Transport and Reactions in the Bioirrigated Zone

Abstract

Abstract Diagenetic reactions of importance to sedimentary biogeochemical cycling commonly involve soluble reactants, products, or intermediates. Processes controlling solute transport, therefore, determine in large part the occurrence of specific reactions, the absolute and relative rates of reactions, and the net transfer of material between environmental reservoirs over a wide spectrum of spatial and temporal scales. These scales range from localized single crystal growth or dissolution to basinwide patterns of sediment-water nutrient exchange. The activities of benthic organisms influence the transport of solutes in surface sediments in a variety of direct and indirect ways, drastically altering elemental cycling processes, reaction rates, and diagenetic properties from what would occur in their absence. All the complexity of benthic biological community dynamics, individual species behavior, and ecological interactions are thus very much a part of solute transport in surficial deposits. This chapter outlines some of the major known effects of benthos on solute distributions and transport, particularly muds, and examines the ways in which these effects have been conceptualized and quantitatively modeled (see also chapter 9). As will become clear, the study of solute transport and reaction coupling in sediment subject to bioirrigation is a very rich area of research, and much remains to be done.