310
Trace Elements in Abiotic and Biotic Environments
Ratio of exchangeable species of Sr to Ca in soils may be a good predictor of Sr
contents of some plants (Takeda et al. 2005). The interactions between Sr and P are
observed, which are variable, depending on several other factors.
The mushroom Common Chanterelles (Cantharellus cibarius) grown in
mountains  of Poland contain slightly higher amounts of Sr, mean 1.1  mg/kg
(range 0.51–2.6 mg/kg), than those grown in the Baltic Sea coast, mean 0.6 mg/kg
(range 0.14–1.7 mg/kg), (Falandysz et al. 2012). This may indicate higher aerial Sr
deposits in mountains than in low-level regions.
45.6 ISOTOPES
There are several isotopic species of Sr in the geological formations. Their natural
concentrations are 84 Sr—0.56%, 86 Sr—9.87%, 87 Sr—7.04%, and 88 Sr—82.53%. 90 Sr
is also present in the environment as a product of fission reactions, with a relatively
short half-life time of about 30 years.
The ratio of 87 Sr to 86 Sr is typical for any geological formations, and therefore is used
for age determination of rocks, as well as for tracing of industrial aerosol contamination
(Geagea et al. vide Kabata-Pendias 2011). The products of several nuclear processes
are 89 Sr and 90 Sr, and the second radionuclide is considered to be the most biologically
hazardous in the environment. During the period 1945–1980, Sr radionuclides were
released mainly from aboveground detonations of nuclear weapons. After the Chernobyl
accident in 1980, the emission of 90 Sr becomes to be of serious environmental problems.
Elevated concentrations of this isotope in soils of various regions of Russia and Europe
have been reported, and the highest amounts were in soils of Belarus. Its most elevated
contents, up to 340 Bq/kg, were in alluvial soils and organic-rich soils.
Biogeochemical behavior of 90 Sr is similar to stable Sr. The migration velocity of
this isotope is calculated as 0.7–1.5 cm/yr; however, its great part is still located in
the upper 10 cm soil layer (Shagalova et al. vide Kabata-Pendias 2011). Because 90 Sr
is easily adsorbed by Fe hydroxides, it is also accumulated in Fe-rich soil horizons.
Plants easily uptake 90 Sr, similar to stable Sr, and therefore it is applied in studies
of its metabolism in plants (Tsukada et al. 2005). Some plants are proposed to be used
for phytoremediation of soil contaminated with Sr. Alamo switchgrass (Panicum virginatum) may accumulate up to 44% of the total Sr radionuclide contents of soils.
The transfer factor for 90 Sr, expressed as its ratio in fresh weight plants to concentrations in soils, varies highly and is calculated as follows: potato tubers, 0.4; vegetable leaves, 0.8; and vegetable roots, 20 (Kabata-Pendias and Pendias 1999). In soil
amendment with Ca, Mg, and K fertilizers, the phytoavailability of 90 Sr is inhibited.
45.7 HUMANS
The typical adult body burden of Sr is about 320 mg in the blood 30 μg/L, 35–140 mg/
kg in the bone, and 120–350 μg/kg in the tissue (Emsley 2011). The distribution of
absorbed Sr in the human body is similar to that of Ca, with approximately 99% found
in the skeleton. Strontium can be taken into the body by eating food (Table 45.2),
drinking water, or breathing air. Humans absorb some 11%–30% of ingested Sr. Its
highest concentrations occur in the bones and teeth (mean 115–138  mg/kg), with