High Concentrations Of Cu Research Articles

OsCOPT7 is a copper exporter at the tonoplast and endoplasmic reticulum and controls Cu translocation to the shoots and grain of rice.

Copper (Cu) is an essential micronutrient for all living organisms but is also highly toxic in excess. Cellular homoeostasis of Cu is maintained by various transporters and metallochaperones. Here, we investigated the biological function of OsCOPT7, a member of the copper transporters (COPT) family, in Cu homoeostasis in rice. OsCOPT7 was mainly expressed in the roots and the expression was upregulated by Cu deficiency. OsCOPT7 was localized at the tonoplast and the endoplasmic reticulum. Knockout of OsCOPT7 increased Cu accumulation in the roots but decreased Cu concentrations in the shoots and grain. The knockout mutants contained higher concentrations of Cu in the roots cell sap but markedly lower concentrations of Cu in the xylem sap than wild-type plants. Seed setting and grain yield were reduced significantly in the knockout mutants grown in a low Cu soil. Knockout mutants were more tolerant to Cu toxicity. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that OsCOPT7 interacts physically with the rice Cu chaperone antioxidant protein 1 (OsATX1). Taken together, our results indicate that OsCOPT7 is a specific Cu transporter functioning to export Cu from the vacuoles and the ER and plays an important role in controlling the root-to-shoot Cu translocation in rice.

Lead and Copper Removal from Mine Tailings Using Lycium chilense and Haplopappus foliosus

In Chile, the budget for managing environmental liabilities such as abandoned tailings impoundments is limited. Using native and endemic plant species to remove heavy metals from tailings represents a low-cost alternative. Ex situ phytoremediation experiments were conducted over a period of seven months. The endemic species Lycium chilense and native species Haplopappus foliosus were used to remove copper and lead from mine tailings. The results indicate that both species can concentrate levels of Cu and Pb higher than the toxicity threshold in the roots and aerial parts, and present high removal efficiency for Cu higher than 50%. In both species, the concentrations of the target elements are higher in the roots than in the aerial parts. Haplopappus foliosus presents the best performance, accumulating higher concentrations of Cu and Pb than Lycium chilense, and presenting a bioconcentration of over one for Cu.

Performance and mechanism of amphiphilic polymeric chelator for enhanced removal of high concentrations of Cu(II) from wastewater.

An amphiphilic polymeric chelator (APC16-g-SX) grafted with sodium xanthate (SX) groups was successfully prepared for the efficient removal of high concentrations of Cu(II) from wastewater. The ordinary polymeric chelator (PAM-g-SX) based on linear polyacrylamide (PAM) was also prepared for comparative studies. The polymeric chelators were characterized by Fourier transform infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance (13C-NMR), gel permeation chromatography (GPC), elemental analyzer, and scanning electron microscope (SEM). The chelating performance of these polymeric chelators was investigated, and the mechanism of APC16-g-SX for enhanced removal of Cu(II) from wastewater was proposed based on fluorescence spectroscopy, cryo-scanning electron microscope (Cryo-SEM), energy-dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS) tests. The results show that as the initial Cu(II) concentration in the wastewater increases, APC16-g-SX shows more excellent chelating performance than ordinary PAM-g-SX. For the wastewater with an initial Cu(II) concentration of 200mg/L, the removal rate of Cu(II) was 99.82% and 89.34% for both 500mg/L APC16-g-SX and PAM-g-SX, respectively. The pH of the system has a very great influence on the chelating performance of the polymeric chelators, and the increase in pH of the system helps to improve the chelating performance. The results of EDS and XPS tests also show that N, O, and S atoms in APC16-g-SX were involved in the chelation of Cu(II). The mechanism of enhanced removal of Cu(II) by APC16-g-SX can be attributed to the spatial network structure constructed by the self-association of hydrophobic groups that enhances the utilization of chelation sites.

The influence of the environmental factors on the accumulation patterns of toxic elements in Plantago lanceolata sampled in the area under strong anthropopressure

The study aims to explore the environmental factors which activate accumulation abilities of Plantago lanceolata in the research area under strong anthropopressure resulting from the long-term pollution originating from copper mining-metallurgical activities in Southeastern Europe. Sampling was performed at the most endangered sites regarding its proximity to the major and/or secondary pollution sources, as well at the control site. The content of toxic elements (Al, Cu, Fe, Mn, Ni, Pb and Zn) was determined in the roots, leaves, stalks and flowers of P. lanceolata. The anthropogenic origin of environmental contamination was denoted through the high concentrations of Cu, Pb and Zn in the leaves of P. lanceolata, reaching toxic levels, combined with the enrichment of plant parts (Enrichment factor >2), especially with Cu (as well as with Al, Fe, Ni and Zn) in samples from the immediate proximity to the copper smelter or at the prevailing wind directions. Biomonitoring potential, assessed through the correlations between toxic element content, as well as the values of Enrichment factor, was indicated for roots (in the case of Cu), all the aboveground plant parts (Fe) and stalks (Zn). The results have shown that the contents of toxic elements in plant parts as well as phytoremediation of P. lanceolata were dependent on soil element content, soil physico-chemical properties and soil enzyme activities, which were regarded as the main environmental drivers affecting phytoremediation ability. The analysis of biological factors (bioconcentration, translocation and bioaccumulation factor) indicated exclusion strategy and possible usage of P. lanceolata in phytostabilization of Zn. The results indicated that the study area is 'environmental hotspot' with potential threat to human health due to the high levels of bioaccumulation of the investigated toxic elements in P. lanceolata parts.

Geochemical Characteristics of Seabed Sediments in the Xunmei Hydrothermal Field (26°S), Mid-Atlantic Ridge: Implications for Hydrothermal Activity

The compositions of metalliferous sediments associated with hydrothermal vents can provide key geochemical data for locating seafloor sulfides. In this study, we present the geochemistry of seabed sediments from the Xunmei hydrothermal field (HF) in the South Mid-Atlantic Ridge (SMAR). The results indicate that the sediments are mainly composed of pelagic material (biogenic calcium components), basaltic debris, iron-manganese oxides, and hydrothermal components. The sediments are significantly enriched in Cu, Zn, Fe, and Co deriving from hydrothermal fluids, as well as Mn, V, Mo, U, and P, which are primarily scavenged from seawater. The northeastern Xunmei has the highest concentrations of Cu and Zn, while the northeastern, northern, and southern regions are characterized by great inputs of Fe. Manganese and Mo are mainly enriched in the western and southern parts and show a strong positive correlation, indicating that Mo is mainly scavenged by Mn oxides. Uranium, P, and Fe exhibit strong positive correlations, suggesting that they coprecipitate with Fe from hydrothermal plumes. Vanadium and Co are introduced into sediments in different ways: V is scavenged and coprecipitated by hydrothermal plumes, and Co is derived from sulfide debris. Based on the contents of Cu and Zn and Cu/Fe (0.159), Zn/Fe (0.158), and Fe/Mn (1440) ratios, it can be inferred that a high-temperature hydrothermal vent existed in northeastern Xunmei. In combination with the distribution patterns of the above elements, the hydrothermal vents in the southern part ceased erupting after a short period of activity. In addition, the high Mn anomaly and the high U/Fe ratios at the boundaries of the investigated area indicate the presence of a relatively oxidized environment in southwestern Xunmei.

Bioaccessibility-corrected probabilistic health risk assessment of dietary metal(loid) exposure in six major food groups in children from Northwest China

Dietary exposure to heavy metals and metalloids [metal(loid)s] deserves increased attention; however, there is a lack of a comprehensive understanding of the risks of dietary exposure from multi-type food intake and multi-metal(loid) exposure using a bioaccessibility-corrected method. Here, we determined the concentration and bioaccessibility of six toxic metal(loid)s in six major food groups in an industrial city with intensive smelting activity. By incorporating children’s dietary patterns, the probability distribution of health risks from dietary metal(loid)s exposure was assessed. Marked differences were observed in the dietary exposure characteristics within metal(loid)s and major food groups. Cereal and vegetables were the major food groups local children intake. Cereals, meat, beans, and aquatic products had the highest concentrations of Cu and Cd, Pb and Cr, Ni, and As, respectively. Generally, meat, eggs, and aquatic products exhibited higher bioaccessibility than cereals, beans, and vegetables. The bioaccessibility of metal(loid)s decreased in the following order: Pb > Cr > Cu > Ni > As > Cd. For non-carcinogenic risks, the average hazard index was 7.3, with 99.6% exceeding acceptable levels. Arsenic was the dominant risk element and aquatic product was the main risk source. The aggregated carcinogenic risk was 3.4 × 10–3, with Cr the major risk contributor and cereals and meat the dominant food sources. The findings demonstrated that (1) the metal(loid) dietary exposure risk of children from areas with intensive smelting activities should be taken seriously, and (2) it is necessary to identify the specific food category and metal(loid) based on a comprehensive analysis of the metal(loid) concentration and bioaccessibility, and dietary habits of the population to effectively reduce risk.

Trace elements in the river waters of the coast of the Tatar Strait (eastern macroslope of the northern Sikhote-Alin)

The river basins of the northern Sikhote-Alin are unique, since most of the rivers are spawning for Pacific salmon, and the eastern slope of the Sikhote-Alin is a promising area for the construction of fish hatcheries. At the same time, in recent years, the anthropogenic impact on the territory has been increasing, mainly in the mouth areas of many small rivers flowing into the Tatar Strait. In 2010–2017 hydrochemical studies of the surface waters of the coast of the Tatar Strait were carried out. On the basis of the obtained results, a characteristic of the microelement composition of river and lake waters in the zone of mixing with sea water is given. Analysis of the data obtained by inductively coupled plasma mass spectrometry on an ICP-MS Agilent 7500cx instrument made it possible to estimate the content of trace elements in the water of coastal rivers. The regional factors of the formation of the microelement composition of river waters, determined by the geological features of the catchment structure, are revealed. The elevated geochemical background determines the high concentrations of Cu, Zn, in some cases Cd, Co, Ni, As, Mn in river water. The influence of geochemical features and landscape structure of river catchments on the spatial variation and temporal variability of concentrations is shown. The influence of thermal springs and outflows of formation and fissure groundwater on the increase in the concentrations of individual elements V, Mo, Ba in the rivers of the Botchi and Koppi interfluve was noted. The thermal waters of the Tumninskoe geothermal field with a high content of As, Fe, Mn, Mo, and Cr caused a local increase in the As content in water bodies in the lower reaches of the Tumnin River. Interannual seasonal differences in the runoff of microelements depending on the degree of moisture in the catchment area were noted. Taking into account that the chemical composition of the rivers along the coast of the Tatar Strait is formed mainly in a remote and underdeveloped territory and is determined by natural processes, the obtained concentration values can be considered background.

Studies on bioaccumulation patterns, biochemical and genotoxic effects of copper on freshwater fish, Catla catla: an in vivo analysis.

During present study, the copper (Cu) mediated oxidative stress was measured that induced DNA damage by concentrating in the tissues of fish, Catla catla (14.45±1.24g; 84.68±1.45mm) (Hamilton,1822). Fish fingerlings were retained in 5 groups for 14, 28, 42, 56, 70 and 84 days of the exposure period. They were treated with 2/3, 1/3, 1/4 and 1/5 (T1-T4) of 96h lethal concentration of copper. Controls were run along with all the treatments for the same durations. A significant (p < 0.05) dose and time dependent concentration of Cu was observed in the gills, liver, kidney, muscles, and brain of C. catla. Among organs, the liver showed a significantly higher concentration of Cu followed by gills, kidney, brain, and muscles. Copper accumulation in these organs caused a significant variation in the activities of enzymes viz. superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). The SOD activity varied significantly in response to the exposure time of Cu as 56 > 70 > 42 > 84 > 28 > 14 days while CAT activity exhibited an inverse relationship with the increase in Cu concentration. POD activity showed a significant rise with an increase in Cu exposure duration. Comet assay exhibited significant DNA damage in the peripheral erythrocytes of Cu exposed C. catla. Among four exposure concentrations, 2/3rd of LC50 (T1) caused significantly higher damage to the nuclei compared to control. Increased POD and SOD activity, as well as a decrease in CAT activity in response to Cu, demonstrates the involvement of a protective mechanism against reactive oxygen species (ROS), whereas increased ROS resulted in higher DNA damage. These above-mentioned molecular markers can be efficiently used for the biomonitoring of aquatic environments and conservation of edible fish fauna.

Field determination and ecological health risk assessment of trace metals in typical mariculture area of China

Field determination of dissolved trace metals (Cu, Pb and Cd) by using automated electrochemical system had been done in three typical mariculture areas of Yellow Sea (YS), East China Sea (ECS) and South China Sea (SCS) in China. Higher concentrations of Cu and Pb were found in ECS while the Cd concentration showed a decreasing trend from north to south of China. The metal distribution and ecological health risk assessments were also conducted. Cu and Pb in the YS and Cu in SCS were moderately contaminated. ECS had considerable Cu contamination and very high Pb contamination. Compared with other coastal areas, mariculture affected the concentration and spatial distribution of trace metals, but it was not a necessarily dominant factor. Overall, the results contribute to the further development of field and on-board metal detection technology and lay a foundation for the realization of field ecological health risk assessments of mariculture waters.

Biofertilizers from wastewater treatment as a potential source of mineral nutrients for growth of amaranth plants.

Exploring alternative fertilizers is crucial in agriculture due to the cost and environmental impact of inorganic options. This study investigated the potential of sewage-derived biofertilizers on the growth and physiology of Amaranthus cruentus plants. Various treatments were compared, including control treatments with inorganic fertilizer and treatments with biofertilizers composed of microalgae, biosolids and reclaimed water. The following traits were investigated: photosynthetic pigments, gas exchange, growth, and leaf nutrient concentrations. The results showed that the concentrations of N, P, Cu, Fe Zn and Na nutrients, in the dry microalgae and biosolids, were quite high for the needs of the plants. The wet microalgae presented high concentration of Cu, Fe and Zn nutrients while reclaimed water contained high concentration of N, K, Ca and S. Na and Zn nutrients increased in the leaf of plants treated with dry microalgae and biosolid, respectively. At the beginning of the flowering phase, total chlorophyll and carotenoids contents were lower for plants grown with wet microalgae while for plants grown with higher doses of biosolid or reclaimed water total chlorophyll was increased, and carotenoids were not affected. Lower photosynthetic pigments under wet microalgae resulted in lower photosynthetic rates. On the other hand, amendments with dry microalgae and biosolid increased photosynthetic rates with the biosolid being the most effective. Higher applications of biosolid, wet and dry microalgae produced a considerable increase in shoot biomass of amaranth, with the dry microalgae being the most effective. Additionally, reclaimed water obtained after tertiary treatment of sewage with microalgae and biosolids applied alone showed promising effects on plant growth. Overall, these findings suggest that organic fertilizers derived from sewage treatment have the potential to enhance plant growth and contribute to sustainable agricultural practices.

Proteomic Study of Broiler Plasma Supplemented with Different Levels of Copper and Manganese from Different Sources.

The aim of the present study was to evaluate the differential expression of plasma proteins in broiler chickens supplemented with different sources (sulfates and hydroxychlorides) and levels of copper (15 and 150 mg kg-1) and manganese (80 and 120 mg kg-1). For this, plasma samples from 40 broiler chickens were used, divided into four experimental groups: S15-80 (15 ppm CuSO4 and 80 ppm MnSO4), S150-120 (150 ppm CuSO4 and 120 ppm MnSO4), H15-80 (15 ppm Cu(OH)Cl and 80 ppm Mn(OH)Cl), and H150-120 (150 ppm Cu(OH)Cl and 120 ppm Mn(OH)Cl). From plasma samples obtained from each bird from the same treatment, four pools were made considering 10 birds per group. Plasma proteome fractionation was performed by 2D-PAGE. Concentrations of the studied minerals were also evaluated in both plasma and protein pellet samples. A higher concentration of Cu and Mn was observed in the plasma and protein pellets of groups that received higher mineral supplementation levels compared to those receiving lower levels. Mn concentrations were higher in plasma and protein pellets of the hydroxychloride-supplemented groups than the sulfate-supplemented groups. Analysis of the gels revealed a total of 40 differentially expressed spots among the four treatments. Supplementation with different sources of minerals, particularly at higher levels, resulted in changes in protein regulation, suggesting a potential imbalance in homeostasis.

Examination of interactions between heavy metals and benzotriazoles in rainwater runoff and snowmelt in an urban catchment in Poland

Heavy metals (HMs) are toxic pollutants that can accumulate and harm human health and the environment. Monitoring their concentration in water is an essential tool for evaluating the quality and safety of this vital resource. The aims of this study were (i) to characterize HMs contamination in rainwater runoff and snowmelt, identify likely sources and compliance with regulations and guidelines, and (ii) to conduct a preliminary assessment regarding the potential link between the occurrence of HMs and benzotriazoles based on a previous experiment. This study investigates the concentration of six HMs (cadmium, lead, nickel, chromium, copper, and zinc) in rainwater runoff and snowmelt samples collected in twelve Białystok locations in northeastern Poland. The highest concentration of Cu (517.5 μg/L) was identified in snowmelt from the city's ring road, with heavy vehicle traffic, and near an industrial area. A 4-lane asphalt street near the city center exhibited the highest concentrations of Pb (91.1 μg/L) and Ni (64.6 μg/L) for snowmelt and also for Cd (1.37 μg/L) and Ni (27.3 μg/L) in rainwater runoff. A snowmelt sample from a pedestrian-only area in the city center presented the highest Zn concentration (3672.2 μg/L). Considerable contents of Cr (353.2 μg/L) were found in snowmelt near an industrial and warehousing area. Snowmelt presented higher HMs concentrations than rainwater runoff. Our results indicate that most benzotriazoles and heavy metals occur independently. The analysis of the winds and the tendency of HMs to travel with dust particles suggest that specific contaminants might have originated in Belarus, a neighboring territory of Białystok.

A study on wheat grain zinc, iron, copper, and manganese concentrations and their relationship with grain yield in major wheat production areas of Iran

Iran is a country with different soils and climatic zones that affect the nutrient concentration in the produced wheat. Since wheat is one major component of Iranian diet, this survey was performed to investigate the concentration of micronutrients including copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) in wheat grains of Iran. For this purpose, a total of 1876 grain samples were collected from the wheat grown lands of Iran and analyzed for the micronutrients. Results revealed that the grain yields were found 5.50 and 2.02 ton ha−1 for irrigated and rainfed wheat, respectively. The average concentration of Zn, Fe, Cu, and Mn in the wheat was 26, 32.76, 34.7, and 5.94 mg kg−1 respectively. The spatial distribution of Zn, Fe, and Mn showed that the wheat produced in the south and southwestern, east and southwestern, and east were more enriched, respectively. While, the wheat produced in the central, south, and southwestern areas contained a higher concentration of Cu. Moreover, results showed that the average concentration of Zn (26 mg kg−1) and Fe (32.76 mg kg−1) was lower than the recommended concentrations for human health (i.e. Zn = 41 mg kg−1; Fe = 57 mg kg−1), which indicates a deficiency of these elements in the wheat grains. Due to the calcareous nature of the soils of Iran, alkaline pH, and low amount of organic matter, the bioavailability of nutrients are low and deficiency symptoms are revealed. Moreover, by increasing grain yield the concentration of grain elements decreases, which shows the effect of new varieties on intensifying the nutrient deficiency. The present study revealed the nutritional status of wheat grown in Iran and confirmed deficiency of Fe and Zn. This study provided information to the decision-makers to overcome this problem by employing proper strategies such as fortification and enrichment.

Geochemical, mineralogical, and geophysical methods to establish the geoenvironmental characteristics of the King River delta, Queenstown, Western Tasmania

Throughout most of the 20th century, the Mount Lyell Mining and Railway company discharged tailings from the Mount Lyell mine into the Queen River. Tailings migrated downstream of the King River and deposited on riverbanks, the riverbeds and in the King River delta in Macquarie Harbour. This research combines mineralogical, geochemical, and geophysical techniques to characterise the King River delta and to constrain the volume of mine tailings on the King River delta. For this purpose, 25 trenches were excavated across the delta with 145 sediments samples and 20 water samples collected.Tailings in the delta are abundant in quartz (average 50 wt %), muscovite (average 16 wt %), chlorite (mean 11 wt %), pyrite (average 4 wt %), Fe-oxyhydroxides such as goethite (average 0.8 wt %), hematite (average 0.4 wt % and ferrihydrite (average 0.2 wt %), jarosite (average 0.8 wt %) and chalcopyrite (average 0.1 wt %). Sediments are dominated by Fe (average 77,468 ppm) and include high concentrations of Cu (average 1425 ppm) and trace elements such as Co (average 350 ppm). Chalcopyrite is the primary Cu mineral whereas pyrite is the main mineral host for Co. Geoenvironmental tests show tailings in the delta have acid-forming potential, as validated by pore water analyses with pH between 3.1 and 6.3. These conditions enable metal dissolution, with high contents of dissolved heavy metals, especially Fe, Cu, Co and Zn, detected in the pore waters.Apparent resistivity and shear wave profiles suggest the base of tailings is located at depths of 3–5 m. Low resistivity (i.e., <2 Ωm) indicate a saltwater intrusion into likely natural sediments below the tailings, whereas resistivity values between approximately 5 to 12 Ωm, below 15 m depth, suggests a transition to bedrock. The volume of tailings is estimated at ∼14.0 Mt and concentrations of Cu and Co imply that reprocessing of this material could be a feasible option with significant economic and environmental benefits.

The arbuscular mycorrhizal fungus Rhizophagus irregularis uses the copper exporting ATPase RiCRD1 as a major strategy for copper detoxification

Arbuscular mycorrhizal (AM) fungi establish a mutualistic symbiosis with most land plants. AM fungi regulate plant copper (Cu) acquisition both in Cu deficient and polluted soils. Here, we report characterization of RiCRD1, a Rhizophagus irregularis gene putatively encoding a Cu transporting ATPase. Based on its sequence analysis, RiCRD1 was identified as a plasma membrane Cu + efflux protein of the P1B1-ATPase subfamily. As revealed by heterologous complementation assays in yeast, RiCRD1 encodes a functional protein capable of conferring increased tolerance against Cu. In the extraradical mycelium, RiCRD1 expression was highly up-regulated in response to high concentrations of Cu in the medium. Comparison of the expression patterns of different players of metal tolerance in R. irregularis under high Cu levels suggests that this fungus could mainly use a metal efflux based-strategy to cope with Cu toxicity. RiCRD1 was also expressed in the intraradical fungal structures and, more specifically, in the arbuscules, which suggests a role for RiCRD1 in Cu release from the fungus to the symbiotic interface. Overall, our results show that RiCRD1 encodes a protein which could have a pivotal dual role in Cu homeostasis in R. irregularis, playing a role in Cu detoxification in the extraradical mycelium and in Cu transfer to the apoplast of the symbiotic interface in the arbuscules.

Assessing the effects of single and binary exposures of copper and lead on Mytilus galloprovincialis: Physiological and genotoxic approaches

It is becoming increasingly recognised that contaminants are not isolated in their threats to the aquatic environment, with recent shifts towards studying the effects of chemical mixtures. In this study, adult marine mussels (Mytilus galloprovincialis) were exposed to two aqueous concentrations of the essential trace metal, Cu (5 and 32 μg L−1), and the non-essential metal, Pb (5 and 25 μg L−1), both individually and in binary mixtures. After a 14-day exposure, metal accumulation was determined in the digestive gland, gill and mantle tissues by inductively coupled plasma-mass spectrometry following acid digestion, and a number of biochemical, neurotoxic and physiological markers were assessed. These included measurements of DNA damage using comet assay, total glutathione concentration, acetylcholinesterase (AChE) activity and clearance rate. Metal accumulation was greater in the digestive gland and gill than in the mantle, and based on computed free ion concentrations, was greater for Pb than for Cu. Copper exhibited an inhibitory effect on Pb accumulation but Pb did not appear to affect Cu accumulation. Comet assay results revealed DNA damage (i.e., genotoxic effects) in all treatments but differences between the exposures were not significant (p > 0.05), and there were no significant differences in AChE activities between treatments. The most distinctive impacts were a reduction in clearance rate resulting from the higher concentration of Cu, with and without Pb, and an increase in glutathione in the gill resulting from the higher concentration of Cu without Pb. Multivariate analysis facilitated the development of a conceptual model based on the current findings and previously published data on the toxicity and intracellular behaviour of Cu and Pb that will assist in the advancement of regulations and guidelines regarding multiple metal contaminants in the environment.

Comparative Study on the Corrosion Behavior of Materials in Heat Recovery Steam Generators for Combined Cycle Power Plant, Based on Sulfuric Acid Concentrations: Carbon Steels vs. Duplex Stainless Steel (UNS S32205)

This study examined the effects of sulfuric acid concentrations on the corrosion behaviors of three types of commercial steels, conventional carbon steel (SA192), sulfuric acid dew resistant steel (S-TEN), and duplex stainless steel (S32205), considered to be potential materials for the heat recovery steam generator (HRSG) in combined cycle power plants. Based on the results of electrochemical polarization, immersion and wet-dry cycle tests, when exposed to a high sulfuric acid concentration (50%), SA192 and S-TEN exhibited higher corrosion resistance than S32205, which was due to the formation of a stable FeSO4 scale on the carbon steel materials. With prolonged exposure, S-TEN with slightly higher concentrations of Cu and Sb showed lower weight loss than SA192. Conversely, when subjected to low sulfuric acid concentrations (5 and 10%), S32205 exhibited passivation behavior, and showed significantly superior corrosion resistance (i.e., much smaller weight loss) than the other two steel samples. The examination of localized corrosion damages through cross-section observation using a scanning electron microscope revealed also that S32205 suffered less damages from the wet-dry cycling. The long-term superior corrosion resistance of duplex stainless steel in low sulfuric acid concentrations, compared to carbon steel and sulfuric acid due resistant steel, make it a promising candidate material for the HRSG in combined cycle power plants.

Trophic transfer and biomagnification of four heavy metals in freshwater food web: a case study of Zhangze Lake

ABSTRACT Heavy metals are a subject of widespread concern because of their persistence, potential toxicity, and accumulation in biological tissues. However, their biomagnification in food webs is still controversial and has not been studied in detail especially in freshwater ecosystems. This study investigated the trophic transfer and biomagnification of four heavy metals (Cu, Cd, Pb, and Hg) within the food web of the freshwater Lake Zhangze. The study showed that the trophic levels of aquatic consumers in the lake ranged from 2.00–4.53. The presence of Hg in sediments posed a strong ecological risk, and the integrated ecological risk was spatially reduced from the front of the dam to the tail of the reservoir. Planktivorous fish exhibited higher concentrations of Cu, Cd and Hg compared to other fish consumers. Heavy metals showed distinct bioaccumulation patterns within the food web, with Cu biomagnification primarily occurred at lower trophic levels, whereas Hg demonstrated biomagnification trends throughout the food web, while Cd and Pb rarely biomagnified within the food chain. Cu, Cd and Pb levels were effectively biodiluted with increasing biological trophic levels, whereas Hg levels increased with increasing trophic levels.

Middle Devonian Evandale porphyry Cu-Mo (Au) deposit, southwestern New Brunswick, Canada: Analysis of petrogenesis to potential as a source for distal intrusion-related epithermal gold mineralization

The 391.2 ± 3.2 Ma (U-Pb on zircon) Evandale Granodiorite of southwestern New Brunswick is quite a unique intrusive rock in the southern part of the northeastern Appalachians. This research examines the relationship between the porphyry Cu-Mo-(Au) and epithermal systems with Evandale Granodiorite and environs. This Middle Devonian multi-phase I-type granite intrudes along the northern boundary of the deformed Silurian sedimentary and mafic volcanic rocks of the Mascarene Basin. This granitoid is identified as an oxidized I-type system with adakitic geochemical signatures and associated porphyry Cu-Mo-(Au) mineralization, possibly linked to slab failure sourced from decompression melting of the lower crust caused by post-collisional uplift, similar to the Magaguadavic Granite to the southwest. The Evandale adakitic intrusion is divided into two phases that consist of (1) a calc-alkalic coarser phase ranging from medium- to coarse-grained, seriate to porphyritic granodiorite to monzogranite with metaluminous to peraluminous features, and (2) the later stage alkali-calcic fine-grained (to aplitic) locally porphyritic phase ranging from a monzogranite to syeno-granite with peraluminous characteristics. The primary mineralogy of the intrusive rocks consists of K-feldspar + albite + plagioclase + quartz + biotite + hornblende + apatite ± muscovite ± zircon, along with several alteration phases, such as biotite, chlorite, sericite, and calcite. Geochemical analyses (using INAA, ICP-MS, and XRF) indicate that both phases of the Evandale granodiorite show a high concentration of Cu (108 ppm) and Au (33 ppb) associated with the presence of pyrite, chalcopyrite, and arsenopyrite in the fine-grained dyke samples. Up to 6 ppm Mo was contained within the granitic phase, whereas lesser amounts of Mo were confined to the fine grained to aplite phases. Microprobe analyses of primary biotite as both phenocrysts and groundmass shows 0.55 avg. wt.% Cl and 0.21 avg. wt.% F, which are relatively concentrated compared to other high-grade porphyry deposits. Hydrothermally altered rocks, veins, and sulfides associated with the porphyritic suite result from buoyant magmatic-hydrothermal fluids from a deeper intrusion exsolving fluids (quenched porphyry related), depressurizing, and reacting with the host coarser grained granodiorite and even some of the dykes locally. Based on the geothermometry and geobarometry of amphibole (actinolite-magnesiohornblende), the crystallization temperature and pressure of the Evandale coarse-grained granite and aplite are 674–755 °C, 0.2–0.7 kbar (20–70 MPa) and 838 °C, 0.42–1.4 kbar (42–140 MPa), respectively. This is consistent with biotite formation at temperatures ranging from 670° to 760 °C, based on Ti-in-biotite thermometry. Also, zircon saturation temperatures of the earlier coarse-grained porphyritic granites and later fine-grained porphyry to aplitic dykes are 736 °C and 787 °C, respectively. Spatially and temporally associated gold deposits beside Evandale and within this region of southwestern New Brunswick suggests that these oxidized I-type intrusions are a potential source for distal, low sulfidation epithermal gold deposits in the region.

Effects of elevated temperature and copper exposure on the physiological state of the coral Galaxea fascicularis

The co-occurrence of elevated seawater temperature and local stressors (heavy metal contamination) affects the ecophysiology of phototrophic species, and represents a risk to the environmental quality of coral reefs. Therefore, we investigated the effects of both Cu alone and Cu in combination with elevated temperature (ET) on the physiology of the coral Galaxea fascicularis, and measured the parameters related to the photo-physiology and oxidative state. G.fascicularis is one of the dominant coral species in the South China Sea which exhibits strong adaptability to environmental stress. We exposed the common coral species G.fascicularis to a series of environmentally relevant concentrations of Cu at 29 °C (normal temperature, NT) and 32 °C (elevated temperature, ET) for 96 h. Single polyps were used in the experiments, which reduced individual variability when compared to the coral colonies. The results suggested that: i) Cu or ET had significant negative effects on the actual operating ability of photosystem Ⅱ (PSII), but not on the maximal chlorophyll fluorescence in darkness (Fv/Fm). ii) Symbiodiniaceae density was significantly reduced by high Cu concentrations, for Cu-NT and Cu-ET, a high concentration of Cu (40 μg/L) significantly impacted Symbiodiniaceae density, causing a 75.4% and 81.0% decrease, respectively. iii) the content of malondialdehyde (MDA) in coral tissues increased significantly under Cu-ET. iv) a certain range of copper concentration (25–30 μg/L) increased the pigment content of the Symbiodiniacea. Our results indicated that the combined stressors of Cu and ET made the coral tissue sloughed, caused the coral tissue damaged by lipid oxidation, reduced the photosynthetic capacity of the Symbiodiniacea, and led to the excretion of Symbiodiniacea.