Cosmas Butunyi
25 July 2007
Nairobi — A new wave of concern has been raised over the magnitude of environmental and health impact occasioned by oil spills.
When a loaded Kampala-bound tanker owned by Mr Salah Mukbil overturned on the Kisumu-Busia highway near Ugunja Township recently, there was a massive oil spill into River Nzoia that was only a few metres away.
The 40,000-litre fuel loss was shared between a siphoning crowd and the environment.
There is no way of determining the actual amount of oil deposited into the river out of that oil spill near Ugunja township.
Anthropogenic factors, particularly deforestation in upper catchments, unsustainable fishing practices and pollution from agro-based factories have drastically reduced fish stocks, explains Ms Dorothy Nyingi, a researcher at the National Museums of Kenya.
"Fish species in the river, such as Labeo (known as Ningu in Luo), whose fragile population is reported to have declined significantly in the river are likely to plunge quickly into disappearance due to such spills," she says.
Ms Nyingi reveals that the main danger of oil to aquatic organisms is the smothering effect.
"The oil film prevents proper oxygenation of the water and this stresses fish and other aquatic fauna. Molluscs and other benthic invertebrates that are incapable of locomotion are likely to be the most affected victims of spills," she says.
Oil spills, Ms Nyingi adds, affect aquatic fauna, especially larval stages of insects that float on the water surface during the most sensitive parts of their life cycles.
Such larval stages and plankton are important sources of food for fish and other organisms, and their consumption could lead to accumulation of oil in the food chain, hence long-term toxic effects, she adds.
"Ingestion of oil may lead to impairment of physiological functions such as reproduction, growth, feeding, as well as kidney failure, intestinal destruction and neural disorders," Ms Nyingi says.
Water birds die because their feathers are covered by oil and they ingest poison while trying to clean itself, she adds.
Aquatic organisms react differently to oil spills. Fish react by swimming away.
River Nzoia, she reveals, is an important breeding ground for certain fish species and an oil spill can disrupt the reproductive cycle.
Dr Tom Andebe, the Nyanza Provincial Director of Public Health, says the effect of oil spills on humans largely depends on the distance from the point where it enters the river system to where it gets ingested into the body.
The only effect that oil spills can have on humans is indirect - when they consume aquatic species that have ingested the oil, Dr Andebe adds.
When oil is ingested, directly through water or indirectly through food, it can lead to oil poisoning which can be fatal, says the New Nyanza Provincial General Hospital medical superintendent, Dr Joseph Odondi.
"Soon after the spill, oil droplets can also be inhaled through the nose into the respiratory tract where they infiltrate into the lungs," Dr Odondi adds.
Now, the National Environmental Management Authority (Nema) has put in place measures to ensure quick responses to oil spills to minimise their effects on the environment.
This includes an incident reporting line, which the Nyanza Provincial Director of Environment, Mr Samuel Inganga, says was established for quick response to emergencies.
"When the spills occur, Nema mobilises other organisations to help arrest the situation," he adds.
When there is too much oil spill, Mr Inganga adds, the river may remain dead for a few days and strategies to accelerate degradation of the oil are put in place.
When oil comes into contact with vegetation, as it did at the Ugunja accident, it causes stress on the vegetation which eventually die off since the plants cannot carry out normal functions, says Mr Inganga.
Oil has adverse effects when it lands on soil. It percolates and if it is not put to agricultural use immediately, it is degraded, he adds.
"Bacteria that is naturally present in the soil takes between 7-14 days to breaks down the oil," Mr Inganga adds.
Following the oil disaster at River Nzoia, Ms Nyingi recommends an analysis by a toxicologist to test oil properties in the waters and the land nearby in order to deduce severity of the disaster.
Drinking or contact
"Further effects on humans must be considered. Drinking or contact should be discouraged until such an analysis is carried out. This will help in mitigating the effects of the spill," she advises.
Fish kills, according to Ms Nyingi, have been noted in oil spills within less than a week of such disasters.
Mr Inganga says the amount of damage to the environment by oil is determined by the quantity deposited.
For a large turbulent river like Nzoia, he adds, the oil does not concentrate at one point because of a high dilution factor but there is fast dispersion rate, leading to a reduced effect on the aquatic ecosystem.
"As an organic compound, oil is degraded through natural processes by bacteria as the water flows, breaking it into harmless substances," he says.
Highly dispersed
According to Ms Nyingi, oil spills in rivers are more highly dispersed than other water bodies because of the river movement.
Oil, she adds, forms a thin film on the water and high temperature encourages its spread.
"Certain natural environmental processes such as evaporation of lighter toxic components of oil, oxidation of hydrocarbons into water soluble compounds upon contact with oxygen, biodegradation of oil by bacteria and emulsification when oil mixes with water, reduce the effects of spills," Ms Nyingi argues.
These processes, she says, depend on time and quantity of the spill and may reduce this effect on animals and humans.
River Nzoia is a source of water for domestic use besides being home to aquatic life including fish, frogs, toads, and microorganisms.
Mr Inganga says that as the river flows towards Lake Victoria where it drains, its water mixes with oil.
Lake Victoria is the world's second largest fresh water lake, providing water to residents of Kisumu and other urban centres nearby and is also an important source of fish for local consumption and export.
Fishing, Ms Nyingi observes, is an important factor in the socio-economic status of the population around the Nzoia River and the threat of oil spills should be checked.
Be the first to Write a Comment!
Copyright © 2007 The Nation. All rights reserved. Distributed by AllAfrica Global Media (allAfrica.com). To contact the copyright holder directly for corrections — or for permission to republish or make other authorized use of this material, click here.
AllAfrica aggregates and indexes content from over 125 African news organizations, plus more than 200 other sources, who are responsible for their own reporting and views. Articles and commentaries that identify allAfrica.com as the publisher are produced or commissioned by AllAfrica.
