HUMAN WASTES AND RUBBISH

Human health problems in southern Africa stem mainly from inadequate sanitation. Human waste is a major cause of water pollution in the region.

Human wastes contain bacteria, parasites and diseases, and nitrates. Nitrates are thought to cause a type of blood poisoning which sometimes kills young children. Pollution of groundwater (underground water drawn from boreholes) with nitrates is a dilemma wherever pit privies and latrines are located near boreholes.

Human wastes also cause environmental problems. When human wastes and sewage end up in rivers, nutrients such as phosphorus fertilize the water and stimulate growth of algae and other water plants. The oxygen in the water is used up when there are too many dead rotting plants in the water. Fish need oxygen, so when the oxygen is used up the fish die.

Rubbish dumps

Rubbish dumps pollute groundwater and in some cases surface water (rivers and dams) . Municipal dumps and landfills are among the most serious sources of water pollution in southern Africa. Pollutants in the rubbish dissolve in rainwater. Then polluted rainwater drains off the dump into underground water and surface water supplies.

This is a special concern in this water-scarce region. Toxic wastes such as chemicals and pesticides are often disposed of in municipal dumps which drain into our water supplies.

Most rubbish dumps in the region are not properly managed. Anybody can dump anything in the dumps. Anybody can scavenge. While scavenging provides for reuse and recycling of waste materials, and reduces the total amount of waste that must be disposed of, people are in danger of being poisoned by chemicals, agricultural wastes and other hazardous wastes dumped together with the useful items.

Part of the problem is the siting of rubbish dumps. The sites are not usually chosen with a view to protecting water supplies. In one case a rubbish dump was purposely located in flooded sand pits. The idea was to use the rubbish as landfill. Officials now recognize that the scheme has a high potential to pollute the area's drinking water.

Another problem is that dangerous wastes are not always dumped in the 'official' waste dump. Industries seeking to keep their costs down dump wastes in vacant lots and beside roadways. This has been reported in most countries in the region. Local councils often lack transport and equipment to collect and treat the abandoned waste.

INDUSTRIAL WATER POLLUTION

In southern Africa most factories and industries discharge their effluents (waste water) directly into rivers or the ocean. Effluents contain poisons harmful to plants and fish in the water, and to people and animals using that water.

Wastes from pulp and paper mills are among the worst industrial pollutants. Pulp mills use strong chemicals to soften wood pulp and bleach it white. These chemicals end up in the environment where they poison fish and other forms of life.

Textile factories, battery factories, fertilizer plants, tanneries and other industries cause water problems as well. In Botswana a factories inspector reported the pollution of the Peleng River with liquid industrial waste. Fish died out, and boreholes which provided drinking water for Peleng Village, had to be closed.

INDUSTRIAL AIR POLLUTION

Certain industries produce a lot of air pollution which affects the health of people and the environment nearby. Major air polluters include chemical manufacture (sulphuric and nitric acids), iron and steel plants, cement manufacture, and thermal electric power stations.

Since it has the most industry, South Africa has the most serious air pollution problem in the region. Annual emissions of air pollutants such as sulphur dioxide, nitrous oxides, carbon dioxide, carbon monoxide and hydrocarbons exceed 125 million tonnes over South Africa's industrialized areas.

The area most notorious for air pollution is the Eastern Transvaal Highveld, where most of South Africa's electricity is produced. Each year the area's coal-fired power plants emit more than 57,5 tonnes of sulphur dioxide per square kilometre, a higher concentration of sulphur dioxide than anywhere else in the world.

When acidic gases such as sulphur dioxide combine with rain the result is 'acid' rain. Acid rain damages plants and soil. It even eats away at vehicles and steel roofing.

POLLUTION FROM AGRICULTURE

Agrochemicals include pesticides and herbicides (chemicals to kill insect pests and weeds), acaricides (cattle dips), and fertilizers. Agrochemicals are major pollutants of both the farm and the wider environment.

Pesticides

Pesticides can be extremely dangerous to the users. It was estimated in 1990 that 11 million people in Africa are poisoned by pesticides every year. A small percentage of the poisonings are fatal, though exact numbers are not known.
Pesticides used on irrigated crops such as sugar cane can pollute the river water and poison fish downstream. Most countries in the region with irrigation schemes have reported accidental fish kills from pesticides.

Improper?storage of pesticides and pesticide containers results in pollution. For example in 1988 the Daily News reported that at Kibaha in Tanzania there were 50 tonnes of mixed up pesticides stored without any covering against the rain. Much of the pesticide mix was carried away by rainwater and washed towards wells and rivers. Plants nearby were severely affected.

Fertilizers

Fertilizers cause pollution when they are washed into streams and rivers. Adding fertilizers to water is similar to adding human wastes and sewage. Algae and water plants grow faster and use up the oxygen.

Erosion

Even ordinary soil can be a pollutant. In Swaziland the government has identified eroded sediment as the country's major river pollutant. Too much sediment changes the river's environment. It smothers plant life and chokes fish.

Cattle

If cattle manure is allowed to pile up it can seep into the ground and pollute the groundwater. This is a big problem in Botswana, where cattle are often concentrated near boreholes.

Agricultural industry

Agriculture and agriculture-related industries use (and pollute) a great deal of water. For example in Lesotho 60 percent of the water used in the country is used by the livestock industry. The water is returned to the environment polluted by organic wastes.

POLLUTION FROM VEHICLES

Fumes from cars, trucks and buses normally contain pollutants such as nitric oxides and hydrocarbons. Sunlight turns these pollutants into 'photochemical' smog. Motor vehicle exhaust can be a locally significant source of air pollution and smog, especially when vehicles are not properly tuned.

Most petrol sold in southern Africa contains lead. Tiny lead particles are ejected from vehicles with the exhaust. Heavier particles fall to the ground where they pollute soil up to fifty metres away from the road. A Zimbabwean study recommended that food should not be grown close to busy roads, because lead is extremely poisonous.

HOUSEHOLD ENERGY

Smoke from household fires probably causes more health problems in the region than industrial air pollution. Smoke from coal and wood fires contains many poisonous chemicals, and can be a locally significant source of air pollution.

SEASONAL BURNING

Burning of grass and forest fires in southern Africa causes a lot of air pollution high above the earth. The pollutants include the gases ozone, methane and carbon monoxide. These gases build up in the atmosphere for months and even years, and are detectable from space by satellite.

POLLUTION FROM MINING

Mining and mining industries pollute surface waters and groundwater, the air and the land. Mining affects the environment in several ways. The mineral being extracted may be dangerous (such as radioactive rock or asbestos fibres). Fine dust, gases and smoke produced by mining and processing of minerals pollute the air. The overburden (surface soil and rock) dug up during mining is piled up in dumps which take up good land and pollute soil and water. Surface waters draining the dumps of waste rock carry pollutants to agricultural land and drinking water supplies. Waste water released from mineral processing pollutes groundwater and surface water.

Mining in SADC countries (southern Africa, excluding South Africa) contributes an estimated one million tonnes annually of sulphates to the atmosphere. Air pollution affects the health of nearby residents. In Zambia 20 percent of health problems in children under 15 are respiratory, largely because of air pollution from mining.

Small-scale gold miners also cause environmental problems. Digging up the riverbanks causes siltation of rivers and ruins fish habitat. Miners use toxic substances such as mercury and cyanide to extract the gold. Some of the mercury and cyanide escapes into the water and air where it poisons the environment and people nearby.

POLLUTION OF THE OCEAN

The main sources of pollutants in the ocean are oil spills and waste disposal from coastal towns.

Oil spills introduce cancer-causing poisons into the water. The oil smothers marine plants and fish, reducing their resistance to infections and disease.

An estimated 33250 metric tonnes of oil end up in the Indian Ocean every year along southern Africa's east coast. Ships release the oil during cleaning operations and normal emissions (on any one day there are more than 600 ships cruising East African waters). The oil reaches the beach in the form of tar flakes and tar balls.

Along southern Africa's west coast, it was estimated several years ago that about 5,000 tonnes of oil and grease are released into the sea every year. Fishing near Luanda, Cabinda and Pointe Noire (Congo) has been affected by spills from oil drilling platforms.

Large oil spills are infrequent but only South Africa has the technology to handle oil spill emergencies. There have been two major oil spills off the coast of Tanzania, in 1981 and 1986, and two off the coast of Mozambique, in 1982 and 1992. Two ships collided off the coast of South Africa in 1977 and spilt 25,000 tonnes of oil. Between 1965 and 1981 there were 128 oil tanker accidents off the southern coast.

"Though spectacular events such as oil spills attract much attention, about three-quarters of the pollution in the sea emanates from land-based sources," wrote Jacklyn Cock and Eddie Koch in their 1991 book Going green : people, politics and the environment in South Africa. Southern African countries discharge more than 800 million litres of effluent into the ocean every day through more than sixty pipelines at various points round the coast.

Urban planners assume that wastes will wash away once they reach the ocean, but because of ocean currents the pollutants often tend to collect rather than disperse.