OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

2.3.4.5 Air pollution effects
The coal mining industry is one of the major sources of the greenhouse gas methane emitted into the
atmosphere every year. Mining processes release a variety of gases, metal vapours and dusts, as well as
radioactive particles, into the broader environment through discharge from smelter stacks, washoff or leachate
from unrehabilitated and revegetated mine dump and discard areas, or as constituents of mine dump dust. The
environmental impacts of wind-borne dust, gases and particulates from mining activities are primarily related to
human health and ecosystem damage. However, reports of copper toxicity to cattle and wildlife caused by
emissions from copper mines have also been recorded (CSIR & Wates Meiring and Barnard, 1993; Pettersson
& Ingri, 1993, 2000a, b).
2.3.4.6 Soil erosion and sedimentation
Mine construction results in widespread soil disturbance and is associated with accelerated soil erosion,
particularly in areas receiving high rainfalls. Soil, sediments and any associated contaminants are transported
into streams, rivers and other waterbodies, resulting in the loss or alteration of habitats for aquatic organisms,
as well as changes in water quality. Soil erosion also promotes a variety of terrestrial ecological changes
associated with disturbed areas, including the establishment of alien invasive plant species, altered plant
community species composition and loss of habitat for indigenous fauna and flora.
2.3.4.7 Tailing dams and impoundment leaks, seepage and breaches
Tailings dams, as well as earth-wall water storage dams and berms, contribute to contamination of local and
regional water supplies via seepage through or around the dam walls or via breaches and/or failures of the
dams themselves. In the Vaal area of South Africa, it has been estimated that over 50,000 tonnes of salts seep
out of tailings stockpiles into the Vaal barrage each year, resulting in extensive contamination of water, soil and
riparian vegetation (Booth, 1994).
Under severe circumstances, dam wall failure may result in large-scale soil contamination and loss of viable
land for agricultural and other forms of use, as well as potential loss of human life.
• 2.3.5 Smelting and refining activities
The primary environmental effects associated with smelting and refining processes include the contamination of
soils, watercourses, and even entire food chains caused by leaching and transportation of pollutants from ore
stockpiles and waste sites (Table 2.2).
All processes where ores are heated (to combust, melt or calcine specific minerals present in the ores) produce
contaminated water, noxious gases and fine dust, and emit heavy metal vapours into the atmosphere (Booth,
1994). These substances settle out onto the surrounding landscape where they may have direct impacts on the
area’s fauna and flora, particularly if emissions contain acidic substances such as sulphur dioxide. In addition,
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