Here is a wake-up call for the Forest and Environment Department. A new study has shown that industrial and urban effluent load is fast polluting the estuary waters in the deltaic zone of Mahanadi which feed and sustain the mangrove forests of Bhitarkanika National Park.
Investigation of water quality at six sites revealed higher residue of chloride, phosphate and magnesium as well as total dissolved solids (TDS) which are a direct result of waste being released into the river.
The report, which appeared in American Journal of Marine Science, carried out water analysis for pH, conductivity, TDS, dissolved oxygen (DO), chloride, calcium, magnesium, total hardness to examine the important parameters of pollution at six stations covering river water of Jamboo, mangrove forest water near Kharnasi, prawn farm at Nuagada and Triveni, Mahanadi river where IFFCO and PPL effluent is released.
The chloride content was found in the range of 4389 mg per litre to 12,575 mg per litre at different sites. “According to the limit standardised by State Pollution Control Board, the limit of chloride for drinking purpose is 250 mg/l and can be extended up to 1000 mg/l. The observed chloride contents at all the sites are beyond permissible limits, the report stated. This may be due to contamination caused by waste from terrestrial runoff or of anthropogenic in origin.
Similarly, phosphate content showed a gradual increase from October to December before declining. On an average, the phosphate content ranged from 0.55 mg/l to 2.59 mg/l throughout the study period. The concentration was higher near industrial effluent points. However, nitrate content was below the permissible limits.
The report found significant variation in calcium content during the six-month study period which varied from 125.4 mg/l to 400.8 mg/l.
The Bureau of Indian Standards has set the permissible limit for calcium at 75 mg/l, which the study said can be relaxed up to 200 mg/l. The higher value of calcium registered during the study period may be due to the influx of industrial waste and sewage to the river water.
“In estuarine water, the variation of concentration of calcium is quite significant due to land drainage, high rates of biological uptake, precipitation and dissolution process characteristics of shallow system,” the report mentioned.
Magnesium content in water samples saw the highest count pegged at 474.13 mg/l against the low of 153.16 mg/l. It was way above the permissible range of 30 mg/l to 70 mg/l/. Since estuaries get organic and inorganic inputs exported from agricultural land and urban areas through drainage basins, magnesium content goes up.
The pollutants can cause significant change in the quality of water and pose some deleterious effect to the mangrove ecosystem in the long run, the study said. The study called for immediate attention of the State Government for protecting Bhitarkanika which is home to over 70 species of mangroves, estuarine crocodiles and birds.
The study was conducted by BC Behera, Department of Biotechnology, North Odisha University, Baripada, RR Mishra of MITS School of Biotechnology, Bhubaneswar, JK Patra of National Institute of Technology, Rourklela, SK Dutta, IIS, Bangalore and HN Thatoi, College of Engineering and Technology, Bhubaneswar.