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Determination of the 36Cl and 129I massic activities using pyrolysis combined with radiochemical separation (using a Cl-resin) in concrete and graphite samples from decommissioning waste originating from Belgian Reactor 3 and 1 (SCK CEN, Belgium), respectively, is described. Liquid scintillation counting is used for their quantification. The chemical recovery of the procedure was evaluated by determining the stable chlorine with ion chromatography and stable iodine with inductively coupled plasma mass spectrometry. The method was optimized and verified by spiking inactive solid materials. [ABSTRACT FROM AUTHOR]

Abstract: PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9mgkg−1, 12ng TEQkg−1 and 5.1ng TEQkg−1. Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs. [Copyright &y& Elsevier]

Monitoring of uranium in the environment using the Diffusive Gradients in Thin-films (DGT) technique gains in importance as it can provide unique information about the bioavailability of the element and allows its long-term in-situ measurement. Hence, in this study, four DGT binding phases (Chelex-100, Dow-PIWBA, Diphonix, and Lewatit FO 36 resins) were evaluated for uranium monitoring to assess the robustness of their performance in estuarine and marine environments. These DGTs were deployed along the Scheldt estuary (Belgium and the Netherlands) over four campaigns between 2014 and 2021. The DGT performance (ratio of the DGT-determined vs. dissolved U concentration in grab water sample) varied with the water salinity. The Chelex-100 DGTs generally provided good performance in freshwater (median ratios close to 1.0), but an inverse correlation with the increasing salinity was observed (median ratios 0.7 at the stations with salinity >5). The Lewatit FO 36 DGTs provided good performance in the salinity range 0–18 (median ratios 1.0). However, a strong negative influence was observed at stations with high salinity levels (>18, ratio 0.6) and during the long-term deployment in seawater (ratios <0.5 over deployment periods ≥2 days). The Dow-PIWBA and Diphonix DGTs provided overall similar results with excellent performances along the whole salinity gradient (median ratios 1.1 and 1.0, respectively). Nevertheless, the long-term deployment trial in seawater (salinity ∼27) revealed the robustness of Diphonix DGTs that provided outstanding results even after 28 days of deployment (ratio 1.0). The differences in the performance of tested DGT resins were mostly given by the changes of U speciation along the salinity gradient. The speciation modelling of U showed that calcium uranyl carbonate complexes dominate along the Scheldt estuary (from 97 to 86% seawards) with increasing fraction of UO 2 (CO 3) 3 4− (from 2 to 14%) towards the mouth. [Display omitted] • Comparative study of DGT resins for determination of uranium reveals their applicability in natural waters. • The Chelex-100 and Lewatit FO 36 are not suitable for application in seawater (salinity >5 and 18, respectively). • Dow-PIWBA and Diphonix provide excellent results in seawater (salinity ∼27). • Only Diphonix quantitatively accumulates uranium even after 28 days of deployment in seawater. • Uranium speciation along the salinity gradient has strong influence on the DGT performance. [ABSTRACT FROM AUTHOR]

Abstract: High resolution profiles of trace elements (Fe, Mn, Co, As, Cu, Cr, Ni and Pb) were assessed using the DET (Diffusive Equilibrium in Thin films) and DGT (Diffusive Gradients in Thin films) techniques in silty, organically enriched, sub-tidal sediments of the Belgian coast during late winter and spring 2008. The general chemical properties of the sediments such as dissolved oxygen, pH, Eh and sulfide profiles, controlling precipitation/mobilization reactions, were determined with electrodes (pH and Eh) and microelectrodes (oxygen) and AgI-DGT probes (sulfide). Most trace elements show subsurface maxima and low concentrations beneath 8 cm of depth. The main physicochemical parameters controlling the vertical concentration profiles are dissolved oxygen and redox potential in the surface sediment and sulfide in the deeper sediment layers. Thermodynamic equilibrium calculations have been carried out verifying which solid phases can explain the dissolved trace metal concentrations. Seasonal variations of trace elements have been observed during the sampling period and sedimentation of fresh particulate organic matter (POM) derived from phytoplankton blooms appear to be the main cause of this temporal variability. Flux calculations based on DGT profiles (these fluxes are minimum ones) show that exchange fluxes of trace metals in February are slightly higher than in April. In addition, “DGT pistons” were deployed at the sediment water interface (SWI) to accumulate labile ions from below. This way all labile ions, binding onto the DGT Chelex resin, are pumped out of the pore waters and the solid sediment phase (only the mobile fraction). These results are a direct estimation of the amount of trace elements that can be released from the upper sediment to the water column (in the range of 4.4·10−5 to 0.10 mmol·m−2·d−1 for Co, Pb, Cr, As, Cu, Ni, Fe and Mn). [Copyright &y& Elsevier]

The distribution and geochemistry of arsenic (As) in water and sediments of the Zenne River, a small urban river flowing through Brussels (Belgium), were assessed based on the results of 18 sampling campaigns performed between 2010 and 2021. In general, concentrations of As sharply increase between Vilvoorde and Eppegem and are up to 6-8 times higher in the section downstream of Eppegem in comparison to the upstream part of the Zenne. The monitoring surveys in which the grab water samples were taken at a 1-hour sampling frequency revealed that the large temporal variability in As concentrations found in the downstream part of the river is driven by the tidal cycle. The diffusive gradients in thin films (DGT) technique was used to assess the DGT labile As species in surface water and sediment porewater. Three DGT sorbents (Metsorb, Lewatit FO 36, and ZrO 2 ) for the determination of total As were applied to compare their performance, and the 3-mercaptopropyl-functionalized silica (3-MFS) was used for the speciation of As(III) in porewater. Arsenic species are fully labile in surface waters as the DGT time-integrated concentrations of As were in good agreement with the average concentrations calculated from the grab samplings. In sediment porewaters, As is predominantly present as non-DGT labile species (66-93 %), and the DGT labile As fraction is dominated by As(III). Flux calculations evaluating the relative importance of different As sources to the Zenne River revealed the presence of a point source on the tributary Tangebeek, which contributes to 87 % of the As load carried by the Zenne River., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The Flemish Centre for Environment and Health started with human biomonitoring in 2002 (FLEHS I: 2002-2006). The main goal of the second human biomonitoring cycle (FLEHS II: 2007-2011), was to determine mean values for a large number of pollutants in a representative sample of the general Flemish population. Values for Cd and Pb were updated, and a group of previously undetermined metals and metalloids (As, Mn, Cu and Tl) were included in some of the age groups. In this human biomonitoring program, three different age groups of the general Flemish population were monitored: 255 newborns and their mothers, 210 adolescents aged 14-15, and 204 adults between 20 and 40 years old. Trace elements were determined in cord blood and maternal blood of the mothers, in blood and urine of adolescents and in urine of adults. Determinants of life-style and personal factors were taken into account. The levels of trace elements in cord blood and maternal blood were for most elements at the lower end of the range found in literature. For Pb, As and Tl, a strong correlation (respectively r=0.43, 0.55 and 0.33; p<0.05) was found between levels in cord blood (respectively 8.6, 0.54 and 0.017 μg/L) and maternal blood (11.1, 0.64 and 0.028 μg/L), indicating that they are transported via the placenta from mother to fetus. The levels found in the adolescents and adults were compared with results from international biomonitoring studies, and were found to be in the same ranges. With the exception of Pb, all trace elements increased with increasing age group population. Finally, the results also showed that the levels of Cd and Pb in blood for this campaign (e.g. for Pb 8.6 and 14.8 μg/L in neonates and adolescents respectively) were lower compared to the first campaign (e.g. for Pb 14.7 and 21.7 μg/L in neonates and adolescents respectively), indicating a decrease over time. However, differences in sampling strategies might partially explain this observed trend., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

In the Flemish human biomonitoring programme FLEHS II (2007-2011) trace metals (Cd, Pb, Cr, Ni, Cu, Mn, Tl, Sb, As and toxic relevant arsenic) were analysed in the blood and urine of adolescents (14-15 years old) in the reference population in Flanders and in areas of important industrial activities: Genk-Zuid and Menen. After adjustment of the results for confounding factors, the adolescents living in Genk-Zuid had higher levels of Cr, Cu and Tl in blood, higher levels of Cd and toxic relevant arsenic (TRA) in urine, but lower levels of Ni in blood and Sb in urine compared to the reference population. In Menen higher levels of Cd and Cu in urine, higher concentrations of Tl in blood but lower concentrations of Pb in blood and lower Ni, Sb and As in urine were found compared to the reference population. For both the reference population and the hot spots the concentrations are within the ranges found in other countries. Compared to the previous biomonitoring programme FLEHS I (2002-2006) a decrease in the concentrations of Cd and especially of Pb in blood was observed. However, it cannot be excluded that differences between the two campaigns are partially due to different sampling strategies., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Predicting metal concentrations in surface waters is an important step in the understanding and ultimately the assessment of the ecological risk associated with metal contamination. In terms of risk an essential piece of information is the accurate knowledge of the partitioning of the metals between the dissolved and particulate phases, as the former species are generally regarded as the most bioavailable and thus harmful form. As a first step towards the understanding and prediction of metal speciation in the Scheldt Estuary (Belgium, the Netherlands), we carried out a detailed analysis of a historical dataset covering the period 1982-2011. This study reports on the results for two selected metals: Cu and Cd. Data analysis revealed that both the total metal concentration and the metal partitioning coefficient (Kd) could be predicted using relatively simple empirical functions of environmental variables such as salinity and suspended particulate matter concentration (SPM). The validity of these functions has been assessed by their application to salinity and SPM fields simulated by the hydro-environmental model SLIM. The high-resolution total and dissolved metal concentrations reconstructed using this approach, compared surprisingly well with an independent set of validation measurements. These first results from the combined mechanistic-empirical model approach suggest that it may be an interesting tool for risk assessment studies, e.g. to help identify conditions associated with elevated (dissolved) metal concentrations., (Copyright © 2013 Elsevier B.V. All rights reserved.)