Toxicity of effluent from a titanium dioxide factory on some marine animals

Abstract

Toxicity of effluent from a titanium dioxide factory containing sulphuric acid residue with soluble iron metallic salts and insoluble material such as silica, etc. on fishes, decapods and molluscs was studied. The effluent caused changes in <i>p</i>H and oxygen depletion of the sea water. Sublethal effects of the precipitate of ferrous salts were also studied. Dilutions of effluent up to 1:150 were LC₁₀₀ for all organisms used while 1:200 dilution was LC₅₀ for fishes at 36 hr and for other organisms at 48 hr. But death of organisms at this concentration was caused by pH changes and O₂ depletion and did not account for the effects of the precipitate. Below this level precipitation started soon after mixing with sea water causing death of organisms by choking their gills and siphons. Dilutions ≤1:1000 were 96 hr LC_o.