Effects and bioaccumulation of Cr(III), Cr(VI) and their mixture in the freshwater mussel Corbicula fluminea.

Chromium has two main oxidation states, Cr(III) and Cr(VI), that can occur simultaneously in natural waters. Current consensus holds that Cr(VI) is of high ecotoxicological concern, but regards Cr(III) as poorly bioavailable and relatively non-toxic. In this work, the effects and bioaccumulation of Cr(III), Cr(VI) and their mixture were studied using the freshwater clam Corbicula fluminea as a model organism.

Contrasting distribution of REE and yttrium among particulate, colloidal and dissolved fractions during low and high flows in peri-urban and agricultural river systems.

Understanding the possible consequences of anthropogenic activities on REY environmental fate and adverse effects on biota requires a detailed knowledge of their distribution between the particulate, colloidal and dissolved fractions. Such information is practically non-existent for peri-urban rivers having heavily populated basins and suffering from direct impacts from various human activities. The present study compared the distribution of REY among the particulate (>1000 nm), coarse colloidal (1000 nm - 220 nm), small colloidal (220 nm - 10 kDa) and dissolved (<10 kDa) water fractions in two peri-urban river basins having contrasted land uses (agricultural vs urban/industrial) under low and high flow conditions.

Effect of lockdown on wastewater characteristics: a comparison of two large urban areas.

The effect of the lockdown imposed to limit the spread of SARS-CoV-2 in France between March 14 and May 11, 2020 on the wastewater characteristics of two large urban areas (with between 250,000 and 300,000 inhabitants) was studied. The number of outward and inward daily commuters was extracted from national census databases related to the population and their commuting habits. For urban area A, with the larger number of daily inward commuters (110,000, compared to 53,000 for B), lockdown was observed to have an effect on the monthly load averages of chemical oxygen demand, biochemical oxygen demand, total Kjeldahl nitrogen, total suspended solids and total phosphorus, all of which decreased (confidence level of 95%).

Understanding Rare Earth Elements concentrations, anomalies and fluxes at the river basin scale: The Moselle River (France) as a case study.

Anthropogenic activities linked to various new technologies are increasingly disrupting REEs biogeochemical cycles. A catchment-based perspective is therefore necessary to distinguish between natural (i.e.

Chromium hazard and risk assessment: New insights from a detailed speciation study in a standard test medium.

Despite the consensus about the importance of chemical speciation in controlling the bioavailability and ecotoxicity of trace elements, detailed speciation studies during laboratory ecotoxicity testing remain scarce, contributing to uncertainty when extrapolating laboratory findings to real field situations in risk assessment. We characterized the speciation and ecotoxicological effects of chromium (Cr and Cr ) in the International Organization for Standardization (ISO) medium for algal ecotoxicity testing. Total and dissolved (< 0.

The European water-based environmental quality standard for pentachlorophenol is NOT protective of benthic organisms.

Risk management of toxic substances is often based on Environmental Quality Standards (EQS) set for the water compartment, assuming they will also protect benthic organisms. In the absence of experimental data, EQS for sediments can be estimated by the equilibrium partitioning approach. The present study investigates whether this approach is protective of benthic organisms against pentachlorophenol (PCP), a legacy contaminant and EU priority substance still used in some parts of the world.

Bioaccumulation and subcellular partitioning of Cr(III) and Cr(VI) in the freshwater green alga Chlamydomonas reinhardtii.

Chromium occurs in aquatic environments under two main redox forms, namely Cr(III) and Cr(VI), with different geochemical and biochemical properties. Cr(VI) readily crosses biological membranes of living organisms and once inside the cells it undergoes a rapid reduction to Cr(III). The route of entry for the latter form is, however, poorly known.

Total and methylmercury partitioning between colloids and true solution: From case studies in sediment overlying and porewaters to a generalized model.

Tangential flow ultrafiltration was used to determine the partitioning of total mercury (THg) and monomethylmercury (MMHg) between colloids and true solution in sediment overlying and porewaters collected in Lake Geneva (Switzerland and France), Venice Lagoon (Italy), and Baihua Reservoir (China). Overlying water and porewater spanned different ranges of THg and MMHg concentrations, redox conditions, and salinity. Total Hg, MMHg, and dissolved organic carbon (DOC) concentrations were measured in filter-passing (<0.

Lanthanide ecotoxicity: first attempt to measure environmental risk for aquatic organisms.

The geochemical cycles of lanthanides are being disrupted by increasing global production and human use, but their ecotoxicity is not fully characterized. In this study, the sensitivity of Aliivibrio fischeri and Pseudokirchneriella subcapitata to lanthanides increased with atomic number, while Daphnia magna, Heterocypris incongruens, Brachionus calyciflorus and Hydra attenuata were equally sensitive to the tested elements. In some cases, a marked decrease in exposure concentrations was observed over test duration and duly considered in calculating effect concentrations and predicted no effect concentrations (PNEC) for hazard and risk assessment.

Environmental fate and ecotoxicity of lanthanides: are they a uniform group beyond chemistry?

Lanthanides are a chemically uniform group of metals (La-Lu) that, together with yttrium (Y) and scandium (Sc), form the group of rare earth elements (REEs). Because of their many applications (e.g.

How reliable are data for the ecotoxicity of trivalent chromium to Daphnia magna?

Risk assessments from the European Union and the World Health Organization report values for acute and chronic toxicity of Cr(III) to Daphnia magna in the range of 0.6 mg/L to 111 mg/L and 0.047 mg/L to 3.

Bioaccumulation kinetics and effects of sediment-bound contaminants on chironomids in deep waters: new insights using a low-disturbance in situ system.

Effective assessment of sediment quality and associated risks requires further integration between laboratory-based studies and field observations. Tools for in situ exposure of laboratory-reared organisms are particularly suitable for this purpose. However, available tools suffer from technical drawbacks that limit their use in deep waters and their general ability to provide results linking laboratory and field observations.

Trace element contamination in the arms of the Danube Delta (Romania/Ukraine): current state of knowledge and future needs.

This paper provides the first critical synopsis of contamination by selected trace elements in the whole Danube Delta (Romania/Ukraine) to: identify general patterns of contamination by trace elements across the Delta, provide recommendations to refine existing monitoring networks and discuss the potential toxicity of trace elements in the whole Delta. Sediment samples were collected between 2004 and 2007 in the three main branches of the Delta (Chilia, Sulina and Sfantu Gheorghe) and in the secondary delta of the Chilia branch. Samples were analyzed for trace elements (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) and TiO₂, Fe₂O₃, MnO, CaCO₃ and total organic carbon.

Public health benefits and risks of fish consumption: current scientific evidence v. media coverage.

Objective: To evaluate if and how the current degree of scientific uncertainty about the safety of fish consumption is incorporated at the media level.

Design: We used a dedicated software (TalTac®) to investigate the content of 169 news articles related to ‘mercury and fish consumption’ that appeared from 1990 to 2010 in the two Italian broadsheets with the highest circulation figures, in order to identify journalistic frames used in the coverage of benefits v. risks associated with fish consumption.

Characterization of trace element geochemistry in continuous flow-through microcosms: a preliminary step to environmentally meaningful ecotoxicological experiments.

The increasing use of freshwater/sediment microcosms in geochemical and ecotoxicological studies requires additional efforts to characterize and understand their functioning and the main parameters that can influence the pollutants' behavior and bioavailability inside the microcosms themselves. In this study, we investigated the geochemical behavior of four elements (Cr(III), Cu, Cd, and Pb) in microcosms containing one type of natural water and sediment. The microcosms were operated under flow-through conditions with continuous metal spiking (2.

Chromium(VI) is more toxic than chromium(III) to freshwater algae: a paradigm to revise?

The behavior and toxicity of Cr(III) and Cr(VI) to the green algae Pseudokirchneriella subcapitata and Chlorella kessleri were studied in a standard culture medium (ISO medium) and, for P. subcapitata only, in ultrafiltered natural water enriched with all ISO components (modified ISO medium). In all solutions amended with Cr(III), initial chromium concentrations decreased by 60-90% over 72h (the duration of algal tests) indicating that protocols for testing poorly soluble substances are required to properly evaluate Cr(III) toxicity.

Sediment quality assessment in the Gulf of Gdańsk (Baltic Sea) using complementary lines of evidence.

Sediments from Polish coastal environments were classified by a quality assessment approach that took into account trace metal and organic micropollutant concentrations, grain-size distribution, and organic carbon content. Generally, no benthic organisms were found at sites where sediments were classified as heavily polluted. However, areas characterized by a moderate contamination showed a variable composition of the benthic community and changing bioaccumulation patterns; therefore, no single species found in the Gulf of Gdańsk could be considered representative of the whole benthic environment.

Chromium speciation study in polluted waters using catalytic adsorptive stripping voltammetry and tangential flow filtration.

The catalytic adsorptive stripping voltammetry (CAdSV) has been applied to physico-chemical chromium speciation study in the upper Dunajec catchment, severely polluted by the tannery wastewater. The method is based on the adsorptive preconcentration of the Cr(III)-diethylenetriammine-N,N,N',N'',N''-pentaacetic acid (DTPA) complex and the utilization of the catalytic reaction in the presence of nitrate. Under optimized conditions the CAdSV enables the oxidation state speciation study of Cr content by direct determination of Cr(VI) in the presence of the predominant Cr(III) concentration with the detection limit for chromium(VI) of 0.

Temporal decrease of trivalent chromium concentration in a standardized algal culture medium: experimental results and implications for toxicity evaluation.

The fate of two trivalent chromium salts (nitrate and chloride) in ISO algal culture medium was followed over 72 h; i.e., the typical duration of algal toxicity tests.

Variability of the colloidal molybdate reactive phosphorous concentrations in freshwaters.

Colloidal-size particles play an important, yet not very well understood, role in the speciation of phosphate in freshwaters. This study assesses the size distribution of molybdate reactive phosphorous in various 1.2 microm-filtered freshwaters using cross-flow filtration.