Discharge Cause of Marine Disaster
Khaleej Times - By Muawia E. Ibrahim, Abu Dhabi 03/11/2003

ERWDA specialists conduct investigation

Industrial area shoreline. - KT photo by Iftikhar Shaheedi

Low oxygen levels in the water and high nutrients resulting from improper discharges from industries in the Mussafah channel may have caused last week's marine disaster which led to the death of thousands of fish off the shoreline of Abu Dhabi's largest industrial area.

Investigations were performed on the dead fishes that were found floating on the waters and the shoreline stretching for almost 2km from the edge of the channel.

During routine inspections on Tuesday, the Environmental Research and Wildlife Development Agency (ERWDA) inspectors noticed the presence of the dead fish in the channel located to the south of Mussafah industrial area.

A team of specialists rushed to the site to assess the situation. The team conducted observations, field measurements and collected samples over the following two days.

An inspection team from the Environment Section of Abu Dhabi Municipality noticed the incident during a routine inspection of the area. It also collected samples of the dead fish for analysis.

The affected Channel is about 10km long, and is narrower than 0.5 km for most of its length, although there are a number of enclaves reaching about one kilometre in width.

The channel is closed from its eastern side, and links to a wider navigation channel to the west.

According to sources at ERWDA, field measurements conducted by the agency's team of experts showed reduced oxygen levels in the water, with maximum reduction in the middle third of the channel.

"Analyses of seawater samples showed that levels of nutrients (nitrate, nitrite, phosphate and silicate) in the inner parts of the channel were higher than near its mouth. An outlet was seen discharging large quantities of effluents in the innermost part of the affected channel, with some green algae growing around it," the sources said, quoting a report on the investigation.

The report said the source of the water being discharged from this outlet could not be ascertained, but it may derive from the many activities occurring in Mussafah industrial areas and its vicinity.

‘An outlet was seen discharging large quantities of effluents in the innermost part of the affected channel, with some green algae growing around it.’

In addition, several other outlets were seen protruding from the shorelines of the affected channel, although none of them were discharging at the time of the investigation. It is possible that industrial or other mix discharges of sewage from any of these outlets may have contributed to the accident.

On Tuesday, a large number of dead fish were observed either floating in water, with the highest concentration in the middle third of the channel, or stranded on the lower reaches of the channel.

Most of them were showing clear signs of decay, indicating that they died no less than one day earlier.

The number of dead fish on Wednesday was considerably lower, with some showing little signs of decay, suggesting that they died more recently.

On the same day, seawater in the affected channel was found discoloured and covered with foam at locations.

Seawater in most of the channel was showing a dark greenish colour when examined vertically at close range, and bluish colour when looked at an angle from a distance.

This was in contrast with the lightly greenish colour seen outside the affected channel, and that predominates in the area under natural conditions. On Wednesday, but the colour was slightly closer to normal,the report said.

Although ERWDA has been following this investigation since Tuesday, results were not made public pending the outcome of analyses.

"We have decided not to make any speculations, before investigation on the incident is concluded. This was mainly not to create undue alarm or panic, as the affected area started to show signs of going back to normal starting on Wednesday," an ERWDA official said.

"Now since the results of investigation became known, ERWDA will address the issue of such discharges with the concerned parties and to rehabilitate the affected site, and agree on measures that would prevent its recurrence. ERWDA stresses that all concerned parties must obtain permits from the agency before authorizing or making any discharges," the official said.