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In densely populated urban areas, the pressure on water resources is considerable and will tend to intensify over the next decades. Preserving water resources therefore seems fundamental, but many questions remain as to the transfer of contaminants to subsurface waters in these largely sealed areas. Because of their toxicity and persistence in the environment, this work focused on the study of polycyclic aromatic hydrocarbons (PAHs), ubiquitous pollutants mainly produced by human activities. To better understand the main factors leading to the retention or transport of these pollutants in urban environments, vertical transects, from the surface to several meters down, were established on three study sites in or near Paris (France), selected according to an urbanization gradient. Soil samples collected at the surface and urban secondary carbonate deposits (USCD), similar to cave speleothems, sampled underground in quarries and aqueducts were analyzed. As the hydrophobic properties of PAHs favor their sorption onto organic matter, the latter was also studied using organic carbon analysis and UV fluorescence spectroscopy. The USCD located closest to the urbanized surface contained high concentrations of PAHs (76.8 ± 5.3 ng g -1 ), while the USCD located at greater depth with organic soil on the surface contained the lowest amount of PAHs (2.9 ± 0.4 ng g -1 ), and no PAHs with log K OC > 5. The results highlight the predominant role played by the presence of organic topsoil at the surface in retaining and storing large amounts of PAHs (1914-2595 ng. g soil -1 ), particularly the most hydrophobic ones (i.e. 60% of the 15 PAHs are characterized by a Log K OC >5), which are also the most toxic. The lithology and thickness of the bedrock (between the surface and the USCD) also play an important role in the retention of PAHs, particularly those adsorbed on the particulate phase., 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 © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Metal-rich fumes emitted during ore smelting contribute to widespread anthropogenic contamination. Environmental archives (such as lake sediments) record fallouts deposited on lake and terrestrial surfaces during ancient mining and smelting activities. However, very few is known about the potential buffering effect of soils upon which metal falls out, prior to be released through runoff and or/erosion, hence leading to pervasive contamination fluxes long after the ceasing of metallurgical activities. Here we aim at assessing this long-term remobilisation in a mountainous catchment area. Lake sediments and soils were collected 7 km upward a 200-year-old historic mine. The PbAg mine of Peisey-Nancroix was operated between the 17th and the 19th centuries with a documented smelting period of 80 years. In lake sediments, the total Pb content varies from 29 mg.kg -1 prior smelting to 148 mg.kg -1 during ore smelting. Pb isotopes in lake sediments and soils provide evidence of anthropogenic Pb from the local ore ( 206 Pb/ 207 Pb = 1.173; 208 Pb/ 206 Pb = 2.094) during and after smelting, suggesting anthropogenic Pb remobilisation for 200 years. The accumulation rates of anthropogenic Pb calculated in lake sediments after the smelting period confirm such a remobilisation. Despite a decrease in this accumulation rate through time, soils still contain significant stocks of anthropogenic Pb (54-89 % of Pb ANTH ). The distribution of present-day anthropogenic Pb in the catchment area depends mainly on topographic characteristics. Coupling lake sediments and soils investigations is thus necessary to constrain the long-term persistence and remobilisation of a diffuse contamination related to mining activities., 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 © 2023 Elsevier B.V. All rights reserved.)

The present study investigated metal and metalloid dynamics in the estuarine water of the Doce River (Brazil) after the collapse of an iron ore-processing tailing dam in 2015. Spectroscopic and isotopic techniques were applied to bring new insights into the effects of the dam failure on the dynamics and hazardousness of particulate and dissolved metal(loid) concentrations along the fluvial-estuarine continuum. Spectroscopic analysis showed that the suspended particulate matter (SPM) of the Doce River estuary consisted of a combination of soil-delivered particles and fine tailing mud particles with small amounts of coarse tailing mud Fe oxides (~150-μm width). Enrichment and contamination factors showed that the dam failure increased particulate Fe, Pb, Cd, and As, and dissolved Pb concentrations. Total concentrations of As (15 μg/L), Pb (30 μg/L), Cd (8 μg/L), and Cr (105 μg/L) increased up to values higher than quality and regulatory guidelines. Human health risk assessment showed that local communities are exposed to a potentially chronic Cr noncarcinogenic effects, although Cr high concentrations were not linked with the dam failure by this study. The particulate Pb isotope signatures reported herein ( 206/207 Pb ratios of 1.214 ± 0.006 and 208/206 Pb ratios of 2.025 ± 0.011) can be applied to constrain metal(loid) sources in the Doce River sediment plume and continental shelf. The river-ocean mixing zone caused abrupt changes metal(loid) partitioning (Zn, Pb, Cr, Cu, Cd, and As), controlling their fate in the estuary and the Brazilian southeast coastal., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Stable carbon isotope ratios have many applications in natural sciences. In the first worldwide interlaboratory proficiency test, the discrepancies in measured δ 13 C DIC values of natural waters were up to σ = ±3‰. Therefore, we continued the investigation on the analytical data quality assurance of individual laboratories and internal consistency among laboratories worldwide., Methods: We designed and performed an interlaboratory comparison exercise for δ 13 C analyses of ten water and two solid samples (Na 2 CO 3 , CaCO 3 ), including two synthetic samples prepared by dissolving the carbonates individually. Three laboratories analyzed an additional sample set to assess solution stability, at least one month after the first set analysis period. The δ 13 C values were measured using dual inlet isotope ratio mass spectrometry (DI-IRMS) or continuous flow (CF)-IRMS., Results: The δ 13 C values of solid Na 2 CO 3 and its aqueous solution were -5.06 ± 0.21‰ and 5.32 ± 0.24‰, respectively, while the δ 13 C value of solid CaCO 3 was -4.49 ± 0.93‰. Similarly, the lake water has a consistent value (2.45 ± 0.19‰). The δ 13 C values of geothermal water have a wide dispersion among individual laboratory measurements and among those of different laboratories; however, a trend exists in the δ 13 C values measured at the three sampling points of each well., Conclusions: The δ 13 C values of solid Na 2 CO 3 and its solution, and lake water (i.e. DIC concentration samples >100 mg/L carbon) are consistent among all the participating laboratories. The dispersion in the δ 13 C values of solid CaCO 3 is associated with its lower chemical affinity than that of Na 2 CO 3 . The poor reproducibility in the δ 13 C values of geothermal fluids, collected at three points of a geothermal well, despite overall consistent trends regarding their collection points suggests inadequate sample handling (atmospheric CO 2 exchange) and/or inappropriate analytical approaches (incomplete H 3 PO 4 acid reaction)., (© 2019 John Wiley & Sons, Ltd.)

Polycyclic aromatic hydrocarbons (PAH) have been released by human activities during more than a century, contaminating the entire atmosphere - soil - river continuum. Due to their ubiquity in the environment and their potential severe biological impacts, PAH became priority pollutants and were targeted by environmental public agencies. To better manage PAH pollution, it is necessary to identify unambiguously the sources and pathways of those compounds at the catchment scale, and to evaluate the persistence of historical PAH pollution in the environment especially in those urban contexts concentrating multiple PAH sources. Accordingly, the current research monitored the contamination in atmospheric fallout, soils and rivers of a 950-km 2 catchment (Orge River) characterized by an increasing urban gradient in downstream direction, and located in the Seine River basin characterized by a high level of PAH legacy contamination. A combination of various approaches was used, including the widely used PAH diagnostic ratios, together with innovative methods such as PAH correlations and sediment fingerprinting using fallout radionuclides to clearly identify both the origin of PAH and their main PAH pathways to the river. The results demonstrated the persistence of legacy PAH contamination in the catchment, responsible for the signature of the suspended particulate matter currently transiting in the Orge River. They underlined the conservation of PAH through the soil - river continuum. Finally, urban runoff was demonstrated to provide the main PAH source to the river in the densely urbanized area by both PAH correlations and sediment fingerprinting. These results were used to model PAH concentrations in those particles supplied from urban areas to the river., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) produced by numerous anthropogenic activities are ubiquitous in the environment and have become a priority concern due to their potential severe biological impacts. A better understanding of PAH transfer at the catchment scale is therefore necessary to improve the management of PAH contaminants and protect rivers. Furthermore, the impact of changes in hydrological regimes and land uses on PAH fluxes should be specifically investigated. Accordingly, the current research monitors the contamination in atmospheric fallout, soils and rivers in a 950-km 2 catchment (Orge River) characterized by an increasing urban gradient in downstream direction. During an entire hydrological year, river water contamination was quantified through regular sampling of both particulate and dissolved material at four river-monitoring stations, reflecting the increasing urbanization gradient. The significant input of PAHs from urban areas in downstream river sections corresponded to a specific PAH flux that reached 23 g km -2 y -1 despite the low sediment yield. Moreover, the comparison with runoff-specific fluxes reported in the literature underlined the major impact of urban runoff on the Orge River water and sediment quality. Nevertheless, the annual PAH load exported by the river (21 kg y -1 ) remained lower than the PAH inputs from atmospheric fallout (173 kg y -1 ), demonstrating the continuous accumulation of PAH from atmospheric fallout in the catchment soils. Consequently, the notably large PAH stock (close to 1000 tons) resulting from historical contamination of this early-industrialized region continues to increase due to ongoing atmospheric inputs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Rationale: Knowledge of the accuracy and precision for oxygen (δ 18 O values) and hydrogen (δ 2 H values) stable isotope analyses of geothermal fluid samples is important to understand geothermal reservoir processes, such as partial boiling-condensation and encroachment of cold and reinjected waters. The challenging aspects of the analytical techniques for this specific matrix include memory effects and higher scatter of delta values with increasing total dissolved solids (TDS) concentrations, deterioration of Pt-catalysts by dissolved/gaseous H 2 S for hydrogen isotope equilibration measurements and isotope salt effects that offset isotope ratios determined by gas equilibration techniques., Methods: An inter-laboratory comparison exercise for the determination of the δ 18 O and δ 2 H values of nine geothermal fluid samples was conducted among eleven laboratories from eight countries (CeMIEGeo2017). The delta values were measured by dual inlet isotope ratio mass spectrometry (DI-IRMS), continuous flow IRMS (CF-IRMS) and/or laser absorption spectroscopy (LAS). Moreover, five of these laboratories analyzed an additional sample set at least one month after the analysis period of the first set. Statistical evaluation of all the results was performed to obtain the expected isotope ratios of each sample, which were then subsequently used in deep reservoir fluid composition calculations., Results: The overall analytical precisions of the measurements were ± 0.2‰ for δ 18 O values and ± 2.0‰ for δ 2 H values within the 95% confidence interval., Conclusions: The measured and calculated δ 18 O and δ 2 H values of water sampled at the weir box, separator and wellhead of geothermal wells suggest the existence of hydrogen and oxygen isotope-exchange equilibrium between the liquid and vapor phases at all sampling points in the well. Thus, both procedures for calculating the isotopic compositions of the deep geothermal reservoir fluid - using either the analytical data of the liquid phase at the weir box together with those of vapor at the separator or the analytical data of liquid and vapor phases at the separator -are equally valid., (© 2018 John Wiley & Sons, Ltd.)

The excessive supply of contaminants from urban areas to rivers during the last centuries has led to deleterious impacts on aquatic ecosystems. The sources, the behavior, and the dynamics of these contaminants must be better understood in order to reduce this excessive anthropogenic pollution. Accordingly, the current research investigated the particle-bound trace element (TE) contamination of the 900-km 2 Orge River (Seine basin, France) and the potential sources of these particles (agricultural or forest soils, channel banks, road deposited sediments), through the analysis of multiple fallout radionuclides, elemental geochemistry, and lead isotopic composition on suspended particulate matter (SPM) collected during a hydrological year at four stations following an increasing urbanization gradient (300 to 5000 inhab.km -2 ). Fallout radionuclide measurements showed an increasing contribution of recently eroded particles from urban areas to the SPM in downstream direction. However, this contribution varied depending on hydrological conditions. A greater contribution of particles originating from urban areas was observed during low stage periods. On the contrary, the contribution of agricultural soils and channel banks that are less enriched in contaminants and fallout radionuclides was higher during seasonal floods, which explained the dilution of radionuclide contents in sediment transiting the river during those events. Trace element contamination of SPM in Cu, Zn, Pb, and Sb increased from moderate to significant levels with urban pressure in downstream direction (with corresponding enrichment factors raising from 2 to 6). In addition, Pb isotopic ratios indicated that the main source of Pb corresponded to the "urban" signature found in road deposited sediments. The low variations in lead isotope ratios found in the SPM for contrasting hydrological conditions demonstrated the occurrence of a single source of Pb contamination. These results demonstrate the need to better manage urban runoff during both flood and low precipitation events to prevent the supply of diffuse particle-bound contamination to rivers draining urban areas.

Tropical rainfall isotopic composition results from complex processes. The climatological and environmental variability in East Africa increases this complexity. Long rainfall isotope datasets are needed to fill the lack of observations in this region. At Kisiba Masoko, Tanzania, rainfall and rain isotopic composition have been monitored during 6 years. Mean year profiles allow to analyse the seasonal variations. The mean annual rainfall is 2099 mm with a rain-weighted mean composition of -3.2 ‰ for δ 18 O and -11.7 ‰ for δ 2 H. The results are consistent with available data although they present their own specificity. Thus, if the local meteoric water line is δ 2 H = 8.6 δ 18 O + 14.8, two seasonal lines are observed. The seasonality of the isotopic composition in rain and deuterium excess has been compared with precipitating air masses backtracking trajectories to characterize a simple scheme of vapour histories. The three major oceanic sources have two moisture signatures with their own trajectory histories: one originated from the tropical Indian Ocean at the beginning of the rainy season and one from the Austral Ocean at its end. The presented isotopic seasonality depends on the balance of the intertropical front and provides a useful dataset to improve the knowledge about local processes.

Rationale: Stable carbon isotope ratios of dissolved inorganic (DIC) and organic carbon (DOC) are of particular interest in aquatic geochemistry. The precision for this type of analysis is typically reported in the range of 0.1‰ to 0.5‰. However, there is no published attempt that compares δ(13)C measurements of DIC and DOC among different laboratories for natural water samples., Methods: Five natural water samples (lake water, seawater, two geothermal waters, and petroleum well water) were analyzed for δ(13)CDIC and δ(13)CDOC values by five laboratories with isotope ratio mass spectrometry (IRMS) in an international proficiency test., Results: The reported δ(13)CDIC values for lake water and seawater showed fairly good agreement within a range of about 1‰, whereas geothermal and petroleum waters were characterized by much larger differences (up to 6.6‰ between laboratories). δ(13)CDOC values were only comparable for seawater and showed differences of 10 to 21‰ for other samples., Conclusions: This study indicates that scatter in δ(13)CDIC isotope data can be in the range of several per mil for samples from extreme environments (geothermal waters) and may not yield reliable information with respect to dissolved carbon (petroleum wells). The analyses of lake water and seawater also revealed a larger than expected difference and researchers from various disciplines should be aware of this. Evaluation of analytical procedures of the participating laboratories indicated that the differences cannot be explained by analytical errors or different data normalization procedures and must be related to specific sample characteristics or secondary effects during sample storage and handling. Our results reveal the need for further research on sources of error and on method standardization., (Copyright © 2013 John Wiley & Sons, Ltd.)

Uremic myopathy seems unfrequently studied although it can be really inconvenient in daily activities for some patients. Its is a proximal and non specific myopathy that should be discriminated from uremic neuropathy. Several disturbances from renal insufficiency have been incriminated but they only play an adjuvant role in regard with renal osteodystrophy. Indeed the presence of myopathy in cases of severe osteodystrophy and its close similarity with myopathies accompanying the different forms of osteomalacia and/or hyperparathyroidism without renal failure suggest that the most important pathogenic factors come from calcium metabolic disorders: excessive parathyroid hormone, vitamin D deficiency, and/or impaired calcium transport. The treatment is subject to the predominant bone lesions: secondary hyperparathyroidism or osteomalacia; but the best attitude remains their prevention.

Uremic myopathy is relatively unknown, despite the fact that it can be quite a severe handicap. It is a non-specific proximal myopathy which must be distinguished from uremic polyneuropathy. Several disorders linked to renal insufficiency have been implicated, but these only play an adjuvant role with regard to renal osteodystrophy. Indeed the presence of myopathy in cases of severe osteodystrophy, its similarity to the myopathies associated with different types of osteomalacia and hyperparathyroidism without renal failure, suggest that the most important pathogenic factor is related to disorders of the calcium phosphate metabolism: excessive parathyroid hormone, vitamin D deficiency and/or impaired calcium transport. Treatment will depend on the predominant bone lesions: secondary hyperparathyroidism or osteomalacia. However prevention remains the best course.