Kochi: A month after a massive fish kill was reported in the Periyar, a scientific report has suggested that industrial waste discharge to the river could have resulted in the environmental catastrophe that caused huge financial losses to a large number of inland fish farmers.

The final report prepared by a team of scientists at the Kerala University of Fisheries and Oceanic Studies (KUFOS) states that an interaction between hydrogen sulfide, ammonia and low dissolved oxygen led to a “highly stressful and lethal environment” for fish and other aquatic fauna in the river.

The KUFOS report in effect contradicts the finding of the Kerala State Pollution Control Board (PCB) which has allegedly shielded the industrial units functioning along the river. A preliminary report by the PCB, submitted soon after the May 20 incident, had stated that no trace of industrial effluents was found in the water samples taken immediately after the fish kill.

The PCB’s finding is that when the shutter of the Pathalam regulator-cum-bridge in the river was opened following heavy rains, a large amount of oxygen-poor water flowed into the river from the upstream side of the regulator, resulting in the fish kill. The PCB’s preliminary finding was reinstated in the state assembly by Chief Minister Pinarayi Vijayan and Fisheries Minister Saji Cherian recently. The CM said that based on the reports submitted by the PCB and KUFOS, it was not able to conclude that industrial waste caused the fish kill.

Though the KUFOS study does not hold industrial units responsible for the fish kill, certain findings in the report do suggest so. A source in the varsity said the PCB cannot categorically state that there was no industrial effluents in the water.
The KUFOS report corroborates the PCB’s finding that a low amount of dissolved oxygen caused the catastrophe. However, it does not stop there. According to the varsity’s report, the low oxygen condition caused by the accumulation of excessive organic matter and nutrient inputs enhanced the production of hydrogen sulphide and ammonia, both highly toxic to fish.

The report goes on to say that the situation might have worsened by the discharge of sulphur and sulphates into the water causing hydrogen sulphide production. The report, as if stressing the point it wants to convey, mentions that there are industries known to discharge hydrogen sulphide directly into water bodies.

The report was prepared on the basis of examining samples of water, fish, and sediments collected from areas such as Kothad, Moolampilly and Varappuzha.

The report also said pesticides and other toxicants found in the samples were far beyond permissible limits. The presence of heavy metals such as cadmium, lead, arsenic, chromium, nickel, copper, zinc, cobalt, manganese and uranium were also found in fish samples, though they need not be lethal immediately.
“Apparently, the PCB’s argument is that if industrial waste was being discharged into the river, how could have the fish in caged farms survive? But then, what if industrial waste, stored illegally by some factories, was discharged suddenly into the water when there was heavy rain,” a KUFOS source reasoned.

The source also said that the argument that the sudden outflow of organic waste accumulated in the regulator-cum-bridge alone caused an oxygen dip in the water. “Naturally, the waste would have diluted as the water level rose,” the source said.
The PCB is expected to submit its final report based on the findings in the KUFOS study too.

The Kerala Malsyathozhilali Aikyavedi, a prominent fisherfolk outfit, which has repeatedly blamed the industrial units along the Periyar for pollution of the river has demanded that Chief Minister Pinarayi Vijayan be removed from the portfolio of the environment for reiterating the PCB’s findings in the assembly.