Near-shore marine environments are complex ecosystems where much of the global benthic flux of metals and nutrients take place between the seawater and sediment (Meile et al, 2003). Bioirrigation is the increase of solute transport resulting from introduction of oxygenated water from the surface into the more reduced environment deep within the burrow. Fe and Mn hydr-(oxides) accumulate on burrow margins in response to the oxygen flux into suboxic porewaters and has been shown to trap trace metals (Harding and Risk, 1986; Tessier and Campbell, 1988; Tessier et al., 1979, 1982). The...