Estimating the Effect of pH, Moisture and Heavy Metals Interaction on Worm’s Bioaccumulation Using a Linear Model

Abstract

In the process of vermicomposting, the earthworms Eisenia fetida have been exposed to various metals with different concentrations to study the effects on worms' bioaccumulation. The study was carried within 14 days of exposure. Five different chemical compounds in various concentrations were added as mixture solutions to the experimental containers. Metals concentrations were measured in earthworms by atomic absorption. Ordinary least square technique was used to show metal bioaccumulation in the samples. The model determines the interaction of metals greatly. Moisture in soil has negative effect but pH has great positive effect on the rate of bioaccumulation. In the experiments, worm bioaccumulation is significant for Zinc, Nickel and for most toxic metals, Cadmium and Chromium too. Results lead to a linear dependence of the bioaccumulation on the amount of heavy metals regard to interaction of them, the rate of body burden of the worms which was affected by pH and moisture content.