Trace Amounts Of Metals Research Articles

Comparative analysis of the physicochemical properties and trace metal content of palm oil, from selected markets in Jos south and Jos north LGA, Plateau state, Nigeria

The quality of palm oil samples collected from three different markets in Jos South and Jos North Local Government Area of Plateau State were analyzed and evaluated using standard analytical laboratory procedures. The relative ranges of the physicochemical values obtained were as follows; Moisture Content (MC): 0.56 - 1.89, Iodine value (IV); 51.88 - 55.57 g I2/100g, Peroxide Value (PV): 0.98 - 4.16 mEq02/kg, Saponification Values (SV): 198.46 - 201.54 mgKOH/g, Acid Value (AV): 9.93 - 57.65, and Refractive Index (RI), 1.4576 - 1.4580. The moisture content, iodin value, pH values and acid values were found to exceed the Standard Organization of Nigeria (SON) permissible limits of moisture content (0.29 mgKOH/g), iodine value (45 - 53 mg I2/100g), pH (5 - 7 mg/L), and acid value (0.7 max mg/L) for edible oils respectively while the refractive index, saponification values, peroxide values falls within the SON allowable limits of refractive index (1.4612-1.4707 mg/L), saponification value (195-205 mgKOH/g) and peroxide value (10 mEq02/kg) respectively . The amounts of trace metals (Cu, Zn, Fe, Pb and Cd) determined in the palm oil using the atomic absorption spectrophotometer ranged from Cu(0.34 - 0.52 mg/l), Zn(1.58 - 2.33 mg/l), Fe(19.18 - 26.74 mg/l), Pb(2.87 - 4.06 mg/l) and Cd(1.58 - 2.24 mg/l). However, the levels of Zn, Fe, Pb and Cd exceeded the WHO/FAO recommended values of (1.50, 1.00, 0.05 and 0.02 mg/L) respectively while only Cu concentration was below the WHO/FAO limits of 2.00 mg/L for trace metals in edible palm oil. Consequently, the results of this study shows that the palm oil consumed from these selected markets does not meet the standard quality specification for edible palm oils and hence can post significant health threat to consumers. Therefore, food regulatory agencies should strengthen their surveillance to promote food and health safety of the populace.

Enhanced Rock Weathering as a Source of Metals to Promote Methanogenesis and Counteract CO2 Sequestration.

Enhanced weathering of (ultra)mafic rocks has been proposed as a promising approach to sequester atmospheric CO2 and mitigate climate change. However, these silicate rocks contain varying amounts of trace metals, which are essential cofactors of metallaenzymes in methanogens. We found that weathering of crushed peridotite and basalt significantly promoted the growth and methanogenesis of a model methanogen─Methanosarcina acetivorans C2A under the condition of excess substrate. The released trace metals from peridotite and basalt, especially Fe, Ni, and Co, accounted for the promotion effect. Observation at different spatial scales showed a close association between the rocks and cells. Proteomic analysis revealed that rock amendment significantly enhanced the expression of core metalloenzymes in the methylotrophic methanogenesis pathway. Our study uncovers a previously unrecognized but important negative effect of enhanced rock weathering on methane production, which may counteract the carbon sequestration effort.

Bioinspired, Carbohydrate-Containing Polymers Efficiently and Reversibly Sequester Heavy Metals.

Water scarcity and heavy metal pollution are significant challenges in today's industrialized world. Conventional heavy metal remediation methods are often inefficient and energy-intensive, and produce chemical sludge. To address these issues, we developed a bioinspired, carbohydrate-containing polymer system for efficient and selective heavy metal removal. Using ring opening metathesis polymerization, we synthesized polymers bearing amphiphilic glucuronate side chains capable of selectively binding heavy metal cations in mixed media. In samples containing high concentrations of heavy metals (>550 ppb), these polymers rapidly form a filterable precipitate upon metal capture, reducing the concentration of cation to <1.5 ppb within 3 min, as measured by inductively coupled plasma mass spectrometry. This system effectively removes cadmium ions from highly contaminated solutions to levels below the Agency for Toxic Substances and Disease Registry limit for Cd2+ in drinking water and selectively removes both Cd2+ and Pb2+ from lake water spiked with trace amounts of metal. Acidification triggers protonation of the glucuronate groups, releasing the heavy metals and resolubilizing the polymer. This capture-and-release process can be repeated over multiple cycles without loss of binding capacity. As such, this study introduces a novel class of recyclable materials with pH-responsive properties, offering potential for applications in water remediation and beyond.

Assessment of Water Quality and its Risk to Human Health Posed by Drinking Water from Open Sources in Jammu and Kashmir

Globally, the quality of the water has been connected to health outcomes. This study assessed the community practices surrounding water collection and storage, the physicochemical and bacteriological quality of drinking water supplied by the public health division from the point of use to the source in Anatnag, and the risks to human health associated with water consumption. A water quality assessment was performed on one hundred samples. To find out how the community moves water from its source to its point of use and stores it, questionnaires were employed. The majority of the homes (73%) do not purify their water before consumption, and many of them reported frequent interruptions in the water supply. Although total coliform and E. coli were not found in the water samples taken at the reservoir's source, It was discovered that there was significant E. Col and total coliform contamination in the samples taken from the street taps and the domestic storage containers at the point of use. During the rainy season, higher levels of E. Coli and total coliform were found than during the dry season. The amounts of trace metals in the drinking water samples fell below the World Health Organization's and Indian Standards' acceptable limit. Drinking water through ingestion and cutaneous channels has noncarcinogenic effects that are assessed using hazard quotient toxicity potential and cumulative hazard index. These effects are less than unity, which suggests that there may not be a major non-carcinogenic health risk associated with water intake. sporadic disruptions to the water supply as well as specific methods of water storage and transit by residents of the community raise the possibility of contaminated water. We suggest that the province of Kashmir receive a more steady supply of treated water and that its citizens be instructed in hygienic methods for carrying and storing drinking water from the point of origin to the place of use

Mass spectrometric analysis of transition metal complexes formed through contact of artificial sweat with circulating Euro coins

AbstractIt is well‐known that some metals/alloys sensitize the skin of susceptible individuals. Trace amounts of metals and chemical compounds containing metal ions can affect human health, i. e., cause allergy or inflammation. However, the details of this metal‐induced allergic reaction are not well understood. Complexes of nickel, copper, and zinc are known to be easily formed through contact of metal alloys with ubiquitously available organic compounds such as triacylglycerols, amino acids, urea, and fatty acids found in skin secretions or skin care products. Thus, an analytical technique is required to characterize and identify metal complexes formed on metallic everyday products, ideally offering a chemically specific, laterally resolved view of allergy‐causing processes. Here we present a mass‐spectrometry‐based analytical workflow to characterize metal‐containing compounds formed on the surface of 1‐euro coins when in contact with artificial sweat. This study identified different metal complexes by using tandem mass spectrometry (MS/MS). Surface imaging of 1‐Euro coins employing laser‐based mass spectrometry revealed the lateral distribution of Zn, Cu, and Ni complexes with low‐micrometer resolution.

Comparative Analysis of the Physico-Chemical Properties and Trace Metal Content of Palm Oil, from Selected Markets in Jos South and Jos North LGA, Plateau State, Nigeria.

The quality of palm oil samples collected from three different markets in Jos South and Jos North Local Government Area of Plateau State were analyzed and evaluated using standard analytical laboratory procedures. The relative ranges of the physicochemical values obtained were as follows; Moisture Content (MC): 0.56 - 1.89, Iodine value (IV); 51.88 - 55.57 g I2/100g, Peroxide Value (PV): 0.98 - 4.16 mEq02/kg, Saponification Values (SV): 198.46 - 201.54 mgKOH/g, Acid Value (AV): 9.93 - 57.65, and Refractive Index (RI), 1.4576 - 1.4580. The moisture content, iodin value, pH values and acid values were found to exceed the Standard Organization of Nigeria (SON) permissible limits of moisture content (0.29 mgKOH/g), iodine value (45 - 53 mg I2/100g), pH (5 - 7 mg/L), and acid value (0.7 max mg/L) for edible oils respectively while the refractive index, saponification values, peroxide values falls within the SON allowable limits of refractive index (1.4612-1.4707 mg/L), saponification value (195-205 mgKOH/g) and peroxide value (10 mEq02/kg) respectively . The amounts of trace metals (Cu, Zn, Fe, Pb and Cd) determined in the palm oil using the atomic absorption spectrophotometer ranged from Cu(0.34 - 0.52 mg/l), Zn(1.58 - 2.33 mg/l), Fe(19.18 - 26.74 mg/l), Pb(2.87 - 4.06 mg/l) and Cd(1.58 - 2.24 mg/l). However, the levels of Zn, Fe, Pb and Cd exceeded the WHO/FAO recommended values of (1.50, 1.00, 0.05 and 0.02 mg/L) respectively while only Cu concentration was below the WHO/FAO limits of 2.00 mg/L for trace metals in edible palm oil. Consequently, the results of this study shows that the palm oil consumed from these selected markets does not meet the standard quality specification for edible palm oils and hence can post significant health threat to consumers. Therefore, food regulatory agencies should strengthen their surveillance to promote food and health safety of the populace.

Effects of calcination temperature on the adsorption ability of polyaluminum chloride (PAC) sludge-derived granules for As(V)

The effect of calcination on the adsorption of As(V) by polyaluminum chloride (PAC) sludge-derived adsorbents in aqueous solution was investigated, and the As(V) adsorption ability of the adsorbent calcined at the optimal temperature was tested in batch and column modes. The characterization results for the calcined sludges indicated the formation of a porous framework and the transition of amorphous Al2O3 to its crystalline form in the sludge calcined at 500 °C. However, the adsorbents fabricated at temperatures >500 °C exhibited less adsorption of As(V) because of transformation of a crystalline phase. On the basis of the results of comparative As(V) adsorption experiments, the sludge calcined at 500 °C (PA500) was selected as the optimal adsorbent. The adsorption of As(V) by PA500 was terminated within 6 h, and its maximum adsorption capacity was 15.9 mg/g when the absorption data were fit to the Langmuir isotherm model. The adsorption of As(V) exhibited a low pH dependence and was strongly affected by the existence of P(V) in form of PO43−. The column results showed that a column filled with 7 g of PA500 maintained an As(V) concentration of <10 μg/L during 150 h of operation at 50 μg/L As(V) and a 1 mL/min flow rate. The stability of the sludge calcined at 500 °C was well demonstrated by a smaller amount of trace metals being leached from the sludge compared with that leached from other sludges. In conclusion, calcination of PAC sludge at an optimal temperature is a promising to fabricate As(V) adsorbents.

Leaching tests reveal fast aluminum fluoride release from ashfall accumulated in La Palma (Canary Islands, Spain) after the 2021 Tajogaite eruption

Leaching tests conducted on fresh ashfall samples taken soon after the onset of the 2021 Tajogaite eruption occurred at the Northwest flank of the Cumbre Vieja Volcanic Ridge in La Palma (Canary Islands) have revealed relevant geochemical trends which have important environmental significance and practical implications. The ashfall deposited on most of the island during the eruptive episode (9/19/2021–12/13/2021) contains, in addition to common constituents in volcanic tephra (e.g. volcanic glass, silicates like olivine, amphibole or pyroxene, magnetite, etc.) a significant amount of very fine-grained (diameter range of 10–500 μm) crystals of highly soluble salts like AlF3, NaCl, KCl or CaSO4. These salts likely crystallized at high temperature by interaction of acid volatile phases (e.g., HF, HCl, SO2) with volcanic glass and silicate minerals during the ascending flow of the eruptive plume, though some adsorption of marine aerosols on ash surfaces during the subsequent descending flow and transport to more distal areas could have also taken place. The dissolution of these salts in the leaching tests (conducted with ultrapure distilled water during 90 min) reveals a fast release of important amounts of F−, Cl− and SO42− as major anions, and Al3+, Na+, K+, Ca2+, Mg2+ and Si4+ as major cations, in addition to minor amounts of trace metals like Mn2+, Zn2+, Ba2+ or Sr2+. The release of F− and Al3+, both potentially toxic and travelling together as aluminum fluoride species (AlF3, AlF2+, AlF4−) is particularly noteworthy and represents a potential threat for the environment (including soils, surface waters or groundwater existing beneath the ashfall layers covering the island) as well as for food safety (e.g. banana plantations) and/or human health (exposure to F- or Al-contaminated water). On the other hand, the tephra does not represent an environmental hazard as regards to other toxic elements traditionally reported for ashfall released in other volcanic eruptions, such as As, Pb, Hg or Se, which were always close to or below the limit of quantification. Besides, the Tajogaite 2021 ashfall shows a significant acid-neutralizing capacity as a result of the partial dissolution of volcanic glass in the F-rich solutions. This study presents a discussion of geochemical and mineralogical controls on element mobility during ashfall/water interaction in the environment which may be worth considering in any future restoration or land management plans for the island.

Spatial analysis of heavy metals in septic tank sewage

Heavy metals get to humans through food, water, air, and industrial activities. They arrive at septic tanks through the excretory products of man and undergo anaerobic bioremediation. Effluent and sludge sewage in both chambers of the tank contains various amounts of trace metals. The research analyses the spatial distribution of heavy metals in the effluent and sludge components of the septic tank during bioremediation. Effluent and sludge samples were randomly collected from three study locations in southern Nigeria, and composite samples were made for each of these study locations. Nine trace metals were analysed using standard methods by the American Public Health Association (APHA) for water and wastewater examination. Fe, Mn, Zn, Cu, and Cr were the most abundant. Effluent heavy metals concentrations were higher in the inlet chamber. There were strong positive correlation (r = 0.90, 0.99, and 0.99) between the effluent and sludge samples. P-values obtained from the ANOVA at a 0.05 significance level confirmed the correlation values. Multivariate charts and regression analysis gave R2-values in the range of 0.3045 – 0.3724 in the study with a mean value of 0.33. In conclusion, the effluent and sludge samples were strongly correlated and all the metal types analysed were also present in the sludge in similar proportions. The sludge contained significant levels of trace metals with dire implications for the environment.

Demonstrating the absence of metal ion contamination in operando PEM fuel cells utilizing unmodified stainless steel bipolar plates

Using stainless steel as material for bipolar plates (BPPs) in proton exchange membrane fuel cells (PEMFCs) carries a perceived risk of corrosion and subsequent metal ion contamination of the membrane electrode assembly (MEA). However, assessments in literature on this hazard to PEMFC systems have been based on ex-situ corrosion studies, where general assumptions made on the BPP environment might not be a correct simulation of real on-site conditions. In this contribution, uncoated BPPs from stainless steel grades 304 L, 316 L and 904 L were subjected to in-situ hybrid endurance/stress testing to simulate realistic conditions in operating fuel cell systems and re-evaluate the need of additional corrosion protection. A post analysis of the plates showed no signs of surface dissolution on any of the tested samples and the concentration of iron in the MEA averaged 7 to 10 ppm for uncoated samples and 7 to 11 ppm for coated and graphitic reference tests, displaying a negligible amount of trace metals compared to critical thresholds found in literature. Contact resistance values were stable for all samples and observable changes in cell performance and voltage degradation was confirmed to be unrelated to the presence of uncoated bipolar plates. The combined effects of decoupling of bipolar plate surface potentials from electrode potentials and operational control of stable gas flow compositions to sustain stainless steel surface passivation, were identified as explanation for the experimentally observed corrosion resistance of uncoated stainless steel plates in PEMFCs.

Estuarine flocculation dynamics of organic carbon and metals from boreal acid sulfate soils

Abstract. Flocculation of riverine dissolved organic matter to the particulate form in estuaries is an important mechanism for capturing dissolved metals to newly formed organic particles, regulating the metal transport from land to sea. The process is particularly relevant for rivers draining boreal acid sulfate soils of western Finland, which are known to deliver large amounts of trace metals with detrimental environmental consequences for the recipient estuaries in the eastern Gulf of Bothnia in the northern Baltic Sea. This is the first study to investigate dissolved metal (Al, Fe, Mn, Co, and Cu) association with flocculating organic particles in the laboratory, by mixing of acidic metal-rich water from acid-sulfate-soil-impacted rivers and particle-free artificial seawater. Water samples were collected in April 2021 from the Laihianjoki and Sulvanjoki rivers in western Finland. Experiments with an in situ laser-diffraction-based particle size distribution sensor and a multiparameter water quality sonde were run to continuously monitor the development of a suspended particle pool over the salinity gradient from 0 to 6, corresponding to the salinity range observed in these estuarine systems. Flocculator experiments with discrete salinity treatments were carried out to investigate metal behaviour with the collection of flocculated material on glass fibre filters. Filtrate was analysed for coloured dissolved-organic-matter absorbance and fluorescence for the characterization of potential changes in the organic matter pool during the flocculation process. Retentate on the filter was subjected to persulfate digestion of organic particles and metal oxyhydroxides (pH &lt; 2.3), and the digestion supernatants were analysed for metal concentrations. The laboratory experiments showed strong transfer of Al and Fe already at a salinity of 0–2 to newly formed organically dominated flocs that were generally larger than 80 µm. Very strong coupling between the decrease in humic fluorescence and the increase in organically bound Al demonstrated that Al transfer to the flocs was stronger than that of Fe. The flocs in the suspended particle pool were complemented by a smaller population of Al- and Fe-oxyhydroxide-dominated flocculi (median size of 11 µm) after pH exceeded ca. 5.5. Cobalt and Mn transfer to the particle pool was weak, although some transfer to Mn oxyhydroxides as well as Co association with the flocs took place. Up to 50 % of Cu was found to be bound to humic substances in the flocs in the river waters, and this proportion did not significantly change during mixing with seawater. The findings of this study demonstrate that salinity and pH are important independent but connected controls of the flocculation behaviour of dissolved metals from boreal acid sulfate soils and the seaward transport and environmental consequences of the metals in the marine environment.

The distribution and enrichment of trace elements in surface and core sediments from the Changjiang River Estuary, China: Evidence for anthropogenic inputs and enhanced availability of rare earth elements (REE)

Huge amount of trace metals emitted through manmade activities are carried by the Changjiang River into the East China Sea. Most of them deposit in the Changjiang River Estuary and threaten the regional aquatic environment. In this study, major and trace elements of 34 archive surface sediments and two cores are examined. Sequential extraction procedures were also performed on surface sediments from 12 sites. We found that Tl, Tm, Er show distinct accumulation in surface sediments in the order of Tm > Tl > Er. Particularly, abnormally elevated HREE are observed mainly in those sites near the mouth of the estuary. Most elements exhibit an obvious reduction in the upper 30 cm of core B8, reflecting a decrease of sediment discharge from Changjiang River runoff. The increase of some trace elements recorded in the upper 20 cm of core C3 demonstrates a distinct local anthropogenic input in recent years.

Type of pots used in cooking may influence the iron content of commonly consumed vegetables in Nigeria: A laboratory based comparative study.

Iron deficiency anemia is a major public health problem, especially in resource-poor countries. Cooking pots may contribute some appreciable amount of trace metals into food by way of leaching. The effects of iron and aluminum cooking pots on iron content of two commonly consumed vegetables were investigated. The pH content was determined using pH meter while the moisture was determined using a moisture content analyzer. The iron content was determined using Atomic Absorption Spectrophotometer (AAS). The mean difference in the pH of African spinach (VA) 7.2±0.0 and Lagos spinach (VL) 7.2±0.0 was not significant (p>0.05). The mean moisture content of African spinach and Lagos spinach were 8.7±0.0 g/100g and 18.2±0.1 g/100g respectively. The difference in the moisture content was however statistically significant (p <0.05). The iron content of African spinach boiled in aluminum pot [VA (Al)] (5.9±0.0 mg/100g) was statistically different from the fresh sample of African spinach, VA (12.7±0.2 mg/100g) (p <0.05) but the amount of iron lost as a result of boiling in aluminum pot was 6.8mg / 100g. The iron content of African spinach boiled in iron pot [VA (Fe)] (15.9±0.0 mg/100g) was also statistically different from the fresh sample of African spinach (p <0.05). However, the amount of iron added (leached) as a result of boiling was 3.2 mg/100g. The same trend was observed in the Lagos spinach boiled in aluminum and iron pots. However, the iron lost as a result of boiling in aluminum pot (0.2 mg/100g) was not significant (p>0.05) while a greater amount of iron (5.5 mg/100g) was added (leached) when Lagos spinach was boiled in iron pot. Cooking in iron pots will conserve iron during boiling and improve iron intake from the vegetables.

Nutritional profile and heavy metal contamination of nursery, grower, and finisher feeds of tilapia (Oreochromis niloticus) in Bangladesh

Tilapia, the third most cultured fish, is a part of the daily diet of more than 50% of the population of Bangladesh. Thus, adequate nutrition and toxic metal-free tilapia fish feeds are the prerequisites of sustainable aquaculture. The present study was carried out to investigate the nutritional profile and heavy metal pollution in nursery, grower, and finisher types of feeds of tilapia commercially available in Bangladesh. The proximate composition (moisture, protein, lipid, ash, crude fibre, and carbohydrate), mineral nutrients, fatty acid profile, and heavy metals (Pb, Cd, Cr, Ni, Cu, and Zn) of feed samples were assessed. Low protein content and the absence of essential fatty acids mark the feeds as low-quality diets. A significant amount of trace metals were also detected in the feeds, posing a direct threat to the health of the fish and, ultimately, to consumers. The results revealed the highest Zn concentration in all tilapia feed samples. The descending order of heavy metal concentrations was identified as Zn>Ni>Pb>Cu>Cr in nursery feeds, Zn>Cu>Cr in grower feeds, and Zn>Ni>Cu>Cr>Cd in finisher feeds. Pb and Cr values were higher than the recommended values set by FAO. Therefore, strong monitoring is recommended to ensure the optimum quality and safety feeds.

Investigating the effect of nickel concentration on phytoplankton growth to assess potential side-effects of ocean alkalinity enhancement

Abstract. Ocean alkalinity enhancement (OAE) is a proposed method for removing carbon dioxide (CO2) from the atmosphere by the accelerated weathering of (ultra-)basic minerals to increase alkalinity – the chemical capacity of seawater to store CO2. During the weathering of OAE-relevant minerals relatively large amounts of trace metals will be released and may perturb pelagic ecosystems. Nickel (Ni) is of particular concern as it is abundant in olivine, one of the most widely considered minerals for OAE. However, so far there is limited knowledge about the impact of Ni on marine biota including phytoplankton. To fill this knowledge gap, this study tested the growth and photo-physiological response of 11 marine phytoplankton species to a wide range of dissolved Ni concentrations (from 0.07 to 50 000 nmol L−1). We found that the phytoplankton species were not very sensitive to Ni concentrations under the culturing conditions established in our experiments, but the responses were species-specific. The growth rates of 6 of the 11 tested species showed generally limited but still significant responses to changing Ni concentrations (36 % maximum change). Photosynthetic performance, assessed by measuring the maximum quantum yield (Fv/Fm) and the functional absorption cross-section (σPSII) of photosystem II (PSII), was sensitive to changing Ni in 3 out of 11 species (35 % maximum change) and 4 out of 11 species (16 % maximum change), respectively. The limited effect of Ni may be partly due to the provision of nitrate as the nitrogen source for growth as previous studies suggest higher sensitivities when urea is the nitrogen source. Furthermore, the limited influence may be due to the relatively high concentrations of synthetic organic ligands added to the growth media in our experiments. These ligands are commonly added to control trace metal bioavailability and therefore for example “free Ni2+” concentrations by binding the majority of the dissolved Ni. Our data suggest that dissolved Ni does not have a strong effect on phytoplankton under our experimental conditions, but we emphasize that a deeper understanding of nitrogen sources, ligand concentrations, and phytoplankton composition is needed when assessing the influence of Ni release associated with OAE.

The Impact of Natural Deep Eutectic Solvents and Extraction Method on the Co-Extraction of Trace Metals from Fucus vesiculosus.

In recent years, natural deep eutectic solvents (NADES) have been widely investigated for the extraction of food and medicinal plants as well as seaweeds. However, the ability of NADES for trace elements co-extraction from natural sources is not well investigated. The aim of this study was to investigate the ability of common NADES for trace elements co-extraction from Fucus vesiculosus. All of the tested NADES did not recover As and Co (concentration <LOQ). Moreover, all of the tested NADES provided a low recovery (<9%) of Ba, Ca, Fe, Mg, Mn, Sr, and Zn. The method of extraction had not shown a statistically significant effect on the co-extraction of all elements (excluding Ba and Ca). In contrast, the water content in NADES was significantly affected on the recovery of Ba, Ca, Mg, Mn, Sr, and Zn. The recovery of Al and Cr was relatively high and considerably varied (from 1.5 to 59.9%). NADES comprising lactic acid:glucose:H2O (5:3:1) provided the lowest contents of all elements, and the highest extracted amounts were obtained employing water contents of 60–80%. The calculated daily intake of all the elements contained in NADES extracts were less than the daily dose risk estimators. The hazard quotients, hazard indexes, and carcinogenic risk calculated for all trace elements and their combination were considerably less than 1. This evidences no health risk, and carcinogenic risk after topical application of all studied NADES. For the first time, the results of the current study demonstrated that NADES extracts of F. vesiculosus contain a lower amount of trace metals and are safer than the extracts obtained with water and 70% acetone. This indicates a significant advantage for NADES compared with the other solvents.

Polymetallic nanoparticles in pyrite from massive and stockwork ores of VMS deposits of the Iberian Pyrite Belt

This paper reports the first-ever study on nanoscale mineralogy in pyrite from the volcanogenic massive sulfide (VMS) deposits of the Iberian Pyrite Belt, southwestern Iberian Peninsula. It targeted colloform-textured grains formed at low temperature in the distal part of a polymetallic (Pb-Zn) massive sulfide lens hosted in felsic volcanoclastic rocks from the Masa Valverde deposit, and euhedral-textured grains (re)-deposited by higher temperature fluids in the Co-Au rich stockwork hosted in black shales of the Filón Norte orebody of the Tharsis deposit. The results acquired by a combination of techniques for mineral microanalysis and characterization (i.e., reflected light, FE-SEM, EPMA, LA-ICP-MS, HRTEM-STEM and TEM-EDS) show that trace amounts of metals (Au, Ag, As, Pb, Sb, Cu, Co) are incorporated as both lattice-bound and into nanoparticles (NPs). The mode of occurrence is strongly related with the evolutionary history of the mineralization. In the colloform pyrite collected from the massive sulfide lens, a rhythmic banding/oscillatory zonation with up to 3 wt% As, 5,000 ppm Pb, 1,070 ppm Sb and 750 ppm Cu is defined by the coexistence of several nano-sized layers (5 to 100 nm) and NPs (<100 nm) containing all these metals. The NPs include galena [PbS], tetrahedrite [(Cu,Fe)12Sb4S13)] and arsenopyrite [FeAsS] that exhibit euhedral and less frequently anhedral (i.e., droplet-like) morphologies being both randomly and preferentially oriented with respect to As-rich pyrite bands they are usually associated with. These features suggest formation of the NPs via direct deposition from the hydrothermal fluid(s) or low-temperature melts entrained in them as well as exsolution of trace elements originally dissolved in the As-rich pyrite structure. Additionally, some of these NPs are connected to late fractures disrupting the chemical zoning in colloform pyrite documenting a third genetic type of NPs related to late infiltration of fluids post-dating pyrite formation. In contrast, euhedral pyrite from the stockwork form well-developed homogeneous grains with discrete porous areas relatively depleted in Fe (45.20 wt%), and As (8,800 ppm) but enriched in Co (5,900 ppm). At the nanoscale, Co-enriched domains show patchy zoning defined by irregular distribution of Co– and As-rich bands of 200–500 nm in thickness. These nanometer Co– and As-rich bands are often disrupted by micron-to-nano-sized polycrystalline Au-Ag-Hg particles that fill voids in porous areas. Contact morphology anatomy between Co-rich pyrite and inclusions suggests that the Au-Ag-Hg particles are negative crystals occupying spaces originated in pyrite by coupled dissolution-reprecipitation reaction. Likewise, HRTEM observations along such pyrite-inclusion contacts show the existence of polycrystalline matrices in both pyrite and Au-Ag-Hg inclusions, the former consisting of nano-sized domains of arsenian pyrite and/or arsenopyrite in As-free pyrite and the Au-Ag-Hg inclusions made up of multiple crystal domains including nano-crystallites of Au0/Ag0 or electrum. Recognition of crystalline nanodomains and NPs in these polycrystalline matrices raises the possibility that Au NPs or nanomelts already present in the hydrothermal fluid catalyzed the formation of these heterogeneous crystals.

Screening of bio-derived surfactants for soil washing of PAHs: effects of substrate sources and trace metals distribution

In this study, we screened the performance of aqueous extracts of Talinum triangulare (AET) and soap solution prepared from Hura crepitans seed oil saponified by aqueous solution of ashed plantain peels (HCS) for removal of naphthalene and phenanthrene from soil. The distribution of trace metals in the soil before and after soil washing was also investigated. The results revealed maximum removal efficiencies after 25 min washing time of 96.25, 96.14, and 25.70% naphthalene, for Tween 80, AET and HCS, respectively. While for phenanthrene, the recorded maximum removal efficiencies after 25 min washing time were: 91.80, 26.00, and 94.0 for Tween 80, AET and HCS, respectively. Based on results from other experiments, AET generally showed slightly lower removal efficiencies compared to the commercial Tween 80 surfactant. Also, the results revealed that the three remediants affected the distribution of trace metals (Cd, Pb, and Zn) in the soil after surfactant washing. Based on the amount of trace metals extracted, the performance of the three remediants are as follows: AET &gt; Tween 80 &gt; HCS. The performance of AET has been attributed to the presence of multiple heteroatomic moieties for trace metals adsorption and moderation of the acidic conditions of the soil.

Remediation for trace metals in polluted soils by turfgrass assisted with chemical reagents

Trace metal pollution in soils is one of the universal environmental problems in the world. Phytoremediation is a green, safe, ecological, and economic method to achieve continuous reduction of soil pollutants. Turfgrass is a plant with great landscape value and has considerable biomass when used for remediation of trace metal contaminated soil. However, its remediation ability needs to be improved in future application. The combined application of turfgrass, citric acid (CA) and auxin (gibberellin, GA3) were applied in the phytoremediation of an artificial nutritive soil derived from sludge, and a field scale orthogonal experiment (L9) was conducted to understand the interaction effect and obtain the optimum phytoremediation. Experimental results showed that the types and cultural patterns of turfgrass mainly determined plant height, root length and trace metal concentration in turfgrass, however CA treatment was prone to increase the aboveground biomass and the concentrations of most trace metals in turfgrasses, especially the concentration of Ni in turfgrass. GA3 spraying significantly increased the concentration of Cd in turfgrass. The culture patterns of turfgrass played 42.4% influence on acid-extractable Cd, while CA applying had 53.8% influence on the acid-extractable Ni. The annual phytoextraction amount of trace metals based on five mowing a year were proposed to assess the remediation ability of treatments, which of the combination treatment (T3, intercropping Zoysia matrella and Lolium perenne, and applying 400 mg kg−1 CA and 30 mg kg−1 GA3) were 1.6–2.1 times higher CK group. This research provides technical reference for intercropping turfgrass for remediation of trace metals in sludge-derived nutritive soil.

Hematological, Biochemical and Immunological Responses of Estuarine Catfish Mystus gulio (Hamilton 1822) After Exposure to Lead (Pb)

Due to increased industrialization in developing countries some of the toxic substances are being increased in day-to-day life. Living organisms need some trace amounts of metals like copper, manganese, zinc etc. but some of the non-essential toxic heavy metals are also accumulated in the body of living organisms which may cause damages to the immune organs of the organism. The present study investigated the impacts of sublethal dosage of inorganic Lead acetate on the hematological, biochemical and immunological responses of the brackish water fish Mystus gulio. The LC50 at 96 h was determined by the Probit method. The experiment was performed for 30 days of exposure of lead acetate (4 mg/l) to the fish Mystus gulio. After exposure to lead nitrate hematological (hemoglobin, RBC, WBC, PCV, neutrophil, eosinophil and platelet), biochemical (glucose, protein, albumin and globulin) and immunological (IgM) parameters were analyzed. A decrease was seen in the RBC count, hemoglobin, PCV, MCV, MCH, MCHC, protein, albumin and globulin whereas an increase was seen in WBC count, neutrophils, eosinophils, ESR, platelet count, glucose and Immunoglobulin (IgM).