Comparative toxicity of an effluent from a chlor-alkali industry and HgCl2
Release of waste waters from industries severely affect aquatic flora and fauna. Effluents from industries involved in the production of pesticides, or from industries utilizing toxic substances in their production processes are of particular concern. One such industry, the chlor-alkali industry, utilizes mercury as a cathode in an electrolytic process. The present study reports the toxicity assessment of the effluent from a chlor-alkali factor, Jayshree Chemicals Ltd., Ganjam, Orissa. The reported production capacity of the plant is 50 tons of NaOH per day. The effluent discharged, 50,000 1 per day, contains mercury ranging up to 1.5 mg/l, much more than the permissible limit of 0.01 mg/l set by the Central Board for the Prevention and Control of Water Pollution, India. The effluent enters the Rushikulya River Estuary and finally the Bay of Bengal. This paper was also designed to determine whether the mercury present in the effluent was toxic or whether the toxicity involved some other parameters of the effluent as well.
Seasonal variations in mercury concentrations in the coastal waters of Kalpakkam, southeast coast of India
Studies were carried out in the coastal waters of Kalpakkam to monitor the seasonal variation in mercury (Hg) concentration. The Hg level (dissolved + acid leachable) ranged from 3 to 50 ppb for surface and 1.5 to 47.9 ppb for bottom-water samples, yielding an annual average concentration of 20.42 ±11.44 and 23.11 ± 13.06 ppb for surface and bottom waters respectively. Strong positive correlation of Hg with salinity and its relatively low concentrations during monsoon and post-monsoon showed that concentration of Hg in this coastal water was mainly of marine origin, indicating absence of any other external source of input. Relatively high Hg concentrations were encountered in bottom samples compared to the surface. Madras Atomic Power Station (MAPS) outfall discharge water did not show elevated Hg level compared to ambient surroundings. The present observed values are significantly lower (30 times) than the earlier reported values from this coast.
Diagenesis, metals and pollution in estuaries
Abstract The distribution of metals in estuaries can be modified as a result of chemical reactions that take place within the sediment column. These reactions can drastically alter the partition of metals between solid phases and solution. This allows metals to diffuse through pore solutions which may result in their enrichment at the sediment surface or in the overlying waters.