engleski

Toxicity of oil industry high density brines using miniaturized algal growth bioassay and Lemna test

Aquatic primary producers have been frequently used for toxicity evaluation of many pollutants. Duckweeds and algae have different levels of complexity and could complement each other in phytotoxicity bioassays. The effects of saturated water solutions of CaCl2, CaBr2 (densities 1300 g/dm and 1610 g/dm, respectively) and their 1:1 mixture on the unicellular green alga Chlorella kessleri and on the floating vascular macrophyte Lemna minor were studied. These solutions are commonly used as high density brines for pressure control in oil wells. They were added in nutrient media in amounts appropriate to achieve 0.5%, 1.0%, 1.5% and 2.0% (v/v) dilutions and during the treatment period their effects on growth were estimated. The 0.5%, 1.0% and 1.5% concentrations of all tested solutions inhibited the growth of Chlorella kessleri at the beginning of experiment, but later the stimulation was noticed. CaCl2 and 1:1 mixture in 2.0% concentration inhibited the growth just at the beginning, while CaBr2 inhibited it during the whole experiment. In Lemna test 1.0% concentration of all tested solutions caused the stimulation of growth during the later phase of experiment. Solutions of 1.5% concentration first inhibited the growth, but then stimulated, while 2.0% concentration showed the inhibition during the whole experiment.

Lemna minor; Chlorella kessleri; high density brines; calcium chloride; calcium bromide

nije evidentirano