Environmental alterations
Las preocupaciones ambientales incluyen la alteración del suelo, vegetación y ríos locales durante la preparación del sitio la contaminación atmosférica proveniente de la separación, concentración y procesamiento (polvo fugitivo y emisiones de la chimenea); ruido del transporte, transferencia, trituración y molienda del mineral; contaminación de las aguas superficiales por los derrames de los molinos y plantas de lavado; contaminación de las aguas freáticas debido a las fugas de las pilas de relaves y piscinas de lama; contaminación de los suelos, vegetación y aguas superficiales locales debido a la erosión eólica e hídrica de las pilas de desechos; eliminación de los desechos; impactos visuales; y conflictos en cuanto al uso de la tierra.
A menudo, las plantas de procesamiento de las regiones montañosas tienen dificultades para encontrar las áreas adecuadas para represar los relaves del concentrador, y, por consiguiente, descargan estos finos inertes a los ríos torrentosos aguas abajo, se asientan estos materiales en las curvas del río, canales anchos, planicies de inundación y aguas costeras de poca profundidad. Los finos perjudican a los organismos acuáticos, y pueden causar represamiento e inundaciones en las comunidades que se encuentran aguas abajo.
Impact on water
Mining can have harmful effects on surrounding surface and groundwater. If proper precautions are not taken, abnormally high concentrations of chemicals, such as arsenic, sulfuric acid, and mercury "Mercury (element)"), can spread over a significant area of surface or groundwater. The large amounts of water used for mine drainage, mine cooling, aqueous extraction, and other mining processes increase the potential for these chemicals to contaminate ground and surface water. As mining produces large quantities of wastewater, disposal methods are limited due to the contaminants present in the wastewater. Runoff containing these chemicals can lead to devastation of surrounding vegetation.[26] As mining deposits are prone to leaching their contaminants through seepage water and particle erosion, they represent a future risk to the local environment and a potential threat to downstream water quality.[27].
In well-regulated mines, hydrologists and geologists take careful measurements of the water to take precautions and exclude any type of water contamination that could be caused by mining operations. Minimization of environmental degradation is enforced in mining practices in several countries through laws, by restricting operators to comply with standards for the protection of surface and groundwater from contamination.[28] This is best achieved through the use of non-toxic extraction processes such as bioleaching, biooxidation, and bioreduction of metal ions.[29].
Acid drainage is one of the most relevant environmental problems facing the mining industry.[30] Although it occurs naturally in some environments as part of the rock weathering process, it is aggravated by large-scale ground disturbances, such as those characteristic of mining, usually within rocks that contain a large amount of sulfide minerals. When the extraction process exposes sulfides to water and air, together they react to form sulfuric acid. It can dissolve other harmful metals and metalloids (such as arsenic) from the surrounding rock. Acid drainage can be released anywhere in the mine where sulfides are exposed to air and water, including waste rock piles, tailings, open pits, underground tunnels, and leach pads. Acid mine drainage is especially harmful because it can occur indefinitely, long after mining activity has ended.[31].
The five main technologies used to monitor and control water flow at mine sites are diversion systems, containment ponds, groundwater pumping systems, underground drainage systems, and underground barriers. In the case of acid mine drainage, contaminated water is typically pumped to a treatment facility that neutralizes the contaminants.[32] A 2006 review of environmental impact statements found that water quality predictions made after considering the effects of mitigation greatly underestimated actual impacts on groundwater, seepage, and surface water.[33].
The dissolution and transport of metals and heavy metals by runoff and groundwater is another example of environmental problems with mining, with Tar Creek, an abandoned mining area in Picher (Oklahoma), Oklahoma, suffering from heavy metal contamination: mine water containing dissolved heavy metals, such as lead and cadmium, leached into local groundwater and contaminated it.[34] Long-term storage of tailings and dust can create problems. additional, since the wind can easily blow them away from the site, as happened in Skouriotissa, an abandoned copper mine in Cyprus. Environmental changes such as global warming and increased mining activity can increase heavy metal content in stream sediments.[35].
There are three main types of interventions on rock glaciers: their complete or partial removal, the construction of ballast deposits (low-grade barren rock "Ley (mining)") on the glaciers, and the construction of infrastructure on them.[36] The main effect of the removal of rock glaciers is the irreversible loss of a non-renewable water resource, with the subsequent elimination from the hydrological system of a component that contributes to the flows of river basins. pluvionival or nival, and the modification of the landscape.[37][38] The deposition of ballast on rocky glaciers also produces changes in their dynamics and in the stability of the form, due to the degradation of the permafrost due to geothermal and geochemical effects and the aggradation of permafrost with variable ice contents in the deposited material.[37] The collapse of a rock glacier covered with a ballast deposit would not only cause damage to the nearby, but it can also become a debris flow capable of moving long distances, potentially generating alluvium with debris and tailings downstream.[36][39].
air pollution
Atmospheric particles come from blasting, excavation and earthworks, transportation, material transfer, wind erosion of loose soil during surface mining, or any operation that occurs on the surface of underground mines.[40] During material processing, atmospheric particles will be produced by transportation, reduction (sieving, crushing or pulverizing), vehicular traffic, wind erosion of dry areas of the tailings pond, roads and material piles. Suspended particulate matter from mining operations affects the air quality of both the mine and the surrounding area, revealing a high potential for contamination due to and the subsequent impact on human health.
Open pit coal mining creates more air pollution problems with respect to dust, which contains coal particles, benzene-soluble matter, among others.[41] Coal mining and poor air quality in cities near the mines have been linked.[42].
Impact on the ground
Due to the nature of the activity, a main environmental alteration effect of mining is the impact on the physical, chemical and microbiological properties of the soil. Mining alters landscape aesthetics along with soil components such as soil horizons and structure, soil microbial populations and nutrient cycles, which are crucial for maintaining a healthy ecosystem and therefore results in the destruction of existing vegetation and soil profile (Kundu and Ghose, 1997).
due to the mass removal of earth and the generation of sinkholes.
One type of mass soil removal is the so-called mountaintop removal *(MTR) in coal mining in the eastern United States, which impacts the landscape impact, the destruction of forests and the soils that support them and the deposition of material in the headwaters of the valleys, affecting the water quality of the watersheds and the biodiversity downstream.[43].
A sinkhole at or near a mine site is usually due to failure of a mine roof due to resource extraction, weak overburden, or geological discontinuities. Overburden at the mine site may develop cavities in the subsoil or rock, which may be filled with sand and soil from overlying strata. These cavities in the overburden have the potential to eventually collapse, forming a sinkhole on the surface. Sudden failure of the earth creates a large depression "Depression (geography)") on the surface without warning, which can be seriously dangerous for landscape, life and property purposes.[44] During the surface mining process, land degradation, subsidence and eventual mine fires and alteration of the water table are caused, leading to topographic disorder, severe ecological imbalance and damage to land use patterns in and around mining regions.[45] Likewise, it has been studied that the extraction of minerals such as nickel in open pit mines has decreased soil fertility, which subsequently inhibits the growth of seedlings in the surrounding area.[46] -.
Impact on biodiversity
The destruction or drastic modification of the original site and the release of anthropogenic substances can have a significant impact on the biodiversity of the area.[47] Habitat destruction is the main component of biodiversity losses, but direct poisoning caused by material extracted from mines and indirect poisoning through food and water can also affect animals, vegetation and microorganisms. Habitat modification, such as changing pH and temperature, disrupts surrounding communities. Endemic species are especially sensitive, since they require very specific environmental conditions. The destruction or slight modification of their habitat puts them in danger of extinction. Habitats can be damaged when there is not enough terrestrial product, as well as by non-chemical products, such as large rocks from mines that are discarded into the surrounding landscape without concern for impacts on the natural habitat.[48].
Heavy metal concentrations are known to decrease with distance from the mine,[49] and the effects on biodiversity tend to follow the same pattern. Impacts can vary greatly depending on the mobility and bioavailability of the contaminant: less mobile molecules will remain inert in the environment, while highly mobile molecules will easily move to another compartment or be absorbed by organisms. For example, the speciation of metals in sediments could modify their bioavailability and, therefore, their toxicity for aquatic organisms.[50].
The mining industry can impact aquatic biodiversity in different ways. One form may be direct poisoning;[51][52] a greater risk of this occurs when contaminants are mobile in the sediment[51] or bioavailable in water. Acid mine drainage can modify the pH of the water,[53] making it difficult to differentiate the direct impact on organisms from the impacts caused by pH changes. However, it can be observed and proven that the effects are caused by pH modifications.[52] Pollutants can also affect aquatic organisms through physical effects:[52] Streams with high concentrations of suspended sediments limit light, thus decreasing the biomass "Biomass (ecology)") of algae.[54] The deposition of metal oxides can limit the biomass by coating the algae or its substrate, thus preventing colonization.[52].
Biomagnification plays an important role in contaminated habitats: the impacts of mining on biodiversity, assuming concentration levels are not high enough to directly kill exposed organisms, should be greater for species at the top of the food chain due to this phenomenon.[55].
The adverse effects of mining on biodiversity depend largely on the nature of the pollutant, the level of concentration at which it can be found in the environment, and the nature of the ecosystem itself. Some species are quite resistant to anthropogenic disturbances, while others will completely disappear from the contaminated area. Time alone does not appear to allow habitat to fully recover from contamination.[56] Remediation practices take time, and in most cases will not allow for the recovery of the original diversity present before mining activity took place.[57].