Groundwater is a hidden resource. At one time, its purity and availability were taken for granted. Now contamination and availability are serious issues.
Why should I be aware of it?
Groundwater is important because it is the main source of drinking water and irrigation. In certain areas such as the US, the quantity of groundwater is 20 to 30 times greater than the amount in all the lakes, streams, and rivers in the country.
Apart from being a significant source of water supply, the quality of ground water directly impacts our health and the environment. Most groundwater sources are less prone to drought and, therefore, can be more reliable than surface water supplies. Groundwater wells, however, are susceptible to plugging, bacterial contamination, and other water supply and quality degradation problems.
All about ground water
When rain falls to the ground, some sinks into the ground. This water is stored in the spaces between rock particles and slowly moves underground, through the layers of soil, sand and rocks that allow the water to permeate through. These particles comprising gravel, sand, sandstone, or fractured rock, like limestoneare are called aquifers. The depth at which the acquifier gets saturated is called the water table.
Ground water and surface water
Groundwater and surface water are fundamentally and "feed" each other. One can also contaminate the other. Groundwater naturally arrives at the surface in the form of spring water.
Groundwater and health
Ground water gets polluted when toxic chemicals from hazardous waste in landfills leach into the soil. Among various organic and inorganic water pollutants, pesticides are very dangerous and harmful because of their association with tissue degradation and carcinogenic nature.
The typical range of concentrations of chemicals in contaminated groundwater is measured in in micrograms per liter (µg/L), which is the same as parts per billion (ppb). Though there is no direct evidence linking groundwater contamination by pesticides to any chronic health effects, experts warn that at high concentrations, impact on consumers of this water would be chronic in nature — those that may occur as a result of many years of exposure to the chemical. Examples of chronic health effects include cancer, birth defects, organ damage, nervous system disorders, and immune system damage.
Groundwater and environment
The major sources of pesticide pollution are industries, agriculture, forestry and domestic activities. The pesticides from domestic, industrial and agricultural effluents enter the ground/surface water. The persistence of organochlorine pesticides in water has a special significance as they are picked up by unicellular organisms like plankton, fish, etc. and in the process pesticide residues enter the food chain. The pesticides applied to the plants and crops enter the grain, fruits, etc. and are finally consumed by humans and other organisms.
- Groundwater may not be confined only to the earth. The formation of some of the landforms observed on Mars may have been influenced by groundwater. There is also evidence that liquid water may also exist in the subsurface of Jupiter's moon Europa.
- Scientists estimate groundwater accounts for more than 95% of all fresh water available for use.
- Approximately 50% of Americans obtain all or part of their drinking water from groundwater.
- Nearly 95% of rural residents rely on groundwater for their drinking supply.
- About half of irrigated cropland uses groundwater.
- Approximately one third of industrial water needs are fulfilled by using groundwater.
- About 40% of river flow in the US (on average) depends on groundwater.
- Ground Water
- The Ground Water Supply and Its Use
- Groundwater contamination and health hazards by some of the most commonly used pesticides
- Which Pollutants Are Toxic?
- A Guide for Watershed Partnerships