Environmental Geochemistry of some Heavy Metals and the Radioactivity in Urban Subsurface Soils, Southeast-Baghdad

A geochemical evaluation was performed to determine the occurrences of many heavy metals as well as their natural activities, in the southeast-Baghdad.  For this purpose, seventeen subsurface soil samples from the cited location were collected at a depth of 50-100 cm. Samples collection included many types of land uses such as open space, roadside, green land, industrial and commercial samples. The samples were characterized systematically using XRF and gamma-ray spectrometry with NaI (Tl) scintillation detector. The total average concentrations of heavy metals Ag, Sn, Sb, I, Hf, W, Th and U in the soil were 1.94, 3.13, 3.01, 2.82, 1.70, 72,5.66 and 0.85 ppm respectively. Heavy metals Sn, I and W appeared with high concentrations among the others as shown in total average, compared with the standard. The enrichment with Sn elements strictly appeared in green and commercial lands with an average 3.63 ppm, whereas I and W concentrated in industrial land 3.0 and 0.95 ppm respectively, indicating anthropogenic rather than autogenic. It was asserted that the observed elements can be used as pollution indicators to discover the state of the contamination. The EF values of the soils in some sites displayed enrichment with Sb and moderate with Ag reflected mild enrichment (EF > 2), confirming their level of pollution by the hazardous heavy metals. The contents of 238U, 232Th and 40K in the samples varied from 34.64-48.54, 47.22-67.73, and 323.27-585.11 Bq/kg, respectively. The mean activities of 238U, 232Th and 40K in the dry weight samples were correspondingly 41.25, 56.89, and 424.12 Bq/kg, which were higher than the global averages of 35, 30 and 400 Bq/kg, respectively. The radium equivalent levels in all samples were much lower than the global average (370 Bq/kg). In addition, all external and internal hazard indices were within the recommended limit. The average dose rate and gamma index levels were greater than the global average value.