Contribution for the study of zinc impact on a biological model "Lemna minor L"

Abstract

Certain extensive used water treatment processes use duckweeds. Used water discharges are increasingly subject to different types of pollutions, particularly, heavy metals. In this work, we carry out an evaluation of a macrophyte species' tolerance, the duckweed L. minor, to a heavy metal, zinc, through evaluating some indicative parameters for toxicity, such as the number of fronds, fresh weight and growth rate. Our results show that for a first time in a period of 21 days, the plant tolerates all the concentrations of the used zinc in our experiment from 0.003 to 0.018 g/l. Beyond that, it seems that L. minor reaches a threshold of reversible toxicity, demonstrated by the significant reduction in the fresh weight, fronds' multiplication and growth rate, without exceeding 43% for the highest dose.