Plutonium and cesium baseline concentrations in seawater from northern Arabian Gulf

The Arabian Gulf is a semi-enclosed water body that has witnessed accelerated anthropogenic activity, in terms of commissioning of nuclear power plants, desalination facilities, oil refineries and extensive coastal development. Furthermore, three wars during the past three decades is a potential worry. This study presents the first plutonium baseline in seawater from the Northern Arabian Gulf. The ^239+240Pu concentrations in seawater vary, between 2.9 and 4.9mBqm^-3, a range that is comparable to other water masses at this latitude. The ²³⁸Pu ranged between 0.04 and 0.05mBqm^-3 and the ¹³⁷Cs concentration between 1.04 and 1.18Bqm^-3. The ratio of ²³⁸Pu/^239+240Pu at all eight sampling stations was 0.01, while the ratio of ^239+240Pu/¹³⁷Cs varied between 0.01 and 0.02. The presence of ¹³⁷Cs and ^239+240Pu in seawater from this region can mainly be attributed to the global atmospheric deposition and fluvial transport. The seawater concentration of ^239+240Pu is five order of magnitude lower than bottom sediments in the area.