Assessment of metal leachability and toxicity from sediment potentially stored on land

Abstract

The aim of this study was to assess the toxicity and metal leachability from three dredged bottom  sediments potentially stored on land. Washing out was conducted at a sediment dry mass to water mass ratio of 1:10. The method relies on washing out pollutants from the examined sample using water with third degree of purity in static/quasi-dynamic conditions. The investigations comprised three 27-h washing out cycles, including leaching in static conditions (19 h) and shaking (8 h). Bottom sediments are complex matrices; therefore laboratory tests cannot always reflect changes in physicochemical  properties, which can potentially take place after a longer period of time. In spite of this, static-dynamic tests conducted under laboratory conditions provide information which enables a rough estimation of the potential threat posed by the studied sediment to the environment, at a given time. It was demonstrated that the leachability of metals during storage of  polluted (Rybnik, Rzeszów) or unpolluted (Narożniki) bottom sediments does not pose a hazard to the  environment. The Microtox test showed low toxicity of test water extracts. Considering their final destination, the potential and actual environmental hazards which the extracted bottom deposits pose should be assessed by determining the leachability of metals.

Keywords: dredged sediments, metals, leaching, toxicity, Microtox