Barium Concentrations Research Articles

Exposures in nail salons to trace elements in nail polish from impurities or pigment ingredients - A pilot study.

Nail polishes have evolved considerably. Toxic elements, such as lead, have been found in nail polish, and it is unclear if new finishes using metallic effect pigments may be contributing to metals exposure in nail technicians. We characterized concentrations of trace elements in 40 nail polishes, 9 technicians' urine, and 20 technicians' toenail clippings from 8 nail salons in the Boston area in 2017. We also collected 24 salon surface wipes from 3 of the salons. Antimony was not disclosed as a nail polish ingredient, yet concentrations (<15μg/g) were above existing cosmetics guidelines (0.5μg/g) in five (13%) of the samples. Aluminum (<11,450μg/g), barium (<11,250μg/g), iron (<3,270μg/g), and magnesium (<2375μg/g) were disclosed as ingredients and were also found on salon surfaces where nail polish was stored or used. Heavy metal impurities in nail polish were not detected for cadmium. Lead and nickel were found at low concentrations (<0.40μg/g lead, <0.67μg/g nickel). Tin (p=0.003) concentrations were higher in nail polish with finishes compared to without. Barium and strontium (both p=0.0001) concentrations were higher for red nail polishes compared to all other colors. Of those elements in nail polish and salon surfaces, aluminum and iron were detected in toenails, manganese was detected in urine and toenails, and barium was detected in urine at comparable levels to the general population. Besides preventable antimony levels in nail polish, individual metals in nail polish did not appear to be from impurities but mainly from colorants (i.e., pigments) and not major contributors to nail technician exposure. It is unclear if low-level chronic metals mixtures in nail salons are of health concern.

Evaluation of the concentrations of elements at trace level in the Serinhaem River estuary, Bahia, Brazil, using chemometric tools

The Serinhaém River estuary is located in the Environmental Protection Area (EPA) of Pratigi, in the State of Bahia, Brazil, which is recognized for being a relatively well-preserved environment. In this work, the levels of aluminum (Al), arsenic (As), barium (Ba), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) were determined to evaluate the behavior of these chemical elements through geochemical parameters. Eighty-one sediment samples were collected in five sediment cores along the estuarine region. The results of the composition of the Serinhaém river basin showed high levels of Fe, Al, and Mn in the sediment samples. By using Principal Component Analysis, it was observed that 55.8% of the elements have a significant correlation with Fe, Al, and Mn, which may have the same origin or be associated with Fe and Mn oxy-hydroxides, and aluminosilicates. Although Cr, As, and V are correlated with Fe, Mn, and Al, their concentrations are above those established by NOAA, suggesting adverse effects on biota. Barium concentrations increased toward the outfall, where it meets the Camamu Bay, which is naturally enriched with this element. It was also possible to observe that along with the vertical profile, there were no variations in the concentrations of the elements, while along the estuary, it was possible to verify that the cores differ from each other. The estuary of the Serinhaém River can be considered to be influenced relatively little by human activities, and its concentrations can be considered as a base level for this coastal region.

Corrigendum to: Identifying physiological and environmental influences on otolith chemistry in a coastal fishery species

Otolith (ear stone) chemistry provides powerful insights into the lives of fish. Although frequently used to reconstruct past environments, the influence of physiology remains unsettled. As such, we investigated the relationships between otolith chemistry, physiological factors and environmental factors in an iconic fishery species, snapper (Chrysophrys auratus). Lifetime otolith profiles were analysed of carbon (δ13C) and oxygen (δ18O) isotopes, and elemental concentrations of lithium (Li:Ca), magnesium (Mg:Ca), manganese (Mn:Ca), strontium (Sr:Ca), and barium (Ba:Ca). Mixed-effects modelling alongside a detailed literature review was used to investigate physiological (age, otolith growth rate, fish size, sex) and environmental influences (sea-surface temperature and chlorophyll-a) on otolith chemistry. Carbon isotopes and magnesium related to physiological factors, suggesting their potential as physiological proxies. Physiology also weakly related to strontium and lithium. By contrast, oxygen isotopes, barium, and manganese (except for natal signatures) were suggested to provide insights into past environments. Our study stresses the importance of consistency in biological characteristics for study designs, and highlights the potential of physiological proxies for distinguishing between populations in uniform water bodies. This study has not only reinforced our confidence in field applications of otolith chemistry, but has furthered our understanding of the influence of physiology.

Structure and transport properties of triple-conducting Ba x Sr1-x Ti1-y Fe y O3-δ oxides.

In this work, BaxSr1−xTi1−yFeyO3−δ perovskite-based mixed conducting ceramics (for x = 0, 0.2, 0.5 and y = 0.1, 0.8) were synthesized and studied. The structural analysis based on the X-ray diffraction results showed significant changes in the unit cell volume and Fe(Ti)–O distance as a function of Ba content. The morphology of the synthesized samples studied by means of scanning electron microscopy has shown different microstructures for different contents of barium and iron. Electrochemical impedance spectroscopy studies of transport properties in a wide temperature range in the dry- and wet air confirmed the influence of barium cations on charge transport in the studied samples. The total conductivity values were in the range of 10−3 to 100 S cm−1 at 600 °C. Depending on the barium and iron content, the observed change of conductivity either increases or decreases in humidified air. Thermogravimetric measurements have shown the existence of proton defects in some of the analysed materials. The highest observed molar proton concentration, equal to 5.0 × 10−2 mol mol−1 at 300 °C, was obtained for Ba0.2Sr0.8Ti0.9Fe0.1O2.95. The relations between the structure, morphology and electrical conductivity were discussed.

Role of TeO2 coordination with the BaF2 and Bi2O3 on structural and emission properties in Nd3+ doped fluoro phosphate glasses for NIR 1.058 μm laser emission

Fluoro phosphate glasses with different contents of barium and bismuth (8, 11, 14, 17 and 20 mol %) doped with Nd 3+ were prepared by melt quenching technique. Importance of these modifier ions on structural transformation were carried out using XRD, FTIR, FT-Raman and 31 P MAS NMR characterizations. 31 P MAS NMR spectra revealed that structural modifications due to Bi 2 O 3 are more when compared with BaF 2 in this fluoro phosphate glass matrix. Three phenomenological Judd-Ofelt (J-O) parameters Ω λ (λ = 2, 4, 6) have been derived from the absorption spectra of Nd 3+ doped barium and bismuth fluoro phosphate glasses. From the Judd-Ofelt parameters, transition probabilities (A), branching ratios (β) of certain transitions and radiative lifetimes of certain excited states of Nd 3+ are extracted and reported. From the emission spectra, emission cross sections (σ e ), band gains (σ e xΔλ eff ) and optical gain parameters (σ e xτ R ) were reckoned for the observed emission bands in these phosphate glasses. It is observed that barium glass resulted higher laser spectroscopic parameters (σ e , σ e xΔλ eff , σ e xτ R ) which are crucial characteristics for exploring promising laser applications. Impact of Ba 2+ and Bi 3+ on luminescent properties of Nd 3+ doped fluoro phosphate glasses has been examined in search of solid sate gain medium for laser emitting NIR light around 1.058 μm for photonic applications. •Nd 3+ doped barium and bismuth flouro phosphate glasses are prepared by melt quenching technique. •Structural analysis for present fabricated vitreous material with the help of FT-Raman, FTIR and 31 P NMR spectra. •Addition of Alkaline earth fluoride BaF 2 enhance the spectroscopic properties. •The Nd 3+ doped Barium flouro phosphate glasses could be promising host in the NIR region around 1.058 μm.

Identifying physiological and environmental influences on otolith chemistry in a coastal fishery species

Otolith (ear stone) chemistry provides powerful insights into the lives of fish. Although frequently used to reconstruct past environments, the influence of physiology remains unsettled. As such, we investigated the relationships between otolith chemistry, physiological factors and environmental factors in an iconic fishery species, snapper (Chrysophrys auratus). Lifetime otolith profiles were analysed of carbon (δ13C) and oxygen (δ18O) isotopes, and elemental concentrations of lithium (Li:Ca), magnesium (Mg:Ca), manganese (Mn:Ca), strontium (Sr:Ca), and barium (Ba:Ca). Mixed-effects modelling alongside a detailed literature review was used to investigate physiological (age, otolith growth rate, fish size, sex) and environmental influences (sea-surface temperature and chlorophyll-a) on otolith chemistry. Carbon isotopes and magnesium related to physiological factors, suggesting their potential as physiological proxies. Physiology also weakly related to strontium and lithium. By contrast, oxygen isotopes, barium, and manganese (except for natal signatures) were suggested to provide insights into past environments. Our study stresses the importance of consistency in biological characteristics for study designs, and highlights the potential of physiological proxies for distinguishing between populations in uniform water bodies. This study has not only reinforced our confidence in field applications of otolith chemistry, but has furthered our understanding of the influence of physiology.

Assessment of Pollutants in Soils and Groundwater from the Coastal Plain of Paraíba do Sul River Delta, RJ, Brazil

In developing countries, the quality of the available freshwater is deteriorating mainly due to pollution. Underground water bodies are important resources, taking into account that they are usually more isolated and also protected from anthropogenic influence. Within this context, the present study aimed to assess trace metals, nitrate and organic contaminants in groundwater and soils from 10 bore wells located at the coastal plain of the Paraíba do Sul river delta. Groundwater of the study area revealed elevated concentrations of arsenic, iron, manganese and barium, surpassing the limits established by Brazilian legislation as well as the limits established by other regulatory agencies. As, Fe and Ba reached concentrations as high as 242.70, 31 919 and 4.041 µg.l-1 in groundwater. Despite the elevated values, results suggested a reducing environment and the contaminants appear to have a natural geogenic origin, which is corroborated by past studies in the same area. Soils of the aquifer presented low levels of trace metals, corroborating the hypothesis of geogenic contamination in groundwater. No significant differences among the bore wells were observed regarding trace metals in soils, and concentrations found in the present study were much lower than the ones found in impacted aquifers around the world. No PCB's were detected in groundwater or soils. Nitrate concentrations in groundwater were within the limits recommended by Brazilian legislation.

The Effects of Barium Concentration Levels on the Pulmonary Inflammatory Response in Barium Aspiration Models

The Effects of Barium Concentration Levels on the Pulmonary Inflammatory Response in Barium Aspiration Models

Accumulation of Toxic Elements in Bone and Bone Marrow of Deer Living in Various Ecosystems. A Case Study of Farmed and Wild-Living Deer.

Simple SummaryToxic elements (TE) such as Be—beryllium, Al—aluminum, As—arsenic, Cd—cadmium, Sb—antimony, Ba—barium, Pb—lead, V—vanadium, Ni—nickel, Tl—thallium may negatively impact bone cells even at low concentrations. This is especially undesirable when they are released from the bone marrow. Therefore, in this study, the concentrations of TE in the bone marrow and bones of wild and farmed red deer were compared to evaluate the influence of the external environment on the absorption and accumulation of various harmful elements. The obtained results show that higher accumulation was detected only in the case of As, Ba, and Pb in the bones of the wild red deer, compared to the farmed group. In turn, higher levels of Al in the bone marrow and bones, as well as Cd in the bones were recorded in the farmed animals. Although the study involved animals living in an area that is regarded as being unpolluted, the concentrations of some heavy metals were higher than values reported from industrial regions.The aim of the study was to determine the concentrations of toxic elements accumulated in the bone marrow and bones (Cervus elaphus). The studies were carried out on two groups of young stags: farmed (n = 6) and wild (n = 9). Their body weights were measured and bone and bone marrow samples were collected. The concentrations of toxic elements were analyzed using the inductively coupled plasma mass spectrometry technique. The mean aluminum content in the bone marrow and bones of the farmed animals was significantly higher than in the wild group (p < 0.05). The mean concentration of arsenic, barium and lead in the bones of the wild red deer was significantly higher than in the bones of the farmed animals (p < 0.05), while the cadmium concentration in the bones of the farmed red deer exceeded the value determined in the wild animals. A significant difference was found between the mean concentrations of aluminum, arsenic, barium, lead, vanadium and nickel in the bone marrow and bones of both red deer groups (p < 0.05). Although the study involved animals living in an uncontaminated area, the concentrations of some heavy metals were higher than values reported from industrial regions.

A probabilistic-deterministic analysis of human health risk related to the exposure to potentially toxic elements in groundwater of Urmia coastal aquifer (NW of Iran) with a special focus on arsenic speciation and temporal variation

The human exposure to groundwater contamination with toxic elements is a worldwide concern. In this study, multivariate statistics coupled with probabilistic and deterministic risk estimation approaches were applied to 173 groundwater samples of Urmia aquifer (UA) to evaluate human health risks in relation to the consumption of groundwater contaminated with toxic elements. The concentrations of aluminum (Al), barium (Ba), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), and zinc (Zn) were below their corresponding maximum permissible levels as advised by the WHO, USEPA, and Iranian guidelines. However, arsenic (As), lead (Pb), iron (Fe), and selenium (Se) were elevated at some locations. Monte Carlo simulation-based probabilistic risk estimation suggested ingestion as the dominant pathway for water-hosted element exposure. Mean values of hazard index estimated for As exposure from combined ingestion and dermal contact pathways exceeded the safe level of 1.0 for both adults and children, indicated potential non-carcinogenic health risks. The total cancer risk induced by groundwater As exceeded the acceptable limit of 1 × 10–4. Sensitivity analysis highlighted exposure duration, element concentration in water, and average time as the most significant variables causing the probable health risks. Speciation modeling using PHREEQC highlighted the occurrence of As(V) and As(III) in groundwater of the UA. Reductive dissolution of Fe(III) (oxyhydr)oxides and clay minerals was identified as the main controlling mechanism of As mobilization. This communication emphasizes the need for appropriate approaches in mitigating toxic element contamination of water resources in coastal parts of the UA to safeguard public health from carcinogenic and non-carcinogenic risks.

Determination of total concentration and bioaccessible fraction of metals in tomatoes and their derivatives by MIP OES

This study presents information about the total concentration and bioaccessible fraction of barium (Ba), calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), lead (Pb) and zinc (Zn) in different cultivars of tomato (Gaucho, Paulista, Italiano and Cherry) and their derivatives (sauce and tomato extract). The determinations were performed by microwave induced plasma optical emission spectrometry (MIP OES). The bioaccessible fraction of the elements was evaluated through in vitro digestion process and the concentrations varied between 25 and 100 % ​for Cu, Fe, Mn and Zn, depending on the type of tomato sample and its derivatives. The total concentrations for all the elements studied were below the recommendation of dietary guidelines. For Ba, only the Italiano sample presented 22 % of bioaccessibility. For Pb, the highest percentage of bioaccessible fraction was found in sauces and tomato extracts. The elements Cd, Hg, Li and Mo presented concentrations lower than the limit of detection for the bioaccessibility method.

Hair mineral analysis in the population of students living in the Lower Silesia region (Poland) in 2019: Comparison with biomonitoring study in 2009 and literature data

The paper presents a comparative analysis of biomonitoring research results using hair mineral analysis today and 10 years ago. The aim of the present work was to examine the impact of individual factors, on the content of elements in human hair. The mineral analysis of 115 hair samples was carried out using ICP-OES and AAS technique. It was shown that calcium, barium, copper, mercury, magnesium, manganese and selenium content depend on gender and is higher for women. Statistically significant synergistic correlations were identified between the following pairs of elements: (Ca–Mg), (P–S), (Mo–Sb) and (Ba–Pb). The results of the present work were compared with the previous assessment in 2009 on students of the same age. The content of most of the heavy metals in hair was reduced significantly, which is a sign of the improving state of the local environment. The greatest decrease was recorded for silver (96.6%), arsenic (93.4%), mercury (45.1%), lead (67.7%), antimony (55.2%), thallium (10 times) and cobalt (93.7%). The level of the following elements increased: Ba: 27.3%, Cu: 28.5%, Ni: 22.4%, Ti: 191%, Zn: 11.0%. Changes in the content of most heavy metals in hair have been noted, as well as changes of reference ranges, which may indicate an improvement in the state of the environment in Wrocław, Lower Silesia (Poland) over the last 10 years. These results were confirmed by biomonitoring studies carried out with human hair, which was shown to be a reliable biomarker of human exposure to toxic elements.

Micro- and Ultramicroelemental Content in Otoliths of Blue Antimora Antimora rostrata and Pacific Flatnose A. microlepis (Moridae, Teleostei)

The content of 53 micro- and ultramicroelements in otoliths of two deep-sea fish species, blue antimora Antimora rostrata from the Northwest Atlantic (NWA) and Pacific flatnose Antimora microlepis from the Northeast Pacific (NEP), is studied. The otoliths of these species were characterized by the maximum concentration of strontium, nickel, zinc, barium, chromium, copper, lithium, cobalt, and zirconium (in descending order). The content of barium, tungsten, and lithium was higher in otoliths of the former species, while that of yttrium and uranium, in otoliths of the latter. This is probably due to differences in the chemical composition of NWA and NEP waters, as well as to differences in the linear size of fishes and changes in the concentrations of individual elements during ontogeny. The lead, arsenic, zinc, copper, and nickel contents in the otoliths, kidneys, muscles, and liver of fishes from different areas are compared.

Exposure to heavy metals in utero and autism spectrum disorder at age 3

Background: Autism spectrum disorder is a prevalent and heterogeneous neurodevelopmental disorder. Risk is attributed to genetic and prenatal environmental factors, though the environmental agents are incompletely characterized.Methods: In the Early Autism Risk Longitudinal Investigation (EARLI), an enriched-risk pregnancy cohort, maternal urinary metals concentrations at two time points during pregnancy were measured using inductively coupled plasma mass spectrometry. At age three, clinicians assessed autism spectrum disorder with DSM-5 criteria. Using multivariable logistic regression, we tested each metal for association with autism spectrum disorder status, adjusting for gestational age, child sex, and maternal education.Results: In this enriched-risk study sample (n=167), 18.6% of children were diagnosed with autism spectrum disorder, 31.1% were non-neurotypical, and 50.9% were males. Mothers averaged 34 years old and 57.5% had greater than high school education. Median urinary metals concentrations were 0.04 ppb antimony, 6.8 ppb arsenic, 1.8 ppb barium, 0.12 ppb cadmium, 3.9 ppb cesium, 0.66 ppb cobalt, 8.5 ppb copper, 0.26 ppb lead, 0.26 ppb manganese, 0.22 ppb mercury, 51.8 ppb molybdenum, 3.5 ppb nickel, 39 ppb selenium, 0.14 ppb thallium, 0.37 ppb tin, and 245 ppb zinc. In early pregnancy, an interquartile range increase in barium concentration was associated with 2.33 (1.13, 4.82) higher odds of autism spectrum disorder, an interquartile range increase of cesium with 2.65 (1.37,5.13) higher odds, and an interquartile range increase in zinc with 2.11 (1.21, 3.69) higher odds. Having cadmium concentration over the level of detection was associated with 2.78 (1.02, 7.59) higher odds of autism spectrum disorder. Longitudinal analyses and mixtures analyses will be presented.Conclusion: Exposure in utero to elevated metals levels (barium, cesium, cadmium, zinc), as measured via maternal urine, was associated with increased odds of developing autism spectrum disorder. Prenatal timing of exposure and longitudinal clinical evaluations are critical.

Characteristics of inorganic matter from Australian municipal solid waste processed under combustion and gasification conditions.

The presence and composition of ash in solid waste streams produced by the thermochemical processes can affect the further disposal or use of the waste. This study characterised the chemical species, mineralogy and trace element mobilisation in laboratory-produced ashes arising from different municipal solid waste (MSW) streams processed under reducing and oxidising atmospheres.The composition of cumulative ash samples produced under oxidising conditions was very similar to the composition of the industrial bottom ash samples produced during MSW incineration. We identified differences in mineral phase compositions and in some trace element concentrations of ashes produced under combustion and gasification conditions. Differences in concentrations of boron, barium, cadmium, chromium, copper, chlorine, molybdenum, antimony, lead, thorium and zinc in ashes associated with different MSW streams were also observed. On the basis of the concentrations of trace elements in ashes, we evaluated each MSW stream in terms of potential management strategies and use of the mineral matter remaining after combustion and gasification. Most of ashes produced from MSW can be at least classified as Class IV (secure) waste according to an Australian standard regulation guideline.

Association of plasma trace element levels with neovascular age-related macular degeneration

Although the triggers causing angiogenesis in the context of neovascular age-related macular degeneration (nAMD) are not fully understood, oxidative stress is likely involved. Oxidative stress in the eye can occur through exposure of macular tissues to sunlight and local or systemic exposure to oxidative stressors associated with environmental or lifestyle factors. Because trace elements have been implicated as regulators of oxidative stress and cellular antioxidant defense mechanisms, we hypothesized that they may play a role as a risk factor, modifying the progression toward nAMD.Herein, we determined whether levels of human plasma trace elements are different in 236 individuals with nAMD compared to 236 age-matched controls without AMD. Plasma levels of 16 trace elements including arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, lead, antimony, selenium, vanadium and zinc were measured using inductively coupled plasma mass spectrometry. Associations of trace elements with demographic, environmental and lifestyle factors and AMD-associated genetic variants were assessed.Elevated levels of barium and cadmium and reduced levels of chromium were observed in nAMD patients compared to controls. Mean plasma concentrations of barium were 1.35 μg/L (standard deviation [SD] 0.71) in nAMD and 1.15 μg/L (SD 0.63) in controls (P = 0.001). Mean levels of chromium were 0.37 μg/L (SD 0.22) in nAMD and 0.46 μg/L (SD 0.34) in controls (P = 0.001). Median levels for cadmium, which were not normally distributed, were 0.016 μg/L (interquartile range [IQR] 0.001–0.026) in nAMD and 0.012 μg/L (IQR 0.001–0.022) in controls (P = 0.002). Comparison of the Spearman's correlation coefficients between nAMD patients and controls identified a difference in correlations for 8 trace elements. Cadmium levels were associated with the smoking status (P < 0.001), while barium levels showed a trend of association with the usage of antihypertensive drugs. None of the AMD-associated genetic variants were associated with any trace element levels.In conclusion, in this case-control study we detected elevated plasma levels of barium and cadmium and reduced plasma levels of chromium in nAMD patients. An imbalance in plasma trace elements, which is most likely driven by environmental and lifestyle factors, might have a role in the pathogenesis of AMD. These trace elements may be incorporated as biomarkers into models for prediction of disease risk and progression. Additionally, population-based preventive strategies to decrease Cd exposure, especially by the cessation of smoking, could potentially reduce the burden of nAMD. Future studies are warranted to investigate whether supplementation of Cr would have a beneficial effect on nAMD.

Geochemical and geophysical indicators of oil and gas wastewater can trace potential exposure pathways following releases to surface waters

Releases of oil and gas (OG) wastewaters can have complex effects on stream-water quality and downstream organisms, due to sediment-water interactions and groundwater/surface water exchange. Previously, elevated concentrations of sodium (Na), chloride (Cl), barium (Ba), strontium (Sr), and lithium (Li), and trace hydrocarbons were determined to be key markers of OG wastewater releases when combined with Sr and radium (Ra) isotopic compositions. Here, we assessed the persistence of an OG wastewater spill in a creek in North Dakota using a combination of geochemical measurements and modeling, hydrologic analysis, and geophysical investigations. OG wastewater comprised 0.1 to 0.3% of the stream-water compositions at downstream sites in February and June 2015 but could not be quantified in 2016 and 2017. However, OG-wastewater markers persisted in sediments and pore water for 2.5 years after the spill and up to 7.2-km downstream from the spill site. Concentrations of OG wastewater constituents were highly variable depending on the hydrologic conditions. Electromagnetic measurements indicated substantially higher electrical conductivity under the bank adjacent to a seep 7.2 km downstream from the spill site. Geomorphic investigations revealed mobilization of sediment is an important contaminant transport process. Labile Ba, Ra, Sr, and ammonium (NH4) concentrations extracted from sediments indicated sediments are a long-term reservoir of these constituents, both in the creek and on the floodplain. Using the drivers of ecological effects identified at this intensively studied site we identified 41 watersheds across the North Dakota landscape that may be subject to similar episodic inputs from OG wastewater spills. Effects of contaminants released to the environment during OG waste management activities remain poorly understood; however, analyses of Ra and Sr isotopic compositions, as well as trace inorganic and organic compound concentrations at these sites in pore-water provide insights into potentials for animal and human exposures well outside source-remediation zones.

The diverse metal composition of plastic items and its implications

Plastic items from urban, freshwater and marine environments as well as from household items and electric supplies were analyzed for their metals and metalloids arsenic, barium, bismuth, cadmium, cobalt, chromium, copper, manganese, nickel, iron, lead, antimony, tin and zinc. Total metal contents ranged from 3 μg/kg (5th percentile) up to 7 g/kg (95th percentile). The median content of most metals was below 1 mg/kg and did not exceed legal limits. Iron and zinc were the metals with the highest contents, with medians of approximately 50 mg/kg. Multivariate statistics (k-means clustering and principal component analysis) did not reveal a polymer specific metal composition except for samples of tire tread rubber that was obtained from passenger car tires. Investigation on the potential origin of the metals in plastics revealed that pigments were the most likely source. In comparison to natural and anthropogenic materials in rivers, oceans and air, the metal content of plastic items was within the same order of magnitude, except for antimony and zinc contents. Literature data on the adsorption capacities of plastics suggested that the inherent content of barium, iron, antimony and zinc was dominating the total content in the studied samples. Compared to suspended sediments in rivers, the metal flux into marine environment transported with plastic items was found to be negligible due to the three orders of magnitude lower masses. The different properties, however, may consequently lead to the transport of plastics and their constituents into pristine and remote environments which natural particulate matter may not reach.

Effects of light on the Ba/Ca ratios in coral skeletons

The ratios of barium to calcium (Ba/Ca) in reef coral skeletons have been used as a proxy to reconstruct temporal change in barium concentration in surface ocean. To reduce the uncertainty of the coral Ba/Ca proxy, the Ba distribution coefficients between seawater and coral skeletons were determined under different light conditions. Coral planulae (Acropora tenuis) were metamorphosed and settled in dishes with commercial peptide Hym-248 in the laboratory. Juvenile corals were infected with symbiotic algae (Durusdinium sp.) and cultured in 5 Ba concentrations (5, 10, 20, 35, and 150 μmol/mol) for 2 months. Half of the dishes were placed under low light conditions (10–33 μmol m-2 s−1), and another half of the dishes were placed under high light conditions (67–84 μmol m-2 s−1). The Ba/Ca ratios in the coral skeletons were highly correlated with those in ambient seawater under both high and low conditions (R2 > 0.8). The Ba distribution coefficients between seawater with 5–35 μmol/mol of Ba concentration and coral skeletons were 0.72 and 2.83 under high and low light conditions, respectively. These results suggest that biological processes related to light availability could influence to Ba/Cacoral.

Enhancement of photocatalytic activity of BiVO4 by barium doping

BiVO4 was successfully synthesized by solid state method and doped by barium in the sites of bismuth in 3%, 6%, 9% and 15% to form Bi0.97Ba0.03VO4, Bi0.94Ba0.06VO4, Bi0.91Ba0.09VO4 and Bi0.85Ba0.15VO4 respectively. The products were characterized using powder X-ray diffraction, diffuse reflectance spectroscopy, scanning electron microscopy and photoluminescence spectroscopy. The band gap of undoped BiVO4 was calculated to be 2.19 eV and the barium doped BiVO4 compounds exhibit band gaps which are closer to the band gap of undoped compound. The photocatalytic activities of undoped and doped catalysts for the degradation of methylene blue were studied using UV-Visible spectroscopy and found to be depended largely on the barium content and the particle size of the compounds.