Heavy metal uptake by plankton and other seston particles

Abstract

The distribution of heavy metals Cd, Cu and Pb between the dissolved phase and the suspended matter has been studied in a stagnant fresh-water lake Zoommeer with the aim of finding a link between heavy metals and seston particles. Phytoplankton and Zooplankton were identified to species level and their density was determined. The average surface area and average volume, respectively, of each plankton species was calculated from the measured dimensions of 20–200 specimens of each species. Heavy metal concentrations in the dissolved phase and the particulate matter were determined by differential pulse anodic stripping voltammetry.

The seston particles were divided into 10 subdivisions and the total surface area and volume, respectively, of each subdivision was taken as an independent variable for the subsequent multiple regression analysis to find the possible correlations with the heavy metal concentrations. The obtained models can explain a very large part (up to 98% for Pb, 99% for Cd and 87% for Cu) of the variation in heavy metal concentration. An adsorption process appears to govern Cd and Pb uptake by Chlorophyceae and Dinophyceae. In addition, both Cd and Pb can penetrate into Chlorophyceae. In the case of Cu, a specific interaction with the Cyanophyceae has been found. In general, the uptake of heavy metals is highly specific for both the respective metal and the organism.