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Dataset published as supplementary material of Chamizo et al. (2022), http://doi.org/10.1029/2021JC017790. This supporting material includes two Texts with further explanations on two points given in the manuscript: Text 1 explains the calculations used to model the input function of the 233U/236U ratio in the Atlantic Layer of the Arctic Ocean; Text 2 presents the adopted calculations to estimate the 233U/236U ratio in the surface of the rocks due to natural production processes, and the adopted number for the U present in Deep and Bottom Waters in the Amerasian Basin. Figure S1 compares the obtained ICP-MS 238U results in this work with the predicted ones based on salinity data using the empirical formula given in (Owens et al., 2011). Figure S2 shows how the modelled 233U/236U ratios for the Atlantic Layer in Text 2 compares with the obtained values in this work.

Plutonium distribution was studied in an undisturbed sediment core sampled from the Tvaren bay in the vicinity of the Studsvik nuclear facility in Sweden. The complete analysis, including minor isotopes, of the Pu isotope composition (238Pu, 239Pu, oPu, 241Pu, 242Pu, and 244Pu) allowed us to establish the Pu origin in this area of the Baltic Sea and to reconstruct the Studsvik aquatic release history. The results show highly enriched 239Pu, probably originating from the Swedish nuclear program in the 1960s and 1970s and the handling of high burn-up nuclear fuel in the later years. In addition, the 244Pu/239Pu atomic ratio for the global fallout period between 1958 and 1965 is suggested to be (7.94 +/- 0.31)center dot 10-5. In the bottom layer of the sediment, dated 1953-1957, we detected a higher average 244Pu/239Pu ratio of (1.51 +/- 0.11)center dot 10-4, indicating the possible impact of the first US thermonuclear tests (1952-1958)., Funding Agencies|Swedish Radiation Safety Authority (SSM) [SSM2020-643]; Spanish Goverment (Ministerio de Ciencia, Innovaci?n y Universidades) [PGC2018-094546-B-I00]

U (T = 0.159 My) has aroused much interest in the last few years because of the potential of U/U to inform about anthropogenic U sources. The reported U/U atom ratios in general environmental samples are in the 10–10 range. We demonstrate that U/U abundance sensitivities at the 5 × 10 level can be achieved at the 1 MV Accelerator Mass Spectrometry system at the Centro Nacional de Aceleradores (CNA, Seville, Spain). Unresolved U, U and Th molecular fragments are identified as the main U background contributors and procedures to subtract them are proposed. U/U and U/U atom ratios were analysed in the IAEA reference materials coded Soil-6, 300, 385, 410, and 412 at the CNA and at the 600 kV ETH AMS system for intercomparison. U/U atom ratios for samples 412 and 385 were only reported by the ETH.

This study explores for the first time the possibilities that the U/U atom ratio offers to distinguish waters of Atlantic or Pacific origin in the Arctic Ocean. Atlantic waters entering the Arctic Ocean often carry an isotopic signature dominantly originating from European reprocessing facilities with some smaller contribution from global fallout nuclides, whereas northern Pacific waters are labeled with nuclides released during the atmospheric nuclear testing period only. In the Arctic Ocean, U originates from global fallout while U carries both, a global fallout and a prominent nuclear reprocessing signal. Thus, the U/U ratio provides a tool to identify water masses with distinct U sources. In this work, U and U were analyzed in samples from the GN01 GEOTRACES expedition to the western Arctic Ocean in 2015. The study of depth profiles and surface seawater samples shows that: (a) Pacific and Atlantic waters show enhanced signals of both radionuclides, which can be unraveled based on their U/U signature; and (b) Deep and Bottom Waters show extremely low U and U concentrations close to or below analytical detection limits with isotopic ratios distinct from known anthropogenic U sources. The comparably high U/U ratios are interpreted as a relative increase of naturally occurring U and U and thus for gradually reaching natural U/U levels in the deep Arctic Ocean. Our results set the basis for future studies using the U/U ratio to distinguish anthropogenic and pre-anthropogenic U in the Arctic Ocean and beyond.

A baseline study on anthropogenic radioactivity in the Namibian marine ecosystem, which is part of the northern Benguela upwelling system, known as one of the most productive ocean areas in the world, has been performed. A scientific cruise carried out in 2014 covering inshore and offshore areas, exhibiting different oceanographic features, has provided a basis for better understanding the distributions, ratios and inventories of six anthropogenic radionuclides (Sr, Cs, Pu, Pu, Pu and Am) in seawater. Although H was also measured, due to extremely low levels, its behaviour was not studied. The main source of Sr, Cs, Pu, Pu and Am in the samples analysed was proven to be global fallout, a finding further confirmed by Pu/Pu and Sr/Cs ratios. Furthermore, the Pu SNAP-9A satellite accident signal was confirmed once again through the determination of the Pu/Pu activity ratio. Inshore and offshore samples showed different patterns due to the unique oceanographic features of this upwelling system. The levels of anthropogenic radionuclides, comprehensively assessed for the first time in this region, are comparable with the few existing data and filled a critical gap for the Southern Atlantic Ocean.

A simple and fast radiochemical procedure for the sequential extraction of U, Np and Pu from small-volume seawater samples (<10 L) is presented. The method has been developed and optimized for the final determination of 236U, 237Np, 239Pu and 240Pu by Accelerator Mass Spectrometry (AMS). It is based on the use of 242Pu as tracer for both Np and Pu isotopes. Samples are pre-concentrated by Fe(OH)2 co-precipitation. TEVA® and UTEVA® resins are used in a very simplified way for the final purification of the Pu+Np and U fractions, respectively. The radiochemical yields of the three elements have been investigated in detail by alpha spectrometry (AS) and gamma spectrometry (GS). The obtained results indicate high and robust chemical yields for the three elements and similar ones for Pu and Np. Furthermore, the use of 242Pu as tracer for 237Np is validated by analyzing a reference seawater sample (IAEA-443) by radiometric techniques. We demonstrated that, if chemicals are properly chosen, processed blank levels can be kept at the same level of the extremely low detection limits that can be achieved by AMS (105–106 atoms/sample). The procedure is finally applied for the study by AMS of a reference seawater sample from the Mediterranean Sea (IAEA-418).

In January 2015, the 1 MV AMS facility at the Centro Nacional de Aceleradores (CNA, Seville, Spain) was upgraded with He stripping. In this work, we present a comprehensive study of the uranium transmission through the accelerator together with the background sources that limit the current sensitivity of our system to measure the 236U/238U atom ratio. In addition to the well-known background caused by scattered 235U3+ molecular fragments, we identify an additional component, not observed with Ar gas, that we relate to scattered 238U3+ molecular fragments. Stripper gas pressures below the one corresponding to the equilibrium charge state distribution are used to minimize the resulting overall background, which is in the (0.8–1.3) × 10−10 range. This is at least a factor of 3 higher than the background obtained with Ar gas. On the other hand, new information on the stripping process of U on He gas at the 400–1000 keV stripping energy range is presented. A maximum transmission of 45% for U3+ is achieved at about 650 keV, which correspond to a stripping yield of about 50%. This is the maximum yield that can be actually obtained working with He gas at low energies according to previous results.

A new multi-isotope plutonium standard for isotopic ratio measurements with Accelerator Mass Spectrometry (AMS) was created by gravimetric mixing of different single-isotope standards provided by IRMM (Pu-239, Pu-240, Pu-242, Pu-244). This standard material has been measured at the AMS facilities at Canberra (Australia), Cologne (Germany), Caserta (Italy), Sevilla (Spain) and Zurich (Switzerland). Additionally, the material was characterized using a Neptune MC-ICPMS (multi-collector inductively coupled plasma mass spectrometry) at the joint Cologne-Bonn isotope facility. The results of this laboratory intercomparison are presented and consensus values for the isotope compositions of the standard material are proposed.

Low-energy Accelerator Mass Spectrometry (AMS) systems (i.e. working with 1 MV terminal voltages and below) have demonstrated in the past their capability for the ultra-trace analyses of U and Pu in different field studies. The situation for Np has been different, mostly due to the constraints imposed by the lack of a Np isotopic tracer. Here, it is presented a comprehensive study on the performance of the 1 MV AMS system at the Centro Nacional de Aceleradores (CNA) for: i) the determination of Np using Pu as the AMS normalisation isotope and, ii) the efficient analysis of Pu, Pu and Np when they coexist in the same cathode with traces of natural uranium. Working procedures to analyse Np and Pu on one hand, and Pu on the other, are developed in order to meet competitive U suppression factors and counting efficiencies for every radionuclide. It is demonstrated that the sputtering-process-based temporal trend in the Np/Pu AMS ratios show a coherent behaviour between the different studied matrixes, demonstrating the reliability of the necessary standard correction procedure in AMS. It is proved that Np and Pu concentrations at the 1 fg level and Pu concentrations at the 0.1 fg level can be quantified in samples containing U traces. The technique is applied to the Pu and Np analysis of a seawater reference sample supplied by the International Atomic Energy Agency (IAEA): IAEA-443.

The passive absorber technique is one of the most common ways to suppress the 10B interference during 10Be measurements at facilities working with beam energies above 7 MeV. At lower energies, the range straggling complicates the application of absorbers, so that other suppression techniques are normally preferred. Several experiments were conducted at the SARA (hosted at Centro Nacional de Aceleradores, Seville, Spain) and VERA (Faculty of Physics, University of Vienna, Austria) AMS facilities to demonstrate the potential of the passive absorber technique also at and below 2.4 MeV. Two different absorber setups were installed and tested. For the detection of the rare isotopes both facilities used a gas ionization chamber optimized for light ions detection based on the same design. The absorber installed at the SARA facility was a combination of SiN foils and an isobutane gas volume, whereas VERA was equipped with an absorber constituted of a stack of SiN foils. In both cases, 10Be could be clearly separated from 10B and the use of a passive absorber at the entrance of the detector gave higher transmission compared to the degrader method. Depending on the absorber design, different background contributions could be identified: Rutherford scattering of 10B on the protons contained in the SiN foils and isobutane gas was responsible of a severe background at SARA, and fragments from 9Be1H molecules surviving the stripping process resulted in events partially overlapping the 10Be gate at VERA. The measured transmissions and background levels will be presented for the tested setups, as well as the advantages and disadvantages of each absorber design.

The aim of this study was to assess the potential of combining the conservatively behaving anthropogenic radionuclides U-236 and Np-237 to gain information on the origin of water masses tagged with liquid effluents from Nuclear Reprocessing Plants. This work includes samples collected from three full-depth water columns in two areas: i) the Arctic Ocean, where Atlantic waters carry the signal of Sellafield (United Kingdom) and La Hague (France) nuclear reprocessing facilities; and ii) the western Mediterranean Sea, directly impacted by Marcoule reprocessing plant (France). This work is complemented by the study of the particle-reactive Pu isotopes as an additional fingerprint of the source region. In the Canada Basin, Atlantic waters showed the highest concentrations and Np-237/U-236 ratios in agreement with the estimated values for North Atlantic waters entering the Arctic Ocean and tagged with the signal of European Nuclear Reprocessing Plants. These results may reflect the impact of the documented releases for the 1990s. In the Mediterranean Sea, an excess of U-236 presumably caused by Marcoule is reflected in the lower Np-237/U-236 ratios compared to the Global Fallout signal in all the studied samples. On the contrary, the Pu-239,Pu-240 profiles were mainly governed by the Global Fallout. The impact of Marcoule as a local source is further corroborated when comparing the temporal evolution of these ratios between 2001 and 2013. The lowest Np-237/U-236 ratios observed in 2001 at the surface reflect a previous local input that is no longer observed in 2013 as it had been homogenized through the whole water column. This work presents the use of Np-237 as a new ocean tracer. A more accurate characterization of the main sources is still needed to optimize the use of U-236-Np-237 as a new tool to understand transient oceanographic processes. (C) 2020 Elsevier B.V. All rights reserved., Funding Agencies|Spanish Government (Ministerio de Economia y Competitividad) [FIS2015-69673-P, PGC2018-094546-B-I00]; Spanish Government (Ministerio de Ciencia, Innovacion y Universidades) [FIS2015-69673-P, PGC2018-094546-B-I00]; U.S. National Science FoundationNational Science Foundation (NSF) [OCE 1439319]; Fundacion Camara Sevilla

The aim of this study was to assess the potential of combining the conservatively behaving anthropogenic radionuclides 236U and 237Np to gain information on the origin of water masses tagged with liquid effluents from Nuclear Reprocessing Plants. This work includes samples collected from three full-depth water columns in two areas: i) the Arctic Ocean, where Atlantic waters carry the signal of Sellafield (United Kingdom) and La Hague (France) nuclear reprocessing facilities; and ii) the western Mediterranean Sea, directly impacted by Marcoule reprocessing plant (France). This work is complemented by the study of the particle-reactive Pu isotopes as an additional fingerprint of the source region. In the Canada Basin, Atlantic waters showed the highest concentrations and 237Np/236U ratios in agreement with the estimated values for North Atlantic waters entering the Arctic Ocean and tagged with the signal of European Nuclear Reprocessing Plants. These results may reflect the impact of the documented releases for the 1990s. In the Mediterranean Sea, an excess of 236U presumably caused by Marcoule is reflected in the lower 237Np/236U ratios compared to the Global Fallout signal in all the studied samples. On the contrary, the 239,240Pu profiles were mainly governed by the Global Fallout. The impact of Marcoule as a local source is further corroborated when comparing the temporal evolution of these ratios between 2001 and 2013. The lowest 237Np/236U ratios observed in 2001 at the surface reflect a previous local input that is no longer observed in 2013 as it had been homogenized through the whole water column. This work presents the use of 237Np as a new ocean tracer. A more accurate characterization of the main sources is still needed to optimize the use of 236U-237Np as a new tool to understand transient oceanographic processes.

The Centro Nacional de Aceleradores is a user-oriented accelerator facility in Seville, Spain. Its main facilities are a 3 MV tandem accelerator, an 18 MeV proton Cyclotron, a tandetron used for AMS, a compact accelerator used for radiocarbon measurements, a Co irradiator and a PET/CT scanner. The technical specifications and research applications of these facilities are described. A neutron beam line associated to a charged pulsed beam in the tandem allows for time of flight measurements which determine the neutron energy. The use of an adequate stripper gas in the AMS tandetron permits to measure heavy radionuclides with very low detection levels, allowing to perform environmental studies using these radionuclides as tracers. The use of the microbeam in the tandem accelerator allows to apply the ion beam-induced current technique to investigate the spectroscopic properties and radiation hardness of different semiconductor detectors.

There are very few data available of 236U in marine sediment cores. In this study we present the results from the first oceanic depth profile of 236U in a sediment core sampled in the North Atlantic Ocean, at the PAP site (4500 m depth, Porcupine Abyssal Plain (PAP) site, 49°0′ N, 16°30′ W). Additionally, the sediment core was radiologically characterized through the measurement of anthropogenic 137Cs, 239Pu, 240Pu, 129I and 14C and natural 210Pb, 40K and 226Ra. The measured 236U concentrations decrease from about 90·106 at g−1 at the seafloor down to 0.5·106 at g−1 at 6 cm depth. They are several orders of magnitude lower than the reported values for soils from the Northern Hemisphere solely influenced by global fallout (i.e. from 2700·106 to 7500·106 at g−1). 236U/238U atom ratios measured are at least three orders of magnitude above the estimated level for the naturally occurring dissolved uranium. The obtained inventories are 1·1012 at m−2 for 236U, 80 Bq m−2 for 137Cs, 45 Bq m−2 for 239+240Pu and 2.6·1012 at m−2 for 129I. Atomic ratios for 236U/239Pu, 137Cs/236U and 129I/236U, obtained from the inventories are 0.036, 0.11 and 2.5 respectively. Concentration profiles show mobilization probably due to bioturbation from the abundant detritivore holothurian species living at the PAP site sea-floor. The range of 236U, 137Cs, 239+240Pu and 129I values, inventories and ratios of these anthropogenic radionuclides are more similar to the values due to fall-out than values from a contribution from the Nuclear Fuel Reprocessing Plants dispersed to the south-west of the North Atlantic Ocean. However, signs of an additional source are detected and might be associated to the nuclear wastes dumped on the Eastern North Atlantic Ocean.

236U, 239Pu and 240Pu are present in soils mainly as a result of the local- and global-fallout from the atmospheric nuclear weapons tests carried out mainly in the 1950's and 1960's. In this work we provide new data on the presence of 236U and 239,240Pu in surface soils (i.e. up to 5 cm depth) from Chile and Africa. The results were obtained by low-energy Accelerator Mass Spectrometry (AMS). In the case of the Chilean samples, 236U/239Pu atom ratios show a high variability and are in general higher than the reported value for the global fallout in the Northern Hemisphere, ranging from 0.2 to 1.5. The 236U atomic concentrations range from 3.5 × 106 to 9.1 × 106 atoms/g, and are at least two orders of magnitude lower than the reported values in the Northern Hemisphere. The measured 240Pu/239Pu atom ratio in soils from South-Africa and Mozambique are of about 0.17, in agreement with the expected one for global-fallout at those coordinates. To best knowledge of the authors the present work is the first publication on 236U concentrations and 236U/239Pu atom ratios in soils from South-America and Africa.

The Benguela Upwelling System (BUS), off the south-western African coast, is one of the four major eastern boundary upwelling ecosystems in the oceans. However, this area has been overlooked in the field of environmental radioactivity. In this work, 236U and 237Np were collected off the coast of Namibia within the northern BUS. Surface seawater exhibited similar 236U and 237Np concentrations, ranging from 3.9·106 to 5.6·106 atoms kg−1 and from 4.6·106 to 8.5·106 atoms kg−1, respectively. The observed inventories in a water column from the continental margin, of (2.10 ± 0.11)·1012 atoms m−2 for 236U and (3.48 ± 0.13)·1012 atoms m−2 for 237Np, were in agreement with the global fallout (GF) source term in the Southern Hemisphere that was the main source of actinides to the region. A pattern was observed in the surface samples, with 237Np concentrations that decreased by 25–30% when moving from inshore to offshore stations, but such an effect could not be clearly discerned in the case of 236U within the data uncertainties. An explanation based on the larger particle reactivity of GF 237Np compared to GF 236U was proposed. Such an effect would have been important at the studied site due to the enhance presence of particles in the continental shelf triggered by the upwelling phenomenon. A value of 1.77 ± 0.20 was obtained for the 237Np/236U atom ratio for the GF source term in the marine environment.

Continental dust can be suspended and transported by the wind, reaching seawater masses far away from its source. The deposition of the aerosols on the ocean surface can alter the abundance of chemical species in the water column and contribute to element inventories in seafloor sediments. A major Saharan dust intrusion into the Western Mediterranean Sea was recorded at the DYFAMED site (Ligurian Sea) in 20th February 2004. We determined the influence of this dust event on the concentration of 30 minor and trace level elements (TE) in sinking particles collected by sediment traps deployed at 200 m and 1000 m depth, and how a dust flux event like this contributed to the exchange of TE, including Fe, with the water column during major dust events. With coupled sediment traps and aerosol samples, we assessed the short-term implications of dust events in the water column. The event produced a flux of fast (>111 m d−1) and slow (<20 m d−1) sinking dust particles, detected during 3 weeks at 200 m and 4 weeks at 1000 m depth. Additionally, the obtained results of element concentrations and particles flux show that a single dust deposition event can produce a sinking flux equivalent to annual deposition rates of elements relevant to biogeochemical cycles and/or pollution studies: (>60% for Cr and Cu, >70% for Al, >80% for Ni and Zn, >90% for V and Mn, >100% for Fe and Pb). The corresponding Enrichment Factors (EF) for the minor and TE analyzed in the sediment traps during the dust event were calculated. EF was used to determine how minor and trace element concentrations in sinking particles vary. The values ranged between 0.35 and 421 in both 200 m and 1000 m sediment traps. For most of the analyzed elements, the obtained EF values were higher than 1. On the contrary, V, Y, Zr, Nb, and Ce showed EF ~ 1 while Cr, Ni, Cu, Zn, Sn, and Pb showed EF < 1. Despite the variability in the EF values, vertical fluxes integrated during the dust deposition event increased from 200 m to

This work provides new insights into the presence of 239Pu, 240Pu, 241Pu, and 236U in the Southern Hemisphere through the study of peat bog cores from marshlands in Madagascar (19°S). 210Pb, 238Pu and 239+240Pu activities were characterized by alpha spectrometry in previous studies. Here, Pu from alpha-spectrometry discs corresponding to 10 peat-bog cores (85 samples) was reassessed for the aim of completing its isotopic composition (239Pu, 240Pu, and 241Pu) by Accelerator Mass Spectrometry. In addition, 236U was studied in a single core exhibiting unusually low 240Pu/239Pu ratios. Integrated 240Pu/239Pu atom ratios in the single cores ranged above and below the (0–30°S) fallout average ratio, 0.173 ± 0.027, from 0.126 ± 0.003 to 0.206 ± 0.002, without a regional pattern, thereby demonstrating the heterogeneous distribution of the 239Pu and 240Pu signal. However, such a variability was not observed for 241Pu/239Pu, ranging from (6 ± 1) · 10−4 to (11 ± 1) · 10−4 and consistently below the (0–30°S) fallout ratio of (9.7 ± 0.3) · 10−4 (2012). The integrated 236U/239Pu atom ratio in the studied core, 0.147 ± 0.005, was also significantly lower than the values reported for the global fallout in the Northern Hemisphere, in the 0.20–0.23 range. Our results point out to stratospheric fallout as the main source of both 236U and 241Pu at the studied site, whereas 239Pu and 240Pu signals show the influence of tropospheric fallout from the low-yield tests conducted in Australia (1952–1958) by United Kingdom and in French Polynesia (1966–1975) by France despite the long relative distances (i.e. about 15,000 and 8500 km). It was also demonstrated that a representative number of samples is necessary in order to assess Pu contamination and its various origins in a specific region in the Southern Hemisphere due to the heterogeneous distribution, and results based on single sample analysis should be interpreted with caution.

In February 2004, anthropogenic radionuclides (137Cs, 236U, 239Pu and 240Pu), transported from the Sahara Desert, were observed in the Monaco air, and later in water and sediment samples collected at the DYFAMED site in the northwest (NW) Mediterranean Sea. While 236U and 137Cs in Saharan dust particles showed a high solubility in seawater, Pu isotopes were particle reactive in the water column and in the sediment. The impact of the Saharan deposition was found at 0–1.0 cm of the sediment core for 236U and 137Cs, and between 1.0 and 1.5 cm for Pu isotopes. The excess of 236U was observed more in the water column than in the sediment, whereas the 239+240Pu total inventories were comparable in the water column and the sediment. This single-day particle event represented 72% of annual atmospheric deposition in Monaco. At the DYFAMED site, it accounted for 10% (137Cs) and 15% (239+240Pu) activities of sinking particles during the period of the highest mass flux collected at the 200 and 1000 m water depths, and for a significant proportion of the total annual atmospheric input to the NW Mediterranean Sea (28–37% for 137Cs and 34–45% for 239+240Pu). Contributions to the total 137Cs and 239+240Pu sediment inventories were estimated to be 14% and 8%, respectively. The Saharan dust deposition phenomenon (atmospheric input, water column and sediment) offered a unique case to study origin and accumulation rates of radionuclides in the NW Mediterranean Sea.

Continental dust can be suspended and transported by the wind, reaching seawater masses far away from its source. The deposition of the aerosols on the ocean surface can alter the abundance of chemical species in the water column and contribute to element inventories in seafloor sediments. A major Saharan dust intrusion into the Western Mediterranean Sea was recorded at the DYFAMED site (Ligurian Sea) in 20th February 2004. We determined the influence of this dust event on the concentration of 30 minor and trace level elements (TE) in sinking particles collected by sediment traps deployed at 200 m and 1000 m depth, and how a dust flux event like this contributed to the exchange of TE, including Fe, with the water column during major dust events. With coupled sediment traps and aerosol samples, we assessed the short-term implications of dust events in the water column. The event produced a flux of fast (>111 m d(-1)) and slow ( < 20 m d(-1)) sinking dust particles, detected during 3 weeks at 200 m and 4 weeks at 1000 m depth. Additionally, the obtained results of element concentrations and particles flux show that a single dust deposition event can produce a sinking flux equivalent to annual deposition rates of elements relevant to biogeochemical cycles and/or pollution studies: (>60% for Cr and Cu, >70% for Al, > 80% for Ni and Zn, > 90% for V and Mn, > 100% for Fe and Pb). The corresponding Enrichment Factors (EF) for the minor and TE analyzed in the sediment traps during the dust event were calculated. EF was used to determine how minor and trace element concentrations in sinking particles vary. The values ranged between 0.35 and 421 in both 200 m and 1000 m sediment traps. For most of the analyzed elements, the obtained EF values were higher than 1. On the contrary, V, Y, Zr, Nb, and Ce showed EF similar to 1 while Cr, Ni, Cu, Zn, Sn, and Pb showed EF < 1. Despite the variability in the EF values, vertical f, Funding Agencies|Government of the Principality of Monaco