Occurrence and Chemistry of Zinc in Freshwaters – its Toxicity and Bioaccumulation with Respect to Algae: A Review Part 2: Toxicity and Bioaccumulation with Respect to Algae

Abstract

Summary: Zinc has definitely been established to be required for the growth of both higher plants and algae, but it can act either in a stimulatory mode or in an inhibitory one, depending on its level of availability. A variety of environmental fpctors are known to modify the toxicity of zinc in water on algae. It has been observed that algae differ in their tolerance to zinc.It is well known that algae can accumulate zinc or other metals from water, producing an internal concentration greater than in their surroundings. The modes of accumulation and concentration factors are given. Toxicity of zinc on Algae Zinc as a micronutrient for plantsZinc has definitely been established t o be required for the growth of both higher green plants and algae. The earliest study regarding the essentiality of zinc for plants was the one of RAULIN for Aspergillus niger. However, it was not until 1926 that SOMMER and LIPMAN presented convincing evidence for the necessity of zinc as a plant nutrient. Since then there have been numerous confirmations (EYSTER).Zinc has been shown to be an almost universal constituent of living matter and it is now considered essential to the growth and normal development of most microorganisms, plants and animals (RICE, 1961).The discovery of zinc in many highly purified enzymes (VALLEE) has revealed the diversity of its function in protein and carbohydrate metabolism. The isolation and purification of a n enzyme, carbonic anhydrase (4.2.1.1) containing 0.33 O, ' o zinc as part of its molecule, by KEILIN and MANN offered the first concrete explanation of a mode of action of this element. Zinc was demonstrated t o be essential t o the mechanism of action of this enzyme, which catalyzes the dehydration of carbonic acid and participates in the elimination and incorporation of carbon dioxide.WARBURG and LUTTGENS (1944, 1946) presented some evidence which caused them t o speculate that zinc was a heavy metal intimately concerned with Hill reaction activity. They reported that the quantity of o-phenanthroline required to cause 100 O/ " inhibition was almost exactly equal to the amount required t o completely chelate the zinc in the chloroplast fragments. The inhibitory action was corrected by the addition of zinc ions. 7.

Inorganic Contaminants of Surface Water

“…A comprehensive review of factors influencing the uptake of zinc by aquatic plants was prepared by Vymazal (1986).…”