Radioactivity concentrations in sediments on the coast of the Iranian province of Khuzestan in the Northern Persian Gulf

Gamma-ray spectrometric analyses were performed on sediment samples from the coast of Khuzestan province (south west of Iran, neighbor to Iraq and Kuwait) to study the concentration of natural as well as man-made radioactive sources. The coast of Khuzestan, which extends for ~400 km is mainly soft areas of mud flats within different ecosystems including river mouth, estuaries, creeps, and small bays. Suspended material from the Iranian rivers including Arvand (Karun), Bahmanshir, Jarrahi, and Zohreh has settled to form these extensive soft areas. Eighty three samples were taken at different points along the coast in undisturbed areas at intervals of about 5 km since Fall 2005 to Winter 2006. Collection was carried out during low-tide, where it was possible to collect sediments from the wet region that was covered by sea water during the high tide. At each of the sample sites, a sampling area of about 1 m² was considered. All samples were of a muddy nature, and were left to dry in open air before drying in the oven at 105°C for 2-3 days to remove all water content. The average activity concentration of the radionuclides ²²⁶Ra (30 Bq/Kg), ²³²Th (11 Bq/kg), ²³⁸U (18 Bq/kg), and ¹³⁷Cs (2.6 Bq/kg) along the shore of Khuzestan reaches are much less than the values commonly assigned as the world average. Nevertheless in case of ⁴⁰K which is a long lived naturally occurring radionuclide, the result (481 Bq/kg) was higher than the world average which could be due to a large Kuwaiti oil spill and also fallout and deposition of tremendous amount of fly ashes which resulted from ignited Kuwaiti oil fields during the 2nd Persian Gulf war (1990-91). For man-made ¹³⁷Cs and naturally occurring ²³²Th, the western and eastern parts of Khuzestan shore showed higher concentrations than the middle part (Khooriat or creeps). For the long lived naturally occurring radionuclide ⁴⁰K and Gulf war ²³⁸U (anti armor shells), there were no significant differences (P < 0.05) among the three regions.