By Ivan Kibuka-Kiguli
Anyone that has used the Mbuya-Kireka route via Kinawataka swamp in Kampala has noticed the offensive odour emanating from the swamp, particularly the area where heavy goods vehicles are driven into the swamp for a wash.
This odour is not only a nuisance to all who use the environment around the swamp, but is an indicator of a much larger problem - the presence of hydrogen sulfide gas.
According to Wikipedia, Hydrogen sulfide is the chemical compound with the formula H2S. It is a colourless gas with the characteristic foul odour of rotten eggs; it is heavier than air (meaning it will hang around us rather than rise into the sky), very poisonous, corrosive, flammable and explosive. The implications for inhaling it do not sound pretty.
H2S often results from the bacterial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers.
This process is commonly known as anaerobic digestion because it happens in the absence of oxygen (air). H2S also occurs in volcanic gases, natural gas, and some well waters. The human body produces small amounts of H2S and uses it as a signaling molecule. Dissolved in water, hydrogen sulfide is known as hydrosulfuric acid or sulfhydric acid, a weak acid.
Because swamps hold considerable volumes of stagnant water, they are natural sources of this gas which explains why other swamps may also be afflicted by the odour albeit not as severely as Kinawataka is.
What makes the Kinawataka odour more offending and worrying are the human activities that dog it. Industrial and domestic waste is discharged into the swamp, leading to the death of a variety of flora and fauna. While this is happening, oily discharge from the same industrial and domestic sources as well as the local truck washing activities ensure a fatty/oily film seals off any gaseous exchange between the stagnant water and the air.
We now have both the anaerobic conditions and the raw materials the bacteria require. A feast then commences and finally H2S gas breaks through the surface.
Unaware that the water in the swamp is now acidic and the odorous air we are inhaling is poisonous, we shrug off the nuisance and life continues. When we finally fall ill from this exposure, we fork out some more money to treat the 'mysterious' and stubborn ailments.
When we do not respect nature and compound issues for ourselves by misusing our natural resources, we should not be offended when it pays back in kind. The majority of the community around many swamps may not be aware about the impact they have on these swamps by way of how they take advantage of these resources.
For this reason, government agencies like NEMA and local leaders have their work cut out in not only enforcing anti-pollution measures but in creating positive awareness among the Ugandan population too. It is cheaper and easier to educate Ugandans about the benefits of good environmental management practices than to enforce environmental restrictions/orders.
The writer is an environmental engineering consultant