During a mining project, it is not only the external appearance of the landscape that will change drastically. The different types of mining can cause a broad range of different types of pollution and disruptions. The impact of mining on the ecosystems cannot be underestimated.
Water plays a crucial role in this context. During the extraction process, larges masses of fresh water are required. The supply of this water causes desiccation, water scarcity and sometimes salinisation of the neighbouring lands. During the extraction proces, large quantities of soil and rocks are also moved. The water that flows off carries much of these materials along with it and causes sedimentation in the rivers.
Yet, not only soil and rocks are carried away. The technology employed for the extraction of minerals use extremely poisonous chemical products that often end up in the ground water. The current gold and silver mining techniques use cyanide to split the gold or silver from useless ores. Cyanide is very poisonous, the deadly dose for a human ranges between 3-10mg/kg. For the extraction of copper and nickel, sulphuric acid is used. In case of mismanagement of these processes, accidental leakages or accidents, these chemicals are released into the environment. Cyanide normally degenerates once it comes into contact with oxygen, yet under some circumstances the river can spread it over a distance as far as 60 kilometres.
Moreover, the heavy metals that were originally stored in the ores are now released (piled up ores react after contact with water and oxygen) and can migrate to the surface and ground waters. This process is called acid mine drainage and is difficult to stop once it has been activated. Until today, soils in the United Kingdom contain mercury as a consequence of mining activities by the Romans.
This environmental pollution constitutes a threat for flora and fauna. The biodiversity decreases drastically. The local population face health problems. Polluted soil and a lack of clean water make agriculture impossible. Due to deforestation and large excavations the environment is severely damaged.
After the closure of a mining site, the company often does not feel responsible for cleaning up the mining wastage and rehabilitate the extraction sites. Informal mining, whereby smaller enterprises and local fortune seekers start to extract without consent or regulations, also has an impact on the environment. It is not surprising that for those initiatives, the control on the level of pollution is minimal. As a result the negative impact can become very substantial despite these excavations occur on a much smaller scale.
Original ecosystems are finally lost, together with all the possible services they could render to the community: ecotourism, erosion control, water management of the region (irrigation and drinking water), food production, and creation of a micro-climate...