Influence of zinc on lotic plants

Abstract

The toxicity of zinc to Hormidium rivulare Kiitz. in laboratory culture media is decreased by rises in the levels of magnesium, calcium and phosphate, and increased by rises in pH and cadmium. Tiie effects of all these are sufficiently marked that they may be expected to liave considerable importance in the field. In contrast, assays with sodium, chloride and sulphate showed no detectable influence of these ions on zinc toxicity.When applied at higher concentrations, calcium was always more effective than magnesium, but the reverse was sometimes true at lower concentrations. Both magnesium and phosphate were more effective in reducing zinc toxicity with zinc-tolerant populations than with zinc-sensitive ones. Cadmium was highly toxic, either alone or in combination with zinc; however, calcium had a proportionately greater effect in reducing cadmium toxicity than zinc toxicity. Tlie toxic effects of zinc and cadmium were synergistic, and it seems probable that the presence of cadmium at levels of 0.01 mgl"' and above will usually lead to a significant increase in the toxicity of any zinc also present. Cadmium (in the absence of zinc) was 34 times more toxic than zinc to a zinc + cadmium sensitive population, and 15.5 times more toxic to a zinc + cadmium lolerant population. Because of the synergistic response, cadmium had an even greater effect in the presence of zinc.

Influence of phosphorus on copper sensitivity of fluvial periphyton: the role of chemical, physiological and community-related factors

“…Many studies support the hypothesis that metal toxicity is reduced in response to increases in P concentrations (Harding and Whitton 1977; Say and Whitton 1977; Chen 1994). On the other hand, several studies indicate that metals can induce nutrient limitation which can result in reduced algal growth (e.g.…”

Cyanobacteria Diversity in Blooms from the Greater Sudbury Area

“…Metal contaminants (zinc, copper, etc.) and the use of fertilizers and detergents containing phosphorus has been found to cause cumulative effects on cyanobacteria by inhibiting growth; although the presence of calcium and phosphate in the presence of metals has also been found to reduce their toxicity to cyanobacteria [44] [45]. Morphological effects of elevated copper include the production of sub-spherical rather than coccoid Synechococcus PCC 6301 [45] as well as the inhibition of photosynthesis in Nostoc calcicola [46].…”

Patterns of toxicity behavior in different types of microbial culture

“…Both toxicants and nutrients can play major roles in microbial population dynamics is important in natural aquatic ecosystems as well as in laboratory toxicity testing. Several studies have reported that metal toxicity on algae is affected by the phosphate concentration (Say and Whitton, 1977;Shehata and Whitton, 1982;Chen, 1994). Chen (1994) also demonstrated that the average tolerance of algal cells decreases with the concentration of phosphate.…”