Radioactive elements in Water

By Laiba Sarwar

Radioactivity in Water (drinking Water)

• Minute traces of radioactivity are normally found in all drinking water whose concentration vary from place to place.

• Many natural and artificial radio nuclides have been found in water, but most of the radioactivity is due to a relatively small number of nuclides and their decay products.

Natural Radio nuclides

• Some of the radio nuclides that are responsible for the natural radioactivity in drinking water come from radioactive elements, and their decay products, and others are produced continuously by cosmic ray bombardment.

• Of all the natural radio nuclides that occur in water and emit low-LET radiation, potassium-40 is likely to be the most significant. This primordial radionuclide occurs as a constant percentage (0.0118%) of total potassium.

Sources of High-Let Radiation

• Radio nuclides that are produced by the decay of uranium-238 and thorium-232 are widely distributed throughout the earth's crust. The majorities of them are alpha-emitters and include isotopes of polonium, radon, and radium.

• The natural alpha-emitters that occur in drinking water appear to be bone seekers. Of these, radium-226 and its daughters and the daughters of radium-228 probably have the greatest potential for producing radiation doses of some consequence to man.

Sources of High-Let Radiation

• The major additional contribution to the alpha-emissions in drinking water is due to the decay of radium-228; although other alpha-emitting natural radionuclides have been found in drinking water, they occur in exceedingly small concentrations.

• The abundance of the radioactive gas radon-222, which is formed by the decay of radium-226, is not highly correlated with the radium concentration in fresh water.

Artificial Radio nuclides

• To some extent, all drinking water obtained from surface sources will reflect contamination from atmospheric testing of nuclear weapons. The sharp decrease in radioactive fallout since that date has been followed by a corresponding decrease in the radioactivity of surface water.

• It is likely that potassium-40 in soil suspensions also account for such water contamination. Because they account for a major part of the potential dose from nuclear fission and activation products, and because of their biological significance, considerable attention has been devoted to strontium-90, cesium-137, iodine-131, tritium, and carbon-14 as potential water contaminants.

Effects of radioactivity on water

Effects of radioactivity on water

• Grays (Gy)

• Everything on Earth is exposed to radiation.

Risks

• Damage to tissues• Cells• DNA and other vital

molecules• Cancer• birth defects• Abnormalities• Death

Effects of radioactivity on fish• The effects on

reproductive success in fish that have been demonstrated include sterility, reduction in counts of primordial germ cells and reduced testicular weight.

• fertility of aquatic invertebrates

• germ cells • mutations in gametes.

Effects on marine organisms • Reproductive stages and growing

tissues are the most sensitive to radioactivity, notably the eggs of marine fish.

• Radioactive isotopes can be bio accumulated, both within primary producers and by uptake through the food chain.

• Bacteria, fungi and some lichens tend to be relatively tolerant to radioactivity.

• Deleterious effects in the growth patterns of plants and animals.

WHAT IS THERMAL HEATING OF WATER:

• A thermodynamic process increase in temperature of water above its normal existing temperature.

• Contains 42 different minerals.

• High in concentrations are sulphate, calcium & chloride

THERMAL POLLUTION IN WATER:

• Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.

• A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers

SOURCES OF THERMAL POLLUTION

• Nuclear power plants• Coal fired power plants• Industrial affluent• Domestic sewage• Hydroelectric power

CONTROL MEASURES FOR THERMAL POLLUTION

• Cooling towers :Use of water from water systems for cooling purposes, with subsequent return to the water way after passage through a condenser, is called cooling process.

• Cooling ponds :Heated effluents on the surface of water in cooling ponds maximize dissipation of heat to the atmosphere and minimize the water area and volume.

• Spray ponds :The water coming out from condensers is allowed to pass into the ponds through sprayers. Heat from the fine droplets gets dissipated to the atmosphere.

• Artificial lakes :Artificial lakes are man made water bodies that offer once-through cooling. The heated effluents can be discharged into the lake at one end and water for cooling purposes may be withdrawn from the other end. The heat is eventually dissipated through evaporation.