<P> Because of their size, microorganisms are extremely sensitive to environmental modification, such as modified pH, temperature changes or chemicals concentration . For example, the presence of arsenic and antimony in soils led to a diminution in total soil bacteria . Moreover, as in water, a small change in the soil pH can provoke the remobilization of contaminants, in addition to the direct impact on pH - sensitive organisms . </P> <P> Microorganisms have a wide variety of genes among their total population, so there is a greater chance of survival of the species due to the existence of resistance or tolerance genes in some colonies, as long as modifications are not too extreme . Nevertheless, survival in these conditions will imply a big loss of gene diversity, resulting in reduced potential adaptations to subsequent changes . The presence of few developed soil in heavy metal contaminated areas could be a sign of reduced activity by soils microfauna and microflora, indicating a reduced number of individuals or reduced activity . Twenty years after disturbance, even in rehabilitation area, microbial biomass is still greatly reduced compared to undisturbed habitat . Arbuscular mycorrhiza fungi are especially sensitive to the presence of chemicals, and the soil is sometimes so disturbed that they are no longer able to associate with root plants . Some fungi possess however contaminant accumulation capacity, soil cleaning capacity by changing the biodisponibility of contaminants, and can protect plants from damages caused by chemicals . Their presence in contaminated sites could prevent loss of biodiversity due to mine - waste contamination, or allow bioremediation, that is, the removal of undesired chemicals from contaminated soils . On the contrary, some microbes can deteriorate the environment: which mean elevated SO4 in the water can also increase microbial production of hydrogen sulfide, a toxin for many aquatic plants and organisms . </P> <P> Humans are also affected by mining . There are many diseases that can come from the pollutants that are released into the air and water during the mining process . For example, during smelting operations enormous quantities of air pollutants, such as the suspended particulate matter, SO, arsenic particles and cadmium, are emitted . Metals are usually emitted into the air as particulates . </P> <P> There are also many occupational health hazards . Most of the miners suffer from various respiratory and skin diseases . Miners working in different types of mines suffer from asbestosis, silicosis, or black lung disease...Humans are also affected by the occurrence of landslides and floods . </P>

What impact does mining have on the environment