Acetic acid has a wide range of applications in fields as food industry, in chemistry, in chemical industry and in medicine. Due to its numerous applications in several industries, the pollution of the environment with acetic acid is possible, thus the assessment of its ecotoxicity is imperative. The ecotoxicity of acetic acid was assessed using a growth inhibition assay on duckweed (Lemna minor L.) followed by the determination of fresh and dry weight. The growth inhibition assay and the weight and measurements were conducted in accordance with the OECD 221 guideline on duckweed cultivated under standard conditions. Ten concentrations of acetic acid were tested (0.5%, 0.25%, 0.05%, 0.025%, 0.005%, 0.0025%, 0.0005%, 0.00025%, 0.00005% and 0.000025%). For each replicate, 35 fronds of duckweed were maintained under standard conditions for 7 days, when the number of green fronds, fronds with chlorosis and colonies were assessed. The fronds were then weighted after blotting on paper for the fresh weight measurements. For the dry weight measurements, the fronds were maintained at 60˚C until no weight change was recorded. The average specific growth rate and water content were also calculated from the obtained data. Dose-response curves were plotted based on both total number of fronds and percent inhibition of growth rate with the concentrations of acetic acid, thus enabling the calculation of the median effective concentration (EC50) and median inhibition of growth (ErC50). The results showed that the four highest concentration caused a 100% growth inhibition of duckweed. The total number of fronds, green fronds and colonies increased with the decrease in concentration, while the number of fronds with chlorosis decreased. The five highest concentrations inhibited the growth rate similarly to the positive control, while the five lowest concentrations tested had very low inhibitory effect. Only the highest two concentration cause a decrease of percent water content. Regarding the two dose-response curves, the calculated EC50 and ErC50 values were similar, being 38.8 mg/L and 39.4 mg/|L, respectively. All results showed that acetic acid did affect the common duckweed fronds.

ecotoxicity, common duckweed, acetic acid

biology

Presentation: poster