Updated Chronic Copper Bioavailability Models for Invertebrates and Algae.

Chronic copper (Cu) bioavailability models have been successfully implemented in European risk assessment frameworks and compliance evaluations. However, they were developed almost two decades ago, which calls for an update. In the study, we present updated chronic Cu bioavailability models for invertebrates and algae.

Challenges and Recommendations in Assessing Potential Endocrine-Disrupting Properties of Metals in Aquatic Organisms.

New tools and refined frameworks for identifying and regulating endocrine-disrupting chemicals (EDCs) are being developed as our scientific understanding of how they work advances. Although focus has largely been on organic chemicals, the potential for metals to act as EDCs in aquatic systems is receiving increasing attention. Metal interactions with the endocrine system are complicated because some metals are essential to physiological systems, including the endocrine system, and nonessential metals can have similar physiochemical attributes that allow substitution into or interference with these systems.

Following the evidence and using the appropriate regulatory tools: A European-wide risk assessment of copper in freshwaters.

The ecological risks of copper (Cu) in freshwaters have been the focus of regulatory assessments for several decades. Recently, it has been suggested by the European Commission that Cu represents a continent-wide risk to freshwaters. We assessed to what extent this suggestion is supported by the available evidence if Cu bioavailability is considered in the assessment of risk.

Sources of copper into the European aquatic environment.

Chemical contamination from point source discharges in developed (resource-rich) countries has been widely regulated and studied for decades; however, diffuse sources are largely unregulated and widespread. In the European Union (EU), large dischargers report releases of some chemicals, yet little is known of total emissions (point and diffuse) and their relative significance. We estimated copper loadings from all significant sources including industry, sewage treatment plants, surface runoff (from traffic, architecture, and atmospheric deposition), septic tanks, agriculture, mariculture, marine transport (antifoulant leaching), and natural processes.

Adverse Outcome Pathways for Chronic Copper Toxicity to Fish and Amphibians.

In the present review, we synthesize information on the mechanisms of chronic copper (Cu) toxicity using an adverse outcome pathway framework and identify three primary pathways for chronic Cu toxicity: disruption of sodium homeostasis, effects on bioenergetics, and oxidative stress. Unlike acute Cu toxicity, disruption of sodium homeostasis is not a driving mechanism of chronic toxicity, but compensatory responses in this pathway contribute to effects on organism bioenergetics. Effects on bioenergetics clearly contribute to chronic Cu toxicity with impacts at multiple lower levels of biological organization.

Influence of systemic copper toxicity on early development and metamorphosis in Xenopus laevis.

The primary objective of the present study was to examine the influence of early systemic toxicity resulting from copper (Cu) exposure on metamorphic processes in Xenopus laevis. A 28-day exposure study with copper, initiated at developmental stage 10, was performed using test concentrations of 3.0, 9.

Evaluation of effects-based methods as monitoring tools for assessing ecological impacts of metals in aquatic ecosystems.

Effects-based methods (EBMs) are considered part of a more integrative strategy for regulating substances of concern under the European Union Water Framework Directive. In general, EBMs have been demonstrated as useful indicators of effects on biota, although links to population and community-level effects are sometimes uncertain. When EBMs are sufficiently specific and sensitive, and links between measured endpoints and apical or higher level effects are established, they can be a useful tool in assessing effects from a specific toxicant or class of toxicants.

Demonstrating the Reliability of bio-met for Determining Compliance with Environmental Quality Standards for Metals in Europe.

The importance of considering the bioavailability of metals in understanding and assessing their toxicity in freshwaters has been recognized for many years. Currently, biotic ligand models (BLMs) are being applied for the derivation and implementation of environmental quality standards (EQS) for metals under the Water Framework Directive in Europe. bio-met is a simplified tool that was developed for implementing bioavailability-based EQS for metals in European freshwaters.

Copper alloys' metal migration and bioaccessibility in saliva and gastric fluid.

The oral bioaccessibility of copper alloys and pure metals was assessed using in vitro methods with synthetic saliva and gastric fluid. The metal-specific migration rates from polished alloy surfaces are higher in gastric (pH 1.5) than in saliva fluid (pH 7.

Method Development for Determining the Removal of Metals from the Water Column under Transformation/Dissolution Conditions for Chronic Hazard Classification.

An extension of the transformation/dissolution protocol (T/DP) was developed and evaluated as a tool to measure the removal of metals from the water column for chronic aquatic hazard classification. The T/DP extension (T/DP-E) consists of 2 parts: T/DP-E part 1, to measure metal removal from the water column via binding of metals to a substrate and subsequent settling, and T/DP-E part 2, to assess the potential for remobilization of metals following resuspension. The T/DP-E methodology (672-h [28-d] removal period, 1-h resuspension event, and 96-h resettling period) was tested using Cu, Co, and Sr solutions in the presence of a substrate.

Weight-of-Evidence Approach for Assessing Removal of Metals from the Water Column for Chronic Environmental Hazard Classification.

The United Nations and the European Union have developed guidelines for the assessment of long-term (chronic) chemical environmental hazards. This approach recognizes that these hazards are often related to spillage of chemicals into freshwater environments. The goal of the present study was to examine the concept of metal ion removal from the water column in the context of hazard assessment and classification.

The Fate of Copper Added to Surface Water: Field, Laboratory, and Modeling Studies.

The fate and effects of copper in the environment are governed by a complex set of environmental processes that include binding to inorganic and organic ligands in water, soil, and sediments. In natural waters, these interactions can limit copper bioavailability and result in copper transport from the water column to the sediment. In the present study, data on the fate of copper added to lakes, microcosms, and mesocosms were compiled and analyzed to determine copper removal rates from the water column.

Modeling the Fate of Metal Concentrates in Surface Water.

Metals present in concentrates are in a solid form and are not bioavailable, but they can dissolve or potentially transform to more soluble forms. Transformation/dissolution laboratory protocols have been developed to assess the importance of dissolution of sparingly soluble metal substances in the context of hazard classification; however, these tests represent worst-case scenarios for metal bioavailability because attenuation mechanisms such as complexation, sorption, and transport to the sediment are not considered. A unit world model (UWM) for metals in lakes, tableau input coupled kinetics equilibrium transport (TICKET)-UWM, has been developed that considers key processes affecting metal transport, fate, and toxicity including complexation by aqueous inorganic and ligands, partitioning to dissolved organic carbon (DOC) and particulate organic carbon (POC), precipitation, and transport of dissolved metals and solids between the water column and sediment.

The Use of Mechanistic Population Models in Metal Risk Assessment: Combined Effects of Copper and Food Source on Lymnaea stagnalis Populations.

Environmental risk assessment (ERA) of chemicals aims to protect populations, communities, and ecosystems. Population models are considered more frequent in ERA because they can bridge the gap between the individual and the population level. Lymnaea stagnalis (the great pond snail) is an organism that is particularly sensitive to various metals, including copper (Cu).

An analysis of potential bias in the sensitivity of toxicity data used to construct sensitivity distributions for copper.

Since the mid-1970s, thousands of studies have evaluated the toxicity of various chemicals to aquatic organisms. Results from many of these studies have been used to develop species sensitivity distributions (SSDs) or genus sensitivity distributions (GSDs) for deriving water quality guidelines. Recently, there has been more emphasis on evaluating the toxicity of chemicals to sensitive organisms rather than the entire range of sensitivities.

Assessing Compliance of European Fresh Waters for Copper: Accounting for Bioavailability.

This study determines the levels of compliance of European fresh waters with a bioavailability-based copper Environmental Quality Standard (EQS). A tiered approach for compliance assessment is used at which the first tier compares the dissolved metal concentration to a threshold, estimated using either regional or continental water chemistry data. At the second tier, the bioavailable metal concentration is calculated using the chemistry of the water body, and compared to the EQS for copper.

Internal Loading and Redox Cycling of Sediment Iron Explain Reactive Phosphorus Concentrations in Lowland Rivers.

The phosphate quality standards in the lowland rivers of Flanders (northern Belgium) are exceeded in over 80% of the sampling sites. The factors affecting the molybdate reactive P (MRP) in these waters were analyzed using the data of the past decade (>200 000 observations). The average MRP concentration in summer exceeds that winter by factor 3.

Polyphosphates and Fulvates Enhance Environmental Stability of PO-Bearing Colloidal Iron Oxyhydroxides.

Iron oxyhydroxide nanoparticles (Fe-NPs) are natural vectors of phosphate (PO) in the environment. Their mobility is determined by colloidal stability, which is affected by surface composition. This might be manipulated in engineered NPs for environmental or agricultural applications.

Iron-rich colloids as carriers of phosphorus in streams: A field-flow fractionation study.

Colloidal phosphorus (P) may represent an important fraction of the P in natural waters, but these colloids remain poorly characterized. In this work, we demonstrate the applicability of asymmetric flow field-flow fractionation (AF4) coupled to high resolution ICP-MS for the characterization of low concentrations of P-bearing colloids. Colloids from five streams draining catchments with contrasting properties were characterized by AF4-ICP-MS and by membrane filtration.

Phosphate binding by natural iron-rich colloids in streams.

Phosphorus (P) in natural waters may be bound to iron (Fe) bearing colloids. However, the natural variation in composition and P binding strength of these colloids remain unclear. We related the composition of "coarse colloids" (colloids in the 0.

Impact of dry-wet and freeze-thaw events on pesticide mineralizing populations and their activity in wetland ecosystems: A microcosm study.

Riparian wetlands are proposed to mitigate diffuse pollution of surface water by pesticides in agricultural landscapes. Wetland ecosystems though are highly dynamic environments and seasonal disturbances such as freezing and drying can affect microbial population sizes in the sediment and their functionality including pesticide biodegradation, which has hardly been studied. This study examined the effect of artificially induced dry-wet or freeze-thaw events on the mineralization of the pesticides isoproturon (IPU) and 2-methoxy-4-chlorophenoxy acetic acid (MCPA) in wetland microcosms, either without or with prior enrichment of IPU/MCPA degrading populations.

Body distribution of SiO₂-Fe₃O₄ core-shell nanoparticles after intravenous injection and intratracheal instillation.

Nano-silicon dioxide (SiO2) is used nowadays in several biomedical applications such as drug delivery and cancer therapy, and is produced on an industrial scale as additive to paints and coatings, cosmetics and food. Data regarding the long-term biokinetics of SiO2 engineered nanoparticles (ENPs) is lacking. In this study, the whole-body biodistribution of SiO2 core-shell ENPs containing a paramagnetic core of Fe3O4 was investigated after a single exposure via intravenous injection or intratracheal instillation in mice.

Vanadium bioavailability in soils amended with blast furnace slag.

Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil.