KARACHI: Heavily polluted with toxic metals and chemical compounds, the Lyari River is degrading marine life, poisoning the food chain and negatively impacting the lives of hundreds of thousands of people residing along the channel, says a study recently published in an international journal.

Titled A quantitative appraisal of Lyari River effluent and published in the UK-based Desalination and Water Treatment journal this year, the study was carried out by Prof Moazzam Ali Khan and Dr Aamir Alamgir at the Institute of Environmental Studies, Karachi University.

Under the study, a number of parameters were examined that included the level of the river’s biochemical oxygen demand, chemical oxygen demand, total suspended solids, cyanide, lead, nickel, cadmium, oil and grease, phenol and phosphate.

Lyari River’s biodiversity has been wiped out, says study

“All [were] found to be higher as compared to the National Environmental Quality Standards,” said Dr Alamgir, adding that it’s the first detailed study of the river.

Sharing his observations during the study that took him to various parts of the city, Dr Alamgir said most people were not aware of how and to what extent the toxic waste-water channel was affecting their lives.

“We spotted many points where water supply lines were either completely drowned in the sewage flowing through the channel or leaking, an evidence of mixing of sewage with drinking water lines. We also found pieces of burnt wood and empty cans along the river channel, suggesting that oil and grease was also taken out from the waste water on a regular basis at night by heating up sewage at high temperature, which is likely sold for use in consumer items,” he explained.

He also raised concern over the poor living conditions of people who resided along the river. “Apart from the health risk posed by filthy conditions, the population is also exposed to extremely harmful fumes emanating from the toxic river, which makes them vulnerable to diseases like cancer,” he said.

The local biodiversity of the river, which had clean water till the 1950s, has completely been eliminated over the decades by toxic waste and now only pollution is found along the river, which also serves as a dump for the city’s solid waste.

“A number of drains like the Gujjar nullah and Orangi nullah also merge into the 50km-long Lyari River as it passes through the areas of Sohrab Goth, Abbas Town, Gulshan-i-Iqbal, Liaquatabad, Teen Hatti, Shershah, Keamari Town and Mauripur,” Dr Alamgir observed.

Untreated domestic and industrial waste from North Karachi, F.B. Area and Shershah was also dumped into it.

“Today, more than 200MGD of untreated domestic and industrial waste from this channel goes into the sea directly, which also contributes to degrading the marine ecosystem.

Study’s findings

Under the study, 16 samples of waste water were collected from eight sites before and after the monsoon period.

The findings showed that the most polluted spot was the Mauripur Road bridge, the site where the channel forms an estuary and merges into the sea. It had the highest concentration of lead, nickel, cadmium, copper, arsenic, phenol, oil and grease. It also had the highest value of chemical oxygen demand, indicating continuous accumulation of toxic chemicals in the river.

The highest concentration of cyanide — a toxic metal widely used in electroplating, metal refining, organic chemical production and many other processes — was found at the Lasbela bridge, where the channel receives untreated waste from many cottage industries in the Shershah industrial area.

The highest concentration of phosphate was found from samples picked up along the Sir Shah Mohammad Sulaiman Road in Gulshan-i-Iqbal.

“The presence of phosphate, the main factor contributing to eutrophication in water bodies, is mainly attributed to the use of detergents. During the present study, heavy algal blooms were observed at Lyari River outfall that represents eutrophic condition due to ample input of phosphates and nitrates from untreated effluent,” the study says.

The same spot, along with Teen Hatti bridge, also had the maximum biological oxygen demand value, indicating high organic pollution that could be due to the indiscriminate dumping of municipal waste, it says.

Published in Dawn, May 21st, 2017