Marine environmental radioactivity off Namibia’s coast

Trabajo presentado a la 4th International Conference on Environmental Radioactivity: Radionuclides as Tracers of Environmental Processes, celebrada en Vilnius (Lithuania) del 29 de mayo al 2 de junio de 2017.-- et al.The International Atomic Energy Agency’s Environment Laboratories in Monaco (IAEA, NAEL) are supporting Member States (MSs) in understanding the marine environment by applying isotopic and nuclear techniques. In this context NAEL may take part in scientific cruises with the aim to assist MSs in marine radioactivity monitoring and assessment.This work was supported by the IAEA, NAEL Monaco and the Ministry of Fisheries and Marine Resources (MFMR), NamibiaPeer reviewe

Tracing the upwelling process in the northern Benguela upwelling system (nBUS) by 129I

New data on the presence of I in seawater in the Southern Hemisphere measured by Accelerator Mass Spectrometry (AMS) is presented. The samples were collected in 2014 along the Namibian coast during a cruise organised by the National Marine Information and Research Centre (NatMIRC), the national laboratories of the Ministry of Fisheries and Marine Resources (MFMR) in Namibia, and the IAEA Environment Laboratories (IAEA NAEL) in Monaco. The Benguela upwelling system is known as one of the most important marine upwelling regions in the world. Strong winds induce an offshore transport of surface seawater which is substituted by cool subsurface water inshore. As this water is nutrient-rich, which leads to high primary productivity, the Benguela upwelling system has a very important role as a fishing production area. The I concentrations in samples were between (0.66 ± 0.14) × 10 and (1.45 ± 0.30) × 10 atoms/kg. The highest I concentrations were found in the offshore surface samples. Deep-sea and inshore samples contained lower I concentrations, possibly as an effect of the upwelling process. A comparison with previously published studies suggests that the presence of I in the northern Benguela upwelling system (nBUS), is mainly due to the impact of nuclear weapons global fallout, without any evident impact of nuclear fuel reprocessing.This research has been partially financed by the project PGC2018-094546-B-I00 by the Spanish Ministerio de Ciencia, Innovación y Universidades

236U at the Centro Nacional de Aceleradores: first environmental studies

Trabajo presentado al VIII CPAN Days: Encuentros en Física Nuclear, celebrado en Zaragoza del 28 al 30 de noviembre de 2016.236U(T1/2=2.342·107 y) has mainly an anthropogenic origin and it has been present in the general environment since 1945 as a result of the development of the nuclear energy.Peer Reviewe

From radiometry to chronology of a marine sediment core: A 210Pb dating interlaboratory comparison exercise organised by the IAEA

Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and 210Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of 210Pb sediment dating technique within the framework of the IAEA Coordinated Research Project. The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable 210Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation. The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing 210Pb dating methods and identified some limitations in providing reliable chronologies.This work was supported by the International Atomic Energy Agency (IAEA) Coordinated Research project “Study of Global Temporal Trends of Pollution in Selected Coastal Areas by the Application of Isotopic and Nuclear Tools” (CRP K41016).Peer reviewe

Challenges and limitations of the 210Pb sediment dating method: Results from an IAEA modelling interlaboratory comparison exercise

The paper is a collective effort of participants in IAEA's CRP K41016 and their respective teams.The 210Pb sediment dating is the most widely used method to determine recent (~100–150 years) chronologies and sediment accumulation rates in aquatic environments and has been used effectively for reconstruction of diverse environmental processes associated with global change. Owing to the relative accessibility of the 210Pb methodology, many environmental chronologies have been produced, but not always critically assessed. Sometimes, sedimentary processes such as compaction, local mixing, erosion, or episodic sedimentation are not taken into account, nor the validity of the fundamental premises and proper estimation of uncertainties assessed. A Pb-210 dating interlaboratory comparison modelling exercise was designed within the framework of the IAEA (International Atomic Energy Agency) Coordinated Research Project “Study of temporal trends of pollution in selected coastal areas by the application of isotopic and nuclear tools” (CRP K41016), to identify potential problems associated with the use of 210Pb dating models and to suggest best practices to obtain reliable reconstructions. The exercise involved 14 laboratories worldwide with different levels of expertise in the application of the 210Pb dating methods. The dating exercise was performed using 210Pb, 226Ra and 137Cs activity data from two sediment cores (coastal and lacustrine sediments), and the participants were requested to provide their 210Pb chronologies based on dating models. This modelling exercise evidenced the limitations and constraints of 210Pb method when supplementary and validation information is not available. The exercise highlighted the relevance of solid understanding of the fundamentals, assumptions and limitations of the 210Pb dating method and its validation, and allowed identifying key aspects to improve the reliability of 210Pb dating process, including: a critical examination and interpretation of the 210Pb activity depth profile; an appropriate selection of the 210Pb dating model according to the characteristics of the 210Pb activity profile and the environmental setting taking into account sediment compaction in the calculations; a sound identification of the 210Pb equilibrium depth and the estimation of the 210Pb inventory ensuring the best possible estimation of interpolated 210Pb values when needed; and the use of independent markers to corroborate the age models.The IAEA is grateful to the Government of the Principality of Monaco for the support provided to its Environment Laboratories. This work has been supported by the IAEA Coordinated Research project “Study of Global Temporal Trends of Pollution in Selected Coastal Areas by the Application of Isotopic and Nuclear Tools” (CRP K41016).Peer reviewe