Durban – Delicate ecosystems affected by a fire that ripped through a cooking oil refinery in Mobeni last month are struggling to recover.
Mangroves in the Bayhead area, spanning about 15ha and home to numerous land and aquatic species, were hard hit by the fire and resultant oil leak.
The fire – which raged for six hours and was possibly caused by an electrical fault – started at 4am at Africa Sun Oil Refineries, which produces cooking oil, beauty and laundry soap and margarine.
Reaching temperatures of 1 300°C, the blaze ruptured one of the pipes, causing the unprocessed oil to leak into the canals nearby and end up in the mangroves.
The company has not disclosed how much oil leaked into the ecosystem, and the site – being investigated by the Department of Labour – has still not been released back to the company.
The Department of Environmental Affairs earlier this month issued a directive to the company to disclose relevant information, as well as the substances’ toxicity.
The directive focused on the protection of the mangroves and sandbanks.
When the Daily News visited the affected area this week, the team found the sandbanks soaked with a thick, viscous oily substance.
The ground, when pressed, pushed up the substance that has been coating boats, decks and even shoes in the dirty oil.
The air smelled of pungent chemicals and stale oil and the banks were littered with soaked debris and a few dead crabs.
Trees still bore the mark of the oil, showing the levels at which it had initially stood. Some trees sported a 30cm high “oil stripe”.
University of KwaZulu-Natal marine scientists and senior lecturers, Gan Moodley and Dr Deborah Robertson-Andersson, said, in a combined comment, that mangroves were “adaptable ecosystems”.
“However, they are highly vulnerable to oil toxicity and can even be damaged by clean-up activities. Over the past 50 years, approximately one-third of the world’s mangrove forests have been lost.”
The destruction of mangroves, they said, was usually related to human population density.
“Major reasons for destruction are urban development, aquaculture, mining and overexploitation for timber, fish, crustaceans and shellfish. Over the next 25 years, unrestricted clear felling, aquaculture, and overexploitation of fisheries will be the greatest threats, with lesser problems being alteration of hydrology, pollution and global warming.”
They explained that mangrove ecosystems were generally considered to be the most vulnerable and sensitive tropical habitat to oil contamination.
“Reported effects include stunted growth, yellowing, leaf deformities, bark fissuring, leaf stunting, reduced leaf numbers, increased mutation rates, limb loss and defoliation.
“Oil contamination from petroleum storage, refining facilities and oil fields often occurs in areas adjacent to mangrove-dominated habitats. Oil that accumulates in these habitats is difficult to physically remove…”
Recovery of mangrove habitats to oil exposure might take as long as 20 years, they said.
The experts explained the toxicants in the oil had the potential to accumulate in organisms (like crustaceans and molluscs) in the lower levels of the food chain, before being transferred along it to organisms in higher levels (namely predators like fish and birds).
Oils with different densities had different impacts on the trees.
“Light, refined oils such as gasoline and jet fuel contain relatively high amounts of the most water soluble and toxic compounds in oils. Plants and animals that are attached to the underwater portion of the prop roots are especially vulnerable.”
They said these light fuels were also absorbed by the tree roots and could cause mortality in between 24 and 48 hours in certain species.
Heavy oils would have long-term persistence, especially with heavy accumulations.
“This long-term persistence may cause leaf loss and possibly death to heavily-oiled trees. Seedlings may also be affected.”
Bongani Mthembu, Geographic Information Systems (GIS) officer at the South Durban Community and Environmental Alliance, said the impact of this kind of disaster would be “totally irreversible”.
“Usually when spills occur, whether they are petrol or oil, they go into the sea through the stormwater drains. The mangroves are usually spared.
“This oil has stuck on the mangroves; now we have no way to clean it.”
Mthembu said that another spill, in 2012, had also had catastrophic consequences for the environment.
Petrol processing company, Fuel Firing System (FFS) Refiners, confirmed at the time that a small oil leak had been found on the FFS side of the embankment leading to the Amanzimyama canal.
“You can see the trees are not as healthy and the soil is completely soaked with oil,” Mthembu said.
Last week, a petrol leak caused by a fire at Sapref Refineries in Prospecton, also believed to be related to an electrical fault, was discovered.
The petrol is thought to have entered stormwater drains in the area, leading into the harbour.
Sapref has also not yet divulged how much petrol was released.
Daily News