BIOINFILTRATION - INTRA-SEDIMENTARY PARTICLE TRANSPORT BY BURROW-IRRIGATING ORGANISMS

In this presentation, we describe a new form of intra-sedimentary particle transport, caused by the bioirrigating activities of burrowing organisms. In laboratory mesocosms, particles of kaolinite clay were found to be transported advectively into pore spaces close to the interface between two buried sand layers by the burrow-ventilating activities of the mud shrimp Upogebia pugettensis. The term ‘bioinfiltration’ is used to describe the process. Given the abundance of bioirrigating organisms in shallow marine environments, bioinfiltration may be a widespread phenomenon affecting the properties of large sediment volumes. Clay minerals commonly act as sites of early diagenesis of clay mineral cements, thereby controlling the porosity and permeability of sedimentary rocks. Bioinfiltration needs to be considered, therefore, when assessing the diagenesis of bioturbated sediments. More broadly, the potential for bioinfiltration of other clay-grade materials will be of significance to sediment biogeochemistry and ecology, particularly if these materials are rich in organic matter or other bioavailable particulate nutrients.