Radionuclides and recent sedimentation and mixing rates in Northern Gulf of Eilat/Aqaba, Red Sea

Natural radionuclides and man-made Cs-137 were analyzed in five short sediment cores taken in northern part of the Gulf of Eilat (Gulf of Aqaba) in order to provide information on sedimentation and mixing rates and sediment sources. The maximum estimates of sedimentation rates based on excess Pb-210 were found to vary between 0.105 +/- 0.020 and 0.35 +/- 0.23 cm.year(-1). Even the lowest estimates are significantly higher than those expected from dust deposition, suggesting other sources and processes being responsible for most of the allochthonous material accumulation, including periodical floods following heavy rain events, internal erosion or triggers, like earthquakes. In Cs-137 depth profiles no 1963 related nuclear weapon test maxima were found; instead, the activities decrease monotonically, suggesting that a major process leading to radionuclides' depth distribution might be mixing. The mixing rates calculated from Cs-137, excess Pb-210 and excess Th-228 reach values up to 2.18 +/- 0.69 cm(2).year(-1). (C) 2014 Elsevier B.V. All rights reserved.