Mixing behaviour and sources of Ag, Pd, and other trace elements in the Estuary and Gulf of St. Lawrence under winter conditions.

The marine chemistry of platinum group elements is poorly documented despite robust evidence of their widespread emissions and deposition around the globe. Here, we report the concentrations and discuss the geochemical behaviours of Ag, Pd and other trace and ultra-trace elements in the Estuary and Gulf of St. Lawrence (EGSL). We highlight the contrasting mixing behaviours of these elements, i.e., conservative (Cd, Re) vs. non-conservative (Ag, Pd), in samples collected during the winter and under ice-covered conditions. We ascribe the contrasting geochemical behaviour of these elements to their differential affinity for reactive surfaces carried into the estuary from the frozen watersheds. We also report an increase of the concentrations of Ag (up to 40 pmol L-1), Pd (up to 10 pmol L-1) and Pt (up to 0.4 pmol L-1) in the bottom and oxygen-depleted waters of the Gulf of St. Lawrence (GSL). A strong correlation between dissolved Pt concentrations and the stable carbon isotopic composition of the dissolved inorganic carbon (δ13C-DIC) suggests that the increased mobility of Pt may result from the aerobic mineralization of organic carbon or the oxidation of Pt-bearing organic complexes. Molar Pt/Pd ratios in the three water masses that compose the water column in the EGSL highlight a potential influence of anthropogenic sources near urban centers. The signature of continental end-members will be required to confirm the impacts of road traffic on the estuarine geochemistry of these elements.

Sample preparation - A crucial step to distinguish metallic and ionic platinum forms and their mobility in soil.

The study is focused on one of the technology-critical elements (TCEs), Pt in the context of distinguishing ionic from metallic forms and assessing sorption capacity of soil. Solid-liquid extraction, cross-comparison of the results of two determination techniques and two decomposition methods enable quantitative determination of the ionic form and, indirectly, NPs in soil and plants. Information about ionic form is obtained after sample digestion with conc. HNO3 and AdSV determination, and total Pt content is determined after digestion using mixture of conc. HNO3 and conc. HCl. The recovery of Pt was in the range 99-110 % for both forms. The mobility (0.43 mol L-1 HAc) of Pt-NPs and Pt (II) was below 1 % even in the presence of citrates (after 2 month incubation). The long-term sorption study indicated that Pt retention (both forms) in the organic soil is related to formation of organic complexes, and the equilibrium is achieved after 2 days. When the soil is enriched in Fe2O3, stronger sorption is observed up to 2 days for both Pt forms (the mobility is 9-14 pp. lower), to finally achieve similar sorption as without modification, reaching 89/90 % for incubation with DI water, and 81/85 % with citrates. The addition of biocarbon/biochar does not play an important role in immobilization of Pt (II) and Pt-NPs.

Occurrence of palladium and platinum in human scalp hair of adolescents living in urban and industrial sites.

Platinum group elements (PGEs) can be naturally found at very low concentrations in the Earth's crust. However, the increasing uses of PGEs in vehicle exhaust catalysts, in addition to some other applications (industry, jewelry, anticancer drugs) cause their anthropogenic emission and dispersion in the environment. The use of human hair samples analysis is considered a suitable biological indicator to assess human occupational and environmental exposure. It is an easily accessible material for individuals or population groups of non-invasive sampling. The aim of this study is a comparative analysis to investigate human hair content of Pd and Pt in adolescents, of both genders, residing near petrochemical plants of Augusta and Gela, in urban area of Palermo, and Lentini as control site (Sicily, Italy). A total of 108 samples were taken from school students (11-14 years old). Hair samples were cleaned, mineralized, and processed for analyses by inductively coupled plasma-mass spectrometry (ICP-MS). The samples from the industrial sites of Gela and Augusta do not have statistically significant differences between them for either Pd for Pt; however, they differ from the samples relating to the city of Palermo. Median Pd concentrations are higher than Pt in industrial sites and control site. In urban site the levels of both metals were comparable. The study does not reveal any statistically significant difference between Pd and Pt concentrations in female and male samples. The data confirm that the study areas are heavily affected by industrial and urban emissions of Pd and Pt, representing a potential hazard to the local population.

Laser ablation-inductively coupled plasma-mass spectrometry analysis reveals differences in chemotherapeutic drug distribution in surgically resected pleural mesothelioma.

AIMS: Pleural mesothelioma (PM) is a highly aggressive thoracic tumour with poor prognosis. Although reduced tissue drug accumulation is one of the key features of platinum (Pt) resistance, little is known about Pt distribution in human PM. METHODS: We assessed Pt levels of blood samples and surgically resected specimens from 25 PM patients who had received neoadjuvant Pt-based chemotherapy (CHT). Pt levels and tissue distributions were measured by laser ablation-inductively coupled plasma-mass spectrometry and correlated with clinicopathological features. RESULTS: In surgically resected PM specimens, mean Pt levels of nontumourous (fibrotic) areas were significantly higher (vs tumourous regions, P = 0.0031). No major heterogeneity of Pt distribution was seen within the tumourous areas. Pt levels correlated neither with the microvessel area nor with apoptosis rate in the tumourous or nontumourous regions. A significant positive correlation was found between serum and both full tissue section and tumourous area mean Pt levels (r = 0.532, P = 0.006, 95% confidence interval [95% CI] 0.161-0.771 and r = 0.415, P = 0.039, 95% CI 0.011-0.702, respectively). Furthermore, a significant negative correlation was detected between serum Pt concentrations and elapsed time from the last cycle of CHT (r = -0.474, P = 0.017, 95% CI -0.738--0.084). Serum Pt levels correlated negatively with overall survival (OS) (P = 0.029). CONCLUSIONS: There are major differences in drug distribution between tumourous and nontumourous areas of PM specimens. Serum Pt levels significantly correlate with full section and tumourous area average Pt levels, elapsed time from the last CHT cycle, and OS. Further studies investigating clinicopathological factors that modulate tissue Pt concentration and distribution are warranted.

Platinum Group Element distribution in water and marine biota from two impacted estuarine environments (Douro and Ave estuaries, Portugal).

Platinum Group Elements (PGEs) are contaminants of emerging environmental concern considering their continuous increasing use and subsequent release in the environment. While recent field studies provided PGE levels in seawater, scarce knowledge still exists regarding PGE contamination in marine organisms, especially for rhodium (Rh). Water, macroalgae and mussels were sampled along two representative urbanized estuarine systems and adjacent coastal areas (Douro and Ave estuaries, Portugal). Rhodium and platinum (Pt) concentrations were quantified through both stripping voltammetry and mass spectrometry in collected samples. Spatial mapping of PGE contamination was, to a certain extent, correlated with proxies of urban effluents. The use of Pt/Rh ratios reflected the dominant influence of PGE traffic emissions along the Douro and inputs from various sources (including industries) on the Ave Estuary. Macroalgae and mussels PGE concentrations reflected urban pressure, amplifying environmental signals, and supporting their relevant use as bioindicators of PGE contamination in estuarine/coastal systems.

Exposure to soluble platinum salts in precious metal refinery workers over a 17-year period.

BACKGROUND: Occupational exposure to soluble chlorinated platinum (Pt) salts, commonly called chloroplatinates, is a known cause of Pt salt sensitisation (PSS) and occupational asthma. We aimed to model inhalable soluble Pt salts exposure levels based on measurements in precious metal refineries for use in a retrospective cohort study on PSS. METHODS: Five platinum refineries located in the United Kingdom (3 sites), United States, and South Africa provided time weighted average inhalable soluble Pt salts exposure data, measured in 2,982 personal air samples over a 17-year period (2000-2016). We used a Bayesian hierarchical model to estimate geometric mean (GM) exposure levels for each refinery and job title over time. RESULTS: The GM of measured exposure levels over all facilities was 92 ng/m3 with a geometric standard deviation (GSD) of 9.07. Facility-specific GMs ranged from 48 ng/m3 (GSD 15.3) to 242 ng/m3 (GSD 5.99). Exposure modelling showed that soluble Pt salts exposure levels declined approximately 10% per year in two of the five facilities, but there were no clear time trends in the other facilities. A priori specified exposure groups captured most of the between-jobs differences, which helps to accurately predict exposures for jobs with no measurement data available. CONCLUSIONS: We applied exposure modelling to estimate time, refinery, and job-specific soluble Pt salts exposures. A significant annual decline in exposure levels was observed in two of the five participating facilities. Modelled exposure levels can be linked to individual workers' job history for exposure-response analysis of PSS in an epidemiological study.

Evaluation of long-term data on surface contamination by antineoplastic drugs in pharmacies.

PURPOSE: The handling of antineoplastic drugs represents an occupational health risk for employees in pharmacies. To minimize exposure and to evaluate cleaning efficacy, wipe sampling was used to analyze antineoplastic drugs on surfaces. In 2009, guidance values were suggested to facilitate the interpretation of results, leading to a decrease in surface contamination. The goal of this follow-up was to evaluate the time trend of surface contamination, to identify critical antineoplastic drugs and sampling locations and to reassess guidance values. METHODS: Platinum, 5-fluorouracil, cyclophosphamide, ifosfamide, gemcitabine, methotrexate, docetaxel and paclitaxel were analyzed in more than 17,000 wipe samples from 2000 to 2021. Statistical analysis was performed to describe and interpret the data. RESULTS: Surface contaminations were generally relatively low. The median concentration for most antineoplastic drugs was below the limit of detection except for platinum (0.3 pg/cm2). Only platinum and 5-fluorouracil showed decreasing levels over time. Most exceedances of guidance values were observed for platinum (26.9%), cyclophosphamide (18.5%) and gemcitabine (16.6%). The most affected wipe sampling locations were isolators (24.4%), storage areas (17.6%) and laminar flow hoods (16.6%). However, areas with no direct contact to antineoplastic drugs were also frequently contaminated (8.9%). CONCLUSION: Overall, the surface contaminations with antineoplastic drugs continue to decrease or were generally at a low level. Therefore, we adjusted guidance values according to the available data. The identification of critical sampling locations may help pharmacies to further improve cleaning procedure and reduce the risk of occupational exposure to antineoplastic drugs.

Novel Platinum-Nickel Composite Trap for Simultaneous and Direct Determination of Mercury and Cadmium in Soil and Its Mechanism Study.

In this work, following a metal-ceramic heater (MCH) as an electrothermal vaporizer (ETV), a novel composite Pt/Ni trap based on platinizing the foamed nickel was first fabricated to trap Hg and Cd simultaneously. So, a solid sampling Hg-Cd analyzer was developed to simultaneously detect trace Hg and Cd in soil samples, mainly consisting of an MCH, a composite Pt/Ni trap, and an atomic fluorescence spectrometer (AFS). This small-size MCH-ETV system only consumes 100 W for the complete vaporization of Hg and Cd in soil matrices. The Pt/Ni trap fulfills the complete trapping of Hg and Cd following the solid sampling MCH-ETV system and then fast releases them by heating. It was proved that trapped and released Hg and Cd by the Pt/Ni trap are atomic species using X-ray photoelectron spectroscopy (XPS) and other approaches; specially, the effective cotrapping of Hg and Cd might be due to forming alloys of Hg + Pt and Cd + Ni on the Pt/Ni trap. Under the optimized conditions, the method detection limits (LODs) of Hg and Cd reached 0.4 µg/kg and 0.04 µg/kg for a 20 mg sample size, the relative standard deviations (RSDs) were within 12% and 8% for soil samples, respectively, and the recoveries ranged from 96% to 105%, indicating favorable analytical sensitivity, precision, and accuracy. The whole analysis time can be controlled within 5 min without the soil digestion process. The proposed Hg-Cd analyzer is thus suitable for rapid detection of Hg and Cd in soil samples with advantages such as simplicity, green, and safety. Further, the proposed solid sampling ETV-composite trap method has a promising application potential in the field and rapid detection for multielements.

A pipette-adapted biosensor for Salmonella detection.

In-field screening of pathogenic bacteria is important for preventing food poisoning. Here, a portable pipette-adapted biosensor using magnetic grid separation and nanocatalyst signal amplification was elaboratively developed for rapid detection of Salmonella typhimurium. A common pipette was innovatively adapted with multiple functions to complete the whole bacterial detection procedure, including mixing, separation, catalysis, washing, detection, analysis and display. The target bacteria were effectively captured by the immune magnetic nanobeads and labeled with immune gold@platinum nanocatalysts through pipette-blowing mixing to form the nanobeads-bacteria-nanocatalyst complexes, which were separated against the magnetic grid separation tip under the magnetic field. The pressure change resulting from oxygen production due to mimicking catalysis of hydrogen peroxide by these nanocatalysts on the complexes was quantified through measuring the moving duration of the conductive liquid in the pipette for bacteria determination. Under optimal conditions, this biosensor could detect target bacteria in 90 min with low detection limit of 180 CFU/mL. This pipette-adapted biosensor is affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to end-users (ASSURED), and has the potential for in-field testing of foodborne pathogens to ensure food safety, especially in resource-constrained areas.

Indicator of Reduction in Soil (IRIS) devices: A review.

Documenting anaerobic conditions is critical for understanding soil processes, identifying hydric soils, delineating wetlands, and managing aquatic resources. Several techniques exist to evaluate the oxidation-reduction status of soils including platinum electrodes, chemical dyes, and analyses of porewater chemistry. Since 2002, Indicator of Reduction in Soils (IRIS) devices have proven a novel, reliable, and cost-effective technique to document anaerobic conditions. This technology involves the application of redox active Fe or Mn oxide based paints onto a durable substrate (e.g., Polyvinyl Chloride pipes or plastic films) which are inserted into the soil. If anaerobic conditions occur during deployment, some or all of the redox active paint will be depleted from the IRIS device surface via chemical reduction and the extent of paint removal can be quantified using a number of approaches. Over the last two decades, IRIS technology has evolved to improve the identification of anaerobic conditions in soils and provide a proxy measure of multiple soil biogeochemical processes (e.g., denitrification, elemental sorption, iron sulfide formation). This review paper provides an overview of developments in IRIS instrumental design and interpretation of results, describes current IRIS applications and benefits, and identifies potential future areas of IRIS device research.

Distribution of Platinum and Palladium between Dissolved, Nanoparticulate, and Microparticulate Fractions of Road Dust.

Ageing processes of vehicle catalytic converters inevitably lead to the release of Pt and Pd into the environment, road dust being the main sink. Though Pt and Pd are contained in catalytic converters in nanoparticulate metallic form, under environmental conditions, they can be transformed into toxic dissolved species. In the present work, the distribution of Pt and Pd between dissolved, nanoparticulate, and microparticulate fractions of Moscow road dust is assessed. The total concentrations of Pt and Pd in dust vary in the ranges 9-142 ng (mean 35) and 155-456 (mean 235) ng g-1, respectively. The nanoparticulate and dissolved species of Pt and Pd in dust were studied using single particle inductively coupled plasma mass spectrometry. The median sizes of nanoparticulate Pt and Pd were 7 and 13 nm, respectively. The nanoparticulate fraction of Pt and Pd in Moscow dust is only about 1.6-1.8%. The average contents of dissolved fraction of Pt and Pd are 10.4% and 4.1%, respectively. The major fractions of Pt and Pd (88-94%) in road dust are associated with microparticles. Although the microparticulate fractions of Pt and Pd are relatively stable, they may become dissolved under changing environmental conditions and, hence, transformed into toxic species.

The temporal distribution of platinum group elements (PGEs) in PM2.5.

In this paper, Changji, Xinjiang, northwest China, was selected as the study area, and platinum group elements (PGEs) in PM2.5 were quantified by ICP-MS using microwave digestion. The results indicated that the average concentrations (and range) of Rh, Pd, and Pt in PM2.5 were 0.21 (n.d. -1.41) ng/m3, 8.09 (n.d. -59.50) ng/m3, and 0.12 (n.d. -0.83) ng/m3, respectively. The concentration of Pd was significantly higher than Rh and Pt. Moreover, the seasonal variations of Rh and Pd were the same: highest in summer and lower in other seasons. However, the seasonal variation of Pt was opposite to that of Rh and Pd: highest in winter and lower in other seasons. Seasonal differences in emission sources of PGEs and the climatic characteristics of arid regions played important roles in the seasonal changes of PGEs. Rh and Pd had a common source and similar diurnal variation. The major influencing factors were traffic volume and meteorological conditions. The diurnal variation regularity of Pt was different from Rh and Pd. The superimposed effect of vehicle exhaust emissions and coal-fired emissions was the main reason why the diurnal variation of Pt was more complicated than those of Rh and Pd. The diurnal concentration of Pt varied with the seasons. It is caused by seasonal coal combustion and meteorological conditions.

[Review on the speciation analysis methods of platinum group metals in environmental media]. / çŽ¯å¢ƒä»‹è´¨ä¸­é“‚æ—é‡‘å±žå½¢æ€åˆ†æžæ–¹æ³•çš„ç ”ç©¶è¿›å±•.

Platinum group metals (PGMs) present a variety of forms in the environment, and analysis of speciation is essential for identifying their ecological risk. Here, we reviewed the methods for the morphological analysis of three major PGMs (platinum, palladium and rhodium) in the environment, including chemical sequential extraction, hyphenated techniques for instruments, computer simulations. We outlined the types, characteristics and applications of these methods, elaborated the weaknesses, and provided prospects for future development. Among them, chemical sequential extraction is universally applied in the morphological analysis of solid-phase samples, with diverse extraction conditions and procedures proposed in the current study. However, it has not been well standardized. The hyphenated techniques for instruments have significant advantages for the determination of elemental forms in solution, of which capillary electrophoresis system can separate similar substances with the same electrophoresis ability. Liquid chromatography systems have better performance in terms of separation capacity and detection limit. The computer simulations further expand the access to morphological analysis, enabling complex morphological calculations. It was proposed to combine multiple methods in the future to continuously improve the accuracy of analytical techniques by complementing and optimizing each other.

[Determination of platinum anticancer drugs in occupational settings by ICP-MS].

Objective: To establish an inductively coupled plasma mass spectrometry (ICP-MS) for platinum antineoplastic drugs in the environment. Methods: The platinum antineoplastic drugs in the environmental table were eluted by wiping and collecting pure water, and the supernatant was taken by centrifugation and inductively coupled plasma mass spectrometry for detection. Results: The concentration range of 0-8.0 µg/L was good, the correlation coefficient was 1.000, the detection limit was 0.0006 µg/L, the lower quantitative limit was 0.002 µg/L, the method precision was between 0.9%-1.3%, and the sample standard recovery rate was between 97.0%-98.5%. Conclusion: This method has low detection limit, high accuracy and precision, and simple sample pretreatment, which is suitable for the determination of platinum antineoplastic drugs in environmental tables.

Determination of Renal Distribution of Zinc, Copper, Iron, and Platinum in Mouse Kidney Using LA-ICP-MS.

The main dose-limiting side effect of cisplatin is nephrotoxicity. The utilization of cisplatin is an issue of balancing tumour toxicity versus platinum-induced nephrotoxicity. In this study, we focused on intraorgan distribution of common essential trace elements zinc, copper, and iron in healthy mouse kidneys and distribution of platinum after cisplatin treatment. Renal distribution in 12 nontreated Nu-Nu mice (males) was assessed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Furthermore, 9 Nu-Nu mice were treated with cisplatin. The order of elements concentration in kidneys was as follows: Fe > Zn > Cu. All three metals showed the higher concentrations at the cortex and medulla (28.60, 3.35, and 93.83 µg/g for Zn, Cu, and Fe, respectively) and lower concentration at the pelvis and the urinary tract (20.20, 1.93, and 62.48 µg/g for Zn, Cu, and Fe, respectively). No statistically significant difference between cortex and medulla was observed for these elements. After platinum treatment, the concentration of platinum in kidneys was enhanced more than 60-times, p < 0.001. Platinum significantly showed the highest accumulation in cortex (2.11 µg/g) with a gradient distribution. Platinum was less accumulated in medulla and pelvis than in cortex, and the lowest accumulation occurred in the urinary tract (1.13 µg/g). Image processing has been successfully utilized to colocalize metal distribution using LA-ICP-MS and histological samples images.

Platinum group elements contamination in soils: Review of the current state.

Platinum group elements (PGE: Ru, Rh, Pd, Os Ir, Pt) are rare metals with low abundance in the continental crust. The elements of the palladium subgroup of PGE (PPGE: Pt, Pd, Rh) have been exploited more and more over the last thirty years for their physicochemical properties such as high melting point, high resistance to corrosion, mechanical strength and ductility. This led to emerging environmental contamination in different media such as air, road dust, soil, sediment, vegetation, and snow. The aim of this review is to summarize the available data on soil contamination by PPGE and its potential environmental impact. In this paper, the environmental issue of PPGE is discussed with regard to their anthropogenic emission and fate, which includes speciation, possible transformations into bioavailable forms and toxicity. Soil contamination by PPGE is described taking into account urban and non-urban areas. The analytical determination process is also discussed.

Emerging contaminants (Rh, Pd, and Pt) in surface sediments from a Brazilian subtropical estuary influenced by anthropogenic activities.

The concentrations of Platinum (Pt), Rhodium (Rh) and Palladium (Pd) were evaluated from a highly impacted estuary in Brazil influenced by industrial pole, highway traffic and sewage outfall. The Santos-São Vicente region presents important economic activities derived from a largest harbor of Latin America and an industrial pole surrounded by intensive highway traffic. Values of Rh varied from 0.08 to 1.7 ng g-1 with highest values at stations impacted by domestic waste. Pt ranged from 0.15 to 40.3 ng g-1 with highest concentrations located close to the ferryboat traffic. Pd levels varied from 1.05 to 22.0 ng g-1 with values >5 ng g-1 in 50% of the stations. The spatial distribution of PGEs was not always directly associated with muddy sediments, because high PGE levels found even in sandy sediments. Pollution indexes, including anthropogenic factor (AF), geoaccumulation index (Igeo), Enrichment factor (EF), and Pollution Load Index (PLI) were used for evaluating contaminant potential. Based on EF, Igeo, and PLI, 50% of samples of the sediments from Santos-São Vicente Estuarine System (SSV) were classified with significant to strong PGE contamination. All stations on the Santos Channel (SC), São Vicente Channel (SVC) and Bertioga Channel (BC) had AF higher than 80% in at least one of PGE elements, as showed in station 2A, which presented AF <50% for Rh and Pd and 86% for Pt. Despite high anthropogenic enrichment, no correlations among PGE elements were observed in surface sediments. Only two stations presented Pd/Pt, Pt/Rh, and Pd/Rh typical ratios of auto catalyst (st. 14 and Piaçaguera) both located in the vicinity of highways. This could be due to the PGE deposition process in road dust, soil, and water as well as the biogeochemical cycling of PGEs involving organic metallic and inorganic complexes formed in the estuarine and seawaters.

Droplet-Splitting Microchip Online Coupled with Time-Resolved ICPMS for Analysis of Released Fe and Pt in Single Cells Treated with FePt Nanoparticles.

The intracellular release of Fe/Pt ions from FePt nanoparticles (NPs) in single cells is highly critical to elucidate the potential cytotoxicity or potential cell protection mechanism of FePt NPs. For the first time, the quantitative analysis of Fe/Pt released from FePt-Cys NPs in single cells was achieved by a droplet-splitting microchip coupled online to inductively coupled plasma mass spectrometry detection. The droplet-splitting chip integrates droplet generation, cell lysis, and droplet-splitting units. The quantification of released Fe/Pt was achieved via measuring standard Fe/Pt ionic solutions. For the determination of total Fe/Pt in single cells, the same microchip with different operation modes (total-mode) was used, and the quantification of total Fe/Pt was achieved with FePt NPs as the standard. The developed method with two analysis modes was applied to study the decomposition behavior of FePt-Cys NPs in single cells, and the results indicated that the percentages of the cells absorbing/decomposing FePt-Cys NPs increased with the incubation time. Almost all cells absorbed FePt-Cys NPs after 6 h, while only about 60% cells decomposed FePt-Cys NPs after 6 h and almost all cells decomposed FePt-Cys NPs after 18 h. Besides, the released Fe content was lower than its endogenous content in cells and the release rate of Pt was higher than that of Fe, providing a possibility that the released Pt may contribute more to cytotoxicity. The developed system enabled fractionation of Fe/Pt in single cells treated with FePt NPs with high accuracy, easy operation, and high throughput and showed a great potential for elemental speciation at the single-cell level.

The role of fish helminth parasites in monitoring metal pollution in aquatic ecosystems: a case study in the world's most productive platinum mining region.

Due to the increasing consumption of platinum (Pt), especially in automobile exhaust catalysts, environmental concentrations of Pt are of emerging concern worldwide. Limited information exists on environmental concentrations, particularly in Pt mining regions, while South Africa is the world's main supplier of Pt. Moreover, other metals are also released as by-products of Pt mining, which might also cause environmental concern. Certain fish parasite taxa have the ability to accumulate metals orders of magnitude higher than their hosts and can be used to reliably detect metals with naturally low abundance. Studies on Pt accumulation in parasite-host systems are limited. Therefore, the aims of the present study were (1) to determine the accumulation of a variety of metals (cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), platinum (Pt), and zinc (Zn)) in helminth fish parasites compared with their hosts from a reference site and an impoundment impacted by Pt mining activities; (2) to assess whether there is a difference between bioaccumulation of metals in infected and uninfected hosts, as well as between hosts with different infection intensities; and (3) to compare the biomarker responses (acetylcholine esterase activity (AChE), metallothionein content (MT), catalase activity (CAT), reduced glutathione content (GSH), malondialdehyde content (MDA), protein carbonyls induction (PC), superoxide dismutase activity (SOD), and cellular energy allocation (CEA)) between infected and uninfected hosts. The cestode Atractolytocestus huronensis accumulated significantly higher concentrations of Cr, Ni, and Pt than their host Cyprinus carpio, while the nematode Contracaecum sp. accumulated significantly higher concentrations of Pt and Zn than their host Clarias gariepinus. Infected fish showed lower metal concentrations compared to uninfected fish, while the parasites had no significant effects on their hosts' biomarker responses. The parasites demonstrated the bioavailability of metals derived from Pt mining activities and their ability to resist its toxic effects. Thus, these parasites are promising sensitive accumulation indicators for Cr, Ni, Pb, and Pt contaminations from Pt mining activities.

Selective Gold Recovery from Homogenous Aqueous Solutions Containing Gold and Platinum Ions by Aromatic Amino Acid-Containing Peptides.

There is increasing interest in the development of noble metal separation/recovery processes, especially for applications to "urban mining". Common separation/recovery processes for noble metals use a solvent (liquid-liquid) extraction technique in hydrometallurgy. However, these processes are time-consuming and not environmentally friendly, because they use organic solvents for sequential metal ion extractions. Electrowinning is an alternative approach for selective metal precipitation that involves controlling the redox potentials of electrodes but requires specialized equipment and generates hydrogen as a byproduct at the cathode surface under dilute conditions. In the present study, we investigated selective gold recovery from a homogenous aqueous solution containing a mixture of dilute HAuCl4 and H2PtCl6 (5.0 × 10-5 M each) and aromatic amino acid-containing peptides (2.0 × 10-4 M each). Gold selectivity was determined by analyzing the compositions of the solids and supernatants obtained from the reaction mixtures. A much higher gold selectivity (gold/platinum (Au/Pt) atomic ratio = 7.5) was obtained using an anthracene-containing peptide compared to peptides containing one or two naphthalene ring(s). Our proposed approach is applicable to the sequential separation of several noble metal ions, such as Au, palladium (Pd), Pt, iridium (Ir) and rhodium (Rh), and simply requires developing aromatics suitable for each noble metal of interest.