AbstractExperiments were conducted to determine the influence of the burrowing mayfly,Hexagenia limbata, on the movement of dihexylphthalate (DHP) and hexachlorobenzene (HCB) from the water column into the sediment. Beakers containing sediment and mayflies were introduced into flow‐through aquaria and were sampled at intervals up to 5 d. Sediment was taken from surface and subsurface areas with and without mayflies. The two experiments were run at concentrations of 14CDHP and 14CHCB of 0.066 and 0.062 ng/L, respectively.Subsurface sediment without mayflies was uncontaminated. Toxicant concentration, based on area (ng/cm2), was greater at the surface than on the burrow walls for both compounds. Concentration in the bottom of the burrow was greater than that in the middle (5 cm deep) for DHP but similar to that at the middle for HCB. Total mass of DHP in the burrow wall was about equal to the mass on the surface, indicating that mayflies were capable of doubling the amount of DHP sorbed onto a given surface area of sediment. The adsorption of contaminants from water pulsed through mayfly burrows increased the depth of penetration and mass of contaminants in subsurface sediment
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