Contour Maps Description of Natural Radiation in The Soil of Najaf Province

Abstract

The soil is one of the most important natural sources of ionizing radiation to which humans are exposed. Naturally, radionuclides such as 238U series,232Th series and potassium 40K radioisotope are widespread in the soil and are considered the main sources the terrestrial natural radiation. The study under investigation is regarded as one of the rare studies that deals with the effect of the contents of the radionuclides on levels of natural radiation, besides being helpful in drawing of radiological maps for the area under study. The gamma radiation has been measured to determine 238U, 232Th and 40K natural radioactivity in the soil of selected area in Najaf city, south western part of Iraq. Google Earth program was used to get an upper view picture or photo of the area of study. In addition to this photo, our study involved maps that supported by the center of engineering affairs in the University of Kufa to get a geographical location of area under the study. As soil surface samples, 30 soil samples were obtained in a methodical manner. These samples were investigated using gamma-ray spectrometry, which included a high-counting-efficiency NaI (Tl) detector with a 2"×2" crystal dimension linked to the amplifier via a unit of preamplifier, an analog to digital converter (ADC), and a multichannel analyzer (MCA) with 4096 Cassy type channels. The findings of our research were shown in contoured radiological maps and analyzed using the Gaussian frequency distribution. Finally, all radiation results in the area of study were lower than limits of the global average, and they were also compared to the values recommended by international authorities and 40determined to be within permissible limits