Vol.:(0123456789) 1 3 Journal of Radioanalytical and Nuclear Chemistry https://doi.org/10.1007/s10967-019-06739-8 210 Pb and  137 Cs based techniques for the estimation of sediment chronologies and sediment rates in the Anzali Lagoon, Caspian Sea A. Abbasi 1 Received: 5 April 2019 © Akadémiai Kiadó, Budapest, Hungary 2019 Abstract 137 Cs and 210 Pb based sediment chronology methods, along with an HPGe gamma-ray spectrometry system, were applied to estimating of sediment accumulative rates (SAR), sedimentation rate (SR) and sedimentation chronology in the Anzali Lagoon. Sedimentation chronology was calculated according to the 210 Pb ex based-models including; the constant rate of supply, constant initial concentration and 137 Cs peak-technique. The SAR value were ranged from 0.12 g cm −2  year −1 in core-2 to 0.21 g cm −2  year −1 in core-3. The results showed that the average of SR and SAR values after 1986; interval were 22% and 54% more than between 1963 and 1986 intervals. Keywords 137 Cs · 210 Pb · Dating method · Sediment rates (SR) · Sediment accumulative rate (SAR) Introduction Sediment history in the lagoons and large lakes can pro- vide information about environmental changes, and shows chronological records in sediment layers [1–3]. The varve chronologies-based methods are applied to determine sedi- ment chronology. For younger sediment than 100–120 years, Lead-210 ( 210 Pb, T 1/2 = 22.3 years) dating method is com- mon. This method include the constant rate of supply (CRS) model and constant initial concentration (CIC) model [4]. Another dating method is 137 Cs based method that derived from nuclear fallout studies [5]. The man-made radioisotope of 137 Cs ( T 1∕2 = 30.17 years) produced in nuclear fssion reactions has entered into the atmosphere in irregularly varying amounts since 1945 [6, 7]. Nuclear accidents such as the Chernobyl accident and atmospheric nuclear weapons testing of the 1950s released large amounts of fssion product like 137 Cs into the environ- ment [8]. Considering the 137 Cs half-life, makes it’s as measurable tracer in the early 1950s, so sediment profle in a core along with 137 Cs detectable activity has chronology application [9, 10]. In practical studies, 137 Cs distributions in sediments profle derived from atmospheric nuclear weapons testing in the 1960s and the Chernobyl accident in 1986 were used as time markers to calculate sediment accumulation rates in lakes and reservoirs [11–14]. Determination of the sedimen- tation rates with the 137 Cs and 210 Pb method is suitable for sediments of up to 100 -120 years old [15–17]. Today it is accepted that two major challenge of global warming and land use change have caused significant changes of sediment distribution rates within the diferent parts of the fuvial system during recent decades. Schumm [18] divided a fuvial system into three zones: an upland erosion zone, a transportation zone and a sedimentation zone. Climate changing and/or human activities may result in changes in erosion and transportation processes in the frst two zones, and these will infuence the sedimentation rate in the third zone [19]. In this research, due to recent concerns about unusual changes of the Anzali Lagoon ecosystem, with emphasizes the effects of short-term natural changes in the coastal lagoons about anthropogenic efects, and demonstrates that rapid change is not only due to human action but also due to rapid sea-level change (Fig. 1). The hypothesis of this research was an investigation of sediment age of the Anzali Lagoon to determine entering and displaced sediment rate in Lagoon. By understanding the annual sedimentation rate, this can provide suitable planning for the lagoon conserva- tion and sediment management. For this reason, we apply the sedimentary analyses method in the Anzali Lagoon. For * A. Abbasi akbar.abbasi@emu.edu.tr; akbar.abbasi@kyrenia.edu.tr 1 Faculty of Engineering, University of Kyrenia, TRNC, Via Mersin 10, Turkey