Assessment of the effects of physical–chemical parameters on 210 Po and 210 Pb concentrations in cultivated and uncultivated soil from different areas Banu Özden a, ⁎, Aysun Uğur a , Tolga Esetlili b , Bihter Çolak Esetlili b , Yusuf Kurucu b a Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir, Turkey b Ege University, Faculty of Agriculture, Soil Sciences Department, 35100 Bornova, İzmir, Turkey abstract article info Article history: Received 31 January 2012 Received in revised form 6 July 2012 Accepted 26 August 2012 Available online 16 November 2012 Keywords: 210 Po 210 Pb Soil properties Gediz Basin In this study, a total of 144 bulk soil samples were collected in cultivated and uncultivated sites in different areas for evaluation of the activity concentrations of 210 Po and 210 Pb. Moreover, 4 core samples were collect- ed from four distinct reference points in the Gediz Basin in Turkey and investigated organic matter content, 210 Po and 210 Pb concentrations depending on the depth. The activity concentrations of 210 Po and 210 Pb were measured by means of alpha spectrometry. While the activity concentrations of 210 Po and 210 Pb in cultivated sites are in the ranges of 12 ± 3–86±4 Bq kg -1 dw and 17 ± 3–36±3 Bq kg -1 dw, for uncultivated sites the ranges for 210 Po and 210 Pb are 10±4–134±21 Bq kg -1 dw and 23 ± 3–78±5 Bq kg -1 dw, respectively. In general, it is observed that the mean 210 Po and 210 Pb activity concentrations in cultivated sites are lower than the uncultivated sites. The relationships between soil properties and the activity concentrations of the radio- nuclides indicate that 210 Po and 210 Pb adsorption to soil is strongly related to organic matter content of the soil. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The adsorption of radionuclides on soil is affected by various fac- tors including changes in soil properties and type. Determination of the physico-chemical parameters such as pH, organic matter and soil texture in soil is one of the important aspects to understand transport of radionuclides in the environment (Guo et al., 2008; Hillel, 2004; Wasserman et al., 2008). Due to a large number of soil properties, types, climatic and topographical conditions at the studied sites, the relationships between soil characteristics and radionuclides are difficult to generalize beyond the studied domain. The natural radionuclides 210 Po and 210 Pb, with half-lives of 138 days and 22.3 years respectively, originate from the radioactive decay of radionuclides of 238 U series present in the earth's crust (supported). 210 Po and 210 Pb in the atmosphere and surface environ- ment originate from the decay of 222 Rn exhaled from the ground into the atmosphere. These radionuclides return to the earth surface as a result of dry fallout or are washed out in rain (unsupported). 210 Po and 210 Pb are also built up artificially in the environment due to waste discharge from phosphate, oil, and gas industries, combustion of fossil fuels and other energy production as technically enhanced natural radionuclides (Akyil et al., 2008; Fujiyoshi and Sawamura, 2004; Jia et al., 2006; Martinez-Aguirre and Garcia-Leon, 1997; Navas et al., 2011; Persson and Holm, 2011; Sert et al., 2011; Uğur et al., 2003). 210 Po and 210 Pb are important from a radioecological point of view. These radionuclides have been widely used in studies of atmospheric, marine and terrestrial environments (Akyil et al., 2008; Aslani et al., 2005; Matthews et al., 2007; Narayana and Rajashekara, 2010; Persson and Holm, 2011; Sert et al., 2011; Uğur et al., 2011a, 2011b). Upon reaching the soil surface as fallout from the atmosphere, 210 Po and 210 Pb are rapidly and strongly adsorbed by the surface soil (Jia et al., 2006; Parfenov, 1974; Walling and He, 1999). Gediz Basin is an important region for assessing and monitoring soil properties impacts on soil erosion. Changes in soil properties may affect vegetation and erosion rate. Measurements of the physico-chemical parameters in soils can improve the interpretation of measured erosion rate and explain the differences in erosion rates among the catchments. The objectives of this study are to (i) describe the main physical and chemical parameters of soils as a reference for future monitoring activities, (ii) investigate the effect of soil texture and organic matter on the distribution and mobility of 210 Po and 210 Pb, and (iii) assess the relationships between the soil characteristics and natural radio- nuclides for both cultivated and uncultivated areas. 2. Materials and methods 2.1. The study area Gediz Basin, located in western Turkey, covers an area of some 17,000 km 2 , involving 140,000 ha of irrigated area. The sampling sites in Gediz Basin have been selected on the basis of the one of Geoderma 192 (2013) 7–11 ⁎ Corresponding author. Tel.: +90 232 3113454; fax: +90 232 3113433. E-mail address: ozdenbanu@yahoo.com (B. Özden). 0016-7061/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.geoderma.2012.08.025 Contents lists available at SciVerse ScienceDirect Geoderma journal homepage: www.elsevier.com/locate/geoderma