State-of-the-Art Review on Strontium Toxicokinetics, Mechanistic Response, Alterations and Regulations

Abstract

Strontium is mostly present in oil, coal, soil and rocks in the form of isotopes of four types 84 Sr, 86 Sr, 87 Sr and 88 Sr. It resembles the chemical form of calcium and even replaces the position in bones and other places where calcium finds its importance in the human or animal body. Strontium, if exchanged with calcium in greater quantity, can cause serious effects like cancer in bone and its neighbouring tissues and necrotic lesions. However, the effect is negligible when the exchange is lesser. If present in the geo-environment, strontium compounds in both forms stable or radioactive percolates in the groundwater, but a majority of this compound present in soil remains undisturbed for a considerable amount of time. The permissible amount of strontium which can be acceptable in water according to the US Environmental Protection Agency (USEPA) is 4 mg L 1 . Further presence of strontium up to 240 mg kg 1 in soil is considered as less toxic to grownups not suffering from malnutrition. Anthropogenic and natural activities leading to the release of strontium in the atmosphere pose a chance of transportation and deposition by the wet deposition method. The natural treatment of strontium by biodegradation or hydrolysis does not decay atoms of strontium due to its form. This paper deals with the chemical and physical properties and toxico-kinetics of strontium. Moreover, few points pertaining to health of flora and fauna when it is in direct contact with strontium and the safety concerns with relevant regulations are discussed.

Strontium and Cesium Adsorption on Exopolysaccharide-Modified Clay Minerals

“…The adsorption is also influenced by the metal ion speciation, which is highly dependent on pH. Nevertheless, Cs + is the predominant species in all pH ranges and Sr remains as Sr 2+ ions at a pH range of 0–13.5 and a precipitate of strontium hydroxide (SrOH + ) after 13.5 . Therefore, the pH effect on the adsorption process may be not due to Sr and Cs species change in solution.…”

“…Nevertheless, Cs + is the predominant species in all pH ranges 50 and Sr remains as Sr 2+ ions at a pH range of 0−13.5 and a precipitate of strontium hydroxide (SrOH + ) after 13.5. 51 Therefore, the pH effect on the adsorption process may be not due to Sr and Cs species change in solution. The main mechanism of Cs + and Sr 2+ sorption within the studied pH range may form outersphere complexes on planar surfaces because of adsorption and ion exchange.…”

Bacteria-Induced Calcite Precipitation for Engineering and Environmental Applications

“…Sr can be transported and deposited through the wet deposition method in oil, coal, soil, and rocks as a form of isotopes 84 Sr, 86 Sr, 87 Sr, and 88 Sr as a result of anthropogenic and natural activities that release Sr into the atmosphere. Tis form of Sr prevents its atoms from decomposing naturally during biodegradation or hydrolysis [176]. Terefore, an alternative method such as BCP involves cleaning up the radionuclides safely from the environment and soil.…”