Mercury profiles in sediment from the marginal high of Arabian Sea: An indicator of increasing anthropogenic Hg input

Digital Repository Service at National Institute of Oceanography (India)

Chakraborty, P.; Vudamala, K.; Chennuri, K.; Armoury, K.; Linsy, P.; Ramteke, D.; Sebastian, T.; Jayachandran, S.; Naik, C.; Naik, R.; Nath, B.N.

provided the sediments remain undisturbed by either natural or anthropogenic forces (Engstrom et al. 2007). However, it has also been suggested that early diagenesis in sediment column may increase mobility of Hg and can alter concentration profile of Hg... the mobility of Hg in sediment (Dehairq 1989; Gagnon and Mucci 1997; van der Zee and van Raaphorst 2004; Konovalov et al. 2007). Oxidation of sedimentary organic matter also appears to release significant amounts of mercury (associated with organic phase...

Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.

Science.gov (United States)

Luo, Hong-Wei; Yin, Xiangping; Jubb, Aaron M; Chen, Hongmei; Lu, Xia; Zhang, Weihua; Lin, Hui; Yu, Han-Qing; Liang, Liyuan; Sheng, Guo-Ping; Gu, Baohua

2017-01-01

Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Transformational Approach to Parametric Accumulated-Cost Static Profiling

DEFF Research Database (Denmark)

Haemmerlé, Rémy; López García, Pedro; Liqat, Umer

2016-01-01

Traditional static resource analyses estimate the total resource usage of a program, without executing it. In this paper we present a novel resource analysis whose aim is instead the static profiling of accumulated cost, i.e., to discover, for selected parts of the program, an estimate or bound...... of the resource usage accumulated in each of those parts. Traditional resource analyses are parametric in the sense that the results can be functions on input data sizes. Our static profiling is also parametric, i.e., our accumulated cost estimates are also parameterized by input data sizes. Our proposal is based...... on the concept of cost centers and a program transformation that allows the static inference of functions that return bounds on these accumulated costs depending on input data sizes, for each cost center of interest. Such information is much more useful to the software developer than the traditional resource...

Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species

International Nuclear Information System (INIS)

Greger, Maria; Wang Yaodong; Neuschuetz, Clara

2005-01-01

In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 μg L -1 Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. - Mercury translocation to shoots was low

Pulmonary scintigraphy using 197HgCl2 and pulmonary perfusion scintigraphy in bronchopulmonary diseases

International Nuclear Information System (INIS)

Fujii, Tadashige; Kanai, Hisakata; Handa, Kenjiro; Kusama, Shozo

1981-01-01

75 patients with pulmonary tuberculosis and 106 patients with bronchopulmonary diseases whose chest x-rays showed diffuse shadows were studied. Pulmonary scintigraphy using 197 HgCl 2 was useful for the diagnosis of the localization and the activity of pulmonary tuberculosis, because 197 HgCl 2 readily accumulated in the foci, and its accumulation rate was related to the activity of the foci. 197 HgCl 2 also accumulated markedly in foci of pneumoconiosis, especially, in areas showing large shadows and foci suspected to be tuberculosis. 197 HgCl 2 also accumulated in areas of chronic bronchitis, diffuse interstitial pneumonia and bronchiectasis. Its accumulation was considered to have a relation to the activity of inflammation. In primary pulmonary carcinoma, 197 HgCl 2 accumulated most markedly, in the primary lesions. 197 HgCl 2 also accumulated in metastatic or invasion areas of the hilus and the mediastinum. It accumulated in intrapulmonary metastatic foci of pulmonary carcinoma and multiple metastatic pulmonary tumors, but it was difficult to differentiate these diseases from other pulmonary diseases. In selected cases, it was useful to use pulmonary scintigraphy using 197 HgCl 2 together with pulmonary perfusion scintigraphy for the diagnosis of diffuse bronchopulmonary diseases. (Tsunoda, M.)

NAA for studying detoxification of Cr and Hg by Arthrobacter globiformis 151B

International Nuclear Information System (INIS)

Tsibakhashvili, N.; Mosulishvili, L.; Kirkesali, E.; Murusidze, I.; Frontasyeva, M.V.; Pavlov, S.S.; Zinicovscaia, I.I.

2010-01-01

Instrumental neutron activation analysis was used to study accumulation of Hg(II) and Cr(VI) ions in Arthrobacter globiformis 151B, a gram-positive, Cr(VI)-reducer aerobic bacterium isolated from basalt sample taken from the most polluted region in the Republic of Georgia (Kazreti). Experiments were focused on (1) accumulation of Hg(II) in bacterial cells; (2) accumulation of Cr(VI) in A. globiformis 151B in the presence of Hg(II) and (3) effects of Hg(II) and mixture of Cr(VI)-Hg(II) on the elemental composition of bacteria. It was shown that this bacterial strain possesses uptake mechanisms by which mercury toxicity can be reduced in environment and that accumulation of Cr(VI) in A. globiformis 151B is much higher in the presence of Hg(II) ions. Accumulation of Hg(II), similar to the Cr(VI) accumulation, follows well the Lengmuir-Freundlich model. NAA measurements showed increased content of Fe in bacteria under Hg and Cr action, suggesting that Fe-containing biomolecules play a decisive role in detoxifying of heavy metals by A. globiformis 151B. A concentration of 5000 μg/L of Hg(II) was found to be critical for A. globiformis 151B. At this concentration of Hg(II) the concentrations of both essential (Na, Mg, Al, Cl, K, Mn, Zn) and some non-essential elements (Rb, Sb, Sc, As) changed drastically along with a decrease of the biomass of bacteria by a factor of two. One may assume that under this high exposure to Hg(II) the structure of the bacterial cell wall was destroyed. (author)

Field controlled experiments of mercury accumulation in crops from air and soil

Energy Technology Data Exchange (ETDEWEB)

Niu Zhenchuan [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Zhang Xiaoshan, E-mail: zhangxsh@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Wang Zhangwei, E-mail: wangzhw@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Ci Zhijia [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)

2011-10-15

Field open top chambers (OTCs) and soil mercury (Hg) enriched experiments were employed to study the influence of Hg concentrations in air and soil on the Hg accumulation in the organs of maize (Zea mays L.) and wheat (Triticum aestivum L.). Results showed that Hg concentrations in foliages were correlated significantly (p < 0.05) with air Hg concentrations but insignificantly correlated with soil Hg concentrations, indicating that Hg in crop foliages was mainly from air. Hg concentrations in roots were generally correlated with soil Hg concentrations (p < 0.05) but insignificantly correlated with air Hg concentrations, indicating that Hg in crop roots was mainly from soil. No significant correlations were found between Hg concentrations in stems and those in air and soil. However, Hg concentrations in upper stems were usually higher than those in bottom stems, implying air Hg might have stronger influence than soil Hg on stem Hg accumulation. - Highlights: > Hg accumulation in crop organs was studied by OTCs and soil Hg enriched experiments. > Hg accumulation in foliages and roots was mainly from air and soil, respectively. > Air Hg had stronger influence than soil Hg on stem Hg accumulation. > Foliar Hg concentrations showed the trend of increase over growth stages. - Capsule Mercury accumulated in the aboveground organs of crop was mainly from the air.

Field controlled experiments of mercury accumulation in crops from air and soil

International Nuclear Information System (INIS)

Niu Zhenchuan; Zhang Xiaoshan; Wang Zhangwei; Ci Zhijia

2011-01-01

Field open top chambers (OTCs) and soil mercury (Hg) enriched experiments were employed to study the influence of Hg concentrations in air and soil on the Hg accumulation in the organs of maize (Zea mays L.) and wheat (Triticum aestivum L.). Results showed that Hg concentrations in foliages were correlated significantly (p < 0.05) with air Hg concentrations but insignificantly correlated with soil Hg concentrations, indicating that Hg in crop foliages was mainly from air. Hg concentrations in roots were generally correlated with soil Hg concentrations (p < 0.05) but insignificantly correlated with air Hg concentrations, indicating that Hg in crop roots was mainly from soil. No significant correlations were found between Hg concentrations in stems and those in air and soil. However, Hg concentrations in upper stems were usually higher than those in bottom stems, implying air Hg might have stronger influence than soil Hg on stem Hg accumulation. - Highlights: → Hg accumulation in crop organs was studied by OTCs and soil Hg enriched experiments. → Hg accumulation in foliages and roots was mainly from air and soil, respectively. → Air Hg had stronger influence than soil Hg on stem Hg accumulation. → Foliar Hg concentrations showed the trend of increase over growth stages. - Capsule Mercury accumulated in the aboveground organs of crop was mainly from the air.

Total lipid accumulation and fatty acid profiles of microalga Spirulina ...

African Journals Online (AJOL)

Nutrient limitation in terms of nitrogen and phosphorus increased lipid accumulation under depleted growth in Spirulina strains. Nitrogen limitation was found more effective than phosphorus in accumulating lipid. The fatty acid profile was variable: palmitic (48%), linolenic (21%) and linoleic acids (15%) were the most ...

Antioxidative response of Lepidium sativum L. during assisted phytoremediation of Hg contaminated soil.

Science.gov (United States)

Smolinska, Beata; Szczodrowska, Agnieszka

2017-09-25

In this study, Lepidium sativum L. was used in repeated phytoextraction processes to remove Hg from contaminated soil, assisted by combined use of compost and iodide (KI). L. sativum L. is sensitive to changes in environmental conditions and has been used in environmental tests. Its short vegetation period and ability to accumulate heavy metals make it suitable for use in repeated phytoextraction. The antioxidant enzymatic system of the plant (catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and glutathione S-transferase (GST)) was analysed, to understand the effects of increasing Hg accumulation and translocation. Phytoextraction was repeated six times to decrease Hg contamination in soil, and the efficiency of each step was assessed. The results indicate that L. sativum L. is able to take up and accumulate Hg from contaminated soil. A corresponding increase in enzymatic antioxidants shows that the plant defence system is activated in response to Hg stress. Using compost and KI increases total Hg accumulation and translocation to the above-ground parts of L. sativum L. Repeating the process decreases Hg contamination in pot experiments in all variants of the process. The combined use of compost and KI during repeated phytoextraction increases the efficiency of Hg removal from contaminated soil. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioaccumulation of As, Cd, Cr, Hg(II), and MeHg in killifish (Fundulus heteroclitus) from amphipod and worm prey

Energy Technology Data Exchange (ETDEWEB)

Dutton, Jessica, E-mail: dutton.jess@gmail.com; Fisher, Nicholas S., E-mail: nfisher@notes.cc.sunysb.edu

2011-08-15

Elevated metal levels in fish are a concern for the fish themselves, their predators, and possibly humans who consume contaminated seafood. Metal bioaccumulation models often rely on assimilation efficiencies (AEs) of ingested metals and loss rate constants after dietary exposure (k{sub ef}s). These models can be used to better understand processes regulating metal accumulation and can be used to make site-specific predictions of metal concentrations in animal tissues. Fish often consume a varied diet, and prey choice can influence these two parameters. We investigated the trophic transfer of As, Cd, Cr, Hg(II), and methylmercury (MeHg) from a benthic amphipod (Leptocheirus plumulosus) and an oligochaete (Lumbriculus variegatus) to killifish (Fundulus heteroclitus) using gamma-emitting radioisotopes. Except for MeHg, AEs varied between prey type. AEs were highest for MeHg (92%) and lowest for Cd (2.9-4.5%) and Cr (0.2-4%). Hg(II) showed the largest AE difference between prey type (14% amphipods, 24% worms). For Cd and Hg(II) k{sub ef}s were higher after consuming amphipods than consuming worms. Tissue distribution data shows that Cd and Hg(II) were mainly associated with the intestine, whereas As and MeHg were transported throughout the body. Calculated trophic transfer factors (TTFs) suggest that MeHg is likely to biomagnify at this trophic step at all ingestion rates, whereas As, Cd, Cr, and Hg(II) will not. Data collected in this study and others indicate that using one prey item to calculate AE and k{sub ef} could lead to an over- or underestimation of these parameters. - Highlights: {yields} We investigated the trophic transfer of metals to killifish from amphipod and worm prey. {yields} Prey choice influences metal accumulation from the diet. {yields} Only MeHg is likely to biomagnify at this trophic step.

Phytoextraction of HG by parsley (Petroselinum crispum) and its growth responses.

Science.gov (United States)

Bibi, Asma; Farooq, Umar; Naz, Sadia; Khan, Afsar; Khan, Sara; Sarwar, Rizwana; Mahmood, Qaisar; Alam, Arif; Mirza, Nosheen

2016-01-01

The effect of mercury (Hg) on the growth and survival of parsley (Petroselinum crispum) was explored at various treatments. The plants were grown in pots having Hoagland's solution to which various Hg treatments were applied and placed under greenhouse conditions. The treatments were: no metal applied (control) and six doses of Hg as mercuric chloride for 15 days. Linear trend of Hg accumulation was noted in roots, stems, and leaves with increasing Hg treatments. The maximum Hg concentration in root, stem and leaf was 8.92, 8.27, and 7.88 at Hg treatments of 25 mg l(-1), respectively. On the whole, Hg accumulation in different plant parts was in the following order: leaves > stem > roots. Linear trend was also observed for Bioaccumulation Factor (BF) and Translocation Factor (TF) with increasing Hg concentrations in the growth medium. The highest respective BFHg and TFHg values were 9.32 and 2.02 for the Hg treatments of 25 and 50 mg l(-1). In spite of the reduced growth in the presence of Hg, the plant has phytoremediation potential. It is recommended that parsley should not be cultivated in Hg contaminated sites in order to avoid dietary toxicity.

Mercury accumulation in marine bivalves: Influences of biodynamics and feeding niche

Energy Technology Data Exchange (ETDEWEB)

Pan Ke [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong); Wang Wenxiong, E-mail: wwang@ust.hk [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong)

2011-10-15

Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope ({delta}{sup 13}C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation. - Highlights: > Significant difference in Hg accumulation and MeHg:THg ratio in different bivalves. > THg concentrations in the bivalves were generally related to the efflux rates of Hg(II). > Elimination of Hg(II) and MeHg controlled the interspecific variation in MeHg:THg ratio. > MeHg and THg concentrations reflect the interaction of Hg biodynamics and food. - The species-specific body concentrations of MeHg and THg in bivalves reflect the complicated interaction between the biodynamics of Hg(II) and MeHg and the different food sources.

Revelation of susceptibility differences due to Hg(II) accumulation in Streptococcus pyogenes against CX-AgNPs and Cefixime by atomic force microscopy.

Science.gov (United States)

Rasheed, Wasia; Shah, Muhammad Raza; Perveen, Samina; Ahmed, Shakil; Uzzaman, Sami

2018-01-01

Solution based method for the formation of chemically modified silver nanoparticles (CX-AgNPs) using Cefixime as stabilizing and reducing agent was developed. The CX-AgNPs were characterized by AFM, UV-visible, FT-IR and MALDI-TOF MS. Bactericidal efficiency of CX-AgNPs and Cefixime against Streptococcus pyogenes was evaluated. Afterwards, susceptibility differences of Streptococcus pyogenes due to accumulation of Hg(II) against CX-AgNPs and Cefixime were estimated and validated through Atomic force microscopy. Selectivity and sensitivity of CX-AgNPs against Hg(II) was evaluated in a systematic manner. The CX-AgNPs was titrated against optically silent Hg(II) which induced enhancement in the SPR band of CX-AgNPs. The increase in intensity of SPR band of CX-AgNPs was determined to be proportionate to the concentration of Hg(II) in the range of 33.3-700µM obeying linear regression equation of y = 0.125x + 8.962 with the detection limit of 0.10µM and the coefficient of determination equals to 0.985 (n = 3). The association constant Ka of CX-AgNPs-Hg(II) was found to be 386.0095mol -1 dm 3 by using the Benesi Hildebrand plot. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact assessment of mercury accumulation and biochemical and molecular response of Mentha arvensis: a potential hyperaccumulator plant.

Science.gov (United States)

Manikandan, R; Sahi, S V; Venkatachalam, P

2015-01-01

The present study was focused on examining the effect of Hg oxidative stress induced physiochemical and genetic changes in M. arvensis seedlings. The growth rate of Hg treated seedlings was decreased to 56.1% and 41.5% in roots and shoots, respectively, compared to the control. Accumulation of Hg level in both roots and shoots was increased with increasing the concentration of Hg. Superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were found to be increased with increasing the Hg concentration up to 20 mg/L; however, it was decreased at 25 mg/L Hg concentration. The POX enzyme activity was positively correlated with Hg dose. The changes occurring in the random amplification of ploymorphic DNA (RAPD) profiles generated from Hg treated seedlings included variations in band intensity, disappearance of bands, and appearance of new bands compared with the control seedlings. It was concluded that DNA polymorphisms observed with RAPD profile could be used as molecular marker for the evaluation of heavy metal induced genotoxic effects in plant species. The present results strongly suggested that Mentha arvensis could be used as a potential phytoremediator plant in mercury polluted environment.

Exotic Earthworms Decrease Cd, Hg, and Pb Pools in Upland Forest Soils of Vermont and New Hampshire USA.

Science.gov (United States)

Richardson, J B; Görres, J H; Friedland, A J

2017-10-01

Exotic earthworms are present in the forests of northeastern USA, yet few studies have documented their effects on pollutant metals in soil. The objective of this study was to identify if Cd, Hg, and Pb strong-acid extractable concentrations and pools (bulk inventories) in forest soils decreased with the presence of exotic earthworms. We compared 'Low Earthworm Abundance' (LEA) sites (≤10 g m -2 earthworms, n = 13) and 'High Earthworm Abundance' (HEA) (>10 g m -2 earthworms, n = 17) sites at five watersheds across Vermont and New Hampshire. Organic horizon Cd, Hg, and Pb concentrations were lower at HEA than LEA sites. Organic horizon and total soil pools of Cd and Hg were negatively correlated with earthworm biomass. Soil profile Cd and Hg concentrations were lower at HEA than LEA sites. Our results suggest earthworms are decreasing accumulation of Cd, Hg, and Pb in forest soils, potentially via greater mobilization through organic matter disruption or bioaccumulation.

Photosynthetic pigments and peroxidase activity of Lepidium sativum L. during assisted Hg phytoextraction.

Science.gov (United States)

Smolinska, Beata; Leszczynska, Joanna

2017-05-01

The study was conducted to evaluate metabolic answer of Lepidium sativum L. on Hg, compost, and citric acid during assisted phytoextraction. The chlorophyll a and b contents, total carotenoids, and activity of peroxidase were determined in plants exposed to Hg and soil amendments. Hg accumulation in plant shoots was also investigated. The pot experiments were provided in soil artificially contaminated by Hg and/or supplemented with compost and citric acid. Hg concentration in plant shoots and soil substrates was determined by cold vapor atomic absorption spectroscopy (CV-AAS) method after acid mineralization. The plant photosynthetic pigments and peroxidase activity were measured by standard spectrophotometric methods. The study shows that L. sativum L. accumulated Hg in its aerial tissues. An increase in Hg accumulation was noticed when soil was supplemented with compost and citric acid. Increasing Hg concentration in plant shoots was correlated with enhanced activation of peroxidase activity and changes in total carotenoid concentration. Combined use of compost and citric acid also decreased the chlorophyll a and b contents in plant leaves. Presented study reveals that L. sativum L. is capable of tolerating Hg and its use during phytoextraction assisted by combined use of compost and citric acid lead to decreasing soil contamination by Hg.

Hg and Pt-metals in meteorite carbon-rich residues - Suggestions for possible host phase for Hg

Science.gov (United States)

Jovanovic, S.; Reed, G. W., Jr.

1980-01-01

Carbon-rich and oxide residual phases have been isolated from Allende and Murchison by acid demineralization for the determination of their Hg, Pt-metal, Cr, Sc, Co, and Fe contents. Experimental procedures used eliminated the possibility of exogenous and endogenous contaminant trace elements from coprecipitating with the residues. Large enrichments of Hg and Pt-metals were found in Allende but not in Murchison residues. Hg-release profiles from stepwise heating experiments suggest a sulfide as the host for Hg. Diffusion calculations for Hg based on these experiments indicate an activation energy of 7-8 kcal/mol, the same as that for Hg in troilite from an iron meteorite. This is further support for a sulfide host phase for Hg. Equilibration of Hg with this phase at approximately 900 K is indicated. Reasons for the presence of Pt-metals in noncosmic relative abundances are explored.

Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

Science.gov (United States)

Drott, A.; Skyllberg, U.

2007-12-01

Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input/output processes. In this study, the main controls on Hg methylation rates and total concentrations of MeHg, were investigated at eight sites in Sweden with sediments that had been subjected to local Hg contamination either as Hg(0), or as phenyl-Hg. Sediments were selected to represent a gradient in total Hg concentration, temperature climate, salinity, primary productivity, and organic C content and quality. Most sediments were high in organic matter content due to wood fibre efflux from pulp and paper industry. The pore water was analysed for total Hg, MeHg, DOC, H2S(aq), pH, DOC, Cl and Br. The chemical speciation of Hg(II) and MeHg in pore water was calculated using equilibrium models. Potential methylation and demethylation rates in sediments were determined in incubation experiments at 23° C under N2(g) for 48 h, after addition of isotopically enriched 201Hg(II) and Me204Hg. In all surface (0-20 cm) sediments there was a significant (pdetermined specific potential methylation rate constant (Km, day-1) and % MeHg (concentrations of MeHg normalized to total Hg) in the sediment. This indicates that MeHg production overruled degradation and input/output processes of MeHg in surface sediments, and that % MeHg in surface sediments may be used as a proxy for net production of MeHg. To our knowledge, these are the first data showing significant positive relationships between short term (48 h) MeHg production and longer term accumulation of MeHg, across a range of sites with different properties (1). If MeHg was not normalized to total Hg, the relationship was not significant. For sub-sets of

Magnetospectroscopy of double HgTe/CdHgTe quantum wells

Energy Technology Data Exchange (ETDEWEB)

Bovkun, L. S.; Krishtopenko, S. S.; Ikonnikov, A. V., E-mail: antikon@ipmras.ru; Aleshkin, V. Ya.; Kadykov, A. M. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Ruffenach, S.; Consejo, C.; Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221 and UM (France); Orlita, M.; Piot, B.; Potemski, M. [Laboratoire National des Champs Magnetiques Intenses (LNCMI-G), CNRS-UJF-UPS-INSA (France); Mikhailov, N. N.; Dvoretskii, S. A. [Russian Academy of Sciences, Siberian Branch, Rzhanov Institute of Semiconductor Physics (Russian Federation); Gavrilenko, V. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-11-15

The magnetoabsorption spectra in double HgTe/CdHgTe quantum wells (QWs) with normal and inverted band structures are investigated. The Landau levels in symmetric QWs with a rectangular potential profile are calculated based on the Kane 8 × 8 model. The presence of a tunnel-transparent barrier is shown to lead to the splitting of states and “doubling” of the main magnetoabsorption lines. At a QW width close to the critical one the presence of band inversion and the emergence of a gapless band structure, similar to bilayer graphene, are shown for a structure with a single QW. The shift of magnetoabsorption lines as the carrier concentration changes due to the persistent photoconductivity effect associated with a change in the potential profile because of trap charge exchange is detected. This opens up the possibility for controlling topological phase transitions in such structures.

Estimating cumulative soil accumulation rates with in situ-produced cosmogenic nuclide depth profiles

International Nuclear Information System (INIS)

Phillips, William M.

2000-01-01

A numerical model relating spatially averaged rates of cumulative soil accumulation and hillslope erosion to cosmogenic nuclide distribution in depth profiles is presented. Model predictions are compared with cosmogenic 21 Ne and AMS radiocarbon data from soils of the Pajarito Plateau, New Mexico. Rates of soil accumulation and hillslope erosion estimated by cosmogenic 21 Ne are significantly lower than rates indicated by radiocarbon and regional soil-geomorphic studies. The low apparent cosmogenic erosion rates are artifacts of high nuclide inheritance in cumulative soil parent material produced from erosion of old soils on hillslopes. In addition, 21 Ne profiles produced under conditions of rapid accumulation (>0.1 cm/a) are difficult to distinguish from bioturbated soil profiles. Modeling indicates that while 10 Be profiles will share this problem, both bioturbation and anomalous inheritance can be identified with measurement of in situ-produced 14 C

Evaluation of the contamination for Hg and Pb in horticultural soils of the Bogota Savanna and of the effect of the Hg and Pb of the watering water and of the soils in several vegetables

International Nuclear Information System (INIS)

Vargas Zarate, Orlando; Mejia C, Leonidas

1998-01-01

Soils of six different horticultural zones of the Sabanna of Bogota were studied to quantify Hg and Pb accumulation in soils and crops caused by traditional and continuous irrigation with the highly polluted waters of Bogota River and its effluents. Soils of site No.6 representative of Rio Bogota is series (a fine clayed, mixed, isothermic family of aeric fluventic tropaquepts) was selected for greenhouse experiments conducted to show: a) The amounts of Hg and Pb absorbed by 3 different vegetables (lettuce, cucumber and carrots) grown under greenhouse conditions, irrigated with waters with variable Hg and Pb concentrations; b) the effects of increased levels of Hg and Pb in irrigation water on the accumulation level of both metals in soils at the harvest; and c) the individual effect and interactions of Hg and Pb on yields of each one vegetable. Results afforded this conclusions: 1) soils of all six sites have average Hg and Pb concentrations (0.5 and 110 ppm respectively) which exceed normal levels for soils (who, 1976); site 6 has the highest level of Hg and Pb accumulation (1.6 and 3.36 ppm); 2) for all three vegetables Hg and Pb accumulation level was almost proportional to Hg and Pb concentration in irrigation water; 3) Hg and Pb concentration in edible parts was different for each vegetable. Average contents of Hg and Pb were respectively 33 ppb and 172 ppm in lettuce; 24 ppb and 10 ppm in cucumber and 36 ppb and 48 ppm in carrots. Average absorption of Pb in lettuce was 17 times higher than in cucumber and 3.5 times higher than in carrots; Pb absorption levels widely surpass those recommended as permissible by WHO (1976) 4) high correlation coefficients were found between Hg and Pb absorption by lettuce (R=0.94 and 0.97 respectively), cucumber (R=0.89 and R=0.80 respectively) and carrots (R=0.99 y R=0.85 respectively) and the corresponding Hg and Pb accumulation levels in soils at harvest; 5) Effects of Hg and Pb levels in irrigation water on yields was

Ruditapes philippinarum and Ruditapes decussatus under Hg environmental contamination.

Science.gov (United States)

Velez, Cátia; Galvão, Petrus; Longo, Renan; Malm, Olaf; Soares, Amadeu M V M; Figueira, Etelvina; Freitas, Rosa

2015-08-01

The native species Ruditapes decussatus and the invasive species Ruditapes philippinarum have an important ecological role and socio-economic value, from the Atlantic and Mediterranean to the Indo-Pacific region. In the aquatic environment, they are subjected to the presence of different contaminants, such as mercury (Hg) and its methylated form, methylmercury (MeHg). However, few studies have assessed the impacts of Hg on bivalves under environmental conditions, and little is known on bivalve oxidative stress patterns due to Hg contamination. Therefore, this study aims to assess the Hg contamination in sediments as well as the concentration of Hg and MeHg in R. decussatus and R. philippinarum, and to identify the detoxification strategies of both species living in sympatry, in an aquatic system with historical Hg contamination. The risk to human health due to the consumption of clams was also evaluated. The results obtained demonstrated that total Hg concentration found in sediments from the most contaminated area was higher than the maximum levels established by Sediment Quality Guidelines. This study further revealed that the total Hg and MeHg accumulation in both species was strongly correlated with the total Hg contamination of the sediments. Nonetheless, the THg concentration in both species was lower than maximum permissible limits (MPLs) of THg defined by international organizations. R. decussatus and R. philippinarum showed an increase in lipid peroxidation levels along with the increase of THg accumulation by clams. Nevertheless, for both species, no clear trend was obtained regarding the activity of antioxidant (superoxide dismutase, catalase) and biotransformation (glutathione S-transferase) enzymes and metallothioneins with the increase of THg in clams. Overall, the present work demonstrated that both species can be used as sentinel species of contamination and that the consumption of these clams does not constitute a risk for human health.

Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

Science.gov (United States)

Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

2015-01-01

Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

Wading bird guano contributes to Hg accumulation in tree island soils in the Florida Everglades

International Nuclear Information System (INIS)

Zhu, Yingjia; Gu, Binhe; Irick, Daniel L.; Ewe, Sharon; Li, Yuncong; Ross, Michael S.; Ma, Lena Q.

2014-01-01

Tree islands are habitat for wading birds and a characteristic landscape feature in the Everglades. A total of 93 surface soil and 3 soil core samples were collected from 7 degraded/ghost and 34 live tree islands. The mean Hg concentration in surface soils of ghost tree islands was low and similar to marsh soil. For live tree islands, Hg concentrations in the surface head region were considerably greater than those in mid and tail region, and marsh soils. Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings (105 μg kg −1 ) and plant leaves (53 μg kg −1 ). In addition, Hg concentrations and δ 15 N values displayed positive correlation in soils influenced by guano. During 1998–2010, estimated annual Hg deposition by guano was 148 μg m −2 yr −1 and ∼8 times the atmospheric deposition. Highlights: • Hg concentrations in the head region of tree islands were the highest. • Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings and plant leaves. • Hg concentrations and δ 15 N values showed positive correlation in soils influenced by guano. • Estimated annual Hg deposition by guano was 148 μg m −2 yr −1 , ∼8 times the atmospheric deposition. -- The annual Hg deposition by bird guano to tree island soils in the Everglades was ∼8 times the atmospheric deposition

Accumulation of total mercury and methylmercury in rice plants collected from different mining areas in China

International Nuclear Information System (INIS)

Meng, Mei; Li, Bing; Shao, Jun-juan; Wang, Thanh; He, Bin; Shi, Jian-bo; Ye, Zhi-hong; Jiang, Gui-bin

2014-01-01

A total of 155 rice plants were collected from ten mining areas in three provinces of China (Hunan, Guizhou and Guangdong), where most of mercury (Hg) mining takes place in China. During the harvest season, whole rice plants were sampled and divided into root, stalk and leaf, husk and seed (brown rice), together with soil from root zone. Although the degree of Hg contamination varied significantly among different mining areas, rice seed showed the highest ability for methylmercury (MeHg) accumulation. Both concentrations of total mercury (THg) and MeHg in rice plants were significantly correlated with Hg levels in soil, indicating soil is still an important source for both inorganic mercury (IHg) and MeHg in rice plants. The obvious discrepancy between the distribution patterns of THg and MeHg reflected different pathways of IHg and MeHg accumulation. Water soluble Hg may play more important role in MeHg accumulation in rice plants. -- Highlights: • Distribution patterns indicated different pathways of IHg and MeHg accumulation. • Soil is an important source for both THg and MeHg to rice plants. • Water soluble Hg may play more important role in MeHg accumulation in rice plants. -- The distribution patterns indicate different pathways of IHg and MeHg accumulation in rice plants

Maternal-fetal distribution of mercury (203Hg) released from dental amalgam fillings

International Nuclear Information System (INIS)

Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L.

1990-01-01

In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered

Accumulation of mercury and methylmercury by mushrooms and earthworms from forest soils

International Nuclear Information System (INIS)

Rieder, Stephan R.; Brunner, Ivano; Horvat, Milena; Jacobs, Anna; Frey, Beat

2011-01-01

Accumulation of total and methyl-Hg by mushrooms and earthworms was studied in thirty-four natural forest soils strongly varying in soil physico-chemical characteristics. Tissue Hg concentrations of both receptors did hardly correlate with Hg concentrations in soil. Both total and methyl-Hg concentrations in tissues were species-specific and dependent on the ecological groups of receptor. Methyl-Hg was low accounting for less than 5 and 8% of total Hg in tissues of mushrooms and earthworms, respectively, but with four times higher concentrations in earthworms than mushrooms. Total Hg concentrations in mushrooms averaged 0.96 mg Hg kg -1 dw whereas litter decomposing mushrooms showed highest total Hg and methyl-Hg concentrations. Earthworms contained similar Hg concentrations (1.04 mg Hg kg -1 dw) whereas endogeic earthworms accumulated highest amounts of Hg and methyl-Hg. - Highlights: → Hg and MeHg concentrations in mushrooms and earthworms at unpolluted forest soils. → Mushrooms and earthworms contained similar Hg concentrations. → MeHg was present in traces but four times higher in earthworms than in mushrooms. → Ecophysiological group influenced Hg and MeHg concentration in both receptors. - Accumulation of Hg and methyl-Hg by mushrooms and earthworms is species- and ecophysiological group dependent.

Accumulation of mercury and methylmercury by mushrooms and earthworms from forest soils

Energy Technology Data Exchange (ETDEWEB)

Rieder, Stephan R. [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Institute for Biogeochemistry and Pollutant Dynamics, ETH Zuerich, 8092 Zuerich (Switzerland); Brunner, Ivano [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Horvat, Milena [Jozef Stefan Institute, 1001 Ljubliana (Slovenia); Jacobs, Anna [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Department of Environmental Chemistry, University of Kassel, 37213 Witzenhausen (Germany); Frey, Beat, E-mail: beat.frey@wsl.ch [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland)

2011-10-15

Accumulation of total and methyl-Hg by mushrooms and earthworms was studied in thirty-four natural forest soils strongly varying in soil physico-chemical characteristics. Tissue Hg concentrations of both receptors did hardly correlate with Hg concentrations in soil. Both total and methyl-Hg concentrations in tissues were species-specific and dependent on the ecological groups of receptor. Methyl-Hg was low accounting for less than 5 and 8% of total Hg in tissues of mushrooms and earthworms, respectively, but with four times higher concentrations in earthworms than mushrooms. Total Hg concentrations in mushrooms averaged 0.96 mg Hg kg{sup -1} dw whereas litter decomposing mushrooms showed highest total Hg and methyl-Hg concentrations. Earthworms contained similar Hg concentrations (1.04 mg Hg kg{sup -1} dw) whereas endogeic earthworms accumulated highest amounts of Hg and methyl-Hg. - Highlights: > Hg and MeHg concentrations in mushrooms and earthworms at unpolluted forest soils. > Mushrooms and earthworms contained similar Hg concentrations. > MeHg was present in traces but four times higher in earthworms than in mushrooms. > Ecophysiological group influenced Hg and MeHg concentration in both receptors. - Accumulation of Hg and methyl-Hg by mushrooms and earthworms is species- and ecophysiological group dependent.

Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania).

Science.gov (United States)

Bravo, Andrea G; Loizeau, Jean-Luc; Dranguet, Perrine; Makri, Stamatina; Björn, Erik; Ungureanu, Viorel Gh; Slaveykova, Vera I; Cosio, Claudia

2016-06-01

Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

Accumulation, subcellular distribution and toxicity of inorganic mercury and methylmercury in marine phytoplankton

Energy Technology Data Exchange (ETDEWEB)

Wu Yun [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong); Wang Wenxiong, E-mail: wwang@ust.hk [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong)

2011-10-15

We examined the accumulation, subcellular distribution, and toxicity of Hg(II) and MeHg in three marine phytoplankton (the diatom Thalassiosira pseudonana, the green alga Chlorella autotrophica, and the flagellate Isochrysis galbana). For MeHg, the inter-species toxic difference could be best interpreted by the total cellular or intracellular accumulation. For Hg(II), both I. galbana and T. pseudonana exhibited similar sensitivity, but they each accumulated a different level of Hg(II). A higher percentage of Hg(II) was bound to the cellular debris fraction in T. pseudonana than in I. galbana, implying that the cellular debris may play an important role in Hg(II) detoxification. Furthermore, heat-stable proteins were a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). Elucidating the different subcellular fates of Hg(II) and MeHg may help us understand their toxicity in marine phytoplankton at the bottom of aquatic food chains. - Highlights: > The inter-species toxic difference of methylmercury in marine phytoplankton can be explained by its total cellular or intracellular accumulation. > The inter-species toxic difference of inorganic mercury in marine phytoplankton can be explained by its subcellular distribution. > Heat-stable protein was a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). - The inter-species difference in methylmercury and inorganic mercury toxicity in phytoplankton can be explained by cellular accumulation and subcellular distribution.

Accumulation, subcellular distribution and toxicity of inorganic mercury and methylmercury in marine phytoplankton

International Nuclear Information System (INIS)

Wu Yun; Wang Wenxiong

2011-01-01

We examined the accumulation, subcellular distribution, and toxicity of Hg(II) and MeHg in three marine phytoplankton (the diatom Thalassiosira pseudonana, the green alga Chlorella autotrophica, and the flagellate Isochrysis galbana). For MeHg, the inter-species toxic difference could be best interpreted by the total cellular or intracellular accumulation. For Hg(II), both I. galbana and T. pseudonana exhibited similar sensitivity, but they each accumulated a different level of Hg(II). A higher percentage of Hg(II) was bound to the cellular debris fraction in T. pseudonana than in I. galbana, implying that the cellular debris may play an important role in Hg(II) detoxification. Furthermore, heat-stable proteins were a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). Elucidating the different subcellular fates of Hg(II) and MeHg may help us understand their toxicity in marine phytoplankton at the bottom of aquatic food chains. - Highlights: → The inter-species toxic difference of methylmercury in marine phytoplankton can be explained by its total cellular or intracellular accumulation. → The inter-species toxic difference of inorganic mercury in marine phytoplankton can be explained by its subcellular distribution. → Heat-stable protein was a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). - The inter-species difference in methylmercury and inorganic mercury toxicity in phytoplankton can be explained by cellular accumulation and subcellular distribution.

Maternal-fetal distribution of mercury ( sup 203 Hg) released from dental amalgam fillings

Energy Technology Data Exchange (ETDEWEB)

Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L. (Univ. of Calgary, Alberta (Canada))

1990-04-01

In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.

A test of the stability of Cd, Cu, Hg, Pb and Zn profiles over two decades in lake sediments near the Flin Flon Smelter, Manitoba, Canada

Energy Technology Data Exchange (ETDEWEB)

Percival, J.B.; Outridge, P.M., E-mail: outridge@nrcan.gc.ca

2013-06-01

Lake sediments are valuable archives of atmospheric metal deposition, but the stability of some element profiles may possibly be affected by diagenetic changes over time. In this extensive case study, the stability of sedimentary Cd, Cu, Hg, Pb and Zn profiles was assessed in dated sediment cores that were collected in 2004 from four smelter-affected lakes near Flin Flon, Manitoba, which had previously been cored in 1985. Metal profiles determined in 1985 were in most cases clearly reproduced in the corresponding sediment layers in 2004, although small-scale spatial heterogeneity in metal distribution complicated the temporal comparisons. Pre-smelter (i.e. pre-1930) increases in metal profiles were likely the result of long-range atmospheric metal pollution, coupled with particle mixing at the 1930s sediment surface. However, the close agreement between key inflection points in the metal profiles sampled two decades apart suggests that metals in most of the lakes, and Hg and Zn in the most contaminated lake (Meridian), were stable once the sediments were buried below the surface mixed layer. Cadmium, Cu and Pb profiles in Meridian Lake did not agree as well between studies, showing evidence of upward remobilization over time. Profiles of redox-indicator elements (Fe, Mn, Mo and U) suggested that the rate of Mn oxyhydroxide recycling within sediment was more rapid in Meridian Lake, which may have caused the Cd, Cu and Pb redistribution. - Highlights: • Sedimentary Cd, Cu, Hg, Pb and Zn profiles in four lakes were mostly unchanged over 19 years. • In one lake, Cd, Cu and Pb profiles were offset relative to the originals. • The offset could indicate diagenetic upcore dispersal of these metals.

Heavy metal accumulation potential and medicinal property of Bacopa monnieri - a paradox

Directory of Open Access Journals (Sweden)

Nabeesa Salim

2011-12-01

Full Text Available Bioaccumulation of Mercury and Cadmium in Bacopa monnieri (L. Pennell, cultivated in Hoagland medium artificially contaminated with micro quantities of HgCl2 and CdCl2 is investigated. Bioaccumulation potential of B. monnieri is more towards Cd than Hg. Absorption and translocation of Hg and Cd are proportional to the availability of the metal in the growth media and period of growth. Effect of acidic pH showed enhanced accumulation while basic pH resulted in significant reduction in the accumulation of Hg and exorbitant reduction of Cd. As a result of combined treatment of HgCl2 and CdCl2, accumulation was very low in both acidic and basic pH. In addition to pH, antagonistic effect of Ca2+ present in lime water which was added to raise the pH of the growth medium also controls the accumulation and absorption of Hg and Cd ions. Bioaccumulation of Hg and Cd in B. monnieri reveals the phytoremediation potential while the bioaccumulation is hazards to health since the plant is highly medicinal and one important ingredient of many Ayurvedic preparations.

One century sedimentary record of Hg and Pb pollution in the Sagua estuary (Cuba) derived from 210Pb and 137Cs chronology

International Nuclear Information System (INIS)

Diaz-Asencio, M.; Alonso-Hernandez, C.M.; Bolanos-Alvarez, Y.; Gomez-Batista, M.; Pinto, V.; Morabito, R.; Hernandez-Albernas, J.I.; Eriksson, M.; Sanchez-Cabeza, J.A.

2009-01-01

The vertical distribution of Hg and Pb were determined in a sediment core collected from the Sagua estuary (North Cuba) that receives input from the Sagua river, one of the most polluted rivers discharging into the Cuban coastal environment. Depth profiles of metal concentrations were converted to time-based profiles using the 210 Pb dating method and confirmed with the 137 Cs fallout peak. The mean mass accumulation rate was estimated to be 0.17 ± 0.04 g cm -2 y -1 (mean sediment accumulation rate 0.52 ± 0.13 cm y -1 ) and the core bottom was estimated to date back about 130 years. The historical sedimentary record showed a strong enrichment of mercury concentrations in the past decades, caused by the incomplete treatment of industrial wastes from a chlor-alkali plant with mercury-cell technology in the Sagua river basin. Lead fluxes to sediments showed a gradual increase from the 1920s to present, which agrees with a population increase in Sagua la Grande City. Fluxes of both metals have increased the past 25 years, with values reaching a maximum of 0.5 and 3.9 μg cm -2 y -1 for Hg and Pb, respectively.

Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor

Science.gov (United States)

Amado Filho, G. M.; Andrade, L. R.; Farina, M.; Malm, O.

The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702±318 μg Hg g -1 was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding.

Accumulation, transfer, and environmental risk of soil mercury in a rapidly industrializing region of the Yangtze River Delta, China

Energy Technology Data Exchange (ETDEWEB)

Huang, Biao; Yan, Lianxiang; Sun, Weixia; Zhao, Yongcun; Shi, Xuezheng [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Wang, Mei [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Graduate Univ. of the Chinese Academy of Sciences, Beijing (China); Weindorf, David C. [Louisiana State Univ., Baton Rouge, LA (United States). AgCenter

2011-06-15

Purpose: Mercury (Hg) accumulation and transfer in soil ecosystems has been altered on local, regional, and even global scales, and their environmental risk has increasingly been a concern to the public and the scientific community. Materials and methods: A county level region in Zhangjiagang County, the Yangtze River Delta (YRD) region of China and a factory with Hg-contaminated wastewater discharging within the region were selected to study the accumulation, bioavailability, and transfer of Hg from different sources in soils and crops under rapid industrialization, urbanization, and intensive agricultural activities. Regional soil samples close to and away from factories and local soil and crop samples around a typical factory were collected in the YRD region of China. Soil and crop Hg and basic soil properties were examined. Results and discussion: Significant soil Hg accumulation was found in soils away from factories regardless of Cambosols (Entisols) and Anthrosols (Inceptisols), while the mobile HCl-extractable Hg (HCl-Hg) were greater in soils closer to factories due to a decrease and increase in soil pH and organic matter. A high level of soil total Hg (T-Hg) was found around the factory, and soil and crop Hg accumulation in the vicinity of the factory was localized with an exponential decrease as distance away from the wastewater discharge outlet increased. Although Hg accumulated in these soils, the T-Hg levels at only a few sampling sites in acidic Anthrosols area were found to exceed the second most stringent critical value of Chinese Environmental Quality Standards for Soils. Conclusions: Considering the cessation of Hg-containing agrochemicals and limitation of effects of industrial activities on Hg accumulation, more attention should be paid to the changes in soil properties and crop rotations than controlling the pathways of Hg entering soils because the current environmental risk is mobilization of accumulated soil Hg. (orig.)

Speciation of Hg in lichens

International Nuclear Information System (INIS)

Jereb, Vesna; Horvat, Milena

2002-01-01

Lichens have long been regarded as a suitable tool for monitoring the relative levels of atmospheric pollutants. Lichens have neither roots, a waxy cuticle nor stomata: hence, for mineral nutrition they are largely dependent on wet and dry deposition from the atmosphere. Moreover, lichens are perennial and can accumulate elements over long periods of time. Therefore, concentrations of elements in lichens represent the average levels of elements in the atmosphere for a long period of time. The epiphytic lichen Hypogymnia physodes is a good bioindicator of air pollution with total mercury (THg). In addition, it contains small amounts of methylmercury (MeHg + ). The first aim of our work was to test analytical techniques for determination of MeHg in lichens taken from different locations in Idrija and reference locations

Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor

Energy Technology Data Exchange (ETDEWEB)

Filho, G.M.A. [Instituto de Pesquisas Jardim Botanico do Rio de Janeiro (Brazil). Programa Zona Costeira; Andrade, L.R.; Farina, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Ciencias Biomedicas, Departamento de Anatomia; Malm, O. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Biofisica Carlos Chagas Filho, Laboratorio de Radioisotopos Eduardo Penna Franca

2002-07-01

The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702{+-}318{mu}g Hgg{sup -1} was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding. (author)

In situ bioavailability of DDT and Hg in sediments of the Toce River (Lake Maggiore basin, Northern Italy): accumulation in benthic invertebrates and passive samplers.

Science.gov (United States)

Pisanello, Francesca; Marziali, Laura; Rosignoli, Federica; Poma, Giulia; Roscioli, Claudio; Pozzoni, Fiorenzo; Guzzella, Licia

2016-06-01

DDT and mercury (Hg) contamination in the Toce River (Northern Italy) was caused by a factory producing technical DDT and using a mercury-cell chlor-alkali plant. In this study, DDT and Hg contamination and bioavailability were assessed by using different approaches: (1) direct evaluation of sediment contamination, (2) assessment of bioaccumulation in native benthic invertebrates belonging to different taxonomic/functional groups, and (3) evaluation of the in situ bioavailability of DDT and Hg using passive samplers. Sampling sites were selected upstream and downstream the industrial plant along the river axis. Benthic invertebrates (Gammaridae, Heptageniidae, and Diptera) and sediments were collected in three seasons and analyzed for DDT and Hg content and the results were used to calculate the biota sediment accumulation factor (BSAF). Polyethylene passive samplers (PEs) for DDT and diffusive gradients in thin films (DGTs) for Hg were deployed in sediments to estimate the concentration of the toxicants in pore water. Analysis for (DDx) were performed using GC-MS. Accuracy was within ±30 % of the certified values and precision was >20 % relative standard deviation (RSD). Total mercury concentrations were determined using an automated Hg mercury analyzer. Precision was >5 % and accuracy was within ±10 % of certified values. The results of all the approaches (analysis of sediment, biota, and passive samplers) showed an increasing contamination from upstream to downstream sites. BSAF values revealed the bioavailability of both contaminants in the study sites, with values up to 49 for DDx and up to 3.1 for Hg. No correlation was found between values in sediments and the organisms. Concentrations calculated using passive samplers were correlated with values in benthic invertebrates, while no correlation was found with concentrations in sediments. Thus, direct analysis of toxicant in sediments does not provide a measurement of bioavailability. On the contrary

HgSe(Te)-HgHal2 systems

International Nuclear Information System (INIS)

Pan'ko, V.V.; Khudolij, V.A.; Voroshilov, Yu.V.

1989-01-01

Using the methods of differential thermal and X-ray phase analyses the character of chemical interaction in the systems HgTe(Se)-HgHal 2 , where Hal is Cl, Br, I, is investigated. Formation of compounds Hg 3 Se 2 Hal 2 , Hg 3 Te 2 Hal 2 , Hg 3 TeCl 4 and Hg 3 TeBr 4 in these systems is established. The phase diagrams of the studied systems are presented. The parameters of elementary cells of the compounds with the unknown structure, as well as their unknown physicochemical properties, are determined

Accumulation of Arsenic and Mercury in Different Bio-bed Padding Materials

Directory of Open Access Journals (Sweden)

LIU Tian-yu

2016-07-01

Full Text Available In order to study the accumulation and distribution of As, Hg in different bio-bed padding materials while implementing bio-bed raising method, three kinds of bio-bed padding materials were well designed, which consisted of sawdust(S, sawdust + rice husk(SR and sawdust + rice husk + straw(SRS. For a year and a half, the contents of As, Hg at different depth were measured when four groups of fattening pig breeding had finished to analyze the accumulation and distribution of As, Hg in different bio-bed padding materials, which could provide a theoretical basis for follow-up application of bio-bed padding materials in agriculture. The results showed that, the accumulation of As and Hg, at different levels, occurred during four pig-raising cycles. When 4 groups of fattening pig breeding finished, the largest accumulation of As and Hg occurred in SRS bio-beds, respectively reached 1921.7 mg per sty and 21.1 mg per sty. The As and Hg contents of S, SR,SRS were 2.921, 2.190, 2.621 mg·kg-1 and 0.048, 0.036, 0.042 mg·kg-1, respectively, which met the China's Organic Fertilizer Agriculture Standards(NY 525-2012, and Farmland Environmental Quality Evaluation Standards For Edible Agricultural Products(HJ/T 332-2006.

Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies

International Nuclear Information System (INIS)

Parsons, Matthew J.; Long, David T.; Yohn, Sharon S.

2010-01-01

Research highlights: → Identifying the cause of Hg contamination via correlations to iron ore production. → Using Hg:Al ratio to show changes in pathway from a point to non-point source. → Overcoming challenges to age determination using event-based dating. → Using sediment cores to estimate recovery rates and identify arrested recovery. - Abstract: Deer Lake is an impoundment located near Ishpeming, Michigan, USA. Iron mining assay laboratories located in Ishpeming disposed of Hg salts to the city sewer whose outfall was located along an inlet to Deer Lake. An effort to remediate the system in the mid 1980s which consisted of drawing down water in the impoundment in order to volatize Hg from the sediments did not result in recovery of the system. Since the mid 1990s, the remediation strategy has been to allow the continual burial of the contaminated sediments, i.e., natural recovery. The goal of this study was to assess the effectiveness of this strategy. This was accomplished by investigating State of the system in terms of its recovery and estimating the time frame for recovery. Sediment cores were collected in 2000 to determine historical trends in accumulation rates and concentrations of Hg and other metals. Sedimentation rates and sediment ages were estimated using 210 Pb. Event-based dating (e.g., peak of 137 Cs in 1963) was used to supplement 210 Pb data due to non-monotonic features in the 210 Pb profile and activities that were not at supported levels at the base of the core. Selected results are that: (1) drawdown significantly influenced sedimentation patterns causing slopes for 210 Pb profiles that reflected the influx of older sediment, (2) periods of Fe production correlate to Hg loading indicating the point source for contamination, a relationship not previously identified, (3) Hg:Al ratios indicate a recent change to a watershed pathway for Hg loading and (4) Hg concentrations had decreased from their peak, remain elevated, and were

Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies

Energy Technology Data Exchange (ETDEWEB)

Parsons, Matthew J. [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Long, David T., E-mail: long@msu.edu [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Yohn, Sharon S. [Juniata College, Raystown Field Station, Brumbaugh Academic Center, Huntingdon, PA 16652 (United States)

2010-11-15

Research highlights: {yields} Identifying the cause of Hg contamination via correlations to iron ore production. {yields} Using Hg:Al ratio to show changes in pathway from a point to non-point source. {yields} Overcoming challenges to age determination using event-based dating. {yields} Using sediment cores to estimate recovery rates and identify arrested recovery. - Abstract: Deer Lake is an impoundment located near Ishpeming, Michigan, USA. Iron mining assay laboratories located in Ishpeming disposed of Hg salts to the city sewer whose outfall was located along an inlet to Deer Lake. An effort to remediate the system in the mid 1980s which consisted of drawing down water in the impoundment in order to volatize Hg from the sediments did not result in recovery of the system. Since the mid 1990s, the remediation strategy has been to allow the continual burial of the contaminated sediments, i.e., natural recovery. The goal of this study was to assess the effectiveness of this strategy. This was accomplished by investigating State of the system in terms of its recovery and estimating the time frame for recovery. Sediment cores were collected in 2000 to determine historical trends in accumulation rates and concentrations of Hg and other metals. Sedimentation rates and sediment ages were estimated using {sup 210}Pb. Event-based dating (e.g., peak of {sup 137}Cs in 1963) was used to supplement {sup 210}Pb data due to non-monotonic features in the {sup 210}Pb profile and activities that were not at supported levels at the base of the core. Selected results are that: (1) drawdown significantly influenced sedimentation patterns causing slopes for {sup 210}Pb profiles that reflected the influx of older sediment, (2) periods of Fe production correlate to Hg loading indicating the point source for contamination, a relationship not previously identified, (3) Hg:Al ratios indicate a recent change to a watershed pathway for Hg loading and (4) Hg concentrations had decreased from

Study of the odd mass transition nuclei: 185Hg, 187Hg, 189Hg and 183Ir

International Nuclear Information System (INIS)

Zerrouki, A.

1979-01-01

The radioactive decay of 185 Tl, 186 Tl, 187 Tl has been studied on the isotope separator Isocele II working on line with the Orsay synchrocyclotron from Au( 3 He,xn) reactions: the emitted α lines have been measured and the main γ lines belonging to the 187 Tl→ 187 Hg decay have been identified. The 185 Hg, 187 Hg, 189 Hg high spin states have been studied using the following (HI,xn) reactions obtained on the Strasbourg MP Tandem: 168 Er( 24 Mg,xn) 187 Hg, 188 Hg, 166 Er( 24 Mg,xn) 185 Hg, 186 Hg, 157 Gd( 32 S,xn) 184 Hg, 185 Hg, 158 Gd( 32 S,5n) 185 Hg and 175 Lu( 19 F,5n) 189 Hg. The excitation functions are indicated and a high spin level scheme of 189 Hg is proposed: it is compared to the 'quasiparticle + triaxial rotor' model predictions. A level scheme of 183 Ir is proposed from the data collected at Isolde II (CERN) by Dr. SCHUCK: it is analysed within the framework of the same theoretical model used above [fr

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands.

Science.gov (United States)

Morrison, R John; Peshut, Peter J; West, Ronald J; Lasorsa, Brenda K

2015-07-15

We investigated Hg in muscle tissue of fish species from three trophic levels on fringing reefs of Tutuila (14°S, 171°W), plus water, sediment and turf alga. Accumulation of total Hg in the herbivore Acanthurus lineatus (Acanthuridae, lined surgeonfish, (n=40)) was negligible at 1.05 (±0.04) ng g(-1) wet-weight, (∼65% occurring as methyl Hg). The mid-level carnivore Parupeneus spp. (Mullidae, goatfishes (n=10)) had total Hg 29.8 (±4.5) ng g(-1) wet-weight (∼99% as methyl Hg). Neither A. lineatus or Parupeneus spp. showed a propensity to accumulate Hg based on body size. Both groups were assigned a status of "un-restricted" for monthly consumption limits for non-carcinogenic health endpoints for methyl Hg. The top-level carnivore Sphyraena qenie (Sphyraenidae, blackfin barracuda, n=3) had muscle tissue residues of 105, 650 and 741 ng g(-1) wet-weight (100% methyl Hg, with increasing concentration with body mass, suggesting that S. qenie >15 kg would have a recommendation of "no consumption". Copyright © 2015 Elsevier Ltd. All rights reserved.

Does pre-exposure to warming conditions increase Mytilus galloprovincialis tolerance to Hg contamination?

Science.gov (United States)

Freitas, Rosa; Coppola, Francesca; Henriques, Bruno; Wrona, Fredrick; Figueira, Etelvina; Pereira, Eduarda; Soares, Amadeu M V M

2017-12-01

The degree to which marine invertebrate populations can tolerate extreme weather events, such as short-term exposure to high temperatures, and the underlying biochemical response mechanisms are not yet fully understood. Furthermore, scarce information is available on how marine organisms respond to the presence of pollutants after exposure to heat stress conditions. Therefore, the present study aimed to understand how the mussel Mytilus galloprovincialis responds to Hg pollution after pre-exposure to warming conditions. Mussels were exposed to control (17°C) and warming (21°C) conditions during 14days, followed by Hg contamination during 28days under different temperature regimes (17 and 21°C). The results obtained demonstrated significantly higher Hg concentrations in mussels under 17°C during the entire experiment than in organisms exposed to 21°C during the same period, which resulted in higher oxidative stress in mussels under control temperature. Significantly higher Hg concentrations were also observed in mussels pre-exposed to 21°C followed by a 17°C exposure comparing with organisms maintained the entire experiment at 21°C. These results may be explained by higher metabolic capacity in organisms exposed to 17°C after pre-exposure to 21°C that although induced antioxidant defences were not enough to prevent oxidative stress. No significant differences in terms of Hg concentration were found between mussels exposed to 17°C during the entire experiment and organisms pre-exposed to 21°C followed by a 17°C exposure, leading to similar oxidative stress levels in mussels exposed to both conditions. Therefore, our findings demonstrated that pre-exposure to warming conditions did not change mussels' accumulation and tolerance to Hg in comparison to Hg contaminated mussels maintained at control temperature. Furthermore, the present study indicate that organisms maintained under warming conditions for long periods may prevent the accumulation of

History of atmospheric deposition of Cd, Hg, and Pb in North America: Evidence from lake and peat bog sediments

International Nuclear Information System (INIS)

Norton, S.A.; Dillon, P.J.; Evans, R.D.; Mierle, G.; Kahl, J.S.

1990-01-01

The precipitation chemistry and lake and peat sediment chemistry of three metals emitted to the atmosphere in significant amounts as a result of anthropogenic activity are reviewed. The three metals, Cd, Hg, and Pb, have contrasting source terms, atmospheric residence times, and chemical mobility. Lake and ombrotrophic peat bog sediments record increases in the concentrations and accumulation rates of the metals for most of temperate North America for the last 100 years. These increases are largely related to the burning of coal, smelting of nonferrous metals, the transportation industry, and the industrial production of chlorine. Modern atmospheric fluxes of Cd in central North America are about 1,000 times background fluxes; accumulation rates for Cd in sediments have increased two to 3 times above background, beginning about 100 years ago. Global scale Hg pollution off the atmosphere is suggested by concentrations in northern hemisphere air that are double the Hg content of southern hemisphere air. Accumulation rates of Hg in sediment have approximately doubled in the last 100 years. However, these rates are approximately an order of magnitude less than those for Cd. Modern increases in Pb concentrations are ubiquitous for all lakes examines thus far in North America. Input is from multiple sources and thus the timing of increased accumulation rates in sediment varies across the continent. Typical modern accumulation rates reach maxima at 20 to 30 mg/sq-m/yr, or 100 times that of Cd and 1,000 times that off Hg. Recent decreases in atmospheric lead are reflected in decreases in the accumulation rate of Pb in both lake and peat bog sediment in eastern North America

Prediction of methylmercury accumulation in rice grains by chemical extraction methods

International Nuclear Information System (INIS)

Zhu, Dai-Wen; Zhong, Huan; Zeng, Qi-Long; Yin, Ying

2015-01-01

To explore the possibility of using chemical extraction methods to predict phytoavailability/bioaccumulation of soil-bound MeHg, MeHg extractions by three widely-used extractants (CaCl 2 , DTPA, and (NH 4 ) 2 S 2 O 3 ) were compared with MeHg accumulation in rice grains. Despite of variations in characteristics of different soils, MeHg extracted by (NH 4 ) 2 S 2 O 3 (highly affinitive to MeHg) correlated well with grain MeHg levels. Thus (NH 4 ) 2 S 2 O 3 extraction, solubilizing not only weakly-bound and but also strongly-bound MeHg, may provide a measure of ‘phytoavailable MeHg pool’ for rice plants. Besides, a better prediction of grain MeHg levels was obtained when growing condition of rice plants was also considered. However, MeHg extracted by CaCl 2 or DTPA, possibly quantifying ‘exchangeable MeHg pool’ or ‘weakly-complexed MeHg pool’ in soils, may not indicate phytoavailable MeHg or predict grain MeHg levels. Our results provided the possibility of predicting MeHg phytoavailability/bioaccumulation by (NH 4 ) 2 S 2 O 3 extraction, which could be useful in screening soils for rice cultivation in contaminated areas. - Highlights: • MeHg extraction by (NH 4 ) 2 S 2 O 3 correlates well with its accumulation in rice grains. • MeHg extraction by (NH 4 ) 2 S 2 O 3 provides a measure of phytoavailable MeHg in soils. • Some strongly-bound MeHg could be desorbed from soils and available to rice plants. • MeHg extraction by CaCl 2 or DTPA could not predict grain MeHg levels. - Methylmercury extraction from soils by (NH 4 ) 2 S 2 O 3 could possibly be used for predicting methylmercury phytoavailability and its bioaccumulation in rice grains

Accumulation of Heavy Metals in Crayfish and Fish from Selected Czech Reservoirs

Directory of Open Access Journals (Sweden)

Iryna Kuklina

2014-01-01

Full Text Available To evaluate the accumulation of aluminium, cadmium, chromium, copper, lead, mercury, nickel, and zinc in crayfish and fish organ tissues, specimens from three drinking water reservoirs (Boskovice, Landštejn, and Nová Říše and one contaminated site (Darkovské moře in the Czech Republic were examined. Crayfish hepatopancreas was confirmed to be the primary accumulating site for the majority of metals (Cu > Zn > Ni > Cd > Cr, while Hg and Cr were concentrated in abdominal muscle, and Al and Pb were concentrated in gill. Metals found in Nová Říše specimens included Cu > Zn > Ni and those found in Boskovice included Zn > Hg > Cr. Cd concentrations were observed only in Landštejn specimens, while contaminated Darkovské moře specimens showed the highest levels of accumulation (Cu > Al > Zn > Pb. The majority of evaluated metals were found in higher concentrations in crayfish: Cu > Al > Zn > Ni > Cr > Cd > Pb, with Hg being the only metal accumulating higher in fish. Due to accumulation similarities of Al in crayfish and fish gill, differences of Hg in muscle, and features noted for the remaining metals in examined tissues, biomonitoring should incorporate both crayfish and fish to produce more relevant water quality surveys.

Nitrogen accumulation profiles of selected grain and vegetable crops: A bibliography (1940-1992)

Energy Technology Data Exchange (ETDEWEB)

Meischen, S.J.; Byrd, K.R.

1994-10-01

A bibliography of nitrogen accumulation profile data for 25 vegetable and grain crops reported between 1940 and 1992 is presented. The selected crops are asparagus, broccoli, brussels sprouts, cabbage, carrots, cauliflower, celery, corn, cotton, cucumber, field bean, field pea, garlic, lettuce, onions, and peppers.

Assessment of micro, macro, toxic elements (Cd, Hg, Pb) and fatty acids profile in consumed fish commercially available in Cananeia and Cubatao, Sao Paulo State

International Nuclear Information System (INIS)

Curcho, Michel Rodrigues da Silva Morales

2009-01-01

Aside from their nutritional importance, fish are considered one of the most important bio indicators in aquatic systems for the estimation of pollution levels by toxic metals. This is so, since fish can bio accumulate these elements and they occupy different trophic levels and present different sizes and age. The purpose of the present study was to contribute with important data for the knowledge of nutritional and toxic constituents in muscles of the most consumed fish species from two coastal regions, Cananeia and Cubatao. Cananeia fish species analyzed were: Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Centropomus undecimalis (Robalo peba) and Mugil platanus (Tainha). From Cubatao, Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Menticirrhus americanus (Perna de moca), Sardella braziliensis (Sardinha) and Mugil liza (Tainha). For this study, analytical methodologies were developed and validated, regarding precision and accuracy, by means of certified reference materials. Micronutrients (Ca, Fe, K, Na, Se and Zn) and some trace elements (As, Br, Co, Cr, Rb) in fish muscle were determined by means of neutron activation analysis (NAA). Cold Vapor Atomic Absorption Spectrometry (CV AAS) was used for total Hg determination and Electrothermal Atomic Absorption Spectrometry (ET AAS) for Cd and Pb determinations. Proximate composition determinations according to AOAC methodologies and fatty acids profiles by gas chromatography were done in these muscle fish samples. Regarding fatty acids profile from the ω-6 family, Tainha species pool presented the highest values (8.9%) and Pescada species pool the lowest ones (4.4%) for Cananeia species. Fatty acids from the ω-3 family, Sardinha pool species presented the highest values (31.8%) for all species analyzed. Regarding micronutrients content great concentration variations between individual of the same species and between different species were observed. Discriminate analysis was used

Erato polymnioides - A novel Hg hyperaccumulator plant in ecuadorian rainforest acid soils with potential of microbe-associated phytoremediation.

Science.gov (United States)

Chamba, Irene; Rosado, Daniel; Kalinhoff, Carolina; Thangaswamy, Selvaraj; Sánchez-Rodríguez, Aminael; Gazquez, Manuel Jesús

2017-12-01

Mercury (Hg) accumulation capacity was assessed in three plant species (Axonopus compressus, Erato polymnioides, and Miconia zamorensis) that grow on soils polluted by artisanal small-scale gold mines in the Ecuadorian rainforest. Individuals of three species were collected at two sampling zones: i) an intensive zone (IZ, 4.8 mg Hg kg -1 of soil) where gold extraction continues to occur, and ii) a natural zone (NZ, 0.19 mg Hg kg -1 of soil). In addition, the percentage of arbuscular mycorrhizal fungi (AMF) colonization was determined in plant roots and seven fungal morphotypes isolated from rhizospheric soil. Results suggest a facilitation role of native and pollution adapted AMF on Hg phytoaccumulation. E.g., E. polymnioides increased Hg accumulation when growing with greater AMF colonization. We concluded that E. polymnioides is a good candidate for the design of microbe-assisted strategies for Hg remediation at gold mining areas. The consortia between E. polymnioides and the AMF isolated in this study could be instrumental to get a deeper understanding of the AMF role in Hg phytoaccumulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of sulfur on the accumulation of mercury in rice plant (Oryza sativa L.) growing in mercury contaminated soils.

Science.gov (United States)

Li, Yunyun; Zhao, Jiating; Guo, Jingxia; Liu, Mengjiao; Xu, Qinlei; Li, Hong; Li, Yu-Feng; Zheng, Lei; Zhang, Zhiyong; Gao, Yuxi

2017-09-01

Sulfur (S) is an essential element for plant growth and its biogeochemical cycling is strongly linked to the species of heavy metals in soil. In this work, the effects of S (sulfate and elemental sulfur) treatment on the accumulation, distribution and chemical forms of Hg in rice growing in Hg contaminated soil were investigated. It was found that S could promote the formation of iron plaque on the root surface and decrease total mercury (T-Hg) and methylmercury (MeHg) accumulation in rice grains, straw, and roots. Hg in the root was dominated in the form of RS-Hg-SR. Sulfate treatment increased the percentage of RS-Hg-SR to T-Hg in the rice root and changed the Hg species in soil. The dominant Hg species (70%) in soil was organic substance bound fractions. Sulfur treatment decreased Hg motility in the rhizosphere soils by promoting the conversion of RS-Hg-SR to HgS. This study is significant since it suggests that low dose sulfur treatment in Hg-containing water irrigated soil can decrease both T-Hg and MeHg accumulation in rice via inactivating Hg in the soil and promoting the formation of iron plaque in rice root, which may reduce health risk for people consuming those crops. Copyright © 2017. Published by Elsevier Ltd.

Hg0 and HgCl2 Reference Gas Standards: ?NIST Traceability ...

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the true concentrations of Hg0 and HgCl2 reference gases produced from high quality, NIST-traceable, commercial Hg0 and HgCl2 generators. This presentation will also discuss the availability of HCl and Hg0 compressed reference gas standards as a result of EPA's recently approved Alternative Methods 114 and 118. Gaseous elemental mercury (Hg0) and oxidized mercury (HgCl2) reference standards are integral to the use of mercury continuous emissions monitoring systems (Hg CEMS) for regulatory compliance emissions monitoring. However, a quantitative disparity of approximately 7-10% has been observed between commercial Hg0 and HgCl2 reference gases which currently limits the use of (HgCl2) reference gas standards. Resolving this disparity would enable the expanded use of (HgCl2) reference gas standards for regulatory compliance purposes.

Methylation of Hg downstream from the Bonanza Hg mine, Oregon

Science.gov (United States)

Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn

2012-01-01

Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream

Overexpression of PtABCC1 contributes to mercury tolerance and accumulation in Arabidopsis and poplar.

Science.gov (United States)

Sun, Liping; Ma, Yifeng; Wang, Huihong; Huang, Weipeng; Wang, Xiaozhu; Han, Li; Sun, Wanmei; Han, Erqin; Wang, Bangjun

2018-03-18

Mercury (Hg) is a highly biotoxic heavy metal that contaminates the environment. Phytoremediation is a green technology for environmental remediation and is used to clean up Hg contaminated soil in recent years. In this study, we isolated an ATP-binding cassette (ABC) transporter gene PtABCC1 from Populus trichocarpa and overexpressed it in Arabidopsis and poplar. The transgenic plants conferred higher Hg tolerance than wild type (WT) plants, and overexpression of PtABCC1 could lead to 26-72% or 7-160% increase of Hg accumulation in Arabidopsis or poplar plants, respectively. These results demonstrated that PtABCC1 plays a crucial role in enhancing tolerance and accumulation to Hg in plants, which provides a promising way for phytoremediation of Hg contamination. Copyright © 2018 Elsevier Inc. All rights reserved.

Screening of native plant species for phytoremediation potential at a Hg-contaminated mining site.

Science.gov (United States)

Marrugo-Negrete, José; Marrugo-Madrid, Siday; Pinedo-Hernández, José; Durango-Hernández, José; Díez, Sergi

2016-01-15

Artisanal and small-scale gold mining (ASGM) is the largest sector of demand for mercury (Hg), and therefore, one of the major sources of Hg pollution in the environment. This study was conducted in the Alacrán gold-mining site, one of the most important ASGM sites in Colombia, to identify native plant species growing in Hg-contaminated soils used for agricultural purposes, and to assess their potential as phytoremediation systems. Twenty-four native plant species were identified and analysed for total Hg (THg) in different tissues (roots, stems, and leaves) and in underlying soils. Accumulation factors (AF) in the shoots, translocation (TF) from roots to shoots, and bioconcentration (BCF) from soil-to-roots were determined. Different tissues from all plant species were classified in the order of decreasing accumulation of Hg as follows: roots > leaves > stems. THg concentrations in soil ranged from 230 to 6320 ng g(-1). TF values varied from 0.33 to 1.73, with high values in the lower Hg-contaminated soils. No correlation was found between soils with low concentrations of Hg and plant leaves, indicating that TF is not a very accurate indicator, since most of the Hg input to leaves at ASGM sites comes from the atmosphere. On the other hand, the BCF ranged from 0.28 to 0.99, with Jatropha curcas showing the highest value. Despite their low biomass production, several herbs and sub-shrubs are suitable for phytoremediation application in the field, due to their fast growth and high AF values in large and easily harvestable plant parts. Among these species, herbs such as Piper marginathum and Stecherus bifidus, and the sub-shrubs J. curcas and Capsicum annuum are promising native plants with the potential to be used in the phytoremediation of soils in tropical areas that are impacted by mining.

196Hg and 202Hg isotopic ratios in chondrites: revisited

International Nuclear Information System (INIS)

Jovanovic, S.; Reed, G.W. Jr.

1976-01-01

Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce 196 Hg and 202 Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly. (Auth.)

HG ion thruster component testing

Science.gov (United States)

Mantenieks, M. A.

1979-01-01

Cathodes, isolators, and vaporizers are critical components in determining the performance and lifetime of mercury ion thrusters. The results of life tests of several of these components are reported. A 30-cm thruster CIV test in a bell jar has successfully accumulated over 26,000 hours. The cathode has undergone 65 restarts during the life test without requiring any appreciable increases in starting power. Recently, all restarts have been achieved with only the 44 volt keeper supply with no change required in the starting power. Another ongoing 30-cm Hg thruster cathode test has successfully passed the 10,000 hour mark. A solid-insert, 8-cm thruster cathode has accumulated over 4,000 hours of thruster operation. All starts have been achieved without the use of a high voltage ignitor. The results of this test indicate that the solid impregnated insert is a viable neutralizer cathode for the 8-cm thruster.

Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean

International Nuclear Information System (INIS)

Dirtu, Alin C.; Malarvannan, Govindan; Das, Krishna; Dulau-Drouot, Violaine; Kiszka, Jeremy J.; Lepoint, Gilles; Mongin, Philippe; Covaci, Adrian

2016-01-01

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ 13 C and δ 15 N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ 15 N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation. - Highlights: • POPs and total Hg were

Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean

Energy Technology Data Exchange (ETDEWEB)

Dirtu, Alin C. [Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Department of Chemistry, “Al. I. Cuza” University of Iasi, 700506 Iasi (Romania); Malarvannan, Govindan [Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Das, Krishna [University of Liege, MARE Center, Laboratory for Oceanology, 4000 Liege (Belgium); Dulau-Drouot, Violaine [Groupe Local d’Observation et d’Identification des Cétacés (GLOBICE), 30 Chemin Parc Cabris, Grand Bois, 97410 Saint Pierre, La Réunion (France); Kiszka, Jeremy J. [Marine Sciences Program, Department of Biological Sciences, Florida International University, 3000 NE 151st, North Miami, FL 33181 (United States); Lepoint, Gilles [University of Liege, MARE Center, Laboratory for Oceanology, 4000 Liege (Belgium); Mongin, Philippe [Brigade Nature Océan Indien (BNOI)/ONCFS, 12 Allée de la Foret – Parc de la Providence, 97400 Saint Denis, La Réunion (France); Covaci, Adrian, E-mail: adrian.covaci@uantwerpen.be [Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium)

2016-04-15

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ{sup 13}C and δ{sup 15}N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ{sup 15}N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation. - Highlights: • POPs and total

A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions

International Nuclear Information System (INIS)

Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.

2005-01-01

A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru

Ultrasensitive detection of Hg2+ using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

International Nuclear Information System (INIS)

Cheng, Junjie; Li, Jiadong; Miao, Bin; Wu, Dongmin; Wang, Jine; Pei, Renjun; Wu, Zhengyan

2014-01-01

An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg 2+ . The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg 2+ and thymines were combined. The current response of this Hg 2+ ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg 2+ ions on the surface by the highly specific thymine-Hg 2+ -thymine recognition. The dynamic linear range for Hg 2+ detection has been determined in the concentrations from 10 −14 to 10 −8 M and a detection limit below 10 −14 M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg 2+ detection till now.

Selenium deficiency-induced alterations in ion profiles in chicken muscle.

Directory of Open Access Journals (Sweden)

Haidong Yao

Full Text Available Ion homeostasis plays important roles in development of metabolic diseases. In the present study, we examined the contents and distributions of 25 ions in chicken muscles following treatment with selenium (Se deficiency for 25 days. The results revealed that in chicken muscles, the top ranked microelements were silicon (Si, iron (Fe, zinc (Zn, aluminum (Al, copper (Cu and boron (B, showing low contents that varied from 292.89 ppb to 100.27 ppm. After Se deficiency treatment, essential microelements [Cu, chromium (Cr, vanadium (V and manganese (Mn], and toxic microelements [cadmium (Cd and mercury (Hg] became more concentrated (P < 0.05. Elements distribution images showed generalized accumulation of barium (Ba, cobalt (Co, Cu, Fe and V, while Cr, Mn, and Zn showed pin point accumulations in muscle sections. Thus, the ion profiles were generally influenced by Se deficiency, which suggested a possible role of Se deficiency in muscle dysfunctions caused by these altered ion profiles.

Mercury distribution in the foliage and soil profiles of the Tibetan forest: Processes and implications for regional cycling

International Nuclear Information System (INIS)

Gong, Ping; Wang, Xiao-ping; Xue, Yong-gang; Xu, Bai-qing; Yao, Tan-dong

2014-01-01

Remote forests are considered a pool of Mercury (Hg) in the global Hg cycle. However, notably few studies have investigated the fate of Hg in the Tibetan forest. In this study, fifty-two foliage samples and seven litter/soil profiles were collected throughout the Tibetan forest. The concentrations of total Hg (THg) in foliage were positively correlated with longitude and negatively correlated with altitude, indicating that the emission of Hg is expected to decrease with increasing distance from emission sources to the Tibetan forest. The deposition flux of THg in the Tibetan forest (with an air-to-forest ground flux of 9.2 μg/m 2 /year) is ∼2 times the flux in clearings, which is suggestive of enhanced Hg deposition by the forest. The depositional Hg is eventually stored in the forest soil, and the soil acts as a net ‘sink’ for Hg. - Highlights: • Foliage can be used as bio-indicator for monitoring the spatial Hg distribution. • The Tibetan forest can enhance the atmospheric Hg deposition to the ground. • The Tibetan forest soil is a pool of Hg that acts to delay the regional cycling of Hg. - The Tibetan forest can accumulate atmospheric Hg, which undergoes long-range transport, and the soil of Tibetan forest acts as the final Hg ‘sink’

Induction by mercury compounds of brain metallothionein in rats: Hg{sup 0} exposure induces long-lived brain metallothionein

Energy Technology Data Exchange (ETDEWEB)

Yasutake, Akira; Nakano, Atsuhiro [Biochemistry Section, National Institute for Minamata Disease, Kumamoto (Japan); Hirayama, Kimiko [Kumamoto University, College of Medical Science (Japan)

1998-03-01

Metallothionein (MT) is one of the stress proteins which can easily be induced by various kind of heavy metals. However, MT in the brain is difficult to induce because of blood-brain barrier impermeability to most heavy metals. In this paper, we have attempted to induce brain MT in rats by exposure to methylmercury (MeHg) or metallic mercury vapor, both of which are known to penetrate the blood-brain barrier and cause neurological damage. Rats treated with MeHg (40 {mu}mol/kg per day x 5 days, p.o.) showed brain Hg levels as high as 18 {mu}g/g with slight neurological signs 10 days after final administration, but brain MT levels remained unchanged. However, rats exposed to Hg vapor for 7 days showed 7-8 {mu}g Hg/g brain tissue 24 h after cessation of exposure. At that time brain MT levels were about twice the control levels. Although brain Hg levels fell gradually with a half-life of 26 days, MT levels induced by Hg exposure remained unchanged for >2 weeks. Gel fractionation revealed that most Hg was in the brain cytosol fraction and thus bound to MT. Hybridization analysis showed that, despite a significant increase in MT-I and -II mRNA in brain, MT-III mRNA was less affected. Although significant Hg accumulation and MT induction were observed also in kidney and liver of Hg vapor-exposed rats, these decreased more quickly than in brain. The long-lived MT in brain might at least partly be accounted for by longer half-life of Hg accumulated there. The present results showed that exposure to Hg vapor might be a suitable procedure to provide an in vivo model with enhanced brain MT. (orig.) With 4 figs., 1 tab., 27 refs.

Sediment mixing and accumulation rate effects on radionuclide depth profiles in Hudson estuary sediments

International Nuclear Information System (INIS)

Olsen, C.R.; Simpson, H.J.; Peng, T.; Bopp, R.F.; Trier, R.M.

1981-01-01

Measured anthropogenic radionuclide profiles in sediment cores from the Hudson River estuary were compared with profiles computed by using known input histories of radionuclides to the estuary and mixing coefficients which decreased exponentially with depth in the sediment. Observed 134 Cs sediment depth profiles were used in the mixing rate computation because reactor releases were the only significant source for this nuclide, whereas the inputs of 137 Cs and /sup 239.240/Pu to the estuary were complicated by runoff or erosion in upstream areas, in addition to direct fallout from precipitation. Our estimates for the rates of surface sediment mixing in the low salinity reach of the estuary range from 0.25 to 1 cm 2 /yr, or less. In some areas of the harbor adjacent to New York City, were fine-particle accumulation rates are generally >3 cm/yr, and often as high as 10 to 20 cm/yr, sediment mixing rates as high as 10 cm 2 /yr would have little effect on radionuclide peak distributions. Consequently, anthropogenic radionuclide maximum activities in subsurface sediments of the Hudson appear to be useful as time-stratigraphic reference levels, which can be correlated with periods of maximum radionuclide inputs for estimating rates and patterns of sediment accumulation

Looking for biomarkers of Hg exposure by transcriptome analysis in the aquatic plant Elodea nuttallii

Directory of Open Access Journals (Sweden)

Regier N.

2013-04-01

Full Text Available Recently developed genomics tools have a promising potential to identify early biomarkers of exposure to toxicants. In the present work we used transcriptome analysis (RNA-seq of Elodea nuttallii –an invasive rooted macrophyte that is able to accumulate large amounts of metals- to identify biomarkers of Hg exposure. RNA-seq allowed identification of genes affected by Hg exposure and also unraveled plant response to the toxic metal: a change in energy/reserve metabolism caused by the inhibition of photosynthesis, and an adaptation of homeostasis networks to control accumulation of Hg. Data were validated by RT-qPCR and selected genes were further tested as biomarkers. Samples exposed in the field and to natural contaminated sediments clustered well with samples exposed to low metal concentrations under laboratory conditions. Our data suggest that this plant and/or this approach could be useful to develop new tests for water and sediment quality assessment.

199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides

International Nuclear Information System (INIS)

Wurtinger, W.; Kankeleit, E.

1979-01-01

The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)

Ecological effects of some heavy metals (Cd, Pb, Hg, Cr) pollution of ...

African Journals Online (AJOL)

STORAGESEVER

2008-06-17

Jun 17, 2008 ... Accumulation of heavy metals (Cd, Pb, Hg, Cr) in water and plankton of Sarıyar Dam Lake (SDR) was seasonally ... human impacts in protected areas with the aim of .... (1999), heavy metals toxicity is affected by temperature,.

Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.

Science.gov (United States)

Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender

2016-05-01

Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

Biochar amendment reduced methylmercury accumulation in rice plants.

Science.gov (United States)

Shu, Rui; Wang, Yongjie; Zhong, Huan

2016-08-05

There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1-4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49-92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35-79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment. Copyright © 2016 Elsevier B.V. All rights reserved.

Body Burden of Hg in Different Bio-Samples of Mothers in Shenyang City, China

Science.gov (United States)

Xu, Jian; Du, Juan; Yan, Chong-huai

2014-01-01

Hg is an accumulative and neuro-toxic heavy metal which has a wide range of adverse effects in human health. However, few studies are available on body burden of Hg level in different bio-samples of pregnant women in Chinese population. Therefore, this study evaluated Hg levels in different maternal bio-samples in Shenyang city, China and investigated the correlation of Hg levels in different bio-samples. From October to December 2008, 200 pregnant women about to deliver their babies at ShengJing Hospital (Shenyang city, northeast of China) participated in this study. The geometric mean (GM) of Hg levels in cord blood, maternal venous blood, breast milk, and maternal urine were 2.18 µg/L, 1.17 µg/L, 1.14 µg/L, and 0.73 µg/L, respectively, and the GM of maternal hair Hg level was 404.45 µg/kg. There was a strong correlation between cord blood and maternal blood total Hg level (r = 0.713, PHg exposure (unadjusted OR 3.5, adjusted OR 2.94, PHg burden of mothers and the risk factors of prenatal Hg exposure in Shenyang city, China. PMID:24858815

Metallothionein expression in chloroplasts enhances mercury accumulation and phytoremediation capability

OpenAIRE

Ruiz, Oscar N.; Alvarez, Derry; Torres, Cesar; Roman, Laura; Daniell, Henry

2011-01-01

Genetic engineering to enhance mercury phytoremediation has been accomplished by expression of the merAB genes that protects the cell by converting Hg[II] into Hg[0] which volatilizes from the cell. A drawback of this approach is that toxic Hg is released back into the environment. A better phytoremediation strategy would be to accumulate mercury inside plants for subsequent retrieval. We report here the development of a transplastomic approach to express the mouse metallothionein gene (mt1) ...

Accumulation of heavy metals in soil-crop systems: a review for wheat and corn.

Science.gov (United States)

Wang, Shiyu; Wu, Wenyong; Liu, Fei; Liao, Renkuan; Hu, Yaqi

2017-06-01

The health risks arising from heavy metal pollution (HMP) in agricultural soils have attracted global attention, and research on the accumulation of heavy metals in soil-plant systems is the basis for human health risk assessments. This review studied the accumulation of seven typical heavy metals-Cd, Cr, As, Pb, Hg, Cu, and Zn-in soil-corn and soil-wheat systems. The findings indicated that, in general, wheat was more likely to accumulate heavy metals than corn. Bioconcentration factor (BCF) of the seven heavy metals in wheat and corn grains decreased exponentially with their average concentrations in soil. The seven heavy metals were ranked as follows, in ascending order of accumulation in corn grains: Pb < Cr < Zn < As < Cu < Cd <Hg. As for the order of accumulation in wheat grains, their ranking was as follows: Zn < Pb < Cr < Cu < As < Hg Hg, Cu, and Zn in corn grains were 0.054, 6.65 × 10 -4 , 7.94 × 10 -4 , 0.0044, 0.028, 0.13, and 0.19, respectively. The corresponding BCFs values for wheat grains were 0.25, 0.0045, 5.42 × 10 -4 , 0.009, 4.03 × 10 -4 , 0.11, and 0.054, respectively.

Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

KAUST Repository

Marques, Ana

2016-02-24

The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system’s health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing

Formation of Hg(II) Tetrathiolate Complexes with Cysteine at Neutral pH.

Science.gov (United States)

Warner, Thomas; Jalilehvand, Farideh

2016-04-01

Mercury(II) ions precipitate from aqueous cysteine (H 2 Cys) solutions containing H 2 Cys/Hg(II) mole ratio ≥ 2.0 as Hg( S -HCys) 2 . In absence of additional cysteine, the precipitate dissolves at pH ~12 with the [Hg( S,N -Cys) 2 ] 2- complex dominating. With excess cysteine (H 2 Cys/Hg(II) mole ratio ≥ 4.0), higher complexes form and the precipitate dissolves at lower pH values. Previously, we found that tetrathiolate [Hg( S -Cys) 4 ] 6- complexes form at pH = 11.0; in this work we extend the investigation to pH values of physiological interest. We examined two series of Hg(II)-cysteine solutions in which C Hg(II) varied between 8 - 9 mM and 80 - 100 mM, respectively, with H 2 Cys/Hg(II) mole ratios from 4 to ~20. The solutions were prepared in the pH range 7.1 - 8.8, at the pH at which the initial Hg( S -HCys) 2 precipitate dissolved. The variations in the Hg(II) speciation were followed by 199 Hg NMR, X-ray absorption and Raman spectroscopic techniques. Our results show that in the dilute solutions ( C Hg(II) = 8 - 9 mM), mixtures of di-, tri- (major) and tetrathiolate complexes exist at moderate cysteine excess ( C H2Cys ~ 0.16 M) at pH 7.1. In the more concentrated solutions ( C Hg(II) = 80 - 100 mM) with high cysteine excess ( C H2Cys > 0.9 M), tetrathiolate [Hg( S -cysteinate) 4 ] m -6 ( m = 0 - 4) complexes dominate in the pH range 7.3 - 7.8, with lower charge than for the [Hg( S -Cys) 4 ] 6- complex due to protonation of some ( m ) of the amino groups of the coordinated cysteine ligands. The results of this investigation could provide a key to the mechanism of biosorption and accumulation of Hg(II) ions in biological / environmental systems.

Massive accumulation of highly polluted sedimentary deposits by river damming

Energy Technology Data Exchange (ETDEWEB)

Palanques, Albert, E-mail: albertp@icm.csic.es [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain); Grimalt, Joan [Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona, 18, Barcelona 08034 (Spain); Belzunces, Marc; Estrada, Ferran; Puig, Pere; Guillén, Jorge [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain)

2014-11-01

Uncontrolled dumping of anthropogenic waste in rivers regulated by dams has created contaminated deposits in reservoirs that have remained unidentified for decades. The Flix Reservoir is located in the Ebro River, the second largest river flowing into the NW Mediterranean, has been affected by residue dumping from a chlor-alkali electrochemical plant for decades. High-resolution seismic profiles, bathymetric data, surficial sediment samples and sediment cores were obtained in the Flix Reservoir to study the characteristics of the deposit accumulated by this dumping. These data were used to reconstruct the waste deposit history. Since the construction of the Flix Dam in 1948, more than 3.6 × 10{sup 5} t of industrial waste has accumulated in the reservoir generating a delta-like deposit formed by three sediment lobes of fine-grained material highly contaminated by Hg, Cd, Zn and Cr (max: 640, 26, 420 and 750 mg kg{sup −1}, respectively). This contamination was associated with the Hg that was used for the cathode in the electrochemical plant from 1949 and with the production of phosphorite derivatives from 1973. After the construction of two large dams only a few kilometres upstream during the 1960s, the solids discharged from the industrial complex became the main sediment source to the Flix Reservoir. The deposit has remained in the reservoir forming a delta that obstructs about 50% of the river water section. Its stability only depended on the flow retention by the Flix Dam. At present, this contaminated waste deposit is being removed from the water reservoir as it is a cause of concern for the environment and for human health downriver. - Highlights: • A delta-like anthropogenic deposit prograded into the reservoir behind the Flix dam. • More than 3.6 × 10{sup 5} t of anthropogenic waste was accumulated in less than 4 decades. • A waste deposit with extreme levels of Hg and Cd was trapped in the Flix Reservoir. • The main pollution was related to

Total mercury and methyl-mercury contents and accumulation in polar microbial mats.

Science.gov (United States)

Camacho, Antonio; Rochera, Carlos; Hennebelle, Raphaëlle; Ferrari, Christophe; Quesada, Antonio

2015-03-15

Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them, we have measured Hg concentrations in microbial mats that were collected from 6 locations in different ecological situations. For this purpose, the direct anthropogenic impacts, volcanic influences, proximity to the seashore, latitudinal gradients and C contents were investigated. Our results show that, other than the direct anthropogenic influence, none of the other hypotheses alone satisfactorily explains the Hg content in microbial mats. In contrast, the MeHg contents were noticeably different between the investigated locations, with a higher proportion of MeHg on the McMurdo Ice Shelf (Antarctica) and a lower proportion on Ward Hunt Island (High Arctic). Furthermore, our results from in situ experiments indicated that the microbial mats from South Shetland Islands could quickly accumulate (48 h) Hg when Hg dissolved salts were supplied. Over short-term periods, these mats do not transform Hg into MeHg under field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Body burden of Hg in different bio-samples of mothers in Shenyang city, China.

Directory of Open Access Journals (Sweden)

Min-Ming Li

Full Text Available Hg is an accumulative and neuro-toxic heavy metal which has a wide range of adverse effects in human health. However, few studies are available on body burden of Hg level in different bio-samples of pregnant women in Chinese population. Therefore, this study evaluated Hg levels in different maternal bio-samples in Shenyang city, China and investigated the correlation of Hg levels in different bio-samples. From October to December 2008, 200 pregnant women about to deliver their babies at ShengJing Hospital (Shenyang city, northeast of China participated in this study. The geometric mean (GM of Hg levels in cord blood, maternal venous blood, breast milk, and maternal urine were 2.18 µg/L, 1.17 µg/L, 1.14 µg/L, and 0.73 µg/L, respectively, and the GM of maternal hair Hg level was 404.45 µg/kg. There was a strong correlation between cord blood and maternal blood total Hg level (r = 0.713, P<0.001. Frequency of fish consumption more than or equal to 3 times per week during pregnancy was suggested as a significant risk factor of prenatal Hg exposure (unadjusted OR 3.5, adjusted OR 2.94, P<0.05. This study provides evidence about Hg burden of mothers and the risk factors of prenatal Hg exposure in Shenyang city, China.

Studies of the 198Hg(d,d') and 198Hg(d,p) reactions

Science.gov (United States)

Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

2017-09-01

Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.

Incorporation of radiometric tracers in peat and implications for estimating accumulation rates

Energy Technology Data Exchange (ETDEWEB)

Hansson, Sophia V., E-mail: sophia.hansson@emg.umu.se [Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå (Sweden); Kaste, James M. [Geology Department, The College of William and Mary, Williamsburg, VA 23187 (United States); Olid, Carolina; Bindler, Richard [Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå (Sweden)

2014-09-15

Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides {sup 210}Pb, {sup 137}Cs, {sup 241}Am, and {sup 7}Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of {sup 7}Be down to 18–20 cm for some cores, and the broad vertical distribution of {sup 241}Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m{sup −2} yr{sup −1}), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of {sup 210}Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m{sup −2} yr{sup −1}) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using {sup 7}Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years. - Highlights: • {sup 210}Pb, {sup 137}Cs, {sup 241}Am and {sup 7}Be, and tot-Pb and tot Hg were measured in 5 peat cores. • Two age–depth models were applied resulting in different accumulation rates

Biochar amendment reduced methylmercury accumulation in rice plants

Energy Technology Data Exchange (ETDEWEB)

Shu, Rui; Wang, Yongjie [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Zhong, Huan, E-mail: zhonghuan@nju.edu.cn [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario (Canada)

2016-08-05

Highlights: • Biochar amendment could evidently reduce methylmercury (MeHg) levels in rice grain. • Biochar could enhance microbial production of MeHg, probably by providing sulfate. • Biochar could immobilize MeHg in soil, and reduce MeHg availability to rice plants. • Biochar amendment increased grain biomass, leading to biodilution of MeHg in grain. - Abstract: There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1–4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49–92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35–79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.

Biochar amendment reduced methylmercury accumulation in rice plants

International Nuclear Information System (INIS)

Shu, Rui; Wang, Yongjie; Zhong, Huan

2016-01-01

Highlights: • Biochar amendment could evidently reduce methylmercury (MeHg) levels in rice grain. • Biochar could enhance microbial production of MeHg, probably by providing sulfate. • Biochar could immobilize MeHg in soil, and reduce MeHg availability to rice plants. • Biochar amendment increased grain biomass, leading to biodilution of MeHg in grain. - Abstract: There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1–4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49–92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35–79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.

46 CFR 53.12-1 - General (modifies HG-600 through HG-640).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false General (modifies HG-600 through HG-640). 53.12-1... HEATING BOILERS Instruments, Fittings, and Controls (Article 6) § 53.12-1 General (modifies HG-600 through HG-640). (a) The instruments, fittings and controls for heating boilers shall be as indicated in HG...

A functional graphene oxide-ionic liquid composites-gold nanoparticle sensing platform for ultrasensitive electrochemical detection of Hg2+.

Science.gov (United States)

Zhou, Na; Li, Jinhua; Chen, Hao; Liao, Chunyang; Chen, Lingxin

2013-02-21

A simple and sensitive electrochemical assay strategy of stripping voltammetry for mercury ions (Hg(2+)) detection is described based on the synergistic effect between ionic liquid functionalized graphene oxide (GO-IL) and gold nanoparticles (AuNPs). The AuNPs-GO-IL modified onto glassy carbon electrode (GCE) resulted in highly enhanced electron conductive nanostructured membrane and large electroactive surface area, which was excellently examined by scanning electron microscopy and cyclic voltammetry. After accumulating Hg(2+), anodic stripping voltammetry (ASV) was performed, and differential pulse voltammetry (DPV) was employed for signal recording of Hg(2+). Several main experimental parameters were optimized, i.e., deposition potential and time of AuNPs were -0.2 V and 180 s, respectively, and accumulation potential and time of Hg(2+) were -0.3 V and 660 s, respectively. Under the optimal conditions, this AuNPs-GO-IL-GCE sensor attained a good linearity in a wide range of 0.1-100 nM (R = 0.9808) between the concentration of the Hg(2+) standard and peak current. The limit of detection was estimated to be 0.03 nM at a signal-to-noise ratio of 3σ. A variety of common coexistent ions in water samples were investigated, showing no obvious interferences on the Hg(2+) detection. The practical application of the proposed sensor has been carried out and demonstrated as feasible for determination of trace levels of Hg(2+) in drinking and environmental water samples.

Accumulation of mercury in selected plant species grown in soils contaminated with different mercury compounds

International Nuclear Information System (INIS)

Su, Yi; Han, Fengxiang; Shiyab, Safwan; Chen, Jian; Monts, David L.

2007-01-01

The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl 2 , and Hg(NO 3 ) 2 , were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots ( 2 powder, respectively; no visual stress symptoms were observed. We also studied mercury phyto-remediation using aged soils that contained HgS, HgCl 2 , or Hg(NO 3 ) 2 . We have found that up to hundreds

Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

1984-01-01

The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

Tracing aquatic bioavailable Hg in three different regions of China using fish Hg isotopes.

Science.gov (United States)

Liu, Cheng-Bin; Hua, Xiu-Bing; Liu, Hong-Wei; Yu, Ben; Mao, Yu-Xiang; Wang, Ding-Yong; Yin, Yong-Guang; Hu, Li-Gang; Shi, Jian-Bo; Jiang, Gui-Bin

2018-04-15

To trace the most concerned bioavailable mercury (Hg) in aquatic environment, fish samples were collected from three typical regions in China, including 3 rivers and 1 lake in the Tibetan Plateau (TP, a high altitude background region with strong solar radiation), the Three Gorges Reservoir (TGR, the largest artificial freshwater reservoir in China), and the Chinese Bohai Sea (CBS, a heavily human-impacted semi-enclosed sea). The Hg isotopic compositions in fish muscles were analyzed. The results showed that anthropogenic emissions were the main sources of Hg in fish from TGR and CBS because of the observed negative δ 202 Hg and positive Δ 199 Hg in these two regions (TGR, δ 202 Hg: - 0.72 to - 0.29‰, Δ 199 Hg: 0.15 - 0.52‰; CBS, δ 202 Hg: - 2.09 to - 0.86‰, Δ 199 Hg: 0.07 - 0.52‰). The relatively higher δ 202 Hg and Δ 199 Hg (δ 202 Hg: - 0.37 - 0.08‰, Δ 199 Hg: 0.50 - 1.89‰) in fish from TP suggested the insignificant disturbance from local anthropogenic activities. The larger slopes of Δ 199 Hg/Δ 201 Hg in fish from TGR (1.29 ± 0.14, 1SD) and TP (1.25 ± 0.06, 1SD) indicated methylmercury (MeHg) was produced and photo-reduced in the water column before incorporation into the fish. In contrast, the photoreduction of Hg 2+ was the main process in CBS (slope of Δ 199 Hg/Δ 201 Hg: 1.06 ± 0.06, 1SD). According to the fingerprint data of Hg isotopes, the most important source for aquatic bioavailable Hg in TP should be the long-range transported Hg, contrasting to the anthropogenic originated MeHg from surface sediments and runoffs in TGR and inorganic Hg from continental inputs in CBS. Therefore, the isotopic signatures of Hg in fish can provide novel clues in tracing sources and behaviors of bioavailable Hg in aquatic systems, which are critical for further understanding the biogeochemical cycling of Hg. Copyright © 2017 Elsevier Inc. All rights reserved.

Protein changes in Lepidium sativum L. exposed to Hg during soil phytoremediation.

Science.gov (United States)

Smolinska, Beata; Szczodrowska, Agnieszka; Leszczynska, Joanna

2017-08-03

Some investigations have been carried out in this study to find the best technique of soil reclamation in mercurypolluted soil. In this study, we examined Lepidium sativum L. as a plant useful for Hg phytoextraction. The simultaneous application of compost and thiosulfate was explored as a possible method of enhancing the process of phytoextraction. The results of the investigations of plant protein changes during assisted Hg phytoextraction were also provided. The results of the study show that combined use of compost and thiosulfate significantly increased both the total Hg accumulation and its translocation to aerial plant tissues. Plant protein analysis showed that L. sativum L. has the ability to respond to environmental stress condition by the activation of additional proteins. The additional proteins, like homocysteine methyltransferase, ribulose bisphosphate carboxylases (long and short chains), 14-3-3-like protein, and biosynthesis-related 40S ribosomal protein S15, were activated in plant shoots only in experiments carried out in Hg-polluted soil. There were no protein changes observed in plants exposed to compost and thiosulfate. It suggests that the combined use of compost and thiosulfate decreased Hg toxicity.

Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India.

Science.gov (United States)

Rai, Prabhat Kumar; Tripathi, B D

2009-01-01

The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L(-1). The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R(2) = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO(3-) and PO(4)(3-)) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.

Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

Science.gov (United States)

Burke, Samantha M.; Zimmerman, Christian E.; Branfireun, Brian A.; Koch, Joshua C.; Swanson, Heidi K.

2018-01-01

The biogeochemical cycle of mercury will be influenced by climate change, particularly at higher latitudes. Investigations of historical mercury accumulation in lake sediments inform future predictions as to how climate change might affect mercury biogeochemistry; however, in regions with a paucity of data, such as the thermokarst-rich Arctic Coastal Plain of Alaska (ACP), the trajectory of mercury accumulation in lake sediments is particularly uncertain. Sediment cores from three thermokarst lakes on the ACP were analyzed to understand changes in, and drivers of, Hg accumulation over the past ~ 100 years. Mercury accumulation in two of the three lakes was variable and high over the past century (91.96 and 78.6 µg/m2/year), and largely controlled by sedimentation rate. Mercury accumulation in the third lake was lower (14.2 µg/m2/year), more temporally uniform, and was more strongly related to sediment Hg concentration than sedimentation rate. Sediment mercury concentrations were quantitatively related to measures of sediment composition and VRS-inferred chlorophyll a, and sedimentation rates were related to various catchment characteristics. These results were compared to data from 37 previously studied Arctic and Alaskan lakes. Results from the meta-analysis indicate that thermokarst lakes have significantly higher and more variable Hg accumulation rates than non-thermokarst lakes, suggesting that certain properties (e.g., thermal erosion, thaw slumping, low hydraulic conductivity) likely make lakes prone to high and variable Hg accumulation rates. Differences and high variability in Hg accumulation among high latitude lakes highlight the complexity of predicting future climate-related change impacts on mercury cycling in these environments.

Equilibrium mercury isotope fractionation between dissolved Hg(II) species and thiol-bound Hg

NARCIS (Netherlands)

Wiederhold, Jan G.; Cramer, Christopher J.; Daniel, Kelly; Infante, Ivan; Bourdon, Bernard; Kretzschmar, Ruben

2010-01-01

Stable Hg isotope ratios provide a new tool to trace environmental Hg cycling. Thiols (-SH) are the dominant Hg-binding groups in natural organic matter. Here, we report experimental and computational results on equilibrium Hg isotope fractionation between dissolved Hg(II) species and thiol-bound

46 CFR 53.10-3 - Inspection and tests (modifies HG-500 through HG-540).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Inspection and tests (modifies HG-500 through HG-540... tests (modifies HG-500 through HG-540). (a) The inspections required by HG-500 through HG-540 must be performed by the “Authorized Inspector” as defined in HG-515 of section IV of the ASME Boiler and Pressure...

Spatial-temporal dynamics and sources of total Hg in a hydroelectric reservoir in the Western Amazon, Brazil.

Science.gov (United States)

Pestana, I A; Bastos, W R; Almeida, M G; de Carvalho, D P; Rezende, C E; Souza, C M M

2016-05-01

Damming rivers to construct hydroelectric reservoirs results in a series of impacts on the biogeochemical Hg cycle. For example, modifying the hydrodynamics of a natural watercourse can result in the suspension and transport of Hg deposits in the water column, which represents an exposure risk for biota. The objective of this study was to evaluate the influences of seasonality on the dispersion of total Hg in the Hydroelectric Power Plant (HPP)-Samuel Reservoir (Porto Velho/Brazil). Sampling campaigns were performed during the three following hydrological periods characteristic of the region: low (Oct/2011), ebbing (May/2012), and high (Feb/2013) water. Sediment profiles, suspended particulate matter (SPM), and aquatic macrophytes (Eicchornia crassipes and Oryza spp.) were collected, and their Hg concentrations and isotopic and elemental C and N signatures were determined. The drainage basin significantly influenced the SPM compositions during all the periods, with a small autochthonous influence from the reservoir during the low water. The highest SPM Hg concentrations inside the reservoir were observed during the high water period, suggesting that the hydrodynamics of this environment favor the suspension of fine SPM, which has a higher Hg adsorption capacity. The Hg concentrations in the sediment profiles were ten times lower than those in the SPM, indicating that large particles with low Hg concentrations were deposited to form the bottom sediment. Hg concentrations were higher in aquatic macrophyte roots than in their leaves and appeared to contribute to the formation of SPM during the low water period. In this environment, Hg transport mainly occurs in SPM from the Jamari River drainage basin, which is the primary source of Hg in this environment.

Comparative analysis on the effect of Lycopersicon esculentum (tomato) in reducing cadmium, mercury and lead accumulation in liver.

Science.gov (United States)

Nwokocha, Chukwuemeka R; Nwokocha, Magdalene I; Aneto, Imaria; Obi, Joshua; Udekweleze, Damian C; Olatunde, Bukola; Owu, Daniel U; Iwuala, Moses O

2012-06-01

L. esculentum (tomato) contain compounds with anti-oxidant and anti-inflammatory properties, able to synthesize metal chelating proteins. We examined the ability of fruit extract to protect against mercury (Hg), lead (Pb) and cadmium (Cd) accumulation in the liver. Rats were fed on tomato mixed with rat chow (10% w/w), while Hg (10 ppm), Cd (200 ppm) and Pb (100 ppm) was given in drinking water. Tomato was administered together with the metals (group 2), a week after exposure (group 3) or a week before metal exposure (group 4) for a period of six weeks. The metal accumulations in the liver were determined using AAS. There was a significant (Ptomato to Cd and Hg accumulation but not to Pb (PTomato reduces uptake while enhancing the elimination of these metals in a time dependent manner. The highest hepatoprotective effect was to Cd followed by Hg and least to Pb. Its administration is beneficial in reducing heavy metal accumulation in the liver. Copyright © 2012 Elsevier Ltd. All rights reserved.

R-2HG Exhibits Anti-tumor Activity by Targeting FTO/m6A/MYC/CEBPA Signaling.

Science.gov (United States)

Su, Rui; Dong, Lei; Li, Chenying; Nachtergaele, Sigrid; Wunderlich, Mark; Qing, Ying; Deng, Xiaolan; Wang, Yungui; Weng, Xiaocheng; Hu, Chao; Yu, Mengxia; Skibbe, Jennifer; Dai, Qing; Zou, Dongling; Wu, Tong; Yu, Kangkang; Weng, Hengyou; Huang, Huilin; Ferchen, Kyle; Qin, Xi; Zhang, Bin; Qi, Jun; Sasaki, Atsuo T; Plas, David R; Bradner, James E; Wei, Minjie; Marcucci, Guido; Jiang, Xi; Mulloy, James C; Jin, Jie; He, Chuan; Chen, Jianjun

2018-01-11

R-2-hydroxyglutarate (R-2HG), produced at high levels by mutant isocitrate dehydrogenase 1/2 (IDH1/2) enzymes, was reported as an oncometabolite. We show here that R-2HG also exerts a broad anti-leukemic activity in vitro and in vivo by inhibiting leukemia cell proliferation/viability and by promoting cell-cycle arrest and apoptosis. Mechanistically, R-2HG inhibits fat mass and obesity-associated protein (FTO) activity, thereby increasing global N 6 -methyladenosine (m 6 A) RNA modification in R-2HG-sensitive leukemia cells, which in turn decreases the stability of MYC/CEBPA transcripts, leading to the suppression of relevant pathways. Ectopically expressed mutant IDH1 and S-2HG recapitulate the effects of R-2HG. High levels of FTO sensitize leukemic cells to R-2HG, whereas hyperactivation of MYC signaling confers resistance that can be reversed by the inhibition of MYC signaling. R-2HG also displays anti-tumor activity in glioma. Collectively, while R-2HG accumulated in IDH1/2 mutant cancers contributes to cancer initiation, our work demonstrates anti-tumor effects of 2HG in inhibiting proliferation/survival of FTO-high cancer cells via targeting FTO/m 6 A/MYC/CEBPA signaling. Copyright © 2017 Elsevier Inc. All rights reserved.

Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

Energy Technology Data Exchange (ETDEWEB)

Cheng, Junjie [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Li, Jiadong; Miao, Bin; Wu, Dongmin, E-mail: dmwu2008@sinano.ac.cn [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wang, Jine; Pei, Renjun, E-mail: rjpei2011@sinano.ac.cn [Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

2014-08-25

An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup −14} to 10{sup −8} M and a detection limit below 10{sup −14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

Clams sensitivity towards As and Hg: A comprehensive assessment of native and exotic species.

Science.gov (United States)

Velez, Cátia; Freitas, Rosa; Antunes, Sara C; Soares, Amadeu M V M; Figueira, Etelvina

2016-03-01

To assess the environmental impact of As and Hg, bioindicator organisms such as bivalves have been used. Nevertheless, few studies have assessed the impacts of As and Hg in Ruditapes decussatus and Ruditapes philippinarum, which are native and exotic species in Europe, respectively. The main goal of the present study was to assess elements' partitioning and detoxification strategies of R. decussatus and R. philippinarum. Both clams showed a higher capacity to bioconcentrate Hg (BCF 2.29-7.49), when compared to As (0.59-1.09). Furthermore, As accumulation in both species was similar in the soluble and insoluble fractions, while in both species the majority of Hg was found in the insoluble fraction. Clams exposed to As showed different detoxification strategies, since R. decussatus had higher ability to enhance antioxidant enzymes and metallothioneins in order to reduce toxicity, and R.philippinarum increased glutathione S-transferase Ω activity, that catalyzes monomethyl arsenate reduction, the rate-limiting reaction in arsenic biotransformation. When exposed to Hg, R. decussatus presented, higher synthesis of antioxidant enzymes and lower LPO, being able to better tolerate Hg than the exotic species R. philippinarum. Thus under relevant levels of As and Hg contamination our work evidenced the higher ability of R. decussatus to survive and inhabit coastal environments not heavily contaminated by Hg and As. Copyright © 2015 Elsevier Inc. All rights reserved.

Bioaccessibility of Hg, Cd and As in cooked black scabbard fish and edible crab.

Science.gov (United States)

Maulvault, Ana Luísa; Machado, Raquel; Afonso, Cláudia; Lourenço, Helena Maria; Nunes, Maria Leonor; Coelho, Inês; Langerholc, Tomaz; Marques, António

2011-11-01

Regular consumption of seafood has been widely recommended by authorities. Yet, some species accumulate high levels of contaminants like Hg, Cd and As. In addition, the risks associated to the consumption of such seafood may increase if consumers use cooking practices that enhance the concentration of contaminants and their bioaccessibility. In this study, the bioaccessibility of Hg, Cd and As was assessed with in vitro human digestion of raw and cooked black scabbard fish (Hg; steamed, fried and grilled) and edible crab (Cd and As; steamed and boiled) tissues. Additionally, the toxicological hazards associated with the consumption of these products were also discussed. Generally, Hg, Cd and As bioacessibility increased throughout the digestion process. Cadmium and As revealed high bioaccessibility rates in raw and cooked samples (up to 100%), whereas lower bioaccessible fractions of Hg was observed (up to 40%). Furthermore, this study pointed out the importance of food matrix, elemental chemical properties and cooking practices in the bioaccessibility of Hg, Cd and As. The toxicological hazards revealed that edible crab brown meat (Cd) and grilled black scabbard fish (MeHg) consumption in children should be moderated. In contrast, edible crab muscle (Cd) and fried or steamed black scabbard fish (MeHg) should be consumed to minimize exposure. The use of bioaccessible contaminant data strongly reduced the toxicological risks of MeHg, whereas less risk reduction occurred with Cd and inorganic As. Copyright © 2011 Elsevier Ltd. All rights reserved.

Long-distance transport of Hg, Sb, and As from a mined area, conversion of Hg to methyl-Hg, and uptake of Hg by fish on the Tiber River basin, west-central Italy

Science.gov (United States)

Gray, John E.; Rimondi, Valentina; Costagliola, Pilario; Vaselli, Orlando; Lattanzi, Pierfranco

2014-01-01

Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (water varied from 1.2 to 320 ng/L, all of which were below the 1,000 ng/L Italian drinking water Hg guideline and the 770 ng/L U.S. Environmental Protection Agency (USEPA) guideline recommended to protect against chronic effects to aquatic wildlife. Methyl-Hg concentrations in stream water varied from water samples contained concentrations of As (drinking water guidelines to protect human health (10 μg/L for As and 20 μg/L for Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.

Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance.

Science.gov (United States)

Cruz, Kimberly; Guézennec, Jean; Barkay, Tamar

2017-07-01

Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg uptake capacities ranged from 0.005 to 0.454 mmol Hg/g for the different EPS. To determine if EPS production could alter bacterial Hg tolerance, Escherichia coli K-12 strains and their EPS defective mutants were tested by the disc inhibition assay. Mercury inhibited growth in a dose-dependent manner with wild-type strains having smaller (~1 mm), but statistically significant, zones of inhibition than various mutants and this difference was related to a 2-fold decline in the amount of EPS produced by the mutants relative to cell biomass. These experiments identified colanic acid and hexosamine as Hg-binding moieties in EPS. Together these data indicate that binding of Hg to EPS affords a low level of resistance to the producing bacteria.

Observation of Hg-diffusion in CdTe using heavy ion (40MeV-O5+) backscattering

International Nuclear Information System (INIS)

Otake, H.; Takita, K.; Murakami, K.; Masuda, K.; Kudo, H.; Seki, S.

1984-01-01

Diffusion of Hg in the near-surface region of CdTe crystals was observed by means of 40MeV-O 5+ ion backscattering. CdTe crystals immersed in Hg were kept in furnace at 280 -- 340 0 C for 2 -- 240hours. The backscattering spectra of these crystals were measured. The concentration of the diffused Hg atoms in the surface reached to 4 x 10 20 cm -3 , and Hg distribution was observed up to 1.4 μm from surface. Temperature dependence of the diffusion coefficients was determined as D = 5 x 10 3 exp (-2.0 +- 0.3eV/kT) cm 2 /sec. Hg-diffusion was not observed in the case of CdTe kept in Hg with a small amount of Cd. These facts suggest that Hg diffusion is controlled by the diffusion of Cd-vacancy. A method of observing the Hg-atoms profile in the near-surface region of the semiconductor was established. (author)

Accumulation of Methylmercury in Invertebrates and Masked Shrews (Sorex cinereus) at an Upland Forest-Peatland Interface in Northern Minnesota, USA.

Science.gov (United States)

Tavshunsky, Ilana; Eggert, Susan L; Mitchell, Carl P J

2017-12-01

Mercury (Hg) methylation is often elevated at the terrestrial-peatland interface, but methylmercury (MeHg) production at this "hot spot" has not been linked with in situ biotic accumulation. We examined total Hg and MeHg levels in peat, invertebrates and tissues of the insectivore Sorex cinereus (masked shrew), inhabiting a terrestrial-peatland ecotone in northern Minnesota, USA. Mean MeHg concentrations in S. cinereus (71 ng g -1 ) fell between concentrations measured in spiders (mean 70-140 ng g -1 ), and ground beetles and millipedes (mean 29-42 ng g -1 ). Methylmercury concentrations in S. cinereus increased with age and differed among tissues, with highest concentrations in kidneys and muscle, followed by liver and brain. Nearly all Hg in S. cinereus was in the methylated form. Overall, the high proportional accumulation of MeHg in peat at the site (3.5% total Hg as MeHg) did not lead to particularly elevated concentrations in invertebrates or shrews, which are below values considered a toxicological risk.

Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web

Energy Technology Data Exchange (ETDEWEB)

Pickhardt, Paul C. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States)]. E-mail: paul.pickhardt@stonybrook.edu; Folt, Carol L. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States); Chen, Celia Y. [Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 (United States); Klaue, Bjoern [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Blum, Joel D. [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

2005-03-01

There is a well documented accumulation of mercury in fish to concentrations of concern for human consumption. Variation in fish Hg burden between lakes is often high and may result from differences in Hg transfer through lower levels of the food web where mercury is bioconcentrated to phytoplankton and transferred to herbivorous zooplankton. Prior research derived patterns of mercury accumulation in freshwater invertebrates from field collected animals. This study provides results from controlled mesocosm experiments comparing the effects of zooplankton composition, algal abundance, and the chemical speciation of mercury on the ability of zooplankton to accumulate mercury from phytoplankton and transfer that mercury to planktivores. Experiments were conducted in 550-L mesocosms across a gradient of algal densities manipulated by inorganic nutrient additions. Enriched, stable isotopes of organic (CH{sub 3} {sup 200}HgCl) and inorganic ({sup 201}HgCl{sub 2}) mercury were added to mesocosms and their concentrations measured in water, seston, and three common zooplankton species. After 2 weeks, monomethylmercury (MMHg) concentrations were two to three times lower in the two copepod species, Leptodiaptomus minutus and Mesocyclops edax than in the cladoceran, Daphnia mendotae. All three zooplankton species had higher MMHg concentrations in mesocosms with low versus high initial algal abundance. However, despite higher concentrations of inorganic mercury (Hg{sub I}) in seston from low nutrient mesocosms, there were no significant differences in the Hg{sub I} accumulated by zooplankton across nutrient treatments. Bioaccumulation factors for MMHg in the plankton were similar to those calculated for plankton in natural lakes and a four-compartment (aqueous, seston, macrozooplankton, and periphyton/sediments) mass balance model after 21 days accounted for {approx}18% of the CH{sub 3} {sup 200}Hg and {approx}33% of the {sup 201}Hg added. Results from our experiments

Impacts of zooplankton composition and algal enrichment on the accumulation of mercury in an experimental freshwater food web

International Nuclear Information System (INIS)

Pickhardt, Paul C.; Folt, Carol L.; Chen, Celia Y.; Klaue, Bjoern; Blum, Joel D.

2005-01-01

There is a well documented accumulation of mercury in fish to concentrations of concern for human consumption. Variation in fish Hg burden between lakes is often high and may result from differences in Hg transfer through lower levels of the food web where mercury is bioconcentrated to phytoplankton and transferred to herbivorous zooplankton. Prior research derived patterns of mercury accumulation in freshwater invertebrates from field collected animals. This study provides results from controlled mesocosm experiments comparing the effects of zooplankton composition, algal abundance, and the chemical speciation of mercury on the ability of zooplankton to accumulate mercury from phytoplankton and transfer that mercury to planktivores. Experiments were conducted in 550-L mesocosms across a gradient of algal densities manipulated by inorganic nutrient additions. Enriched, stable isotopes of organic (CH 3 200 HgCl) and inorganic ( 201 HgCl 2 ) mercury were added to mesocosms and their concentrations measured in water, seston, and three common zooplankton species. After 2 weeks, monomethylmercury (MMHg) concentrations were two to three times lower in the two copepod species, Leptodiaptomus minutus and Mesocyclops edax than in the cladoceran, Daphnia mendotae. All three zooplankton species had higher MMHg concentrations in mesocosms with low versus high initial algal abundance. However, despite higher concentrations of inorganic mercury (Hg I ) in seston from low nutrient mesocosms, there were no significant differences in the Hg I accumulated by zooplankton across nutrient treatments. Bioaccumulation factors for MMHg in the plankton were similar to those calculated for plankton in natural lakes and a four-compartment (aqueous, seston, macrozooplankton, and periphyton/sediments) mass balance model after 21 days accounted for ∼18% of the CH 3 200 Hg and ∼33% of the 201 Hg added. Results from our experiments corroborate results from field studies and suggest the

A water-soluble and retrievable ruthenium-based probe for colorimetric recognition of Hg(II) and Cys.

Science.gov (United States)

Cui, Yali; Hao, Yuanqiang; Zhang, Yintang; Liu, Baoxia; Zhu, Xu; Qu, Peng; Li, Deliang; Xu, Maotian

2016-08-05

A new ruthenium-based complex 1 [(bis(4,4'-dimethylphosphonic-2,2'-bipyridine) dithiocyanato ruthenium (II))] was developed as a colorimetric probe for the detection of Hg(II) and Cys (Cysteine). The obtained compound 1 can give interconversional color changes upon the alternating addition of Hg(II) and Cys in 100% aqueous solution. The specific coordination between NCS groups with Hg(II) can lead to the formation of 1-Hg(2+) complex, which can induce a remarkable spectral changes of probe 1. Afterwards the formed 1-Hg(2+) complex can act as effective colorimetric sensor for Cys. Owing to the stronger binding affinity of sulfhydryl group to Hg(2+), Cys can extract Hg(2+) from 1-Hg(2+) complex resulting in the release of 1 and the revival of absorption profile of the probe 1. By introducing the hydrophilic phosphonic acid groups, the proposed probe exhibited excellent water solubility. The limits of detection (LODs) of the assay for Hg(2+) and Cys are calculated to be 15nM and 200nM, respectively. Copyright © 2016. Published by Elsevier B.V.

A Neutron Scattering Study of Lattice Dynamics of HgTe and HgSe

DEFF Research Database (Denmark)

Kepa, H.; Giebultowicz, T.; Buras, B.

1982-01-01

The dispersion relations for the acoustic and optic phonons in HgTe and for the acoustic phonons in HgSe were determined by neutron inelastic scattering in three high symmetry directions. The effect of the free-carrier screening of the long-range electric field of LO phonons in HgTe was observed....... The formalism of the rigid ion model is used for numerical calculations of the phonon dispersion relations and the phonon densities of states in HgTe and HgSe....

Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

Energy Technology Data Exchange (ETDEWEB)

Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

2016-06-28

Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

Different transport mechanisms for cadmium and mercury in Caco-2 cells: inhibition of Cd uptake by Hg without evidence for reciprocal effects

International Nuclear Information System (INIS)

Aduayom, Ismaeel; Campbell, Peter G.C.; Denizeau, Francine; Jumarie, Catherine

2003-01-01

Cadmium/Hg interactions have been studied in the TC7 clone of the enterocytic-like Caco-2 cells to test the hypothesis that these metals may compete for intestinal transport. Comparison of the kinetic parameter values for 203 Hg(II) and 109 Cd(II) uptake in a serum-free medium revealed that Hg is accumulated much more rapidly and to higher concentrations. The very rapid uptake/binding step and the initial uptake rate of 109 Cd were both significantly inhibited by an excess of unlabeled Cd or Hg (apparent K i for Hg of 9.3 ± 1.2 μM) without reciprocal effects. 109 Cadmium uptake was highly sensitive to temperature and a significant fraction of accumulation (12%) was EDTA extractable. 203 Hg uptake remained insensitive to temperature or the EDTA washing procedure. However, the uptake of both tracers was half-decreased when an excess of the respective unlabeled metal was added in the stop solution, suggesting an exchange mechanism for adsorption. Cell pretreatment with N-ethylmaleimide (NEM) led to a 30% decrease or a 73% increase in the 3-min specific transport of 109 Cd when NEM was still present in or removed from the uptake medium, respectively. NEM had no effect on 203 Hg uptake. Overall our results suggest the involvement of a saturable specific mechanism for Cd, which is highly sensitive to inhibition by Hg and NEM under some conditions, and a nonspecific passive diffusion for Hg. The Hg- or NEM-induced inhibition of Cd uptake likely involves a thiol-mediated reaction, but our results suggest that NEM pretreatment may activate other cellular mechanisms leading to a stimulatory effect

Atmospheric mercury accumulation between 5900 and 800 calibrated years BP in the high arctic of Canada recorded by Peat Hummocks

DEFF Research Database (Denmark)

Givelet, N.; Roos-Barraclough, F.; Goodsite, Michael Evan

2004-01-01

In this paper, we present the first comprehensive long-term record of preanthropogenic rates of atmospheric mercury accumulation in dated peat deposits for the High Arctic of Canada. Geochemical studies of two peat hummocks from Bathurst Island, Nunavut reveal substantial inputs from soil dust...... (titanium), marine aerosols (bromine), and mineral-water interactions (uranium). Mercury, however, was supplied to these peat mounds exclusively by atmospheric deposition. Mercury concentration measurements and age dating of the peat profiles indicate rather constant natural "background" mercury flux of ca....... 1 microgram per square meter per year from 5900 to 800 calibrated years BP. These values are well within the range of the mercury fluxes reported from other Arctic locations, but also by peat cores from southern Canada that provide a record of atmospheric Hg accumulation extending back 8000 years...

Electron beam induced Hg desorption and the electronic structure of the Hg depleted surface of Hg1/sub -//sub x/Cd/sub x/Te

International Nuclear Information System (INIS)

Shih, C.K.; Friedman, D.J.; Bertness, K.A.; Lindau, I.; Spicer, W.E.; Wilson, J.A.

1986-01-01

Auger electron spectroscopy (AES), x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and angle-resolved ultraviolet photoemission spectroscopy (ARPES) were used to study the electron beam induced Hg desorption from a cleaved (110)Hg/sub 1-//sub x/Cd/sub x/Te surface and the electronic structure of the Hg depleted surface. Solid state recrystallized Hg/sub 1-//sub x/Cd/sub x/Te single crystals were used. It was found that the electron beam heating dominated the electron beam induced Hg desorption on Hg/sub 1-//sub x/Cd/sub x/Te. At the electron beam energy used, the electron beam heating extended several thousand angstroms deep. However, the Hg depletion saturated after a few monolayers were depleted of Hg atoms. At the initial stage of Hg loss (only 3%), the surface band bends upward (more p type). The ARPES spectrum showed the loss of some E vs k dispersion after 22% Hg atoms were removed from the surface region, and no dispersion was observed after 43% Hg atoms were removed. These results have important implications on the electronic structure of the surfaces and interfaces of which the stoichiometry is altered

Superconductivity of Hg3NbF6 and Hg3TaF6

International Nuclear Information System (INIS)

Datars, W.R.; Morgan, K.R.; Gillespie, R.J.

1983-01-01

Low-temperature ac susceptibility measurements show that two new metallic compounds, Hg 3 TaF 6 and Hg 3 NbF 6 , are superconductors with a critical temperature of 7.0 K. Critical fields are 20% higher in Hg 3 TaF 6 but the temperature dependence of the critical field of the compounds is very similar down to 1.35 K. The critical field extrapolated to T = 0 K is 0.17 T for Hg 3 TaF 6 and 0.13 T for Hg 3 NbF 6

Accumulation, sources and health risks of trace metals in elevated geochemical background soils used for greenhouse vegetable production in southwestern China.

Science.gov (United States)

Zhang, Haidong; Huang, Biao; Dong, Linlin; Hu, Wenyou; Akhtar, Mohammad Saleem; Qu, Mingkai

2017-03-01

Greenhouse vegetable cultivation with substantive manure and fertilizer input on soils with an elevated geochemical background can accumulate trace metals in soils and plants leading to human health risks. Studies on trace metal accumulation over a land use shift duration in an elevated geochemical background scenario are lacking. Accumulation characteristics of seven trace metals in greenhouse soil and edible plants were evaluated along with an assessment of the health risk to the consumers. A total of 118 greenhouse surface soils (0-20cm) and 30 vegetables were collected from Kunming City, Yunnan Province, southwestern China, and analyzed for total Cd, Pb, Cu, Zn, As, Hg, and Cr content by ICP-MS and AFS. The trace metals were ordered Cu>Cd>Hg>Zn>Pb>As>Cr in greenhouse soils accumulation level, and the geo-accumulation index suggested the soil more severely polluted with Cd, Cu, Hg and Zn. The greenhouse and open-field soils had significant difference in Cd, Cr and Zn. The duration of shift from paddy to greenhouse land-use significantly influenced trace metal accumulation with a dramatic change during five to ten year greenhouse land-use, and continuous increase of Cd and Hg. A spatial pattern from north to south for Cd and Hg and a zonal pattern for Cu and Zn were found. An anthropogenic source primarily caused trace metal accumulation, where the principal component analysis/multiple linear regression indicated a contribution 61.2%. While the assessment showed no potential risk for children and adults, the hazard health risks index was greater than one for adolescents. The extended duration of land use as greenhouses caused the trace metal accumulation, rotation in land use should be promoted to reduce the health risks. Copyright © 2016. Published by Elsevier Inc.

Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste

Energy Technology Data Exchange (ETDEWEB)

Johnson, Bryce E., E-mail: bjohnson@ce.berkeley.edu [Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Esser, Bradley K. [Chemical Sciences Division, 7000 East Avenue, Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Whyte, Dyan C.; Ganguli, Priya M.; Austin, Carrie M. [California Regional Water Quality Control Board, 1515 Clay St., Suite 1400, Oakland, CA 94612 (United States); Hunt, James R. [Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

2009-09-01

The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta's sediment surface had MMHg concentrations ranging from 7.5 to 31.5 ng/g, and the top 1 cm of sediment directly under the mats had two times greater MMHg concentrations compared to adjacent locations without algal covering. Spatial trends in resident biota reflect enhanced MMHg uptake at the delta compared to other bay locations. Eighteen sediment cores, 1 to 2 m deep, collected from the 1.2 km{sup 2} delta provide an estimate of a total mercury (Hg) inventory of 2500 {+-} 500 kg. Sediment Hg concentrations ranged from pre-mining background conditions of approximately 0.1 {mu}g/g to a post-mining maximum of 5 {mu}g/g. Sediment accumulation rates were determined from three sediment cores using measured differences of {sup 137}Cs activity. We estimate a pre-mining Hg accumulation of less than 20 kg/yr, and a period of maximum Hg accumulation in the 1970s and 1980s with loading rates greater than 50 kg/yr, corresponding to the failure of a tailings dam at the mine site. At the time of sampling (2003) over 40 kg/yr of Hg was still accumulating at the delta, indicating limited recovery. We attribute observed spatial evolution of elevated Hg levels to ongoing inputs and sediment re-working, and estimate the inventory of the anthropogenic fraction of total Hg to be at least 1500 {+-} 300 kg. We suggest ongoing sediment inputs and methylation at the deltaic surface support enhanced mercury levels for resident biota and transfer to higher trophic levels throughout the Bay.

40 CFR 60.4112 - Changing Hg designated representative and alternate Hg designated representative; changes in...

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Changing Hg designated representative and alternate Hg designated representative; changes in owners and operators. 60.4112 Section 60.4112... Generating Units Hg Designated Representative for Hg Budget Sources § 60.4112 Changing Hg designated...

Assessment of micro, macro, toxic elements (Cd, Hg, Pb) and fatty acids profile in consumed fish commercially available in Cananeia and Cubatao, Sao Paulo State; Avaliacao de micro e macroelementos, elementos toxicos (Cd, Hg e Pb) e acidos graxos, em peixes disponiveis comercialmente para consumo em Cananeia e Cubatao, Estado de Sao Paulo

Energy Technology Data Exchange (ETDEWEB)

Curcho, Michel Rodrigues da Silva Morales

2009-07-01

Aside from their nutritional importance, fish are considered one of the most important bio indicators in aquatic systems for the estimation of pollution levels by toxic metals. This is so, since fish can bio accumulate these elements and they occupy different trophic levels and present different sizes and age. The purpose of the present study was to contribute with important data for the knowledge of nutritional and toxic constituents in muscles of the most consumed fish species from two coastal regions, Cananeia and Cubatao. Cananeia fish species analyzed were: Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Centropomus undecimalis (Robalo peba) and Mugil platanus (Tainha). From Cubatao, Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Menticirrhus americanus (Perna de moca), Sardella braziliensis (Sardinha) and Mugil liza (Tainha). For this study, analytical methodologies were developed and validated, regarding precision and accuracy, by means of certified reference materials. Micronutrients (Ca, Fe, K, Na, Se and Zn) and some trace elements (As, Br, Co, Cr, Rb) in fish muscle were determined by means of neutron activation analysis (NAA). Cold Vapor Atomic Absorption Spectrometry (CV AAS) was used for total Hg determination and Electrothermal Atomic Absorption Spectrometry (ET AAS) for Cd and Pb determinations. Proximate composition determinations according to AOAC methodologies and fatty acids profiles by gas chromatography were done in these muscle fish samples. Regarding fatty acids profile from the {omega}-6 family, Tainha species pool presented the highest values (8.9%) and Pescada species pool the lowest ones (4.4%) for Cananeia species. Fatty acids from the {omega}-3 family, Sardinha pool species presented the highest values (31.8%) for all species analyzed. Regarding micronutrients content great concentration variations between individual of the same species and between different species were observed. Discriminate analysis

Pathways of CH3Hg and Hg ingestion in benthic organisms: an enriched isotope approach.

Science.gov (United States)

Taylor, Vivien F; Bugge, Deenie; Jackson, Brian P; Chen, Celia Y

2014-05-06

Mercury is a widespread contaminant in marine food webs, and identifying uptake pathways of mercury species, CH3Hg(+) and Hg(2+), into low trophic level organisms is important to understanding its entry into marine food webs. Enriched stable isotope tracers were used to study benthic vs. pelagic pathways of CH3Hg(+) and Hg(2+) uptake via food to the infaunal estuarine amphipod, Leptocheirus plumulosus. Algal cells differentially labeled with isotopically enriched CH3Hg(+) or Hg(2+) were added simultaneously to the sediment and water column of microcosms, and Hg species were monitored in amphipods and in sediment and water compartments. Methylation of Hg(2+) occurred during the course of the experiment, enhancing the uptake of Hg(2+) spikes. Trophic transfer of Hg from algae added to the water column was determined to be the major uptake route for amphipods, suggesting inputs of contaminated organic matter from the pelagic zone are important to mercury bioaccumulation even in organisms living in sediments.

Elastic, dynamical, and electronic properties of LiHg and Li3Hg: First-principles study

Science.gov (United States)

Wang, Yan; Hao, Chun-Mei; Huang, Hong-Mei; Li, Yan-Ling

2018-04-01

The elastic, dynamical, and electronic properties of cubic LiHg and Li3Hg were investigated based on first-principles methods. The elastic constants and phonon spectral calculations confirmed the mechanical and dynamical stability of the materials at ambient conditions. The obtained elastic moduli of LiHg are slightly larger than those of Li3Hg. Both LiHg and Li3Hg are ductile materials with strong shear anisotropy as metals with mixed ionic, covalent, and metallic interactions. The calculated Debye temperatures are 223.5 K and 230.6 K for LiHg and Li3Hg, respectively. The calculated phonon frequency of the T2 g mode in Li3Hg is 326.8 cm-1. The p states from the Hg and Li atoms dominate the electronic structure near the Fermi level. These findings may inspire further experimental and theoretical study on the potential technical and engineering applications of similar alkali metal-based intermetallic compounds.

Phytoremediation of Pb and Hg by using Scirpus mucronatus with addition of bacterial inoculums

International Nuclear Information System (INIS)

Hamzah, A.; Yatim, N.I.; Sarmani, S.B.

2015-01-01

Two heavy metal-resistant rhizobacteria bacteria (Brevundimonas diminuta SF-S1-5 and Alcaligenes faecalis SF-S1-60) were bioaugmented in sand and also spiked with 100 ppm Pb and 1 ppm Hg and the removal of these metals was monitored using plant, Scirpus mucronatus. The highest accumulation of Pb and Hg were obtained in the root of S. mucronatus inoculated with A. faecalis at day 42 and 28, respectively. Plant inoculated with A. faecalis also showed the highest bioaccumulation coefficient and bioconcentration factor values > 1 compared to plant inoculated with B. diminuta and control. (author)

Metallothionein expression in chloroplasts enhances mercury accumulation and phytoremediation capability.

Science.gov (United States)

Ruiz, Oscar N; Alvarez, Derry; Torres, Cesar; Roman, Laura; Daniell, Henry

2011-06-01

Genetic engineering to enhance mercury phytoremediation has been accomplished by expression of the merAB genes that protects the cell by converting Hg[II] into Hg[0] which volatilizes from the cell. A drawback of this approach is that toxic Hg is released back into the environment. A better phytoremediation strategy would be to accumulate mercury inside plants for subsequent retrieval. We report here the development of a transplastomic approach to express the mouse metallothionein gene (mt1) and accumulate mercury in high concentrations within plant cells. Real-time PCR analysis showed that up to 1284 copies of the mt1 gene were found per cell when compared with 1326 copies of the 16S rrn gene, thereby attaining homoplasmy. Past studies in chloroplast transformation used qualitative Southern blots to evaluate indirectly transgene copy number, whereas we used real-time PCR for the first time to establish homoplasmy and estimate transgene copy number and transcript levels. The mt1 transcript levels were very high with 183,000 copies per ng of RNA or 41% the abundance of the 16S rrn transcripts. The transplastomic lines were resistant up to 20 μm mercury and maintained high chlorophyll content and biomass. Although the transgenic plants accumulated high concentrations of mercury in all tissues, leaves accumulated up to 106 ng, indicating active phytoremediation and translocation of mercury. Such accumulation of mercury in plant tissues facilitates proper disposal or recycling. This study reports, for the first time, the use of metallothioneins in plants for mercury phytoremediation. Chloroplast genetic engineering approach is useful to express metal-scavenging proteins for phytoremediation. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

Impacts of crab bioturbation and local pollution on sulfate reduction, Hg distribution and methylation in mangrove sediments, Rio de Janeiro, Brazil.

Science.gov (United States)

Correia, Raquel Rose Silva; Guimarães, Jean Remy Davée

2016-08-15

Mercury (Hg) and methylmercury (MeHg) are highly toxic and poorly studied in mangroves. Burrowing Uca crabs change sediment topography and biogeochemistry and thus may affect Hg distribution and MeHg formation. We studied added (203)Hg distribution, Me(203)Hg formation and sulfate reduction rates (SRR) in sediment aquariums containing Uca leptodactyla; and analyzed profiles of Me(203)Hg formation and SRR in sediment cores from two mangroves with distinct environmental impacts. MeHg formation and SRR were higher in the top (≤6cm) sediment and there was no significant difference in Hg methylation in more or less impacted mangroves. In aquariums, crab bioturbation favored Hg retention in the sediment. In the treatment without crabs, Hg volatilization and water Hg concentrations were higher. Hg methylation was higher in bioturbated aquariums but SRR were similar in both treatments. These findings suggest that bioturbating activity favors Hg retention in sediment but also promotes MeHg formation near the surface. Copyright © 2016 Elsevier Ltd. All rights reserved.

Triaxiality in the even-mass Hg isotopes: A discontinuity at 200Hg

International Nuclear Information System (INIS)

Morrison, I.; Spear, R.H.

1981-01-01

The mass dependence of excitation energies of the 2 + 1 , 2 + 2 , and 4 + 1 states of the even-mass Hg isotopes, and of some related B(E2) values, shows a marked discontinuity at 200 Hg. Analysis of B(E2;0 + 1 →2 + 1 ) values in terms of an extended interacting boson approximation model suggests that this discontinuity is due to a change in the proton and neutron distributions at 200 Hg. Apart from 200 Hg, the data favor γ-soft models rather than the rigid triaxial-rotor model

On the mean square displacements (MSD) of Hg and Te in HgTe

International Nuclear Information System (INIS)

Madhavan, Y.; Ramachandran, K.

1989-01-01

The mean square displacements (MSD) of Hg and Te in the perfect system of HgTe are worked out in the modified rigid ion model of Plumelle and Vandevyver. Also the MSD of Hg and Te neighbours around anion and cation vacancies in HgTe are worked out giving an active role for the vacancy following the theory of Maradudin et al. The results are compared with experimental values. (author)

Exploring the Hg pollution in global marginal seas by trophic biomagnification in demersal fishes

Science.gov (United States)

Tseng, C. M.; Hsieh, Y. C.; Chiang, C. Y.; Lamborg, C. H.; Chang, N. N.; Shiao, J. C.

2017-12-01

Limited knowledge still exists concerning the effects of size composition and trophic level (TL) on mercury levels in the demersal fishes associated with human activities in the marginal seas. In this study, we found evidence of strong control of TL on the Hg in fish and its biomagnification via food webs in the ECS. Total Hg in seven selected fish species, collected during the cruise OR1- 890 in July 2009, ranged from 2.6 and 256.2 ng g-1 (n=72). There were good linear relationships between Hg concentrations and fish body length (R2 = 0.79) and weight (R2 = 0.82), respectively, other than environmental variables (R2 = 0 0.03). It indicates that the Hg concentration in fish is mainly controlled by the growth mechanism of the fish itself through food chain transfer. In order to investigate how Hg levels in fish through trophic magnification associated with environmental changes, we hence developed the empirical method to calculate Hg accumulation rate (MAR) via the relationship of Hg concentration with the fish age for each fish species. The results further showed a significantly positive correlation of MAR with trophic levels, which relationship is Ln MAR =6.1 TL-15.8 (R2 = 0.89) in the ECS shelf. The magnitude of the slope (δMAR/δTL) as a biomagnification index of demersal fish shall provide the feasibility to compare Hg pollution situation among different marine ecosystems. Globally, the biomagnification indicator in the demersal fishes of the ECS is much greater than those in other marginal seas, suggesting high regional Hg pollution impacts from Mainland China.

Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.

Science.gov (United States)

Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

2014-01-01

We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements.

Capability of selected crop plants for shoot mercury accumulation from polluted soils: phytoremediation perspectives.

Science.gov (United States)

Rodriguez, Luis; Rincón, Jesusa; Asencio, Isaac; Rodríguez-Castellanos, Laura

2007-01-01

High-biomass crops can be considered as an alternative to hyperaccumulator plants to phytoremediate soils contaminated by heavy metals. In order to assess their practical capability for the absorption and accumulation of Hg in shoots, barley, white lupine, lentil, and chickpea were tested in pot experiments using several growth substrates. In the first experimental series, plants were grown in a mixture of vermiculite and perlite spiked with 8.35 microg g(-1) d.w. of soluble Hg. The mercury concentration of the plants' aerial tissues ranged from 1.51 to 5.13 microg g(-1) d.w. with lentil and lupine showing the highest values. In a second experiment carried out using a Hg-polluted soil (32.16 microg g(-1) d.w.) collected from a historical mining area (Almadén, Spain), the crop plants tested only reached shoot Hg concentration up to 1.13 microg g(-1) d.w. In the third experimental series, the Almadén soil was spiked with 1 microg g(-1) d.w. of soluble Hg; as a result, mercury concentrations in the plant shoots increased approximately 6 times for lupine, 5 times for chickpea, and 3.5 times for barley and lentil, with respect to those obtained with the original soil without Hg added. This marked difference was attributed to the low availability of Hg in the original Almadin soil and its subsequent increase in the Hg-spiked soil. The low mercury accumulation yields obtained for all plants do not make a successful decontamination of the Almadén soils possible byphytoremediation using crop plants. However, since the crops tested can effectively decrease the plant-available Hg level in this soil, their use could, to some extent, reduce the environmental risk of Hg pollution in the area.

Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

International Nuclear Information System (INIS)

Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-Di Pasquale, M.; Grenier, J.L.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

2012-01-01

San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

Energy Technology Data Exchange (ETDEWEB)

Davis, J.A., E-mail: jay@sfei.org [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Looker, R.E. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); Yee, D. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Marvin-Di Pasquale, M. [U.S. Geological Survey, Water Resources Division/MS 480, 345 Middlefield Road, Menlo Park, CA 94025 (United States); Grenier, J.L. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Austin, C.M. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); McKee, L.J.; Greenfield, B.K. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Brodberg, R. [California Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1001 I Street, Sacramento, CA 95812 (United States); Blum, J.D. [Department of Geological Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, MI 48109 (United States)

2012-11-15

San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

Magnetic fields of HgMn stars

DEFF Research Database (Denmark)

Hubrig, S.; González, J. F.; Ilyin, I.

2012-01-01

Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... failed to detect magnetic fields, indicating an upper limit on the longitudinal field between 8 and 15G. In these LSD studies, assumptions were made that all spectral lines are identical in shape and can be described by a scaled mean profile. Aims. We re-analyse the available spectropolarimetric material...

Hyperemesis Gravidarum (HG)

Science.gov (United States)

... Treatments Risks Complications Impact Take a Poll If HG continued past mid-pregnancy , did you experience complications ... Understanding Hyperemesis | Overview About Hyperemesis Gravidarum Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting ...

Photoionization study of HgAr

International Nuclear Information System (INIS)

Linn, S.H.; Brom, J.M. Jr.; Tzeng, W.; Ng, C.Y.

1985-01-01

Photoionization efficiency data for HgAr + have been obtained in the region of 680--1240 A. The ionization energy of HgAr was determined to be 10.217 +- 0.012 eV. This value allows the calculation of the dissociation energy of HgAr + to be 0.228 +- 0.017 eV. The relative probabilities for the formation of HgAr + via the reactions Ar* x Hg or Hg* x Ar→ HgAr + +e - with Ar* and Hg* prepared in high Rydberg states in the energy range of 10.22--15.79 eV were estimated. Although the radii for the 3d and 5s Rydberg ortitals of Ar have similar values, the probabilities for the formation of HgAr + from Hg x Ar* with Ar* in the 5s[3/2] 0 1 and 5s'[1/2] 0 1 Rydberg states are substantially greater than those when the Ar* excited atoms are in the 3d[1/2] 0 1 , 3s[3/2] 0 1 , and 3d'[3/2] 0 1 Rydberg levels. The ratio for the cross sections for the formation of HgAr + from Hg x Ar* with Ar* formed in the 3d[1/2] 0 1 and 4d[1/2] 0 1 states, as well as that with Ar* prepared in the 5d[1/2] 0 1 and 6d[1/2] 0 1 states, were found to be consistent with the predictions of the previous impact parameter calculations

The influence of Parachlorella beyerinckii CK-5 on the absorption and excretion of methylmercury (MeHg) in mice.

Science.gov (United States)

Uchikawa, Takuya; Yasutake, Akira; Kumamoto, Yoshimitsu; Maruyama, Isao; Kumamoto, Shoichiro; Ando, Yotaro

2010-02-01

Chlorella (Parachlorella beyerinckii CK-5), previously identified as Chlorella vulgaris CK-5, is a unicellular green algae that has for many years been used as a nutritional supplement. In order to investigate the effects of methylmercury (MeHg) detoxification by Chlorella, we examined the absorption and excretion of MeHg in mice. Female C57BL/6N mice were randomly divided into three groups of five, and were housed in metabolism cages. Mice were orally administered MeHg chloride at doses of 5 mg (4 mg Hg)/kg body weight with or without 100 mg/mouse of P. beyerinckii powder (BP), and were assigned to either a MeHg group or MeHg + BP group, accordingly. Twenty-four hr after oral administration, feces and urine were collected, and blood, liver, and kidney samples were obtained. Total mercury contents in the samples obtained were determined using an atomic absorption method. The amounts of Hg excreted in feces and urine of the MeHg + BP group were increased nearly 1.9 and 2.2-fold compared with those of the MeHg group. On the other hand, blood and organ Hg levels were not significantly different between two groups. These results suggest that the intake of BP may induce the excretion of Hg both in feces and urine, although it does not affect MeHg absorption from the gastrointestinal tract. The effect of BP on the tissue mercury accumulation may become evident in a long-term experiment.

Impacts of Activated Carbon Amendment on Hg Methylation, Demethylation and Microbial Activity in Marsh Soils

Science.gov (United States)

Gilmour, C. C.; Ghosh, U.; Santillan, E. F. U.; Soren, A.; Bell, J. T.; Butera, D.; McBurney, A. W.; Brown, S.; Henry, E.; Vlassopoulos, D.

2015-12-01

In-situ sorbent amendments are a low-impact approach for remediation of contaminants in sediments, particular in habitats like wetlands that provide important ecosystem services. Laboratory microcosm trials (Gilmour et al. 2013) and early field trials show that activated carbon (AC) can effectively increase partitioning of both inorganic Hg and methylmercury to the solid phase. Sediment-water partitioning can serve as a proxy for Hg and MeHg bioavailability in soils. One consideration in using AC in remediation is its potential impact on organisms. For mercury, a critical consideration is the potential impact on net MeHg accumulation and bioavailability. In this study, we specifically evaluated the impact of AC on rates of methylmercury production and degradation, and on overall microbial activity, in 4 different Hg-contaminated salt marsh soils. The study was done over 28 days in anaerobic, sulfate-reducing slurries. A double label of enriched mercury isotopes (Me199Hg and inorganic 201Hg) was used to separately follow de novo Me201Hg production and Me199Hg degradation. AC amendments decreased both methylation and demethylation rate constants relative to un-amended controls, but the impact on demethylation was stronger. The addition of 5% (dry weight) regenerated AC to soil slurries drove demethylation rate constants to nearly zero; i.e. MeHg sorption to AC almost totally blocked its degradation. The net impact was increased solid phase MeHg concentrations in some of the soil slurries with the highest methylation rate constants. However, the net impact of AC amendments was to increase MeHg (and inorganic Hg) partitioning to the soil phase and decrease concentrations in the aqueous phase. AC significantly decreased aqueous phase inorganic Hg and MeHg concentrations after 28 days. Overall, the efficacy of AC in reducing aqueous MeHg was highest in the soils with the highest MeHg concentrations. The AC addition did not significantly impact microbial activity, as

Centennial record of anthropogenic impacts in Galveston Bay: Evidence from trace metals (Hg, Pb, Ni, Zn) and lignin oxidation products.

Science.gov (United States)

Al Mukaimi, Mohammad E; Kaiser, Karl; Williams, Joshua R; Dellapenna, Timothy M; Louchouarn, Patrick; Santschi, Peter H

2018-06-01

During the 20th century the impacts of industrialization and urbanization in Galveston Bay resulted in significant shifts in trace metals (Hg, Pb, Ni, Zn) and vascular plant biomarkers (lignin phenols) recorded within the surface sediments and sediment cores profile. A total of 22 sediment cores were collected in Galveston Bay in order to reconstruct the historical input of Hg, Pb, Ni, Zn and terrestrial organic matter. Total Hg (T-Hg) concentration ranged between 6 and 162 ng g -1 in surface sediments, and showed decreasing concentrations southward from the Houston Ship Channel (HSC) toward the open estuary. Core profiles of T-Hg and trace metals (Ni, Zn) showed substantial inputs starting in 1905, with peak concentrations between 1960 and 1970's, and decreasing thereafter with exception to Pb, which peaked around 1930-1940s. Stable carbon isotopes and lignin phenols showed an increasing input of terrestrial organic matter driven by urban development within the watershed in the early 1940s. Both the enrichment factor and the geoaccumulation index (I geo ) for T-Hg as a measure of the effectiveness of environmental management practices showed substantial improvements since the 1970s. The natural recovery rate in Galveston Bay since the peak input of T-Hg was non-linear and displayed a slow recovery during the twenty-first century. Copyright © 2018 Elsevier Ltd. All rights reserved.

Chronologically matched toenail-Hg to hair-Hg ratio: temporal analysis within the Japanese community (U.S.

Directory of Open Access Journals (Sweden)

Hinners Thomas

2012-10-01

Full Text Available Abstract Background Toenail-Hg levels are being used as a marker of methylmercury (MeHg exposure in efforts to associate exposure with effects such as cardiovascular disease. There is a need to correlate this marker with more established biomarkers that presently underlie existing dose–response relationships in order to compare these relationships across studies. Methods As part of the Arsenic Mercury Intake Biometric Study, toenail clippings were collected at three time points over a period of one year amongst females from within the population of Japanese living near Puget Sound in Washington State (US. Variability in temporal intra-individual toenail-Hg levels was examined and chronologically matched hair and toenail samples were compared to more accurately define the toxicokinetic variability of Hg levels observed between the two compartments. Results Mean toenail-Hg values (n=43 for the 1st, 2nd and 3rd visits were 0.60, 0.60 and 0.56 ng/mg. Correlations were as follows: r=0.92 between 1st and 2nd clinic visits, r=0.75 between 1st and 3rd visits and r=0.87 between 2nd and 3rd visits. With few exceptions, toenail-Hg values from any visit were within 50-150% of the individual’s mean toenail-Hg level. Nearly all participants had less than a two-fold change in toenail-Hg levels across the study period. A regression model of the relationship between toenail-Hg and hair-Hg (n = 41 levels representing the same time period of exposure, gave a slope (Hg ng/mg of 2.79 for hair relative to toenail (r=0.954. Conclusions A chronologically matched hair-Hg to toenail-Hg ratio has been identified within a population that consumes fish regularly and in quantity. Intra-individual variation in toenail-Hg levels was less than two-fold and may represent dietary-based fluctuations in body burden for individuals consuming various fish species with different contaminant levels. The chronologically matched ratio will be useful for relating MeHg exposure and

Hg-coordination studies of oligopeptides containing cysteine, histidine and tyrosine by $^{199m}$Hg-TDPAC

CERN Document Server

Ctortecka, B; Mallion, S; Butz, T; Hoffmann, R

1999-01-01

In order to study the interaction of histidine- and tyrosine- containing peptide chains with Hg(II), the nuclear quadrupole interaction (NQI) of /sup 199m/Hg in the Hg complexes of the oligopeptides alanyl-alanyl-histidyl-alanyl-alanine-amid (AAHAA-NH /sub 2/) and alanyl-alanyl-tyrosyl-alanyl-alanine-amid (AAYAA-NH/sub 2/) was determined by time differential perturbed angular correlation and is compared with previous data on alanyl-alanyl-cysteyl-alanyl- alanyl (AACAA-OH). The /sup 199m/Hg-NQIs depend on the oligopeptide to Hg(II) stoichiometry and indicate that two-fold and four-fold coordinations occur for the bound Hg(II). (12 refs).

Detailed Assessment of the Kinetics of Hg-Cell Association, Hg Methylation, and Methylmercury Degradation in Several Desulfovibrio Species

Science.gov (United States)

Graham, Andrew M.; Bullock, Allyson L.; Maizel, Andrew C.; Elias, Dwayne A.

2012-01-01

The kinetics of inorganic Hg [Hg(II)i] association, methylation, and methylmercury (MeHg) demethylation were examined for a group of Desulfovibrio species with and without MeHg production capability. We employed a detailed method for assessing MeHg production in cultures, including careful control of medium chemistry, cell density, and growth phase, plus mass balance of Hg(II)i and MeHg during the assays. We tested the hypothesis that differences in Hg(II)i sorption and/or uptake rates drive observed differences in methylation rates among Desulfovibrio species. Hg(II)i associated rapidly and with high affinity to both methylating and nonmethylating species. MeHg production by Hg-methylating strains was rapid, plateauing after ∼3 h. All MeHg produced was rapidly exported. We also tested the idea that all Desulfovibrio species are capable of Hg(II)i methylation but that rapid demethylation masks its production, but we found this was not the case. Therefore, the underlying reason why MeHg production capability is not universal in the Desulfovibrio is not differences in Hg affinity for cells nor differences in the ability of strains to degrade MeHg. However, Hg methylation rates varied substantially between Hg-methylating Desulfovibrio species even in these controlled experiments and after normalization to cell density. Thus, biological differences may drive cross-species differences in Hg methylation rates. As part of this study, we identified four new Hg methylators (Desulfovibrio aespoeensis, D. alkalitolerans, D. psychrotolerans, and D. sulfodismutans) and four nonmethylating species (Desulfovibrio alcoholivorans, D. tunisiensis, D. carbinoliphilus, and D. piger) in our ongoing effort to generate a library of strains for Hg methylation genomics. PMID:22885751

Evidence of Hg-chain formation in HgxTiS2: a 199mHg-TDPAC study

International Nuclear Information System (INIS)

Troeger, W.; Butz, T.; Ouvrard, G.

1993-01-01

We determined the 199m Hg nuclear quadrupole interaction in the ''misfit'' or ''superstoichiometric'' compound Hg x TiS 2 by time differential perturbed angular correlation. A unique Hg-site with ν Q = 511(1) MHz and η = 0.410(4) was observed, irrespective of the Hg-uptake (2/3 ≤ x ≤ 4/3). We propose a model of Hg-Hg zig-zag chains which accounts for these observations as well as for the X-ray diffraction data. (orig.)

A Theoretical Study of the Oxidation of Hg0 to HgBr2 in the Troposphere

DEFF Research Database (Denmark)

Goodsite, M. E.; Plane, J. M C; Skov, H.

2004-01-01

The oxidation of elemental mercury (Hg0) to the divalent gaseous mercury dibromide (HgBr2) has been proposed to account for the removal of Hg0 during depletion events in the springtime Arctic. The mechanism of this process is explored in this paper by theoretical calculations of the relevant rate...... coefficients. Rice-Ramsberger-Kassel-Marcus (RRKM) theory, together with ab initio quantum calculations where required, are used to estimate the following: recombination rate coefficients of Hg with Br, I, and O; the thermal dissociation rate coefficient of HgBr; and the recombination rate coefficients of Hg......Br with Br, I, OH, and O2. A mechanism based on the initial recombination of Hg with Br, followed by the addition of a second radical (Br, I, or OH) in competition with thermal dissociation of HgBr, is able to account for the observed rate of Hg 0 removal, both in Arctic depletion events and at lower...

Optical emission spectroscopy of metal-halide lamps: Radially resolved atomic state distribution functions of Dy and Hg

NARCIS (Netherlands)

Nimalasuriya, T.; Flikweert, A.J.; Stoffels, W.W.; Haverlag, M.; Mullen, van der J.J.A.M.; Pupat, N.B.M.

2006-01-01

Absolute line intensity measurements are performed on a metal-halide lamp. Several transitions of atomic and ionic Dy and atomic Hg are measured at different radial positions from which we obtain absolute atomic and ionic Dy intensity profiles. From these profiles we construct the radially resolved

Accumulation of elements by edible mushroom species: part I. Problem of trace element toxicity in mushrooms.

Science.gov (United States)

Mleczek, Mirosław; Siwulski, Marek; Stuper-Szablewska, Kinga; Rissmann, Iwona; Sobieralski, Krzysztof; Goliński, Piotr

2013-01-01

The aim of this study was to evaluate Cd, Co, Cu, Hg, Ni, Pb, Sr and Zn accumulation in six edible mushroom species and to assess their risk and benefits to human consumers. Mushrooms (Leccinium aurantiacum, Xerocomus badius, Lactarius deliciosus, Boletus edulis, Cantharellus cibarius and Suillus luteus) were collected from selected regions of Poland during 1990-2010. The highest diversity between studied mushroom species was observed in terms of Cu and Zn accumulation. Significant differences in the accumulation efficiency were found among the six mushroom species examined. The most efficient were Boletus edulis (Cd and Hg), Suillus luteus (Cu and Sr), and Lactarius deliciosus (Pb and Zn). In the case of Co and Ni, the most effective were Xerocomus badius and Leccinium aurantiacum, respectively. The calculated bioconcentration factor (BCF) values of Cd, Cu, Hg, Sr and Zn were > 1 for all species in this study while Co, Ni and Pb usually were bioexcluded (BCF luteus collected in Poland is safe and this finding largely agrees with results from recent studies by other authors.

Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J. [Center for Microfibrous Materials Manufacturing, Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

2006-10-27

The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90{sup o}C and at concentrations of 0.100-12.8mol kg{sub H{sub 2}O}{sup -1}. The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25{sup o}C and 1atm are 0.1634V for 0.100m, 0.1077V for 1.00m, and 0.0976V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751V versus NHE and hydrogen evolution potential changes to -0.9916V versus NHE in a solution of 30.0wt.% NaOH at 80{sup o}C. The calculated values are compared with the measured data at 25 and 75{sup o}C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations. (author)

Phytoextraction and accumulation of mercury in three plant species: Indian mustard (Brassica juncea), beard grass (Polypogon monospeliensis), and Chinese brake fern (Pteris vittata).

Science.gov (United States)

Su, Yi; Han, Fengxiang X; Chen, Jian; Sridhar, B B Maruthi; Monts, David L

2008-01-01

The objective of this research was to screen and search for suitable plant species to phytoextract mercury-contaminated soil. Our effort focused on using some of the known metal-accumulating wild-type plants since no natural plant species with mercury-hyperaccumulat ing properties has yet been identified. Three plant species were evaluated for their uptake efficiency for mercury: Indian mustard (Brassica juncea), beard grass (Polypogon monospeliensis), and Chinese brake fern (Pteris vittata). Four sets of experiments were conducted to evaluate the phytoremediation potential of these three plant species: a pot study with potting mix where mercury was provided daily as HgCl2 solution; experiments with freshly mercury-spiked soil; and a study with aged soils contaminated with different mercury sources (HgCl2, Hg(NO3)2, and HgS). Homemade sunlit chambers were also used to study foliar uptake of Hg from ambient air. Among the three plant species, Chinese brake fern showed the least stress symptoms resulting from mercury exposure and had the highest mercury accumulation. Our results indicate that Chinese brake fern may be a potential candidate for mercury phytoextraction. We found that mercury contamination is biologically available for plant uptake and accumulation, even if the original and predominating mercury form is HgS, and also after multiple phytoremediation cycles.

Determination of equilibrium phase composition in the Hg-HgTe-CdTe system by ''dew point'' method

International Nuclear Information System (INIS)

Vanyukov, A.V.; Krotov, I.I.; Ermakov, A.I.

1978-01-01

Using the ''dew point'' method a study has been made of the equilibrium composition of the solid and liquid phases in the Hg-HgTe-CdTe system at 404, 435 and 454 deg C. It has been pointed out that crystallization of cadmium-rich solid solutions of Cdsub(x)Hgsub(1-x) Te takes place from a liquid phase with a much higher concentration of Hg. The activity of Hg in the liquid phase increases along the liquidus isotherm in the direction from section Hg-HgTe to section HgCdTe in accordance with the increase of its concentration. An increase in activity of Hg in the solid phase of Cdsub(x)Hgsub(1-x)Te has been noted with the reduction of its concentration

Mercury toxicokinetics--dependency on strain and gender

DEFF Research Database (Denmark)

Ekstrand, Jimmy; Nielsen, Jesper B; Havarinasab, Said

2010-01-01

regulated by non-H-2 genes and gender. Lymph nodes lacked the strain- and gender-dependent Hg accumulation profile of kidney, liver and spleen. After 15 days without Hg A.SW mice showed a 4-fold higher WBR and liver Hg concentration, but 11-fold higher renal Hg concentration, showing the key role...

Depth Profiling (ICP-MS Study of Toxic Metal Buildup in Concrete Matrices: Potential Environmental Impact

Directory of Open Access Journals (Sweden)

Ghada Bassioni

2010-10-01

Full Text Available This paper explores the potential of concrete material to accumulate toxic trace elements using ablative laser technology (ICP-MS. Concrete existing in offshore structures submerged in seawater acts as a sink for hazardous metals, which could be gradually released into the ocean creating pollution and anoxic conditions for marine life. Ablative laser technology is a valuable tool for depth profiling concrete to evaluate the distribution of toxic metals and locate internal areas where such metals accumulate. Upon rapid degradation of concrete these “hotspots” could be suddenly released, thus posing a distinct threat to aquatic life. Our work simulated offshore drilling conditions by immersing concrete blocks in seawater and investigating accumulated toxic trace metals (As, Be, Cd, Hg, Os, Pb in cored samples by laser ablation. The experimental results showed distinct inhomogeneity in metal distribution. The data suggest that conditions within the concrete structure are favorable for random metal accumulation at certain points. The exact mechanism for this behavior is not clear at this stage and has considerable scope for extended research including modeling and remedial studies.

Resonance broadening of Hg lines as a density diagnostic in high intensity discharge lamps

International Nuclear Information System (INIS)

Lawler, J E

2004-01-01

The use of width measurements on resonance broadened lines of Hg as a density diagnostic in high intensity discharge (HID) lamps is reviewed and further developed in this paper. Optical depths of Hg I lines at 491.6 nm, 577.0 nm, and 1014 nm are computed as a function of temperature to confirm that these lines are optically thin in most HID lamps. The effect of quadratic and quartic radial temperature variation on the width of resonance broadened lines is computed for arc core temperatures from 4000 K to 7000 K. Such variations in temperature, and inverse variations in Hg density, are found to increase the line widths by less than 10% for 'side-on' emission measurements averaged over the arc radius. Theoretical profiles of resonance broadened spectral lines, both radially averaged and as a function of chord offset, are presented. Observations of resonance broadened lines in a metal-halide HID lamp are presented and analysed. It is concluded that the widths of resonance broadened lines provide a convenient and reliable diagnostic for the arc core Hg density but are generally not very sensitive to the radial temperature and Hg density gradient

Phytochelatin synthesis in response to Hg uptake in aquatic plants near a chlor-alkali factory.

Science.gov (United States)

Turull, Marta; Grmanova, Gabriela; Dago, Àngela; Ariño, Cristina; Díez, Sergi; Díaz-Cruz, José Manuel; Esteban, Miquel

2017-06-01

The effects of mercury (Hg) released from a chlor-alkali factory in aquatic plants along the Ebro River basin (NE Spain) were analysed considering the phytochelatins (PC n ) and their isoforms content in these plants. These compounds were analyzed using HPLC with amperometric detection, and the macrophytes species Ceratophyllum demersum and Myriopyllum spicatum were collected in two sampling campaigns, autumn and spring, respectively. To correlate the PC n content in macrophytes with the Hg contamination, analysis of total Hg (THg) content in plants and suspended particulate matter, as well as the dissolved-bioavailable fraction of Hg in water measured by the diffusive gradient in thin film (DGT) technique were done. The results confirm the presence of PC 2 -Ala in extracts of C. demersum and PC 2 -desGly in M. spicatum, and the concentration of these thiol compounds depends clearly on the distance between the hot spot and the downstream sites: the higher the levels are, the closer the hot spot is. Since most of the Hg is hypothesized to be associated with SPM and transported downstream, our results of the DGT suggest that trace amounts of Hg in water can be released as free metal ions yielding a certain accumulation in plants (reaching the ppb level) that are enough for activation of induction of PCs. A few PCs species have been determined, at different seasons, indicating that they can be used as good indicators of the presence of bioavailable Hg in aquatic media throughout the year. Copyright © 2017 Elsevier Ltd. All rights reserved.

Local atomic interdiffusion in CdTe/HgCdTe multilayered structures

International Nuclear Information System (INIS)

Kim, Y.; Ourmazd, A.; Feldman, R.D.; Rentschler, J.A.; Taylor, D.W.; Austin, R.F.

1989-01-01

The authors combine chemical lattice imaging with digital pattern recognition to study atomic interdiffusion at individual CdTe/HgCdTe interfaces in multi-quantum well structures. In this way they obtain quantitative composition profiles for as grown samples, and investigate their development as a function of annealing temperature. The authors' results indicate that interdiffusion depends on the position of the quantum well with respect to the surface, beginning first at quantum wells close to the surface, and proceeding towards the substrate. The authors' approach allows the quantification of interdiffusion as a function of time, temperature, and distance from the surface. The implications of these results for the stability of CdTe/HgCdTe structures, and the interpretation of X-ray data are discussed

The mercury chromates Hg6Cr2O9 and Hg6Cr2O10-Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

International Nuclear Information System (INIS)

Weil, Matthias; Stoeger, Berthold

2006-01-01

The basic mercury(I) chromate(VI), Hg 6 Cr 2 O 9 (=2Hg 2 CrO 4 .Hg 2 O), has been obtained under hydrothermal conditions (200deg. C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K 2 Cr 2 O 7 . Hydrothermal treatment of microcrystalline Hg 6 Cr 2 O 9 in demineralised water at 200deg. C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg 6 Cr 2 O 10 (=2Hg 2 CrO 4 .2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg 6 Cr 2 O 9 : space group P2 1 2 1 2 1 , Z=4, a=7.3573(12), b=8.0336(13), c=20.281(3)A, 3492 structure factors, 109 parameters, R[F 2 >2σ(F 2 )]=0.0371, wR(F 2 all)=0.0517; Hg 6 Cr 2 O 10 : space group Pca2 1 , Z=4, a=11.4745(15), b=9.4359(12), c=10.3517(14)A, 3249 structure factors, 114 parameters, R[F 2 >2σ(F 2 )]=0.0398, wR(F 2 all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg 6 Cr 2 O 9 contains three different Hg 2 2+ dumbbells, whereas Hg 6 Cr 2 O 10 contains two different Hg 2 2+ dumbbells and two Hg 2+ cations. The Hg I -Hg I distances are characteristic and range between 2.5031(15) and 2.5286(9)A. All Hg 2 2+ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg 2+ cations is nearly linear with two tightly bonded O atoms at distances around 2.07A. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66A. Upon heating at temperatures above 385deg. C, Hg 6 Cr 2 O 9 decomposes in a four-step mechanism with Cr 2 O 3 as the end-product at temperatures above 620 deg. C

Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

International Nuclear Information System (INIS)

Gulay, L.D.; Olekseyuk, I.D.; Parasyuk, O.V.

2002-01-01

The crystal structures of Hg 4 SiS 6 and Hg 4 SiSe 6 compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3) deg. for Hg 4 SiS 6 and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3) deg. for Hg 4 SiSe 6 . Atomic parameters were refined in the isotropic approximation (R I =0.0571 and R I =0.0555 for the Hg 4 SiS 6 and Hg 4 SiSe 6 , respectively)

Mercury accumulation in Yellowfin tuna (Thunnus albacares) with regards to muscle type, muscle position and fish size.

Science.gov (United States)

Bosch, Adina C; O'Neill, Bernadette; Sigge, Gunnar O; Kerwath, Sven E; Hoffman, Louwrens C

2016-01-01

The concentrations and relationships between individual mercury species and total mercury were investigated in different muscle parts and sizes of Yellowfin tuna (Thunnus albacares). Fourteen Yellowfin tuna caught in the South Atlantic off the coast of South Africa had an average total Hg (tHg) concentration of 0.77 mg/kg wet weight. No differences were detected (p > 0.05) in tHg, MethylHg (MeHg) or inorganic Hg (iHg) accumulation among the four white muscle portions across the carcass, but both tHg and iHg were found in higher concentrations (p < 0.001) in dark muscle than white muscle. Positive linear correlations with fish weight were found for both tHg (r = 0.79, p < 0.001) and MeHg (r = 0.75, p < 0.001) concentrations. A prediction model was formulated to calculate toxic MeHg concentrations from measured tHg concentrations and fish weight (cMeHg = 0.073 + 1.365 · tHg-0.008 · w). As sampling sites and subsampling methods could affect toxicity measurements, we provide recommendations for sampling guidelines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transcriptome profiling and physiological studies reveal a major role for aromatic amino acids in mercury stress tolerance in rice seedlings.

Directory of Open Access Journals (Sweden)

Yun-An Chen

Full Text Available Mercury (Hg is a serious environmental pollution threat to the planet. The accumulation of Hg in plants disrupts many cellular-level functions and inhibits growth and development, but the mechanism is not fully understood. To gain more insight into the cellular response to Hg, we performed a large-scale analysis of the rice transcriptome during Hg stress. Genes induced with short-term exposure represented functional categories of cell-wall formation, chemical detoxification, secondary metabolism, signal transduction and abiotic stress response. Moreover, Hg stress upregulated several genes involved in aromatic amino acids (Phe and Trp and increased the level of free Phe and Trp content. Exogenous application of Phe and Trp to rice roots enhanced tolerance to Hg and effectively reduced Hg-induced production of reactive oxygen species. Hg induced calcium accumulation and activated mitogen-activated protein kinase. Further characterization of the Hg-responsive genes we identified may be helpful for better understanding the mechanisms of Hg in plants.

Transcriptome profiling and physiological studies reveal a major role for aromatic amino acids in mercury stress tolerance in rice seedlings.

Science.gov (United States)

Chen, Yun-An; Chi, Wen-Chang; Trinh, Ngoc Nam; Huang, Li-Yao; Chen, Ying-Chih; Cheng, Kai-Teng; Huang, Tsai-Lien; Lin, Chung-Yi; Huang, Hao-Jen

2014-01-01

Mercury (Hg) is a serious environmental pollution threat to the planet. The accumulation of Hg in plants disrupts many cellular-level functions and inhibits growth and development, but the mechanism is not fully understood. To gain more insight into the cellular response to Hg, we performed a large-scale analysis of the rice transcriptome during Hg stress. Genes induced with short-term exposure represented functional categories of cell-wall formation, chemical detoxification, secondary metabolism, signal transduction and abiotic stress response. Moreover, Hg stress upregulated several genes involved in aromatic amino acids (Phe and Trp) and increased the level of free Phe and Trp content. Exogenous application of Phe and Trp to rice roots enhanced tolerance to Hg and effectively reduced Hg-induced production of reactive oxygen species. Hg induced calcium accumulation and activated mitogen-activated protein kinase. Further characterization of the Hg-responsive genes we identified may be helpful for better understanding the mechanisms of Hg in plants.

Mercury nonstoichiometry of the Hg1-xBa2CuO4+δ superconductor and the P(Hg)-P(O2)-T phase diagram of the Hg-Ba-Cu-O system

International Nuclear Information System (INIS)

Alyoshin, V.A.; Mikhailova, D.A.; Rudnyi, E.B.; Antipov, E.V.

2002-01-01

The P(Hg)-P(O 2 )-T phase diagram of the Hg-Ba-Cu-O system for the Ba:Cu=2:1 ratio was experimentally studied and followed by means of the thermodynamic modeling. It was shown that the Hg 1-x Ba 2 CuO 4+δ (Hg-1201) superconductor possesses a significant range of Hg-nonstoichiometry and exists in a certain P(Hg), P(O 2 ) and T range. Mercury nonstoichiometry of Hg-1201 was investigated in the 923≤T≤1095 K; 2.0≤P(Hg)≤8.4 atm; 0.09≤P(O 2 )≤0.86 atm ranges. It was found that the mercury content varies in the range of 0.80-0.94 under these conditions. The Gibbs energy of the Hg-1201 phase was estimated as a function of temperature and mercury concentration. The obtained results allow optimizing the synthesis conditions of Hg-1201 with a given Hg-content including preparation of the Hg-stoichiometric phase

Application of epithermal neutron activation analysis to investigate accumulation and adsorption of mercury by Spirulina platensis biomass

International Nuclear Information System (INIS)

Mosulishvili, L.M.; Belokobyl'skij, A.I.; Khizanishvili, A.I.; Frontas'eva, M.V.; Kirkesali, E.I.; Aksenova, N.G.

2004-01-01

Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations ∼100 μg/1

Application of Epithermal Neutron Activation Analysis to Investigate Accumulation and Adsorption of Mercury by Spirulina platensis Biomass

CERN Document Server

Mosulishvili, L M; Khizanishvili, A I; Frontasyeva, M V; Kirkesali, E I; Aksenova, N G

2004-01-01

Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations \\sim 100 {\\mu}g/l.

Sulfurization of Dissolved Organic Matter Increases Hg-Sulfide-Dissolved Organic Matter Bioavailability to a Hg-Methylating Bacterium.

Science.gov (United States)

Graham, Andrew M; Cameron-Burr, Keaton T; Hajic, Hayley A; Lee, Connie; Msekela, Deborah; Gilmour, Cynthia C

2017-08-15

Reactions of dissolved organic matter (DOM) with aqueous sulfide (termed sulfurization) in anoxic environments can substantially increase DOM's reduced sulfur functional group content. Sulfurization may affect DOM-trace metal interactions, including complexation and metal-containing particle precipitation, aggregation, and dissolution. Using a diverse suite of DOM samples, we found that susceptibility to additional sulfur incorporation via reaction with aqueous sulfide increased with increasing DOM aromatic-, carbonyl-, and carboxyl-C content. The role of DOM sulfurization in enhancing Hg bioavailability for microbial methylation was evaluated under conditions typical of Hg methylation environments (μM sulfide concentrations and low Hg-to-DOM molar ratios). Under the conditions of predicted metacinnabar supersaturation, microbial Hg methylation increased with increasing DOM sulfurization, likely reflecting either effective inhibition of metacinnabar growth and aggregation or the formation of Hg(II)-DOM thiol complexes with high bioavailability. Remarkably, Hg methylation efficiencies with the most sulfurized DOM samples were similar (>85% of total Hg methylated) to that observed in the presence of l-cysteine, a ligand facilitating rapid Hg(II) biouptake and methylation. This suggests that complexes of Hg(II) with DOM thiols have similar bioavailability to Hg(II) complexes with low-molecular-weight thiols. Overall, our results are a demonstration of the importance of DOM sulfurization to trace metal and metalloid (especially mercury) fate in the environment. DOM sulfurization likely represents another link between anthropogenic sulfate enrichment and MeHg production in the environment.

Investigation of Hg uptake and transport between paddy soil and rice seeds combining Hg isotopic composition and speciation

OpenAIRE

C. Feng; Z. Pedrero; P. Li; B. Du; X. Feng; M. Monperrus; E. Tessier; S. Berail; D. Amouroux

2016-01-01

Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg) polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg) in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations withi...

Collective structures in 185Hg

International Nuclear Information System (INIS)

Bourgeois, C.; Hildingsson, L.; Perrin, N.; Sergolle, H.; Hannachi, F.; Bastin, G.; Porquet, M.G.; Thibaud, J.P.; Beck, F.A.; Merdinger, J.C.

1988-01-01

Excited states of 185 Hg have been investigated via the 161 Dy ( 28 Si, 4n) reaction at 145 MeV. In-beam gamma-ray spectroscopy studies have been performed with the ''Chateau de Cristal'' 4π-multidetector array. Level scheme of 185 Hg has been established. Shape coexistence, still present in 185 Hg like in the neighbouring Hg isotopes, manifests itself through a weakly populated decoupled band built on the 13/2+ isomer and three strongly-coupled bands built on the prolate 1/2-[521], 7/2-[514], and 9/2+[624] Nilsson states

Genome-wide RNA polymerase II profiles and RNA accumulation reveal kinetics of transcription and associated epigenetic changes during diurnal cycles.

Directory of Open Access Journals (Sweden)

Gwendal Le Martelot

Full Text Available Interactions of cell-autonomous circadian oscillators with diurnal cycles govern the temporal compartmentalization of cell physiology in mammals. To understand the transcriptional and epigenetic basis of diurnal rhythms in mouse liver genome-wide, we generated temporal DNA occupancy profiles by RNA polymerase II (Pol II as well as profiles of the histone modifications H3K4me3 and H3K36me3. We used these data to quantify the relationships of phases and amplitudes between different marks. We found that rhythmic Pol II recruitment at promoters rather than rhythmic transition from paused to productive elongation underlies diurnal gene transcription, a conclusion further supported by modeling. Moreover, Pol II occupancy preceded mRNA accumulation by 3 hours, consistent with mRNA half-lives. Both methylation marks showed that the epigenetic landscape is highly dynamic and globally remodeled during the 24-hour cycle. While promoters of transcribed genes had tri-methylated H3K4 even at their trough activity times, tri-methylation levels reached their peak, on average, 1 hour after Pol II. Meanwhile, rhythms in tri-methylation of H3K36 lagged transcription by 3 hours. Finally, modeling profiles of Pol II occupancy and mRNA accumulation identified three classes of genes: one showing rhythmicity both in transcriptional and mRNA accumulation, a second class with rhythmic transcription but flat mRNA levels, and a third with constant transcription but rhythmic mRNAs. The latter class emphasizes widespread temporally gated posttranscriptional regulation in the mouse liver.

46 CFR 53.05-1 - Safety valve requirements for steam boilers (modifies HG-400 and HG-401).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG-400 and HG-401). 53.05-1 Section 53.05-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the...

Hg0 and HgCl2 Reference Gas Standards: NIST Traceability and Comparability (And EPA ALT Methods for Hg and HCl )

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the tru...

Choroid plexus accumulates cadmium, lead, mercury and arsenic

International Nuclear Information System (INIS)

Zheng, W.; Perry, D.F.; Nelson, D.L.; Aposhian, H.V.

1990-01-01

The choroid plexus (CP) is the site of the formation of cerebrospinal fluid (CSF) and the major location of the blood-CSF barrier. The property of CP in sequestering heavy metals so as to prevent their entering CSF was studied in male rats and rabbits. The content of Cd, Pb and Hg in rat tissues was determined by AAS and radioactive isotopes 24 hours after a single exposure. Cd was 33 fold greater in CP than in brain cortex (BC) after 4 mg Cd/kg ip. No Cd was detected in CSF. In rats given 27 mg Pb/kg ip, Pb in CP was 57 fold greater than in BC and 12 fold greater in blood than CSF. Rats exposed to 1 mg Hg/kg ip showed a 13 fold greater Hg content in CP than in BC. Hg was 78 fold lower in CSF than in blood. Arsenic distribution in rabbits was determined 4 hours after iv injection of 1.7 mg As 5+ /kg. As in CP was 6 fold greater than in BC and in blood it was 26 fold more than in CSF. Total thiol content in BC was significantly higher than that in CP. In CP, 87% of total thiol was non-protein bound thiol. Results suggest that the CP accumulates toxic metals such as Cd, Pb, Hg and As and acts as a filter to limit these metals passing through the blood-CSF barrier. CdCl 2 , Pb acetate, HgCl 2 or Na arsenate was used for injection

Use of new threshold detector 199Hg(n,n')/sup 199m/Hg for neutron spectrum unfolding

International Nuclear Information System (INIS)

Sakurai, K.

1982-01-01

The nuclear data for the 199 Hg(n,n')/sup 199m/Hg reaction are reviewed and the data are used for neutron spectrum unfolding. The neutron spectrum of the YAYOI glory-hole is unfolded by SAND II with 10 nuclear reactions including the 199 Hg(n,n')/sup 199m/Hg reaction. The ratio of the measured reaction rate to the calculated reaction rate is about 1:1.1 for the guess spectrum. The 199 Hg(n,n')/sup 199m/Hg, 115 In(n,n')/sup 115m/In, 103 Rh(n,n')/sup 103m/Rh reactions should be useful threshold detectors for the neutron dosimetry with low level fast neutron flux

The application of ¹⁹⁹Hg NMR and ^199mHg perturbed angular correlation (PAC) spectroscopy to define the biological chemistry of Hg^II

DEFF Research Database (Denmark)

Iranzo, Olga; Thulstrup, Peter Waaben; Ryu, Seung-baek

2007-01-01

The use of de novo designed peptides is a powerful strategy to elucidate HgII-protein interactions and to gain insight into the chemistry of HgII in biological systems. Cysteine derivatives of the designed -helical peptides of the TRI family [Ac-G-(LaKbAcLdEeEfKg)4-G-NH2] bind HgII at high p...... to characterize the distinct species that are generated under different pH conditions and peptide TRI L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI L9C)2-(TRI L9C H)}], a dithiolate-HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI L9C)3. 199Hg NMR...

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

International Nuclear Information System (INIS)

Lapanje, A.; Drobne, D.; Nolde, N.; Valant, J.; Muscet, B.; Leser, V.; Rupnik, M.

2008-01-01

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 μg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

Energy Technology Data Exchange (ETDEWEB)

Lapanje, A. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia)], E-mail: ales.lapanje@bf.uni-lj.si; Drobne, D. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Nolde, N. [Institute Jozef Stefan, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana (Slovenia); Valant, J. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Muscet, B. [Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia); Leser, V. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Rupnik, M. [Institute of Public Health, Prvomajska 1, 2000 Maribor (Slovenia); Faculty of Medicine, University of Maribor, Slomskov trg 15, 2000 Maribor (Slovenia)

2008-06-15

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 {mu}g Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant.

Mercury accumulation in sharks from the coastal waters of southwest Florida.

Science.gov (United States)

Rumbold, Darren; Wasno, Robert; Hammerschlag, Neil; Volety, Aswani

2014-10-01

As large long-lived predators, sharks are particularly vulnerable to exposure to methylmercury biomagnified through the marine food web. Accordingly, nonlethal means were used to collect tissues for determining mercury (Hg) concentrations and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) from a total of 69 sharks, comprising 7 species, caught off Southwest Florida from May 2010 through June 2013. Species included blacknose (Carcharhinus acronotus), blacktip (C. limbatus), bull (C. leucas), great hammerhead (Sphyrna mokarran), lemon (Negaprion brevirostris), sharpnose (Rhizoprionodon terraenovae), and tiger sharks (Galeocerdo cuvier). The sharks contained Hg concentrations in their muscle tissues ranging from 0.19 mg/kg (wet-weight basis) in a tiger shark to 4.52 mg/kg in a blacktip shark. Individual differences in total length and δ(13)C explained much of the intraspecific variation in Hg concentrations in blacknose, blacktip, and sharpnose sharks, but similar patterns were not evident for Hg and δ(15)N. Interspecific differences in Hg concentration were evident with greater concentrations in slower-growing, mature blacktip sharks and lower concentrations in faster-growing, young tiger sharks than other species. These results are consistent with previous studies reporting age-dependent growth rate can be an important determinant of intraspecific and interspecific patterns in Hg accumulation. The Hg concentrations observed in these sharks, in particular the blacktip shark, also suggested that Hg may pose a threat to shark health and fitness.

Search for an Electric Dipole Moment (EDM) of 199Hg

Science.gov (United States)

Heckel, Blayne

2017-04-01

The observation of a non-zero EDM of an atom or elementary particle, at current levels of experimental sensitivity, would imply CP violation beyond the CKM matrix of the standard model of particle physics. Additional sources of CP violation have been proposed to help explain the excess of matter over anti-matter in our universe and the magnitude of ΘQCD, the strength of CP violation in the strong interaction, remains unknown. We have recently completed a set of measurements on the EDM of 199Hg, sensitive to both new sources of CP violation and ΘQCD. The experiment compares the phase accumulated by precessing Hg spins in vapor cells with electric fields parallel and anti-parallel to a common magnetic field. Our new result represents a factor of 5 improvement over previous results. A description of the EDM experiment, data, systematic error considerations will be presented. This work was supported by NSF Grant No. 1306743 and by the DOE Office of Nuclear Physics under Award No. DE-FG02-97ER41020.

HgTe based topological insulators

International Nuclear Information System (INIS)

Bruene, Christoph

2014-01-01

This PhD thesis summarizes the discovery of topological insulators and highlights the developments on their experimental observations. The work focuses on HgTe. The thesis is structured as follows: - The first chapter of this thesis will give a brief overview on discoveries in the field of topological insulators. It focuses on works relevant to experimental results presented in the following chapters. This includes a short outline of the early predictions and a summary of important results concerning 2-dimensional topological insulators while the final section discusses observations concerning 3-dimensional topological insulators. - The discovery of the quantum spin Hall effect in HgTe marked the first experimental observation of a topological insulator. Chapter 2 focuses on HgTe quantum wells and the quantum spin Hall effect. The growth of high quality HgTe quantum wells was one of the major goals for this work. In a final set of experiments the spin polarization of the edge channels was investigated. Here, we could make use of the advantage that HgTe quantum well structures exhibit a large Rashba spin orbit splitting. - HgTe as a 3-dimensional topological insulator is presented in chapter 3. - Chapters 4-6 serve as in depth overviews of selected works: Chapter 4 presents a detailed overview on the all electrical detection of the spin Hall effect in HgTe quantum wells. The detection of the spin polarization of the quantum spin Hall effect is shown in chapter 5 and chapter 6 gives a detailed overview on the quantum Hall effect originating from the topological surface state in strained bulk HgTe.

Novel Hg2+-Induced Nephropathy in Rats and Mice Lacking Mrp2: Evidence of Axial Heterogeneity in the Handling of Hg2+ Along the Proximal Tubule

Science.gov (United States)

Zalups, Rudolfs K.; Joshee, Lucy; Bridges, Christy C.

2014-01-01

The role of the multi-resistance protein 2 (Mrp2) in the nephropathy induced by inorganic mercuric mercury (Hg2+) was studied in rats (TR−) and mice (Mrp2−/−), which lack functional Mrp2, and control animals. Animals were exposed to nephrotoxic doses of HgCl2. Forty-eight or 24 hours after exposure, tissues were harvested and analyzed for Hg content and markers of injury. Histological analyses revealed that the proximal tubular segments affected pathologically by Hg2+ were significantly different between Mrp2-deficient animals and controls. In the absence of Mrp2, cellular injury localized almost exclusively in proximal tubular segments in the subcapsular (S1) to midcortical regions (early S2) of the kidney. In control animals, cellular death occurred mainly in the proximal tubular segments in the inner cortex (late S2) and outer stripe of the outer medulla (S3). These differences in renal pathology indicate that axial heterogeneity exists along the proximal tubule with respect to how mercuric ions are handled. Total renal and hepatic accumulation of mercury was also greater in animals lacking Mrp2 than in controls, indicating that Mrp2 normally plays a significant role in eliminating mercuric ions from within proximal tubular cells and hepatocytes. Analyses of plasma creatinine, BUN, and renal expression of Kim-1 and Ngal tend to support the severity of the nephropathies detected histologically. Collectively, our findings indicate that a fraction of mercuric ions is normally secreted by Mrp2 in early portions of proximal tubules into the lumen and then is absorbed downstream in straight portions, where mercuric species typically induce toxic effects. PMID:25145654

Sudden change of quadrupole moment between the first 5/2- states of 197Hg and 199Hg

International Nuclear Information System (INIS)

Herzog, P.; Krien, K.; Freitag, M.; Reuschenbach, M.; Walitzki, H.

1980-01-01

Low-temperature time differential perturbed angular correlation experiments with the 164 KeV-134 keV cascade of sup(197m)Hg in a zinc matrix give evidence that the hitherto accepted value of the quadrupole moment of the first 5/2 - state of 197 Hg is erroneous. A new value is derived from a time differential perturbed angular correlation experiment with the 374 keV-158 keV cascade of sup(199m)Hg implanted into a Be single crystal and comparison with an analogous experiment for sup(197m)Hg. Taking Q(5/2 - , 199 Hg) = +0.95(7) b we derive Q(5/2 - , 197 Hg) = 0.081(6) b. This change of quadrupole moment is discussed in the framework of the shell model. (orig.)

Phase equilibria and thermodynamic functions for Ag–Hg and Cu–Hg binary systems

International Nuclear Information System (INIS)

Liu, Yajun; Wang, Guan; Wang, Jiang; Chen, Yang; Long, Zhaohui

2012-01-01

Highlights: ► The thermodynamic properties of Ag–Hg and Cu–Hg are explored in order to facilitate dental materials design. ► A self-consistent set of thermodynamic parameters is obtained. ► The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag–Hg and Cu–Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

Phase equilibria and thermodynamic functions for Ag-Hg and Cu-Hg binary systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Guan [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Jiang [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Chen, Yang [Mining, Metallurgy and Materials Research Department, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Long, Zhaohui [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

2012-11-10

Highlights: Black-Right-Pointing-Pointer The thermodynamic properties of Ag-Hg and Cu-Hg are explored in order to facilitate dental materials design. Black-Right-Pointing-Pointer A self-consistent set of thermodynamic parameters is obtained. Black-Right-Pointing-Pointer The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag-Hg and Cu-Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

A study of capillary discharge lamps in Ar-Hg and Xe-Hg mixtures

International Nuclear Information System (INIS)

Denisova, N; Gavare, Z; Revalde, G; Skudra, Ja; Veilande, R

2011-01-01

Low-pressure capillary discharge lamps in Ar-Hg and Xe-Hg mixtures are studied. The discharge size is 0.5 mm (500 μm) in radius. According to the literature, such types of plasma sources are classified as microplasmas. The studies include spectrally resolved optical measurements, tomographic reconstructions and numerical simulations using the collisional-radiative model for an Ar-Hg plasma. We discuss the problems of theoretical modelling and experimental diagnostics of microplasma sources. It is shown that the conventional collisional-radiative model, based on the assumption that transportation of atoms in the highly excited states can be neglected, has limitations in modelling a capillary discharge in an Ar-Hg mixture. It is found that diffusion of highly excited mercury atoms to the wall influences the emission properties of the capillary discharge. We have concluded that applications of the emission tomography method to microplasmas require a special analysis in each particular case.

Isotopic Hg in an Allende carbon-rich residue

Science.gov (United States)

Reed, G. W., Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body.

Multielemental accumulation and its intracellular distribution in tissues of some aquatic birds

International Nuclear Information System (INIS)

Nam, Dong-Ha; Anan, Yasumi; Ikemoto, Tokutaka; Tanabe, Shinsuke

2005-01-01

This study was aimed at determining multielemental concentration and its intracellular distribution in selected tissues of cormorant and waterfowl species. Non-essential elements such as Hg, Tl, Cd, Pb and V in tissues were generally consistent with those in ingested items, indicating the significance of food sources of non-essential metal accumulation in great cormorants and mallards. Great cormorants and four waterfowl species examined reflected natural background levels of toxic metals such as Cd, Hg and Pb as well as some essential elements, indicating no specific metal exposure from local sources. Most of Cu, Zn, Se, Rb, Ag, Cd, Cs, and Hg contents were present in the hepatocytosolic fraction, whereas a large percentage of V and Mo were present in insoluble fraction in great cormorant, mallard, and spot-billed duck. The major role of these subcelluar fractions in elemental regulation accounts for the high percentage contribution of each cellular fraction to the total metal contents. Cadmium and Cu are chiefly sequestered through binding to metallothioneins (MTs) of hepatocytosolic fraction in these three avian species. Both MTs and high-molecular-weight substance (HMWS) for Zn and low-molecular-weight substance (LMWS) for Rb were also involved in their sequestration in cytosolic fractions. Relatively different species-specific cytosolic substances were responsible for varying degrees of Ag, Mn, and Co accumulation. It is worth noting that these intracellular metal levels in birds are closely regulated by metal-associated cellular constituents. Therefore, risk assessment studies of metal accumulation in such wild birds should take intracellular metal distribution and specific cellular constituents into account

An investigation of mercury sources in the Puyango-Tumbes River: Using stable Hg isotopes to characterize transboundary Hg pollution.

Science.gov (United States)

Schudel, Gary; Miserendino, Rebecca Adler; Veiga, Marcello M; Velasquez-López, P Colon; Lees, Peter S J; Winland-Gaetz, Sean; Davée Guimarães, Jean Remy; Bergquist, Bridget A

2018-07-01

Mercury (Hg) concentrations and stable isotopes along with other trace metals were examined in environmental samples from Ecuador and Peru's shared Puyango-Tumbes River in order to determine the extent to which artisanal- and small-scale gold mining (ASGM) in Portovelo-Zaruma, Ecuador contributes to Hg pollution in the downstream aquatic ecosystem. Prior studies investigated the relationship between ASGM activities and downstream Hg pollution relying primarily on Hg concentration data. In this study, Hg isotopes revealed an isotopically heavy Hg signature with negligible mass independent fractionation (MIF) in downstream sediments, which was consistent with the signature observed in the ASGM source endmember. This signature was traced as far as ∼120 km downstream of Portovelo-Zaruma, demonstrating that Hg stable isotopes can be used as a tool to fingerprint and trace sources of Hg over vast distances in freshwater environments. The success of Hg isotopes as a source tracer in fresh waters is largely due to the particle-reactive nature of Hg. Furthermore, the magnitude and extent of downstream Hg, lead, copper and zinc contamination coupled with the Hg isotopes suggest that it is unlikely that the smaller artisanal-scale activities, which do not use cyanidation, are responsible for the pollution. More likely it is the scale of ores processed and the cyanide leaching, which can release other metals and enhance Hg transport, used during small-scale gold mining that is responsible. Thus, although artisanal- and small-scale gold mining occur in tandem in Portovelo-Zaruma, a distinction should be made between these two activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorption of mercury compounds by tropical soils. I. Adsorption in soil profiles in relation to their physical, chemical, and mineralogical properties

Energy Technology Data Exchange (ETDEWEB)

Semu, E.; Singh, B.R.; Selmer-Olsen, A.R.

1986-01-01

Mercury adsorption of HgCl/sub 2/ and 2-methoxyethylmercury chloride (Aretan) (100 mg Hg L/sup -1/) was measured for three soil profiles from Morogoro, Arusha, and Dar es Salaam in Tanzania. The adsorption was investigated for the physical, chemical, and mineralogical properties of soils. All soil samples showed greater capacity for adsorption of Aretan than for HgCl/sub 2/. In the Morogoro profile Hg adsorption decreased with depth but in the other two soils, the minimum adsorption occurred in the third horizon and increased both upwards and downwards. In the Morogoro profile, Aretan adsorption correlated well with pH. Adsorption of both Aretan and HgCl/sub 2/ correlated well with the distribution of organic C and with the cation exchange capacity of the soils. In the Arusha and Dar es Salaam profiles Hg adsorption was not significantly correlated with any of the soil properties tested.

Electric field gradients in Hg compounds

DEFF Research Database (Denmark)

Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

2012-01-01

&H functional performs best at both 4-component and ZORA levels. We furthermore observe that changes in the largest component of the diagonalised EFG tensor, Vzz, of linear HgCl2 show a slightly stronger dependence than the r-3 scaling upon bond length r(Hg-Cl) alterations. The 4-component/BH&H Vzz value of -9.......26 a.u. for a bent HgCl2 (¿ Cl-Hg-Cl = 120¿) is close to -9.60 a.u. obtained for the linear HgCl2 structure. Thus a point charge model for EFG calculations completely fails in this case. By means of a projection analysis of molecular orbital (MO) contributions to Vzz in terms of the atomic constituents...

Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

Science.gov (United States)

Perrot, Vincent; Masbou, Jeremy; Pastukhov, Mikhail V; Epov, Vladimir N; Point, David; Bérail, Sylvain; Becker, Paul R; Sonke, Jeroen E; Amouroux, David

2016-02-01

In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

Isotopic Hg in an Allende carbon-rich residue

International Nuclear Information System (INIS)

Reed, G.W. Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body. 9 refs

40 CFR 60.4142 - Hg allowance allocations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Hg allowance allocations. 60.4142... Coal-Fired Electric Steam Generating Units Hg Allowance Allocations § 60.4142 Hg allowance allocations. (a)(1) The baseline heat input (in MMBtu) used with respect to Hg allowance allocations under...

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films.

Science.gov (United States)

Rahman, Nazia; Sato, Nobuhiro; Sugiyama, Masaaki; Hidaka, Yoshiki; Okabe, Hirotaka; Hara, Kazuhiro

2014-01-01

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

Short-term responses to watershed logging on biomass mercury and methylmercury accumulation by periphyton in boreal lakes

Energy Technology Data Exchange (ETDEWEB)

Desrosiers, M.; Planas, D. [Quebec Univ., Montreal, PQ (Canada). Dept. de sciences biologiques; Mucci, A. [McGill Univ., Montreal, PQ (Canada). Dept. of Earth and Planetary Sciences

2006-08-15

Increased timber harvesting in the boreal regions of Quebec may have a significant impact on aquatic ecosystems. Watershed disturbances such as logging increase chemical loading to lakes. Soil in the Canadian Shield readily adsorbs and accumulates mercury (Hg) from atmospheric deposition. Forest watersheds serve as large reservoirs of Hg that shed their metal load when soil and land hydrology are disrupted. This paper presented the results of a study evaluating the impact of logging on periphyton algal biomass and dry mass. The study also evaluated the impact of total mercury (THG) and methylmercury (MeHg) accumulation in the littoral zone of the boreal lakes. A before-after control-impact (BACI) sample design was applied that required data from control and target sites sampled both before and after the disturbances. The study was carried out on 18 boreal lakes located in the Grenville geological province. Eight lakes had their watersheds logged over 15 to 79 per cent of their area. A further 10 lakes were used as control sites to document interannual variations. The project used water quality and physiographic data acquired by research groups within the Sustainable Forest Management Network. Fourteen study lakes were sampled once a year during 2 consecutive ice-free seasons before and after logging, and another 4 lakes were sampled 2 years after logging. Significant decreases in algal biomass and increases in MeHg concentrations in periphyton mats in a majority of the harvested watershed lakes were detected. The increases may have a significant impact on organisms of higher trophic levels as they are at the base of the food web. Results suggested that the observed decrease in periphyton biomass combined with the increase in MeHg accumulation may magnify the impact of logging activities on fish and other aquatic predators. Two years after logging, it was observed that MeHg concentrations were still increasing. It was concluded that further research is needed

Oxidative stress in MeHg-induced neurotoxicity

Energy Technology Data Exchange (ETDEWEB)

Farina, Marcelo, E-mail: farina@ccb.ufsc.br [Departamento de Bioquimica, Centro de Ciencias Biologicas, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States); Rocha, Joao B.T., E-mail: jbtrocha@yahoo.com.br [Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS (Brazil)

2011-11-15

Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically

Enhanced Hg{sup 2+} removal and Hg{sup 0} re-emission control from wet fuel gas desulfurization liquors with additives

Energy Technology Data Exchange (ETDEWEB)

Tingmei Tang; Jiang Xu; Rongjie Lu; Jingjing Wo; Xinhua Xu [Zhejiang University, Hangzhou (China). Department of Environmental Engineering

2010-12-15

Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg{sup 2+} to Hg{sup 0}. The present study employed three agents: Na{sub 2}S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg{sup 2+} in simulated desulfurization solutions. The effects of the precipitator's dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl{sup -} and other metal ions (e.g. Cu{sup 2+} and Pb{sup 2+}) on Hg{sup 2+} removal were studied. A linear relationship was observed between Hg{sup 2+} removal efficiency and the increasing precipitator's doses along with initial pH. The addition of chloride and metal ions impaired the Hg{sup 2+} removal from solutions due to the complexation of Cl{sup -} and Hg{sup 2+} as well as the chelating competition between Hg{sup 2+} and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg{sup 2+} reduction as well as Hg{sup 0} re-emission from FGD liquors. More than 90% Hg{sup 2+} was captured by precipitating agents while Hg{sup 2+} reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg{sup 0} pollution from FGD liquors. 21 refs., 6 figs.

The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution.

Science.gov (United States)

Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Sen; Ci, Zhijia; Kong, Xiangrui; Wang, Zhangwei

2013-09-01

One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p  0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g(-1), respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m(-3).

Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

Science.gov (United States)

Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

2013-07-02

The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

A macroalgae-based biotechnology for water remediation: Simultaneous removal of Cd, Pb and Hg by living Ulva lactuca.

Science.gov (United States)

Henriques, Bruno; Rocha, Luciana S; Lopes, Cláudia B; Figueira, Paula; Duarte, A C; Vale, Carlos; Pardal, M A; Pereira, E

2017-04-15

Metal uptake from contaminated waters by living Ulva lactuca was studied during 6 days, under different relevant contamination scenarios. In mono-metallic solutions, with concentrations ranging from 10 to 100 μg L -1 for Hg, 10-200 μg L -1 for Cd, and 50-1000 μg L -1 for Pb, macroalgae (500 mg L -1 , d.w.) were able to remove, in most cases 93-99% of metal, allowing to achieve water quality criteria regarding both surface and drinking waters. In multi-metallic solutions, comprising simultaneously the three metals, living macroalgae still performed well, with Hg removal (c.a. 99%) not being significantly affected by the presence of Cd and Pb, even when those metals were in higher concentrations. Removal efficiencies for Cd and Pb varied between 57 and 96%, and 34-97%, respectively, revealing an affinity of U. lactuca toward metals: Hg > Cd > Pb. Chemical quantification in macroalgae, after bioaccumulation assays demonstrated that all Cd and Hg removed from solution was really bound in macroalgae biomass, while only half of Pb showed to be sorbed on the biomass. Overall, U. lactuca accumulated up to 209 μg g -1 of Hg, up to 347 μg g -1 of Cd and up to 1641 μg g -1 of Pb, which correspond to bioconcentration factors ranging from 500 to 2200, in a dose-dependent accumulation. Pseudo-first order, pseudo-second order and Elovich models showed a good performance in describing the kinetics of bioaccumulation, in the whole period of time. In the range of experimental conditions used, no mortality was observed and U. lactuca relative growth rate was not significantly affected by the presence of metals. Results represent an important contribution for developing a macroalgae-based biotechnology, applied for contaminated saline water remediation, more "green" and cost-effective than conventional treatment methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hg L3 XANES Study of Mercury Methylation in Shredded Eichhornia Crassipes

International Nuclear Information System (INIS)

Rajan, M.; Darrow, J.; Hua, M.; Barnett, B.; Mendoza, M.; Greenfield, B.K.; Andrews, J.C.

2008-01-01

Eichhornia crassipes (water hyacinth) is a non-native plant found in abundance in the Sacramento-San Joaquin River Delta (hereafter called Delta). This species has become a problem, clogging waterways and wetlands. Water hyacinth are also known to accumulate mercury. Recent attempts to curb its proliferation have included shredding with specialized boats. The purpose of this research is to better understand the ability of water hyacinth to phytoremediate mercury and to determine the effect of shredding and anoxic conditions on mercury speciation in plant tissue. In the field assessment, total mercury levels in sediment from the Dow Wetlands in the Delta were found to be 0.273 ± 0.070 ppm Hg, and levels in hyacinth roots and shoots from this site were 1.17 ± 0.08 ppm and 1.03 ± 0.52 ppm, respectively, indicating bioaccumulation of mercury. Plant samples collected at this site were also grown in nutrient solution with 1 ppm HgCl 2 under (1) aerobic conditions, (2) anaerobic conditions, and (3) with shredded plant material only. The greatest accumulation was found in the roots of whole plants. Plants grown in these conditions were also analyzed at Stanford Synchrotron Radiation Laboratory using Hg L 3 X-ray Absorption Near Edge Spectroscopy (XANES), a method to examine speciation that is element-specific and noninvasive. Least-squares fitting of the XANES data to methylated and inorganic mercury(II) model compounds revealed that in plants grown live and aerobically, 5 ± 3% of the mercury was in the form of methylmercury, in a form similar to methylmercury cysteine. This percentage increased to 16 ± 4% in live plants grown anaerobically and to 22 ± 6% in shredded anaerobic plants. We conclude that shredding of the hyacinth plants and, in fact, subjection of plants to anaerobic conditions (e.g., as in normal decay, or in crowded growth conditions) increases mercury methylation. Mechanical removal of the entire plant is significantly more expensive than shredding

Fully relativistic coupled cluster and DFT study of electric field gradients at Hg in 199Hg compounds

DEFF Research Database (Denmark)

Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

2012-01-01

We investigate the magnitude and interplay of relativistic and electron correlation effects on the electric field gradient (EFG) at the position of Hg in linear and bent HgL2 (L=CH3, Cl, Br, I) and trigonal planar [HgCl3]- complexes using four-component relativistic Dirac-Coulomb (DC) and non...

Converting Hg-1212 to Tl-2212 via Tl-Hg cation exchange in combination with Tl cation intercalation

International Nuclear Information System (INIS)

Zhao Hua; Wu, Judy Z

2007-01-01

In a cation exchange process developed recently for epitaxy of HgBa 2 CaCu 2 O 6 (Hg-1212) thin films, TlBa 2 CaCu 2 O 7 (Tl-1212) or Tl 2 Ba 2 CaCu 2 O 9 (Tl-2212) precursor films were employed as the precursor matrices and Hg-1212 was obtained by replacing Tl cations on the precursor lattice with Hg cations. The reversibility of the cation exchange dictates directly the underlying mechanism. Following our recent success in demonstrating a complete reversibility within '1212' structure, we show the conversion from Hg-1212 to Tl-2212 can be achieved via two steps: conversion from Hg-1212 to Tl-1212 followed by Tl intercalation to form double Tl-O plans in each unit cell. The demonstrated reversibility of the cation exchange process has confirmed the process is a thermal perturbation of weakly bonded cations on the lattice and the direction of the process is determined by the population ratio between the replacing cations and that to be replaced

Determination of subnanomolar levels of mercury (II) by using a graphite paste electrode modified with MWCNTs and Hg(II)-imprinted polymer nanoparticles.

Science.gov (United States)

Alizadeh, Taher; Hamidi, Negin; Ganjali, Mohamad Reza; Rafiei, Faride

2017-12-05

Mercury ion-imprinted polymer nanoparticles (Hg-IP-NPs) were synthesized via precipitation polymerization by using itaconic acid as a functional monomer. A carbon paste electrode was impregnated with the synthesized Hg-IP-NPs and MWCNTs to obtain a highly sensitive and selective electrode for determination of Hg(II). Mercury ion is first accumulated on the electrode surface via an open circuit procedure. After reduction of Hg(II) ions to its metallic form at a negative pre-potential, square wave anodic stripping voltammetry was applied to generate the electrochemical signal. The high affinity of the Hg-IP-NPs for Hg(II) was substantiated by comparing of the signals of electrodes with imprinted and non-imprinted polymer. The beneficial effect of MWCNTs on the voltammetric signal is also demonstrated. Under the optimized conditions and at a typical working potential of +0.05 V (vs. Ag/AgCl), the electrode has a linear response in the 0.1-20 nmol L -1 Hg(II) concentration range and a 29 pM detection limit. The electrochemical sensitivity is as high as 1441 A·M -1 ·cm -2 which is among the best values known. The electrode was applied to the determination of Hg(II) in water samples. Graphical abstract Schematic representation of the sensor electrode modified with mercury-imprinted polymer nanoparticles, and the recognition and voltammetric determination steps.

Selection of mercury accumulator plants for gold mine tailing contaminated soils

Directory of Open Access Journals (Sweden)

N Muddarisna

2015-04-01

Full Text Available Phytoremediation, which is more efficient with less side effects than conventional physical and chemical methods, is increasing in popularity as a remediation system. This paper provides a brief overview of developments in research and application of phytoremediation of soil contaminated with gold mine tailings containing mercury. Lindernia crustacea L., Digitaria radicosa Presl. Miq., Zingiber purpurium L, Paspalum conjugatum Berg., Cyperus kyllingia Endl., and Caladium bicolor Vent., that were selected for this study were planted in the planting media consisting of soil (70% and tailings (30% for 9 weeks. The results showed that after 9 weeks of planting, Paspalum conjugatum had growth rate, biomass production, Hg accumulation, and ratio of shoot Hg : root Hg higher than those of other plant species tested, both in the media consisted of amalgamation and cyanidation tailings. It can thus be concluded that Paspalum conjugatum is potential plant species for remediating mercury-contaminated soil.

Ab initio study of structural, electronic and optical properties of MnHg(SCN)4 and FeHg(SCN)4

International Nuclear Information System (INIS)

He, K.H.; Zheng, G.; Chen, G.; Lue, T.; Wan, M.; Ji, G.F.

2007-01-01

The structural, electronic and optical properties of MnHg(SCN) 4 and FeHg(SCN) 4 were studied by means of quantum-mechanical calculations based on the density-functional theory and pseudopotential method. The lattice constants can be compared with the experimental values when the effects of temperature are considered. The peaks of partial density of states of S, C, N and Hg of FeHg(SCN) 4 have a tendency of shifting to the higher energy levels relative to those of MnHg(SCN) 4 . The distributions of the 3d electronic states in the transition metal atoms show quite large difference and decide different optical properties. We found that absorptional peaks of FeHg(SCN) 4 lag behind those of MnHg(SCN) 4 and the peak in the infrared range has a higher absorptional intensity, which are in accord with the experimental results. By analyzing the distributions and transitions of the 3d electronic states, we explained the different absorption phenomena

Hg(+) Frequency Standards

Science.gov (United States)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

Hg transfer from contaminated soils to plants and animals

NARCIS (Netherlands)

Rodrigues, S.M.; Henriques, B.; Reis, A.T.; Duarte, A.C.; Pereira, E.; Romkens, P.F.A.M.

2012-01-01

Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant

Oblate shapes of 200,202,204Hg

International Nuclear Information System (INIS)

Bockisch, A.; Bharuth-Ram, K.; Kleinfeld, A.M.; Lieb, K.P.

1979-01-01

Measurements of the reorientation effect for the first excited 2 + states in 200 , 202 , 204 Hg were performed by exploiting the dependence of the γ-ray yield on Q 2 + for different projectiles. For 200 Hg, a positive quadrupole moment of Q 2 = 0.96 +- 0.11 eb (for negative interference) or Q 2 = 1.11 +- 0.11 eb (for positive interference) was determined indicating an oblate shape. Small positive Q 2 values were also found for 202 Hg and 204 Hg. Nine B(E2) values for excitation of the 2 + , 2 + ' and 4 + states in 196-204 Hg were measured. (orig.) [de

Hg stable isotope analysis by the double-spike method.

Science.gov (United States)

Mead, Chris; Johnson, Thomas M

2010-06-01

Recent publications suggest great potential for analysis of Hg stable isotope abundances to elucidate sources and/or chemical processes that control the environmental impact of mercury. We have developed a new MC-ICP-MS method for analysis of mercury isotope ratios using the double-spike approach, in which a solution containing enriched (196)Hg and (204)Hg is mixed with samples and provides a means to correct for instrumental mass bias and most isotopic fractionation that may occur during sample preparation and introduction into the instrument. Large amounts of isotopic fractionation induced by sample preparation and introduction into the instrument (e.g., by batch reactors) are corrected for. This may greatly enhance various Hg pre-concentration methods by correcting for minor fractionation that may occur during preparation and removing the need to demonstrate 100% recovery. Current precision, when ratios are normalized to the daily average, is 0.06 per thousand, 0.06 per thousand, 0.05 per thousand, and 0.05 per thousand (2sigma) for (202)Hg/(198)Hg, (201)Hg/(198)Hg, (200)Hg/(198)Hg, and (199)Hg/(198)Hg, respectively. This is slightly better than previously published methods. Additionally, this precision was attained despite the presence of large amounts of other Hg isotopes (e.g., 5.0% atom percent (198)Hg) in the spike solution; substantially better precision could be achieved if purer (196)Hg were used.

A ratiometric electrochemical biosensor for sensitive detection of Hg2+ based on thymine-Hg2+-thymine structure.

Science.gov (United States)

Xiong, Erhu; Wu, Liang; Zhou, Jiawan; Yu, Peng; Zhang, Xiaohua; Chen, Jinhua

2015-01-01

In this paper, a simple, selective and reusable electrochemical biosensor for the sensitive detection of mercury ions (Hg(2+)) has been developed based on thymine (T)-rich stem-loop (hairpin) DNA probe and a dual-signaling electrochemical ratiometric strategy. The assay strategy includes both "signal-on" and "signal-off" elements. The thiolated methylene blue (MB)-modified T-rich hairpin DNA capture probe (MB-P) firstly self-assembled on the gold electrode surface via Au-S bond. In the presence of Hg(2+), the ferrocene (Fc)-labeled T-rich DNA probe (Fc-P) hybridized with MB-P via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. As a result, the hairpin MB-P was opened, the MB tags were away from the gold electrode surface and the Fc tags closed to the gold electrode surface. These conformation changes led to the decrease of the oxidation peak current of MB (IMB), accompanied with the increase of that of Fc (IFc). The logarithmic value of IFc/IMB is linear with the logarithm of Hg(2+) concentration in the range from 0.5 nM to 5000 nM, and the detection limit of 0.08 nM is much lower than 10nM (the US Environmental Protection Agency (EPA) limit of Hg(2+) in drinking water). What is more, the developed DNA-based electrochemical biosensor could be regenerated by adding cysteine and Mg(2+). This strategy provides a simple and rapid approach for the detection of Hg(2+), and has promising application in the detection of Hg(2+) in real environmental samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Interactions of Hg(ii) with oligonucleotides having thymine-thymine mispairs. Optimization of an impedimetric Hg(ii) sensor.

Science.gov (United States)

Kamal, Ajar; She, Zhe; Sharma, Renu; Kraatz, Heinz-Bernhard

2017-05-21

The present work describes the effect of the number of thymine-thymine mispairs in single strand DNA probes on Hg(ii) interactions and further to develop a highly sensitive DNA based impedimetric sensor for Hg(ii) detection. To achieve this goal, the influence of the number of T-T mispairs on the signal response prompted by DNA-Hg(ii) binding interactions was examined on three designed DNA probes: 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACACGTTCCTTACGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACATTTTCCTTTTGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCATTTTTTCCTTTTTT-3' having 2T-T, 4T-T and 6T-T mispairs with identical length, respectively. This study revealed that the number of T-T mispairs plays a critical role in maximizing the signal intensity of DNA-Hg(ii) binding interactions. Based on these results, DNA comprising maximum number of T-T mispairs was further utilized for construction of the Hg(ii) sensor, which exhibited a linear correlation between the change in charge transfer resistance (ΔR CT ) and the concentration of Hg(ii) over the range of 1.0 × 10 -5 M to 1.0 × 10 -10 M with a lower detection limit of 3.2 × 10 -11 M. The selectivity was tested against 12 different metal ions including Hg(ii). The ΔR CT response from Hg(ii) is 3 times higher than the nearest competitor Pb(ii) and approximately 10 times than other ions. The potential application of such a robust and label-free DNA sensor was demonstrated by analyzing environmental samples collected from Lake Ontario.

Assessment of Hg Pollution Released from a WWII Submarine Wreck (U-864) by Hg Isotopic Analysis of Sediments and Cancer pagurus Tissues.

Science.gov (United States)

Rua-Ibarz, Ana; Bolea-Fernandez, Eduardo; Maage, Amund; Frantzen, Sylvia; Valdersnes, Stig; Vanhaecke, Frank

2016-10-04

Hg pollution released from the U-864 submarine sunk during WWII and potential introduction of that Hg into the marine food chain have been studied by a combination of quantitative Hg and MeHg determination and Hg isotopic analysis via cold vapor generation multicollector inductively coupled plasma-mass spectrometry (CVG-MC-ICP-MS) in sediment and Cancer pagurus samples. The sediment pollution could be unequivocally linked with the metallic Hg present in the wreck. Crabs were collected at the wreck location and 4 nmi north and south, and their brown and claw meat were analyzed separately. For brown meat, the δ 202 Hg values of the individuals from the wreck location were shifted toward the isotopic signature of the sediment and, thus, the submarine Hg. Such differences were not found for claw meat. The isotope ratio results suggest direct ingestion of metallic Hg by C. pagurus but do not offer any proof for any other introduction of the submarine Hg into the marine food chain.

40 CFR 60.4111 - Alternate Hg designated representative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Alternate Hg designated representative... Times for Coal-Fired Electric Steam Generating Units Hg Designated Representative for Hg Budget Sources § 60.4111 Alternate Hg designated representative. (a) A certificate of representation under § 60.4113...

Mercury toxicokinetics-dependency on strain and gender

International Nuclear Information System (INIS)

Ekstrand, Jimmy; Nielsen, Jesper B.; Havarinasab, Said; Zalups, Rudolfs K.; Soederkvist, Peter; Hultman, Per

2010-01-01

Mercury (Hg) exposure from dental amalgam fillings and thimerosal in vaccines is not a major health hazard, but adverse health effects cannot be ruled out in a small and more susceptible part of the exposed population. Individual differences in toxicokinetics may explain susceptibility to mercury. Inbred, H-2-congenic A.SW and B10.S mice and their F1- and F2-hybrids were given HgCl 2 with 2.0 mg Hg/L drinking water and traces of 203 Hg. Whole-body retention (WBR) was monitored until steady state after 5 weeks, when the organ Hg content was assessed. Despite similar Hg intake, A.SW males attained a 20-30% significantly higher WBR and 2- to 5-fold higher total renal Hg retention/concentration than A.SW females and B10.S mice. A selective renal Hg accumulation but of lower magnitude was seen also in B10.S males compared with females. Differences in WBR and organ Hg accumulation are therefore regulated by non-H-2 genes and gender. Lymph nodes lacked the strain- and gender-dependent Hg accumulation profile of kidney, liver and spleen. After 15 days without Hg A.SW mice showed a 4-fold higher WBR and liver Hg concentration, but 11-fold higher renal Hg concentration, showing the key role for the kidneys in explaining the slower Hg elimination in A.SW mice. The trait causing higher mercury accumulation was not dominantly inherited in the F1 hybrids. F2 mice showed a large inter-individual variation in Hg accumulation, showing that multiple genetic factors influence the Hg toxicokinetics in the mouse. The genetically heterogeneous human population may therefore show a large variation in mercury toxicokinetics.

Sediment geochemistry and accumulation rates on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula

Directory of Open Access Journals (Sweden)

Roberta Guerra

2010-11-01

Full Text Available Geochemistry, total organic carbon and total nitrogen of three sediment cores collected in the Gulf of Cádiz and the Guadalquivir prodelta areas in Spain were investigated. The C/N ratio, mostly around 10, seems to indicate a predominantly marine origin for the sedimentary organic matter. Major and minor elements (Si, Ti, Al, Fe, Mg, Ca, K, Na, P, S and trace elements (Mn, Sc, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Ba, Ce, Pb, Hg showed significant differences in bulk chemical composition between the two areas. Despite the effects of bioturbation, vertical changes in downcore profiles of heavy metals occur only in the cores of the Cádiz area, although the concentrations keep to low levels. The relatively high concentrations of Zr and Y, elements commonly associated with the heavy minerals fraction, at the top of cores from the Cádiz area are attributed to an enrichment of heavy minerals related to selective transport that concentrates this fraction. 137Cs and 210Pb activities in one of the two sediment cores collected in the Gulf of Cádiz were also measured. The distribution of excess 210Pb was used to determine the modern (last 100 yr mass accumulation rate and the depth of sediment mixing on the continental shelf of the gulf. Estimated sediment accumulation rate was 0.1 g cm-2 yr-1. The uppermost 4 cm had uniform excess 210Pb activity profiles above a region of steadily decreasing 210Pb activity, and this phenomenon was attributed to sediment mixing (bioturbation. 137Cs activity was lower than 3 Bq kg-1 and the profile does not show evidence of fallout peaks.

Screening of chelating ligands to enhance mercury accumulation from historically mercury-contaminated soils for phytoextraction.

Science.gov (United States)

Wang, Jianxu; Xia, Jicheng; Feng, Xinbin

2017-01-15

ligand for phytoextraction due to its great potential to enhance Hg accumulation in plants while decreasing bioavailable Hg concentration in the soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Salt intake profile and blood pressure in cystic fibrosis].

Science.gov (United States)

Campuzano Martín, S H; Díaz Martín, J J; Perillán Méndez, C; Argüelles Luis, J; Vijande Vázquez, M; Málaga Guerrero, S

2009-05-01

High blood pressure (BP) is not considered a problem in patients with cystic fibrosis (CF). The loss of sodium in these patients may affect their sensitivity to the taste of salt. To study the BP in a group of patients with CF and to analyse their salt intake profile and the relationship with their BP levels. Cross-sectional analytical study with control group. Index group: 20 subjects, 4-30 years old with diagnosis of CF. 73 healthy subjects. Physical examination, BP measurement and specific tests to determine the salt ingestion profile. Systolic BP (SBP) and diastolic BP (DBP) values were lower in the CF group. SBP: 99.63+/-9.11mmHg vs. 111.94+/-10.71mmHg, P: 0.001. DBP: 57.84+/-7.40mmHg vs. 70.05+/-8.11mmHg, P: 0.001. When these values were adjusted for age, sex, weight and height of the participants, differences did not remain statistically significant. Values of the salt intake profile did not differ significantly between the two groups. While the control group showed a significant negative correlation between SBP and salt taste sensitivity (r: -0.341, P=0.003), this correlation was not confirmed in CF patients (r: -0.115 P=0.6). BP values and the salt intake profile values in CF patients are equivalent to the normal population values when their differences are adjusted to the potential confounding factors. There is no correlation between BP levels and salt taste sensitivity in patients with CF.

Intracellular Hg(0) Oxidation in Desulfovibrio desulfuricans ND132.

Science.gov (United States)

Wang, Yuwei; Schaefer, Jeffra K; Mishra, Bhoopesh; Yee, Nathan

2016-10-03

The disposal of elemental mercury (Hg(0)) wastes in mining and manufacturing areas has caused serious soil and groundwater contamination issues. Under anoxic conditions, certain anaerobic bacteria can oxidize dissolved elemental mercury and convert the oxidized Hg to neurotoxic methylmercury. In this study, we conducted experiments with the Hg-methylating bacterium Desulfovibrio desulfuricans ND132 to elucidate the role of cellular thiols in anaerobic Hg(0) oxidation. The concentrations of cell-surface and intracellular thiols were measured, and specific fractions of D. desulfuricans ND132 were examined for Hg(0) oxidation activity and analyzed with extended X-ray absorption fine structure (EXAFS) spectroscopy. The experimental data indicate that intracellular thiol concentrations are approximately six times higher than those of the cell wall. Cells reacted with a thiol-blocking reagent were severely impaired in Hg(0) oxidation activity. Spheroplasts lacking cell walls rapidly oxidized Hg(0) to Hg(II), while cell wall fragments exhibited low reactivity toward Hg(0). EXAFS analysis of spheroplast samples revealed that multiple different forms of Hg-thiols are produced by the Hg(0) oxidation reaction and that the local coordination environment of the oxidized Hg changes with reaction time. The results of this study indicate that Hg(0) oxidation in D. desulfuricans ND132 is an intracellular process that occurs by reaction with thiol-containing molecules.

Luminescent turn-on detection of Hg(II) via the quenching of an iridium(III) complex by Hg(II)-mediated silver nanoparticles.

Science.gov (United States)

Liu, Jinshui; Vellaisamy, Kasipandi; Yang, Guanjun; Leung, Chung-Hang; Ma, Dik-Lung

2017-06-15

A novel luminescent turn-on detection method for Hg(II) was developed. The method was based on the silver nanoparticle (AgNP)-mediated quenching of Ir(III) complex 1. The addition of Hg(II) ions causes the luminescence of complex 1 to be recovered due to the oxidation of AgNPs by Hg(II) ions to form Ag(I) and Ag/Hg amalgam. The luminescence intensity of 1 increased in accord with an increased Hg(II) concentration ranging from 0 nM to 180 nM, with the detection limit of 5 nM. This approach offers an innovative method for the quantification of Hg(II).

40 CFR 60.4160 - Submission of Hg allowance transfers.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Submission of Hg allowance transfers... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Transfers § 60.4160 Submission of Hg allowance transfers. An Hg authorized account representative seeking recordation of a Hg allowance transfer...

Hg uptake in ureteral obstructions

International Nuclear Information System (INIS)

Desgrez, J.P.; Bourguignon, M.; Raynaud, C.; CEA, 91 - Orsay

1976-01-01

In the presence of a total obstruction the results obtained with the Hg uptake test, as indeed with other functional tests, inform on the value of the kidney function at the time but have no prognostic value where repair possibilities are concerned. Some preliminary results seem to show however that very soon after the obstacle is removed, by the 10th or 15th day perhaps, quantitative functional tests may once more be used to evaluate the functional prognosis. This would mean that by waiting about two weeks after the disappearance of a total obstruction the Hg uptake test may again be used in all confidence. In order to check this deduction, which is based on slender evidence but which nevertheless has important practical implications, the measurement of the Hg uptake rate during the days following removal of the obstacle appears essential. In long-standing partial obstructions the Hg uptake rate gives an accurate assessment of the functional balance and helps considerably in the choice of therapy [fr

Fish consumption, mercury exposure, and the risk of cholesterol profiles: findings from the Korea National Health and Nutrition Examination Survey 2010-2011

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Yong Min Cho

2017-08-01

Full Text Available In this study, the associations between mercury (Hg exposure and cholesterol profiles were analyzed, and increased Hg levels and cholesterol profiles according to the amount of fish consumption were evaluated. Data on levels of blood Hg, the frequency of fish consumption, total blood cholesterol (TC, high-density lipoprotein cholesterol (HDL-C, low-density lipoprotein cholesterol (LDL-C, and triglyceride (TG in 3951 adults were obtained from the Korea National Health and Nutrition Examination Survey 2010-2011 database. To compare the distribution for each log-transformed indicator, Student’s t-test and analysis of variance were carried out, and the groups were classified according to the frequency of fish consumption through linear regression analysis; the association between Hg level and cholesterol profiles in each group was analyzed. The blood Hg levels (arithmetic mean, median, and geometric mean for all target participants were 4.59, 3.66, and 3.74 µg/L, respectively. The high cholesterol group, low HDL-C group, and high TG group showed a statistically and significantly higher blood Hg level than the low-risk group. In both sexes, as the frequency of fish consumption increased, blood Hg level also increased, but TC, HDL-C, LDL-C, and TG did not show a similar trend. Increased blood Hg level showed a significant association with increased TC and LDL-C. This statistical significance was maintained in the group with less frequent fish consumption (8 times per month did not show a similar trend. The results of this study suggest that fish consumption increases the level of Hg exposure, and that as the level of Hg exposure increases, the levels of cholesterol profiles increase. However, this study also suggests that the levels of cholesterol profiles in those with frequent fish consumption can be diminished.

Immobilization of aqueous Hg(II) by mackinawite (FeS)

International Nuclear Information System (INIS)

Liu Jianrong; Valsaraj, Kalliat T.; Devai, Istvan; DeLaune, R.D.

2008-01-01

As one of the major constituents of acid volatile sulfide (AVS) in anoxic sediments, mackinawite (FeS) is known for its ability to scavenge trace metals. The interaction between aqueous Hg(II) (added as HgCl 2 ) and synthetic FeS was studied via batch sorption experiments conducted under anaerobic conditions. Due to the release of H + during formation of hydrolyzed Hg(II) species which is more reactive than Hg 2+ in surface adsorption, the equilibrium pH decreased with the increase in Hg(II)/FeS molar ratio. Counteracting the loss of FeS solids at lower pH, the maximum capacity for FeS to remove aqueous Hg(II) was approximately 0.75 mol Hg(II) (mol FeS) -1 . The comparison of X-ray power diffraction (XRPD) patterns of synthetic FeS sorbent before and after sorption showed that the major products formed from the interaction between FeS and the aqueous Hg(II) were metacinnabar, cinnabar, and mercury iron sulfides. With the addition of FeS at 0.4 g L -1 to a 1 mM Hg(II) solution with an initial pH of 5.6, Fe 2+ release was approximately 0.77 mol Fe 2+ per mol Hg(II) removed, suggesting that 77% of Hg(II) was removed via precipitation reaction under these conditions, with 23% of Hg(II) removed by adsorption. Aeration does not cause significant release of Hg(II) into the water phase

Fractionation distribution and preliminary ecological risk assessment of As, Hg and Cd in ornithogenic sediments from the Ross Sea region, East Antarctica

Energy Technology Data Exchange (ETDEWEB)

Lou, Chuangneng [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Liu, Xiaodong, E-mail: ycx@ustc.edu.cn [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Nie, Yaguang [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Emslie, Steven D. [Department of Biology and Marine Biology, University of North Carolina Wilmington, 601S. College Road, Wilmington, NC 28403 (United States)

2015-12-15

To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. Organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation. - Highlights: • Residual As holds a dominant position in ornithogenic sediments. • Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions. • Exchangeable Cd occupies a considerable proportion in ornithogenic sediments. • TOC is the main factor controlling the mobility of Hg and Cd in studied sediments.

Injury of Hg2+ and DBS on Lemna minor%Hg2+、DBS对浮萍的伤害研究

Institute of Scientific and Technical Information of China (English)

马剑敏; 王琳; 杜晋立; 吴晶敏

2001-01-01

The injury degree of Lemna minor by the stress of Hg2+ and DBSare reported.The concentrations of chlorophyll and dissolved protein decrease with the increase of Hg2+ and DBS concentrations or as treatment time is continued,dead percentage increase with the increase of Hg2+ and DBS concentrations or as treatment time is continued.When the concentrations of HgCl2 is 6mg/L or DBS is 12mg/L,about 70% of Lemna minor can live for 10 days at least.%研究了在Hg2+、DBS胁迫下，浮萍(LemnaminorL.)植株的枯死率、叶绿素含量和可溶性蛋白质含量的变化。植株的枯死率随Hg2+、DBS浓度升高和处理时间的延长而增加；叶绿素和蛋白质含量随Hg2+和DBS浓度升高和处理时间的延长而逐渐下降。在HgCl2、DBS浓度分别为6mg/L、12mg/L时，约70%的浮萍10d内仍存活。

Fourier transform nuclear magnetic resonance studies of 199Hg

International Nuclear Information System (INIS)

Krueger, H.; Lutz, O.; Nolle, A.; Schwenk, A.

1975-01-01

199 Hg Fourier Transform NMR studies of various solutions of diverse mercury salts in H 2 O and D 2 O or in the appropriate protonated and deuterated acids are reported for both Hg 2 ++ and Hg ++ . In the different solutions investigated the 199 Hg line positions depend on the concentration of the solution, on the solvents and their isotopic composition and on the temperature of the sample. A ratio of the Larmor frequency of 199 Hg and of 2 H in a Hg(NO 3 ) 2 solution in dilute DNO 3 is given. Using this ratio and the measured chemical shifts, a ratio of the Larmor frequencies of 199 Hg for infinite dilution relative to 2 H in pure D 2 O is given. From this a g 1 -factor for 199 Hg is derived and compared with the g 1 -factor of an optical pumping experiment. The resulting shielding constant is sigma (hydrated 199 Hg ++ versus 199 Hg atom) = -24.32(5) x 10 -4 . This yields an atomic reference scale for all measured NMR line shifts of mercury. (orig.) [de

Meteorological effects on Hg wet deposition in a forested site in the Adirondack region of New York during 2000-2015

Science.gov (United States)

Mao, Huiting; Ye, Zhuyun; Driscoll, Charles

2017-11-01

An analysis of weekly measurement data of mercury (Hg) wet deposition was conducted for Huntington Wildlife Forest (HWF), a forest ecosystem in Upstate New York and a biological Hg hotspot, during 2000-2015. Annual accumulated Hg wet deposition flux was found to decrease at a rate of -0.13 μg m-2 yr-1 (2% yr-1) (p = 0.09), and volume weighted mean (VWM) Hg precipitation concentrations at -0.14 ng L-1 yr-1 (2.5% yr-1) (p = 0.00). In examining data by season, no trends were identified for the two variables. It was found that the North Atlantic Oscillation (NAO) affected Hg wet deposition predominantly in spring, as did the position of the U.S. East Coast trough in summer, which suggests different dominant mechanisms driving Hg wet deposition in different seasons. The impacts of such large scale circulation processes were facilitated via variations in precipitation amounts. This was manifested in spring 2011 with the strongest positive phase of NAO, resulting in the wettest spring with the largest Hg wet deposition flux, and in summer 2007 with the U.S. East Coast trough positioned the farthest out over the Atlantic Ocean, causing the driest summer with the lowest Hg wet deposition flux of the study period. Extreme precipitation amounts in spring could singularly drive the overall long-term trend in Hg wet deposition whereas in summer other factors could just be as important. Similar mechanisms were thought to control the long term variations of Hg wet deposition and precipitation concentrations in all seasons but summer as indicated in their significant correlation in all but summer. Atmospheric concentrations of gaseous oxidized mercury (GOM) and particulate borne mercury (PBM) at HWF over 2009-2015 hardly exhibited correlations with Hg wet deposition or precipitation concentrations. Chemical transport model simulations strongly supported efficient scavenging of oxidized Hg by precipitation resulting in the lowest concentration of GOM in the warm season despite the

Specific accumulation of 20 trace elements in great cormorants (Phalacrocorax carbo) from Japan

International Nuclear Information System (INIS)

Nam, Dong-Ha; Anan, Yasumi; Ikemoto, Tokutaka; Okabe, Yuko; Kim, Eun-Young; Subramanian, Annamalai; Saeki, Kazutoshi; Tanabe, Shinsuke

2005-01-01

This study is to elucidate the specific accumulation of 20 trace elements in tissues/organs of great cormorants from two different colonies (Lake Biwa and Mie) in Japan. In the body distribution of trace elements, some elements revealed tissue-specific accumulation such as most of the burden of Mo, Ag and Cd in liver, Tl and Cd in kidney, Cu, Rb and Cs in muscle, and V, Sr and Ba in bone. Gender-related variation was not observed in both populations for most of the trace elements, except for higher hepatic Sr in males from Lake Biwa. Hepatic V, muscular Hg and Tl, and Cd in liver, kidney and muscle increased with growth. Comparison of trace element levels in tissues between the two colonies showed that Cr, Rb, Sr, Cd, Cs, Ba and Tl levels were higher in Lake Biwa than in Mie, whereas Zn, Co and Hg in Mie samples were greater than Lake Biwa. Variations of elemental levels in stomach contents also showed similar patterns, thus, showing that dietary sources tended to be the main factor for these regional variations. Toxic Hg and Cd concentrations in the liver of cormorants from the two colonies were lower than those from other areas, implying relatively low exposure to these metals in the present study sites. Concentrations of V, Co, Ag, Cd, Cs, Hg, Tl, Pb and Bi in liver remained more or less at the same level between 1993 and 2003, while hepatic Cr, Mn, Cu, Zn, Se, Rb, Sr and Ba showed apparent decrease, which might be related to the biological factors. - Dietary sources seemed to be the main reason for variable results

Design and synthesis of BODIPY-clickate based Hg(2+) sensors: the effect of triazole binding mode with Hg(2+) on signal transduction.

Science.gov (United States)

Vedamalai, Mani; Kedaria, Dhaval; Vasita, Rajesh; Mori, Shigeki; Gupta, Iti

2016-02-14

BODIPY-clickates, F1 and F2, for the detection of Hg(2+) have been designed, synthesized and characterized. Both F1 and F2 showed hyperchromic shifts in the UV-visible spectra in response to increasing Hg(2+) concentrations. Hg(2+) ion binding caused perturbation of the emission quenching process and chelation induced enhanced bathochromic emission of F1 and F2 to 620 nm and 660 nm, respectively. Job's plot clearly indicated that the binding ratio of F1 and F2 with Hg(2+) was 1 : 1. The NMR titration of BODIPY-clickates with Hg(2+) confirmed that aromatic amines and triazoles were involved in the binding event. Furthermore, HRMS data of F1-Hg(2+) and F2-Hg(2+) supported the formation of mercury complexes of BODIPY-clickates. The dissociation constant for the interaction between fluorescent probes F1 and F2 with Hg(2+) was found to be 24.4 ± 5.1 μM and 22.0 ± 3.9 μM, respectively. The Hg(2+) ion induced fluorescence enhancement was almost stable in a pH range of 5 to 8. Having less toxicity to live cells, both the probes were successfully used to map the Hg(2+) ions in live A549 cells.

[Spatial distribution and ecological significance of heavy metals in soils from Chatian mercury mining deposit, western Hunan province].

Science.gov (United States)

Sun, Hong-Fei; Li, Yong-Hu; Ji, Yan-Fang; Yang, Lin-Sheng; Wang, Wu-Yi

2009-04-15

Ores, waste tailings and slag, together with three typical soil profiles (natural soil profiles far from mine entrance and near mine entrance, soil profile under slag) in Chatian mercury mining deposit (CMD), western Hunan province were sampled and their concentrations of mercury (Hg), arsenic (As), lead (Pb), cadmium (Cd), zinc (Zn) were determined by HG-ICP-AES and ICP-MS. Enrichment factor and correlation analysis were taken to investigate the origins, distribution and migration of Hg, as well as other heavy metals in the CMD. The results show that Hg is enriched in the bottom of the soil profile far from mine entrance but accumulated in the surface of soil profiles near mine entrance and under slag. The soil profiles near mine entrance and under slag are both contaminated by Hg, while the latter is contaminated more heavily. In the soil profile under slag, Hg concentration in the surface soil, Hg average concentration in the total profile, and the leaching depth of soil Hg are 640 microg x g(-1), (76.74 +/- 171.71) microg x g(-1), and more than 100 cm, respectively; while 6.5 microg x g(-1), (2.74 +/- 1.90) microg x g(-1), and 40 cm, respectively, are found in the soil profile near mine entrance. Soil in the mercury mine area is also polluted by Cd, As, Pb, Zn besides metallogenic element Hg, among which Cd pollution is relatively heavier than others. The mobility of the studied heavy metals in soil follows the order as Hg > Cd > As > Zn approximately equal to Pb. The leaching depth of the heavy metals is influenced by total concentration in the surface soil and soil physico-chemical parameters. The origins, distribution and migration of heavy metals in soil profile in the mining area are related to primary geological environment, and strongly influenced by human mining activities.

Carbon-13 isotope effects on 199Hg nuclear shielding

International Nuclear Information System (INIS)

Sebald, Angelika; Wrackmeyer, Bernd

1985-01-01

Secondary 13 C/ 12 C isotope effects on 199 Hg nuclear shielding (Δdeltasup(i)( 199 Hg)) are of interest because of the unusual shift to high frequency which has been observed for a few alkyl mercury compounds. Continuing interest in the NMR parameters of mercury compounds prompted a search for the values Δdeltasup(i)( 199 Hg) in a greater variety of organomercurials. This should help to find out about the range of Δdeltasup(i)( 199 Hg) and to obtain a firmer basis for the discussion of the high-frequency shifts. The data and experimental conditions are given for chemical shifts delta 199 Hg, coupling constants sup(n)J( 199 Hg 13 C) and 13 C/ 12 C isotope shifts Δdeltasup(i)( 199 Hg) of fourteen 199 Hg organomercury compounds. The results are discussed. (author)

Environmental impact of CO2, Rn, Hg degassing from the rupture zones produced by Wenchuan M s 8.0 earthquake in western Sichuan, China.

Science.gov (United States)

Zhou, Xiaocheng; Chen, Zhi; Cui, Yueju

2016-10-01

The concentrations and flux of CO2, (222)Radon (Rn), and gaseous elemental mercury (Hg) in soil gas were investigated based on the field measurements in June 2010 at ten sites along the seismic rupture zones produced by the May 12, 2008, Wenchuan M s 8.0 earthquake in order to assess the environmental impact of degassing of CO2, Rn and Hg. Soil gas concentrations of 344 sampling points were obtained. Seventy measurements of CO2, Rn and Hg flux by the static accumulation chamber method were performed. The results of risk assessment of CO2, Rn and Hg concentration in soil gas showed that (1) the concentration of CO2 in the epicenter of Wenchuan M s 8.0 earthquake and north end of seismic ruptures had low risk of asphyxia; (2) the concentrations of Rn in the north segment of seismic ruptures had high levels of radon, Maximum was up to level 4, according to Chinese code (GB 50325-2001); (3) the average geoaccumulation index I geo of soil Hg denoted the lack of soil contamination, and maximum values classified the soil gas as moderately to strongly polluted in the epicenter. The investigation of soil gas CO2, Rn and Hg degassing rate indicated that (1) the CO2 in soil gas was characterized by a mean [Formula: see text] of -20.4 ‰ and by a mean CO2 flux of 88.1 g m(-2) day(-1), which were in the range of the typical values for biologic CO2 degassing. The maximum of soil CO2 flux reached values of 399 g m(-2) day(-1) in the epicenter; (2) the soil Rn had higher exhalation in the north segment of seismic ruptures, the maximum reached value of 1976 m Bq m(-2) s(-1); (3) the soil Hg flux was lower, ranging from -2.5 to 18.7 n g m(-2) h(-1) and increased from south to north. The mean flux over the all profiles was 4.2 n g m(-2) h(-1). The total output of CO2 and Hg degassing estimated along seismic ruptures for a survey area of 18.17 km(2) were approximately 0.57 Mt year(-1) and 688.19 g year(-1). It is recommended that land-use planners should

Influence of defect structure on magnetic and electronic properties of Hg1-x Crx Se and Hg1-x Cox Se

International Nuclear Information System (INIS)

Prozorovskij, V.D.; Reshidova, I.Yu.; Puzynya, A.I.; Paranchich, Yu.S.

1996-01-01

The results of experimental investigations of the Shubnikov-de Haas oscillations at superhigh frequencies, electron spin resonance, magnetic susceptibility, relaxation dielectric losses, and galvanomagnetic measurements in the Hg 1-x Cr x Se and Hg 1-x Co x Se single crystal samples are presented. Analysis of the results Hg 1-x Cr x Se and Hg 1-x Co x Se depend on the defect structure of the substance and the type of defects making this structure. The manifestation of critical phenomena in Hg 1-x Cr x Se also depends on the defect structure

40 CFR 60.4114 - Objections concerning Hg designated representative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Objections concerning Hg designated... Times for Coal-Fired Electric Steam Generating Units Hg Designated Representative for Hg Budget Sources § 60.4114 Objections concerning Hg designated representative. (a) Once a complete certificate of...

Problems with the dating of sediment core using excess 210Pb in a freshwater system impacted by large scale watershed changes

International Nuclear Information System (INIS)

Baskaran, Mark; Nix, Joe; Kuyper, Clark; Karunakara, N.

2014-01-01

Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess 210 Pb ( 210 Pb xs ) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess 210 Pb and 137 Cs. There is no decrease in excess 210 Pb activity with depth while the 137 Cs profile indicates sharp peak corresponding to 1963 and the 137 Cs penetration depth of 137 Cs corresponds to 1952. The historical data on the accelerated mercury mining during 1931–1944 resulted in large-scale Hg input to this watershed. Using the peak Hg activity as a time marker, the obtained sediment accumulation rates agree well with the 137 Cs-based rates. Four independent evidences (two-marker events based on 137 Cs and two marker events based on Hg mining activity) result in about the same sedimentation rates and thus, we endorse earlier suggestion that 210 Pb profile always needs to be validated with at least one another independent method. We also present a concise discussion on what important factors that can affect the vertical profiles of 210 Pb xs in relatively smaller lakes

Uptake and clearance of mercury Hg (NO3)2-203Hg by the guppy (Lebistes reticulatus)

International Nuclear Information System (INIS)

Ferreira, J.R.; Rodrigues, N.S.; Nascimento Filho, V.F. do

1982-01-01

Fishes weighing between 20.6 and 536.9 mg were exposed to 25, 50 and 100 μg Hg.l -1 as Hg (NO 3 ) 2 labelled with 203 Hg, for 17 days in plastic aquaria containing 4 litre of soft aerated dechlorinated water. Whole body mercury contents were determined periodically by gamma counting, using a single channel spectrometer and a 3 in X 3 in NaI(Tl) well crystal. The highest bioconcentration of mercury was after 100 h of exposure for all the treatments. A further study on the clearance of mercury nitrate was carried out by transfering fishes to mercury-free water, after a period of 100 h of exposure in solutions of 35 and μg Hg.l -1 . The fishes were not sacrificed after the dose measurment, being returned to the aquaria for further sampling. The rate of clearance was similar for both concentrations. After 120 h exposure to uncontamined water, the fishes excreted the mercury previously absorbed. The correlation coefficient of the experimentals equations were 0.91 and 0.94, respectively, for the treatments 35 and 70 μg Hg.l -1 . Both experiments, uptake and clearance were made at same values of the water physico-chemical parameters (hardness = 36 mg CaCO 3 ; pH=7.2; O.D.=7.0 mg/l; temperature=23 +- 1 0 C). (Author) [pt

The new barium zinc mercurides Ba3ZnHg10 and BaZn0.6Hg3.4 – Synthesis, crystal and electronic structure

International Nuclear Information System (INIS)

Schwarz, Michael; Wendorff, Marco; Röhr, Caroline

2012-01-01

The title compounds Ba 3 ZnHg 10 and BaZn 0.6 Hg 3.4 were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures, which both represent new structure types, have been determined using single crystal X-ray data. The structure of Ba 3 ZnHg 10 (orthorhombic, oP28, space group Pmmn, a=701.2(3), b=1706.9(8), c=627.3(3)pm, Z=2, R1=0.0657) contains folded 4 4 Hg nets, where the meshes form the bases of flat rectangular pyramids resembling the structure of BaAl 4 . The flat pyramids are connected via Hg–Zn/Hg bonds, leaving large channels at the folds, in which Ba(1) and Hg(2) atoms alternate. Whereas the remaining Hg/Zn atoms form a covalent 3D network of three- to five-bonded atoms with short M–M distances (273–301 pm; CN 9–11), the Hg(2) atoms in the channels adopt a comparatively large coordination number of 12 and increased distances (317–348 pm) to their Zn/Hg neighbours. In the structure of BaZn 0.6 Hg 3.4 (cubic, cI320, space group I4 ¯ 3d, a=2025.50(7) pm, Z=64, R1=0.0440), with a chemical composition not much different from that of Ba 3 ZnHg 10 , the Zn/Hg atoms of the mixed positions M(1/2) are arranged in an slightly distorted primitive cubic lattice with a 4×4×4 subcell relation to the unit cell. The 24 of the originating 64 cubes contain planar cis tetramers Hg(5,6) 4 with Hg in a nearly trigonal planar or tetrahedral coordination. In another 24 of the small cubes, two opposing faces are decorated by Hg(3,4) 2 dumbbells, two by Ba(2) atoms respectively. The third type of small cubes are centered by Ba(1) atoms only. The complex 3D polyanionic Hg/Zn network thus formed is compared with the Hg partial structure in Rb 3 Hg 20 applying a group-subgroup relation. Despite their different overall structures, the connectivity of the negatively charged Hg atoms, the rather metallic Zn bonding characteristic (as obtained from FP-LAPW band structure calculations) and the coordination number of 16 for all Ba cations

Ab initio study of structural, electronic and optical properties of MnHg(SCN){sub 4} and FeHg(SCN){sub 4}

Energy Technology Data Exchange (ETDEWEB)

He, K.H. [College of Maths and Physics, China University of Geosciences, Wuhan 430074 (China)]. E-mail: he23981006@126.com; Zheng, G. [College of Maths and Physics, China University of Geosciences, Wuhan 430074 (China)]. E-mail: gzheng25@yahoo.com; Chen, G. [College of Maths and Physics, China University of Geosciences, Wuhan 430074 (China); Lue, T. [College of Maths and Physics, China University of Geosciences, Wuhan 430074 (China); Wan, M. [College of Maths and Physics, China University of Geosciences, Wuhan 430074 (China); Ji, G.F. [Laboratory for Shock Wave and Detonation Physics, China Academy of Engineering Physics, Mianyang 621900 (China)

2007-03-01

The structural, electronic and optical properties of MnHg(SCN){sub 4} and FeHg(SCN){sub 4} were studied by means of quantum-mechanical calculations based on the density-functional theory and pseudopotential method. The lattice constants can be compared with the experimental values when the effects of temperature are considered. The peaks of partial density of states of S, C, N and Hg of FeHg(SCN){sub 4} have a tendency of shifting to the higher energy levels relative to those of MnHg(SCN){sub 4}. The distributions of the 3d electronic states in the transition metal atoms show quite large difference and decide different optical properties. We found that absorptional peaks of FeHg(SCN){sub 4} lag behind those of MnHg(SCN){sub 4} and the peak in the infrared range has a higher absorptional intensity, which are in accord with the experimental results. By analyzing the distributions and transitions of the 3d electronic states, we explained the different absorption phenomena.

Hg Storage and Mobility in Tundra Soils of Northern Alaska

Science.gov (United States)

Olson, C.; Obrist, D.

2017-12-01

Atmospheric mercury (Hg) can be transported over long distances to remote regions such as the Arctic where it can then deposit and temporarily be stored in soils. This research aims to improve the understanding of terrestrial Hg storage and mobility in the arctic tundra, a large receptor area for atmospheric deposition and a major source of Hg to the Arctic Ocean. We aim to characterize spatial Hg pool sizes across various tundra sites and to quantify the mobility of Hg from thawing tundra soils using laboratory mobility experiments. Active layer and permafrost soil samples were collected in the summer of 2014 and 2015 at the Toolik Field Station in northern Alaska (68° 38' N) and along a 200 km transect extending from Toolik to the Arctic Ocean. Soil samples were analyzed for total Hg concentration, bulk density, and major and trace elements. Hg pool sizes were estimated by scaling up Hg soil concentrations using soil bulk density measurements. Mobility of Hg in tundra soils was quantified by shaking soil samples with ultrapure Milli-Q® water as an extracting solution for 24 and 72 hours. Additionally, meltwater samples were collected for analysis when present. The extracted supernatant was analyzed for total Hg, dissolved organic carbon, cations and anions, redox, and ph. Mobility of Hg from soil was calculated using Hg concentrations determined in solid soil samples and in supernatant of soil solution samples. Results of this study show Hg levels in tundra mineral soils that are 2-5 times higher than those observed at temperate sites closer to pollution sources. Most of the soil Hg was located in mineral horizons where Hg mass accounted for 72% of the total soil pool. Soil Hg pool sizes across the tundra sites were highly variable (166 - 1,365 g ha-1; avg. 419 g ha-1) due to the heterogeneity in soil type, bulk density, depth to frozen layer, and soil Hg concentration. Preliminary results from the laboratory experiment show higher mobility of Hg in mineral

Immobilization of Hg(II) by Coprecipitation in Sulfate-Cement Systems

Science.gov (United States)

2012-01-01

Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in coprecipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite were the main products in Hg–Fe precipitates. Characterization of Hg–Al solids by bulk Hg EXAFS, electron microprobe, and microfocused-XRF mapping indicated coordination of Hg by Cl ligands, multiple Hg and Cl backscattering atoms, and concentration of Hg as small particles. Thermodynamic predictions agreed with experimental observations for bulk phases, but Hg speciation indicated lack of equilibration with the final solution. Results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt in ettringite as the primary immobilization mechanism. In Hg–Fe solids, structural characterization indicated Hg coordination by O atoms only and Fe backscattering atoms that is consistent with inner-sphere complexation of Hg(OH)20 coprecipitated with ferrihydrite. Precipitation of ferrihydrite removed Hg from solution, but the resulting solid was sufficiently hydrated to allow equilibration of sorbed Hg species with the aqueous solution. Electron microprobe XRF characterization of sorption samples with low Hg concentration reacted with cement and FeSO4 amendment indicated correlation of Hg and Fe, supporting the interpretation of Hg removal by precipitation of an Fe(III) oxide phase. PMID:22594782

The Hg region: Superdeformation and other shapes

International Nuclear Information System (INIS)

Janssens, R.V.F.; Carpenter, M.P.; Fernandez, P.B.; Moore, E.F.; Ahmad, I.; Khoo, T.L.; Wolfs, F.L.H.; Drigert, M.W.; Ye, D.; Beard, K.B.; Reviol, W.; Bearden, I.; Benet, P.; Daly, P.J.; Grabowski, Z.W.

1990-01-01

We shall first summarize the present experimental situation concerning 192 Hg, the nucleus regarded as the analog of 152 Dy 8 for this SD region in that shell gaps are calculated 5 to occur at large deformation for Z=80 and N=112. Proton and neutron excitations out of te 192 Hg core will then be reviewed with particular emphasis on 191 Hg and 193 Tl. The implications of the results for pairing at large deformations and the need to consider other degrees of freedom (such as octupole correlations) will be addressed. The presentation will conclude with a brief discussion on other shapes seen in this region, with a particular emphasis on 191 Hg

40 CFR 60.4153 - Recordation of Hg allowance allocations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Recordation of Hg allowance allocations... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Tracking System § 60.4153 Recordation of Hg allowance allocations. (a) By December 1, 2006, the Administrator will record in the Hg Budget...

Heavy metals (As, Hg and V) and stable isotope ratios (δ13C and δ15N) in fish from Yellow River Estuary, China.

Science.gov (United States)

Liu, Yuan; Liu, Guijian; Yuan, Zijiao; Liu, Houqi; Lam, Paul K S

2018-02-01

The Yellow River Estuary is a significant fishery, but at present there are few studies about the concentrations of arsenic (As), mercury (Hg) and vanadium (V) in fish from this area, which might cause potential health risk to fish consumers. The aim of this study was to research on the accumulation and potential sources of heavy metals in the fish of the Yellow River Estuary. Arsenic, Hg, V and stable isotope ratios (δ 15 N and δ 13 C) in 11 species of 129 fish were analyzed. Results showed that the concentrations of As and Hg were all lower than the guideline levels established by international organizations and legal limits by several countries. The mean concentrations of V in samples in this study were significantly higher than the results of previous studies on other regions. Arsenic, Hg and V significantly differed across species (PHg, which could be explained by the positive correlation between Hg concentrations and δ 15 N in fish. Through estimation of daily intake of inorganic As (iAs), Hg and V via fish consumption, the heavy metal contamination level of fish samples fell in an acceptable range, indicating no potentially hazardous for human health. Copyright © 2017 Elsevier B.V. All rights reserved.

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

Science.gov (United States)

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

2002-01-01

Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

Estudo eletroquímico e termoanalítico dos sistemas Ir/Hg e Pt - (30%) Ir/Hg

OpenAIRE

Milaré, Edilson [UNESP

2004-01-01

Eletrodos laminares de Ir ou Pt-Ir(30%) foram empregados como substratos para deposição eletroquímica de Hg, a partir de soluções contendo íons Hg(I), e remoção deste Hg por meio de voltametria cíclica (VC) ou térmica (termogravimetria / termogravimetria derivada - TG/DTG e calorimetria exploratória diferencial - DSC). A superfície dos eletrodos foi caracterizada empregando-se as técnicas complementares de análise: microscopia eletrônica de varredura (imagens SEM, microanálise por EDX e mapas...

40 CFR 60.45Da - Standard for mercury (Hg).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for mercury (Hg). 60.45Da... for mercury (Hg). (a) For each coal-fired electric utility steam generating unit other than an IGCC... gases that contain mercury (Hg) emissions in excess of each Hg emissions limit in paragraphs (a)(1...

Radiotoxicological properties of neohydrin, labelled with Hg/sup 197/,/sup 203/ in quantities used for diagnostic purposes

Energy Technology Data Exchange (ETDEWEB)

Karklinskaya, O N [Tsentral' nyj Inst. Usovershenstvovaniya Vrachej, Moscow (USSR)

1975-07-01

Experiments on rats showed that the chief place of accumulation of mercury isotopes is the kidney (specific activity in the kidneys was 25 to 30 times that in other organs). Doses due to labelled Neohydrin in kidney tissue, calculated by generally accepted formulas were: 20.1 rad for Neohydrin-Hg/sup 203/ and 0.08 rad for Neohydrin-Hg/sup 197/. Histological studies did not indicate any morphological changes in the kidneys. However, nonhomogeneous, focal granular dystrophy was noted, and in some places, vacuolar dystrophy. In the descending portion of the distal canals and the Henle lemniscus there was an expansion of the lumen, with places of heavy thickening of the epithelium. An unequal plethora of vessels, sometimes with small hemorrhages and of edema, was observed. Specific reactions to mercury were negative. Morphological studies did not show any blood changes.

Simple and green synthesis of piperazine-grafted reduced graphene oxide and its application for the detection of Hg(II)

Science.gov (United States)

Zuo, Yinxiu; Xu, Jingkun; Xing, Huakun; Duan, Xuemin; Lu, Limin; Ye, Guo; Jia, Haiyan; Yu, Yongfang

2018-04-01

In this paper, piperazine-grafted reduced graphene oxide (NH-rGO) was synthesized via a simple and green two-step procedure: (i) opening of the resulting epoxides of graphene oxide (GO) with piperazine (NH) through nucleophilic substitution; (ii) reduction of GO with ascorbic acid. Its structure and morphology were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy. The NH-rGO modified glassy carbon electrode was explored as an electrochemical sensor for the determination of Hg(II) using a differential pulse anodic stripping voltammetry technique. Hg(II) can be efficiently accumulated and deposited on the surface of a modified electrode by strong coordination chemical bonds formed between Hg(II) and NH. And then the anodic stripping current can be significantly enhanced by rGO with the merits of large specific surface area and high conductivity, which served as a signal amplifier, finally realizing the highly sensitive determination of Hg(II). The experimental parameters including the pH value of the acetate buffer, deposition potential and deposition time were optimized. Under optimal conditions, the developed sensor exhibited a wide linear range from 0.4-12 000 nM with a low limit of detection of 0.2 nM, which is well below the guideline value in drinking water set by the WHO. Moreover, the practical application of this method was confirmed by an assay of Hg(II) in tap water samples with acceptable results.

A fluorescent DNA based probe for Hg(II) based on thymine-Hg(II)-thymine interaction and enrichment via magnetized graphene oxide.

Science.gov (United States)

Li, Meng-Ke; Hu, Liu-Yin; Niu, Cheng-Gang; Huang, Da-Wei; Zeng, Guang-Ming

2018-03-03

The authors describe a fluorometric assay for the determination of Hg(II). A naphthalimide derivative is used as a label for a thymine (T) rich ssDNA, and graphene oxide magnetized with Fe 3 O 4 nanoparticles acts as a quencher and preconcentrators. In the absence of Hg(II), the labeled ssDNA does not separate from the magnetized graphene oxide. As a result, fluorescence is fully quenched. In the presence of Hg(II), a T-Hg(II)-T link is formed dues to the highly affinity between T and Hg(II). Hence, fluorescence is restored. The assay has a linear response in the 1.0 to 10.0 nM Hg(II) concentration range, and a 0.65 nM detection limit. The method is selective and sensitive. It was applied to the analysis of spiked environmental water samples, and data agreed well with those obtained by atomic fluorescence spectrometry. Graphical abstract Strategy of a fluorescent probe for detecting Hg(II). The method has a 0.65 nM detection limit and is selective. MGO: magnetized graphene oxide, AHN: a fluorescent derivative of naphthalimide.

The simplest representative of a complex series. The Hg-rich amalgam Yb_1_1Hg_5_4

International Nuclear Information System (INIS)

Tambornino, Frank; Hoch, Constantin

2017-01-01

Yb_1_1Hg_5_4 is a new member of a series of amalgams with composition close to MHg_5. Its crystal structure was solved and refined on the basis of single crystal data. The structure model was confirmed with a Rietveld refinement. Yb_1_1Hg_5_4 has the first crystal structure in this family in which no disorder effects such as mixed occupation, split positions or superstructure formation is observed. It therefore can be regarded as a parent structure for all other amalgams. The crystal structure of Yb_1_1Hg_5_4 can be derived from the Gd_1_4Ag_5_1 structure type, the aristotype of this family. We give a detailed crystal structure description for Yb_1_1Hg_5_4 and discuss it in the context of the further known crystal structures closely related. A ranking within this structure family can be established by calculating features for the structural complexity for all structures, including the individual disorder phenomena.

46 CFR 53.01-5 - Scope (modifies HG-100).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Scope (modifies HG-100). 53.01-5 Section 53.01-5... General Requirements § 53.01-5 Scope (modifies HG-100). (a) The regulations in this part apply to steam... governing various types of pressure vessels and boilers. (b) Modifies HG-100. The requirements of Part HG of...

Peculiarity of electron optical orientation in Hg1-xMnxTe and Hg1-xCdxTe alloys

International Nuclear Information System (INIS)

Georgitseh, E.I.; Ivanov-Omskij, V.I.; Pogorletskij, V.M.

1991-01-01

To clarify the effect of exchange interaction of electrons with manganese ions on electron spin relaxation, a study was made on optical orientation in Hg 1-x Mn x Te alloy and Hg 1-x Cd x Te alloys with similar parameters of energy spectrum at 4.2 K. It is shown that exchange interaction in semimagnetic Hg 1-x Mn x Te solutions, caused by the presence of manganese ions, reduced the time of spin relaxation. However, this reduction is not sufficient make optical orientation of electrons not observable

40 CFR 60.4124 - Hg budget permit revisions.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Hg budget permit revisions. 60.4124... Coal-Fired Electric Steam Generating Units Permits § 60.4124 Hg budget permit revisions. Except as provided in § 60.4123(b), the permitting authority will revise the Hg Budget permit, as necessary, in...

Mercury(II) and methylmercury(II) complexes of novel sterically hindered thiolates: 13C and 199Hg NMR studies and the crystal and molecular structures of [MeHg(SC6H2-2,4,6-Pri3)], [Hg(SC6H4-2-SiMe3)2], [Hg(2-SC5H3N-3-SiMe3)2], and [Hg{(2-SC6H4)2SiMe2}]2

International Nuclear Information System (INIS)

Block, E.; Brito, M.; Gernon, M.; McGowty, D.; Kang, Hyunkyu; Zubieta, J.

1990-01-01

Several series of complexes of the types [MeHg(SR)] and [Hg(SR) 2 ] have been synthesized, where the ligands are members of new classes of sterically hindered thiolates, including (triorganosilyl)methanethiols, 2-(triorganosilyl)benzenethiols, 3-(triorganosilyl)pyridine-2-thiols, and bis(2-mercaptophenyl) derivatives. Detailed 1 H, 13 C, and 199 Hg NMR studies revealed several general trends. The 199 Hg chemical shifts moved upfield in the order [MeHg(SR)] 2 ] 2 ] 2 ]. For the [MeHg(SR)] series of complexes, 1 J(Hg-C) correlates with δ( 13 C(methyl)) and with the type of thiolate ligand. Anomalous behavior is observed for oligomeric species. There is only a limited correlation of δ( 199 Hg) with steric cone angles for a subset of the complexes. Crystal data for the complexes are reported. 86 refs., 7 figs., 11 tabs

Hg+ ion density in low-pressure Ar-Hg discharge plasma used for liquid crystal display back-lighting

International Nuclear Information System (INIS)

Goto, Miki; Arai, Toshihiko

1995-01-01

The positive column of a low-pressure Ar-Hg discharge has been applied as a fluorescent light source for illumination. Many studies on the diagnostics and fundamental mechanisms have been carried out on both the classical fluorescent lamp (d=36 mm) and the compact fluorescent lamp (d=12 mm). On the other hand, a lamp of extremely narrow diameter (usually below 6 mm) has been recently developed for liquid crystal display (LCD) back-lighting and its importance is undoubtedly increasing. Some characteristics or mechanisms of the narrow-diameter lamp may be similar to those of the 36 mm one; however the similarity rule does not hold between them due to the contributions from a stepwise ionization process. Therefore, in order to clarify the excitation mechanism in the narrow-diameter lamp quantitatively, various parameters must be measured directly and some analysis must be done. The Hg + ion density and electron density are important parameters for the purpose of clarifying the excitation mechanism quantitatively. In this work, we have measured the Hg + ion density using the modified absorption method, and the electron density using the probe method in the Ar-Hg discharge of the 4 mm bore tube on bath temperature. Moreover, with combining the modified absorption method and the probe method, the Hg 2 + molecular ion density has been determined

The Malus domestica sugar transporter gene family: identifications based on genome and expression profiling related to the accumulation of fruit sugars.

Science.gov (United States)

Wei, Xiaoyu; Liu, Fengli; Chen, Cheng; Ma, Fengwang; Li, Mingjun

2014-01-01

In plants, sugar transporters are involved not only in long-distance transport, but also in sugar accumulations in sink cells. To identify members of sugar transporter gene families and to analyze their function in fruit sugar accumulation, we conducted a phylogenetic analysis of the Malus domestica genome. Expression profiling was performed with shoot tips, mature leaves, and developed fruit of "Gala" apple. Genes for sugar alcohol [including 17 sorbitol transporters (SOTs)], sucrose, and monosaccharide transporters, plus SWEET genes, were selected as candidates in 31, 9, 50, and 27 loci, respectively, of the genome. The monosaccharide transporter family appears to include five subfamilies (30 MdHTs, 8 MdEDR6s, 5 MdTMTs, 3 MdvGTs, and 4 MdpGLTs). Phylogenetic analysis of the protein sequences indicated that orthologs exist among Malus, Vitis, and Arabidopsis. Investigations of transcripts revealed that 68 candidate transporters are expressed in apple, albeit to different extents. Here, we discuss their possible roles based on the relationship between their levels of expression and sugar concentrations. The high accumulation of fructose in apple fruit is possibly linked to the coordination and cooperation between MdTMT1/2 and MdEDR6. By contrast, these fruits show low MdSWEET4.1 expression and a high flux of fructose produced from sorbitol. Our study provides an exhaustive survey of sugar transporter genes and demonstrates that sugar transporter gene families in M. domestica are comparable to those in other species. Expression profiling of these transporters will likely contribute to improving our understanding of their physiological functions in fruit formation and the development of sweetness properties.

The Malus domestica sugar transporter gene family: identifications based on genome and expression profiling related to the accumulation of fruit sugars

Directory of Open Access Journals (Sweden)

Xiaoyu eWei

2014-11-01

Full Text Available In plants, sugar transporters are involved not only in long-distance transport, but also in sugar accumulations in sink cells. To identify members of sugar transporter gene families and to analyze their function in fruit sugar accumulation, we conducted a phylogenetic analysis of the Malus domestica genome. Expression profiling was performed with shoot tips, mature leaves, and developed fruit of ‘Gala’ apple. Genes for sugar alcohol (including 17 sorbitol transporters, sucrose, and monosaccharide transporters, plus SWEET genes, were selected as candidates in 31, 9, 50, and 27 loci, respectively, of the genome. The monosaccharide transporter family appears to include five subfamilies (30 MdHTs, 8 MdEDR6s, 5 MdTMTs, 3 MdvGTs, and 4 MdpGLTs. Phylogenetic analysis of the protein sequences indicated that orthologs exist among Malus, Vitis, and Arabidopsis. Investigations of transcripts revealed that 68 candidate transporters are expressed in apple, albeit to different extents. Here, we discuss their possible roles based on the relationship between their levels of expression and sugar concentrations. The high accumulation of fructose in apple fruit is possibly linked to the coordination and cooperation between MdTMT1/2 and MdEDR6. By contrast, these fruits show low MdSWEET4.1 expression and a high flux of fructose produced from sorbitol. Our study provides an exhaustive survey of sugar transporter genes and demonstrates that sugar transporter gene families in M. domestica are comparable to those in other species. Expression profiling of these transporters will likely contribute to improving our understanding of their physiological functions in fruit formation and the development of sweetness properties.

Intense charge transfer surface based on graphene and thymine-Hg(II)-thymine base pairs for detection of Hg(2.).

Science.gov (United States)

Li, Jiao; Lu, Liping; Kang, Tianfang; Cheng, Shuiyuan

2016-03-15

In this article, we developed an electrochemiluminescence (ECL) sensor with a high-intensity charge transfer interface for Hg(2+) detection based on Hg(II)-induced DNA hybridization. The sensor was fabricated by the following simple method. First, graphene oxide (GO) was electrochemically reduced onto a glassy carbon electrode through cyclic voltammetry. Then, amino-labeled double-stranded (ds)DNA was assembled on the electrode surface using 1-pyrenebutyric acid N-hydroxysuccinimide as a linker between GO and DNA. The other terminal of dsDNA, which was labeled with biotin, was linked to CdSe quantum dots via biotin-avidin interactions. Reduced graphene oxide has excellent electrical conductivity. dsDNA with T-Hg(II)-T base pairs exhibited more facile charge transfer. They both accelerate the electron transfer performance and sensitivity of the sensor. The increased ECL signals were logarithmically linear with the concentration of Hg(II) when Hg(2+) was present in the detection solution. The linear range of the sensor was 10(-11) to 10(-8)mol/L (R=0.9819) with a detection limit of 10(-11)mol/L. This biosensor exhibited satisfactory results when it was used to detect Hg(II) in real water samples. The biosensor with high-intense charge transfer performance is a prospect avenue to pursue more and more sensitive detection method. Copyright © 2015 Elsevier B.V. All rights reserved.

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa.

Science.gov (United States)

Liu, Bing; Wang, Chaogang; Liu, Danxia; He, Ning; Deng, Xu

2017-01-01

A pigmented yeast R1 with strong tolerance to Hg2+ was isolated. Phylogenetic identification based on the analysis of 26S rDNA and ITS revealed R1 is a Rhodotorula mucilaginosa species. R1 was able to grow in the presence of 80 mg/L Hg2+, but the lag phase was much prolonged compared to its growth in the absence of Hg2+. The maximum Hg2+ binding capacity of R1 was 69.9 mg/g, and dead cells could bind 15% more Hg2+ than living cells. Presence of organic substances drastically reduced bioavailability of Hg2+ and subsequently decreased Hg2+ removal ratio from aqueous solution, but this adverse effect could be remarkably alleviated by the simultaneous process of cell propagation and Hg2+ biouptake with actively growing R1. Furthermore, among the functional groups involved in Hg2+ binding, carboxyl group contributed the most, followed by amino & hydroxyl group and phosphate group. XPS analysis disclosed the mercury species bound on yeast cells was HgCl2 rather than HgO or Hg0.

Quantitative imaging of D-2-hydroxyglutarate (D2HG in selected histological tissue areas by a novel bioluminescence technique

Directory of Open Access Journals (Sweden)

Nadine Fabienne Voelxen

2016-03-01

Full Text Available AbstractPatients with malignant gliomas have a poor prognosis with average survival of less than one year. Whereas in other tumor entities the characteristics of tumor metabolism are successfully used for therapeutic approaches, such developments are very rare in brain tumors, notably in gliomas. One metabolic feature characteristic of gliomas, in particular diffuse astrocytomas and oligodendroglial tumors, is the variable content of D-2-hydroxyglutarate (D2HG, a metabolite, which was discovered first in this tumor entity. D2HG is generated in large amounts due to various gain-of–function mutations in the isocitrate dehydrogenases IDH-1 and IDH-2. Meanwhile, D2HG has been detected in several other tumor entities including intrahepatic bile-duct cancer, chondrosarcoma, acute myeloid leukemia, and angioimmunoblastic T-cell lymphoma. D2HG is barely detectable in healthy tissue (< 0.1 mM, but its concentration increases up to 35 mM in malignant tumor tissues. Consequently, the oncometabolite D2HG has gained increasing interest in the field of tumor metabolism. To facilitate its quantitative measurement without loss of spatial resolution at a microscopical level, we have developed a novel bioluminescence assay for determining D2HG in sections of snap-frozen tissue. The assay was verified independently by photometric tests and liquid chromatography / mass spectrometry (LC/MS. The novel technique allows the microscopically resolved determination of D2HG in a concentration range of 0 – 10 µmol/g tissue (wet weight. In combination with the already established bioluminescence imaging techniques for ATP, glucose, pyruvate, and lactate, the novel D2HG assay enables a comparative characterization of the metabolic profile of individual tumors in a further dimension.

Determination of MeHg sources to fish in the St. Louis River, MN, USA, using Hg stable isotopes

Science.gov (United States)

Mercury contamination in the Great Lakes region has become a prevalent concern due to elevated methylmercury (MeHg) levels in fish. While atmospheric deposition of Hg is ubiquitous, releases from legacy point-sources give rise to numerous Areas of Concern (AOCs) across the Great ...

The simplest representative of a complex series. The Hg-rich amalgam Yb{sub 11}Hg{sub 54}

Energy Technology Data Exchange (ETDEWEB)

Tambornino, Frank; Hoch, Constantin [LMU Muenchen (Germany). Dept. Chemie

2017-09-01

Yb{sub 11}Hg{sub 54} is a new member of a series of amalgams with composition close to MHg{sub 5}. Its crystal structure was solved and refined on the basis of single crystal data. The structure model was confirmed with a Rietveld refinement. Yb{sub 11}Hg{sub 54} has the first crystal structure in this family in which no disorder effects such as mixed occupation, split positions or superstructure formation is observed. It therefore can be regarded as a parent structure for all other amalgams. The crystal structure of Yb{sub 11}Hg{sub 54} can be derived from the Gd{sub 14}Ag{sub 51} structure type, the aristotype of this family. We give a detailed crystal structure description for Yb{sub 11}Hg{sub 54} and discuss it in the context of the further known crystal structures closely related. A ranking within this structure family can be established by calculating features for the structural complexity for all structures, including the individual disorder phenomena.

Highly Efficient Spin-to-Charge Current Conversion in Strained HgTe Surface States Protected by a HgCdTe Layer

Science.gov (United States)

Noel, P.; Thomas, C.; Fu, Y.; Vila, L.; Haas, B.; Jouneau, P.-H.; Gambarelli, S.; Meunier, T.; Ballet, P.; Attané, J. P.

2018-04-01

We report the observation of spin-to-charge current conversion in strained mercury telluride at room temperature, using spin pumping experiments. We show that a HgCdTe barrier can be used to protect the HgTe from direct contact with the ferromagnet, leading to very high conversion rates, with inverse Edelstein lengths up to 2.0 ±0.5 nm . The influence of the HgTe layer thickness on the conversion efficiency is found to differ strongly from what is expected in spin Hall effect systems. These measurements, associated with the temperature dependence of the resistivity, suggest that these high conversion rates are due to the spin momentum locking property of HgTe surface states.

Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in $^{184,186}$Hg and two-state mixing calculations

CERN Document Server

Gaffney, L P; Page, R.D.; Grahn, T.; Scheck, M.; Butler, P.A.; Bertone, P.F.; Bree, N.; Carroll, R.J.; Carpenter, M.P.; Chiara, C.J.; Dewald, A.; Filmer, F.; Fransen, C.; Huyse, M.; Janssens, R.V.F.; Joss, D.T.; Julin, R.; Kondev, F.G.; Nieminen, P.; Pakarinen, J.; Rigby, S.V.; Rother, W.; Van Duppen, P.; Watkins, H.V.; Wrzosek-Lipska, K.; Zhu, S.

2014-01-01

The neutron-deficient mercury isotopes, $^{184,186}$Hg, were studied with the Recoil Distance Doppler Shift (RDDS) method using the Gammasphere array and the K\\"oln Plunger device. The Differential Decay Curve Method (DDCM) was employed to determine the lifetimes of the yrast states in $^{184,186}$Hg. An improvement on previously measured values of yrast states up to $8^{+}$ is presented as well as first values for the $9_{3}$ state in $^{184}$Hg and $10^{+}$ state in $^{186}$Hg. $B(E2)$ values are calculated and compared to a two-state mixing model which utilizes the variable moment of inertia (VMI) model, allowing for extraction of spin-dependent mixing strengths and amplitudes.

40 CFR 60.4152 - Responsibilities of Hg authorized account representative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Responsibilities of Hg authorized... and Compliance Times for Coal-Fired Electric Steam Generating Units Hg Allowance Tracking System § 60.4152 Responsibilities of Hg authorized account representative. Following the establishment of a Hg...

Terahertz emission from CdHgTe/HgTe quantum wells with an inverted band structure

Energy Technology Data Exchange (ETDEWEB)

Vasilyev, Yu. B., E-mail: Yu.Vasilyev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Mikhailov, N. N. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Vasilyeva, G. Yu.; Ivánov, Yu. L.; Zakhar’in, A. O.; Andrianov, A. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Vorobiev, L. E.; Firsov, D. A. [Peter the Great Saint-Petersburg Polytechnic University (Russian Federation); Grigoriev, M. N. [Ustinov Baltic State Technical University “VOENMEKh” (Russian Federation); Antonov, A. V.; Ikonnikov, A. V.; Gavrilenko, V. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-07-15

The terahertz electroluminescence from Cd{sub 0.7}Hg{sub 0.3}Te/HgTe quantum wells with an inverted band structure in lateral electric fields is experimentally detected and studied. The emission-spectrum maximum for wells 6.5 and 7 nm wide is near 6 meV which corresponds to interband optical transitions. The emission is explained by state depletion in the valence band and conduction band filling due to Zener tunneling, which is confirmed by power-law current–voltage characteristics.

High-resolution Hg Chemostratigraphy

DEFF Research Database (Denmark)

Sial, Alcides N.; Chen, J.; Lacerda, L.D.

2014-01-01

of Gubbio (Italy) and Stevns Klint (Denmark) where the KTB layer is easily recognizable, and at a near-complete succession exposed at the Bajada del Jagüel locality in the Neuquén Basin, Argentina. These three localities display similar δ13Ccarb trends with markedly negative excursion at the KTB layer. Bulk-rock...... one at Stevns Klint points to a cycle of warm followed by colder climate. At Stevns Klint, Hg contents reach 250 ng g− 1 within the KTB layer (Fiskeler Member) and 45 ng.g− 1 at 1.5 m above that, while within the Scaglia Rossa Formation at Gubbio, three Hg peaks across the KTB are observed, one...

Mercury contamination in human hair and fish from Cambodia: levels, specific accumulation and risk assessment

International Nuclear Information System (INIS)

Agusa, Tetsuro; Kunito, Takashi; Iwata, Hisato; Monirith, In; Tana, Touch Seang; Subramanian, Annamalai; Tanabe, Shinsuke

2005-01-01

Mercury (Hg) concentrations in human hair and fish samples from Phnom Penh, Kien Svay, Tomnup Rolork and Batrong, Cambodia, collected in November 1999 and December 2000 were determined to understand the status of contamination, and age- and sex-dependent accumulation in humans and to assess the intake of mercury via fish consumption. Mercury concentrations in human hair ranged from 0.54 to 190 μg/g dry wt. About 3% of the samples contained Hg levels exceeding the no observed adverse effects level (NOAEL) of WHO (50 μg/g) and the levels in some hair samples of women also exceeded the NOAEL (10 μg/g) associated with fetus neurotoxicity. A weak but significant positive correlation was observed between age and Hg levels in hair of residents. Mercury concentrations in muscle of marine and freshwater fish from Cambodia ranged from <0.01 to 0.96 μg/g wet wt. Mercury intake rates were estimated on the basis of the Hg content in fish and daily fish consumption. Three samples of marine fish including sharp-tooth snapper and obtuse barracuda, and one sample of sharp-tooth snapper exceeded the guidelines by US EPA and by Joint FAO/WHO Expert Committee on Food Additives (JECFA), respectively, which indicates that some fish specimens examined (9% and 3% for US EPA and JECFA guidelines, respectively) were hazardous for consumption at the ingestion rate of Cambodian people (32.6 g/day). It is suggested that fish is probably the main source of Hg for Cambodian people. However, extremely high Hg concentrations were observed in some individuals and could not be explained by Hg intake from fish consumption, indicating some other contamination sources of Hg in Cambodia. - A source other than fish may be responsible for high Hg in some Cambodians

40 CFR 60.4154 - Compliance with Hg budget emissions limitation.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Compliance with Hg budget emissions... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Tracking System § 60.4154 Compliance with Hg budget emissions limitation. (a) Allowance transfer deadline. The Hg allowances are available...

HgCdTe e-avalanche photodiode detector arrays

Directory of Open Access Journals (Sweden)

Anand Singh

2015-08-01

Full Text Available Initial results on the MWIR e-APD detector arrays with 30 μm pitch fabricated on LPE grown compositionally graded p-HgCdTe epilayers are presented. High dynamic resistance times active area (R0A product 2 × 106 Ω-cm2, low dark current density 4 nA/cm2 and high gain 5500 at -8 V were achieved in the n+-υ-p+ HgCdTe e-APD at 80 K. LPE based HgCdTe e-APD development makes this technology amenable for adoption in the foundries established for the conventional HgCdTe photovoltaic detector arrays without any additional investment.

Seasonal and diurnal variations of Hg° over New England

Directory of Open Access Journals (Sweden)

J. D. Hegarty

2008-03-01

Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by AIRMAP at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and two month measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol in winter, a dry deposition velocity of ~0.20 cm s−1 with a ~16 day lifetime in the coastal boundary layer in summer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous distribution of Hg° over North American in winter due to its long lifetime and/or rapid removal of reactive mercury from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects Hg° loss relative to changes in CO more than their emission ratio.

Relationship of non-protein thiol pools and accumulated Cd or Hg in the marine macrophyte Posidonia oceanica (L.) Delile

International Nuclear Information System (INIS)

Maserti, B.E.; Ferrillo, V.; Avdis, O.; Nesti, U.; Di Garbo, A.; Catsiki, A.; Maestrini, P.L.

2005-01-01

The accumulation of cadmium or mercury and the effect of these elements on the levels of non-protein thiols in the blades of the marine macrophyte Posidonia oceanica were investigated. A significant accumulation of cadmium or mercury, dependent on metal concentration supplied, was observed in metal-treated blades. In the blades treated either with cadmium or mercury, a significant increase in the levels of non-protein thiols (other than glutathione) and a marked depletion of the reduced glutathione content as a function of the metal, exposure time and metal concentration supplied were found. This investigation provides first experimental report on the relationship between non-protein thiol pools and accumulated cadmium or mercury in P. oceanica

Sunlight Modulates Fruit Metabolic Profile and Shapes the Spatial Pattern of Compound Accumulation within the Grape Cluster.

Science.gov (United States)

Reshef, Noam; Walbaum, Natasha; Agam, Nurit; Fait, Aaron

2017-01-01

Vineyards are characterized by their large spatial variability of solar irradiance (SI) and temperature, known to effectively modulate grape metabolism. To explore the role of sunlight in shaping fruit composition and cluster uniformity, we studied the spatial pattern of incoming irradiance, fruit temperature and metabolic profile within individual grape clusters under three levels of sunlight exposure. The experiment was conducted in a vineyard of Cabernet Sauvignon cv. located in the Negev Highlands, Israel, where excess SI and midday temperatures are known to degrade grape quality. Filtering SI lowered the surface temperature of exposed fruits and increased the uniformity of irradiance and temperature in the cluster zone. SI affected the overall levels and patterns of accumulation of sugars, organic acids, amino acids and phenylpropanoids, across the grape cluster. Increased exposure to sunlight was associated with lower accumulation levels of malate, aspartate, and maleate but with higher levels of valine, leucine, and serine, in addition to the stress-related proline and GABA. Flavan-3-ols metabolites showed a negative response to SI, whereas flavonols were highly induced. The overall levels of anthocyanins decreased with increased sunlight exposure; however, a hierarchical cluster analysis revealed that the members of this family were grouped into three distinct accumulation patterns, with malvidin anthocyanins and cyanidin-glucoside showing contrasting trends. The flavonol-glucosides, quercetin and kaempferol, exhibited a logarithmic response to SI, leading to improved cluster uniformity under high-light conditions. Comparing the within-cluster variability of metabolite accumulation highlighted the stability of sugars, flavan-3-ols, and cinnamic acid metabolites to SI, in contrast to the plasticity of flavonols. A correlation-based network analysis revealed that extended exposure to SI modified metabolic coordination, increasing the number of negative

Absolute cross sections for emission of 284.7-nm (Hg II) and 479.7-nm (Hg III) radiation in electron--mercury-ion collisions

International Nuclear Information System (INIS)

Phaneuf, R.A.; Taylor, P.O.; Dunn, G.H.

1976-01-01

Crossed beams of electrons and Hg + ions have been used to measure absolute cross sections for emission of 284.7-nm radiation, resulting from excitation of a predominantly ground-state Hg + target to the 7s 2 S 1 / 2 state. Values range from 3 x 10 -17 cm 2 near threshold, where the cross section is strongly peaked, to 1.3 x 10 -18 cm 2 at 280 eV. Also reported are some measurements of emission of 479.7-nm (Hg III) radiation, resulting from electron impact on both Hg + and Hg ++ targets. Cross sections range from approximately 5 x 10 -19 to 5 x 10 -20 cm 2 , and in the case of electron-Hg ++ collisions, are more than an order of magnitude smaller than predicted by an available semiclassical binary-encounter calculation

Beryllium abundances in Hg-Mn stars

International Nuclear Information System (INIS)

Boesgaard, A.M.; Heacox, W.D.; Wolff, S.C.; Borsenberger, J.; Praderie, F.

1982-01-01

The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm -1 in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10 4 relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies

Transfer in the light Hg isotopes and the U(6/12) models

International Nuclear Information System (INIS)

Vergnes, M.; Grafeuille, S.; Rotbard, G.

1985-01-01

It was suggested recently that the level schemes of the odd Hg isotopes with 193 200 Hg, 198 Hg, 196 Hg(p,d) 199 Hg, 197 Hg, 195 Hg. The comparison of the experimental spectroscopic factors with the ones computed using the U(6/12) model shows that, among the three nuclei studied, 195 Hg and 197 Hg can be considered as reasonably described. The agreement in this case with U(6/12) is better in the U(5) limit than in the O(6) limit

Hubungan Paparan Merkuri (Hg Dengan Kejadian Gangguan Fungsi HatiPada Pekerja Tambang Emas di Wonogiri

Directory of Open Access Journals (Sweden)

Nikie Astorina Yunita Dewanti

2013-12-01

Full Text Available Background: Traditional gold mining activities that using WOA/ amalgamation can cause Hg emissions to the environment. The emissions could raise mercury poisoning in the environment and human. Liver as a major part of the metabolism and accumulation of Hg in the human body, so that Hg could lead to liver damage. In the previous research, Hg exposure in male rats caused hepatotoxicosis. Average blood mercury levels of workers was 53.5 μg/m3. Objective: To determine the association between mercury (Hg exposure and theoccurance of liver dysfunction on gold mine workers at Jendi Village, sub-district Selogiri, Wonogiri District. Methods: It was a cross-sectional study, total sample were 41 workers. The data obtained from the results of laboratory tests of blood samples and the results of the interview respondents.Data would be analyzed using biavariate and multivariate statstic test. Results:There was 41.16% of respondents were miners, processors as well as grates, the average of working period was 10 years, work duration 6 hours a  day and 6 days a week. 97.56% of respondents have blood mercury levels above normal (U.S. EPA: 5.8 ppb. Elevated levels of SGOT experienced by 24.4% of respondents , SGPT 17.1% of  respondents and ALP 58.8% of  respondents or as much as 68.3% of respondents having liver disfunction. There was no difference incidence of liver dysfunction seen from the type of work (p value = 0.459, There was no assossiation between  work duration, work period and blood mercury  levels with the incidence of liver disfunction in workers (p value = 0.148; 0.408 and 0.608. There was a relationship between blood mercury levels with SGPT as an indicator of liver dysfunction (p value = 0.042 Conclusion: Overall, the data did not provide strong evidence that mercury exposure associated with incidence of liver disfunction.   Keywords: mercury exposure, liver disfunction, SGOT, SGPT, ALP

40 CFR 60.4121 - Submission of Hg budget permit applications.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Submission of Hg budget permit... Times for Coal-Fired Electric Steam Generating Units Permits § 60.4121 Submission of Hg budget permit applications. (a) Duty to apply. The Hg designated representative of any Hg Budget source required to have a...

Quadrupole interaction studies of Hg in Sb

International Nuclear Information System (INIS)

Soares, J.C.; Krien, K.; Herzog, P.; Folle, H.R.; Freitag, K.; Reuschenbach, F.; Reuschenbach, M.; Trzcinski, R.

1978-01-01

Time differential perturbed angular correlation and nuclear orientation studies of the electric quadrupole interaction for Hg in Sb have been performed. The effective field gradients at room temperature and below 0.05K have been derived. These two values are no indication for an anomalous temperature dependence of the effective field gradient for Hg in Sb. The value of the electric field gradient fits well into the systematics for Hg in other hosts. It is shown that the electronic enhancements of the field gradients are correlated to the valence of the impurities and are rather insensitive to the host properties. (orig./HPOE) [de

HgCdTe photovoltaic detectors on Si substrates

International Nuclear Information System (INIS)

Zanio, K.R.; Bean, R.C.

1988-01-01

HgCdTe photovoltaic detectors have been fabricated on Si substrates through intermediate CdTe/GaAs layers. Encapsulation of the GaAs between the CdTe and Si prevents unintentional doping of the HgCdTe by Ga and As. Uniform epitaxial GaAs is grown on three inch diameter Si substrates. Detectors on such large area Si substrates will offer hybrid focal plane arrays whose dimensions are not limited by the difference between the coefficients of thermal expansion of the Si signal processor and the substrate for the HgCdTe detector array. The growth of HgCdTe detectors on the Si signal processors for monolithic focal plane arrays is also considered. 40 references

Fluorescence emissions from mixtures of Hg with the noble gases

International Nuclear Information System (INIS)

Woodworth, J.R.

1977-01-01

Fluorescence emissions from mixtures of Hg with high pressure Xe, Kr, and Ar (approx.1 torr Hg, 10 3 --10 4 torr noble gas) have been studied using a short-pulse relativistic electron beam as an excitation source. Hg--noble gas molecular bands were observed on the red sides of the Hg lines (1849 and 2537 A) as well as on the red sides of the Hg visible lines (7 3 S 1 →6 3 P 0 , 1 , 2 ). Temporal histories and production efficiencies of the molecular emissions were determined and a model was formulated for the time histories of the HgXe 2600 A bands. Possible applications to high power laser systems are discussed

Mercury species accumulation and trophic transfer in biological systems using the Almadén mining district (Ciudad Real, Spain) as a case of study.

Science.gov (United States)

Patiño Ropero, M J; Rodríguez Fariñas, N; Mateo, R; Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C

2016-04-01

The impact of mercury (Hg) pollution in the terrestrial environments and the terrestrial food chains including the impact on human food consumption is still greatly under-investigated. In particular, studies including Hg speciation and detoxification strategies in terrestrial animals are almost non-existing, but these are key information with important implications for human beings. Therefore, in this work, we report on Hg species (inorganic mercury, iHg, and monomethylmercury, MeHg) distribution among terrestrial animal tissues obtained from a real-world Hg exposure scenario (Almadén mining district, Spain). Thus, we studied Hg species (iHg and MeHg) and total selenium (Se) content in liver and kidney of red deer (Cervus elaphus; n = 41) and wild boar (Sus scrofa; n = 16). Similar mercury species distribution was found for both red deer and wild boar. Major differences were found between tissues; thus, in kidney, iHg was clearly the predominant species (more than 81%), while in liver, the species distribution was less homogeneous with a percentage of MeHg up to 46% in some cases. Therefore, Hg accumulation and MeHg transfer were evident in terrestrial ecosystems. The interaction between total Se and Hg species has been evaluated by tissue and by animal species. Similar relationships were found in kidney for both Hg species in red deer and wild boar. However, in liver, there were differences between animals. The possible underlying mechanisms are discussed.

Accumulation and elimination of methylmercury in Atlantic cod (Gadus morhua L.) following dietary exposure

Energy Technology Data Exchange (ETDEWEB)

Amlund, Heidi [National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029 Nordnes, 5817 Bergen (Norway)]. E-mail: heidi.amlund@nifes.no; Lundebye, Anne-Katrine [National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029 Nordnes, 5817 Bergen (Norway); Berntssen, Marc H.G. [National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029 Nordnes, 5817 Bergen (Norway)

2007-08-01

Methylmercury is known to bioaccumulate and biomagnify up the marine food chain. Fish from high levels of the marine food chain may contain relatively high concentrations of mercury, and most (>70%) of the mercury found in muscle is methylmercury. In aquaculture, marine protein (mainly fishmeal) is the dominant source of methylmercury, and this raises some concern with regards to fish welfare and consumer safety. A dietary exposure study, including a depuration period, was carried out in order to study the accumulation and elimination of methylmercury in Atlantic cod (Gadus morhua L.), and to estimate the transfer of methylmercury from feed to fish. Fish were sampled throughout a three month exposure period and a three month depuration period. Muscle samples were fractionated into a protein and a lipid fraction by lipid extraction using methanol and chloroform. Mercury and methylmercury were determined by inductively coupled plasma mass spectrometry (ICPMS) and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS), respectively. A continuous accumulation of methylmercury, after a lag period of 10 days, was observed in muscle tissue during the three months exposure to methylmercury (0.95+/-0.03{mu}g Hg/g feed, n=6). After three months, the final concentration in muscle was 0.38+/-0.04{mu}g Hg/gww (n=6), where methylmercury constituted 90-95% of the mercury present. The elimination of methylmercury from muscle was slow and incomplete (within the three months of depuration) with an estimated elimination half-life (t{sub 1/2}) of 377 days. The transfer of methylmercury from feed to Atlantic cod, described by the estimated absorption efficiency, was 38%. In muscle more than 99% of the mercury was found in the protein fraction. These results suggest that Atlantic cod readily takes up dietary methylmercury, which is efficiently accumulated into muscle, where it is incorporated into larger peptides or proteins. Comparable results were found for

Accumulation and elimination of methylmercury in Atlantic cod (Gadus morhua L.) following dietary exposure

International Nuclear Information System (INIS)

Amlund, Heidi; Lundebye, Anne-Katrine; Berntssen, Marc H.G.

2007-01-01

Methylmercury is known to bioaccumulate and biomagnify up the marine food chain. Fish from high levels of the marine food chain may contain relatively high concentrations of mercury, and most (>70%) of the mercury found in muscle is methylmercury. In aquaculture, marine protein (mainly fishmeal) is the dominant source of methylmercury, and this raises some concern with regards to fish welfare and consumer safety. A dietary exposure study, including a depuration period, was carried out in order to study the accumulation and elimination of methylmercury in Atlantic cod (Gadus morhua L.), and to estimate the transfer of methylmercury from feed to fish. Fish were sampled throughout a three month exposure period and a three month depuration period. Muscle samples were fractionated into a protein and a lipid fraction by lipid extraction using methanol and chloroform. Mercury and methylmercury were determined by inductively coupled plasma mass spectrometry (ICPMS) and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS), respectively. A continuous accumulation of methylmercury, after a lag period of 10 days, was observed in muscle tissue during the three months exposure to methylmercury (0.95+/-0.03μg Hg/g feed, n=6). After three months, the final concentration in muscle was 0.38+/-0.04μg Hg/gww (n=6), where methylmercury constituted 90-95% of the mercury present. The elimination of methylmercury from muscle was slow and incomplete (within the three months of depuration) with an estimated elimination half-life (t 1/2 ) of 377 days. The transfer of methylmercury from feed to Atlantic cod, described by the estimated absorption efficiency, was 38%. In muscle more than 99% of the mercury was found in the protein fraction. These results suggest that Atlantic cod readily takes up dietary methylmercury, which is efficiently accumulated into muscle, where it is incorporated into larger peptides or proteins. Comparable results were found for Atlantic salmon

Slow Auger Relaxation in HgTe Colloidal Quantum Dots.

Science.gov (United States)

Melnychuk, Christopher; Guyot-Sionnest, Philippe

2018-05-03

The biexciton lifetimes in HgTe colloidal quantum dots are measured as a function of particle size. Samples produced by two synthetic methods, leading to partially aggregated or well-dispersed particles, exhibit markedly different dynamics. The relaxation characteristics of partially aggregated HgTe inhibit reliable determinations of the Auger lifetime. In well-dispersed HgTe quantum dots, the biexciton lifetime increases approximately linearly with particle volume, confirming trends observed in other systems. The extracted Auger coefficient is three orders of magnitude smaller than that for bulk HgCdTe materials with similar energy gaps. We discuss these findings in the context of understanding Auger relaxation in quantum-confined systems and their relevance to mid-infrared optoelectronic devices based on HgTe colloidal quantum dots.

Photoluminescence from CdxHg1-xTe

International Nuclear Information System (INIS)

Breivik, M; Selvig, E; Tonheim, C R; Brendhagen, E; Brudevoll, T; Rheenen, A D van; Steen, H; Nicolas, S; Lorentzen, T; Haakenaasen, R

2008-01-01

We present important aspects of photoluminescence (PL) of Cd x Hg 1-x Te in the infrared part of the spectrum where background thermal radiation significantly affects the PL spectrum. We show how the background spectrum can be removed from the data. We also show how the wavelength of the excitation laser affects the relative intensity of the PL peaks from a multi-layer structure. Finally, we present temperature dependent PL of a Cd 0.36 Hg 0.64 Te/Cd 0.61 Hg 0.39 Te multiple quantum well structure grown on a 4 μm thick Cd 0.36 Hg 0.64 Te buffer layer. We attribute the low temperature peak from the buffer layer to impurities. The impurity levels are depopulated as the temperature increases, resulting in a decreased PL peak intensity. Above ∼200 K a band-to-band peak from the buffer layer is observed. The quantum well peak persists up to ∼200 K

Electronic properties of liquid Hg-In alloys : Ab-initio molecular dynamics study

International Nuclear Information System (INIS)

Sharma, Nalini; Ahluwalia, P. K.; Thakur, Anil

2016-01-01

Ab-initio molecular dynamics simulations are performed to study the structural properties of liquid Hg-In alloys. The interatomic interactions are described by ab-initio pseudopotentials given by Troullier and Martins. Three liquid Hg-In alloys (Hg_1_0In_9_0, Hg_3_0In_7_0_,_. Hg_5_0In_5_0, Hg_7_0In_3_0, and Hg_9_0Pb_1_0) at 299 K are considered. The calculated results for liquid Hg (l-Hg) and lead (l-In) are also drawn. Along with the calculated results of considered five liquid alloys of Hg-In alloy. The results obtained from electronic properties namely total density of state and partial density of states help to find the local arrangement of Hg and In atoms and the presence of liquid state in the considered five alloys.

Accumulation of Pb, Hg, Cd, Se, Sc, Cr, Rb, Fe, Zn, Co in the plants and sludges of the Lake Balaton

International Nuclear Information System (INIS)

Teherani, D.K.; Altmann, H.; Wallisch, G.

1981-01-01

Various plants (Ceratophyllum demersum, Potamogeton pectinatus, Myriophyllum spicatum) and mud samples taken from Lake Balaton (Paloznak, Balatonfuezfoe) in June 1978 were analyzed for Se, Cr, Sc, Rb, Fe, Zn, Co by neutron activation analysis and for Cd, Pb, Hg by atomic absorption spectrometry. The concentration values found for Se ranged between 0.25-1.2 ppm (plant) and 0.99-1.47 ppm (mud), for Cr 1.6-6 ppm (plant) and 4.85-40.75 ppm (mud), for Sc 0.4-0.75 ppm (plant) and 3.25-5.87 ppm (mud), for Rb 6.75-16 ppm (plant) and 17-48.75 ppm (mud), for Fe 636.7-4491 ppm (plant) and 11034-12057 ppm (mud), for Zn 20.5-38.5 ppm (plant) and 29.75-41.75 ppm (mud), for Co 0.77-4.75 ppm (plant) and 4.87-5.5 ppm (mud), for Pb 4.5-23.5 ppm (plant) and 18-28 ppm (mud), for Cd <0.03 ppm (plant, mud), for Hg <0.01-0.07 ppm (plant) and 0.04-0.08 ppm (mud). (author)

Effect of layer composition on band spectrum of CdxHg1-xTe - CdyHg1-yTe-type superlattices

International Nuclear Information System (INIS)

Gerchikov, L.G.; Subashiev, A.V.; Salman Dalla

1993-01-01

Evolution of energy spectrum of Cd x Hg 1-x Te -Cd y Hg 1-y Te superlattices at variation of layer composition is considered. Transition from 3 type superlattice to 1 type superlattice occurring for y=0.16 is studied comprehensively. In this case, dependence of the width of superlattice forbidden zone on layer thickness is shown to become more smooth, than in CdTe - HgTe superlattice and it gives more possibilities to use such superlattices for making IR phototransistors. 10 refs., 4 figs

Label-free colorimetric detection of Hg²⁺ based on Hg²⁺-triggered exonuclease III-assisted target recycling and DNAzyme amplification.

Science.gov (United States)

Ren, Wang; Zhang, Ying; Huang, Wei Tao; Li, Nian Bing; Luo, Hong Qun

2015-06-15

This work reported a label-free colorimetric assay for sensitive detection of Hg(2+) based on Hg(2+)-triggered hairpin DNA probe (H-DNA) termini-binding and exonuclease Ш (Exo Ш)-assisted target recycling, as well as hemin/G-quadruplex (DNAzyme) signal amplification. The specific binding of free Hg(2+) with the thymine-thymine (T-T) mismatches termini of H-DNA could immediately trigger the Exo Ш digestion, and then set free G-quadruplex segments and Hg(2+). The Exo Ш impellent recycling of ultratrace Hg(2+) produced numerous G-quadruplexes. The corresponding DNAzymes catalyzed efficiently the H2O2-mediated oxidation of the ABTS(2-) to the colored product in the presence of hemin. Using the color change as the output signal, and the Exo Ш-aided Hg(2+) recycling and DNAzyme as the signal amplifier, the ultrasensitive assay system successfully achieved visual detection of Hg(2+) as low as 1.0 nM by the naked eye, and was suitable for field monitoring. The calibration curve was linear in the range of 50.0 pM to 20.0 nM for Hg(2+) (R=0.9962) with a detection limit of 10.0 pM. Moreover, this proposed strategy showed excellent selectivity, portability and low-cost, and was successfully applied to colorimetric detection of Hg(2+) in laboratory tap water and Jialing river water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Which Factors Determine Metal Accumulation in Agricultural Soils in the Severely Human-Coupled Ecosystem?

Science.gov (United States)

Xu, Li; Cao, Shanshan; Wang, Jihua; Lu, Anxiang

2016-05-17

Agricultural soil is typically an important component of urban ecosystems, contributing directly or indirectly to the general quality of human life. To understand which factors influence metal accumulation in agricultural soils in urban ecosystems is becoming increasingly important. Land use, soil type and urbanization indicators all account for considerable differences in metal accumulation in agricultural soils, and the interactions between these factors on metal concentrations were also examined. Results showed that Zn, Cu, and Cd concentrations varied significantly among different land use types. Concentrations of all metals, except for Cd, were higher in calcareous cinnamon soil than in fluvo-aquic soil. Expansion distance and road density were adopted as urbanization indicators, and distance from the urban center was significantly negatively correlated with concentrations of Hg, and negatively correlated with concentrations of Zn, and road density was positively correlated with Cd concentrations. Multivariate analysis of variance indicated that Hg concentration was significantly influenced by the four-way interaction among all factors. The results in this study provide basic data to support the management of agricultural soils and to help policy makers to plan ahead in Beijing.

40 CFR 60.4110 - Authorization and Responsibilities of Hg designated representative.

Science.gov (United States)

2010-07-01

... Hg designated representative. 60.4110 Section 60.4110 Protection of Environment ENVIRONMENTAL... Emission Guidelines and Compliance Times for Coal-Fired Electric Steam Generating Units Hg Designated Representative for Hg Budget Sources § 60.4110 Authorization and Responsibilities of Hg designated representative...

Active transport, substrate specificity, and methylation of Hg(II) in anaerobic bacteria

Science.gov (United States)

Schaefer, Jeffra K.; Rocks, Sara S.; Zheng, Wang; Liang, Liyuan; Gu, Baohua; Morel, François M. M.

2011-01-01

The formation of methylmercury (MeHg), which is biomagnified in aquatic food chains and poses a risk to human health, is effected by some iron- and sulfate-reducing bacteria (FeRB and SRB) in anaerobic environments. However, very little is known regarding the mechanism of uptake of inorganic Hg by these organisms, in part because of the inherent difficulty in measuring the intracellular Hg concentration. By using the FeRB Geobacter sulfurreducens and the SRB Desulfovibrio desulfuricans ND132 as model organisms, we demonstrate that Hg(II) uptake occurs by active transport. We also establish that Hg(II) uptake by G. sulfurreducens is highly dependent on the characteristics of the thiols that bind Hg(II) in the external medium, with some thiols promoting uptake and methylation and others inhibiting both. The Hg(II) uptake system of D. desulfuricans has a higher affinity than that of G. sulfurreducens and promotes Hg methylation in the presence of stronger complexing thiols. We observed a tight coupling between Hg methylation and MeHg export from the cell, suggesting that these two processes may serve to avoid the build up and toxicity of cellular Hg. Our results bring up the question of whether cellular Hg uptake is specific for Hg(II) or accidental, occurring via some essential metal importer. Our data also point at Hg(II) complexation by thiols as an important factor controlling Hg methylation in anaerobic environments. PMID:21555571

Density of liquid Hg(1-x)Cd(x)Te

Science.gov (United States)

Chandra, D.; Holland, L. R.

1983-01-01

Negative thermal expansion has been established in liquid Hg(1-x)Cd(x)Te for x less than 0.2 employing a pycnometric method. Pure HgTe increases in density from its melting point at 670 C to a maximum value at 750 C, where normal thermal expansion progressively resumes. The dependence of density on temperature for liquid Hg(1-x)Cd(x)Te arises almost exclusively from the HgTe portion of the melt, while CdTe acts as a diluent. The temperature corresponding to the maximum density changes slightly with composition, increasing by about 5 C for x = 0.1.

Phase diagrams of ZnTe-HgTe-Te and ZnTe-CdTe-HgTe-Te systems

International Nuclear Information System (INIS)

Andrukhiv, A.M.; Litvak, A.M.; Mironov, K.E.

1992-01-01

ZnTe-HgTe-Te system liquidus surface is investigated and solid solution layers are produced in this system by the method of liquid-phase epitaxy (LPE). The theoretical analysis of experimental and theoretical data allows to calculate the diagram of ZnTe-CdTe-HgTe-Te system fusibility. A significant effect of elastic stresses of the epitaxial layer, grown on CdTe substrate, on the process of LPE of solid solutions is established

Mechanisms of Hg(II) uptake and methylation in methylating bacteria

Energy Technology Data Exchange (ETDEWEB)

Morel, Francois M. M. [Princeton Univ., NJ (United States). Geosciences

2016-10-14

The goal of this project was to understand the critical factors which control the availability and transport of Hg(II) into cells, a first step in the production of the neurotoxin, methylmercury. Specifically, this research focused on understanding the mechanism of bacterial mercury uptake and how mercury speciation affects the specificity and kinetics of mercury transport. Our research has shown that Hg(II) uptake in three different iron and sulfate-reducing proteobacteria occurs by the following mechanism (1) : Hg(II) uptake is an active transport process requiring energy, (2) it is dependent upon the structure of the Hg binding ligand, and (3) it is mediated by a heavy metal transporter such as one which transports the essential metal, Zn(II). In order to determine whether this mechanism extends to more diverse phylogenetic groups, we have begun examining Hg(II) uptake and bioavailability in two representative Hg methylating strains within the Firmicutes. These organisms have remarkably different membrane structures distinct from the Proteobacteria. Our results show low uptake rates in these two species of Firmicutes relative to the previously characterized Proteobacteria. This may explain the low methylation rates and yields observed in these organisms. Most surprisingly, however, these organisms appear to take up Hg(II) passively, as the addition of a protonophore failed to reduce Hg(II) uptake in these organisms. This is quite different to what has been observed previously for the Proteobacteria and suggests a different mechanism for Hg(II) uptake in the Firmicutes. We are continuing to understand and describe Hg(II) uptake in these organisms. A manuscript is expected to be submitted on this research in June 2016.

Hg(II) removal from aqueous solutions by bacillus subtilis biomass

Energy Technology Data Exchange (ETDEWEB)

Wang, Xue Song; Li, Fei Yan; He, Wen; Miao, Hua Hua [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang (China)

2010-01-15

The biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (<20 mg Hg/L). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Toxicity of mercury (Hg on survival and growth rate, hemato- and histopathological parameters ofOreochromis niloticus

Directory of Open Access Journals (Sweden)

Kukuh Nirmala

2013-11-01

Full Text Available Heavy metals are serious pollutants of the aquatic environment because of their environmental persistence and ability to be accumulated by aquatic organisms. Oreochromis niloticus exposed to 0, 0.16, 0.5, and 1.0 ppm Hg for 30 days. The aim of this study was to determine the influence of mercury in water on survival rate, growth rates, hematological, and histological parameters of Oreochromis niloticus. This study was conducted from Mei to June 2009. The experimental design was arranged in completely randomized design with four treatments and three replications. Stock density was 8 fish/aquarium with mean initial body weight was 15.70±1.13 g. Growth and survival rates of test fish were decreased with increasing the Hg concentration. Red blood cell (RBC count, haematocrit content, and haemoglobin content decreased when compared to the control. The number of white blood cells (WBC increased in mercuric treated fish. The results are statistically significant at p<0.05 level. Keywords:mercury, survival and growth rate, hematology, histopathology, Oreochromis niloticus

Accumulation and distribution of mercury in fruiting bodies by fungus Suillus luteus foraged in Poland, Belarus and Sweden.

Science.gov (United States)

Saba, Martyna; Falandysz, Jerzy; Nnorom, Innocent C

2016-02-01

Presented in this paper is result of the study of the bioconcentration potential of mercury (Hg) by Suillus luteus mushroom collected from regions within Central, Eastern, and Northern regions of Europe. As determined by cold-vapor atomic absorption spectroscopy, the Hg content varied from 0.13 ± 0.05 to 0.33 ± 0.13 mg kg(-1) dry matter for caps and from 0.038 ± 0.014 to 0.095 ± 0.038 mg kg(-1) dry matter in stems. The Hg content of the soil substratum (0-10 cm layer) underneath the fruiting bodies showed generally low Hg concentrations that varied widely ranging from 0.0030 to 0.15 mg kg(-1) dry matter with mean values varying from 0.0078 ± 0.0035 to 0.053 ± 0.025 mg kg(-1) dry matter, which is below typical content in the Earth crust. The caps were observed to be on the richer in Hg than the stems at ratio between 1.8 ± 0.4 and 5.3 ± 2.6. The S. luteus mushroom showed moderate ability to accumulate Hg with bioconcentration factor (BCF) values ranging from 3.6 ± 1.3 to 42 ± 18. The consumption of fresh S. luteus mushroom in quantities up to 300 g week(-1) (assuming no Hg ingestion from other foods) from background areas in the Central, Eastern, and Northern part of Europe will not result in the intake of Hg exceeds the provisional weekly tolerance limit (PTWI) of 0.004 mg kg(-1) body mass.

40 CFR 75.38 - Standard missing data procedures for Hg CEMS.

Science.gov (United States)

2010-07-01

... Hg CEMS. 75.38 Section 75.38 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard missing data procedures for Hg CEMS. (a) Once 720 quality assured monitor operating hours of Hg... substitute data for Hg concentration in accordance with the procedures in ( 75.33(b)(1) through (b)(4...

40 CFR 60.4122 - Information requirements for Hg budget permit applications.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Information requirements for Hg budget... requirements for Hg budget permit applications. A complete Hg Budget permit application shall include the following elements concerning the Hg Budget source for which the application is submitted, in a format...

Nuclear shape staggering in very neutron deficient Hg isotopes detected by laser spectroscopy

International Nuclear Information System (INIS)

Dabkiewicz, P.; Duke, C.; Fischer, H.; Kuehl, T.; Kluge, H.-J.

1978-01-01

The isotope shift in the lambda = 2537 A line of the even isotopes 206 Hg, 190 Hg, 188 Hg, 186 Hg, 184 Hg as well as of the I = 13/2 isomers of 191 Hg, 189 Hg, 187 Hg, 185 Hg has been measured by use of a tunable dye laser at the on-line masseparator ISOLDE at CERN. The resulting delta 2 > values follow the line, extrapolated from the chain 205 Hg- 187 Hg which is known to have spherical nuclear shape at the heavy end changing smoothly to slight oblate deformation for the lighter isotopes. Previous measurements of the I = 1/2 groundstates of 181 Hg. 183 Hg and 185 Hg revealed a sharp shape transition to strong deformation. Combined with the new results the following effects can be proved for the first time from the model-independent quantity delta 2 >: 1) the existence of odd even-shape staggering, 2) the coexistence of very different shapes in one and the same nucleus as manifested by the huge isomer shift in 185 Hg, 3) the absence of mixing of the different shapes. (author)

Environmental contamination of mercury from Hg-mining areas in Wuchuan, northeastern Guizhou, China

International Nuclear Information System (INIS)

Qiu Guangle; Feng Xinbin; Wang Shaofeng; Shang Lihai

2006-01-01

Total Hg and methyl-Hg were evaluated in mine wastes, soils, water, and vegetations from the Wuchuan Hg-mining areas, Guizhou, China. Mine wastes contain high total Hg concentrations, ranging from 79 to 710 μg g -1 , and methyl-Hg from 0.32 to 3.9 ng g -1 . Total Hg in soil samples range from 0.33 to 320 μg g -1 and methyl-Hg from 0.69 to 20 ng g -1 . Vegetations present a high average total Hg concentration of 260 ng g -1 , which greatly exceeds the maximum Hg concentration of 20 ng g -1 recommended by the Chinese National Standard Agency for food sources. The rice samples contain elevated methyl-Hg concentrations, ranging from 4.2 to 18 ng g -1 . Stream water collected from Hg-mining areas is also contaminated, containing Hg as high as 360 ng l -1 , and methyl-Hg reaches up to 5.7 ng l -1 . Data indicate heavy Hg-contaminations and significant conversion of methyl-Hg in the study areas. - Mercury mining activities in Wuchun, Guizhou, China have resulted in seriously mercury contamination to the local environment

Environmental contamination of mercury from Hg-mining areas in Wuchuan, northeastern Guizhou, China

Energy Technology Data Exchange (ETDEWEB)

Qiu Guangle [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 73 Guanshui Road, Guiyang, Guizhou 550002 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Feng Xinbin [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 73 Guanshui Road, Guiyang, Guizhou 550002 (China)]. E-mail: fengxinbin@vip.skleg.cn; Wang Shaofeng [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 73 Guanshui Road, Guiyang, Guizhou 550002 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Shang Lihai [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 73 Guanshui Road, Guiyang, Guizhou 550002 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China)

2006-08-15

Total Hg and methyl-Hg were evaluated in mine wastes, soils, water, and vegetations from the Wuchuan Hg-mining areas, Guizhou, China. Mine wastes contain high total Hg concentrations, ranging from 79 to 710 {mu}g g{sup -1}, and methyl-Hg from 0.32 to 3.9 ng g{sup -1}. Total Hg in soil samples range from 0.33 to 320 {mu}g g{sup -1} and methyl-Hg from 0.69 to 20 ng g{sup -1}. Vegetations present a high average total Hg concentration of 260 ng g{sup -1}, which greatly exceeds the maximum Hg concentration of 20 ng g{sup -1} recommended by the Chinese National Standard Agency for food sources. The rice samples contain elevated methyl-Hg concentrations, ranging from 4.2 to 18 ng g{sup -1}. Stream water collected from Hg-mining areas is also contaminated, containing Hg as high as 360 ng l{sup -1}, and methyl-Hg reaches up to 5.7 ng l{sup -1}. Data indicate heavy Hg-contaminations and significant conversion of methyl-Hg in the study areas. - Mercury mining activities in Wuchun, Guizhou, China have resulted in seriously mercury contamination to the local environment.

Health risk assessment of heavy metals in fish and accumulation patterns in food web in the upper Yangtze River, China.

Science.gov (United States)

Yi, Yujun; Tang, Caihong; Yi, Tieci; Yang, Zhifeng; Zhang, Shanghong

2017-11-01

This study aims to concern the distribution of As, Cr, Cd, Hg, Cu, Zn, Pb and Fe in surface sediment, zoobenthos and fishes, and quantify the accumulative ecological risk and human health risk of metals in river ecological system based on the field investigation in the upper Yangtze River. The results revealed high ecological risk of As, Cd, Cu, Hg, Zn and Pb in sediment. As and Cd in fish presented potential human health risk of metals by assessing integrated target hazard quotient results based on average and maximum concentrations, respectively. No detrimental health effects of heavy metals on humans were found by daily fish consumption. While, the total target hazard quotient (1.659) exceeding 1, it meant that the exposed population might experience noncarcinogenic health risks from the accumulative effect of metals. Ecological network analysis model was established to identify the transfer routes and quantify accumulative effects of metals on river ecosystem. Control analysis between compartments showed large predator fish firstly depended on the omnivorous fish. Accumulative ecological risk of metals indicated that zoobenthos had the largest metal propagation risk and compartments located at higher trophic levels were not easier affected by the external environment pollution. A potential accumulative ecological risk of heavy metal in the food web was quantified, and the noncarcinogenic health risk of fish consumption was revealed for the upper reach of the Yangtze River. Copyright © 2017 Elsevier Inc. All rights reserved.

Crystallographic isomorphism in the structural type of α-HgI{sub 2} by example of KHgI{sub 3} · H{sub 2}O, β-Ag{sub 2}HgI{sub 4}, and β-Cu{sub 2}HgI{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Borisov, S. V., E-mail: borisov@niic.nsc.ru; Magarill, S. A.; Pervukhina, N. V. [Russian Academy of Sciences, Nikolaev Institute of Inorganic Chemistry, Siberian Branch (Russian Federation)

2017-03-15

The structure of KHgI{sub 3} · H{sub 2}O is assigned to the family of crystal structures having the three-layer cubic packing of iodine anions with cations in the tetrahedral voids (the structures of α-HgI{sub 2}, β-Ag{sub 2}HgI{sub 4}, and β-Cu{sub 2}HgI{sub 4} among them). Crystallographic analysis shows that the nodes of the three-layer close packing are populated by iodine anions and K cations in the ratio 3/4: 1/4. Transformation of the structure of α-HgI{sub 2} into the structure of KHgI{sub 3} · H{sub 2}O can be formally represented as the replacement of (HgI){sub n}{sup +} fragments by (KH{sub 2}O){sub n}{sup +} fragments: (Hg{sub 2}I{sub 4})–(HgI){sup +} + (KH{sub 2}O){sub n}{sup +} = KHgI{sub 3} · H{sub 2}O. Perforated layers of vertex-sharing HgI{sub 4} tetrahedra break down into parallel isolated chains. Channels formed in place of I–Hg–I–Hg–fragments are occupied by–H{sub 2}O–K–-H{sub 2}-O-K-H{sub 2}O-chains weakly bound to neighbors.

A New Trapped Ion Clock Based on Hg-201(+)

Science.gov (United States)

Taghavi-Larigani, S.; Burt, E. A.; Lea, S. N.; Prestage, J. D.; Tjoelker, R. L.

2009-01-01

There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave clock: Hg-199(+) and Hg-201(+). Virtually all trapped mercury ion clocks to date have used the 199 isotope. We have begun to investigate the viability of a trapped ion clock based on Hg-201(+). We have measured the unperturbed frequency of the (S-2)(sub 1/2) F = 1, m(sub F) = 0 to (S-2)(sub 1/2) F = 2, m(sub F) = 0 clock transition to be 29.9543658211(2) GHz. In this paper we describe initial measurements with Hg-201(+) and new applications to clocks and fundamental physics.

Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum.

Science.gov (United States)

Samsur, Mohamad; Takatani, Tomohiro; Yamaguchi, Yasunaga; Sagara, Takefumi; Noguchi, Tamao; Arakawa, Osamu

2007-02-01

The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment.

Iminocoumarin-based Hg(II) Ion Probe

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Jung; Park, Sun Young; Lee, Su Yeon; Kim, Ja Hyung; Kim, Jong Seung [Korea Univ., Seoul (Korea, Republic of); Kim, Young Mee; Kim, Sung Jin [Ewha Womans Univ., Seoul (Korea, Republic of); No, Kwang Hyun [Sookmyung Womens Univ., Seoul (Korea, Republic of)

2010-01-15

The design and synthesis of new chemosensors for heavy and transition metal ions (HTM) has been an important subject in the field of supramolecular chemistry due to their fundamental role in biological, environmental, and chemical processes. Particularly, the recognition and detection of Hg{sup 2+} are of growing interest because the Hg{sup 2+} is considered highly noxious elements. Many analytical methods have been applied for this purpose including atomic absorption spectrometry (AAS), ion selective electrodes (ISE), and flame photometry. In addition, for the detection of HTM (heavy and transition metal), colorimetric sensors have also gained interest. The colorimetric sensors have considerable advantages over other molecular sensors because they do not require the use of costly equipment such as spectrophotometers, ISE, or cyclic voltameters. So, to develop simple-to-use and naked-eye diagnostic tool, great efforts have been made for the design and synthesis of selective chromogenic sensors for Hg{sup 2+}.

A dansyl group modified SBA-15 INHIBIT logic gate with [Hg2+ and Cl-] or [Hg2+ and Br-] as inputs

Science.gov (United States)

Wang, Xiaoyu; Yang, Honglei

2013-07-01

We developed a SBA-15-based INHIBIT logic gate (DA-SBA-15) which was prepared by covalent immobilization of a dansylamide derivative into the channels of the mesoporous silica material (SBA-15) via (3-aminopropyl)triethoxysilane (APTES) groups. A series of characteristic results proved that the fluorescent ligand was successfully grafted into the mesopores of SBA-15. The fluorescent characterization revealed excellent selectivity of DA-SBA-15 to the Hg2+ ion. Moreover, DA-SBA-15 can be considered as a selective fluorescent probe for Cl- and Br-. The fluorescent changes of DA-SBA-15 upon the addition of ions (Hg2+, Cl- and Br-) were utilized as an INH logic gate at the molecular level, using [Hg2+ and Cl-] or [Hg2+ and Br-] as chemical inputs and the fluorescence intensity signal as output.

Using Simple Science to Influence Corporate Responsibility—A Lesson from Mercury (Hg)

Science.gov (United States)

Filippelli, G. M.

2016-12-01

Mercury (Hg) is a powerful neurotoxin with wide environmental distribution. Typical population exposure to Hg comes from fish consumption, with fish being the final ecological endpoint of Hg magnification after a series of biogeochemical processes. The emission of Hg from coal-fired power plants has been strongly implicated as a key source of environmental Hg, and thus the target for various public policy initiatives in the US and abroad. We conducted a study of Hg distribution in surface soils over a broad area of central Indiana (US) to understand the major sources of Hg to local fish, and to assess the potential role of policy compliance in reducing Hg. We found a plume-like distribution pattern for soil Hg, with values exceeding 400 ppb Hg in the heart of the plume, and reducing to background concentration of about 30 ppb outside of the plume. The plume covered hundreds of square kilometers, was centered directly over the downtown area of Indianapolis (a city of roughly 1 million inhabitants), and could be roughly backtracked to a source in the southwest corner of the city, coincident with a large coal-fired utility plant that has the highest reported emissions of Hg in the area. Evidence of this link between a local source of Hg and net Hg deposition, with related implications for Hg runoff to local stream, biomagnification to fish, and fish consumption advisories was reported in regional newspapers and eventually published in scientific journals. But importantly, these findings were used by an NGO (the Beyond Coal campaign by Indiana branch of the Sierra Club) at a critical time to influence a decision by the owner of the power plant of whether to comply with the Hg policy rule by either adding higher technology scrubbing technologies to the plant or simply to convert the plant over to natural gas as the fuel source (a costlier choice upfront). The utility chose the latter option, and with the permanent elimination of Hg emissions, the net measurable effects

Mass loading of Hg in the Monte Amiata mining district, Southern Tuscany (Italy)

OpenAIRE

Rimondi V.; Costagliola P.; Gray J. E.; Lattanzi P.; Nannucci M.; Salvadori A.; Vaselli O.

2013-01-01

Mercury (Hg) transport in natural environments is of concern because Hg bioaccumulates in the food web. Particularly methyl-Hg is the form of Hg of major concern as it is highly toxic to humans and is ingested through food consumption, dominantly fish. Quantification of Hg mass loads in watersheds draining Hg mine districts allows (1) the identification of sources of contamination, (2) the evaluation of the effect of Hg on the environment, and (3) the identification of processes affecting Hg ...

Mercury Retention and Accumulation by Plants at the Abandoned New Idria Mine Site - a Preliminary micro-XRF and micro-XRD Study

Science.gov (United States)

Siebner, H.; Webb, S. M.; Brown, G. E.

2008-12-01

Due to its high toxicity and increasing levels in ecosystems, Hg pollution has become a serious global problem. A lot of research has been conducted with regard to Hg biogeochemical cycles in aquatic systems. Much less is known about terrestrial Hg-cycles in general and in plants specifically. Plants play an important role in these cycles; they are known to be an important sink for both atmospheric and soil Hg, the vegetative cover significantly influences soil erosion and migration of contaminants into aquatic systems. However, the processes involved in the interactions of Hg with plants and plants products are poorly studied. Information concerning the interaction of Hg in plants at the molecular level is sparse. The present study is intended to provide new information on Hg retention, translocation, and accumulation in plants associated with mercury mine wastes in central California. We present here preliminary results of Hg distribution in root and leave samples, taken from different plant species, which have adapted to the hostile environment at the New Idria site. Samples were taken at two locations that differ in water acidity and flooding regime. The distribution of Hg appears to be affected by plant species, growing conditions, and development stage. Micro-XRF images of root sections show that Hg is mainly associated with Fe plaque at the outer surfaces and epidermis, but is distributed differently in roots of the two plants. Micro-XRD showed evidence for mineralogical changes in the plaque through the sections. Mercury in leaves was found to be highly diffuse in its distribution, and is not associated with Fe-rich particles attached to the outer surface of the leaf. This finding implies that Hg is assimilated in the leaf tissue. Further examination of Fe plaque characteristics and associated Hg, as well as Hg speciation in the different organs of these plants, is being conducted in our lab.

Mechanism of Hg(II) Immobilization in Sediments by Sulfate-Cement Amendment.

Science.gov (United States)

Serrano, Susana; Vlassopoulos, Dimitri; O'Day, Peggy A

2016-04-01

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO 4 amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L III - and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 . 26H 2 O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20-25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg-Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg-Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a

Food preferences and Hg distribution in Chelonia mydas assessed by stable isotopes

International Nuclear Information System (INIS)

Bezerra, M.F.; Lacerda, L.D.; Rezende, C.E.; Franco, M.A.L.; Almeida, M.G.; Macêdo, G.R.; Pires, T.T.; Rostán, G.; Lopez, G.G.

2015-01-01

Mercury (Hg) is a highly toxic pollutant that poses in risk several marine animals, including green turtles (Chelonia mydas). Green turtles are globally endangered sea turtle species that occurs in Brazilian coastal waters as a number of life stage classes (i.e., foraging juveniles and nesting adults). We assessed total Hg concentrations and isotopic signatures ("1"3C and "1"5N) in muscle, kidney, liver and scute of juvenile green turtles and their food items from two foraging grounds with different urban and industrial development. We found similar food preferences in specimens from both areas but variable Hg levels in tissues reflecting the influence of local Hg backgrounds in food items. Some juvenile green turtles from the highly industrialized foraging ground presented liver Hg levels among the highest ever reported for this species. Our results suggest that juvenile foraging green turtles are exposed to Hg burdens from locally anthropogenic activities in coastal areas. - Highlights: • We report major diet items for foraging green turtles from northeastern Brazil. • We compare Hg levels between industrialized and relatively pristine foraging grounds. • High local Hg background levels increase Hg exposure in foraging green turtles. • Even an herbivore diet could result in high tissue Hg concentrations. - Hg levels in scutes of foraging green turtles correlated with internal Hg burdens and were influenced by local sources of pollution in two tropical foraging grounds.

Assessment of soil contamination by potentially toxic trace elements (PTSD) (As, Cd, Cu, Hg, Pb, Zn) in a lower plain of the Hron River according to Law no. 219/2008 Coll., by geo-accumulation index, anthropogenic factor and Tomlinson index; Zhodnotenie kontaminacie pod potencialne toxickymi stopovymi prvkami (PTSP) (As, Cd, Cu, Hg, Pb, Zn) v dolnej casti nivy Hrona podla zakona c. 219/2008 Z.z., indexu geoakumulacie, antropogenneho faktora a Tomlinsonovho indexu

Energy Technology Data Exchange (ETDEWEB)

Hlodak, M [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Ustav laboratorneho vyskumu geomaterialov, 84215 Bratislava (Slovakia)

2012-04-25

Soil contamination by different PTSD may have different geogenic and anthropogenic origin and occurs in all countries of the world. The aim of this paper is to evaluate the soils contamination of a lower plain of the Hron River. This paper used the results of the thesis Soil contamination of the Hron River floodplain by trace elements (As, Cd, Cu, Hg, Pb, Zn) [1]. Soil contamination was evaluated by: Act. 219/2008 Coll. on the protection and use of agricultural land, by anthropogenic factor (AF), geo-accumulation index (IgeoE) and Tomlinson index - the index of the pollution load (PLI). (author)

Nuclear radiation detected optical pumping of neutron deficient Hg isotopes

International Nuclear Information System (INIS)

Bonn, J.

1975-01-01

The extension of the Nuclear Radiation Detected Optical Pumping method to mass-separated samples of isotopes far off stability is presented for a series of light Hg isotopes produced at the ISOLDE facility at CERN. The isotope under investigation is transferred by an automatic transfer system into the optical pumping apparatus. Zeeman scanning of an isotopically pure Hg spectral lamp is used to reach energetic coincidence with the hyperfine structure components of the 6s 2 1 S 0 -6s6p 3 P 1 (lambda = 2537 A) resonance line of the investigated isotope and the Hg lamp. The orientation build up by optical pumping is monitored via the asymmetry or anisotropy of the nuclear radiation. Nuclear spins, magnetic moments, electric quadrupole moments and isotopic shift are obtained for 181 Hg- 191 Hg using the β-asymmetry as detector. The extension of the method using the γ-anisotropy is discussed and measurements on 193 Hg are presented. (orig./HK)

Accumulation of trace metals by aquatic macrophytes and their possible use in phytoremediation techniques

Directory of Open Access Journals (Sweden)

Michaela Hillermannová

2008-01-01

Full Text Available The aim of the performed research was to obtain knowledge on the ability of aquatic plants naturally growing at a site to absorb trace metals contained in bottom sediments and surface water. Furthermore, we compared differences in the accumulation of trace metals by the individual groups of aquatic plants (submerged and emergent and assessed a possible use of the individual plant species in phytoremediation techniques. Representative samples of water, sediments and aquatic macrophytes were taken from three anthropogenically loaded streams in six monitoring cycles in several collection profiles differing in the distance from a source of contamination. The samples were analysed for the total content of selected trace metals (As, Cd, Pb, Al, Hg, Zn, Fe, Mn, Cr, Ni and Cu. For comparison, one profile at an unloaded site was sampled as well. The obtained results were subjected to multivariate statistical analysis of data. Increased contents of Fe, Al, Mn, Cr and Zn were detected in sediments and plant biomass at loaded sites, namely 2–3× higher than at the comparing site. The contents of metals in surface water samples were altogether below the detection limit of the analytical method. When evaluating the individual plant species, we can state that the lowest contents of metals were detected in shore species (reed canary grass Phalaroides arundinacea, wood club-rush Scirpus silvaticus and red dock Rumex aquaticus; plant species growing in the very water current (water star-wort Callitriche sp. and flote-grass Glyceria fluitans exhibited mean contents of metals. In species forming mats (Fontinalis antipyretica and Cladophora sp., these contents were several times higher as compared to the previous species. The results of the performed research show that one of important factors, which influence the accumulation of trace metals in plants, is their ecological group (emergent – submerged affiliation and the species classification within this group

High spin structures in 194Hg

International Nuclear Information System (INIS)

Fotiades, N.; Vlastou, R.; Serris, M.; Sharpey-Schafer, J.F.; Fallon, P.; Riley, M.A.; Clark, R.M.; Hauschild, K.; Wadsworth, R.

1996-01-01

High spin states in the isotope 194 Hg were populated using the 150 Nd( 48 Ca,4n) reaction at a beam energy of 213 MeV. The analysis of γ-γ coincidences has revealed two new structures at excitation energies above 6 MeV and at moderate spin. The two structures are a manifestation of the deviation of nucleus from the collective rotation which dominates its lower excitation behaviour. A comparison with similar structures in the neighbouring Hg isotopes is also attempted. (orig.)

Tracing anthropogenic Hg and Pb input using stable Hg and Pb isotope ratios in sediments of the central Portuguese Margin

NARCIS (Netherlands)

Mil-Holmens, M.; Blum, J.; Canário, J.; Caetano, M.; Costa, A.M.; Lebreiro, S.M.; Trancoso, M.; Richter, T.O.; de Stigter, H.; Johnson, M.; Branco, V.; Cesário, R.; Mouro, F.; Mateus, M.; Boer, W.; Melo, Z.

2013-01-01

Three short marine sediment cores from the Cascais Submarine Canyon (CSC; cores 252-32 and 252-35) and the Estremadura Spur (core 252-16) on the central Portuguese Margin were analysed for Hg, Pb, Al, and Mn concentrations, and both Pb and Hg stable isotope compositions, in order to reconstruct

Activation of the Hg-C Bond of Methylmercury by [S2]-Donor Ligands.

Science.gov (United States)

Karri, Ramesh; Banerjee, Mainak; Chalana, Ashish; Jha, Kunal Kumar; Roy, Gouriprasanna

2017-10-16

Here we report that [S 2 ]-donor ligands Bmm OH , Bmm Me , and Bme Me bind rapidly and reversibly to the mercury centers of organomercurials, RHgX, and facilitate the cleavage of Hg-C bonds of RHgX to produce stable tetracoordinated Hg(II) complexes and R 2 Hg. Significantly, the rate of cleavage of Hg-C bonds depends critically on the X group of RHgX (X = BF 4 - , Cl - , I - ) and the [S 2 ]-donor ligands used to induce the Hg-C bonds. For instance, the initial rate of cleavage of the Hg-C bond of MeHgI induced by Bme Me is almost 2-fold higher than the initial rate obtained by Bmm OH or Bmm Me , indicating that the spacer between the two imidazole rings of [S 2 ]-donor ligands plays a significant role here in the cleavage of Hg-C bonds. Surprisingly, we noticed that the initial rate of cleavage of the Hg-C bond of MeHgI induced by Bme Me (or Bmm Me ) is almost 10-fold and 100-fold faster than the cleavage of Hg-C bonds of MeHgCl and [MeHg]BF 4 respectively, under identical reaction conditions, suggesting that the Hg-C bond of [MeHg]BF 4 is highly inert at room temperature (21 °C). We also show here that the nature of the final stable cleaved products, i.e. Hg(II) complexes, depends on the X group of RHgX and the [S 2 ]-donor ligands. For instance, the reaction of Bmm Me with MeHgCl (1:1 molar ratio) afforded the formation of the 16-membered metallacyclic dinuclear mercury compound (Bmm Me ) 2 Hg 2 Cl 4 , in which the two Cl atoms are located inside the ring, whereas due to the large size of the I atom, a similar reaction with MeHgI yielded polymeric [(Bmm Me ) 2 HgI 2 ] m ·(MeHgI) n . However, the treatment of Bmm Me with ionic [RHg]BF 4 led to the formation of the tetrathione-coordinated mononuclear mercury compound [(Bmm Me ) 2 Hg](BF 4 ) 2 , where BF 4 - serves as a counteranion.

40 CFR 60.4141 - Timing requirements for Hg allowance allocations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Timing requirements for Hg allowance... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Allocations § 60.4141 Timing requirements for Hg allowance allocations. (a) By November 17, 2006, the permitting authority will submit to...

BIOADSORPSI Hg(II OLEH PATI SAGU TAUT SILANG FOSFAT [Bioadsorption of Hg(II by Crosslinked Sago Starch Phosphate

Directory of Open Access Journals (Sweden)

Sri Sugiarti2

2012-12-01

Full Text Available Crosslinked-sago-starch-phosphate (SgP has been successfully synthesized from native sago starch (Sg and Na2HPO4-NaH2PO4 in an acidic condition. The compound was designed as bioadsorbent for removing Hg(II inside human digestion tract as shown by in vitro test. The bioadsorption followed pseudo-second order of reaction kinetic and Freundlich equation as chemisorption. As a result, 21% of Hg(II was removed at pH of 6.80 and reached the isothermal equilibrium of the bioadsorption at pH of 5.80 and 8.60 for 29.95% and 31.39%, respectively. The result showed that SgP is more feasible than activated carbon to be used as bioadsorbent in removing Hg(II in human digestion tract as proved by in vitro system.

48 CFR 752.231-71 - Salary supplements for HG employees.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Salary supplements for HG....231-71 Salary supplements for HG employees. As prescribed in 731.205-71, for use in all contracts with... sub-contracts. Salary Supplements for HG Employees (OCT 1998) (a) Salary supplements are payments made...

Adsorption of Hg on lunar samples

International Nuclear Information System (INIS)

Reed, G.W. Jr.; Jovanovic, S.

1985-01-01

Understanding the presence, migration mechanisms and trapping of indigneous gases and volatiles on the moon is the objective of this study. The rare gases Ar and Xe and highly volatile Hg 0 and Br 0 (and/or their compounds) have been determined to be present in the lunar regolith. Evidence for these elements in the moon was recently reviewed. Studies of the sorption behavior of Xe on lunar material have been carried out. We report here preliminary results of a study designed to rationalize the behavior of Hg in lunar material

40 CFR 60.4123 - Hg budget permit contents and term.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Hg budget permit contents and term. 60... Coal-Fired Electric Steam Generating Units Permits § 60.4123 Hg budget permit contents and term. (a) Each Hg Budget permit will contain, in a format prescribed by the permitting authority, all elements...

Genetic Polymorphisms in Glutathione (GSH- Related Genes Affect the Plasmatic Hg/Whole Blood Hg Partitioning and the Distribution between Inorganic and Methylmercury Levels in Plasma Collected from a Fish-Eating Population

Directory of Open Access Journals (Sweden)

Andréia Ávila Soares de Oliveira

2014-01-01

Full Text Available This study aims to evaluate the effects of polymorphisms in glutathione (GSH- related genes (GSTM1, GSTT1, GSTP1, GCLM, and GCLC in the distribution of Hg in the blood compartments in humans exposed to methylmercury (MeHg. Subjects (n=88, exposed to MeHg from fish consumption, were enrolled in the study. Hg species in the plasma compartment were determined by LC-ICP-MS, whereas genotyping was performed by PCR assays. Mean total Hg levels in plasma (THgP and whole blood (THgB were 10±4.2 and 37±21, whereas mean evels of plasmatic MeHg (MeHgP, inorganic Hg (IHgP, and HgP/HgB were 4.3±2.9, 5.8±2.3 µg/L, and 0.33±0.15, respectively. GSTM1 and GCLC polymorphisms influence THgP and MeHgP (multivariate analyses, P<0.050. Null homozygotes for GSTM1 showed higher THgP and MeHgP levels compared to subjects with GSTM1 (THgP β=0.22, P=0.035; MeHgP β=0.30, P=0.050 and persons carrying at least one T allele for GCLC had significant higher MeHgP (β=0.59, P=0.046. Also, polymorphic GCLM subjects had lower THgP/THgB than those with the nonvariant genotype. Taken together, data of this study suggest that GSH-related polymorphisms may change the metabolism of MeHg by modifying the distribution of mercury species iin plasma compartment and the HgP/HgB partitioning.

Multivariate characterization of elements accumulated in King Bolete Boletus edulis mushroom at lowland and high mountain regions.

Science.gov (United States)

Falandysz, J; Kunito, T; Kubota, R; Bielawski, L; Frankowska, A; Falandysz, Justyna J; Tanabe, S

2008-12-01

Based on ICP-MS, ICP-OES, HG-AAS, CV-AAS and elementary instrumental analysis of King Bolete collected from four sites of different soil bedrock geochemistry considered could be as mushroom abundant in certain elements. King's Bolete fruiting bodies are very rich in K (> 20 mg/g dry weight), rich in Ca, Mg, Na, Rb and Zn (> 100 microg/g dw), and relatively also rich in Ag, Cd, Cs, Cu, Fe, Mn and Se (> 10 microg/g dw). The caps of King Bolete when compared to stipes around two-to three-fold more abundant are in Ag, Cd, Cs, Cu, Hg, K, Mg, Mo, N, Rb, Se and Zn. King Bolete collected at the lowland and mountain sites showed Ag, Ba, Co, Cr, Hg, K, Mg, Mn, Mo and Na in caps in comparable concentrations, and specimens from the mountain areas accumulated more Cd and Sb. Elements such as Al, Pb and Rb occurred at relatively elevated concentration in King Bolete picked up at the metal ores-rich region of the Sudety Mountains. Because of high bioconcentration potential King Bolete at the background sites accumulate in fruiting bodies great concentrations of problematic elements such as Cd, Pb and Hg, i.e. up to nearly 20, 3 and 5 microg/g dw, on the average, respectively. The interdependence among determined mineral elements examined were using the principal components analysis (PCA) method. The PCA explained 56% of the total variance. The metals tend to cluster together (Ba, Cd, Cs, Cr, Ga, Rb, Se, Sr and V; K and Mg; Cu and Mo). The results provided useful environmental and nutritional background level information on 26 minerals as the composition of King Bolete from the sites of different bedrock soil geochemistry.

Distribution and accumulation of Cd, Cu, Hg, Pb and Zn in the surface sediments of El Tobari Lagoon, central-East Gulf of California: An ecosystem associated with agriculture and aquaculture activities.

Science.gov (United States)

Jara-Marini, M E; Tapia-Alcaraz, J N; Dumer-Gutiérrez, J A; García-Rico, L; García-Hernández, J; Páez-Osuna, F

2013-01-01

The purpose of this research is to provide a comprehensive assessment of the concentration levels and spatial variability of cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb) and zinc (Zn) in El Tobari Lagoon in surface sediments during two seasons for several geochemical variables that could explain the observed heavy metal variability. Seventy-two surface sediments samples were collected in 12 different sites of the El Tobari Lagoon. Sediment samples were dried and subjected to acid extraction using a microwave system and five metals (Cd, Cu, Hg, Pb and Zn) were measured using atomic adsorption spectrometry. A certificate sediment material and blanks were used as quality control purposes. The enrichment factor (EF) and the index of geoaccumulation (Igeo) were calculated as index of metals contamination for the sediments, using aluminum as the conservative element. The five metals examined in sediments from El Tobari Lagoon exhibited a linear correlation with Al as result of the large specific surface areas of these sediment components and the chemical affinities between them. The metals contents in sites of the El Tobari Lagoon were variable, and Cd, Cu and Hg presented a seasonal behavior. The enrichment factor and index of geoaccumulation analysis indicated that Cd and Hg exhibited a certain extent (EF for Cd ranged from 4.10 to 10.29; EF for Hg ranged from 2.77 to 12.89) of anthropogenic pollution, while Cu showed sporadic (EF ranged from 0.43 to 2.54) anthropogenic contamination. The highest concentrations of Cd, Cu and Hg were found in the sites that regularly received discharge effluents from agriculture and aquaculture.

Design principles for HgTe based topological insulator devices

Science.gov (United States)

Sengupta, Parijat; Kubis, Tillmann; Tan, Yaohua; Povolotskyi, Michael; Klimeck, Gerhard

2013-07-01

The topological insulator properties of CdTe/HgTe/CdTe quantum wells are theoretically studied. The CdTe/HgTe/CdTe quantum well behaves as a topological insulator beyond a critical well width dimension. It is shown that if the barrier (CdTe) and well-region (HgTe) are altered by replacing them with the alloy CdxHg1-xTe of various stoichiometries, the critical width can be changed. The critical quantum well width is shown to depend on temperature, applied stress, growth directions, and external electric fields. Based on these results, a novel device concept is proposed that allows to switch between a normal semiconducting and topological insulator state through application of moderate external electric fields.

Kinetics and mechanism of jack bean urease inhibition by Hg2+

Directory of Open Access Journals (Sweden)

Du Nana

2012-12-01

Full Text Available Abstract Background Jack bean urease (EC 3.5.1.5 is a metalloenzyme, which catalyzes the hydrolysis of urea to produce ammonia and carbon dioxide. The heavy metal ions are common inhibitors to control the rate of the enzymatic urea hydrolysis, which take the Hg2+ as the representative. Hg2+ affects the enzyme activity causing loss of the biological function of the enzyme, which threatens the survival of many microorganism and plants. However, inhibitory kinetics of urease by the low concentration Hg2+ has not been explored fully. In this study, the inhibitory effect of the low concentration Hg2+ on jack bean urease was investigated in order to elucidate the mechanism of Hg2+ inhibition. Results According to the kinetic parameters for the enzyme obtained from Lineweaver–Burk plot, it is shown that the Km is equal to 4.6±0.3 mM and Vm is equal to 29.8±1.7 μmol NH3/min mg. The results show that the inhibition of jack bean urease by Hg2+ at low concentration is a reversible reaction. Equilibrium constants have been determined for Hg2+ binding with the enzyme or the enzyme-substrate complexes (Ki =0.012 μM. The results show that the Hg2+ is a noncompetitive inhibitor. In addition, the kinetics of enzyme inhibition by the low concentration Hg2+ has been studied using the kinetic method of the substrate reaction. The results suggest that the enzyme first reversibly and quickly binds Hg2+ and then undergoes a slow reversible course to inactivation. Furthermore, the rate constant of the forward reactions (k+0 is much larger than the rate constant of the reverse reactions (k-0. By combining with the fact that the enzyme activity is almost completely lost at high concentration, the enzyme is completely inactivated when the Hg2+ concentration is high enough. Conclusions These results suggest that Hg2+ has great impacts on the urease activity and the established inhibition kinetics model is suitable.

Accumulation, transfer, and potential sources of mercury in the soil-wheat system under field conditions over the Loess Plateau, northwest China

International Nuclear Information System (INIS)

Wang, Shengli; Nan, Zhongren; Prete, Daniel; Ma, Jianmin; Liao, Qin; Zhang, Qian

2016-01-01

There is limited information on accumulation, transfer, and source of mercury in wheats under field conditions over the Loess Plateau, northwest China. The present study collected 26 pairs of topsoil and whole wheat samples (roots, stems, leaves, shells, and grains) from Dongdagou stream watershed and upper Xidagou stream watershed, Baiyin City, northwest China. Hg concentrations from these samples were used to identify their relationships with soil properties, interactions with other metals, localization of Hg in the different wheat tissues, bio-concentration and transfer of Hg, and major sources of Hg in wheat. Results show that Hg levels in 11 out of 26 sampled soils (42.3% of soil samples) exceeded Hg limit of grade II soil environmental quality standards in China (1.0 mg·kg"− "1). Likewise, it was also found that Hg in over 50% of wheat grain samples reached or exceeded the maximum permissible food safety levels (0.02 mg·kg"− "1) according to the General Standard of Contaminants in Food in China (GB 2762-2012). The spatial distribution pattern of Hg in wheats grains was different from that in the sampled soils. Hg concentrations in different wheat tissues were highest in roots, followed by leaves, stalks, shells, and grains, respectively. Bio-concentration factors (BCF) of Hg in almost all grains samples were one or two orders of magnitude lower than that in roots, except for two wheat samples. The translocation factors (TF) of Hg in wheat tissues on average were leaves > stems > shells > grains. The spatial distribution of Hg and its correlation with other heavy metal detected simultaneously in the soil samples suggested that the Hg soil contamination was probably caused by past sewage irrigation practices and atmospheric deposition. Correlation analysis revealed that the principle source of Hg in wheat roots was very likely from Hg contaminated soils. - Highlights: • Hg concentrations in wheats and corresponding soils from loess plateau, northwest

Accumulation, transfer, and potential sources of mercury in the soil-wheat system under field conditions over the Loess Plateau, northwest China

Energy Technology Data Exchange (ETDEWEB)

Wang, Shengli [Key Laboratory for Environmental Pollution Prediction and Control, Gansu Province, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Western China' s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Nan, Zhongren, E-mail: nanzhongren@lzu.edu.cn [Key Laboratory for Environmental Pollution Prediction and Control, Gansu Province, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Western China' s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Prete, Daniel [Department of Chemistry and Biology, Ryerson University, Toronto M5B 2K3 (Canada); Ma, Jianmin; Liao, Qin; Zhang, Qian [Key Laboratory for Environmental Pollution Prediction and Control, Gansu Province, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China)

2016-10-15

There is limited information on accumulation, transfer, and source of mercury in wheats under field conditions over the Loess Plateau, northwest China. The present study collected 26 pairs of topsoil and whole wheat samples (roots, stems, leaves, shells, and grains) from Dongdagou stream watershed and upper Xidagou stream watershed, Baiyin City, northwest China. Hg concentrations from these samples were used to identify their relationships with soil properties, interactions with other metals, localization of Hg in the different wheat tissues, bio-concentration and transfer of Hg, and major sources of Hg in wheat. Results show that Hg levels in 11 out of 26 sampled soils (42.3% of soil samples) exceeded Hg limit of grade II soil environmental quality standards in China (1.0 mg·kg{sup −} {sup 1}). Likewise, it was also found that Hg in over 50% of wheat grain samples reached or exceeded the maximum permissible food safety levels (0.02 mg·kg{sup −} {sup 1}) according to the General Standard of Contaminants in Food in China (GB 2762-2012). The spatial distribution pattern of Hg in wheats grains was different from that in the sampled soils. Hg concentrations in different wheat tissues were highest in roots, followed by leaves, stalks, shells, and grains, respectively. Bio-concentration factors (BCF) of Hg in almost all grains samples were one or two orders of magnitude lower than that in roots, except for two wheat samples. The translocation factors (TF) of Hg in wheat tissues on average were leaves > stems > shells > grains. The spatial distribution of Hg and its correlation with other heavy metal detected simultaneously in the soil samples suggested that the Hg soil contamination was probably caused by past sewage irrigation practices and atmospheric deposition. Correlation analysis revealed that the principle source of Hg in wheat roots was very likely from Hg contaminated soils. - Highlights: • Hg concentrations in wheats and corresponding soils from loess

46 CFR 53.05-3 - Materials (modifies HG-401.2).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Materials (modifies HG-401.2). 53.05-3 Section 53.05-3... Pressure Relieving Devices (Article 4) § 53.05-3 Materials (modifies HG-401.2). Materials for valves must be in accordance with HG-401.2 of section IV of the ASME Boiler and Pressure Vessel Code...

Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques.

Science.gov (United States)

Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Göttlicher, Jörg; Denecke, Melissa A; Mangold, Stefan; Ruggiero, Pacifico

2010-08-01

Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg(-1). Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as mu-XRF, mu-XRD and mu-XANES were necessary to solve bulk Hg speciation, in both soil fractions soil samples were metacinnabar (beta-HgS), cinnabar (alpha-HgS), corderoite (Hg(3)S(2)Cl(2)), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. Copyright 2010 Elsevier Ltd. All rights reserved.

Chemical doping and improved flux pinning in Hg-based superconductors

International Nuclear Information System (INIS)

Kishio, K.; Shimoyama, J.; Yoshikawa, A.; Kitazawa, K.

1996-01-01

Chemical doping of a small amount (0.02∼0.3) of rhenium (Re) ion into HgBa 2 Ca n-1 Cu n O y (n=1∼4) has been studied. The flux pinning strength in these Hg-based superconductors is significantly enhanced compared to the undoped parent materials. Neutron diffraction analysis of representative samples (n=3) revealed that Re partially substitutes the Hg-site with octahedrally fully coordinated oxygen atoms, giving rise to the stabilization of Hg(Re)O layer and reduction of this blocking layer thickness. Associated with the expected hybridization of Re-5d and O-2p orbitals and possible metallization of the Hg(Re)O layer, the improved flux pinning behavior is considered to be caused by the decrease of the electromagnetic anisotropy and the enhanced interlayer superconducting coupling strength

Theoretical studies on the interaction and dynamics in the colisional systems Hg+Li,Na,P and Ar*(4s3P2,0)+Hg,H

International Nuclear Information System (INIS)

Thiel, L.

2004-01-01

The central aim of this work is the detailed theoretical characterization of the autoionization process in collisions of metastable argon atoms with mercury and hydrogen atoms, Ar * (4s 3 P 2,0 ) + Hg and Ar * (4s 3 P 2,0 ) + H(1s). The autoionization process in the collision complexes Ar * (4s 3 P 2,0 ) + Hg und Ar * (4s 3 P 2,0 ) + H(1s) was investigated using the local complex potential approximation. Within this approach the entrance channel is described by a complex resonance potential whose imaginary part - the socalled autoionization width describes the ionization probability as a function of the internuclear distance. For both investigated systems, this work presents the first ab initio treatment of the autoionization process. In the collision complex Ar * + Hg, the asymptote of the entrance channel lies energetically above the asymptote of the exit channel Ar + Hg + . Both Penning ionization (PI) Ar * + Hg → Ar + Hg + + e - and associative ionization (AI) Ar * + Hg → ArHg + + e - are possible at thermal collision energies. The resonance potential and the autoionization width which describe the entrance channel were determined in MRCI calculations in which the resonance state was de- fined through Feshbach projection based on orbital occupancy. Taking the spin-orbit interaction in the Ar + core into account, the calculated complex potentials are able to reproduce the available experimental data such as the absolute ionization cross sections, the collision energy dependence of the relative cross sections for Penning and assoziative ionization and the electron energy spectra. (orig.)

Uptake of Hg2+ by picocyanobacteria in natural water from four Andean lakes

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Diéguez M.C.

2014-07-01

Full Text Available In lake food webs, planktonic bacteria and algae represent the greatest bioconcentration step for Hg2+ and monomethyl-Hg (MeHg. As they are the most abundant organisms in planktonic trophic webs and also the main food resource for herbivorous plankton, they can mobilize large amounts of Hg to higher trophic levels. In Andean Patagonian lakes (Argentina, dissolved organic matter (DOM concentration and character, coupled with photo-reactions, play a central role in the complexation of Hg2+ in the water column and can even regulate the uptake of Hg2+ by planktonic algae. In this investigation we evaluated the DOM character of natural waters (NW from four Andean lakes and studied its influence on the uptake of 197Hg2+ in a strain of the picocyanobacteria Synechococcus by using Hg2+ labeled with 197Hg2+. The uptake of radiolabeled Hg2+ by Synechococcus showed different magnitude in NW of lakes Moreno, El Trébol, Morenito and Escondido. Increasing lake DOM concentration reduced the bioavailability of Hg2+ as indicated by the lower uptakes rates found in NW with higher complexity and concentration of the DOM pool. Uptakes of Hg2+ by this picocyanobacteria contrasted among NW from pelagic (surface and bottom and littoral compartments of Lake Escondido which suggest that the entry of this metal may be highly variable even in the same environment. The study of the uptake of radiolabeled Hg2+ in a set of dilutions of NW from Lake Escondido demonstrated that the bioavailability of Hg2+ decrease with increasing DOM concentration.

Synthesis, crystal and electronic structures and optical properties of (HIm)₂ Hg₃Cl₈ and (HIm)HgI₃ (HIm = imidazolium)

Energy Technology Data Exchange (ETDEWEB)

Nhalil, Hariharan [Univ. of Oklahoma, Norman, OK (United States). Dept. of Chemistry and Biochemistry; Whiteside, Vincent R. [Univ. of Oklahoma, Norman, OK (United States). Homer L. Dodge Dept. of Physics & Astronomy; Sellers, Ian R. [Univ. of Oklahoma, Norman, OK (United States). Homer L. Dodge Dept. of Physics & Astronomy; Ming, Wenmei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Du, Mao-Hua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Saparov, Bayrammurad [Univ. of Oklahoma, Norman, OK (United States). Dept. of Chemistry and Biochemistry

2017-11-22

Here, we report synthesis, crystal and electronic structures, and optical properties of two new Hg-based zero-dimensional hybrid organic-inorganic halides (HIm)2Hg3Cl8 and (HIm)HgI3 (HIm = imidazolium). (HIm)₂Hg₃Cl₈ crystallizes in the triclinic P-1 space group with a pseudo-layered structure made of organic imidazolium cation layers and anionic inorganic layers containing [Hg₂Cl₆]^2- units and linear [HgCl₂]⁰ molecules. (HIm)HgI₃ crystallizes in the monoclinic P2₁/c space group featuring anionic [HgI₃]- units that are surrounded by imidazolium cations. Based on density functional theory calculations, (HIm)₂Hg₃Cl₈ has an indirect band gap, whereas (HIm)HgI₃ has a direct band gap with the measured onsets of optical absorption at 3.43 and 2.63 eV, respectively. (HIm)₂Hg₃Cl₈ and (HIm)HgI₃ are broadband light emitters with broad photoluminescence peaks centered at 548 nm (2.26 eV) and 582 nm (2.13 eV), respectively. In conclusion, following the crystal and electronic structure considerations, the PL peaks are assigned to self-trapped excitons.

Differences in grain ultrastructure, phytochemical and proteomic profiles between the two contrasting grain Cd-accumulation barley genotypes.

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Hongyan Sun

Full Text Available To reveal grain physio-chemical and proteomic differences between two barley genotypes, Zhenong8 and W6nk2 of high- and low-grain-Cd-accumulation, grain profiles of ultrastructure, amino acid and proteins were compared. Results showed that W6nk2 possesses significantly lower protein content, with hordein depicting the greatest genotypic difference, compared with Zhenong8, and lower amino acid contents with especially lower proportion of Glu, Tyr, Phe and Pro. Both scanning and transmission electron microscopy observation declared that the size of A-type starch molecule in W6nk2 was considerably larger than that of Zhenong8. Grains of Zhenong8 exhibited more protein-rich deposits around starch granules, with some A-type granules having surface pits. Seventeen proteins were identified in grains, using 2-DE coupled with mass spectrometry, with higher expression in Zhenong8 than that in W6nk2; including z-type serpin, serpin-Z7 and alpha-amylase/trypsin inhibitor CM, carbohydrate metabolism, protein synthesis and signal transduction related proteins. Twelve proteins were less expressed in Zhenong8 than that in W6nk2; including barley trypsin inhibitor chloroform/methanol-soluble protein (BTI-CMe2.1, BTI-CMe2.2, trypsin inhibitor, dehydroascorbate reductase (DHAR, pericentrin, dynein heavy chain and some antiviral related proteins. The data extend our understanding of mechanisms underlying Cd accumulation/tolerance and provides possible utilization of elite genetic resources in developing low-grain-Cd barley cultivars.

Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques

International Nuclear Information System (INIS)

Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Goettlicher, Joerg; Denecke, Melissa A.; Mangold, Stefan; Ruggiero, Pacifico

2010-01-01

Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg -1 . Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as μ-XRF, μ-XRD and μ-XANES were necessary to solve bulk Hg speciation, in both soil fractions 3 S 2 Cl 2 ), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 μm. No interaction among Hg-species and soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. - Direct mercury (Hg) speciation in chlor-alkali plant contaminated soils enabled the identification of potentially dangerous Hg-S/Cl amorphous species.

Mercury (Hg) burden in children: The impact of dental amalgam

International Nuclear Information System (INIS)

Al-Saleh, Iman; Al-Sedairi, Al anoud

2011-01-01

The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine (μg/g creatinine) and micrograms per liter (μg/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 μg/g creatinine versus 3.457 μg/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 μg/g (N = 97) for children with amalgam versus 0.242 μg/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 μg/g, N = 61) versus those with (0.163 μg/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and/or nephrotoxic effects of

Mercury (Hg) burden in children: The impact of dental amalgam

Energy Technology Data Exchange (ETDEWEB)

Al-Saleh, Iman, E-mail: iman@kfshrc.edu.sa [Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, PO Box: 3354, Riyadh 11211 (Saudi Arabia); Al-Sedairi, Al anoud [Department of Zoology, College of Science, King Saud University, PO Box: 24452, Riyadh 11495 (Saudi Arabia)

2011-07-15

The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine ({mu}g/g creatinine) and micrograms per liter ({mu}g/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 {mu}g/g creatinine versus 3.457 {mu}g/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 {mu}g/g (N = 97) for children with amalgam versus 0.242 {mu}g/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 {mu}g/g, N = 61) versus those with (0.163 {mu}g/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and

The new barium mercuride BaHg6 and ternary indium and gallium derivatives

International Nuclear Information System (INIS)

Wendorff, Marco; Röhr, Caroline

2013-01-01

Highlights: ► The new binary Hg-rich mercuride BaHg 6 crystallizes with a singular structure type. ► Ternary In substituted compounds are isotypic, whereas Ga substituted compounds are only structurally related. ► Structure relation to other Hg-rich alkali and alkaline earth mercurides. ► Discussion of covalent and metallic bonding aspects, as found by structure features and band structure calculations. - Abstract: The new binary barium mercuride BaHg 6 and the derived ternary indium and gallium containing compounds BaIn 1.2 Hg 4.8 and BaGa 0.8 Hg 5.2 were synthesized from melts of the elements, which were slowly cooled from 500 to 200 °C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The binary mercuride BaHg 6 (Pnma, a = 1338.9(3), b = 519.39(13), c = 1042.6(4) pm, Z = 4, R1 = 0.0885) and the isotypic indium substituted compound BaIn 1.2 Hg 4.8 as well as the structurally related gallium mercuride BaGa 0.8 Hg 5.2 (Cmcm, a = 729.77(7), b = 1910.1(2), c = 507.48(5) pm, Z = 4, R1 = 0.0606) crystallize with new structure types. Common features of both structures are planar nets of five- and eight-membered Hg rings, stacked perpendicular to the shortest axes. According to their lengths, the Hg–Hg bonds can be classified into three groups: strong, short ones (I, 285–292 pm), which are only found inside the nets, and longer distances (II), still carrying bond critical points, around 300 pm. Further contacts (III) serve to complete the coordination spheres of Hg/M (320–358 pm). The overall coordination numbers of Hg/M range from 10 to 13. The Ba cations are positioned in the centers of the octagons of the Hg/M nets, thus exhibiting a 5:8:5, i.e. 18, coordination by Hg/M atoms. DFT calculations of the electronic band structure of pure BaHg 6 and ordered models of the indium ( ′ BaInHg 5 ′ ) and the gallium ( ′ BaGaHg 5 ′ ) mercurides were performed using the FP-LAPW method. The calculated Bader charges

Phosphorus accumulation and spatial distribution in agricultural soils in Denmark

DEFF Research Database (Denmark)

Rubæk, Gitte Holton; Kristensen, Kristian; Olesen, S E

2013-01-01

Over the past century, phosphorus (P) has accumulated in Danish agricultural soils. We examined the soil P content and the degree of P saturation in acid oxalate (DPS) in 337 agricultural soil profiles and 32 soil profiles from deciduous forests sampled at 0–0.25, 0.25–0.50, 0.50–0.75 and 0...

Mercury induced oxidative stress, DNA damage, and activation of antioxidative system and Hsp70 induction in duckweed (Lemna minor).

Science.gov (United States)

Zhang, Tingting; Lu, Qianqian; Su, Chunlei; Yang, Yaru; Hu, Dan; Xu, Qinsong

2017-09-01

Mercury uptake and its effects on physiology, biochemistry and genomic stability were investigated in Lemna minor after 2 and 6d of exposure to 0-30μM Hg. The accumulation of Hg increased in a concentration- and duration-dependent manner, and was positively correlated with the leaf damage. Oxidative stress after Hg exposure was evidenced in L. minor by a significant decrease in photosynthetic pigments, an increase in malondialdehyde and lipoxygenase activities (total enzyme activity and isoenzymes activity). Fronds of L. minor exposed to Hg showed an induction of peroxidase, catalase, and ascorbate peroxidase activities (total enzyme activity and some isoenzymes activities). Exposure of L. minor to Hg reduced the activity (total enzyme activity and some isoenzymes activities) of glutathione reductase, and superoxide dismutase. Exposure to Hg produced a transient increase in the content of glutathione and ascorbic acid. The content of dehydroascorbate and oxidized glutathione in L. minor were high during the entire exposure period. Exposure of L. minor to Hg also caused the accumulation of proline and soluble sugars. The amplification of new bands and the absence of normal DNA amplicons in treated plants in the random amplified polymorphic DNA (RAPD) profile indicated that genomic template stability (GTS) was affected by Hg treatment. The accumulation of Hsp70 indicated the occurrence of a heat shock response at all Hg concentrations. These results suggest that L. minor plants were able to cope with Hg toxicity through the activation of various mechanisms involving enzymatic and non-enzymatic antioxidants, up-regulation of proline, and induction of Hsp70. Copyright © 2017 Elsevier Inc. All rights reserved.

Design of a peptidic turn with high affinity for HgII

DEFF Research Database (Denmark)

Pires, Sara; Habjanic, Jelena; Sezer, Murat

2012-01-01

A four amino acid peptide containing the ß-turn template dPro-Pro in the middle and two cysteines (Cys) in the terminal positions (CdPPC) has been synthesized and its mercury(II) coordination properties studied using different spectroscopic methods. The UV-vis, CD, (199m)Hg PAC, and Raman...... spectroscopic studies indicate the binding of Hg(II) to the two Cys, forming the dithiolatemercury(II) complex Hg(CdPPC). Electrospray ionization mass spectrometry corroborates the 1:1 complex formation. A log K = 40.0 was determined for the formation constant of the Hg(CdPPC) complex using competition...... potentiometric studies. Replacement of the dPro-Pro motif by a Pro-Pro unit generated a peptide (CPPC) capable of forming a similar species [Hg(CPPC)] but showing a lower affinity for Hg(II) (at least 3-3.5 orders of magnitude lower). The introduction of the dPro-Pro motif is crucial to induce the folding...

Mercury, zinc, and copper accumulation in mangrove sediments surrounding a large landfill in southeast Brazil

Energy Technology Data Exchange (ETDEWEB)

Machado, W.; Moscatelli, M.; Rezende, L.G.; Lacerda, L.D

2002-12-01

Mangrove sediments may prevent movement of metals to adjacent bodies of water. - The accumulation of Hg, Zn, and Cu was evaluated in mangrove sediments located between a large, 20-years-old landfill and waters of Guanabara Bay (southeast Brazil). The contamination history of the area provides substantial evidence that metal accumulation in the study site is influenced by past metal emissions from multiple sources (e.g. contaminated rivers and the landfill surrounding the site). At the southern part of the site, metal levels are up to 890 ng g{sup -1} Hg, 850 {mu}g g{sup -1} Zn, and 58 {mu}g g{sup -1} Cu. Enrichment factors and excess (background-deducted) concentration inventories show a high spatial variability of metal contamination and storage in the site, with differences often by a factor higher than two within a sampling station and higher than five between sampling stations. These contrasts are attributable to a coupling between spatial variability of anthropogenic metal input and metal behavior and retention within the sediments. Results indicate that during the last few decades mangrove sediments retained a substantial part of metal emissions to the site, probably reducing the metal transport to Guanabara Bay waters, and suggest the suitability of mangrove ecosystems as physical and biogeochemical barriers to metal contaminant transport.

Mercury, zinc, and copper accumulation in mangrove sediments surrounding a large landfill in southeast Brazil

International Nuclear Information System (INIS)

Machado, W.; Moscatelli, M.; Rezende, L.G.; Lacerda, L.D.

2002-01-01

Mangrove sediments may prevent movement of metals to adjacent bodies of water. - The accumulation of Hg, Zn, and Cu was evaluated in mangrove sediments located between a large, 20-years-old landfill and waters of Guanabara Bay (southeast Brazil). The contamination history of the area provides substantial evidence that metal accumulation in the study site is influenced by past metal emissions from multiple sources (e.g. contaminated rivers and the landfill surrounding the site). At the southern part of the site, metal levels are up to 890 ng g -1 Hg, 850 μg g -1 Zn, and 58 μg g -1 Cu. Enrichment factors and excess (background-deducted) concentration inventories show a high spatial variability of metal contamination and storage in the site, with differences often by a factor higher than two within a sampling station and higher than five between sampling stations. These contrasts are attributable to a coupling between spatial variability of anthropogenic metal input and metal behavior and retention within the sediments. Results indicate that during the last few decades mangrove sediments retained a substantial part of metal emissions to the site, probably reducing the metal transport to Guanabara Bay waters, and suggest the suitability of mangrove ecosystems as physical and biogeochemical barriers to metal contaminant transport

Incident Cardiovascular Disease Among Adults With Blood Pressure Hg.

Science.gov (United States)

Tajeu, Gabriel S; Booth, John N; Colantonio, Lisandro D; Gottesman, Rebecca F; Howard, George; Lackland, Daniel T; O'Brien, Emily C; Oparil, Suzanne; Ravenell, Joseph; Safford, Monika M; Seals, Samantha R; Shimbo, Daichi; Shea, Steven; Spruill, Tanya M; Tanner, Rikki M; Muntner, Paul

2017-08-29

Data from before the 2000s indicate that the majority of incident cardiovascular disease (CVD) events occur among US adults with systolic and diastolic blood pressure (SBP/DBP) ≥140/90 mm Hg. Over the past several decades, BP has declined and hypertension control has improved. We estimated the percentage of incident CVD events that occur at SBP/DBP Hg in a pooled analysis of 3 contemporary US cohorts: the REGARDS study (Reasons for Geographic and Racial Differences in Stroke), the MESA (Multi-Ethnic Study of Atherosclerosis), and the JHS (Jackson Heart Study) (n=31 856; REGARDS=21 208; MESA=6779; JHS=3869). Baseline study visits were conducted in 2003 to 2007 for REGARDS, 2000 to 2002 for MESA, and 2000 to 2004 for JHS. BP was measured by trained staff using standardized methods. Antihypertensive medication use was self-reported. The primary outcome was incident CVD, defined by the first occurrence of fatal or nonfatal stroke, nonfatal myocardial infarction, fatal coronary heart disease, or heart failure. Events were adjudicated in each study. Over a mean follow-up of 7.7 years, 2584 participants had incident CVD events. Overall, 63.0% (95% confidence interval [CI], 54.9-71.1) of events occurred in participants with SBP/DBP Hg; 58.4% (95% CI, 47.7-69.2) and 68.1% (95% CI, 60.1-76.0) among those taking and not taking antihypertensive medication, respectively. The majority of events occurred in participants with SBP/DBP Hg among those Hg, 76.6% (95% CI, 75.8-77.5) were eligible for statin treatment, but only 33.2% (95% CI, 32.1-34.3) were taking one, and 19.5% (95% CI, 18.5-20.5) met the SPRINT (Systolic Blood Pressure Intervention Trial) eligibility criteria and may benefit from a SBP target goal of 120 mm Hg. Although higher BP levels are associated with increased CVD risk, in the modern era, the majority of incident CVD events occur in US adults with SBP/DBP Hg. While absolute risk and cost-effectiveness should be considered, additional CVD risk

Stability and diffusion of Hg implanted YBa2Cu3O6+x

International Nuclear Information System (INIS)

Araujo, J.P.; Correia, J.G.; Wahl, U.; Marques, J.G.; Alves, E.; Amaral, V.S.; Lourenco, A.A.; Galindo, V.; Papen, T. von; Senateur, J.P.; Weiss, F.; Vantomme, A.; Langouche, G.; Melo, A.A.; Silva, M.F. da; Soares, J.C.; Sousa, J.B.

1999-01-01

The radioactive isotope 197m Hg was implanted at 60 keV with low fluences (10 13 ions/cm 2 ) into YBa 2 Cu 3 O 6+x (YBCO) superconducting thin films at ISOLDE/CERN. We report on the Hg dynamics and stability inside the YBCO lattice as a function of annealing temperature up to 890 K in a vacuum or O 2 atmosphere. The perturbed angular correlation (PAC) technique was used for probing the Hg behavior at the atomic scale, while by monitoring the sample's activity in situ the Hg outdiffusion was studied. We found that Hg ions occupy unique lattice sites and that Hg should be bound to two apical oxygens. Hg diffusion occurs only for annealing temperatures above 653 K, in vacuum. The Hg migration energy was estimated to be E M =1.58±0.15 eV

40 CFR 60.4120 - General Hg budget trading program permit requirements.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false General Hg budget trading program... and Compliance Times for Coal-Fired Electric Steam Generating Units Permits § 60.4120 General Hg budget trading program permit requirements. (a) For each Hg Budget source required to have a title V...

One-pot Sonochemical Synthesis of Hg-Ag Alloy Microspheres from Liquid Mercury.

Science.gov (United States)

Harika, Villa Krishna; Kumar, Vijay Bhooshan; Gedanken, Aharon

2018-01-01

Metallic mercury has always attracted much attention in various fields because of its unique characteristic of forming amalgams. Here, different phases of pure crystalline Hg-Ag amalgam microspheres are synthesized by ultrasonically reacting liquid mercury with an aqueous solution of silver nitrate. Sonicating different molar ratios of liquid metallic Hg with AgNO 3 results in the formation of pure crystalline phases of solid silver amalgams with uniform morphology. The resulting Hg-Ag amalgams from various compositions after sonication are physically characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Differential Scanning Calorimetry (DSC). The XRD of the amalgams obtained from the molar ratios of Hg:Ag (1:1.5) and Hg:Ag (1.5:1 and 2:1) match the Schachnerite and Moschellandbergite phases, respectively, whereas the Hg-Ag amalgam prepared from a 1:1Hg:Ag molar ratio results in a mixture of the Schachnerite and Moschellandbergite phases. The obtained amalgam microspheres are between 6 and 10µm in size. The detailed thermal and chemical behaviour of the Ag-Hg systems is also investigated. Copyright © 2017 Elsevier B.V. All rights reserved.

The trace metals accumulation in marine organisms of the southeastern Adriatic coast, Montenegro

Directory of Open Access Journals (Sweden)

Joksimovic Danijela

2012-01-01

Full Text Available The concentration and accumulation of trace metals (Co, Ni, As, Cd, Pb and Hg were measured in sea water, sediments and marine organisms in the coastline of the Montenegro. The obtained results of trace metals in seagrass and mussels were compared with those found in the water column and sediment. Sampling was performed in the fall of 2005 at five locations in the Montenegrin coastline, Sveta Stasija, Herceg Novi, Zanjice, Budva and Bar, which present different levels and sources of human impact. The heavy metals analyses in seawater, sediment, P. oceanica and M. galloprovincialis identified the harbor of Bar as the most Hg-contaminated site, Zanjice as the most As contaminated and Sveta Stasija as the most Pb-contaminated areas of the Montenegrin coastal area. This study showed that P. oceanica may have a greater bioaccumulation capacity than M. galloprovincialis for the considered metals, except for As and Hg, and both organisms may reflect contamination in the water column and in the sediment. For the first time, seagrass P. oceanica and M. galloprovincialis were employed as metal bioindicators for the southeastern Adriatic. The results of this study could serve as a baseline in the future for the assessment of anthropogenic effects in this marine ecosystem.

Distribution and air-sea exchange of mercury (Hg in the Yellow Sea

Directory of Open Access Journals (Sweden)

Z. J. Ci

2011-03-01

Full Text Available The Yellow Sea, surrounded by East China and the Korea Peninsula, is a potentially important receptor for anthropogenic mercury (Hg emissions from East Asia. However, there is little documentation about the distribution and cycle of Hg in this marine system. During the cruise covering the Yellow Sea in July 2010, gaseous elemental mercury (GEM or Hg(0 in the atmosphere, total Hg (THg, reactive Hg (RHg and dissolved gaseous mercury (DGM, largely Hg(0 in the waters were measured aboard the R/V Kexue III. The mean (±SD concentration of GEM over the entire cruise was 2.61 ± 0.50 ng m⁻³ (range: 1.68 to 4.34 ng m⁻³, which were generally higher than other open oceans. The spatial distribution of GEM generally reflected a clear gradient with high levels near the coast of East China and low levels in open waters, suggesting the significant atmospheric Hg outflow from East China. The mean concentration of THg in the surface waters was 1.69 ± 0.35 ng l⁻¹ and the RHg accounted for a considerable fraction of THg (RHg: 1.08 ± 0.28 ng l⁻¹, %RHg/THg = 63.9%. The mean concentration of DGM in the surface waters was 63.9 ± 13.7 pg l⁻¹ and always suggested the supersaturation of Hg(0 in the surface waters with respect to Hg(0 in the atmosphere (the degree of saturation: 7.8 ± 2.3 with a range of 3.6–14.0. The mean Hg(0 flux at the air-sea interface was estimated to be 18.3 ± 11.8 ng m⁻² h⁻¹ based on a two-layer exchange model. The high wind speed and DGM levels induced the extremely high Hg(0 emission rates. Measurements at three stations showed no clear vertical patterns of DGM, RHg and THg in the water column. Overall, the elevated Hg levels in the Yellow Sea compared with other open oceans suggested that the human activity has influenced the oceanic Hg cycle downwind of East Asia.

Stability studies of Hg implanted YBa$_{2}$Cu$_{3}$O$_{6+x}$

CERN Document Server

Araújo, J P; Wahl, U; Marques, J G; Alves, E; Amaral, V S; Lourenço, A A; Galindo, V; Von Papen, T; Senateur, J P; Weiss, F; Vantomme, A; Langouche, G; Melo, A A; Da Silva, M F A; Soares, J C; Sousa, J B

1999-01-01

High quality YBa$_{2}$Cu$_{3}$O$_{6+x}$ (YBCO) superconducting thin films were implanted with the radioactive $^{197m}$Hg (T$_{1/2}$ = 24 h) isotope to low fluences of 10$^{13}$ atoms/cm$^{2}$ and 60 keV energy. The lattice location and stability of the implanted Hg were studied combining the Perturbed Angular Correlation (PAC) and Emission Channeling (EC) techniques. We show that Hg can be introduced into the YBCO lattice by ion implantation into unique regular sites. The EC data show that Hg is located on a highly symmetric site on the YBCO lattice, while the PAC data suggests that Hg occupies the Cu(1) site. Annealing studies were performed under vacuum and O$_{2}$ atmosphere and show that Hg starts to diffuse only above 653 K.

History of HgTe-based photodetectors in Poland

Science.gov (United States)

Rogalski, A.

2010-09-01

In Poland, the HgCdTe studies began in 1960 at the Institute of Physics, Warsaw University. The material processing laboratory was created by Giriat and later by Dziuba, Gałązka, and others. Bridgman technique with sealed thick wall quartz ampoules was used to grow material suitable for research and experimental devices. Among the first papers published in 1961 and 1963 there were the Polish works devoted to preparation, doping, and electrical properties of HgCdTe. Infrared detector's research and development efforts in Poland were concentrated mostly on uncooled market niche. At the beginning, a modified isothermal vapour phase epitaxy has been used for research and commercial fabrication of photoconductive, photoelectromagnetic and other HgCdTe devices. Bulk growth and liquid phase epitaxy were also used. Recently, the fabrication of infrared devices relies on low temperature epitaxial technique, namely metalorganic vapour phase deposition. At present stage of development, the photoconductive and photoelectromagnetic (PEM) detectors are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, photodiodes offer high performance and very fast response. However, conventional photovoltaic uncooled detectors suffer from low quantum efficiency and very low junction resistance. The problems have been solved with advanced band gap engineered architecture, multiple cell heterojunction devices connected in series, and monolithic integration of the detectors with microoptics. In final part of the paper, the Polish achievements in technology and performance of HgMnTe and HgZnTe photodetectors are presented.

Reduced Limit on the Permanent Electric Dipole Moment of ^{199}Hg.

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