Use of ecotoxicity assessment for determining reusability of treated marine sediment on terrestrial land

Abstract

Contaminated marine sediment can be treated to satisfy the concentration-based chemical criteria, but the treated sediment could still not be appropriate for reuse. This study used ecotoxicity tests to determine the reusability of treated marine sediment on terrestrial land. Changes in the toxicity of sediment contaminated with a mixture of total petroleum hydrocarbons (TPH) and heavy metals after treatment were investigated using both terrestrial (earthworm and wheat) and aquatic organisms (Daphnia magna, Allivibrio fischeri). The contaminant concentrations were reduced to meet the remedial goal of this study. As a result, the toxic effects on the tested organisms were reduced. The toxic effects of the reference sediment sample (RSS) that represents the background sediment toxicity were greater on wheat and earthworms than the treated sediment samples (TSSs). This was attributed to factors such as salinity and sediment texture. By comparing the toxicities of the sediment samples with that of the RSS, it was found that not only the contaminant concentrations, but also the sediment physicochemical properties such as pH, salinity, particle size distribution, and nutrient contents need to be considered from the step when the treatment processes are selected. In conclusion, different aspects of the treated marine sediment quality, apart from the level of contaminants regulated, could be tested using ecotoxicity tests to determine the reusability of the treated marine sediment on land.