Strontium Concentration in Soil

Strontium

• Strontium 88 makes up approximately 83 percent of the naturally occurring strontium. The three other natural forms go by the designations strontium 84, 86 and 87. Of the 16 major radioactive isotopes, strontium 90 causes the most concern because of its long half-life. Strontium 90 has a 29-year half-life, but the other radioactive isotopes have a less than 65-day half-life.

Uses

• Strontium 90 comes from nuclear reactor waste. It sometimes also gets into reactor fluid and parts. The radioactive decay of strontium 90 can be turned into electricity for weather stations and space vehicles. Naturally occurring strontium has similarities to calcium and barium. It can be used like calcium and barium, but the high cost makes this use uncommon. Flammable strontium compounds create the reds in fireworks and flares.

Environmental Strontium

• When strontium 90 gets into soil, the concentration depends on rainfall, wind and other factors. The average is 0.1 picocuries per gram. Strontium 90 will move easily through the soil, so it will move down with water. Strontium prefers to combine with soil rather than water. In a sandy, water-filled soil, the level of strontium will be about 15 times higher in the soil than the water. The maximum amount allowed in drinking water, according to the Environmental Protection Agency (EPA), is 36 picocuries per liter.

Risks

• According to the EPA, ingesting strontium 90 with food or water remains the main source of exposure, but has declined since the suspension of nuclear testing. You can inhale strontium 90 through dust from contaminated soil. Everyone has been exposed to small amounts. When ingested, about 80 percent gets eliminated from the body. The remaining 20 to 30 percent gets deposited in bone and bone marrow because of the similarities it has to calcium. Internal exposure increases the risk for bone cancer and leukemia.