Effect of cooling water chlorination on primary productivity of entrained phytoplankton at Kalpakkam,east coast of India

We studied the effect of various concentrations of chlorine, used in the cooling system of Madras Atomic Power Station (MAPS), on the primary productivity of entrained phytoplankton from October 1988 to December 1990. The rates of primary productivity (gross) were lower at the discharge point than in the intake area. The reduction in productivity ranged from 30 to 70% at low-dose chlorination (residual chlorine 0.05–0.20 mg l⁻¹ at the discharge point). During shock-dose chlorination, when residual chlorine at the discharge point ranged from 1.10 to 1.50 mg 1⁻¹ the reduction in productivity was 80–83%. A reduction of 16–17% was recorded without chlorination.