VietNamNet Bridge – Ten years ago, a scientist rang the alarm bell over the pollution of the Thi Vai River, while suggesting measures to rescue the river.

Associate Prof Dr Doan Canh

In 1997, Canh’s scientific research on investigating and suggesting solutions to deal with the pollution of the Thi Vai River caused by nearby industrial works was published and then applauded by local authorities and scientists. However, the research work then fell into oblivion until it was discovered to still be a topical issue.

Canh said that though the Thi Vai River does not play a role in providing water, but that it is located in three provinces and runs through three cities (Dong Nai, Ba Ria-Vung Tau and HCM City) proves to be very important in terms of ecology and environment. There is the mangrove forest ecosystem, the diversified Can Gio biosphere reserves, which can be seen as the natural lung of the localities.

However, as Canh said, the ecosystem of the river has been degraded. On some stretches of the river, the DO index is nearly at zero, and even plankton cannot live in the water. The lung of the localities has become a threat to local residents.

Canh said that he rang the alarm bell over the pollution of the river many years ago, when the signs of the pollution were not as clear as nowadays: shrimps and fishes died and plankton could not live in the river. At that time, Canh could find only one sign: a series of cashew gardens blossomed, but did not bear fruits after a lot of factories and export processing zones appeared.

“However, our warning was ignored,” Canh said.

He added that if local authorities, industries and branches had paid appropriate attention to the cleaning of the river, the Thi Vai would not have fallen into such a tragic plight.

Programming the waste release, the solution for Thi Vai

According to the Centre for Environment Observation and Information, DO index measured in August 2008 was 2mg/litre in the heavily-polluted area, 15 km from Long Tho (Nhon Trach district in Dong Nai province) to Phu My port in Ba Ria-Vung Tau province. The zinc content was 0.039-0.053mg/litre, or 3.9-5.3 times higher than the allowed level.

In fact, the figures could be seen in the research by Mr Canh. He said that if the pollution continues a few more years, the whole river will suffer from heavy pollution which cannot be improved.

Canh’s suggestions, which he made in 1997, still prove to be feasible in the current conditions. According to Canh, the most important thing is the programming of waste release.

It is necessary to minimise and control the waste sources, install waste conducting pipes at the right positions, and use ecological techniques to allow the river to get the ability back of cleaning itself.

In general, the river can clean itself. However, as there is too much industrial waste, the river cannot breathe, and cannot save itself.

Canh said that the waste conducting pipes should be installed in positions which are not depression areas or areas with slow water discharge. The water discharge will help thrust the waste to other areas, and the waste will disappear gradually in the natural transformation, or will not cause danger to people.

Canh said that people, enterprises, scientists and the state should join together to clean the river, stressing that if unanimity cannot be reached among these subjects, environmental protection will not be successful.

Vinh Giang