Incipient erosion of biostabilized sediments examined using particle-fieldoptical holography

Laser holography allows images of three-dimensional space at ultra-high res olution to be recorded onto photographic plates. Recorded scenes can be "re played" with a second laser beam into free space and optically "interrogate d" using either a microscope or a camera by sequentially focusing on increa sing distances from the hologram in the field of view (optical sectioning). From these sections, information on the relative locations and orientation in space of suspended particles as well as the morphology of particles can be obtained. This paper examines the utility of "in-line" laser holography to discriminate the size and the morphology of sand particles eroded under turbulent shear flow during benthic sediment transport. The influence of a commercially available adhesive polymer (xanthan gum, derived from the bac terium Xanthomonas campestris) on sediment stability and resuspended partic le morphology is described. The major implications for carbon and sediment cycling within estuaries are highlighted.