Effects of water hardness on the toxicity of heavy metals to Daphnia magna

Abstract

The paper presents a comparative study of the toxicity of chromium and molybdenum, carried out in hard aquarium 0,14⁰Clark and soft natural 8,2⁰Clark waters. A decrease in water hardness leads to an increase in the acute toxicity of metals, which is expressed in a decrease in the values of semi-lethal concentrations by 3 times for molybdenum and 25 times for chromium.The results obtained show that the toxicity of metals can differ significantly in waters with different hydrochemical compositions. The data presented in the work can be used in the development of regional MPC standards.