Impact of Effluent of a Chlor-Alkali Industry on the Photosynthetic Efficiency of Crop Field Inhabiting Cyanobacteria

Abstract

The Chlor-alkali industry located at Ganjam, Odisha, India caused aquatic and terrestrial mercury contamination by its effluent and solid waste discharges discharged from the industry containing metallic mercury. The Rushikulya river water and the surrounding area were contaminated, which affected the flora and fauna of the area ultimately affecting live flora and fauna of Bay of Bengal. Toxicity study revealed the acute toxic nature of the effluent. At sub-lethal concentration of the effluent, either no impact or little increment in growth values (dry weight) was noted in case the tested alga available in the contaminated sites. At higher concentrations of the effluent, inhibition of growth was noted in the effluent exposed alga. The pigment contents like chlorophyll, phaeophytin, carotene and c-phycocyanin content significantly decreased as compared to the control algal pigments. It was observed that at sub-lethal concentration of the effluent, growth enhancement was noted but with the increase in effluent concentration growth declined. The pigments initially increased at sub-lethal concentrations and with the increase in effluent concentration the pigments significantly decreased indicating toxic stress. Analysis indicated that with the increase in exposure period the residual accumulation of mercury increased significantly showing a positive correlation (r=0.924; P