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High acidic pH, low alkalinity may be behind Kolong�s aquamarine colour

By Dibya J Borthakur

RAHA, May 31 - Very acidic pH and low alkalinity values of the river water are some of the possible causes of the Kolong acquiring an aquamarine colour from Hariamukh, Raha to Deobali, Phulaguri area.

According to a report published by the Department of Aquatic Environment Management, Raha College of Fisheries, Assam Agricultural University on Saturday, the pH range of the water samples was found to be between 4.5 and 4.9 while the alkalinity values were in the range of 8 to 11 ppm. It is worth mentioning that the congenial pH range for fishes is 7 to 8.5 while the favorable alkalinity for fishes should be between 75 to 300 ppm. The team of hydrobiologists also detected no algae counts in the water samples.

The scientists further opined that anthropogenic pollution sources may be the cause of this dangerous acidic pH and low alkalinity phenomenon which may have led to this aquamarine colour of the water. The source of this anthropogenic pollution must be detected and controlled to revive the original congenial water environment of the Kolong river, they stated.

The team of scientists collected samples of the river water from three sites based on the information given by the nearby villagers where the river water has acquired an aquamarine hue. The water samples were collected from the bank of the area at Khaigar Gaon, Pachim Khaighar Gaon and Kakati Gaon.

Rajdeep Dutta, Assistant Professor, Department of Aquatic Environment Management of the college when asked on impact on the aquatic animals due to low pH of the river water, said, � The pH of the river water may decrease further during night hours reaching a critical value of pH 2 which is known as �Acid death point� for fishes and aquatic organisms. In such a situation, it may be very fatal for fishes as it will lead to their mass mortality. The situation may further worsen as this is the breeding season of most of the riverine fish species. Prevalence of such acidic pH may also impair the reproductive ability of the fishes which will ultimately affect the riverine fish production in the future.�

It is pertinent to mention here that the team of scientists from College of Fisheries, Raha carried on the examination to reveal the mystery of the unusual event as per the instructions by the Nagaon Deputy Commissioner Jadav Saikia who visited the river on Friday afternoon to review the situation.

The DC also appealed the people living on the banks of the river not to use the water for any purpose till the water acquires its original colour. Meanwhile, officials of the Assam Science Society, Public Health and Engineering Dept, Nagaon also collected water samples from the river for examination.

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