Published Paper Details:

It was observed that at very low concentrations the toxicant is deadly toxic and affects the BGA. With the increase in the concentration of cadmium chloride the percent survival of the exposed alga decreased and hundred percent death was noticed at 1.88 mg.l-1 of cadmium chloride with in a period of 15 days. The maximum allowable concentration (MAC) recorded for this alga for 15 days exposure was 0.31mg.l-1. The lethal concentration values for 15 days of exposure periods have been outlined below. The LC10 value was 0.48 mg. l-1. The LC50 value was 0.78 mg l-1. LC90 value was 1.22 mg l-1 and LC100 value was 1.88 mg l-1, for this particular alga, Anabaena cylindrica. The control set showed 100% survival. Out of the above concentrations, LC00 or PS100 as safe MAC value of 0.31 mg.l-1 was selected as 'X'; LC50 or PS50 of 0.78 mg.l-1 was selected as 'Y' and LC90 or PS10 value of 1.22 mg.l-1was selected as 'Z' for conducting future experiments. The optical density study and the dry weight analysis indicated that the toxicant cadmium in the form of cadmium chloride is deadly toxic. Cadmium did not show any dichotomous behavior. In recovery studies, no significant recovery was seen at lower concentration and no recovery at all at higher concentration indicated that cadmium caused irreparable damage to the exposed system. Complete bleaching of the algal mass inside the test solution (Z) was observed from 3rd day of exposure period onwards. Gradually tiny blue-green particles started making their appearance in the white turbid mass as observed in the naked eye after 30 days of recovery period. These particles grew in size with time. It was probably due to the appearance of photosynthetic pigments which disappeared due to the heavy metal (Cadmium) stress on the alga. Slowly the entire white mass got converted into a blue-green mass with the increase in recovery period (60 days of recovery).