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  • Author or Editor: H. Terzi x
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The effect of different chromium [Cr(VI)] concentrations (0, 75, 150 and 225 μM) on dehydrogenase activity, total soluble protein, proline, malondialdehyde (MDA) and antioxidant enzymes was investigated in the roots of two barley cultivars (Cr-tolerant Zeynelağa and Cr-sensitive Orza-96) in hydroponic experiments. The root dehydrogenase activity and protein content decreased with an increase in the Cr(VI) concentration, but no significant difference was found between the two barley cultivars. Cr(VI) stress increased the contents of proline and MDA in both cultivars, but this effect was more pronounced in Orza-96 than in Zeynelağa. The activities of antioxidant enzymes, including superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (POD), exhibited changes. The SOD activity increased in Zeynelağa and decreased in Orza-96 at 225 μM Cr(VI) compared to their controls. Cr(VI) stress decreased the APX and POD activities. Zeynelağa had greater APX activity than Orza-96 at 150 and 225 μM Cr(VI). However, there was no marked difference in POD activities between the two cultivars. The decrease in root dehydrogenase activity and protein content, the increase in proline and lipid peroxidation, and the alterations in the activities of antioxidant enzymes may be indicative of oxidative stress induced by Cr(VI).

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Abstract  

This study is part of an effort to assess the level of background radiation for Erzincan Province of eastern Turkey. Radionuclide activity concentrations in soil samples were measured through gamma-ray spectrometry and the average activities were determined as 8.93, 11.39, 281.94, and 9.52 Bq/kg for the radionuclides 238U, 232Th, 40K, and 137Cs, respectively. The average annual effective dose from these natural radioactivity sources (238U series, 232Th series and 40K,) was calculated to be 27.9 μSv. Radioactivity levels in drinking and potable water samples were studied using a multi-channel low level proportional counter. The average gross alpha activity concentration was found to be 0.0477 Bq/L (min. 0.007 Bq/L; max. 0.421 Bq/L) and the average gross beta activity was measured as 0.104 Bq/L (min. 0.008 Bq/L; max. 1.806 Bq/L). These values lead to an average annual effective dose of 9.75 μSv from the alpha emitters and 56.34 μSv from the beta emitting radionuclides in water. The radioactivity levels in the water samples investigated were found to comply with the reference levels recommended by WHO and the regulations set forth by the Turkish Health Ministry.

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