Pollutants can penetrate underground water in various ways: when industrial and domestic sewage drains from storage facilities, storage ponds, sedimentation tanks, etc., through the annular space of faulty wells, through absorbing wells, karst funnels, etc.
To natural sources pollution include highly saline (salt and brine) groundwater or sea water that can be introduced into fresh, uncontaminated waters when operating water intake facilities and pumping water from wells.
It is important to emphasize that groundwater pollution is not limited to the area of industrial enterprises, waste storage facilities, etc., but spreads downstream over distances of up to 20-30 km or more from the source of pollution.
This creates a real threat to drinking water supply in these areas.
It should also be borne in mind that groundwater pollution negatively affects the ecological state of surface water, atmosphere, soils, other components of the natural environment. For example, pollutants found in groundwater can be carried out by filtration flow into surface water bodies and pollute them.
As many scientists emphasize, the cycle of pollutants in the surface and groundwater system predetermines the unity of environmental and water protection measures and can not be ruptured.
Otherwise, measures to protect groundwater outside of the connection with measures to protect other components of the natural environment will be ineffective.
The main sources of chemical pollution of groundwater are industrial effluents entering the aquifer from sedimentation tanks, storage tanks, slurry storage facilities, etc. pollution can also occur through the spread of pollutants in areas of solid industrial waste, storage and storage of petroleum products, discharge of waste water into absorbing wells, as a result of pumping industrial wastewaters into deep horizons, etc.
Thermal pollution of groundwater is associated with an increase in their temperature beyond the permissible limits. This type of pollution can be accompanied by a change in the chemical composition of groundwater, the “flowering” of water, the growth of the content of microorganisms.
The main sources of mechanical pollution can serve as turbid surface and storm water. Microbial pollution is more often exposed to groundwater. Foci of pollution are formed in the presence of fields of sewage and filtration, cattle yards, cesspools, through which direct filtration of contaminated water. And if the soils in the aeration zone lose their purifying properties, groundwater contamination begins. Pollution of groundwater can also occur when waste water is discharged into absorbing wells, pits, wells.
Pollution of artesian waters can occur when wastewater is discharged into absorbing wells, as well as when contaminated groundwater flows through corroded pipes and the annular space of abandoned wells that have defects. Pollution of groundwater by chemicals can go through contaminated surface water, through which the supply of underground water.
In industrial plants, sewage ponds use settling ponds, slurry ponds, storage ponds, evaporation ponds, tailings ponds, ash dumps, etc can also be a source of groundwater pollution. Surface-active substances (surfactants) can enter the groundwater. Pollution of surfactants is observed when using soil methods of wastewater treatment containing surfactants when replenishing groundwater reserves from surface water sources containing surfactants.
The source of pollution of groundwater can be atmospheric precipitation, polluting in the territories occupied by industrial waste, salt removal, in the areas of storage of petroleum products, raw materials and finished products of chemical industry enterprises, warehouses of pesticides and fertilizers.