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•First Gd flux model based on the consumption of gadolinium-based contrast agents.•Anthropogenic Gd flux model extrapolated to 48 European countries.•Major contribution of Germany, ...France and Italy with 40 % of European fluxes.•Influence of the COVID-19 health crisis on European Gd fluxes.•Relevant model for health risk assessment and environmental protection worldwide.
Marine ecosystems are exposed to a multitude of stresses, including emerging metals as Rare Earth Elements. The management of these emerging contaminants represents a significant environmental issue. For the past three decades, the increasing medical use of gadolinium-based contrast agents (GBCAs) has contributed to their widespread dispersion in hydrosystems, raising concerns for ocean conservation. In order to control GBCA contamination pathways, a better understanding of the cycle of these elements is needed, based on the reliable characterization of fluxes from watersheds.
Our study proposes an unprecedented annual flux model for anthropogenic gadolinium (Gdanth) based on GBCA consumption, demographics and medical uses. This model enabled the mapping of Gdanth fluxes for 48 European countries. The results show that 43 % of Gdanth is exported to the Atlantic Ocean, 24 % to the Black Sea, 23 % to the Mediterranean Sea and 9 % to the Baltic Sea. Together, Germany, France and Italy contribute 40 % of Europe’s annual flux. Our study was therefore able to identify the current and future major contributors to Gdanth flux in Europe and identify abrupt changes related to the COVID-19 pandemic.
Contrasting seasonal variations occur in river flow and water quality as a result of short duration, severe intensity storms and typhoons in Taiwan. Sudden changes in river flow caused by impending ...extreme events may impose serious degradation on river water quality and fateful impacts on ecosystems. Water quality is measured in a monthly/quarterly scale, and therefore an estimation of water quality in a daily scale would be of good help for timely river pollution management. This study proposes a systematic analysis scheme (SAS) to assess the spatio-temporal interrelation of water quality in an urban river and construct water quality estimation models using two static and one dynamic artificial neural networks (ANNs) coupled with the Gamma test (GT) based on water quality, hydrological and economic data. The Dahan River basin in Taiwan is the study area. Ammonia nitrogen (NH3–N) is considered as the representative parameter, a correlative indicator in judging the contamination level over the study. Key factors the most closely related to the representative parameter (NH3–N) are extracted by the Gamma test for modeling NH3–N concentration, and as a result, four hydrological factors (discharge, days w/o discharge, water temperature and rainfall) are identified as model inputs. The modeling results demonstrate that the nonlinear autoregressive with exogenous input (NARX) network furnished with recurrent connections can accurately estimate NH3–N concentration with a very high coefficient of efficiency value (0.926) and a low RMSE value (0.386 mg/l). Besides, the NARX network can suitably catch peak values that mainly occur in dry periods (September–April in the study area), which is particularly important to water pollution treatment. The proposed SAS suggests a promising approach to reliably modeling the spatio-temporal NH3–N concentration based solely on hydrological data, without using water quality sampling data. It is worth noticing that such estimation can be made in a much shorter time interval of interest (span from a monthly scale to a daily scale) because hydrological data are long-term collected in a daily scale. The proposed SAS favorably makes NH3–N concentration estimation much easier (with only hydrological field sampling) and more efficient (in shorter time intervals), which can substantially help river managers interpret and estimate water quality responses to natural and/or manmade pollution in a more effective and timely way for river pollution management.
•A systematic analysis scheme (SAS) is proposed in response to river water pollution.•For tackling data scarcity problems, Gamma test and cross-validation are implemented.•One dynamic and two statics neural networks are used to model NH3–N concentration.•NARX can well track the dynamic feature of NH3–N time series and capture its pattern.•SAS favorably makes the estimation of NH3–N concentration easier and more efficient.
•Joint analysis of dated cores and subsurface sediments to reconstruct pollution trends.•Local geochemical backgrounds established from pre-industrial palaeochannel cores.•Metal trajectories ...influenced by local hotspots and diffuse pollution until the 1990s.•Sediment quality recovery varied from a metal to another and according to the location.•High influence of some metals (e.g. Cu) in the risk of pollutant mixture.
In European rivers, research and monitoring programmes have targeted metal pollution from bed and floodplain sediments since the mid-20th century by using various sampling and analysis protocols. We propose to characterise metal contamination trajectories since the 1960s based on the joint use of a large amount of data from dated cores and subsurface sediments along the Rhône River (ca. 512 km, Switzerland–France). For the reconstruction of spatio-temporal trends, enrichment factors (EF) and geo-accumulation (Igeo) approaches were compared. The latter index was preferred due to the recurrent lack of grain-size and lithogenic elements in the dataset. Local geochemical backgrounds were established near (1) the Subalps and (2) the Massif Central to consider the geological variability of the watershed. A high contamination (Igeo = 3–5) was found for Cd, Cu and Zn from upstream to downstream over the period 1980–2000. This pattern is consistent with long-term emissions from major cities and the nearby industrial areas of the Upper Rhône (Geneva, Arve Valley), and Middle Rhône (Lyon, Chemical Corridor, Gier Valley). Hotspots due to Cu and Zn leaching from vineyards, mining, and highway runoff were also identified, while Pb was especially driven by industrial sources. The recovery time of pollution in sediment varied according to the metals and was shorter upstream of Lyon (15–20 years) than downstream (30–40 years). More widely, it was faster on the Rhône than along other European rivers (e.g. Seine and Rhine). Finally, the ecotoxicological mixture risk of metal with Persistent Organic Pollutants (POPs) for sediment-dwelling organisms showed a medium “cocktail risk” dominated by metals upstream of Lyon, although it is enhanced due to POPs downstream, and southward to the delta and the Mediterranean Sea. Overall, this study demonstrates the heterogeneity of the contamination trends along large fluvial corridors such as the Rhône River.
High temporal resolution sampling of runoff (15 samples/4 h) and river water (24 samples/24 h) was performed during a major rainstorm (41 mm/4 h) in the Bordeaux Metropole, after a dry and high ...vehicle-density period. Runoff was sampled at the outlet of one collector draining Northern Bordeaux Highway (NBH; 80,000–93,000 vehicles/day) and river water in the downstream Jalle River. The studied metals, including priority and emergent (Rare Earth Elements REEs) contaminants, showed major temporal and spatial variations in the dissolved and particulate concentrations. Hierarchical cluster analyses distinguished metal groups, reflecting different: (i) sources (i.e., automotive traffic: Zn–Cu–Ce and wastewater treatment plant: Cd–Ag–Gd) and/or (ii) processes (i.e., groundwater dilution by rainwater and sorption processes). The contribution of the particulate fraction to total metal fluxes was predominant in the NBH collector (except for Sr and Mo) and highly variable in the Jalle River, where the highest particulate metal loads were due to the export of road dusts exported by the NBH collector. Metal fluxes from the NBH collector represented highly variable fractions of daily fluxes into the Gironde Estuary at the outlet of the Jalle River, depending on elements and partitioning. The resulting relative contributions ranged from: 5% (Sr) to 40% (Cu) for dissolved phases and 30% (As) to 88% (Cu) for particulate phases. The first 40 min of the event accounted for 65% of the suspended particulate matter flux (and associated particulate metals) exported by the NBH collector, whereas the respective water flux contribution was 35%. This finding clearly demonstrates the importance of monitoring the first minutes of rainy events when establishing mass balances in urban systems.
The Congo (Zaire) River, the world's second largest river in terms both of water discharges and of drainage area after the Amazon River, has remained to date in a near‐pristine state. For a period ...between 2 and 6 years, the mainstream near the river mouth (Brazzaville/Kinshasa station) and some of the major and minor tributaries (the Oubangui, Mpoko, and Ngoko‐Sangha) were monitored every month for total suspended sediment (TSS), particulate organic carbon (POC), and dissolved organic carbon (DOC). In this large but relatively flat equatorial basin, TSS levels are very low and organic carbon is essentially exported as DOC: from 74% of TOC for the tributaries flowing in savannah regions and 86% for those flowing in the rain forest. The seasonal patterns of TSS, POC, and DOC show clockwise hysteresis in relation to river discharges, with maximum levels recorded 2 to 4 months before peak flows. At the Kinshasa/Brazzaville station, the DOC distribution is largely influenced by the input from the tributaries draining the large marshy forest area located in the center of the basin. There is a marked difference between specific fluxes, threefold higher in the forest basins than in the savannah basins. The computation of inputs to the Atlantic Ocean demonstrates that the Congo is responsible for 14.4 × 106 t/yr of TOC of which 12.4 × 106 t/yr is DOC and 2 × 106 t/yr is POC. The three biggest tropical rivers (the Amazon, the Congo, and the Orinoco), with only 10% of the exoreic world area drained to world oceans, contribute ∼4% of its TSS inputs but 15–18% of its organic carbon inputs. These proportions may double when considering only world rivers discharging into the open ocean.
Abstract 137 Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the early beginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use ...of nuclear energy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed at the scale of French large river basins since 1945, and trajectories in French nuclearized rivers were established using sediment coring. Our results show that 137 Cs contents in sediments of the studied rivers display a large spatial and temporal variability in response to the various anthropogenic pressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected by atmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also received significant fallout from the Chernobyl accident in 1986 and recorded significant 137 Cs concentrations in their sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries. The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, the Seine River display the lowest 137 Cs concentrations regardless of the period. All the rivers responded similarly over time to atmospheric fallout on their catchment, underlying a rather homogeneous resilience capacity of these river systems to this source of contamination.
The increase in human population and urbanization are resulting in an increase in the volume of wastewater and urban runoff effluents entering natural ecosystems. These effluents may contain multiple ...pollutants to which the biological response of aquatic organisms is still poorly understood mainly due to mixture toxicity and interactions with other environmental factors. In this context, RNA sequencing was used to assess the impact of a chronic exposure to wastewater treatment plant and stormwater effluents at the whole-transcriptome level and evaluate the potential physiological outcomes in the Asian clam Corbicula fluminea.
We de-novo assembled a transcriptome from C. fluminea digestive gland and identified a set of 3,181 transcripts with altered abundance in response to water quality. The largest differences in transcriptomic profiles were observed between C. fluminea from the reference site and those exposed to wastewater treatment plant effluents. On both anthropogenically impacted sites, most differentially expressed transcripts were involved in signaling pathways in relation to energy metabolism such as mTOR and FoxO, suggesting an energy/nutrient deficit and hypoxic conditions. These conditions were likely responsible for damages to proteins and transcripts in response to wastewater treatment effluents whereas exposure to urban runoff might result in immune and endocrine disruptions.
In absence of comprehensive chemical characterization, the RNAseq approach could provide information regarding the mode of action of pollutants and then be useful for the identification of which parameters must be studied at higher integration level in order to diagnose sites where the presence of complex and variable mixtures of chemicals is suspected.
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•Clams were caged for 3 months in a river receiving WWTP and stormwater effluents.•We de-novo assembled a transcriptome from clams’ digestive glands.•3181 genes were differentially expressed between sites.•Water pollution induced disorders to energy metabolism and immunity.•RNAseq allowed the identification of novel early-warning molecular markers.
Platinum (Pt) is a technology critical element (TCE) for which biogeochemical cycles are still poorly understood. This lack of knowledge includes Pt effects on marine organisms, which proved to be ...able to bioconcentrate this trace element. Oysters
Crassostrea gigas
were exposed to stable Pt isotope spiked daily in seawater for 35 days. Seawater was renewed daily and spiked (with Pt(IV)) to three nominal Pt concentrations (50, 100, and 10,000 ng L
−1
) for two replicate series. Organotropism study revealed that gills, and to a lesser extent mantle, are the key organs regarding Pt accumulation, although a time- and concentration-dependent linear increase in Pt levels occurred in all the organs investigated (i.e., digestive gland, gonads, gills, mantle, and muscle). In oysters exposed to Pt concentrations of 10,000 ng L
−1
, significant biomarker impairments occurred, especially at cellular levels. They reflect altered lipofuscin and neutral lipid contents, as well as intralysosomal metal accumulation. These observations were attributed to activation of excretion/detoxification mechanisms, including Pt elimination through feces and clearly support the importance of the digestive gland in the response to direct Pt exposure. Despite relatively constant condition index, the integrative biological response (IBR) index suggests a generally decreasing health status of oysters.
High precision MC-ICP-MS Cu isotope measurements were performed on suspended particulate matter (SPM) and filtered water sampled along the turbidity gradient of the fluvial Gironde Estuary (Garonne ...Branch), following a summer lasting period of low freshwater discharge. High Cu concentrations (up to ~200μg/g) in particulate organic carbon (POC)-rich (up to ~14%) particles upstream from the Maximum Turbidity Zone (MTZ) coincide with the most negative δ65Cu values (down to −0.39‰). This suggests the preferential uptake of light Cu isotopes by phytoplankton or anthropogenic contamination from CuSO4 fungicides related to intensive wine farming in the area (δ65Cu=−0.37‰ for vineyard soils). Suspended particulate matter samples in the MTZ exhibit lower Cu concentrations (~35μg/g) and heavier isotopic compositions (δ65Cu=−0.20‰ in average), as recorded by other samples from the Gironde Watershed. Along the fluvial estuary, dissolved Cu is mostly enriched in heavy isotopes (up to δ65Cu=+0.21‰), but negative signatures down to δ65Cu=−0.66‰ occur near the city of Bordeaux. Release of dissolved Cu was attributed to the mineralization of organic matter with a total addition of ~600ng/L in the fluvial estuary. Continuously decreasing amounts of dissolved Cu added with distance suggest that the observed Cu release evolved towards completion in the MTZ and contributed to negative values for dissolved Cu isotopes, as modeled by a Rayleigh process. Urban wastewater effluents probably also contribute to both (i) the dissolved Cu addition (10–20%) in the MTZ and (ii) negative Cu isotope signatures. Further work is necessary to assess the respective roles of anthropogenic sources and biogeochemical fractionation processes. Accordingly, the present study provides new insights into the potential of Cu isotopes for fingerprinting sources and mechanisms involved in the biogeochemical cycle of Cu in temperate aquatic environments impacted by anthropogenic activities.
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•Copper enrichments in particles are related to primary production or anthropogenic contamination.•Organic matter mineralization is accompanied by an addition of dissolved Cu.•Phytoplankton may assimilate preferentially light copper isotopes.•Dissolved Cu is enriched in heavy Cu isotopes.•Anthropogenic sources are enriched in light Cu isotopes.
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