Labile Copper Concentrations Research Articles

Assessement of the heavy metal contamination of soils in Kondopoga and Kostomuksha (Republic of Karelia)

Surveys were carried out in Kondopoga and Kostomuksha, where the main industries are pulp-and-paper making and iron ore mining and concentration, respectively. Samples were taken from the top 0–10 cm soil layer in sites belonging to different land use categories and the content of heavy metals (Pb, Cu, Zn, Ni, Co, Cr, Mn) in the samples was determined by atomic absorption spectrophotometry (Aqua Regia extract). In addition, subsidiary soil pits were made for sampling at 0–5, 5–10, and 10–20 cm depths. These samples were analyzed for physico-chemical properties and heavy metal content. The results showed a relatively low level of heavy metal pollution of soil in the mentioned towns. Surveys in Kondopoga revealed limited general-use areas containing some elements in concentrations exceeding Russian national maximum allowable (MAC) and tentative allowable (TAC) levels (Pb – 6x MAC, Cu – 9x TAC, Zn – 16x TAC), and with labile copper and zinc concentrations up to 2x–3x MAC. Soils of Kostomuksha exhibited relatively low levels of the analyzed heavy metals with concentrations generally not exceeding the regional background in all land use categories. It was only occasionally that pollutant concentrations (Pb, Ni, Cu, Zn) reached 1–2x MAC/TAC. The resultant data can be used in the monitoring of urban soils and for working out recommendations for environmental protection.

Probabilistic risk assessment of mine-derived copper in the Ok Tedi/Fly River, Papua New Guinea

The Ok Tedi mine discharges waste rock and tailings into the Ok Tedi River in Papua New Guinea. This has resulted in elevated copper concentrations throughout the Ok Tedi/Fly River system, which can potentially impact aquatic biota. Ten years of measured copper and toxicity monitoring data were used to assess the risk of chronic effects from the mine-derived copper. Cumulative probability plots of dissolved and labile copper were compared to a species sensitivity distribution (SSD) of published copper toxicity data for four regions of the river. The Cu-SSD was used to estimate the risk of chronic effects to aquatic organisms in the Ok Tedi/Fly River at a range of potential copper exposure scenarios. The risk to species at the median labile copper concentration for each region showed a gradient effect with distance downstream from the mine and only the most sensitive (0.2–11%) species were at risk. There were copper exceedances of the region-specific guideline values (GV) and default guideline value (DGV) 88% and 74% of the time, respectively, in the Ok Tedi region (closest to the mine) and this is considered a high risk of chronic effects. Measured copper concentrations in the middle Fly River, lower Fly River (farthest downstream of the mine) and the river at Kiunga (reference site) exceeded the region-specific GVs and DGVs less frequently to rarely and present a lower risk of chronic effects from copper. The risk was supported using toxicity tests with the local microalgal species Chlorella sp. Comparison of recent (2010−2020) and historical (1996–2004) copper monitoring data from the Ok Tedi/Fly River indicates a decrease in the labile copper concentrations (30–76%) at key sites from impacted regions and a subsequent decrease in risk. This coincides with improved mining practices aimed at reducing the copper load into the Ok Tedi/Fly River.

The use of time-averaged concentrations of metals to predict the toxicity of pulsed complex effluent exposures to a freshwater alga

Intermittent, fluctuating and pulsed contaminant discharges may result in organisms receiving highly variable toxicant exposures. This study investigated the toxicity of continuous and pulsed exposures of a complex, neutralised drainage water (NDW) and dissolved copper-spiked dilute NDW to the green alga, Pseudokirchneriella subcapitata. The effects of single pulses of between 1 and 48 h duration and continuous exposures (72 h) on algal growth rate inhibition were compared on a time-averaged concentration (TAC) basis. Algal growth rates generally recovered to control levels within 24–48 h of the pulse removal. Continuous exposures to NDW resulted in similar or marginally higher toxicity to the algae when compared to pulsed exposures of equivalent TAC (% NDW). The toxicity of the NDW was attributed mostly to the metals, with the major cations potentially causing effects that are both additive (direct toxicity) and antagonistic (lower bioavailability of trace metals). For dissolved copper in dilute NDW, the pulsed exposures caused slightly higher toxicity than continuous exposures of equivalent dissolved copper TAC, with much of the difference explained by differences in labile copper concentrations between treatments. The results indicate that water quality guideline values for toxicants derived from continuous chronic exposures may be relaxed for pulsed exposures by a factor related to the TAC with the intent to provide an adequately protective but not overly-conservative outcome. The study highlights the influence that natural water quality parameters such as water hardness and DOC can have metal speciation and toxicity, and indicates that these parameters are particularly important for site-specific water quality guideline value derivation where, on a TAC basis, pulsed exposures may be more toxic than continuous exposures typically used in guideline value derivation.

Copper-mediated DNA damage by the neurotransmitter dopamine and L-DOPA: A pro-oxidant mechanism

Oxidative DNA damage has been implicated in the pathogenesis of neurological disorders, cancer and ageing. Owing to the established link between labile copper concentrations and neurological diseases, it is critical to explore the interactions of neurotransmitters and drug supplements with copper. Herein, we investigate the pro-oxidant DNA damage induced by the interaction of L-DOPA and dopamine (DA) with copper. The DNA binding affinity order of the compounds has been determined by in silico molecular docking. Agarose gel electrophoresis reveals that L-DOPA and DA are able to induce strand scission in plasmid pcDNA3.1 (+/−) in a copper dependent reaction. These metabolites also cause cellular DNA breakage in human lymphocytes by mobilizing endogenous copper, as assessed by comet assay. Further, L-DOPA and DA-mediated DNA breaks were detected by the appearance of post-DNA damage sensitive marker γH2AX in cancer cell lines accumulating high copper. Immunofluorescence demonstrated the co-localization of downstream repair factor 53BP1 at the damaged induced γH2AX foci in cancer cells. The present study corroborates and provides a mechanism to the hypothesis that suggests metal-mediated oxidation of catecholamines contributes to the pathogenesis of neurodegenerative diseases.

Diffusive Milli-Gels (DMG) for in situ assessment of metal bioavailability: A comparison with labile metal measurement using Chelex columns and acute toxicity to Ceriodaphnia dubia for copper in freshwaters

Fluctuations in concentrations of bioavailable metals occur in most natural waters. In situ measurements are desirable to predict risks of adverse effects to aquatic organisms. We evaluated Diffusive Milli-Gels (DMG), a new in situ passive sampler, for assessing the bioavailability and toxicity of copper in waters exhibiting a wide range of characteristics. The performance was compared to an established Chelex-column method that measures labile copper concentrations by discrete sampling, and the ability to predict acute toxicity to the cladoceran, Ceriodaphnia dubia. The labile copper concentrations measured by the DMG and Chelex-column methods decreased with increasing dissolved organic carbon (DOC) (1.9–15 mg L−1) and hardness (21–270 mg CaCO3 L−1 hardness), with 20–70% of total dissolved copper being present as labile copper. Toxicity decreased with increasing DOC and hardness. Strong linear relationships existed between the EC50 for C. dubia and DOC, and when the EC50 was related to either the labile copper concentrations measured by DMG (r2 = 0.874) or the Chelex column (0.956) methods. The study demonstrates that the DMG passive sampler is a relevant tool for the in situ assessment of environmental risks posed by metals whose toxicity is strongly influenced by speciation.

Measurement of labile copper in wine by medium exchange stripping potentiometry utilising screen printed carbon electrodes

The presence of copper in wine is known to impact the reductive, oxidative and colloidal stability of wine, and techniques enabling measurement of different forms of copper in wine are of particular interest in understanding these spoilage processes. Electrochemical stripping techniques developed to date require significant pretreatment of wine, potentially disturbing the copper binding equilibria. A thin mercury film on a screen printed carbon electrode was utilised in a flow system for the direct analysis of labile copper in red and white wine by constant current stripping potentiometry with medium exchange. Under the optimised conditions, including an enrichment time of 500s and constant current of 1.0μA, the response range was linear from 0.015 to 0.200mg/L. The analysis of 52 red and white wines showed that this technique generally provided lower labile copper concentrations than reported for batch measurement by related techniques. Studies in a model system and in finished wines showed that the copper sulfide was not measured as labile copper, and that loss of hydrogen sulfide via volatilisation induced an increase in labile copper within the model wine system.

Evaluating Copper Behavior in Urban Surface Waters Under Anthropic Influence. A Case Study from the Iguaçu River, Brazil

The goal of this work was to investigate the changes in copper behavior in Iguacu River, a body of water strongly affected by urban inputs. This work was carried out in a subtropical Brazilian watershed suffering with high loads of raw sewage discharges from the Metropolitan Region of Curitiba. A comparison between sampling sites located upstream and downstream from the urban region revealed that human inputs are able to modify the water chemistry of the river in a short distance basis, that is, approximately nine miles. Probably, the most important alterations were the creation of an anaerobic environment as well as the enhancement of humic-coated suspended solids. These two aspects were determinant to explain the high concentrations observed for particulate copper (57% of total recoverable copper) and dissolved copper sulfide species (13%) in the water column. Copper in the sediment was also higher in the downstream site, probably due to the sedimentation of the Cu-enriched particles. However, copper sulfides at the bottom sediment may also be a potential source for the metal in the water column due to the creation of anaerobic conditions in both compartments. Labile copper concentration was not affected by the changes in water chemistry. Despite the fact that sewage discharges motivate the enhancement of organic matter, but not the increase in potential complexing agents, additional ligands such as chloride, carbonates, and anthropogenic dissolved organic ligands can be now computed as a part of the labile fraction.

Copper speciation survey from UK marinas, harbours and estuaries

The use of copper in antifouling paints has increased in the UK in the last 20 years as TBT and several other organic biocides have been phased out. To assess the probable impact of copper on estuarine systems a survey was undertaken to measure the different fractions of copper present in the water column at current usage. The different fractions measured were; labile copper, (LCu) considered as both the free copper ions and inorganically bound copper, the total dissolved copper (TDCu) present, and the difference between them taken as the organically bound likely non-toxic copper fraction. The survey considered sites with different levels of boat use, namely marinas, harbours and estuaries, differing physical parameters of suspended and dissolved organic matter, different seasons of the year and different depths in the water column all of which control speciation behaviour. Suspended particulate matter (SPM) values were measured at all sites and increased from West to East coast locations (5.7–34.4 mg/l). Dissolved organic matter (DOM) values ranged from 0.58 to 2.2 mg/l C. The total dissolved copper concentrations ranged from 0.30 to 6.68 μg/l, with labile fraction ranging from 0.02 to 2.69 μg/l, and most labile copper concentrations below 1 μg/l. None of the yearly mean copper measurements exceeded the 76/464/EEC EQS of 5 μg/l. Of the 306 measurements, only one dissolved copper value in one season was above 5 μg/l. This ratio of labile to total copper was between 10 and 30%. The results from this survey suggest that if toxicity of copper is due to the labile fraction then using the total dissolved copper concentrations as an indicator of impact overestimate the risk by a factor of four times.

Copper complexation by fulvic acid affects copper toxicity to the larvae of the polychaete Hydroides elegans

Copper toxicity is influenced by a variety of environmental factors including dissolved organic matter (DOM). We examined the complexation of copper by fulvic acid (FA), one of the major components of DOM, by measuring the decline in labile copper by anodic stripping voltammetrically (ASV). The data were described using a one-site ligand binding model, with a ligand concentration of 0.19micromol site mg(-1) C, and a logK' of 6.2. The model was used to predict labile copper concentration in a bioassay designed to quantify the extent to which Cu-FA complexation affected copper toxicity to the larvae of marine polychaete Hydroides elegans. The toxicity data, when expressed as labile copper concentration causing abnormal development, were independent of FA concentration and could be modeled as a logistic function, with a 48-h EC(50) of 58.9microgl(-1). However, when the data were expressed as a function of total copper concentration, the toxicity was dependent on FA concentration, with a 48-h EC(50) ranging from 55.6microgl(-1) in the no-FA control to 137.4microgl(-1) in the 20mgl(-1) FA treatment. Thus, FA was protective against copper toxicity to the larvae, and such an effect was caused by the reduction in labile copper due to Cu-FA complexation. Our results demonstrate the potential of ASV as a useful tool for predicting metal toxicity to the larvae in coastal environment where DOM plays an important role in complexing metal ions.

Medium Exchange Stripping Potentiometry for the Measurement of Labile Copper in White Wine

AbstractAn efficient and effective procedure is described for the determination of the labile copper concentration in untreated white wine using medium exchange stripping potentiometry. Two rinse steps between the enrichment and stripping steps allowed measurement of labile concentration with good repeatability and reproducibility. The fraction of labile copper ranged from 13% to 91%, for 16 white wines, indicating the highly variable copper complexing character of the wine matrix. The methodology was applied to labile copper measurement during the oxidation of white wines.

Trace metal speciation measurements in waters by the liquid binding phase DGT device

The speciation measurements of trace metals by the diffusive gradients in thin-films technique (DGT) using a poly(4-styrenesulfonate) (PSS) aqueous solution as a binding phase and a cellulose dialysis membrane (CDM) as a diffusive layer, CDM-PSS DGT, were investigated and showed good agreement with computer modelling calculations. The diffusion coefficients of ethylenediaminetetraacetic acid (EDTA) complexes with Cd 2+ and Cu 2+ were measured and compared with those of the inorganic metal ions. CDM-PSS DGT device was tested for speciation measurement in sample solutions containing EDTA, tannic acid (TA), glucose (GL), dodecylbenzenesulfonic acid (DBS) and humic acid (HA) as complexing ligands forming organic complexes with varying stability constants. Lower percentages of DGT labile copper concentrations over total filterable copper concentrations obtained from the deployments in freshwater sites indicated that copper complexes with organic matter were basically not measured by the devices.

A Comparison of Copper Speciation Measurements with the Toxic Responses of Three Sensitive Freshwater Organisms

Environmental Context.A rapid Chelex resin method is shown to be a valuable speciation screening tool for use in a tiered risk assessment of copper toxicity in fresh waters. It is a more conservative measure than toxicity testing with sensitive biota, but a better indicator of toxicity than a dissolved copper measurement. Abstract.Twelve natural fresh waters with similar pH and hardness, but varying dissolved organic carbon (DOC) and copper concentrations, were assessed for (a) toxicity to an alga (Chlorella sp. 12), a cladoceran (Ceriodaphnia cf. dubia) and a bacterium (Erwinnia sp.), and (b) copper speciation using a rapid Chelex extraction method, diffusive gradients in thin films (DGT) and anodic stripping voltammetry (ASV). In synthetic fresh water with no added DOC, at pH 7.0 and low hardness, the toxic responses (EC/IC50) of all three organisms to copper were similar. However, in the toxicity of copper added to natural water samples exhibited a negative linear relationship to DOC (r2 = 0.82–0.83), with respective slopes for algae, cladocerans and bacteria decreasing in the ratio 7.4 : 3.5 : 1. The marked difference in responses in the presence of natural dissolved organic matter indicated that not all of the organisms conformed to the free ion activity model (FIAM). This was confirmed by copper ion selective electrode measurement of copper ion activity. Copper toxicity to algae in the presence of DOC was overestimated by free ion activity possibly due to surface binding of DOC. Copper toxicity to the bacteria was greater than predicted and was shown to be a result of bioavailability of some copper complexes formed with organic matter. Cladocerans appear to more closely follow FIAM predictions. These findings have important implications for attempts to extend predictive models of metal toxicity beyond fish to more sensitive freshwater species. The measured labile copper concentrations of copper-spiked natural waters varied from 0 to 70% of total copper concentrations. There was no clear relationship between the three measurement techniques. Good correlations were obtained between both algal and bacterial growth inhibitions measured on copper-spiked natural waters and the corresponding Chelex-labile copper concentrations. A single natural water sample was manipulated to different pH and hardness values, spiked with copper, and tested using the above three organisms with the Chelex method. Toxicity test results generally agreed with studies performed in synthetic fresh waters, showing that the relationships between toxicity, pH and hardness were organism-specific. Chelex-labile copper was always over-predictive of toxicity but significantly better (P ≤ 0.05) than dissolved copper concentrations, as it only detects the fraction of total copper that is reactive over biologically-relevant timescales. Colloidally-bound copper and copper associated with strong ligands are not detected. The Chelex method is therefore useful as a measure where speciation is accepted in water quality regulations.

Reduction in labile copper in the 7-day Ceriodaphnia dubia toxicity test due to the interaction with zooplankton food

Due to the increased popularity of zooplankton toxicity tests, it is important to investigate potential confounding factors. Though zooplankton food has been studied extensively to meet the nutritional needs of the zooplankton, less research has been done on whether food addition reduces the toxicity of metals in the tested sample. This investigation combines toxicity tests and metal speciation analysis to determine whether the EPA recommended food of YCT (yeast, cerophyll, and trout chow) and Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) reduces copper toxicity by decreasing the concentration of labile copper. Toxicity tests were performed with Ceriodaphnia dubia on culture water spiked with 0, 787, and 1574 nM copper with five different food levels. A Chelex-100 cation exchange resin and a graphite furnace-atomic absorption spectrophotometer were used in conjunction with the toxicity tests to measure the amount of labile copper in the culture water. At the EPA recommended food dosage, the C. dubia food has a chelating capacity of approximately 500 nM Cu. For both concentrations of spiked culture water, the toxicity to C. dubia was reduced with increasing food level, which seemed to be both from a decrease in labile copper concentration and an increase in the nutritional condition of the zooplankton.

Pulse Disturbances to the Colonization of Hard-substrates and in situ Determination of Copper using Diffusive Gradients in Thin-films (DGT): Quantifying Dose and Response in the Field

Studies conducted in Port Philip Bay, Victoria, Australia are described that examined the effect of experimentally elevated copper concentrations on the recruitment of epifauna to settlement plates. Simultaneous measurement of the copper concentration using diffusive gradients in thin films (DGT) allowed direct comparisons to be made between the labile copper concentration measured at the settlement surface, and the biological effects observed. Copper concentrations created by the field dosing technique were between 20 – 30 μg l−1 for the first 2 d, but then dropped considerably for the following 4 d (3 μg l−1), and were indistinguishable from background for the final 7 d. The first 2 d of a copper pulse reduced the recruitment of barnacles, ascidians, serpulid worms, an encrusting bryozoan, and didemnid ascidians. The impacts occurred despite the copper pulse being much less than published LC50 values for similar species. The impacts were no longer obvious by day 7 or 14, having been obscured by either high mortality of early settlers, or large settlement events that took place after day 2. Thus the greatest impact of the pollution event occurred during the period of highest toxicant concentration. The value of this study lies in the correlation of toxicity effects with bio-available metal concentrations under realistic (natural, in situ) conditions.

Copper speciation in Iguaçu river basin, at Curitiba's metropolitan region, Brazil, by ligand competition using DPASV

Copper concentrations and speciation in two different sites located in the Iguacu River Basin, Brazil, were evaluated during a 10-months period, in this work. Results showed a seasonal influence on copper levels with a major contribution of non-point sources during the rainy season, when concentrations of copper were similar in both Irai and Iguagu Rivers. During the dry season the discharge of raw sewage was the primary source of copper for the sampling point located downstream the city of Curitiba, in the Iguacu River, which exhibited higher metal concentrations. Speciation results also showed different patterns. Higher copper contents were found in the particulate phase in Iguacu River, whereas labile copper concentrations were relatively greater in Irai River waters.

Copper bioavailability and amelioration of toxicity in Macquarie Harbour, Tasmania, Australia

The 100-year operation of the Mount Lyell Mining and Railway Company Limited’s copper mine in Queenstown, Australia, has resulted in the deposition of over 100 million cubic metres of mine tailings, smelter slag and topsoil into the King River and Macquarie Harbour. Apreliminary risk assessment, together with chemical measurements of dissolved copper, ASV-labile copper, copper complexing capacity and resin-adsorbed copper, suggested that copper in mid-salinity harbour waters was potentially bioavailable. However, toxicity tests based on inhibition of microalgal (Nitzschia closterium) growth showed that copper in these waters was not toxic, even though labile copper concentrations (6–24 µg L−1) exceeded the concentration of lowest observable effect for algae of 5 mg L−1. Measurements of intracellular and membrane-bound copper confirmed that cell division was not affected because copper was not taken up intracellularly. Amelioration of copper toxicity was due to binding of dissolved organic matter and/or other metals at the cell membrane, preventing copper binding and uptake. An understanding of the mechanism of copper toxicity and its amelioration is vital to assessing various clean-up options for the harbour.

Evidence for Strong Copper(I) Complexation by Organic Ligands in Seawater

Thiols like glutathione and cysteine form such stable complexes with copper(I) that they preclude the presence of copper(II). Conventionally seawater is titrated with copper(II) whilst monitoring the labile or reactive copper concentration by voltammetry or with other techniques, to determine the concentration of copper(II) binding complexing ligands in seawater. Titrations of seawater to which copper(I) binding ligands have been added reveal that the copper(I) binding ligands are detected when seawater is titrated with copper(II). The copper(II) in seawater is reduced to copper(I) within 2 to 40 minutes depending on the nature of the copper(I) binding ligand. The titrations of seawater with copper(II) thus give a response to the presence of copper(I) binding ligands indiscernible from that for copper(II) binding ligands. The stoichiometry of the detected apparent ligand concentrations for given concentrations of glutathione and cysteine suggest that 2 : 1 (thiol : Cu) complexes are formed. This was confirmed using voltammetry of free glutathione. Values of 21.2 and 22.2 were found for log β″CuL for glutathione and cysteine respectively (for the reaction of Cu′ + 2L′ ↔ CuL2). The complex stability is similar to that of natural organic species in the oceanic water column. The high stability of the copper(I) complexes was apparent from values of 32.1 and 32.6 for log β″Cu(I)L2 (for the reaction Cu+ + 2L″ ↔ CuL2) for the copper(I) complexes with glutathione and cysteine in seawater. Glutathione and other thiols are common in the marine system including the water column. It is therefore possible that at least some of the ligands detected in seawater, and previously assumed to be copper(II) binding ligands, are in fact strongly complexed as copper(I). The copper(I) oxidation state may thus be stabilised in seawater.

Determination of free and total copper and lead in wine by stripping potentiometry

Stripping potentiometry has been employed for the measurement of the labile and total copper concentrations in white wine. Conditions have been optimised for a supporting electrolyte consisting of 1.0 mol/L hydrochloric acid and 0.5 mol/L calcium chloride. Mercury(II) was found to be a more suitable oxidant than O2 and, for the determination of the labile concentrations, this required the use of medium exchange. With lead, O2 proved to be an efficient oxidant for the stripping step and this allowed the direct measurement in the wine without the need for medium exchange. It was observed that red wine rapidly binds added lead, demonstrating that wine has a high complexation capacity for lead. A similar complexation effect was also observed for white wine, but the degree of lead complexation was less than that for red wine. The impact of this lead complexation effect for the use of standard additions is discussed.

Effects of dilution on the complexation of metal ions in wastewaters from a fishmeal factory

The effects of dilution on the complexation of metal ions by the organic matter dissolved in effluent from a fishmeal factory were studied at pH 6.5, 7 and 7.5. The relationship between sample dilution and complexation capacity (determined by titration with copper(II) using DPASV to measure the concentration of labile copper) was linear and with a slope apparently independent of pH.

Toxicity effects of copper (II) on the marine dinoflagellateAmphidinium carterae: Influence of metal speciation

The influence of copper(II) concentration and speciation on the growth of Amphidinium carterae in batch culture in a modified ESAW medium was evaluated by two different experimental designs: (i) copper(II) was added to the cultures 2 h after cell inoculation and (ii) copper(II) had a 24 h pre-equilibration period in the medium before cell inoculation. To complement the biological data, the following information on the chemical/biological system was obtained: (a) computational speciation of the culture medium under chemical equilibrium conditions: (b) total and electrochemically labile copper concentrations in the culture medium during the toxicity experiments; and (c) cellular levels of copper. The labile fraction of copper was measured by potentiometric stripping analysis (PSA) at a deposition potential (E d) of — 0·3 V. At this E d the dissociation of Cu-EDTA complexes was negligible. In both kinds of experiments the effects of copper were more evident after 4 days than after 7 or 10 days of exposure. W...