Elutriate Tests Research Articles

Kepone and other selected chlorinated hydrocarbon pesticides and PCBS behavior during hydraulic dredging of the James River near Hopewell, Virginia

Abstract Field and laboratory studies were conducted on the behavior of Kepone and fifteen other chlorinated hydrocarbon pesticides and PCBs during the dredging of the James River, Virginia near Windmill Point. Over a period of six hours, water samples were collected from an area extending three miles up and downstream from the end of the dredge discharge pipe outfall. Laboratory experiments involved mixing sediment and water samples at a 1:4 ratio for 30 minutes and separation of the aqueous phase by cen‐trifugation (elutriate test). Data on field samples showed that the “release”; of chlorinated organic residues, including Kepone, was mainly associated with the colloidal and particulate matter. The elutriated test results indicated a slight tendency for release of chlorinated organic residues in the soluble and colloidal fraction. In samples collected from the contaminated Bailey Creek area, higher concentrations of Kepone were detected in the soluble or colloidal fraction than found from sediments collected in the nearby James River. Data on Kepone in water and sediment suggest that the compound exhibits a behavior different from the other common chlorinated organic residues.

Examination of the Elutriate Test, a Screening Procedure for Dredging Regulatory Criteria

Water quality parameters were considered in a series of tests, including the Standard Elutriate Test designed to appraise the elutriate techniques. Both the conditional stability constant and the complexing capacity of the elutriate were greater than those of background waters. Although the concentration of the Standard Elutriate can be greater than 1.5 times the original concentration for the four heavy metals considered (Zn, Hg, Pb, Cd), it may be still less than the standards for drinking water and fresh water or marine aquatic life. Thus, such releases themselves should not significantly affect the water quality. It appears that improvement of the existing dredging regulatory criteria concerning Hg, Pb and Zn is desirable. On the other hand, our tests indicate that the release of phosphorus can be large and might significantly affect the water quality in actual open water disposal. It is suggested, therefore, that further research be performed to elucidate the behaviour of phosphorus release from dredged spoils, and that the concentrations of phosphorus and other constituents in the elutriates be compared to the standards. Finally, it is suggested that an acceptable test should realistically reflect the occurrence at the disposal site and consequently, should at least incorporate an estimated resulting sediment-water ratio and a mixing process representative of the dump site.