A study about radiation dosimetry and heavy metal pollution in the Küçük Menderes Basin, Turkey (Radio-ecological and Heavy Metal Risks)

Abstract

Agricultural researchers in many countries investigate radiological risks in soil and crops because it concerns human health. In addition, they also study heavy metal pollution in plants in cultivated soil for ecological safety. This study aims to analyze the activity concentrations of radionuclides and heavy metals in soil and corn crops in the Küçük Menderes Basin (Izmir, Turkey) – which is enriched with phosphatic fertilizers. We collected soil and corn samples from the area, and then separately measured concentrations of radionuclides (226Ra, 232Th and 40K) and trace elements (Cd, Cr, Cu, Hg, Ni, Pb and Zn) they contain. Activity concentrations of the radionuclides were acquired by radiometric methods (gamma spectroscopy). Heavy metal amounts were calculated using ICP-MS (inductively coupled plasma-mass-spectrometry). The mean heavy metal concentrations in the soil (Cd, Cr, Cu, Zn, Ni, Pb, Hg) were 0.096, 40.26, 26.51, 72.43, 32.24, 7.05 mg kg-1, 158.28 µg kg-1 and in the corn (Cd, Cr, Cu, Zn, Ni, Pb, Hg) were 0.01, 1.09, 2.05, 22.00, 0.54, 0.24 mg kg-1, 12.15 µg kg-1. The heavy metal concentrations in soil samples were as follows: Hg < Cd < Pb < Cu < Ni < Cr < Zn and in corn samples were as follows: Hg < Cd < Pb < Ni < Cr < Cu < Zn. Also, the mean activity concentrations in the soils (226Ra, 232Th, 40K) were 36.2±2, 32±1, 615.44±7 Bq kg-1. The 226Ra and 232Th concentrations in the corn samples are smaller than the Minimum Detectable Activity (MDA). However, the mean activity concentration of 40K in the corn samples is 310.7±8 Bq kg-1. These values considered are acceptable for human health according to UNSCEAR (2000). The heavy metal concentrations in the soil and corn samples are within acceptable limits for Turkish Government. The level of radionuclide activity and heavy metal concentrations, as well as both transfer and bio-concentration factors are comparable with those of a handful of other countries. Long-term research on radio-ecological risks is very important for agricultural control. In addition, the data set of radiation levels and pollutant elements do not have a fixed amount in related materials such as soil and plants. On the other hand, the quantity of pollutants soil (via plants) has risen due to activity from non-controlled industrial facilities. Researchers and governments alike therefore must monitor ecological pollution of terrestrial radionuclides and heavy elements on a routine basis.

Keywords

• radioecology
• agronomy
• heavy metals
• soil
• corn