As I was growing up, “heavy metal” was a kind of pop music which used relied heavily on synthesisers, percussion, syncopation, and the guitar being distorted with the amlifier. When I began to work in the mining industry, the term took on another meaning, more closely related to the kinds of metals that were being dug up alongside the gold, platinum, palladium, uranium, etc. Now that I live in Nairobi, “heavy metal” refers to some of the pollutants in the waters of the Nairobi and Athi Rivers, which ultimately discharge into the Indian Ocean, having passed through thousands of square kilometers of farmland, and been used for irrigation and drinking water. Among these metals are iron, nickel, cadmium, mercury, manganese, zinc, lead and chromium. They are poisonous to humans and animals alike, even in low concentrations, and can result in birth defects, stunted growth, learning retardation, cancers, behavioural problems, etc. They accumulate in plants and animals that people depend on for their sustenance, and can become more concentrated as they pass up the food chain.
But let us not single out the Nairobi and Athi Rivers, because many of Africa’s rivers have high concentrations of metals, particularly if they pass through industrial areas. For example, the Rand Water Board, which is the principal supplier of water to Johannesburg and its surrounds, is aware of the high number of birth defects in children in its catchment area. This is because over a century of gold mining, has contaminated the ground water with the chemicals used to extract the gold. Arsenic and cyanide feature highly among these. This is not only causing problems for human and animal health, but much of the water is highly acidic and is dissolving the foundations of city buildings.
In its consideration of SDG 6 (Clean Water and Sanitation), the United Nation Environment Programme’s Measuring Progress: Towards Achieving the Environmental Dimensions of the SDGs, published in March 2019, defines a safely manged drinking water service as “the provision of drinking water from an improved source that is accessible on premises, available when needed and free from faecal and priority chemical contamination.” The progress report indicates that only 24% of the population of Sub-Saharan Africa has access to safely managed drinking water (compared with 94% in Europe and North America.) The report also estimates that “more than 150 million people worldwide, most of them in Sub-Saharan Africa, still use surface waters as their primary drinking water source, which are often the direct recipients of wastewater flows.” (p.52).
Not only waters that have passed through industrial processes contain harmful substances: These can enter the water from agricultural and domestic areas as well. Heavy metals are only one category of the “priority chemicals” in the UN definition cited above. Others are drugs which enter the water supply through human and animal waste. Often prescribed by doctors or vets, they can be very helpful in treating specific conditions. But in the wrong place they do untold damage. For example, so many antibiotics not properly disposed of, or used incorrectly, that they are causing more harm than good. They are are now awash in our waterways so that microbes are becoming highly resistant to them, and they are no longer effective in many cases for treating the very conditions for which they were designed. Or hormones used to stimulate growth or breeding in farm animals, can now be swimming around in our drinking water. These drugs belong to the category of persistent organic pollutants (POPs), which include the plastics which we see everywhere on the land, and in the waters.
Other “priority chemicals” used in agriculture, have upset the delicate balance of the whole planet. About 110 years ago Haber and Bosch developed a process to produce ammonia, which is used around the world to produce chemical fertilisers, and which was one of the factors of the so-called agricultural revolution. Alongside phosphates, nitrates have been used “enrich” the harvest, but ultimately they degrade the soil, and pollute rivers and the air. When too many of these chemicals are in the water, algae can bloom in such numbers that they ultimately “kill” the water. Decomposed, the algae can make the water smelly and unfit for any use. Most of us have seen water in that condition.
The obvious thing is to prevent our waters from being contaminated by any of these substances in the first place. Industries should be forced to purify their waste water on site. Wetlands, which can absorb many water pollutants should not be destroyed indisciminately. Rivers are not sewers, or channels for disposing of waste materials. Human settlements should treat their liquid and solid waste, and never allow them to spill into waterways or to percolated down to the water table. This requires a lot of dedication and engineering, and our societies must place sufficiently high priority on the protection of our dwindling water supplies, to actually pay the price of water care. We cannot imagine our effluents will simply wash away downstream, because they become somebody else’s problem and hazard. That is not ubuntu.