENT TRACERS

The activities of infauna have a profound influence on the fabric and composition of sediments. For example, sediment fabric and structure are modified and biogenic hetero-geneities are created that change the acoustic response and geotechnical properties; contaminants at the sediment-water interface can be removed to depth far more rapidly than by burial alone, whereas "capped " pollutants can be transported back to the surface and re-introduced to the environment; the preserved geological/geochemical record can be funda-mentally altered in terms of both timing and intensity of events, clouding our understanding of climate and palaeoceanography; finally, geochemical reactions can be instigated or significantly promoted, such as the dissolution of carbonates or redox reactions. Most models of bioturbation adopt a continuu