Findings – Toxicity – SESAMULS® WO
Cell Numbers
The cell numbers were determined by photometric measurement of optical density. The means and standard deviations of the cell numbers of the control and the treatments are presented in the following table:
| Nominal Concentration in mg/L |
Parameter | Cell Number/mL | |||
| 0 h | 24 h | 48 h | 72 h | ||
| 0 | Mean | 2156 | 12756 | 58392 | 215780 |
| 0 | SD | 0 | 1260 | 10076 | 35087 |
| 1.0 | Mean | 2156 | 9343 | 60009 | 78694 |
| 1.0 | SD | 0 | 2713 | 35888 | 27526 |
| 10 | Mean | 2156 | 11139 | 65039 | 74382 |
| 10 | SD | 0 | 3293 | 6587 | 5390 |
| 100 | Mean | *2156 | *301481 | *559841 | *508457 |
| 100 | SD | 0 | 45753 | 10798 | 19945 |
SD = Standard Deviation
*At the test item concentration 100 mg/L the solution was clouded. Therefore photometric measurement was biased and the calculated cell numbers faulty and not usable for evaluation of the results.
Temperature, Light Intensity, pH
In the following table the pH values, the light intensity and the temperature during the test are stated:
| 0 h | 24 h | 48 h | 72 h | ||
| Light intensity [lux] | 5300 | 5300 | 5300 | 5300 | |
| pH | Concentration in mg/L | ||||
| 0 | 8.8 | – | – | 8.0 | |
| 1.0 | 8.8 | – | – | 7.8 | |
| 10 | 8.8 | – | – | 7.7 | |
| 100 | 8.5 | – | – | 7.2 | |
Microscopical Observations
In the following table, the appearance of the alga at the end of the test is stated:
| Nominal Concentration in mg/L | Normal and Healthy Appearance of the Algae |
| 0 | Yes |
| 1.0 | Yes |
| 10 | Yes |
| 100 | No cells |
Growth Rate and Yield
From the cell numbers, the Growth Rate μ and the Yield were calculated. The means and standard deviations at the end of the test are given in the following table:
| Nominal concentration in mg/L | Growth rate [day-1] | Yield [Cell concentration/mL] | |
| 0 | Mean | 1.53 | 213624 |
| SD | 0.06 | 35087 | |
| 1.0 | Mean | 1.19 | 76538 |
| SD | 0.11 | 27526 | |
| 10 | Mean | 1.18 | 72226 |
| SD | 0.02 | 5390 | |
| 100 | Mean | — | — |
| SD | — | — | |
SD = Standard Deviation
*Because of clouded test solution not usable for evaluation of the results.
Inhibition
The following mean inhibition values were calculated for the Growth Rate μ and the Yield.
| Nominal concentration in mg/L | % Inhibition | |
|
Growth Rate μ |
Yield | |
| 0 | 0 | 0 |
| 1.0 | 22.57 | 64.17 |
| 10 | 22.97 | 66.19 |
| 100 | *100 | *100 |
*Because of clouded solutions, the calculated inhibition values for the highest test item concentration were faulty and therefore not usable for evaluation of the results. Because no alga cells could be observed at the end of the test via microscopic observation, inhibition at the highest test item concentration was stated as 100%.
