Dissolved Metal Concentrations Research Articles

Assessing variability in the ratio of metal concentrations measured by DGT-type passive samplers and spot sampling in European seawaters

The current study evaluates the effect of seawater physico-chemical characteristics on the relationship between the concentration of metals measured by Diffusive Gradients in Thin films (DGT) passive samplers (i.e., DGT-labile concentration) and the concentrations measured in discrete water samples. Accordingly, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to measure the total dissolved metal concentrations in the discrete water samples and the labile metal concentrations obtained by DGT samplers; additionally, lead and cadmium conditional labile fractions were determined by Anodic Stripping Voltammetry (ASV) and total dissolved nickel was measured by Cathodic Stripping Voltammetry (CSV). It can be concluded that, in general, the median ratios of DGT/ICP and DGT/ASV(CSV) were lower than 1, except for Ni (median ratio close to 1) and Zn (higher than 1). This indicates the importance of speciation and time-integrated concentrations measured using passive sampling techniques, which is in line with the WFD suggestions for improving the chemical assessment of waterbodies. It is the variability in metal content in waters rather than environmental conditions to which the variability of the ratios can be attributed. The ratios were not significantly affected by the temperature, salinity, pH, oxygen, DOC or SPM, giving a great confidence for all the techniques used. Within a regulatory context such as the EU Water Framework Directive this is a great advantage, since the simplicity of not needing to use corrections to minimize the effects of environmental variables could help in implementing DGTs within monitoring networks.

Enrichment of Trace Metals (V, Cu, Co, Ni, and Mo) in Arctic Sediments—From Siberian Arctic Shelves to the Basin

AbstractWith 50% of the Arctic Ocean is consisted of continental shelves, extensive shelf‐basin exchange processes exist here and plays a key role in regulating the biogeochemical recycling process of trace metals in the Arctic region. In this study, short sediment cores were collected along three transects from Siberian‐Chukchi shelves to adjacent slope/basin areas. An increasing trend was found for the bulk concentrations of several metals (V, Cu, Co, Ni, and Mo) from shelf to slope/basin cores with increasing water depth. Sequential extraction experiments indicated that the Fe/Mn oxide fractions increased significantly from shelf (9%–21%) to basin cores (24%–76%) for Cu, Co, Ni, and V, while the organic/sulfide phase remained significant (∼40%) for Mo. In addition, the observed dissolved metal concentrations in porewater indicated the remobilization of Fe, Mn, and Mo from shelf sediment, while V was always removed from water to the sediment, both on the shelf or in the slope/basin. Overall, in combination with the statistical analysis, we proposed that metals are transported from shelves to the central Arctic and are scavenged mainly by Mn oxides from the water column, which results in the enrichment of metals in slope/basin sediment. With the climate change, such transport and accumulation mechanism may be intensified over time, slowly leading the Arctic sediment to be a more and more important sink for those metals.

Development of Quantitative Ion Character-Activity Relationship Models to Address the Lack of Toxicological Data for Technology-Critical Elements.

Recent industrial developments have resulted in an increase in the use of so-called technology-critical elements (TCEs), for which the potential impacts on aquatic biota remain to be evaluated. In the present study, quantitative ion character-activity relationships (QICARs) have been developed to relate intrinsic metal properties to their toxicity toward freshwater aquatic organisms. In total, 23 metal properties were tested as predictors of acute median effect concentration (EC50) values for 12 data-rich metals, for algae, daphnids, and fish (with and without species distinction). Simple and multiple linear regressions were developed using the toxicological data expressed as a function of the total dissolved metal concentrations. The best regressions were then tested by comparing the predicted EC50 values for the TCEs (germanium, indium, gold, and rhenium) and platinum group elements (iridium, platinum, palladium, rhodium, and ruthenium) with the few measured values that are available. The 8 "best" QICAR models (adjusted r2 > 0.6) used the covalent index as the predictor. For a given metal ion, this composite parameter is a measure of the importance of covalent interactions relative to ionic interactions. Toxicity was reasonably well predicted for most of the TCEs, with values falling within the 95% prediction intervals for the regressions of the measured versus predicted EC50 values. Exceptions included Au(I) (all test organisms), Au(III) (algae and fish), Pt(II) (algae, daphnids), Ru(III) (daphnids), and Rh(III) (daphnids, fish). We conclude that QICARs show potential as a screening tool to review toxicity data and flag "outliers," which might need further scrutiny, and as an interpolating or extrapolating tool to predict TCE toxicity. Environ Toxicol Chem 2021;40:1139-1148. © 2020 SETAC.

Delivery of Metals and Dissolved Black Carbon to the Southern California Coastal Ocean via Aerosols and Floodwaters Following the 2017 Thomas Fire

AbstractThe Thomas Fire began on December 4, 2017 and burned 281,893 acres over a 40‐day period in Ventura and Santa Barbara Counties, making it one of California's most destructive wildfires to date. A major rainstorm then caused a flash flood event, which led to the containment of the fire. Both airborne ash from the fire and the runoff from the flash flood entered into the Santa Barbara Basin (SBB). Here, we present the results from aerosol, river, and seawater studies of black carbon and metal delivery to the SBB associated with the fire and subsequent flash flood. On day 11 of the Thomas Fire, aerosols sampled under the smoke plume were associated with high levels of PM2.5, levoglucosan, and black carbon (average: 49 μg/m3, 1.05 μg/m3, and 14.93 μg/m3, respectively) and aerosol metal concentrations were consistent with a forest fire signature. Metal concentrations in SBB surface seawater were higher closer to the coastal perimeter of the fire (including 2.22 nM Fe) than further off the coast, suggesting a dependence on continental proximity rather than fire inputs. On days 37–40 of the fire, before, during, and after the flash flood in the Ventura River, dissolved organic carbon, dissolved black carbon, and dissolved metal concentrations were positively correlated with discharge allowing us to estimate the input of fire products into the coastal ocean. We estimated rapid aerosol delivery during the fire event to be the larger share of fire‐derived metal transport compared to runoff from the Ventura River during the flood event.

Risk Assessment on Human Health: the Case of Primorsky Krai Abandoned Sulfide-Rich Tailings Dump

To evaluate the human health risk, the Vetvisty creek (Vysokogorsk settlement, Primorsky krai) water quality monitoring was performed, and health risk associated with exposure to metals via oral ingestion was calculated. The results of inductively coupled plasma-mass spectrometry analyses for six samples collected in May, August, and November 2019 demonstrated a spatial variation of dissolved metals concentrations in the Vetvisty creek flow at stations before and after the tailings dam. The obtained characteristics of creek water samples allowed us to reveal, that the greatest contribution to carcinogenic risk is made is made by arsenic (up to 0.00160 mg/L and 2,99×10−5 of individual lifetime risk). The obtained cancer risk associated with exposure to metals via oral ingestion have the values of 3,17×10−5 and 2.28×10−5 before and after the Vysokogorsk tailings dam, respectively. All the risk levels are in carcinogenic risks range acceptable by United States Environmental Protection Agency and do not require any additional measures except of dissolved metals content control.

Verification of the Determination Method of Dissolved Metal Content using ICP-OES and Its Application for River Water in Bandar Lampung City

Method verification for metal analysis (Cd, Cr, Cu, Ni, Co, and Mn) in surface water using Inductively Coupled Plasma (ICP) was carried out to evaluate the method’s performance in the laboratory-based on US Method EPA 200.7. The verified method is used to determine the metal content in river water flowing in Bandar Lampung. The results showed that the method used had good linearity with a regression coefficient of more than 0.995. This method’s accuracy is expressed by the %RSD (relative standard deviation), which is in the range of 3.145 to 4.345% and meets the acceptance requirements with a %RSD value less than ⅔ CV Horwitz. The method accuracy obtained from the spiking analysis gives a range of 80-110% for the analysis of 1 mg/L and meets the acceptability required by AOAC. Overall, the performance of the method used is suitable for the analysis of metals in surface water. This method was applied for metal analysis in river water samples in several places in Bandar Lampung, which were the Palang Besi river (A1), the Way Balau Kedamaian river (B1), the Way Balau Kedaton river (C1), the Way Kuala river (D1), the Sumur Batu Kahuripan river (E1), Sumur Putri river (F1), and Muara Kahuripan river (G1). The concentrations of Cd, Cr, Cu, Ni, and Co metals were under the LoD method, while the Mn concentration was above the LoD method in river water samples.

Metal Speciation in Water of the Flooded Mine “Arsenic” (Karelia, Russia): Equilibrium-Kinetic Modeling with a Focus on the Influence of Humic Substances

Equilibrium-kinetic modeling allows investigating metal behavior in the water–rock-organic matter system with time to evaluate anthropogenic effects on the environment. In the article, the interactions of stagnant mine drainage water of the flooded mine “Arsenic” with ore and gangue minerals were simulated using different organic matter incorporation approaches. If the model is closed to humic substances (no additional organic matter input), most fulvic acids are bound in the Fe fulvate complex. While under the removal of Fe fulvate from the model, the Cu fulvate becomes prevalent, the contribution of the fulvate complexes with Zn, Mg, and Ca also increases. This scenario simulates the organo-mineral complexes behavior well and allows identifying the sequence of metal binding to organic ligands as follows Fe > Cu > Zn > Mg > Ca. The second scenario imitates the constant input of organic matter to the model (open system regarding humic substances). The dissolved metal concentrations in the model solution are extremely high in comparison to the mine drainage water. This scenario demonstrates that excessive input of organic matter leads to the accumulation of the metals in a dissolved form and blocks the secondary mineral formation despite the faster dissolution of the primary minerals under a more acidic pH than in the first scenario. However, despite the differences between the model solution and the mine drainage water, this scenario is useful to address specific issues associated with changes in natural and anthropogenic conditions. Both scenarios show the importance of organic matter incorporation to the equilibrium-kinetic models.

Diagenetic Processes in Aquaculture Ponds Showing Metal Accumulation on Shrimp Gills

The gill is the organ by which many toxic metals are taken up by crustaceans. Iron is known to precipitate at its surface, a phenomenon recently observed in some tropical aquaculture ponds. The present study uses a field approach to understand better the environmental conditions and ecological processes involved in this deposit. Because shrimp are exposed to reduced products originating from organic waste accumulated in the sediment, spatial variation in pH, redox potential and concentrations of dissolved metals in pore water were investigated in these ponds. Total organic carbon, acid volatile sulfide and pyrite were also analyzed in the solid phase. Fe2+ in pore waters showed high spatial variability between ponds and within the same pond with concentrations up to 1,193 μmol l–1. Behaviors of Fe2+, Mn2+ and Co2+ in pore water were similar. Four geochemical environments were identified, based on their physico-chemical characteristics. Highest concentrations for Fe2+, Mn2+ and Co2+ in sediment pore water occurred in slightly acidic and suboxic conditions. When the sediment became anoxic, the H2S produced reacted with Fe2+ and/or Co2+ to form acid volatile sulfide and pyrite. When pH increased, the concentration of free H2S rose up to 736 μmol l–1. With neutral and suboxic conditions, dissolved metal concentrations could be controlled by their precipitation as oxides and hydroxides. The production of pyrite suggested the existence of a possible process of sediment acidification between two crop periods through the production of sulfuric acid. This acidification could increase with pond age and be the cause of the accumulation of reduced metal after 30 years of aquaculture activity.

Değirmendere Barajı‘nda (Amasya, Türkiye) Suda Tespit Edilen Çözünmüş Metallerin İçme ve Sulama Suyu Kalitesine Olan Etkisinin Değerlendirilmesi

Barajlar; başta enerji üretimi olmak üzere, içme ve sulama suyu ihtiyacının karşılandığı önemli kaynaklardır. Bu çalışmada Amasya ilindeki Değirmendere Baraj suyunda çözünmüş metal konsantrasyonları ICP-MS ile tespit edilmiş ve veriler içme/sulama suyu açısından değerlendirilmiştir. Baraj gölünün 5 farklı noktasından alınan numunelerdeki her bir metalin ortalama miktarı µg/L cinsinden; Ca (50943)> Mg (42212)> Na (31637)> K (3725)> Al (63,68)> Fe (43,30)> Zn (30,78)> Cu (5,79)> Mn (4,59)> Ni (2,97)> Cr (1,18)> Pb (1,14)> As (1,04)> Cd (0,69) olarak tespit edildi. Bu sonuçlar Dünya Sağlık Örgütü (WHO) ve Türk Standartları (TS 266) tarafından önerilen içme suyu limit değerlerini aşmamıştır. Su kalitesi indeksi (WQI), ağır metal kirlilik indeksi (HPI) ve ağır metal değerlendirme indeksi (HEI) değerleri sırasıyla 16,63-17,54-1,00 olarak hesaplanmıştır. Tehlike oranı (HQ), tehlike indeksi (HI) ve kanser riski (CR) açısından baraj gölünün su kalitesi yetişkinler /çocuklar için potansiyel tehlike oluşturmayacak durumdadır. Sodyum absorpsiyon oranı (SAR=0,78) ve sodyum yüzdesi (% Na=19,56) değerlerine göre baraj suyu sulama açısından elverişlidir. Ancak magnezyum zararı (MH=57,70) değeri sulama suyu bakımından 50 olan limit değerin üzerindedir.

Identification of the Potential of Acid Rock Drainage in the Tin Mine on Bangka Island

Bangka Belitung is one of the tin-producing areas in the world which is characterized by the large number of granite rocks in the area as the rock carrying cassiterite minerals. Granite rocks found on Bangka Island are rocks formed due to magma activity from acidic volcanic processes. The availability of acidic water is possible due to the presence of acid-carrying minerals from granite which causes acid rock drainage or acid rock water which generally occurs in mining areas, ex-mining and exploration in tin mines. Before making efforts to prevent environmental pollution, identification is needed regarding the potential acidity of the rock so that the pH and dissolved metal content that endangers survival can be prevented to a minimum.

Comparative ecotoxicity of single and binary mixtures exposures of cadmium and nickel on growth and biomarkers of Lemna gibba.

The aim of the present study was to investigate the toxicity effects of cadmium-nickel (Cd-Ni) after single and mixtures exposures over the macrophyte Lemna gibba. Effects were assessed on growth, as frond number and fresh weight and biochemical parameters, such as total protein content and activity of antioxidant enzymes. Plants were exposed to single Cd and Ni in concentrations that ranged between 0.13-33 mg/L and 0.18 and 11.82 mg/L, respectively. For binary mixtures, individual metal IC50 values were used for selection of the evaluated concentrations. The experimental design consisted in three different ratios based on the concept of toxic units (TU), each ratio was evaluated by five different concentrations. Both single and mixture treatments were performed for 7 days following the conditions according to OECD (2006). Single and mixture exposures affected plant growth and the biomarkers of the antioxidant response. Growth parameters showed a differential sensitivity after individual metal exposures. Cd was more toxic for L. gibba plants when fresh weight was considered, but on the contrary, considering frond number, Ni was the most toxic metal. IC50-7d, based on growth rate calculated on frond number were 17.8 and 2.47 mg/L, and on fresh weight were 1.08 and 3.89 mg/L, for Cd and Ni respectively. LOEC values for Cd were obtained at 2.06 and 1.03 mg/L, for frond number and fresh weight, respectively; while for Ni, these values were 0.92 and 11.82 mg/L. The three evaluated ratios for binary mixtures resulted in a high toxicity considering the same response variables in single metal exposures. Ratio 1 (2/3 TU Cd-1/3 TU Ni) was the most toxic considering both frond number and fresh weight, showing percentage inhibition of growth rates of 96 and 90%, respectively for the highest concentration. A modification of the protein content was observed in single, but especially in the mixture treatments. The activity of catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPOX; EC 1.11.1.7) was also affected in single and mixtures assays. APOX and GPOX showed a higher increase of its activities respect the controls after mixture treatments than for single metal treatments. Such optimization of the antioxidant system could be one of the causes of the antagonistic toxicity observed in mixture exposures. Concentration addition (CA) reference model, based on frond number, in Cd-Ni mixtures was not a good predictor to evaluate toxicity from dissolved metal concentration since the results showed that toxicity was less than additive, with an average of ΣTU = 2.17. The observed antagonisms resulted to be stronger in mixtures with higher metal concentrations.

Evaluating the Performance of a Diffusive Gradient in Thin Film Embedded with Montmorillonite for the Determination of Labile Cd, Pb, Mn, and Zn in Natural River Water

Montmorillonite (MMT), a natural clay mineral with high ion-exchange capacity and trace metal adsorbability, has been demonstrated to be a suitable binding phase in the diffusive gradient in thin film (DGT) technique for the determination of labile trace metals in synthetic water samples. However, in situ working performance of DGT-MMT with natural river water has not yet been investigated. The present study examined the performance of a DGT containing montmorillonite (MMT) for the in situ isolation and determination of labile Cd, Pb, Mn, and Zn fractions in Lach Tray River water, North Vietnam. The repeatability and accuracy of the DGT-MMT probe were assessed on the basis of seven measurement replicates performed on Cd2+, Pb2+, Mn2+, and Zn2+ standard solutions. Then, the DGT-MMT probes were deployed in Lach Tray River water at different sampling sites to determine the labile metal fractions present in river water. By comparing the total and dissolved metal concentrations in the river water, the distributions of the four tested trace metals were constructed. The proportions of the dissolved fractions of Cd, Pb, Mn, and Zn were 46.7–73.7%, 38.5–63.9%, 36.4–41.6%, and 49.8–67.7%, respectively. The results also showed that the high accuracy and reproducibility of the DGT-MMT data were comparable with measurements obtained by the commonly used DGT-Chelex-100 method. In comparison with the data obtained from anodic stripping voltammetry (ASV), a traditional technique for the determination of non-in situ speciation of trace metals, labile metal concentrations measured by DGT-MMT were in similar ranges. These findings indicate that naturally available montmorillonite can be used as an alternative binding material in DGT probes for the in situ determination of labile metal concentrations in natural watercourses.

The influence of urban surface type and characteristics on runoff water quality

Untreated runoff was collected over multiple rain events from 19 impermeable urban surfaces, including nine roofs, six roads and four carparks, to quantify the differences in water quality due to surface type, age, condition and location. All 19 sites were exposed to the same climatic conditions. Samples were analysed for key urban pollutants of concern, namely total suspended solids and total and dissolved copper and zinc. Results showed uncoated zinc-based roofs produced zinc concentrations (up to 55 mg/L) several orders of magnitude higher than receiving environment water quality guidelines in New Zealand, of which the vast majority was in dissolved form. Even non-metallic roofs with zinc-based guttering produced zinc concentrations over ten times higher than the same roof material without zinc-based guttering. Older zinc-based roofs had approximately five times higher zinc concentrations, demonstrating a substantial age effect on the untreated runoff quality. Similarly, copper roofs produced more than an order of magnitude higher copper concentrations (up to 7.8 mg/L) above the next highest copper-producing surfaces: higher trafficked roads and carparks. Regardless of traffic volume or function, all roads and carparks produced high TSS concentrations. Dissolved metal concentrations were high across the dataset confirming that metal partitioning is an important consideration for effective pollutant control as different removal processes need to be used for dissolved versus particulate metals. This dataset provides an important benchmark of untreated runoff quality across different impermeable surface types within the same geographical area and clearly shows the influence of surface characteristics on water quality runoff regardless of the local differences in land use. These findings provide valuable guidance to stormwater managers in identifying priority surfaces and selection of appropriate treatment strategies for effective stormwater management for total suspended solids, zinc and copper.

Assessing Options for Remediation of Contaminated Mine Site Drainage Entering the River Teign, Southwest England

The river Teign in Devon has come under scrutiny for failing to meet environmental quality standards for ecotoxic metals due to past mining operations. A disused mine known as Bridford Barytes mine, has been found to contribute a significant source of Zn, Cd and Pb to the river. Recently, studies have been focused on the remediation of such mine sites using low-cost treatment methods to help reduce metal loads to the river downstream. This paper explores the metal removal efficiency of red mud, a waste product from the aluminium industry, which has proven to be an attractive low-cost treatment method for adsorbing toxic metals. Adsorption kinetics and capacity experiments reveal metal removal efficiencies of up to 70% within the first 2 h when red mud is applied in pelletized form. Further, it highlights the potential of biochar, another effective adsorbent observed to remove >90% Zn using agricultural feedstock. Compliance of the Teign has been investigated by analysing dissolved metal concentrations and bioavailable fractions of Zn to assess if levels are of environmental concern. By applying a real-world application model, this study reveals that compressed pellets and agricultural biochar offer an effective, low-cost option to reducing metal concentrations and thus improving the quality of the river Teign.

Coating of chromium and titanium carbide on diamond particles in molten LiCl–KCl–NaCl

Diamond particles were coated with chromium (Cr) or titanium (Ti) using a molten salt synthesis (MSS) approach involving lithium chloride (LiCl), potassium chloride (KCl), and sodium chloride (NaCl). Diamond and metal powders were heated at 700–900 °C in the MSS to create chromium carbide (Cr7C3) or titanium carbide (TiC) coatings on the diamond particles. Carbide formation was influenced by the dissolved metal content and the diffusion rate. The thickness and morphology of the Cr coating layer was not significantly affected by the molar ratio of the LiCl–KCl–NaCl mixture, however, in terms of the coating atmosphere, it is most valuable using the eutectic LiCl–KCl–NaCl mixture having the molar ratio of 55:33:12 and the lowest melting point. The resulting Cr7C3 and TiC coated surfaces and microstructures were characterized by X-ray diffraction and scanning electron microscopy, respectively. A uniform Cr7C3 and TiC layer formed on the surface of the diamond particles at a relatively low temperature, at which the graphitization of diamond was avoided. The coating layer thickness estimated by particle size analysis increased linearly with coating temperature. The thickness of the Cr- and Ti-coated layers ranged from 1 to 10 and 0.5–1.5 μm, respectively, which indicated that the TiC coating formed at a much slower rate than the Cr7C3 coating.

Comparative ecotoxicity of single and binary mixtures exposures of cadmium and zinc on growth and biomarkers of Lemna gibba.

In the present study, single and mixture effects of cadmium (Cd) and zinc (Zn) on Lemna gibba were analyzed and compared using growth parameters, based on frond number and fresh weight, and biochemical parameters, such as pigment, protein content and activity of antioxidant enzymes. Plants were exposed for 7 days to these metals in nutrient solution. Single and mixture exposures affected plant growth and the biomarkers of the antioxidant response. Considering the growth parameters, Cd was found to be much more toxic than Zn. IC50-7d, based on growth rate calculated on frond number, were 17.8 and 76.73 mg/L, and on fresh weight were 1.08 and 76.93 mg/L, for Cd and Zn respectively. For Cd, LOEC values were obtained at 2.06 and 1.03 mg/L, for frond number and fresh weight respectively; while for Zn, at 20.1 and 74.6 mg/L. A high toxicity effect, considering the same response variables, was observed in plants exposed to the mixtures. Three fixed ratios, based on toxic units (TU) were assayed, ratio 1: 2/3 Cd-1/3 Zn, ratio 2: 1/2 Cd-1/2 Zn and ratio 3: 1/3 Cd-2/3 Zn. Ratio 3 (where Zn was added in higher proportion) was the less toxic. All concentrations of Ratio 1 and 2 significantly inhibited plant growth, showing a 100% inhibition of growth rate at the highest concentrations when based on frond number. Catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPOX; EC 1.11.1.7) activities in single metals assays were higher than controls. In mixture tests, the activity of APOX and GPOX was significantly stimulated in plants exposed to all evaluated combinations, while CAT was mainly stimulated in Ratio 3. It was observed that the activity of the enzymes was increased in the mixtures compared with similar concentrations evaluated individually. APOX activity was observed to fit the CA model and following a concentration-response pattern. The response of this antioxidant enzyme could serve as a sensitive stressor biomarker for Cd-Zn interactions. Frond number in Cd-Zn mixtures was not well predicted from dissolved metal concentration in solution using concentration addition (CA) as reference model, as results showed that toxicity was more than additive, with an average of ΣTU = 0.75. This synergistic effect was observed up to 50 mg Zn/L in the mixture, but when it was present in higher concentrations a less than additive effect was observed, indicating a protective effect of Zn. A synergistic and dose-ratio deviations from CA model were also observed.

Monitoring of mine waste from copper ore flotation

The copper ore flotation conducted by PT XYZ produces copper, and other metal concentrates as tailings. The copper concentrate will then be processed as industrial raw material, while the tailing waste is dumping a waste dump. The copper ore flotation tailings must follow the tailings waste management rules. Monitoring tailings quality testing must be done, which includes physical and chemical parameters. The results of the analysis of copper ore flotation tailings are comparing with the provisions issued by the Ministry of Environment No. 92 of 2011. And 382 in 2016. Furthermore, to monitor the state of seawater around the mining site, water quality testing is divided into three zones, Zone A with into> 120 m, Zone B 0 - 120, and Zone C (tailings free). Seawater quality monitoring is carrying out in zone B. The quality test results tailing flotation Copper ores how physical and chemical parameters are below the threshold set by the Ministry of Environment. Whereas monitoring of seawater quality carried out in zone B, TDS exceeds the intensity at S15B, while dissolved metal concentrations are below the threshold at all stations.

Copper Complexing Capacity and Trace Metal Content in Common and Balsamic Vinegars: Impact of Organic Matter

Complex formation is among the mechanisms affecting metal bioaccessibility. Hence, the quantification of organic metal complexation in food items is of interest. Organic ligands in solutions of environmental and/or food origin function as buffering agents against small changes in dissolved metal concentrations, being able to maintain free metal ion concentrations below the toxicity threshold. Organic matter in vinegars consists of bioactive compounds, such as polyphenols, Maillard reaction endproducts, etc., capable of complexing metal ions. Furthermore, transition metal ions are considered as micronutrients essential for living organisms exerting a crucial role in metabolic processes. In this study, differential pulse anodic stripping voltammetry (DPASV), a sensitive electrochemical technique considered to be a powerful tool for the study of metal speciation, was applied for the first time in vinegar samples. The concentrations of Cu complexing ligands (LT) in 43 vinegars retailed in Greece varied between 0.05 and 52 μM, with the highest median concentration determined in balsamic vinegars (14 μM), compared to that of common vinegars (0.86 μM). In 21% of the vinegar samples examined, LT values were exceeded by the corresponding total Cu concentrations, indicating the presence of free Cu ion and/or bound within labile inorganic/organic complexes. Red grape balsamic vinegars exhibited the highest density of Cu ligands per mass unit of organic matter compared to other foodstuffs such as herbal infusions, coffee brews, and beers. Among the 16 metals determined in vinegars, Pb is of particular importance from a toxicological point of view, whereas further investigation is required regarding potential Rb biomagnification.

A New Method for Corrosion Current Measurement: the Dual-Electrochemical Cell (DEC)

This paper presents the “dual electrochemical cell” (DEC) method, a new technique that allows monitoring of corrosion current () in real time with a corrosion potential that may change with time. In this method, the of a metal corroding in a solution containing the oxidant of interest is measured in the 1st cell. This potential is then continuously applied in real time to a second cell using the same metal electrode in the same solution but free of the oxidant, and the current of the 2nd cell, which represents the of the 1st cell, is monitored. This setup allows direct measurement of without having to polarize the corroding electrode away from The advantages of DEC over conventional methods are that it does not require the corroding system to be at steady state, and avoids any ambiguities associated with the extrapolation of the measured current-potential relationship to extract The values obtained using the DEC method were compared with those obtained using conventional polarization techniques, using dissolved metal concentrations and surface analysis observations, and the results showed that the DEC method provides the most accurate measurement of

Assessment of heavy metal contamination in natural waters of Dereli, Giresun: an area containing mineral deposits in northeastern Turkey.

The concentration of heavy metals in the natural waters of the area surrounding Dereli (Giresun), a mineralized area, was determined. In addition, the physicochemical parameters (such as pH, Eh, and HCO3-) influencing the concentration of dissolved metals in waters were evaluated. Samples were collected from stream, spring, and main river waters, some of which are used by local residents for drinking, fish farming, and animal husbandry. The present data indicate that the water-rock interaction is the main process controlling the chemical composition of waters in the area. The waters are predominantly CaMgHCO3-type waters with alkaline pH values. Heavy metal concentrations (Pb, Zn, Cu, Fe, Mn, U, Cd, As, Hg, Sb, Ni, Co, and Ba) in waters were generally low. Relatively high values of certain metals were determined in waters of the Kotana and Kurtulmus sites of Dereli. The levels of Pb in the river, stream, and spring water samples in these sites were somewhat higher than the Pb values reported in the literature for natural waters. However, these values only slightly exceeded the Pb water limit values proposed by the USEPA and the WHO. In addition, the concentrations of other heavy metals, except Pb, were fairly similar to those of other natural waters and these values were also under the drinking water limits set by the WHO and the USEPA. This study shows that waters in the area of Dereli were not significantly affected by mineralization. This is most likely caused by the bicarbonate-rich waters affecting the dissolved metal concentrations.