Mark Graham

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The smoking gun  – Willowton Oil

Monday, August 26

APPOINTED by the Willowton Group to evaluate the ecological damage arising from the recent catastrophic spill from its Pietermaritburg plant, renowned river specialist Mark Graham has not minced his words on the impact of the pollution spill and the clean-up task ahead.

Graham said there had been no need to do autopsies on dead fish to determine what chemical had caused the massive fish kill.

“It was not as if it was an unknown chemical source that was causing the issue.  We had a smoking gun and knew what the calibre and type of gunpowder that was used,” quipped Graham

And it has not only been fish that have been affected, said Graham, but all forms of aquatic life in the Baynespruit (close to plant) and the Msunduzi River, probably as far as Inanda dam, more than 70 km from the source of the pollution.

The spill (a combination of 1.6 million litres of oil and caustic soda) did a couple of things, said Graham.  Firstly, it turned the water soapy, interfering with the critical dissolved oxygen absorption across the fish gill membranes. “This prevented the fish from being able to extract what oxygen was in the water. This same problem would also have affected aquatic invertebrates (insects) and other life  in the water.”

We have recorded low enough dissolved oxygen (DO) to confirm this cause and which is also congruent with the characteristic  fish behavior when they were dying.

Like the air we breathe, the survival of aquatic life depends on a sufficient level of oxygen dissolved in water. When it drops below levels necessary for sustaining aquatic life, as has happened as a result of the Willowton Oil spill,  aquatic life gets wiped out. Fish, said Graham, basically choke and suffocate, dying of  asphyxia. Many had attempted to climb out the the water. Others had jumped out several metres up river embankments to escape the caustic pollution.

“It’s much like us sucking in a litre of soapy water into our lungs and then trying to breath!,” said Graham. “The detergent would coat the inside of the lungs, upset some very delicate chemistry at the lung interface with the air and prevent oxygen entering the lung tissues.”

Graham said the large die off of aquatic life had further created a secondary hit, with the decomposition of dead material – fish, plants, insects, other bacteria, algae, etc, causing a “microbial bloom”. This in turn, would have “sucked” up much of the residual oxygen in the water – a second hit to the remaining fish and other aquatic life forms!

Impact across the food web

“We are now assessing these impacts, covering all levels of the aquatic system, from algae through to aquatic invertebrates (insects) and fish. Even though the fish are the most obvious and charismatic life form affected, there has been impact across the food web.   Poor land use such as significant illegal sand mining in the lower reaches of the river are compromising the aquatic ecosystem health and will hamper recovery, as well as ongoing sewage pollution in the upper catchment, mainly out of Pietermaritzburg.

Fortunately there has been dilution through the system,” said Graham, referring to steps that Umgeni Water took in flushing the Msunduzi river with water from Henley dam immediately after receiving news of the disaster.

Summer rains will help

“We are already seeing some life either which has survived the spill, or was washed down in the first flush from Henley Dam, or which has has already begun to reintroduce from unaffected tributaries,” said Graham later last week. “This will continue to improve with time and as the summer rains flush the systems.  We will be undertaking regular monitoring of the full system for at least a year to chart the recovery and if necessary intervene to assist this process,” added Graham.

Duzi Disaster Fund

Graham welcomed the establishment of the Duzi Disaster Fund, a fundraising drive established by the Lower Mpushini Valley Conservancy to assist with the clean-up of the river in around the conservancy which is situated less than 7 km downstream of the Willowton Oil plant.

“All efforts to clean up and focus attention on the system, are to be supported,” said Graham. “However  longer term initiatives to address the broader catchment degradation, pollution sources and impacts and finally restoration and rehabilitation, would ensure a longer term and more sustainable approach to the situation,” added Graham.

He also commended the work of the Duzi – Umgeni Conservation Trust (DUCT) which has “championed tirelessly” for many years for an ecologically healthy and biologically diverse uMngeni-uMsunduzi river system.

“All efforts along the way to achieve this need support from the broader society,” said Graham. “So most usefully we need more sustained interventions which are well resourced and coordinated to achieve lasting solutions. It is encouraging that Willowton, after this spill, now appear keen to support this kind of work,” added Graham referring to the proposed establishment of Baynespruit Conservancy funded by Willowton Oil.