Radionuclide and trace elements geochemistry of the Urmia Lake Shore of Iran

Urmia Lake is one of the greatest salt lakes in the world and is located in the uppermost northwestern regions of Iran. In this study, in addition to trace elements, activity concentration of natural (238U, 232Th and 40K) and artificial (137Cs) radioisotopes are determined in soil and sediment specimens collected from the Urmia Lake shore by adopting gamma ray spectrometry method. The samples are analyzed for trace elements including heavy metals using atomic absorption and ICP-MS techniques. The activity concentration levels were determined for 238U (from 8 to 48 Bq kg−1), 232Th (from 7 to 64 Bq kg−1), 40K (from ≤ MDA to 631 Bq kg−1) and 137Cs (from ≤ MDA to 22 Bq kg−1) with the minimum detectable activity (MDA) of 5, 4, 63 and 4 Bq kg−1, respectively. It seems that except for the cadmium, all of the elements belong to uncontaminated to low contaminated soils group. The least correlation between 137Cs and other elements distribution in the area, confirms its anthropogenic man made source. Based on the cluster and factor analysis methods of data processing, 238U, 232Th and 40K belong to a similar group which in addition to their low geo-accumulation indexes can point to their geogenic sources, related to potassic volcanic rocks. Rare earth elements studies revealed that the main geochemical features of the sediment samples of the lake are affected by the intermediate to felsic Cenozoic volcano-plutonic rocks of the region.