Abundance Of Mercury Research Articles

Detection of the Hg ii Line at 3983.93 Å in One Optical Spectrum of Maia

Abstract Evidence is reported for the first time for the presence of the Hg ii line in a Narval I profile of Maia, the fourth brightest member of the Pleiades open cluster. The Hg ii line in Maia absorbs about 2% of the local continuum and can be reproduced with an overabundance of mercury of about 4000 times the solar mercury abundance. This line is probably variable suggesting that mercury might be distributed in spot(s) over the surface of Maia. Maia is currently classified as a He-weak Mn star, it should probably be reclassified as a HgMn star.

Evidence of vertical abundance stratification in the SB1 star HD 161660: a new HgMn

ABSTRACT In this paper, we present a detailed spectroscopic study of the SB1 system HD 161660. New spectroscopic observations have been obtained by us with Catania Astrophysical Observatory Spectropolarimeter (CAOS@OAC). Combining these observations with archive data from HARPS@3.6ESO, we derived atmospheric parameters as temperature and gravity (from the fit of Balmer lines), microturbulence and rotational velocity (from metal lines), and chemical composition. We found underabundances of helium, carbon, magnesium, sulphur and chromium, overabundances of neon, phosphorus, argon, manganese, xenon, and mercury. All other elements have solar composition. In particular, mercury abundance is derived taking into account an isotopic mixture different from the terrestrial one (essentially pure 202Hg). Considering this chemical pattern, we definitively confirm HD 161660 is an HgMn star. Further, variability of equivalent widths points out a non-homogeneous distribution of helium and magnesium over stellar surface. As to iron and phosphorus, we found a non-constant abundance with the optical depth, a result currently considered an evidence of vertical stratification. Finally, we improved the fundamental parameters characterizing the HD 161660 orbit.

The Abundances of Aluminum and Mercury of β Scl derived from its far Ultraviolet Spectrum

The Abundances of Aluminum and Mercury of β Scl derived from its far Ultraviolet Spectrum

The Abundance of Mercury in HR 6096 A

The Abundance of Mercury in HR 6096 A

Ecological passportization of urban population in the Northwest Russia

The paper presents important criteria for human health estimation in urbanized industrial areas. On the contrary, environmental and economic conditions are successfully identified on the basis of population’ elemental status. Cause-effect relations between micro and macro element consumption (lack or abundance) and public health in North-West Federal District of the Russian Federation have been established using the open press sources. Data capturing and visualization are made. Spatial digital maps presenting element consumption for non-personalized groups as well as their main disorders are obtained. The environmental situation in urbanized regions should be used to make future modeling possible for the purposes of a green economy. The paper demonstrates there al picture of availability of macro and micro elements, their lack or abundance. Maximum disease cases per 1000 people appear in the Republic of Karelia, and minimum is in the Leningradskaya Oblast. In practice, mercury abundance is a stimulating agent for most disorders of different origin, which primarily, for example, neoplasms and leukemia. Monitoring and correction of chronic toxic metal exposure at the individual and population levels can significantly reduce expenses on educational and medical services, increase labor efficiency.

Interpretation of regional-scale distribution of high Hg in soils of karst area in southwest China

The abundance and spatial distribution of mercury in soil samples covering nearly the whole of China ( c . 9 million km 2 ) were obtained by the China Geochemical Baseline (CGB) project from 2008 to 2015. From the data and maps, it was found that the Hg contents both in the top (0–25 cm) and deep soil (below 100 cm or C-horizon) of the karst area in southwestern China are richer than that of any other geographical landscape areas. Median Hg values for this karst area are 113 and 90 µg/kg respectively ( n = 126), in the top and bottom soils, much higher than the corresponding data of 26 and 18 µg/kg for the entire country ( n = 3380). This regional-scale high Hg distribution is due mainly to high Hg geochemical backgrounds in bedrock and soil formation on limestone. A large-scale epithermal metallogenic domain developed in southwestern China and the extensive distribution of Lower Cambrian black shale in southwest China led to a high Hg geochemical background for parent rocks of soils. The chemical weathering of carbonate minerals and the geochemical behaviour of Hg in the epigenetic environment result in Hg enrichment by ferric oxides, iron hydroxide and organic carbon in limestone soils. Human activities mostly result in local-scale Hg anomalies, but have little effect on this regional-scale anomaly.

The abundance and speciation of mercury in the Adriatic plankton, bivalves and fish – a review

This article presents an overview of available research on mercury speciation in the most studied biota of the Adriatic Sea as a specific biogeochemical subunit of the Mediterranean. We present current knowledge about mercury concentration, speciation, spatial distribution and temporal changes in plankton, bivalves and fish from the Adriatic Sea. Results from mercury speciation studies in marine organisms are used to describe the extent of mercury bioaccumulation in the Adriatic Sea. Mercury biogeochemical cycle in the Adriatic is characterised by increased mercury concentrations from the water column, through plankton, bivalves and smaller fish to predator fish species. Although the Adriatic Sea has the highest mercury concentration in the whole Mediterranean Sea, fish species at the higher trophic levels have similar mercury concentrations everywhere in the Mediterranean, indicating incomplete understanding of the transfer mechanisms of mercury from seawater to upper trophic levels. As consumption of (contaminated) food is the main route of human exposure to mercury, it is of great importance to understand the influence of mercury contamination in the Adriatic Sea.

Cigarette butts abundance and association of mercury and lead along the Persian Gulf beach: an initial investigation.

The toxic metal contents of cigarette butts and distribution of cigarette butts have not been studied well in maritime environment. In the present study, cigarette butts distribution and the associations of Hg and Pb from cigarette butts were monitored along the Persian Gulf with 10days interval sampling time. The number of cigarette butts, and Hg and Pb associations of butts were found to vary widely between 2 and 38 items per square meter, 2.5 and 86.32ng/g cigarette butt (CB), as well as 650 and 8630ng/g CB, respectively. Wilcoxon signed-rank test showed that there were no significant differences between the number of butts, and Hg and Pb contents of the butts at different sampling times. Considering amount of cigarette butts littered yearly, this study demonstrates that remarkable toxic metals of Hg and Pb may enter maritime environment each year and may introduce critical hazards to aquatic organisms, enter food chain, and finally human body.

Mercury spikes suggest volcanic driver of the Ordovician-Silurian mass extinction

The second largest Phanerozoic mass extinction occurred at the Ordovician-Silurian (O-S) boundary. However, unlike the other major mass extinction events, the driver for the O-S extinction remains uncertain. The abundance of mercury (Hg) and total organic carbon (TOC) of Ordovician and early Silurian marine sediments were analyzed from four sections (Huanghuachang, Chenjiahe, Wangjiawan and Dingjiapo) in the Yichang area, South China, as a test for evidence of massive volcanism associated with the O-S event. Our results indicate the Hg concentrations generally vary in parallel with TOC, and that the Hg/TOC ratios remain low and steady state through the Early and Middle Ordovician. However, Hg concentrations and the Hg/TOC ratio increased rapidly in the Late Katian, and have a second peak during the Late Hirnantian (Late Ordovician) that was temporally coincident with two main pulses of mass extinction. Hg isotope data display little to no variation associated with the Hg spikes during the extinction intervals, indicating that the observed Hg spikes are from a volcanic source. These results suggest intense volcanism occurred during the Late Ordovician, and as in other Phanerozoic extinctions, likely played an important role in the O-S event.

The abundance, distribution and speciation of mercury in waters and sediments of the Adriatic Sea

This review focuses on mercury speciation in the Adriatic Sea, a marginal sea of the Mediterranean, which represents its distinct biogeochemical subunit due to anthropogenic mercury loadings. The current knowledge about mercury cycling in the Adriatic is presented through an overview of the state of the art of research in this area: temporal and spatial distributions and occurrence of mercury species in seawater and sediment, and chemical transformations. We summarised research results of mercury speciation in order to describe its presence and fate in the Adriatic Sea. The Adriatic Sea represents a net source of mercury to the Mediterranean Sea due to the highest total mercury concentrations observed in the North Adriatic Sea and the highest methylmercury concentrations in the South Adriatic Pit. However, the biogeochemical cycle of mercury is not completely known and our understanding of mercury transport between compartments and its (bio)transformations is limited. Future research needs to focus on microbial and chemical processes of mercury transformations to improve our understanding of the impacts of mercury contamination on the environment and human health in the Adriatic Sea.

Formation of Nanocolloidal Metacinnabar in Mercury-DOM-Sulfide Systems

Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., <4 nmol Hg (mg DOM)(-1)) by combining solid phase extraction using C(18) resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C(18) resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury-sulfur bonds with a longer interatomic distance (2.51-2.53 Å) similar to the mercury-sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg(-1)) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to be considered when addressing mercury biogeochemistry.

Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys

During its three flybys of Mercury, the MESSENGER spacecraft made the first detection of gamma-ray emission from the planet's surface. With a closest approach distance of ∼200 km, the flybys provided an opportunity to measure elemental abundances of Mercury's near-equatorial regions, which will not be visited at low altitude during MESSENGER's orbital mission phase. Despite being limited by low planetary photon flux, sufficient counts were accumulated during the first two flybys to estimate bounds on abundances for some elements having relatively strong gamma-ray spectral peaks, including Si, Fe, Ti, K, and Th. Only for Si is the standard deviation σ sufficiently small to conclude that this element was detected with 99% confidence. Iron and potassium are detected at the 2− σ (95% confidence) level, whereas only upper bounds on Ti and Th can be determined. Relative to a Si abundance assumed to be 18 weight percent (wt%), 2− σ upper bounds have been estimated as 9.7 wt% for Fe, 7.0 wt% for Ti, 0.087 wt% for K, and 2.2 ppm for Th. The relatively low upper bound on K rules out some previously suggested models for surface composition for the regions sampled. Upper bounds on Fe/Si and Ti/Si ratios are generally consistent with Ti and Fe abundances estimated from the analysis of measurements by the MESSENGER Neutron Spectrometer during the flybys but are also permissive of much lower concentrations.

Mercury surface composition: Integrating petrologic modeling and remote sensing data to place constraints on FeO abundance

A significant opaque component in Mercury’s crust is inferred based on albedo and spectral observations. Previous workers have favored iron–titanium bearing oxide minerals as the spectrally neutral opaque. A consequence of this hypothesis is that Mercury’s surface would have a high FeO content. An array of remote sensing techniques have not provided definitive constraints on the FeO content of Mercury’s surface. However, spectral observations have not detected a diagnostic 1 μm absorption band and have thus limited the FeO in coexisting silicates to <2 wt.% FeO. In this paper, we assess equilibrium among oxide and silicate minerals to constrain the distribution of iron between opaque oxides and silicates under a variety of environmental conditions. Equilibrium modeling is favored here because the geologic process that produced Mercury’s low-albedo intermediate terrain must have occurred globally, which favors a common widespread igneous process. Based on our modeling, we find that iron-rich ilmenite cannot occur with silicates that do not display a 1 μm absorption feature unless plagioclase abundances are high. However, such high plagioclase abundances are precluded by Mercury’s low albedo. Incorporating equilibrium crystallization modeling with spectral and albedo constraints we find the iron abundance of Mercury’s intermediate terrain is ⩽10 wt.% FeO. This intermediate iron composition matches constraints provided by visible albedo and total neutron absorption observed by MESSENGER. In fact, the total neutron absorption of mixtures of oxide, plagioclase, olivine and pyroxene for the oxide abundances estimated for Mercury, favor Mg-rich members of the ilmenite–geikielite solid-solution series. This work offers compositional constraints for Fe, Ti, and Mg that will be testable by various MESSENGER instrument data sets after it begins its orbital mission.

HD 65949: the highest known mercury excess of any CP star?

ESO spectra of HD 65949 show it to be unlike any of the well-known types within its temperature range $\approx$ 13600K. It is neither a silicon, nor a mercury-manganese star, though it has a huge Hg II line at $\lambda$3984. We estimate $\log({\rm Hg/H}) + 12.0 \approx 7.4$. This is higher than any published stellar mercury abundance. HD 65949 is a member of a nearby open cluster, NGC 2516, which is only slightly older than the Pleiades, and has been of recent interest because of its numerous X-ray emission stars, including HD 65949 itself, or a close companion. A longitudinal magnetic field of the order of -290 Gauss at the 4.7~$\sigma$ level was very recently diagnosed from accurate circular spectropolarimetric observations with FORS 1 at the VLT. The spectral lines are sharp, allowing a thorough identification study. Second spectra of Ti, Cr, and Fe are rich. Mn II is well identified but not unusually strong. Numerous lines of S II and P II are found, but not Ga II. The resonance lines of Sr II are strong. While many Y II lines are identified, and Nb II is very likely present, {\it no} Zr II lines were found. Xe II is well identified. Strong absorptions from the third spectra of the lanthanides Pr, Nd, and Ho are present, but lines from the second spectra of lanthanides are extremely weak or absent. Among lines from the heavier elements, those of Pt II are clearly present, and the heaviest isotope, $^{198}$Pt, is indicated. The uncommon spectrum of Re II is certain, while Os II and Te II are highly probable. Several of the noted anomalies are unusual for a star as hot as HD 65949.

The abundance and source of mercury-binding organic ligands in Long Island Sound

The abundance and strength of mercury (Hg)-complexing organic matter was measured in samples collected from Long Island Sound (LIS) and related locations. A range in ligand-equivalent concentrations was found in LIS (0.3–6 nN). Rivers, lakes, sewage effluent, and marine porewaters were also sampled. When the ligand concentrations were normalized to dissolved organic carbon (DOC) concentrations, the samples fell into broad groups. Offshore and sewage effluent samples were relatively ligand-poor, while river, lake, and porewater samples were ligand-rich. Normalized ligand abundance in LIS water was intermediate. A first-order mass balance for ligand and DOC suggests that terrestrial organic matter and phytoplankton exudates are the dominant sources of ligand to LIS, while tidal exchange and an unknown term are the dominant sinks. Concentration distributions through the Connecticut River (CTR) estuary suggest pseudo-conservative mixing of the ligand derived from the Connecticut River watershed. The identity of the material is unknown, but ligand-to-DOC ratios are well below the ratio of bulk reduced sulfur to DOC.

On the elemental abundance and isotopic mixture of mercury in HgMn stars

Optical region spectra of 31 HgMn stars have been studied for the abundance and isotope mixture of mercury. In the course of the investigation the lines Hg  λ4358 and Hg  λλ3984,6149 have been studied, with abundances established for all three lines in several HgMn stars. The mercury isotope mixture has been determined from high resolution spectra of the λ3984 line. Possible signs of an ionization anomaly have been detected by the comparison of the abundance derived from the Hg  line and the Hg  lines in seven of the observed HgMn stars. A possible correlation of the mercury abundance with Teff has been detected. Possible signs of a weak anticorrelation of the manganese and mercury abundance in HgMn stars have been found, which could be interpreted as a sign of inhomogeneous surface distribution of these elements. For a number of the HgMn stars in this study the mercury abundance and isotope mixture are reported for the first time.

Pulsational and rotational line profile variations of the roAp stars α Cir and HR 3831

We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. In particular, we extend the method of Doppler imaging to the analysis of spectra in the four Stokes parameters, making it possible to derive detailed and reliable stellar magnetic maps simultaneously with the imaging chemical inhomogeneities.The magnetic Doppler imaging is applied to study of magnetic topologies and distributions of chemical elements in the peculiar stars α2 CVn and 53 Cam. We found that the magnetic field geometry of 53 Cam is considerably more complex than a low-order multipolar topology, commonly assumed for magnetic A and B stars. Our Doppler imaging analysis also led to a discovery and study of spots of enhanced mercury abundance in the atmosphere of α And, a star where the presence of a global magnetic field is unlikely.The ESO 3.6-m telescope is used to collect unique, very high spectral- and time-resolution observations of rapidly oscillating peculiar A (roAp) stars and to reveal line profile variations due to stellar pulsations. We present a detailed characterization of the spectroscopic pulsational behaviour and demonstrate a remarkable diversity of pulsations in different spectral lines. The outstanding variability of the lines of rare-earth elements is used to study propagation of pulsation waves through the stellar atmospheres and identify pulsation modes. This analysis led to a discovery of a non-axisymmetric character of pulsations in roAp stars.Our study of chemical stratification in the atmosphere of the roAp star γ Equ provides a compelling evidence for significant variation of the chemical composition with depth. We find a combined effect of extreme chemical anomalies and a growth of pulsation amplitude in the outermost atmospheric layers to be the most likely origin of the high-amplitude pulsational variations of the lines of rare-earth elements.Observations of cool magnetic CP stars are obtained with the ESO Very Large Telescope and are used for empirical investigation of the anomalies in the atmospheric temperature structure. We show that the core-wing anomaly of the hydrogen Balmer lines observed in some cool CP stars can be attributed to a hot layer at an intermediate atmospheric depth.

Time-resolved spectroscopy of the roAp starγEqu

We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. In particular, we extend the method of Doppler imaging to the analysis of spectra in the four Stokes parameters, making it possible to derive detailed and reliable stellar magnetic maps simultaneously with the imaging chemical inhomogeneities.The magnetic Doppler imaging is applied to study of magnetic topologies and distributions of chemical elements in the peculiar stars α2 CVn and 53 Cam. We found that the magnetic field geometry of 53 Cam is considerably more complex than a low-order multipolar topology, commonly assumed for magnetic A and B stars. Our Doppler imaging analysis also led to a discovery and study of spots of enhanced mercury abundance in the atmosphere of α And, a star where the presence of a global magnetic field is unlikely.The ESO 3.6-m telescope is used to collect unique, very high spectral- and time-resolution observations of rapidly oscillating peculiar A (roAp) stars and to reveal line profile variations due to stellar pulsations. We present a detailed characterization of the spectroscopic pulsational behaviour and demonstrate a remarkable diversity of pulsations in different spectral lines. The outstanding variability of the lines of rare-earth elements is used to study propagation of pulsation waves through the stellar atmospheres and identify pulsation modes. This analysis led to a discovery of a non-axisymmetric character of pulsations in roAp stars.Our study of chemical stratification in the atmosphere of the roAp star γ Equ provides a compelling evidence for significant variation of the chemical composition with depth. We find a combined effect of extreme chemical anomalies and a growth of pulsation amplitude in the outermost atmospheric layers to be the most likely origin of the high-amplitude pulsational variations of the lines of rare-earth elements.Observations of cool magnetic CP stars are obtained with the ESO Very Large Telescope and are used for empirical investigation of the anomalies in the atmospheric temperature structure. We show that the core-wing anomaly of the hydrogen Balmer lines observed in some cool CP stars can be attributed to a hot layer at an intermediate atmospheric depth.

Mercury in the HgMn Stars χ Lupi and HR 7775

Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in chi Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10(-14) M. yr(-1) supports a cloud of Hg III at very small optical depths. (Less)

Factor Score Mapping of Soil Trace Element Contents for the Shenzhen Area

The abundances of copper, lead, zinc, nickel, chromium, cobalt, mercury, vanadium, and manganese in eighty three surface soil samples collected from Shenzhen area were determined. The correlation among element contents and the factors affecting the contents were studied using principle component analysis. The factor scores of the first two components were analyzed as regionalized variables using variogram analysis and Kriging. The interpolated factor scores were then mapped to show the common features in spatial distribution of a set of elements with similar geochemical behavior. It was demonstrated that the spatial distribution patterns of parent material in the area are the primary factor governing the spatial variation of the elements.