The influence of moisture deficiency on the content of trace elements and toxic substances in soils

Abstract

Objective: To determine the mobility of ions of trace elements, heavy metals, radionuclides, and pesticide residues under conditions of lack of soil moisture.
Methods. 6 test plots of 4 m2 each were selected in the following sequence: sod-podzolic sandy soil; sod-podzolic sandy soil; gray podzolic sandy soil; gray podzolic sandy soil; chernozem podzolic sandy soil; chernozem podzolic sandy soil. Within each test plot, soil samples were taken at the end of April to determine the moisture content and the content of trace element ions, heavy metals, radionuclides, and pesticide residues.
Results. Our studies have proven that under conditions of soil moisture change, the most useful for plants calcium ions – 12.31 mg-eq./100 g, magnesium – 1.07 mg-eq./100 g, mobile zinc – 0.55 mg/kg accumulate in podzolized sandy chernozem with the highest soil moisture – 10.3%. The most harmful cadmium – 0.08 mg/kg, lead – 1.45 mg/kg, radioactive cesium – 0.18 Ci/km2 and strontium – 0.014 Ci/km2 were found in sod-podzolic sandy soil, which had the lowest moisture content – 5.1%. The highest levels of sulfur and iron were found in sod-podzolic sandy loam soil – 10.7 mg/kg and 56.21 mg/kg, respectively, with a moisture content of 5.6%, and copper (1.62 mg/kg) and manganese (25.2 mg/kg) – in gray podzolic sandy loam soil with a moisture content of 7.5%.
Conclusions. It was found that changes in soil moisture have a direct effect on the content of exchangeable calcium, mobile magnesium, mobile zinc and mobile lead, as well as radioactive cesium and strontium. No effect of soil moisture on the content of mobile forms of sulfur, copper, manganese, iron and the heavy metal cadmium was found. As soil moisture decreases, the content of calcium (correlation coefficient r = 0.9669), magnesium (correlation coefficient r = 0.9819), zinc (correlation coefficient r = 0.7765) decreases, but the content of mobile forms of the heavy metal lead (correlation coefficient r = – 0.8209), radioactive cesium (correlation coefficient r = – 0.8628) and strontium (correlation coefficient r = – 0.8305) increases.