how is ground water polluted

the groundwater pollution depends on the local geology,groundwater flow patterns,pore scale process and molecular scale process.Contamination might spread rapidly within a high conductivity second lens or it might diffuse at a snail's pace through a low conductivity clay.By ground water pollution we men solutes dissolved in water that can render it unfit for our use or unfit for an ecosystem that the water enters.Most natural water contains some amount of dissolved substances which we think of as contaminants.For a contaminant to be true problem ,it must be present at a concentration that poses some significant risk to the health of the human population or to the ecosystem.the 2 sources of ground water pollution are as follows:-

a)Point source;

b)Non-point source.

Point source:-Tanks used for storing fuels and chemicals leak undetected causing contamination.Example;-U.S. Environmental protection Agency estimated in 1996 about 318000 such releases.

Septic system for subsurface disposal of human waste water are the rule in more rural areas not served by sewers and sewage treatment systems and the waste water flows into the leaching field and contaminates ground water.

Landfill were located on property of lower value and in most cases regions where water move rapidly from the refuse to the ground water or surface water polluting it.

Injection wells,uses of pesticides,herbicides,fertilizers etc. cause pollution.Acid leachate and radioisotopes leachate of sulphide and uranium mines causes pollution.

Road salting to remove ice/snow from the roads in cold European nations also contribute to groundwater pollution.

Organic contaminants:-these includes hydrocabon fuels,solvents and other organic liquids were spilled into the subsurface intentionally.they can migrate great distances as a separate liquid,in the aqueous phase and in the gaseous phase.