Influence of thermal power station effluents on hydrobiology of seawater

Abstract

The hydrobiological parameters of the waters in the vicinity of ash slurry and cooling water outfall from Ennore Thermal Power Station located on the shore of Bay of Bengal, Madras were determined. In the outfall site, an increase in mean temperature (35 °C), salinity (3.5%), nitrite − N (25 μg L−1), ammonia − N (185 μg L−1), phosphate − P (1 mg L−1), silicate − SiO2 (1.65 mg L−1), chlorophyll a (21.1 mg m−3), respiration (76% of gross production), suspended solids (3.84 g L−1), BOD (3.65 mg O2) and decrease in pH (8.1), dissolved oxygen (DO) (5.5 mg L−1), nitrate − N (15 jig L−1), gross production (16.6 Mg C m−3 hr−1) were recorded. Phaeopigment and respiration were inversely related with chlorophyll a and net productivity, respectively. Microbial biomass varied spatially, but was generally low (114.5 jig L−1), at the outfall site. The hydrobiological characteristics of water with high turbidity indicate that the ash slurry and coolant water play a crucial role in a localized area resulting in environmental disturbance. The effect was profoundly influenced by an initial dilution, dispersion, wave mixing and current direction. The ecological relationships between these parameters and their implications in coastal pollution are discussed.