WorldWideScience

Sample records for total soil hg

  1. 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

  2. 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

  3. Overcoming phytoremediation limitations. A case study of Hg contaminated soil

    Science.gov (United States)

    Barbafieri, Meri

    2013-04-01

    an increase in Hg concentration of 248% in shoots and 185% in roots with respect to control plants. The BCS efficiency were evaluated analyzing the labile-Hg residue in the soil after the plant growing. Plants grown with CK and TS in one growing cycle significantly affected labile-Hg pools in soil characterized by sequential extraction, but did not significantly reduce the total metals in the soil. Moreover, if properly optimized, the use of a coupled phytohormone/thioligand system may be a viable strategy to strength Hg uptake by crop plants.

  4. 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

  5. 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...

  6. 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

  7. 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.

  8. Identification of Potential Sources of Mercury (Hg) in Farmland Soil Using a Decision Tree Method in China.

    Science.gov (United States)

    Zhong, Taiyang; Chen, Dongmei; Zhang, Xiuying

    2016-11-09

    Identification of the sources of soil mercury (Hg) on the provincial scale is helpful for enacting effective policies to prevent further contamination and take reclamation measurements. The natural and anthropogenic sources and their contributions of Hg in Chinese farmland soil were identified based on a decision tree method. The results showed that the concentrations of Hg in parent materials were most strongly associated with the general spatial distribution pattern of Hg concentration on a provincial scale. The decision tree analysis gained an 89.70% total accuracy in simulating the influence of human activities on the additions of Hg in farmland soil. Human activities-for example, the production of coke, application of fertilizers, discharge of wastewater, discharge of solid waste, and the production of non-ferrous metals-were the main external sources of a large amount of Hg in the farmland soil.

  9. Influence of ore processing activity on Hg, As and Sb contamination and fractionation in soils in a former mining site of Monte Amiata ore district (Italy).

    Science.gov (United States)

    Protano, Giuseppe; Nannoni, Francesco

    2018-05-01

    A geochemical study was carried out at the former Abbadia San Salvatore (ASS) mining site of the Monte Amiata ore district (Italy). Hg, As and Sb total contents and fractionation using a sequential extraction procedure were determined in soil and mining waste samples. Ore processing activities provided a different contribution to Hg contamination and concentration in soil fractions, influencing its behaviour as volatility and availability. Soils of roasting zone showed the highest Hg contamination levels mainly due to the deposition of Hg released as Hg 0 by furnaces during cinnabar roasting. High Hg contents were also measured in waste from the lower part of mining dump due to the presence of cinnabar. The fractionation pattern suggested that Hg was largely as volatile species in both uncontaminated and contaminated soils and mining waste, and concentrations of these Hg species increased as contamination increased. These findings were in agreement with the fact that the ASS mining site is characterized by high Hg concentrations in the air and the presence of Hg 0 liquid droplets in soil. Volatile Hg species were also prevalent in uncontaminated soils likely because the Monte Amiata region is an area characterized by anomalous fluxes of gaseous Hg from natural and anthropogenic inputs. At the ASS mining site soils were also contaminated by Sb, while As contents were comparable with its local background in soil. In all soil and waste samples Sb and As were preferentially in residual fraction. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. 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.

  11. Early Hg mobility in cultivated tropical soils one year after slash-and-burn of the primary forest, in the Brazilian Amazon.

    Science.gov (United States)

    Béliveau, Annie; Lucotte, Marc; Davidson, Robert; Lopes, Luis Otávio do Canto; Paquet, Serge

    2009-07-15

    In the Brazilian Amazon, forest conversion to agricultural lands (slash-and-burn cultivation) contributes to soil mercury (Hg) release and to aquatic ecosystem contamination. Recent studies have shown that soil Hg loss occurs rapidly after deforestation, suggesting that Hg mobility could be related to the massive cation input resulting from biomass burning. The objective of this research was to determine the effects of the first year of slash-and-burn agriculture on soil Hg levels at the regional scale of the Tapajós River, in the state of Pará, Brazilian Amazon. A total of 429 soil samples were collected in 26 farms of five riparian communities of the Tapajós basin. In September 2004, soil samples were collected from primary forest sites planned for slash-and-burn cultivation. In August 2005, one year after the initial burning, a second campaign was held and the exact same sites were re-sampled. Our results showed that total Hg levels in soils did not change significantly during the first year following slash-and-burn, suggesting no immediate release of soil Hg at that point in time. However, an early Hg mobility was detected near the surface (0-5 cm), reflected by a significant shift in Hg distribution in soil fractions. Indeed, a transfer of Hg from fine to coarser soil particles was observed, indicating that chemical bonds between Hg and fine particles could have been altered. A correspondence analysis (CA) showed that this process could be linked to a chemical competition caused by cation enrichment. The regional dimension of the study highlighted the prevailing importance of soil types in Hg dynamics, as shown by differentiated soil responses following deforestation according to soil texture. Confirming an early Hg mobility and indicating an eventual Hg release out of the soil, our results reinforce the call for the development of more sustainable agricultural practices in the Amazon.

  12. 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

  13. Regional Variability of Cd, Hg, Pb and C Concentrations in Different Horizons of Swedish Forest Soils

    International Nuclear Information System (INIS)

    Alriksson, A.

    2001-01-01

    Contents of cadmium (Cd), mercury (Hg), lead (Pb) and carbon(C) in the O, B and C horizons of podzolized forest soils in Sweden were surveyed. Concentrations and storage of Cd, Hg and Pb in the O and B horizons were high in southern Sweden and gradually decreased towards the north, though with considerable local variability. This pattern reflects the influence of anthropogenic emissions of these metals, as well as the effects of soil-forming processes. Parent till material, as represented by the C horizon concentration of the respective metal, accounted for little of the variation in metal concentration in the O horizon. For Cd and Pb, the correlations were not significant or slightly negative (R 2 = 0.12 and 0.09 respectively) depending on region, while for Hg the correlation was not significant or slightly positive (R 2 = 0.03 and 0.08). Furthermore, parent till material accounted for more of the variation in metal concentrations in the B horizons in the northern part of Sweden than in the middle and southernmost parts, where the concentration of total carbon had more influence. The correlation between the metal concentrations in the B and C horizon was strongest for Pb (R 2 = 0.63 and 0.36 in the two northernmost regions), lower for Cd (R 2 = 0.19 and 0.16) and not significant for Hg. For all soil horizons, total C concentration accounted for much of the variation in Hg concentration in particular (O-horizon R 2 = 0.15-0.69, B horizon R 2 = 0.36-0.50, C horizon R 2 = 0.23-0.50 and ns in one region). Ratios of metal concentrations between the B and C horizons were highest for Hg(maximum value of 30), indicating a relatively larger addition or retention of Hg compared to Cd and Pb (maximum value of 10)in the B horizon. This study indicate that factors other than parent material account for the large scale variation in O horizon concentrations of metals but patterns correspond well with those of atmospheric deposition of heavy metals and acidifying substances

  14. Critical Limits for Hg(II) in soils, derived from chronic toxicity data

    International Nuclear Information System (INIS)

    Tipping, E.; Lofts, S.; Hooper, H.; Frey, B.; Spurgeon, D.; Svendsen, C.

    2010-01-01

    Published chronic toxicity data for Hg(II) added to soils were assembled and evaluated to produce a data set comprising 52 chronic end-points, five each for plants and invertebrates and 42 for microbes. With end-points expressed in terms of added soil Hg(II) contents, Critical Limits were derived from the 5th percentiles of species sensitivity distributions, values of 0.13 μg (g soil) -1 and 3.3 μg (g soil organic matter) -1 being obtained. The latter value exceeds the currently recommended Critical Limit, used to determine Hg(II) Critical Loads in Europe, of 0.5 μg (g soil organic matter) -1 . We also applied the WHAM/Model VI chemical speciation model to estimate concentrations of Hg 2+ in soil solution, and derived an approximate Critical Limit Function (CLF) that includes pH; log [Hg 2+ ] crit = -2.15 pH -17.10. Because they take soil properties into account, the soil organic matter-based limit and the CLF provide the best assessment of toxic threat for different soils. For differing representative soils, each predicts a range of up to 100-fold in the dry weight-based content of mercury that corresponds to the Critical Limit. - Published laboratory toxicity data and chemical speciation modelling are used to derive Critical Limits expressed as either soil Hg(II) content or Hg 2+ concentration.

  15. 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.

  16. 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.

  17. 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.

  18. Prediction of the fate of Hg and other contaminants in soil around a former chlor-alkali plant using Fuzzy Hierarchical Cross-Clustering approach.

    Science.gov (United States)

    Frenţiu, Tiberiu; Ponta, Michaela; Sârbu, Costel

    2015-11-01

    An associative simultaneous fuzzy divisive hierarchical algorithm was used to predict the fate of Hg and other contaminants in soil around a former chlor-alkali plant. The algorithm was applied on several natural and anthropogenic characteristics of soil including water leachable, mobile, semi-mobile, non-mobile fractions and total Hg, Al, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Sr, Zn, water leachable fraction of Cl(-), NO3(-) and SO4(2)(-), pH and total organic carbon. The cross-classification algorithm provided a divisive fuzzy partition of the soil samples and associated characteristics. Soils outside the perimeter of the former chlor-alkali plant were clustered based on the natural characteristics and total Hg. In contaminated zones Hg speciation becomes relevant and the assessment of species distribution is necessary. The descending order of concentration of Hg species in the test site was semi-mobile>mobile>non-mobile>water-leachable. Physico-chemical features responsible for similarities or differences between uncontaminated soil samples or contaminated with Hg, Cu, Zn, Ba and NO3(-) were also highlighted. Other characteristics of the contaminated soil were found to be Ca, sulfate, Na and chloride, some of which with influence on Hg fate. The presence of Ca and sulfate in soil induced a higher water leachability of Hg, while Cu had an opposite effect by forming amalgam. The used algorithm provided an in-deep understanding of processes involving Hg species and allowed to make prediction of the fate of Hg and contaminants linked to chlor-alkali-industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Critical Limits for Hg(II) in soils, derived from chronic toxicity data

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E., E-mail: et@ceh.ac.u [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Lofts, S. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Hooper, H. [Centre for Ecology and Hydrology, Wallingford, OX10 8BB (United Kingdom); Frey, B. [Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Spurgeon, D.; Svendsen, C. [Centre for Ecology and Hydrology, Wallingford, OX10 8BB (United Kingdom)

    2010-07-15

    Published chronic toxicity data for Hg(II) added to soils were assembled and evaluated to produce a data set comprising 52 chronic end-points, five each for plants and invertebrates and 42 for microbes. With end-points expressed in terms of added soil Hg(II) contents, Critical Limits were derived from the 5th percentiles of species sensitivity distributions, values of 0.13 {mu}g (g soil){sup -1} and 3.3 {mu}g (g soil organic matter){sup -1} being obtained. The latter value exceeds the currently recommended Critical Limit, used to determine Hg(II) Critical Loads in Europe, of 0.5 {mu}g (g soil organic matter){sup -1}. We also applied the WHAM/Model VI chemical speciation model to estimate concentrations of Hg{sup 2+} in soil solution, and derived an approximate Critical Limit Function (CLF) that includes pH; log [Hg{sup 2+}]{sub crit} = -2.15 pH -17.10. Because they take soil properties into account, the soil organic matter-based limit and the CLF provide the best assessment of toxic threat for different soils. For differing representative soils, each predicts a range of up to 100-fold in the dry weight-based content of mercury that corresponds to the Critical Limit. - Published laboratory toxicity data and chemical speciation modelling are used to derive Critical Limits expressed as either soil Hg(II) content or Hg{sup 2+} concentration.

  20. Total mercury, methyl mercury, and carbon in fresh and burned plants and soil in Northwestern Ontario

    International Nuclear Information System (INIS)

    Mailman, M.; Bodaly, R.A.

    2005-01-01

    Terrestrial plants and soil contain substantial amounts of organic carbon (C) and mercury. Flooding terrestrial areas stimulates microbial methyl mercury (MeHg) production and fish obtain elevated MeHg concentrations. Our purpose was to determine the loss of C, total mercury (THg), and MeHg from boreal plants and soil after burning to assess the potential of burning before flooding to lower MeHg. Fresh plants contained 4 to 52 ng g -1 dry weight (dw) of THg and 0.1 to 1.3 ng g -1 dw of MeHg. Upland soils contained 162±132 ng g -1 dw of THg and 0.6±0.6 ng g -1 dw of MeHg. Complete burning caused plants to lose 96, 98, 97, and 94% of the mass, C, THg, and MeHg, respectively. Upland soil lost 27, 95, 79, and 82% of the mass, C, THg, and MeHg, respectively. Our results demonstrated that a substantial loss of C, THg, and MeHg was caused by burning. - Burning terrestrial vegetation and soil causes substantial losses of organic carbon, total mercury, and methyl mercury

  1. Total mercury, methyl mercury, and carbon in fresh and burned plants and soil in Northwestern Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Mailman, M. [Department of Zoology, University of Manitoba, Winnipeg, Man. R3T 2N2 (Canada); Freshwater Institute, 501 University Crescent, Winnipeg, Man. R3T 2N6 (Canada)]. E-mail: mailmanma@dfo-mpo.gc.ca; Bodaly, R.A. [Department of Zoology, University of Manitoba, Winnipeg, Man. R3T 2N2 (Canada); Freshwater Institute, 501 University Crescent, Winnipeg, Man. R3T 2N6 (Canada)

    2005-11-15

    Terrestrial plants and soil contain substantial amounts of organic carbon (C) and mercury. Flooding terrestrial areas stimulates microbial methyl mercury (MeHg) production and fish obtain elevated MeHg concentrations. Our purpose was to determine the loss of C, total mercury (THg), and MeHg from boreal plants and soil after burning to assess the potential of burning before flooding to lower MeHg. Fresh plants contained 4 to 52 ng g{sup -1} dry weight (dw) of THg and 0.1 to 1.3 ng g{sup -1} dw of MeHg. Upland soils contained 162{+-}132 ng g{sup -1} dw of THg and 0.6{+-}0.6 ng g{sup -1} dw of MeHg. Complete burning caused plants to lose 96, 98, 97, and 94% of the mass, C, THg, and MeHg, respectively. Upland soil lost 27, 95, 79, and 82% of the mass, C, THg, and MeHg, respectively. Our results demonstrated that a substantial loss of C, THg, and MeHg was caused by burning. - Burning terrestrial vegetation and soil causes substantial losses of organic carbon, total mercury, and methyl mercury.

  2. Comparing different commercial zero valent iron nanoparticles to immobilize As and Hg in brownfield soil.

    Science.gov (United States)

    Gil-Díaz, M; Alonso, J; Rodríguez-Valdés, E; Gallego, J R; Lobo, M C

    2017-04-15

    Nanoscale zero valent iron (nZVI) particles obtained by different methods differ in their structure, which lead to different reactivity, and therefore a likely difference in the remediation efficiency. The present study compares the effectiveness of three commercial ZVI nanoparticles to immobilize As and Hg in two soils (A and B) collected from a brownfield highly contaminated by mining and metallurgy activities. Scarce data are available on the effectiveness of nZVI for Hg immobilization in soil. Two commercial nZVI slurries from Toda (RNIP and RNIP-D) and one from Nano Iron (25S) were used at different doses (1, 5 and 10%). The metal(loid) availability and mobility was evaluated with the TCLP test and Tessier extraction procedure. The influence of nZVI application on As and Hg speciation was also evaluated as well as its impact on soil pH, electrical conductivity and soil phytotoxicity to vetch germination. The three commercial nZVI particles significantly reduced As and Hg availability in the two soils studied, which led to a decrease in soil phytotoxicity. At the dose of 5% of nZVI a decrease of exchangeable-As higher than 70% was observed for both soils, whereas in the case of Hg, a higher dose of nZVI (10%) was necessary to achieve reductions of exchangeable-Hg between 63 and 90% depending on the type of nZVI and soil. No impact on soil pH and electrical conductivity was observed. The effectiveness of metal(loid) immobilization depended on type of nZVI, soil properties and metal(loid) characteristics. Nanoparticles from Nano Iron showed better results for As immobilization whereas RNIP nanoparticles were more effective for Hg. Overall, 25S at the dose of 5% resulted more effective than RNIP nanoparticles for the reduction of exchangeable-As (in the range of 6-14%), whereas RNIP and RNIP-D were 10 and 13% more effective, respectively, for the reduction of exchangeable-Hg at the dose of 10% in soil B. Thus, nZVI can be used for the remediation of highly As and

  3. Recovery of total Hg from geological matrices: a methodological intercomparison study (W6)

    International Nuclear Information System (INIS)

    Bloom, N.S.; Vondergeest, E.J.; Preus, E.M.; Horvat, M.; Prosenc, N.; Kingston, S.; Apte, S.; Pobbs, C.

    2002-01-01

    Full text: Aqua regia is commonly used for the extraction of Hg from soils prior to cold vapor spectrometry, but mass balance studies suggested it is not sufficiently robust to recover all Hg from more recalcitrant materials such as crystalline ores. As a result, an intercomparison exercise was undertaken between the following methods: (a) aqua regia digestion (EPA 7471) followed by SnCl 2 reduction, gold trapping and CVAFS detection, (b) Teflon bomb digestion at 110 o C with a 10:5:2 HNO 3 + HF + HCl mixture followed by SnCl 2 reduction, gold trapping and CVAFS, (c) 800 o C pyrolysis with gold trapping and CVAAS detection (EPA 7473), and (d) NAA followed by radiochemical separations using oxidative combustion and gold trapping. All methods gave quantitative recoveries from soil and sediment CRMs, but only the HF/HCI/HNO 3 digestion gave quantitative recoveries in all media. Pyrolysis resulted in approximately 88 ± 10 % recovery, while aqua regia digestion resulted in only about 61 ± 24 % recovery in bauxite ores and residues. RNAA generally gave the best agreement with the HF based digestion, although in a significant number of samples, particularly bauxite ores, recoveries were as low as 50 %. Based on these findings, we recommend that bomb digestions which include the use HF be applied to the analysis of Hg in geological solids, unless the matrix is documented to be fully extractable by a less rigorous procedure. We suggest a reference value for Hg in bauxite reference material (NIST-600) of 79.0 ± 2.0 ng/g, based on the pooled results of three laboratories. (author)

  4. Soil surface Hg emission flux in coalfield in Wuda, Inner Mongolia, China.

    Science.gov (United States)

    Li, Chunhui; Liang, Handong; Liang, Ming; Chen, Yang; Zhou, Yi

    2018-03-30

    Hg emission flux from various land covers, such as forests, wetlands, and urban areas, have been investigated. China has the largest area of coalfield in the world, but data of Hg flux of coalfields, especially, those with coal fires, are seriously limited. In this study, Hg fluxes of a coalfield were measured using the dynamic flux chamber (DFC) method, coupled with a Lumex multifunctional Hg analyzer RA-915+ (Lumex Ltd., Russia). The results show that the Hg flux in Wuda coalfield ranged from 4 to 318 ng m -2  h -1 , and the average value for different areas varied, e.g., coal-fire area 99 and 177 ng m -2  h -1 ; no coal-fire area 19 and 32 ng m -2  h -1 ; and backfilling area 53 ng m -2  h -1 . Hg continued to be emitted from an underground coal seam, even if there were no phenomena, such as vents, cracks, and smog, of coal fire on the soil surface. This phenomenon occurred in all area types, i.e., coal-fire area, no coal-fire area, and backfilling area, which is universal in Wuda coalfield. Considering that many coalfields in northern China are similar to Wuda coalfield, they may be large sources of atmospheric Hg. The correlations of Hg emission flux with influence factors, such as sunlight intensity, soil surface temperature, and atmospheric Hg content, were also investigated for Wuda coalfield. Graphical abstract ᅟ.

  5. Total mercury and methylmercury concentrations over a gradient of contamination in earthworms living in rice paddy soil.

    Science.gov (United States)

    Abeysinghe, Kasun S; Yang, Xiao-Dong; Goodale, Eben; Anderson, Christopher W N; Bishop, Kevin; Cao, Axiang; Feng, Xinbin; Liu, Shengjie; Mammides, Christos; Meng, Bo; Quan, Rui-Chang; Sun, Jing; Qiu, Guangle

    2017-05-01

    Mercury (Hg) deposited from emissions or from local contamination, can have serious health effects on humans and wildlife. Traditionally, Hg has been seen as a threat to aquatic wildlife, because of its conversion in suboxic conditions into bioavailable methylmercury (MeHg), but it can also threaten contaminated terrestrial ecosystems. In Asia, rice paddies in particular may be sensitive ecosystems. Earthworms are soil-dwelling organisms that have been used as indicators of Hg bioavailability; however, the MeHg concentrations they accumulate in rice paddy environments are not well known. Earthworm and soil samples were collected from rice paddies at progressive distances from abandoned mercury mines in Guizhou, China, and at control sites without a history of Hg mining. Total Hg (THg) and MeHg concentrations declined in soil and earthworms as distance increased from the mines, but the percentage of THg that was MeHg, and the bioaccumulation factors in earthworms, increased over this gradient. This escalation in methylation and the incursion of MeHg into earthworms may be influenced by more acidic soil conditions and higher organic content further from the mines. In areas where the source of Hg is deposition, especially in water-logged and acidic rice paddy soil, earthworms may biomagnify MeHg more than was previously reported. It is emphasized that rice paddy environments affected by acidifying deposition may be widely dispersed throughout Asia. Environ Toxicol Chem 2017;36:1202-1210. © 2016 SETAC. © 2016 SETAC.

  6. Using a plant hormone and a thioligand to improve phytoremediation of Hg-contaminated soil from a petrochemical plant.

    Science.gov (United States)

    Cassina, L; Tassi, E; Pedron, F; Petruzzelli, G; Ambrosini, P; Barbafieri, M

    2012-09-15

    Mercury-contaminated soils from a petrochemical plant in southern Italy were investigated to assess the phytoextraction efficiency of crop plants treated with the phytohormone, cytokinine (CK foliar treatment), and with the thioligand, ammonium thiosulfate (TS, soil application). Plant biomass, evapotranspiration, Hg uptake and distribution in plant tissues following treatment were compared. Results indicate the effectiveness of CK in increasing plant biomass and the evapotranspiration rate while TS treatment promoted soil Hg solubility and availability. The simultaneous addition of CK and TS treatments increased Hg uptake and translocation in both tested plants with up to 248 and 232% in Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) respectively. B. juncea was more effective in Hg uptake, whereas H. annuus gave better response regarding plant biomass production. The effectiveness of the treatments was confirmed by the calculation of Hg phytoextraction and evaluation of labile-Hg residue in the soil after plant growth. In one growing cycle the plants subject to simultaneous CK and TS treatment significantly reduced labile-Hg pools that were characterized by the soil sequential extraction, but did not significantly affect the pseudototal metal content in the soil. Results support the use of plant growth regulators in the assisted phytoextraction process for Hg-contaminated soils. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. 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

  8. 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.

  9. Spatial Distribution of Mercury (Hg Concentration in Agricultural Soil and Its Risk Assessment on Food Safety in China

    Directory of Open Access Journals (Sweden)

    Shanqian Wang

    2016-08-01

    Full Text Available Soil mercury (Hg pollution in some areas of China is a serious problem and has aroused a lot of attention on a local scale. However, there are few studies on Hg pollution on a national scale. This study collected 444 published papers during 2005–2015 on Hg concentrations in agricultural soil throughout China, under seven land uses, namely: dry land, paddy field, vegetable field, tea garden, orchard, traditional Chinese medicine field and tobacco field, to assess the spatial distribution of Hg concentration and evaluate its influence on food safety. The averaged Hg concentration (0.108 mg/kg was higher than its background (0.065 mg/kg, but much lower than the guidelines (GB15618-1995 II for crop production. The spatial distribution of Hg throughout China showed great variability, with some hotspots due to Hg related mining and smelting activities. According to the Environment Quality Standard for soil in China (GB15618-1995 II, 4.2% of agricultural soil should be abandoned due to Hg pollution, and 2.0% faced a high risk of Hg pollution.

  10. Senegalese artisanal gold mining leads to elevated total mercury and methylmercury concentrations in soils, sediments, and rivers

    Directory of Open Access Journals (Sweden)

    Jacqueline R. Gerson

    2018-01-01

    Full Text Available The largest source of global mercury (Hg anthropogenic inputs to the environment is derived from artisanal and small-scale gold mining (ASGM activities in developing countries. While our understanding of global Hg emissions from ASGM is growing, there is limited empirical documentation about the levels of total mercury (THg and methylmercury (MeHg contamination near ASGM sites. We measured THg and MeHg concentrations in soil (n = 119, sediment (n = 22, and water (n = 25 from four active ASGM villages and one non-ASGM reference village in Senegal, West Africa. Nearly all samples had THg and MeHg concentrations that exceeded the reference village concentrations and USEPA regulatory standards. The highest median THg concentrations were found in huts where mercury-gold amalgams were burned (7.5 μg/g, while the highest median MeHg concentrations and percent Hg as MeHg were found in river sediments (4.2 ng/g, 0.41%. Median river water concentrations of THg and MeHg were also elevated compared to values at the reference site (22 ng THg/L, 0.037 ng MeHg/L in ASGM sites. This study provides direct evidence that Hg from ASGM is entering both the terrestrial and aquatic ecosystems where it is converted in soils, sediment, and water to the neurotoxic and bioavailable form of MeHg.

  11. Accumulation of methylmercury in rice and flooded soil in experiments with an enriched isotopic Hg(II) tracer

    Science.gov (United States)

    Strickman, R. J.; Mitchell, C. P. J.

    2015-12-01

    Methylmercury (MeHg) is a neurotoxin produced in anoxic aquatic sediments. Numerous factors, including the presence of aquatic plants, alter the biogeochemistry of sediments, affecting the rate at which microorganisms transform bioavailable inorganic Hg (IHg) to MeHg. Methylmercury produced in flooded paddy soils and its transfer into rice has become an important dietary consideration. An improved understanding of how MeHg reaches the grain and the extent to which rice alters MeHg production in rhizosphere sediments could help to inform rice cultivation practices. We conducted a controlled greenhouse experiment with thirty rice plants grown in individual, flooded pots amended with enriched 200Hg. Unvegetated controls were maintained under identical conditions. At three plant growth stages (vegetative growth, flowering, and grain maturity), ten plants were sacrificed and samples collected from soil, roots, straw, panicle, and grain of vegetated and unvegetated pots, and assessed for MeHg and THg concentrations. We observed consistent ratios between ambient and tracer MeHg between soils (0.36 ±0.04 — 0.44 ± 0.09) and plant compartments (0.23 ± 0.07 -0.34 ± 0.05) indicating that plant MeHg contamination originates in the soil rather than in planta methylation. The majority of this MeHg was absorbed between the tillering (4.48 ± 2.38 ng/plant) and flowering (8.43 ± 5.12 ng/pl) phases, with a subsequent decline at maturity (2.87 ± 1.23 ng/pl) only partly explained by translocation to the developing grain, indicating that MeHg was demethylated in planta. In contrast, IHg was absorbed from both soil and air, as evidenced by the higher ambient IHg concentrations compared to tracer (3.76 ± 1.19 vs. 0.27 ± 0.40 ng/g). Surprisingly, MeHg accumulation was significantly (p= 0.042-- 0.003) lower in vegetated vs. unvegetated sediments at flowering (1.41 ± 0.26 vs. 1.57 ± 0.23) and maturity (1.27 ± 0.22 vs. 1.71 ± 0.25), suggesting that plant exudates bound Hg

  12. Comparison of total Hg results in sediment samples from Rio Grande reservoir determine by NAA and CV AAS

    International Nuclear Information System (INIS)

    Franklin, Robson L.

    2011-01-01

    The Rio Grande reservoir is located in the Metropolitan area of Sao Paulo and it is used for recreation purposes and as source water for drinking water production. During the last decades has been detected mercury contamination in the sediments of this reservoir, mainly in the eastern part, near the main affluent of the reservoir, in the Rio Grande da Serra and Ribeirao Pires counties. In the present study bottom sediment samples were collected in four different sites into four sampling campaigns during the period of September 2008 to January 2010. The samples were dried at room temperature, ground and passed through a 2 mm sieve. Total Hg determination in the sediment samples was carried out by two different analytical techniques: neutron activation analysis (NAA) and cold vapor atomic absorption spectrometry (CV AAS). The methodology validation, in terms of precision and accuracy, was performed by reference materials, and presented a recovery of 83 to 108%. The total Hg results obtained by both analytical techniques ranged from 3 to 71 mg kg-1 and were considered similar by statistical analysis, even though NAA technique furnishes the total concentration while CV AAS using the 3015 digestion procedure characterizes only the bioavailable Hg. These results confirm that both analytical techniques were suitable to detect the Hg concentration levels in the Rio Grande sediments studied. The Hg levels in the sediment of the Rio Grande reservoir confirm the anthropogenic origin for this element in this ecosystem. (author)

  13. 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.

  14. Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater, Akaki, Ethiopia

    Science.gov (United States)

    Fitamo, Daniel; Itana, Fisseha; Olsson, Mats

    2007-02-01

    The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0-20 and 30-50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0-20 cm; and Cr, Ni, Cu, Cd, and Zn at 30-50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction

  15. The dynamics of mercury near Idrija mercury mine, Slovenia: Horizontal and vertical distributions of total, methyl, and ethyl mercury concentrations in soils.

    Science.gov (United States)

    Tomiyasu, Takashi; Kodamatani, Hitoshi; Imura, Ryusuke; Matsuyama, Akito; Miyamoto, Junko; Akagi, Hirokatsu; Kocman, David; Kotnik, Jože; Fajon, Vesna; Horvat, Milena

    2017-10-01

    The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg -1 . The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 μg kg -1 and n.d. to 17.4 μg kg -1 , respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Correlation between Soil Organic Matter, Total Organic Matter and ...

    African Journals Online (AJOL)

    A total of four sites distributed in different soils of Kelantan State, Malaysia was identified for the study. Soils were collected by depth interval of 0-10cm, 10-20cm and 20-30cm. The correlation of soil organic matter (SOM) content, total organic carbon (TOC) content, water content and soils texture for industrial area at ...

  17. An Integrated H-G Scheme Identifying Areas for Soil Remediation and Primary Heavy Metal Contributors: A Risk Perspective

    OpenAIRE

    Bin Zou; Xiaolu Jiang; Xiaoli Duan; Xiuge Zhao; Jing Zhang; Jingwen Tang; Guoqing Sun

    2017-01-01

    Traditional sampling for soil pollution evaluation is cost intensive and has limited representativeness. Therefore, developing methods that can accurately and rapidly identify at-risk areas and the contributing pollutants is imperative for soil remediation. In this study, we propose an innovative integrated H-G scheme combining human health risk assessment and geographical detector methods that was based on geographical information system technology and validated its feasibility in a renewabl...

  18. An Integrated H-G Scheme Identifying Areas for Soil Remediation and Primary Heavy Metal Contributors: A Risk Perspective.

    Science.gov (United States)

    Zou, Bin; Jiang, Xiaolu; Duan, Xiaoli; Zhao, Xiuge; Zhang, Jing; Tang, Jingwen; Sun, Guoqing

    2017-03-23

    Traditional sampling for soil pollution evaluation is cost intensive and has limited representativeness. Therefore, developing methods that can accurately and rapidly identify at-risk areas and the contributing pollutants is imperative for soil remediation. In this study, we propose an innovative integrated H-G scheme combining human health risk assessment and geographical detector methods that was based on geographical information system technology and validated its feasibility in a renewable resource industrial park in mainland China. With a discrete site investigation of cadmium (Cd), arsenic (As), copper (Cu), mercury (Hg) and zinc (Zn) concentrations, the continuous surfaces of carcinogenic risk and non-carcinogenic risk caused by these heavy metals were estimated and mapped. Source apportionment analysis using geographical detector methods further revealed that these risks were primarily attributed to As, according to the power of the determinant and its associated synergic actions with other heavy metals. Concentrations of critical As and Cd, and the associated exposed CRs are closed to the safe thresholds after remediating the risk areas identified by the integrated H-G scheme. Therefore, the integrated H-G scheme provides an effective approach to support decision-making for regional contaminated soil remediation at fine spatial resolution with limited sampling data over a large geographical extent.

  19. Determination of total mercury in aluminium industrial zones and soil contaminated with red mud.

    Science.gov (United States)

    Rasulov, Oqil; Zacharová, Andrea; Schwarz, Marián

    2017-08-01

    This study investigated total mercury contents in areas impacted by aluminium plants in Tajikistan and Slovakia and in one area flooded with red mud in Hungary. We present the first determination of total mercury contents in the near-top soil (0-10 and 10-20 cm) in Tajikistan and the first comparative investigation of Tajikistan-Slovakia-Hungary. The Tajik Aluminium Company (TALCO) is one of the leading producers of primary aluminium in Central Asia. In the past 30 years, the plant has been producing large volumes of industrial waste, resulting in negative impacts on soil, groundwater and air quality of the surrounding region. Mercury concentrations were significant in Slovakia and Hungary, 6 years after the flooding. In studied areas in Slovakia and Hungary, concentrations of total mercury exceeded the threshold limit value (TLV = 0.5 mg Hg kg -1 ). However, in Tajikistan, values were below the TLV (0.006-0.074 mg kg -1 ) and did not significantly vary between depths. Total Hg in Slovakia ranged from 0.057 to 0.668 mg kg -1 and in Hungary from 0.029 to 1.275 mg kg -1 . However, in the plots near to the red mud reservoir and the flooded area, Hg concentrations were higher in the upper layers than in the lower ones.

  20. Estimating Soil Bulk Density and Total Nitrogen from Catchment ...

    African Journals Online (AJOL)

    Even though data on soil bulk density (BD) and total nitrogen (TN) are essential for planning modern farming techniques, their data availability is limited for many applications in the developing word. This study is designed to estimate BD and TN from soil properties, land-use systems, soil types and landforms in the ...

  1. The average concentrations of As, Cd, Cr, Hg, Ni and Pb in residential soil and drinking water obtained from springs and wells in Rosia Montana area.

    Data.gov (United States)

    U.S. Environmental Protection Agency — The average concentrations of As, Cd, Cr, Hg, Ni and Pb in n=84 residential soil samples, in Rosia Montana area, analyzed by X-ray fluorescence spectrometry are...

  2. Divergent surface and total soil moisture projections under global warming

    Science.gov (United States)

    Berg, Alexis; Sheffield, Justin; Milly, Paul C.D.

    2017-01-01

    Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, total, and layer-by-layer soil moisture. We identify a robust vertical gradient of projected mean soil moisture changes, with more negative changes near the surface. Some regions of the northern middle to high latitudes exhibit negative annual surface changes but positive total changes. We interpret this behavior in the context of seasonal changes in the surface water budget. This vertical pattern implies that the extensive drying predicted by off-line drought metrics, while consistent with the projected decline in surface soil moisture, will tend to overestimate (negatively) changes in total soil water availability.

  3. Impact of Land Use on the Mobility of Hg Species in Different Compartments of a Tropical Watershed in Brazil.

    Science.gov (United States)

    de Lima, Clara Ayume Ito; de Almeida, Marcelo Gomes; Pestana, Inacio Abreu; Bastos, Wanderley R; do Nascimento Recktenvald, Maria Cristina Nery; de Souza, Cristina Maria Magalhães; Pedrosa, Paulo

    2017-11-01

    This study evaluated the levels of total Hg and CH 3 Hg + from a comprehensive perspective, considering the retention, leaching, and deposition of these contaminants in the main compartments (soil, plant litter, and sediment) of three landscapes (Atlantic Forest, pasture, and agricultural area) in a watershed in northern Rio de Janeiro State, Brazil. Variables analyzed were total Hg, CH 3 Hg + , organic carbon, total nitrogen, grain size, and surface area. In soil samples, total Hg levels were the highest in agricultural soil followed by forest soil and pasture (97.3, 87.6, and 77.1 ng g -1 , respectively), and CH 3 Hg + was lower than 1.7%. Total Hg levels in leaf litter varied between 22.6 and 34.2 ng g -1 , and CH 3 Hg + was 4.37%. In sediment, Hg (60-180 ng g -1 ) and CH 3 Hg + (Hg species, and the effect of each variable varied with the landscape, showing that plant cover should not be ignored in investigations related to Hg species retention in a watershed. The landscapes surveyed in the present study clearly influence the quantitative and qualitative distribution of Hg species. On the other hand, anthropic processes associated with changes in soil use did not have any critical effects on the absolute levels of total Hg and CH 3 Hg + , meaning that the landscapes evaluated seem to represent the background concentration of these chemical species for the evaluated watershed.

  4. Automated method for the determination of total arsenic and selenium in natural and drinking water by HG-AAS.

    Science.gov (United States)

    Pistón, Mariela; Silva, Javier; Pérez-Zambra, Ramiro; Dol, Isabel; Knochen, Moisés

    2012-04-01

    A multicommutated flow system was designed and evaluated for the determination of total arsenic and selenium by Hydride Generation Atomic Absorption Spectrometry (HG-AAS). It was applied to the determination of arsenic and selenium in samples of natural and drinking water. Detection limits were 0.46 and 0.08 μg l(-1) for arsenic and selenium, respectively; sampling frequency was 120 samples h(-1) for arsenic and 160 samples h(-1) for selenium. Linear ranges found were 1.54-10 μg l(-1) (R = 0.999) for arsenic and 0.27-27 μg l(-1) (R = 0.999) for selenium. Accuracy was evaluated by spiking various water samples and using a reference material. Recoveries were in the range 95-116%. Analytical precision (s ( r ) (%), n = 10) was 6% for both elements. Compared with the Standard Methods, APHA, 3114B manual method, the system consumes at least 10 times less sample per determination, and the quantities of acid and reducing agent used are significantly lower with a reduction in the generation of pollutants and waste. As an additional advantage, the system is very fast, efficient and environmentally friendly for monitoring total arsenic and selenium levels in waters.

  5. [Determination of total mass and morphology analysis of heavy metal in soil with potassium biphthalate-sodium hydroxide by ICP-AES].

    Science.gov (United States)

    Qu, Jiao; Yuan, Xing; Cong, Qiao; Wang, Shuang

    2008-11-01

    Blank soil was used as quality controlling samples, soil sample dealt by potassium biphthalate-sodium hydroxide buffer solution was used as check sample, mixed acid HNO3-HF-HClO4 was chosen to nitrify soil samples, and plasma emission spectrometer (ICP-AES) was used as detecting method. The authors determined the total metal mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the extracted and dealt soil samples, and determined the mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the three chemical morphologies, including acid extractable morphology, oxide associated morphology, and organics associated modality. The experimental results indicated that the different pH of potassium biphthalate-sodium hydroxide buffer solution had obvious influence on the total mass of heavy metal and morphology transformation. Except for metal element Pb and Zn, the addition of different pH potassium dihydrogen phosphate-sodium hydroxide buffer solution could accelerate the soil samples nitrification and the total mass determination of heavy metal in the soil samples. The potassium biphthalate-sodium hydroxide buffer solution could facilitate the acid extractable morphology of Cr, Cu, Hg and Pb, oxidation associated morphology of As, Hg, Pb and Zn and the organic associated morphology transforming of As and Hg. At pH 5.8, the maximum acid extractable morphology contents of Cu and Hg were 2.180 and 0.632 mg x kg(-1), respectively; at pH 6.2, the maximal oxidation associated morphology content of Pb could achieve 27.792 mg x kg(-1); at pH 6.0, the maximum organic associated morphology content of heavy metal Hg was 4.715 mg x kg(-1).

  6. Predicting Soluble Nickel in Soils Using Soil Properties and Total Nickel.

    Science.gov (United States)

    Zhang, Xiaoqing; Li, Jumei; Wei, Dongpu; Li, Bo; Ma, Yibing

    2015-01-01

    Soil soluble nickel (Ni) concentration is very important for determining soil Ni toxicity. In the present study, the relationships between soil properties, total and soluble Ni concentrations in soils were developed in a wide range of soils with different properties and climate characteristics. The multiple regressions showed that soil pH and total soil Ni concentrations were the most significant parameters in predicting soluble Ni concentrations with the adjusted determination coefficients (Radj2) values of 0.75 and 0.68 for soils spiked with soluble Ni salt and the spiked soils leached with artificial rainwater to mimic field conditions, respectively. However, when the soils were divided into three categories (pH 8), they obtained better predictions with Radj2 values of 0.78-0.90 and 0.79-0.94 for leached and unleached soils, respectively. Meanwhile, the other soil properties, such as amorphous Fe and Al oxides and clay, were also found to be important for determining soluble Ni concentrations, indicating that they were also presented as active adsorbent surfaces. Additionally, the whole soil speciation including bulk soil properties and total soils Ni concentrations were analyzed by mechanistic speciation models WHAM VI and Visual MINTEQ3.0. It was found that WHAM VI provided the best predictions for the soils with pH 8. The Visual MINTEQ3.0 could provide better estimation for pH 8. These results indicated the possibility and applicability of these models to predict soil soluble Ni concentration by soil properties.

  7. 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.

  8. 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

  9. Effect of fire on Hg pools in soils of forested ecosystem

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Hojdová, Maria; Rohovec, Jan; Penížek, V.; Vařilová, Z.

    2008-01-01

    Roč. 34, 4/6 (2008), s. 1340433-1340433 ISSN 0161-6951. [International Geological Congress /33./. 06.08.2008-14.08.2008, Oslo ] R&D Projects: GA ČR GP526/07/P170 Institutional research plan: CEZ:AV0Z30130516 Keywords : mercury * pools * forest soil * fire Subject RIV: DD - Geochemistry

  10. Mercúrio total em solos de manguezais da Baixada Santista e Ilha do Cardoso, estado de São Paulo Total mercury in mangrove soils of the Baixada Santista and Cardoso Island, São Paulo state

    Directory of Open Access Journals (Sweden)

    Mara Lucia Jacinto Oliveira

    2007-06-01

    Full Text Available Total Hg content in soils of Baixada Santista, affected by different sources of pollution, and Cardoso Island, which is almost free of anthropogenic activities, were determined by CVAAS. To explain the fate of Hg in the ecosystem, pH, Eh, AVS, Stotal and Total Organic Carbon were also obtained throughout the soil profiles. With the exception of two sampling sites the average content of Hg in samples obtained for Baixada Santista was 0.34 ± 0.20 mg kg-1, which was close to the average data at Cardoso Island (0.30 ± 0.21 mg kg-1. Both of them were below the limit established by CETESB - 0.50 mg kg-1.

  11. Diffuse Reflectance Spectroscopy for Total Carbon Analysis of Hawaiian Soils

    Science.gov (United States)

    McDowell, M. L.; Bruland, G. L.; Deenik, J. L.; Grunwald, S.; Uchida, R.

    2010-12-01

    Accurate assessment of total carbon (Ct) content is important for fertility and nutrient management of soils, as well as for carbon sequestration studies. The non-destructive analysis of soils by diffuse reflectance spectroscopy (DRS) is a potential supplement or alternative to the traditional time-consuming and costly combustion method of Ct analysis, especially in spatial or temporal studies where sample numbers are large. We investigate the use of the visible to near-infrared (VNIR) and mid-infrared (MIR) spectra of soils coupled with chemometric analysis to determine their Ct content. Our specific focus is on Hawaiian soils of agricultural importance. Though this technique has been introduced to the soil community, it has yet to be fully tested and used in practical applications for all soil types, and this is especially true for Hawaii. In short, DRS characterizes and differentiates materials based on the variation of the light reflected by a material at certain wavelengths. This spectrum is dependent on the material’s composition, structure, and physical state. Multivariate chemometric analysis unravels the information in a set of spectra that can help predict a property such as Ct. This study benefits from the remarkably diverse soils of Hawaii. Our sample set includes 216 soil samples from 145 pedons from the main Hawaiian Islands archived at the National Soil Survey Center in Lincoln, NE, along with more than 50 newly-collected samples from Kauai, Oahu, Molokai, and Maui. In total, over 90 series from 10 of the 12 soil orders are represented. The Ct values of these samples range from < 1% - 55%. We anticipate that the diverse nature of our sample set will ensure a model with applicability to a wide variety of soils, both in Hawaii and globally. We have measured the VNIR and MIR spectra of these samples and obtained their Ct values by dry combustion. Our initial analyses are conducted using only samples obtained from the Lincoln archive. In this

  12. Total Nitrogen and Available Phosphorus Dynamics in Soils ...

    African Journals Online (AJOL)

    Total nitrogen and available phosphorus concentration of soils in three secondary forest fields aged 1, 5 and 10 years of age regenerating from degraded abandoned rubber plantation (Hevea brasiliensis) and a mature forest in the west African Rainforest belt in southern Nigeria were investigated in order to determine the ...

  13. Total organic carbon in aggregates as a soil recovery indicator

    Science.gov (United States)

    Luciene Maltoni, Katia; Rodrigues Cassiolato, Ana Maria; Amorim Faria, Glaucia; Dubbin, William

    2015-04-01

    The soil aggregation promotes physical protection of organic matter, preservation of which is crucial to improve soil structure, fertility and ensure the agro-ecosystems sustainability. The no-tillage cultivation system has been considered as one of the strategies to increase total soil organic carbono (TOC) contents and soil aggregation, both are closely related and influenced by soil management systems. The aim of this study was to evaluate the distribution of soil aggregates and the total organic carbon inside aggregates, with regard to soil recovery, under 3 different soil management systems, i.e. 10 and 20 years of no-tillage cultivation as compared with soil under natural vegetation (Cerrado). Undisturbed soils (0-5; 5-10; and 10-20 cm depth) were collected from Brazil, Central Region. The soils, Oxisols from Cerrado, were collected from a field under Natural Vegetation-Cerrado (NV), and from fields that were under conventional tillage since 1970s, and 10 and 20 years ago were changed to no-tillage cultivation system (NT-10; NT-20 respectively). The undisturbed samples were sieved (4mm) and the aggregates retained were further fractionated by wet sieving through five sieves (2000, 1000, 500, 250, and 50 μm) with the aggregates distribution expressed as percentage retained by each sieve. The TOC was determined, for each aggregate size, by combustion (Thermo-Finnigan). A predominance of aggregates >2000 μm was observed under NV treatment (92, 91, 82 %), NT-10 (64, 73, 61 %), and NT-20 (71, 79, 63 %) for all three depths (0-5; 5-10; 10-20 cm). In addition greater quantities of aggregates in sizes 1000, 500, 250 and 50 μm under NT-10 and NT-20 treatments, explain the lower aggregate stability under these treatments compared to the soil under NV. The organic C concentration for NV in aggregates >2000 μm was 24,4; 14,2; 8,7 mg/g for each depth (0-5; 5-10; 10-20 cm, respectively), higher than in aggregates sized 250-50 μm (7,2; 5,5; 4,4 mg/g) for all depths

  14. Relationships between Hg Air-surface exchange, Soil Moisture and Precipitation at a Background Vegetated Site in South-Eastern Australia.

    Science.gov (United States)

    Macsween, K.; Edwards, G. C.

    2017-12-01

    Despite many decades of research, the controlling mechanisms of mercury (Hg) air-surface exhange are still poorly understood. Particularly in Australian ecosystems where there are few anthropogenic inputs. A clear understanding of these mechanisms is vital for accurate representation in the global Hg models, particularly regarding re-emission. Water is known to have a considerable influence on Hg exchange within a terrestrial ecosystem. Precipitation has been found to cause spikes is Hg emissions during the initial stages of rain event. While, Soil moisture content is known to enhance fluxes between 15 and 30% Volumetric soil water (VSW), above which fluxes become suppressed. Few field experiments exist to verify these dominantly laboratory or controlled experiments. Here we present work looking at Hg fluxes over an 8-month period at a vegetated background site. The aim of this study is to identify how changes to precipitation intensity and duration, coupled with variable soil moisture content may influence Hg flux across seasons. As well as the influence of other meteorological variables. Experimentation was undertaken using aerodynamic gradient micrometeorological flux method, avoiding disruption to the surface, soil moisture probes and rain gauge measurements to monitor alterations to substrate conditions. Meteorological and air chemistry variables were also measured concurrently throughout the duration of the study. During the study period, South-Eastern Australia experienced several intense east coast low storm systems during the Autumn and Spring months and an unusually dry winter. VSW rarely reached above 30% even following the intense rainfall experienced during the east coast lows. The generally dry conditions throughout winter resulted in an initial spike in Hg emissions when rainfall occurred. Fluxes decreased shortly after the rain began but remained slightly elevated. Given the reduced net radiation and cooler temperatures experienced during the winter

  15. 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.

  16. 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.

  17. PRESENCIA DEL HG TOTAL EN UNA RELACIÓN SUELO-PLANTA-ATMÓSFERA AL SUR DE LA SIERRA GORDA DE QUERÉTARO, MÉXICO

    Directory of Open Access Journals (Sweden)

    Gilberto Hernández-Silva

    2012-01-01

    Full Text Available La región minera de San Joaquín, Querétaro, México, tiene un historial de más de dos mil años de explotación. En ella se identificaron cuatro áreas con contenidos de Hg en suelos por arriba de lo permitido por la NOM y la WHO: Azogues y Ranas- San Joaquín (>300 mg kg-1 y Calabacillas-Santa Rita y La Lana (30.1-300 mg kg-1. Los suelos de estas áreas proporcionan al maíz (Zea mays, cantidades significativas de Hg total a través de mecanismos de traslocación (0.2-8.7 mg kg-1 en raíces y 0.2- 8.2 mg kg-1 en tallo y hoja; en grano, las cantidades oscilan entre 0.04-0.87 mg kg-1 (0.5 mg kg-1 es el máximo permitido. En la fracción insoluble del agua de lluvia, la concentración promedio fue de 67.47 μg L-1; en la fracción soluble se tuvo un promedio de 36.49 μg L-1. El promedio diario de vapor de Hg fue de 67 ng m-3 durante los 38 días de lectura, con un intervalo de 40 a 100 ng m-3, lo que demuestra una gran diferencia en la cantidad de volatilización del Hg. Los suelos, sedimentos y terreros de cinabrio, constituyen la fuente que provee de Hg al maíz a través de mecanismos de traslocación y material particulado hacia la atmósfera arrastrado por el viento y redepositado a sotavento. Las lecturas que se obtuvieron de vapor de Hg resultaron más altas de lo recomendable. Los resultados obtenidos en el sistema estudiado, denotan concentraciones por arriba del límite permisible. La población de San Joaquín está expuesta a una concentración de mercurio que es variable y por arriba de lo permitido, lo que puede tener serias consecuencias en la salud humana y el posible impacto en el medio ambiente.

  18. Feasibility study on the use of soil washing to remediate the As-Hg contamination at an ancient mining and metallurgy area.

    Science.gov (United States)

    Sierra, C; Menéndez-Aguado, J M; Afif, E; Carrero, M; Gallego, J R

    2011-11-30

    Soils in abandoned mining sites generally present high concentrations of trace elements, such as As and Hg. Here we assessed the feasibility of washing procedures to physically separate these toxic elements from soils affected by a considerable amount of mining and metallurgical waste ("La Soterraña", Asturias, NW Spain). After exhaustive soil sampling and subsequent particle-size separation via wet sieving, chemical and mineralogical analysis revealed that the finer fractions held very high concentrations of As (up to 32,500 ppm) and Hg (up to 1600 ppm). These elements were both associated mainly with Fe/Mn oxides and hydroxides. Textural and geochemical data were correlated with the geological substrate by means of a multivariate statistical analysis. In addition, the Hg liberation size (below 200 μm) was determined to be main factor conditioning the selection of suitable soil washing strategies. These studies were finally complemented with a specific-gravity study performed with a C800 Mozley separator together with a grindability test, both novel approaches in soil washing feasibility studies. The results highlighted the difficulties in treating "La Soterraña" soils. These difficulties are attributed to the presence of contaminants embedded in the soil and spoil heap aggregates, caused by the meteorization of gangue and ore minerals. As a result of these two characteristics, high concentrations of the contaminants accumulate in all grain-size fractions. Therefore, the soil washing approach proposed here includes the grinding of particles above 125 μm. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. 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.

  20. Hg contents in soils and olive-tree (Olea Europea, L.) leaves from an area affected by elemental mercury pollution (Jódar, SE Spain).

    Science.gov (United States)

    López-Berdonces, Miguel Angel; María Esbrí, José; Amorós, José Angel; Lorenzo, Saturnino; Fernández-Calderón, Sergio; Higueras, Pablo; Perez-de-los-Reyes, Caridad

    2014-05-01

    Data from soil and olive tree leaves around a decommissioned chlor-alkali plant are presented in this communication. The factory was active in the period 1977-1991, producing during these years a heavily pollution of Guadalquivir River and hydrargyrism in more than local 45 workers. It is located at 7 km South of Jódar, a locality with some 12,120 inhabitants. Mercury usage was general in this type of plants, but at present it is being replaced by other types of technologies, due to the risks of mercury usage in personal and environment. A soil geochemistry survey was carried out in the area, along with the analysis of olive-tree leaves (in the plots with this culture) from the same area. 73 soil samples were taken at two different depths (0-15 cm and 15-30 cm), together with 41 olive tree samples. Mercury content of geologic and biologic samples was determined by means of Atomic Absorption Spectrometry with Zeeman Effect, using a Lumex RA-915+ device with the RP-91C pyrolysis attachment. Air surveys were carried our using a RA-915M Lumex portable analytical device. Soil mercury contents were higher in topsoil than in the deeper soil samples, indicating that incorporation of mercury was due to dry and wet deposition of mercury vapors emitted from the plant. Average content in topsoil is 564.5 ng g-1. Hg contents in olive-tree leaves were in the range 46 - 453 ng g-1, with an average of 160.6 ng g-1. This level is slightly lower than tolerable level for agronomic crops established by Kabata-Pendias (2001) in 200 ng g-1. We have also compared soil and leaf contents for each sampling site, finding a positive and significant correlation (R=0.49), indicating that Hg contents in the leaves are linked to Hg contents in the soils. BAC (Bioaccumulation Absorption Coefficient, calculated as ratio between soil and leaf concentration) is 0.28 (consistent with world references, BAC = 0.7), considered "medium" in comparison with other mineral elements. Main conclusions of this

  1. Characterization of soils from an industrial complex contaminated with elemental mercury

    International Nuclear Information System (INIS)

    Miller, Carrie L.; Watson, David B.; Lester, Brian P.; Lowe, Kenneth A.; Pierce, Eric M.; Liang, Liyuan

    2013-01-01

    Historical use of liquid elemental mercury (Hg(0) l ) at the Y-12 National Security Complex in Oak Ridge, TN, USA, resulted in large deposits of Hg(0) l in the soils. The fate and distribution of the spilled Hg(0) are not well characterized. In this study we evaluated analytical tools for characterizing the speciation of Hg in the contaminated soils and then used the analytical techniques to examine the speciation of Hg in two soil cores collected at the site. These include x-ray fluorescence (XRF), soil Hg(0) headspace analysis, and total Hg determination by acid digestion coupled with cold vapor atomic absorption (HgT). XRF was not found to be suitable for evaluating Hg concentrations in heterogeneous soils containing low concentration of Hg or Hg(0) because Hg concentrations determined using this method were lower than those determined by HgT analysis and the XRF detection limit is 20 mg/kg. Hg(0) g headspace analysis coupled with HgT measurements yielded good results for examining the presence of Hg(0) l in soils and the speciation of Hg. The two soil cores are highly heterogeneous in both the depth and extent of Hg contamination, with Hg concentrations ranging from 0.05 to 8400 mg/kg. In the first core, Hg(0) l was distributed throughout the 3.2 m depth, whereas the second core, from a location 12 m away, contained Hg(0) l in a 0.3 m zone only. Sequential extractions showed organically associated Hg dominant at depths with low Hg concentration. Soil from the zone of groundwater saturation showed reducing conditions and the Hg is likely present as Hg-sulfide species. At this depth, lateral Hg transport in the groundwater may be a source of Hg detected in the soil at the deeper soil depths. Overall, characterization of soils containing Hg(0) l is difficult because of the heterogeneous distribution of Hg within the soils. This is exacerbated in industrial facilities where fill materials make up much of the soils and historical and continued reworking of the

  2. Correlation between Soil Organic Matter, Total Organic Matter and ...

    African Journals Online (AJOL)

    Michael Horsfall

    carbon (TOC) content, water content and soils texture for industrial area at Pengkalan Chepa, township of Kota ... soil erosion and geologic deposition processes (Tan et al., 2004). .... infiltration rate and consist of soils with layer that impedes ...

  3. Determination of total organic phosphorus in samples of mineral soils

    Directory of Open Access Journals (Sweden)

    Armi Kaila

    1962-01-01

    Full Text Available In this paper some observations on the estimation of organic phosphorus in mineral soils are reported. The fact is emphasized that the accuracy of all the methods available is relatively poor. Usually, there are no reasons to pay attention to differences less than about 20 ppm. of organic P. Analyses performed on 345 samples of Finnish mineral soils by the extraction method of MEHTA et. al. (10 and by a simple procedure adopted by the author (successive extractions with 4 N H2SO4 and 0.5 N NaOH at room temperature in the ratio of 1 to 100 gave, on the average, equal results. It seemed to be likely that the MEHTA method removed the organic phosphorus more completely than did the less vigorous method, but in the former the partial hydrolysis of organic phosphorus compounds tends to be higher than in the latter. An attempt was made to find out whether the differences between the respective values for organic phosphorus obtained by an ignition method and the simple extraction method could be connected with any characteristics of the soil. No correlation or only a low correlation coefficient could be calculated between the difference in the results of these two methods and e. g. the pH-value, the content of clay, organic carbon, aluminium and iron soluble in Tamm’s acid oxalate, the indicator of the phosphate sorption capacity, or the »Fe-bound» inorganic phosphorus, respectively. The absolute difference tended to increase with an increase in the content of organic phosphorus. For the 250 samples of surface soils analyzed, the ignition method gave values which were, on the average, about 50 ppm. higher than the results obtained by the extraction procedure. The corresponding difference for the 120 samples from deeper layers was about 20 ppm of organic P. The author recommends, for the present, the determination of the total soil organic phosphorus as an average of the results obtained by the ignition method and the extraction method.

  4. Mercury in the soil of two contrasting watersheds in the eastern United States

    Science.gov (United States)

    Burns, Douglas A.; Woodruff, Laurel G.; Bradley, Paul M.; Cannon, William F.

    2014-01-01

    Soil represents the largest store of mercury (Hg) in terrestrial ecosystems, and further study of the factors associated with soil Hg storage is needed to address concerns about the magnitude and persistence of global environmental Hg bioaccumulation. To address this need, we compared total Hg and methyl Hg concentrations and stores in the soil of different landscapes in two watersheds in different geographic settings with similar and relatively high methyl Hg concentrations in surface waters and biota, Fishing Brook, Adirondack Mountains, New York, and McTier Creek, Coastal Plain, South Carolina. Median total Hg concentrations and stores in organic and mineral soil samples were three-fold greater at Fishing Brook than at McTier Creek. Similarly, median methyl Hg concentrations were about two-fold greater in Fishing Brook soil than in McTier Creek soil, but this difference was significant only for mineral soil samples, and methyl Hg stores were not significantly different among these watersheds. In contrast, the methyl Hg/total Hg ratio was significantly greater at McTier Creek suggesting greater climate-driven methylation efficiency in the Coastal Plain soil than that of the Adirondack Mountains. The Adirondack soil had eight-fold greater soil organic matter than that of the Coastal Plain, consistent with greater total Hg stores in the northern soil, but soil organic matter – total Hg relations differed among the sites. A strong linear relation was evident at McTier Creek (r2 = 0.68; p2 = 0.13; phighly variable across the soil organic matter content range, suggesting excess Hg binding capacity in the Adirondack soil. These results suggest greater total Hg turnover time in Adirondack soil than that of the Coastal Plain, and that future declines in stream water Hg concentrations driven by declines in atmospheric Hg deposition will be more gradual and prolonged in the Adirondacks.

  5. Use of INAA in the preparation of a set soil Reference Materials with certified values of total element contents

    International Nuclear Information System (INIS)

    Kucera, J.; Horakova, J.; Soukal, L.

    1997-01-01

    A set of certified Reference Materials was prepared consisting of four natural agricultural soils with normal (n) and elevated (e) levels of element contents: CRM 7001 Light Sandy Soil (n), CRM 7002 Light Sandy Soil (e), CRM 7003 Silty Clay Loam (n), and CRM 7004 Loam (e). In these materials, certified and/or information values of the total contents of the elements As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V and Zn, and their fractions extractable by aqua regia, boiling and cold 2M nitric acid were derived from an interlaboratory comparison in which 28 laboratories participated. Highly precise and accurate procedures of instrumental neutron activation analysis (INAA) were employed for homogeneity testing and also for certification of the total element contents. For comparation purposes, NIST SRM-2704 Buffalo River Sediment was analyzed by INAA, as well. The INAA results obtained compared very well with the certified and/or information values for four soil CRMs and also with NIST values for SRM-2704. From this agreement, a very high reliability of the new soil CRMs can be inferred. (author)

  6. Method Performance of Total Mercury (Hg) Testing in the Biological Samples by Using Cold Vapour Atomic Absorption Spectrophotometer (CV-AAS)

    International Nuclear Information System (INIS)

    Susanna TS; Samin

    2007-01-01

    Method performance (validation) of total mercury (Hg) testing in the biological samples by using cold vapour atomic absorption spectrophotometer (CV-AAS) has been done. The objective of this research is to know the method performance of CV-AAS as one of points for the accreditation testing of laboratory according IS0/IEC 17025-2005. The method performance covering limit of detection (LOD), accuracy, precision and bias. As a standard material used SRM Oyster Tissue 15660 from Winopal Forshung Germany, whereas the biological samples were human hair. In principle of mercury testing for solid samples using CV-AAS is dissolving this sample and standard with 10 mL HNO 3 supra pure into a closed quartz tube and heating at 150 °C for 4 hours. The concentration of mercury in each samples was determined at the condition of operation were stirring time (T 1 ) 70 seconds, delay time (T 2 ) 15 seconds, heating time (T 3 ) 13 seconds and cooling time (T 4 ) of 25 seconds. Mercury ion in samples are reduced with SnCl 2 10 % in H 2 SO 4 20 %, and then the vapour of mercury from reduction is passed in NaOH 20 % solution and aquatridest. The result of method performance were: limit of detection (LOD) = 0.085 ng, accuracy 99.70 %, precision (RSD) = 1.64 % and bias = 0.30 %. From the validation result showed that the content of mercury total was in the range of certified values. The total mercury content (Hg) in human hair were varied from 406.93 - 699.07 ppb. (author)

  7. Mercury content in volcanic soils across Europe and its relationship with soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Rodriguez, Susana; Fernandez-Calvino, David; Arias-Estevez, Manuel; Novoa-Munoz, Juan Carlos [Vigo Univ., Ourense (Spain). Area de Edafoloxia e Quimica Agricola; Pontevedra-Pombal, Xabier; Taboada, Teresa; Martinez-Cortizas, Antonio; Garcia-Rodeja, Eduardo [Universidad de Santiago, Coruna (Spain). Dept. Edafoloxia e Quimica Agricola

    2012-04-15

    Volcanoes are a natural source of Hg, whose deposition can occur in neighbouring soils. This study examines the role of soil compounds in the geochemical behaviour of total Hg (Hg{sub T}) in volcanic soils. An estimation of Hg from lithological origin is also assessed to ascertain the relevance of other sources in Hg{sub T} accumulated in volcanic soils. Twenty soil profiles developed from volcanic materials and located across European volcanic regions were selected for this study. The general characterisation of soils included total C, N and S content and Al and Fe distribution determined using traditional methods. The total content of major and trace elements was determined using X-ray fluorescence spectrometry (XRF). The total Hg content of soil samples was measured with atomic absorption spectroscopy using a solid sample Hg analyser. Lithogenic Hg was calculated in the uppermost soil considering Al, Ti and Zr as conservative reference elements. Several statistical analyses (Pearson correlations, Mann-Whitney tests, stepwise multiple regressions and analysis of variance) were carried to ascertain the role of soil parameters and characteristics in the Hg accumulation in volcanic soils. The total Hg ranged from 3.0 to 640 ng g{sup -1} and it tended to diminish with soil depth except in some soils where the lithological discontinuities resulted in high values of Hg{sub T} in the Bw horizons. More than 75% of the Hg{sub T} variance could be attributed to distinct contents of organic matter, Al- and Fe-humus complexes and inorganic non-crystalline Al and Fe compounds in ''andic'', ''vitric'' and ''non-andic'' horizons. The degree of pedogenetic soil evolution notably influenced the Hg{sub T} soil content. Lithogenic Hg (1.6-320 ng g{sup -1}) was correlated with Al-humus complexes and clay content, suggesting the relevance of pedogenetic processes, whereas exogenic Hg (1.4-180 ng g{sup -1}) was correlated

  8. Impact of total organic carbon (in sediments) and dissolved organic carbon (in overlying water column) on Hg sequestration by coastal sediments from the central east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Chakrabortya, P.; Sharma, B.M.; Babu, P.V.R.; Yao, K.M.; Jaychandran, S.

    , 1991; Liu et al., 2006; Tack and Verloo, 1995). Mercury accumulates in sediment globally from many physical, chemical, biological, geological and anthropogenic environmental processes. Thus, sediment can be a good indicator of water quality of a...-Black method (Schumacher, 2002). This method has been widely used for the determination of total organic carbon in the soil and sediments. 3.0 Results and discussion The general description and texture analysis of the studied sediments are presented...

  9. Determination of total selenium and selenium distribution in the milk phases in commercial cow's milk by HG-AAS

    Energy Technology Data Exchange (ETDEWEB)

    Muniz-Naveiro, Oscar; Dominguez-Gonzalez, Raquel; Bermejo-Barrera, Adela; Bermejo-Barrera, Pilar [University of Santiago de Compostela, Department of Analytical Chemistry, Nutrition and Bromatology, Santiago de Compostela (Spain); Cocho, Jose A. [University Clinical Hospital, Laboratory of Metabolic and Nutritional Disorders, Santiago de Compostela (Spain); Fraga, Jose M. [University Clinical Hospital, Department of Pediatrics, Santiago de Compostela (Spain)

    2005-03-01

    A procedure has been developed for determining the selenium in cow's milk using hydride generation-atomic absorption spectrometry (HG-AAS) following microwave-assisted acid digestion. The selenium distributions in milk whey, fat and micellar casein phases were studied after separating the different phases by ultracentrifugation and determining the selenium in all of them. The detection limits obtained by HG-AAS for the whole milk, milk whey and micellar casein were 0.074, 0.065 and 0.075 {mu}g l{sup -1}, respectively. The accuracy for the whole milk was checked by using a Certified Reference Material CRM 8435 whole milk powder from NIST, and the analytical recoveries for the milk whey and casein micelles were 100.9 and 96.9%, respectively. A mass balance study of the determination of selenium in the different milk phases was carried out, obtaining values of 95.5-100.8%. The total content of selenium was determined in 37 milk samples from 15 different manufacturers, 19 whole milk samples and 18 skimmed milk samples. The selenium levels found were within the 8.5-21 {mu}g l{sup -1} range. The selenium distributions in the different milk phases were studied in 14 whole milk samples, and the highest selenium levels were found in milk whey (47.2-73.6%), while the lowest level was found for the fat phase (4.8-16.2%). A strong correlation was found between the selenium levels in whole milk and the selenium levels in the milk components. (orig.)

  10. Total carbon and nitrogen in the soils of the world

    NARCIS (Netherlands)

    Batjes, N.H.

    2014-01-01

    The soil is important in sequestering atmospheric CO2 and in emitting trace gases (e.g. CO2, CH4 and N2O) that are radiatively active and enhance the ‘greenhouse’ effect. Land use changes and predicted global warming, through their effects on net primary productivity, the plant community and soil

  11. The organic contamination level based on the total soil mass is not a proper index of the soil contamination intensity

    Science.gov (United States)

    Hung, H.-W.; Daniel, Sheng G.; Lin, T.-F.; Su, Y.; Chiou, C.T.

    2009-01-01

    Concentrations of organic contaminants in common productive soils based on the total soil mass give a misleading account of actual contamination effects. This is attributed to the fact that productive soils are essentially water-saturated, with the result that the soil uptake of organic compounds occurs principally by partition into the soil organic matter (SOM). This report illustrates that the soil contamination intensity of a compound is governed by the concentration in the SOM (Com) rather than by the concentration in whole soil (Cs). Supporting data consist of the measured levels and toxicities of many pesticides in soils of widely differing SOM contents and the related levels in in-situ crops that defy explanation by the Cs values. This SOM-based index is timely needed for evaluating the contamination effects of food crops grown in different soils and for establishing a dependable priority ranking for intended remediation of numerous contamination sites.

  12. Influence of soil mercury concentration and fraction on bioaccumulation process of inorganic mercury and methylmercury in rice (Oryza sativa L.).

    Science.gov (United States)

    Zhou, Jun; Liu, Hongyan; Du, Buyun; Shang, Lihai; Yang, Junbo; Wang, Yusheng

    2015-04-01

    Recent studies showed that rice is the major pathway for methylmercury (MeHg) exposure to inhabitants in mercury (Hg) mining areas in China. There is, therefore, a concern regarding accumulation of Hg in rice grown in soils with high Hg concentrations. A soil pot experimental study was conducted to investigate the effects of Hg-contaminated soil on the growth of rice and uptake and speciation of Hg in the rice. Our results imply that the growth of rice promotes residual fraction of Hg transforming to organic-bound fraction in soil and increased the potential risks of MeHg production. Bioaccumulation factors deceased for IHg but relatively stabilized for MeHg with soil total mercury (THg) increasing. IHg in soil was the major source of Hg in the root and stalk, but leaf was contributed by Hg from both atmosphere and soil. Soluble and exchangeable Hg fraction can predict the bioavailability of IHg and MeHg in soils, and that can provide quantitative description of the rate of uptake of the bioavailable Hg. Soluble and exchangeable Hg fraction in paddy soil exceeding 0.0087 mg kg(-1) may cause THg concentration in rice grain above the permissible limit standard, and MeHg concentration in paddy soil more than 0.0091 mg kg(-1) may have the health risks to humans.

  13. Just passing through --- high Hg deposition to Puerto Rico forest moves quickly off the landscape

    Science.gov (United States)

    Shanley, J. B.; Willenbring, J. K.; Kaste, J. M.; Occhi, M.; McDowell, W. H.

    2012-12-01

    Atmospheric mercury (Hg) in wet deposition at the Luquillo Experimental Forest in northeastern Puerto Rico, averages 28 μg m-2 yr-1, higher than any site in the USA Mercury Deposition Network. Despite the high deposition, Hg content of soils, vegetation, and biota are below global averages. The low Hg content of watershed surfaces, coupled with exceptionally high stream total Hg flux, suggest that most of the Hg passes through the watershed with minimal retention. We assessed Hg dynamics in two adjacent watersheds, Rio Icacos underlain by quartz diorite, and Rio Mameyes underlain by volcaniclastic rocks. At both sites, high-flow Hg concentrations approached 100 ng L-1, dominated by particulate Hg. In order to assess the apparent pass-through nature of Hg in this tropical forest, we measured 7Be and 10Be isotopes from natural, cosmogenic fallout adsorbed on stream suspended particles to constrain the Hg age /residence time and source (atmospheric vs. geogenic or legacy Hg from 19th century gold mining). Ubiquitous 7Be (half-life 53 days) and relatively high 7Be/10Be ratios on suspended particles suggest that stream Hg was dominated by erosion from exposed surfaces, supporting a short residence time. The low watershed retention of the high Hg throughput limits adverse biological effects in this tropical ecosystem.

  14. Teores de As, Pb, Cd e Hg e fertilidade de solos da região do Vale do Alto Guaporé, sudoeste do estado de Mato Grosso Contents of As, Pb, Cd e Hg and fertility of soils of Vale do Alto Guapore region, south-west of Mato Grosso state

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Pereira Pierangeli

    2009-03-01

    Full Text Available O diagnóstico da fertilidade e teores de elementos-traço (ETs em solos é importante, pois estes dados são escassos na literatura para áreas de transição Pantanal-Cerrado-Floresta Amazônica. Esse trabalho avaliou diversos parâmetros relacionados à fertilidade, teores biodisponíveis de Fe, Mn, Zn, Cu e B e semitotais de As, Cd, Hg e Pb de solos do Vale do Alto Guaporé, região sudoeste do estado de Mato Grosso. Foram coletadas amostras de solos (0-0,20 e 0,20-0,40 m de profundidade em áreas de vegetação nativa (VN, pastagem (AP, cultura anual (CA e garimpo de ouro (G. As amostras foram analisadas conforme métodos de rotina para avaliação da fertilidade do solo e ETs pelo método SW-3051A e os resultados médios comparados com os valores de referência de qualidade (VRQ para solos estipulados pela Companhia de Tecnologia de Saneamento Ambiental (CETESB. Teores mais elevados de As e Hg foram verificados em VN e G com médias, respectivamente, iguais a 43,9 e 101,13 para o As; e 0,12 e 0,14 mg kg-1 para o Hg. Exceto Pb, vários locais de amostragem apresentaram teores dos ETs superiores ao VRQ: 46% em VN; 60% em G; 28% em CA; e 44% em AP, para o As; 20,8; 50; 55; e 22% em VN, G, CA e AP, respectivamente, para o Cd; 75; 65 e 67% das áreas de VN, G e CA e AP, respectivamente, para o Hg. A saturação por bases foi alta (60-80% em 51,5% das amostras, enquanto o P foi baixo em todas áreas. Valores de referência de qualidade de solo para o As e Hg devem ser estipulados para solos dessa região, tendo em vista que os teores observados em áreas nativas foram superiores ao VRQ.The fertility and trace elements diagnosis of soils is important for agricultural and environmental purposes, because there is little data available on the Pantanal-Cerrado-Floresta Amazônica transitional areas. This work evaluated many parameters relative to the fertility, Fe, Mn, Zn, Cu and B bioavailability, and total content of As, Cd, Hg and Pb in soils of

  15. 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

  16. Distribution of free and total aluminium in some cocoa-growing soils ...

    African Journals Online (AJOL)

    The Western Region of Ghana is currently carrying the bulk of Ghana's cocoa, and so it is important to investigate the amounts and distribution of total and free Al oxides in some cocoa-growing soils from the region. Six soil series belonging to one major compound association of soils occurring in a toposequence, the ...

  17. [Correlation analysis of nutrients and microorganisms in soils with polyphenols and total flavonoids of Houttuynia cordata].

    Science.gov (United States)

    Wu, Dan; Luo, Shi-qiong; Yang, Zhan-nan; Ma, Jing; Hong, Liang

    2015-04-01

    The relationship of nutrients and microorganisms in soils with polyphenols and total flavonoids of Houttuynia cordata were investigated by measuring nutrients, enzyme activity, pH, concentrations of microbe phospholipid fatty acids (PLFAs) in soils, and determining concentrations of polyphenols and total flavonoids of H. cordata. The research is aimed to understand characteristics of the planting soils and improve the quality of cultivated H. cordata. The soils at different sample sites varied greatly in nutrients, enzyme activity, pH, microbic PLFAs and polyphenols and all flavonoids. The content of total PLFAs in sample sites was following: bacteria > fungi > actinomyces > nematode. The content of bacteria PLFAs was 37.5%-65.0% at different sample sites. Activities of polyphenol oxidease, concentrations of available P and content of PLFAs of bacteria, actinomyces and total microorganisms in soils were significantly and positively related to the concentrations of polyphenols and total flavonoids of H. cordata, respectively (P soils was significantly and negatively related to concentrations of polyphenols and total flavonoids of H. cordata, respectively (P soil nutrient, which may be improved due to transformation of soil microorganisms and enzymes to N and P in the soils, was beneficial to adaptation of H. cordata adapted to different soil conditions, and significantly affects metabolic accumulation of polyphenols and flavonoids of H. cordata.

  18. 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

  19. 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.

  20. Study of systematic errors in the determination of total Hg levels in the range -5% in inorganic and organic matrices with two reliable spectrometrical determination procedures

    International Nuclear Information System (INIS)

    Kaiser, G.; Goetz, D.; Toelg, G.; Max-Planck-Institut fuer Metallforschung, Stuttgart; Knapp, G.; Maichin, B.; Spitzy, H.

    1978-01-01

    In the determiniation of Hg at ng/g and pg/g levels systematic errors are due to faults in the analytical methods such as intake, preparation and decomposition of a sample. The sources of these errors have been studied both with 203 Hg-radiotracer techniques and two multi-stage procedures developed for the determiniation of trace levels. The emission spectrometrie (OES-MIP) procedure includes incineration of the sample in a microwave induced oxygen plasma (MIP), the isolation and enrichment on a gold absorbent and its excitation in an argon plasma (MIP). The emitted Hg-radiation (253,7 nm) is evaluated photometrically with a semiconductor element. The detection limit of the OES-MIP procedure was found to be 0,01 ng, the coefficient of variation 5% for 1 ng Hg. The second procedure combines a semi-automated wet digestion method (HCLO 3 /HNO 3 ) with a reduction-aeration (ascorbic acid/SnCl 2 ), and the flameless atomic absorption technique (253,7 nm). The detection limit of this procedure was found to be 0,5 ng, the coefficient of variation 5% for 5 ng Hg. (orig.) [de

  1. Sustainable remediation of mercury contaminated soils by thermal desorption.

    Science.gov (United States)

    Sierra, María J; Millán, Rocio; López, Félix A; Alguacil, Francisco J; Cañadas, Inmaculada

    2016-03-01

    Mercury soil contamination is an important environmental problem that needs the development of sustainable and efficient decontamination strategies. This work is focused on the application of a remediation technique that maintains soil ecological and environmental services to the extent possible as well as search for alternative sustainable land uses. Controlled thermal desorption using a solar furnace at pilot scale was applied to different types of soils, stablishing the temperature necessary to assure the functionality of these soils and avoid the Hg exchange to the other environmental compartments. Soil mercury content evolution (total, soluble, and exchangeable) as temperature increases and induced changes in selected soil quality indicators are studied and assessed. On total Hg, the temperature at which it is reduced until acceptable levels depends on the intended soil use and on how restrictive are the regulations. For commercial, residential, or industrial uses, soil samples should be heated to temperatures higher than 280 °C, at which more than 80 % of the total Hg is released, reaching the established legal total Hg level and avoiding eventual risks derived from high available Hg concentrations. For agricultural use or soil natural preservation, conversely, maintenance of acceptable levels of soil quality limit heating temperatures, and additional treatments must be considered to reduce available Hg. Besides total Hg concentration in soils, available Hg should be considered to make final decisions on remediation treatments and potential future uses. Graphical Abstract Solar energy use for remediation of soils affected by mercury.

  2. Spatial analysis and hazard assessment on soil total nitrogen in the middle subtropical zone of China

    Science.gov (United States)

    Lu, Peng; Lin, Wenpeng; Niu, Zheng; Su, Yirong; Wu, Jinshui

    2006-10-01

    Nitrogen (N) is one of the main factors affecting environmental pollution. In recent years, non-point source pollution and water body eutrophication have become increasing concerns for both scientists and the policy-makers. In order to assess the environmental hazard of soil total N pollution, a typical ecological unit was selected as the experimental site. This paper showed that Box-Cox transformation achieved normality in the data set, and dampened the effect of outliers. The best theoretical model of soil total N was a Gaussian model. Spatial variability of soil total N at NE60° and NE150° directions showed that it had a strip anisotropic structure. The ordinary kriging estimate of soil total N concentration was mapped. The spatial distribution pattern of soil total N in the direction of NE150° displayed a strip-shaped structure. Kriging standard deviations (KSD) provided valuable information that will increase the accuracy of total N mapping. The probability kriging method is useful to assess the hazard of N pollution by providing the conditional probability of N concentration exceeding the threshold value, where we found soil total N>2.0g/kg. The probability distribution of soil total N will be helpful to conduct hazard assessment, optimal fertilization, and develop management practices to control the non-point sources of N pollution.

  3. 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.)

  4. Evaluation and development of soil values for the pathway 'soil to plant'. Significance of mercury evaporation for the burden of plants; Ueberpruefung und Fortentwicklung der Bodenwerte fuer den Boden-Pflanze-Pfad. Teilbericht 2: Evaporation von Quecksilber aus kontaminierten Boeden und deren Bedeutung fuer die Hg-Aufnahme von Kulturpflanzen

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, K; Gaeth, S

    2001-10-01

    In cooperation with the Ad-hoc working group 'Transfer of heavy metals from soil to plant' of the Laenderarbeitsgemeinschaft Bodenschutz (LABO) the significance of mercury evaporation for the deduction of threshold values in respect of the impact via the pathway soil to plant was investigated. Mercury contamination of food- and feeding stuff plants was examined with special emphasis. For these purposes a lab experiment including three different soils with varying initial mercury load (background level, geogenic and anthropogenic contamination) and two different plant species (parsley and spinach) was carried out under defined conditions in closed lysimeters. Mercury uptake via the roots was minimised since the plants grew in isolated customary substrate which showed a low concentration of mercury. Thus, only the surrounding soil evaporated mercury. The concentrations of mercury in the plants in the background level treatment (0.1 mg Hg/kg dry soil) were 0.15 mg/kg dry matter (spinach). The treatment with anthropogenic contaminated soil (111 mg Hg/kg dry soil) resulted in concentrations in the two plants of 2.0 and 2.6 mg/kg dry matter, respectively. A comparable order of magnitude was achieved in the geogenic contaminated treatment (34 mg Hg/kg dry soil) with 2.1 mg/kg dry matter (spinach) and 0.44 mg/kg dry matter (parsley). Experiments conducted with radioactive {sup 203}Hg showed in each case Hg-tracer in the leaves, in the stem and in the roots, indicating a translocation within the plant from leaf to root. By means of a comprehensive literature study the state of the art for Hg-evaporation and Hg-uptake of plants was compiled. Comparing the experimental results with data derived from literature, the Hg-concentrations found are confirmed by results of other authors. (orig.) [German] In fachlicher Zusammenarbeit mit der Ad-hoc-Arbeitsgruppe 'Schwermetalltransfer Boden/Pflanze' der Laenderarbeitsgemeinschaft Bodenschutz (LABO) wurde fuer die Ableitung von Pruef

  5. Evaluation and development of soil values for the pathway 'soil to plant'. Significance of mercury evaporation for the burden of plants; Ueberpruefung und Fortentwicklung der Bodenwerte fuer den Boden-Pflanze-Pfad. Teilbericht 2: Evaporation von Quecksilber aus kontaminierten Boeden und deren Bedeutung fuer die Hg-Aufnahme von Kulturpflanzen

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, K.; Gaeth, S.

    2001-10-01

    In cooperation with the Ad-hoc working group 'Transfer of heavy metals from soil to plant' of the Laenderarbeitsgemeinschaft Bodenschutz (LABO) the significance of mercury evaporation for the deduction of threshold values in respect of the impact via the pathway soil to plant was investigated. Mercury contamination of food- and feeding stuff plants was examined with special emphasis. For these purposes a lab experiment including three different soils with varying initial mercury load (background level, geogenic and anthropogenic contamination) and two different plant species (parsley and spinach) was carried out under defined conditions in closed lysimeters. Mercury uptake via the roots was minimised since the plants grew in isolated customary substrate which showed a low concentration of mercury. Thus, only the surrounding soil evaporated mercury. The concentrations of mercury in the plants in the background level treatment (0.1 mg Hg/kg dry soil) were 0.15 mg/kg dry matter (spinach). The treatment with anthropogenic contaminated soil (111 mg Hg/kg dry soil) resulted in concentrations in the two plants of 2.0 and 2.6 mg/kg dry matter, respectively. A comparable order of magnitude was achieved in the geogenic contaminated treatment (34 mg Hg/kg dry soil) with 2.1 mg/kg dry matter (spinach) and 0.44 mg/kg dry matter (parsley). Experiments conducted with radioactive {sup 203}Hg showed in each case Hg-tracer in the leaves, in the stem and in the roots, indicating a translocation within the plant from leaf to root. By means of a comprehensive literature study the state of the art for Hg-evaporation and Hg-uptake of plants was compiled. Comparing the experimental results with data derived from literature, the Hg-concentrations found are confirmed by results of other authors. (orig.) [German] In fachlicher Zusammenarbeit mit der Ad-hoc-Arbeitsgruppe 'Schwermetalltransfer Boden/Pflanze' der Laenderarbeitsgemeinschaft Bodenschutz (LABO) wurde fuer die

  6. Mercury in stream water at five Czech catchments across a Hg and S deposition gradient

    Science.gov (United States)

    Navrátil, Tomáš; Shanley, James B.; Rohovec, Jan; Oulehle, Filip; Krám, Pavel; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria

    2015-01-01

    The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0 ng L− 1. The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3 μg m− 2 yr− 1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90 ng mg− 1. The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories.

  7. Total and available heavy metal concentrations in soils of the Thriassio plain (Greece) and assessment of soil pollution indexes.

    Science.gov (United States)

    Massas, Ioannis; Kalivas, Dionisios; Ehaliotis, Constantions; Gasparatos, Dionisios

    2013-08-01

    The Thriassio plain is located 25 km west of Athens city, the capital of Greece. Two major towns (Elefsina and Aspropyrgos), heavy industry plants, medium to large-scale manufacturing, logistics plants, and agriculture comprise the main land uses of the studied area. The aim of the present study was to measure the total and available concentrations of Cr, Zn, Ni, Pb, Co, Mn, Ba, Cu, and Fe in the top soils of the plain, and to asses soil contamination by these metals by using the geoaccumulation index (I geo), the enrichment factor (EF), and the availability ratio (AR) as soil pollution indexes. Soil samples were collected from 90 sampling sites, and aqua regia and DTPA extractions were carried out to determine total and available metal forms, respectively. Median total Cr, Zn, Ni, Pb, Co, Mn, Ba, Cu, and Fe concentrations were 78, 155, 81, 112, 24, 321, 834, 38, and 16 × 10(3) mg kg(-1), respectively. The available fractions showed much lower values with medians of 0.4, 5.6, 1.7, 6.9, 0.8, 5.7, 19.8, 2.1, and 2.9 mg kg(-1). Though median total metal concentrations are not considered as particularly high, the I geo and the EF values indicate moderate to heavy soil enrichment. For certain metals such as Cr, Ni, Cu, and Ba, the different distribution patterns between the EFs and the ARs suggest different origin of the total and the available metal forms. The evaluation of the EF and AR data sets for the soils of the two towns further supports the argument that the EFs can well demonstrate the long-term history of soil pollution and that the ARs can adequately portray the recent history of soil pollution.

  8. Evaluation the total exposure of soil sample in Adaya site and the obtain risk assessments for the worker by Res Rad code program

    International Nuclear Information System (INIS)

    Mahadi, A. M.; Khadim, A. A. N.; Ibrahim, Z. H.; Ali, S. A.

    2012-12-01

    The present study aims to evaluation the total exposure to the worker in Adaya site risk assessment by using Res Rad code program. The study including 5 areas soil sample calculate in the site and analysis it by High Pure Germaniums (Hg) system made (CANBERRA) company. The soil sample simulation by (Res Rad) code program by inter the radioactive isotope concentration and the specification of the contamination zone area, depth and the cover depth of it. The total exposure of same sample was about 9 mSv/year and the (Heast 2001 Morbidity, FGR13 Morbidity) about 2.045 state every 100 worker in the year. There are simple different between Heast 2001 Morbidity and FGR13 Morbidity according to the Dose Conversion Factor (DCF) use it. The (FGR13 Morbidity) about 2.041 state every 100 worker in the year. (Author)

  9. Relationship Between Total and Biaccessible Lead on Children's Blood Lead Levles in Urban Residential Philadelphia Soils.

    Data.gov (United States)

    U.S. Environmental Protection Agency — Relationship Between Total and Biaccessible Lead on Children's Blood Lead Levles in Urban Residential Philadelphia Soils. This dataset is not publicly accessible...

  10. Vertical profile measurements of soil air suggest immobilization of gaseous elemental mercury in mineral soil.

    Science.gov (United States)

    Obrist, Daniel; Pokharel, Ashok K; Moore, Christopher

    2014-02-18

    Evasion of gaseous elemental Hg (Hg(0)g) from soil surfaces is an important source of atmospheric Hg, but the volatility and solid-gas phase partitioning of Hg(0) within soils is poorly understood. We developed a novel system to continuously measure Hg(0)g concentrations in soil pores at multiple depths and locations, and present a total of 297 days of measurements spanning 14 months in two forests in the Sierra Nevada mountains, California, U.S. Temporal patterns showed consistent pore Hg(0)g concentrations below levels measured in the atmosphere (termed Hg(0)g immobilization), ranging from 66 to 94% below atmospheric concentrations throughout multiple seasons. The lowest pore Hg(0)g concentrations were observed in the deepest soil layers (40 cm), but significant immobilization was already present in the top 7 cm. In the absence of sinks or sources, pore Hg(0)g levels would be in equilibrium with atmospheric concentrations due to the porous nature of the soil matrix and gas diffusion. Therefore, we explain decreases in pore Hg(0)g in mineral soils below atmospheric concentrations--or below levels found in upper soils as observed in previous studies--with the presence of an Hg(0)g sink in mineral soils possibly related to Hg(0)g oxidation or other processes such as sorption or dissolution in soil water. Surface chamber measurements showing daytime Hg(0)g emissions and nighttime Hg(0)g deposition indicate that near-surface layers likely dominate net atmospheric Hg(0)g exchange resulting in typical diurnal cycles due to photochemcial reduction at the surface and possibly Hg(0)g evasion from litter layers. In contrast, mineral soils seem to be decoupled from this surface exchange, showing consistent Hg(0)g uptake and downward redistribution--although our calculations indicate these fluxes to be minor compared to other mass fluxes. A major implication is that once Hg is incorporated into mineral soils, it may be unlikely subjected to renewed Hg(0)g re-emission from

  11. Assessment of Pb, Cd and Hg soil contamination and its potential to cause cytotoxic and genotoxic effects in human cell lines (CaCo-2 and HaCaT).

    Science.gov (United States)

    Sljivic Husejnovic, Maida; Bergant, Martina; Jankovic, Sasa; Zizek, Suzana; Smajlovic, Aida; Softic, Adaleta; Music, Omer; Antonijevic, Biljana

    2018-01-23

    Soil contamination by heavy metals is a serious global environmental problem, especially for developing countries. A large number of industrial plants, which continually pollute the environment, characterize Tuzla Canton, Bosnia and Herzegovina. The aim of this study was to assess the level of soil pollution by heavy metals and to estimate cytotoxicity and genotoxicity of soil leachates from this area. Lead (Pb), cadmium (Cd) and mercury (Hg) were analyzed by ICP-AES and AAS. Soil contamination was assessed using contamination factor, degree of contamination, geoaccumulation index and pollution load index. To determine the connection of variables and understanding their origin in soils, principal component analysis (PCA) and cluster analysis (CA) were used. The results indicate that Cd and Hg originated from natural and anthropogenic activities, while Pb is of anthropogenic origin. For toxicity evaluation, CaCo-2 and HaCaT cells were used. PrestoBlue assay was used for cytotoxicity testing, and γH2A.X for genotoxicity evaluation. Concerning cytotoxicity, Cd and Hg had a positive correlation with cytotoxicity in HaCaT cells, but only Hg induced cytotoxicity in CaCo-2 cells. We also demonstrate that soil leachates contaminated by heavy metals can induce genotoxicity in both used cell lines. According to these results, combining bioassays with standard physicochemical analysis can be useful for evaluating environmental and health risks more accurately. These results are important for developing proper management strategies to decrease pollution. This is one of the first studies from this area and an important indication of soil quality in Southeast Europe.

  12. STUDY CONCERNING THE POSSIBILITY OF GAMMA-SPECTROSCOPY METHOD TO DETERMINE THE TOTAL POTASSIUM IN SOILS

    Directory of Open Access Journals (Sweden)

    Tamara Leah

    2011-12-01

    Full Text Available It was proved the possibility of determination the total potassium in soils by gamma-spectroscopic method with subsequent calculation of total potassium content in according to value of 40K isotope (expressed in Becquerel, Bq, using the formula: К2О, % = С . А, where: C – conversion coefficient, A – activity of isotope 40K in soil, Bq/kg. Conversion coefficient for chernozems of Moldova – C=0,00337.

  13. Cu accumulation by Lumbricus rubellus as affected by total amount of Cu in soil, soil moisture and soil heterogeneity.

    NARCIS (Netherlands)

    Marinussen, M.P.J.C.; Zee, van der S.E.A.T.M.

    1997-01-01

    To investigate the effect of soil heterogeneity on accumulation of pollutants in a contaminated soil by earthworms, we performed experiments under laboratory conditions with soil from a Cu-contaminated site, followed by experiments under field conditions. The first experiments were set up as a

  14. Total and Available Heavy Metal Concentrations and Assessment of Soil Pollution Indices in Selected Soils of Zanjan

    Directory of Open Access Journals (Sweden)

    M. Taheri

    2017-01-01

    Full Text Available Introduction: Soil is a hardly renewable natural resource. Although soil degradation, caused by either human activities and natural processes is a relatively slow procedure, but its effects are long lasting and most often, irreversible in the time scale of man's life. Among the most significant soil contaminants resulting from both natural and human sources, heavy metals are more important due to their long- term toxicity effects. For evaluating soil's enrichment rate by heavy metals, a wide and full study of soils background values, including total and available fractions of heavy metal contents should be done. Zanjan province has some great mines and concentrating industries of lead and zinc especially in Angoran, Mahneshan. Unfortunately produced waste materials of these industries spread over the adjacent areas. Investigations showed that accumulation of some heavy metals in vegetables and crops planted in this region had occurred. Therefore, performing some investigations in these polluted areas and assessing pollution rate and heavy metals distribution in arable lands had prime importance. Our goals were: 1 determining the total and available amounts of Cu, Pb, Zn and Cd in the soils of arable lands in polluted areas of Zanjan city, 2 producing the distribution map for the metals mentioned above and 3 calculating pollution indices in the soils. Materials and Methods: The study area was in south west of Zanjan city. For soil sampling, a 1 Km by 1 Km grid defined in ArcGIS software on landuse layer and totally 144 points that placed on agricultural lands, due to our goals, were sampled. For sampling, in a 5m radius around the point we collected some subsamples from depth of 0 - 15 cm, and after mixing the subsamples, finally a 1Kg soil sample prepared and sent to the laboratory. Sampled soils were air dried and were passed through a 2mm sieve. Soils organic matter (OM content and texture were determined by Walkely-Black and Bouyoucos

  15. 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

    Screening of optimal chelating ligands which not only have high capacities to enhance plant uptake of mercury (Hg) from soil but also can decrease bioavailable Hg concentration in soil is necessary to establish a viable chemically-assisted phytoextraction. Therefore, Brassica juncea was exposed to historically Hg-contaminated soil (total Hg, 90 mg kg -1 ) to investigate the efficiency of seven chelating agents [ammonium thiosulphate, sodium thiosulphate, ammonium sulfate, ammonium chloride, sodium nitrate, ethylenediaminetetraacetic acid (EDTA), and sodium sulfite] at enhancing Hg phytoextraction; the leaching of bioavailable Hg caused by these chelating agents was also investigated. The Hg concentration in control (treated with double-distilled water) plant tissues was below 1 mg kg -1 . The remarkably higher Hg concentration was found in plants receiving ammonium thiosulphate and sodium sulfite treatments. The bioaccumulation factors and translocation factors of ammonium thiosulphate and sodium sulfite treatments were significantly higher than those of the other treatments. The more efficient uptake of Hg by plants upon treatment with ammonium thiosulphate and sodium sulfite compared to the other treatments might be explained by the formation of special Hg-thiosulphate complexes that could be preferentially taken up by the roots and transported in plant tissues. The application of sulfite significantly increased bioavailable Hg concentration in soil compared with that in initial soil and control soil, whereas ammonium thiosulphate significantly decreased bioavailable Hg concentration. The apparent decrease of bioavailable Hg in ammonium thiosulphate-treated soil compared with that in sodium sulfite-treated soil might be attributable to the unstable Hg-thiosulphate complexes formed between thiosulphate and Hg; they could react to produce less bioavailable Hg in the soil. The results of this study indicate that ammonium thiosulphate may be an optimal chelating

  16. Degradation of Total Petroleum Hydrocarbon (TPH) in Contaminated Soil Using Bacillus pumilus MVSV3.

    Science.gov (United States)

    Varma, Surendra Sheeba; Lakshmi, Mahalingam Brinda; Rajagopal, Perumalsam; Velan, Manickam

    2017-01-01

     A study on bioremediation of soil contaminated with petroleum sludge was performed using Bacillus pumilus/MVSV3 (Accession number JN089707). In this study, 5 kg of agricultural soil was mixed well with 5% oil sludge and fertilizers containing nitrogen, phosphorus and potassium (N:P:K). The treatment resulted in 97% removal of total petroleum hydrocarbon (TPH) in 122 d in bacteria mixed contaminated soil when compared to 12% removal of TPH in uninoculated contaminated soil. The population of the microorganism remained stable after introduced into the oil environment. The physical and chemical parameters of the soil mixed with sludge showed variation indicating improvement and the pH level decreased during the experiment period. Elemental analysis and Gas Chromatography-Mass Spectroscopy (GC-MS) analysis revealed the bacterial ability to degrade oil sludge components. Growth experiments with Trigonellafoenumgraecum (Fenugreek) showed the applicability of bioremediated soil for the production.

  17. 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.

  18. A new detailed map of total phosphorus stocks in Australian soil.

    Science.gov (United States)

    Viscarra Rossel, Raphael A; Bui, Elisabeth N

    2016-01-15

    Accurate data are needed to effectively monitor environmental condition, and develop sound policies to plan for the future. Globally, current estimates of soil total phosphorus (P) stocks are very uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of total P in Australian soil. Data from several sources were harmonized to produce the most comprehensive inventory of total P in soil of the continent. They were used to produce fine spatial resolution continental maps of total P in six depth layers by combining the bootstrap, a decision tree with piecewise regression on environmental variables and geostatistical modelling of residuals. Values of percent total P were predicted at the nodes of a 3-arcsecond (approximately 90 m) grid and mapped together with their uncertainties. We combined these predictions with those for bulk density and mapped the total soil P stock in the 0-30 cm layer over the whole of Australia. The average amount of P in Australian topsoil is estimated to be 0.98 t ha(-1) with 90% confidence limits of 0.2 and 4.2 t ha(-1). The total stock of P in the 0-30 cm layer of soil for the continent is 0.91 Gt with 90% confidence limits of 0.19 and 3.9 Gt. The estimates are the most reliable approximation of the stock of total P in Australian soil to date. They could help improve ecological models, guide the formulation of policy around food and water security, biodiversity and conservation, inform future sampling for inventory, guide the design of monitoring networks, and provide a benchmark against which to assess the impact of changes in land cover, land use and management and climate on soil P stocks and water quality in Australia. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  19. Separating rhizosphere respiration from total soil respiration in two larch plantations in northeastern China.

    Science.gov (United States)

    Jiang, Lifen; Shi, Fuchen; Li, Bo; Luo, Yiqi; Chen, Jiquan; Chen, Jiakuan

    2005-09-01

    The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 micromol m(-2) s(-1) in winter to 6.0 micromol m(-2) s(-1) in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 micromol m(-2) s(-1) in the old forest and from 0.3 to 4.0 micromol m(-2) s(-1) in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.

  20. Mercury in rice (Oryza sativa L.) and rice-paddy soils under long-term fertilizer and organic amendment.

    Science.gov (United States)

    Tang, Zhenya; Fan, Fangling; Wang, Xinyue; Shi, Xiaojun; Deng, Shiping; Wang, Dingyong

    2018-04-15

    High levels of mercury (Hg), especially methylmercury (MeHg), in rice is of concern due to its potential of entering food chain and the high toxicity to human. The level and form of Hg in rice could be influenced by fertilizers and other soil amendments. Studies were conducted to evaluate the effect of 24 years application of chemical fertilizers and organic amendments on total Hg (THg) and MeHg and their translocation in soil, plants, and rice grain. All treatments led to significantly higher concentrations of MeHg in grain than those from the untreated control. Of nine treatments tested, chemical fertilizers combining with returning rice straw (NPK1+S) led to highest MeHg concentration in grain and soil; while the nitrogen and potassium (NK) treatment led to significantly higher THg in grain. Concentrations of soil MeHg were significantly correlated with THg in soil (r = 0.59 *** ) and MeHg in grain (r = 0.48 *** ). Calcium superphosphate negatively affected plant bioavailability of soil Hg. MeHg concentration in rice was heavily influenced by soil Hg levels. Phosphorus fertilizer was a main source contributing to soil THg, while returning rice straw to the field contributed significantly to MeHg in soil and rice grain. As a result, caution should be exercised in soil treatment or when utilizing Hg-contaminated soils to produce rice for human consumption. Strategic management of rice straw and phosphorus fertilizer could be effective strategies of lowering soil Hg, which would ultimately lower MeHg in rice and the risk of Hg entering food chain. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Determination of total carbonates in soil archaeometry using a new pressure method with temperature compensation

    Science.gov (United States)

    Barouchas, Pantelis; Koulos, Vasilios; Melfos, Vasilios

    2017-04-01

    For the determination of total carbonates in soil archaeometry a new technique was applied using a multi-sensor philosophy, which combines simultaneous measurement of pressure and temperature. This technology is innovative and complies with EN ISO 10693:2013, ASTM D4373-02(2007) and Soil Science Society of America standard test methods for calcium carbonate content in soils and sediments. The total carbonates analysis is based on a pressure method that utilizes the FOGII Digital Soil CalcimeterTM, which is a portable apparatus. The total carbonate content determined by treating a 1.000 g (+/- 0.001 g) dried sample specimens with 6N hydrochloric acid (HCL) reagent grade, in an enclosed reaction vessel. Carbon dioxide gas evolved during the reaction between the acid and carbonate fraction of the specimen, was measured by the resulting pressure generated, taking in account the temperature conditions during the reaction. Prior to analysis the procedure was validated with Sand/Soil mixtures from BIPEA proficiency testing program with soils of different origins. For applying this new method in archaeometry a total number of ten samples were used from various rocks which are related with cultural constructions and implements in Greece. They represent a large range of periods since the Neolithic times, and were selected because there was an uncertainty about their accurate mineralogical composition especially regarding the presence of carbonate minerals. The results were compared to the results from ELTRA CS580 inorganic carbon analyzer using an infrared cell. The determination of total carbonates for 10 samples from different ancient sites indicated a very good correlation (R2 >0.97) between the pressure method with temperature compensation and the infrared method. The proposed method is quickly and accurate in archaeometry and can replace easily other techniques for total carbonates testing. The FOGII Digital Soil CalcimeterTM is portable and easily can be carried for

  2. Laser ablation-laser induced breakdown spectroscopy for the measurement of total elemental concentration in soils.

    Science.gov (United States)

    Pareja, Jhon; López, Sebastian; Jaramillo, Daniel; Hahn, David W; Molina, Alejandro

    2013-04-10

    The performances of traditional laser-induced breakdown spectroscopy (LIBS) and laser ablation-LIBS (LA-LIBS) were compared by quantifying the total elemental concentration of potassium in highly heterogeneous solid samples, namely soils. Calibration curves for a set of fifteen samples with a wide range of potassium concentrations were generated. The LA-LIBS approach produced a superior linear response different than the traditional LIBS scheme. The analytical response of LA-LIBS was tested with a large set of different soil samples for the quantification of the total concentration of Fe, Mn, Mg, Ca, Na, and K. Results showed an acceptable linear response for Ca, Fe, Mg, and K while poor signal responses were found for Na and Mn. Signs of remaining matrix effects for the LA-LIBS approach in the case of soil analysis were found and discussed. Finally, some improvements and possibilities for future studies toward quantitative soil analysis with the LA-LIBS technique are suggested.

  3. Mapping soil total nitrogen of cultivated land at county scale by using hyperspectral image

    Science.gov (United States)

    Gu, Xiaohe; Zhang, Li Yan; Shu, Meiyan; Yang, Guijun

    2018-02-01

    Monitoring total nitrogen content (TNC) in the soil of cultivated land quantitively and mastering its spatial distribution are helpful for crop growing, soil fertility adjustment and sustainable development of agriculture. The study aimed to develop a universal method to map total nitrogen content in soil of cultivated land by HSI image at county scale. Several mathematical transformations were used to improve the expression ability of HSI image. The correlations between soil TNC and the reflectivity and its mathematical transformations were analyzed. Then the susceptible bands and its transformations were screened to develop the optimizing model of map soil TNC in the Anping County based on the method of multiple linear regression. Results showed that the bands of 14th, 16th, 19th, 37th and 60th with different mathematical transformations were screened as susceptible bands. Differential transformation was helpful for reducing the noise interference to the diagnosis ability of the target spectrum. The determination coefficient of the first order differential of logarithmic transformation was biggest (0.505), while the RMSE was lowest. The study confirmed the first order differential of logarithm transformation as the optimal inversion model for soil TNC, which was used to map soil TNC of cultivated land in the study area.

  4. Analysis of total iodine in soils of some agro-ecological zones of Ghana

    International Nuclear Information System (INIS)

    Kwakye, P.K.; Osei-Agyeman, K.; Frimpong, K.A.; Adams, A.B.; Okae-Anti, D.

    2004-10-01

    Iodine is beneficial in human nutrition and to a lesser extent in plant nutrition. Availability of this element in the soil is thought to be via ocean-atmosphere precipitation, iodine minerals and redistribution by vegetation, but very little is known about levels of iodine in Ghanaian soils. We analyzed for the content of total iodine alongside pH, organic carbon, total nitrogen, cation exchange capacity, sand, silt and clay in top soils of selected agro-ecological zones. These soils occur at various locations spanning from the coastline to the far interior. Variations in nutrient elements were attributed to diverse parent materials from which these soils originated and the complex interactions of organic matter, type of clay, acidity-alkalinity and leaching processes. The soils recorded low total iodine content of 0.08 - 3.92 μg g - 1. There was a decreasing trend of iodine from the coastal zone inwards in the order of 1.85, 0.84 and μg g - 1 for the coastal savanna, semi-deciduous rainforest and Guinea savanna agro-ecological zones respectively. Iodine very weakly negatively correlated with C and N and showed a moderate positive correlation with clay content and moderate negative correlations with pH and sand content. (author)

  5. Assessment of soil pollution based on total petroleum hydrocarbons and individual oil substances.

    Science.gov (United States)

    Pinedo, J; Ibáñez, R; Lijzen, J P A; Irabien, Á

    2013-11-30

    Different oil products like gasoline, diesel or heavy oils can cause soil contamination. The assessment of soils exposed to oil products can be conducted through the comparison between a measured concentration and an intervention value (IV). Several national policies include the IV based on the so called total petroleum hydrocarbons (TPH) measure. However, the TPH assessment does not indicate the individual substances that may produce contamination. The soil quality assessment can be improved by including common hazardous compounds as polycyclic aromatic hydrocarbons (PAHs) and aromatic volatile hydrocarbons like benzene, toluene, ethylbenzene and xylenes (BTEX). This study, focused on 62 samples collected from different sites throughout The Netherlands, evaluates TPH, PAH and BTEX concentrations in soils. Several indices of pollution are defined for the assessment of individual variables (TPH, PAH, B, T, E, and X) and multivariables (MV, BTEX), allowing us to group the pollutants and simplify the methodology. TPH and PAH concentrations above the IV are mainly found in medium and heavy oil products such as diesel and heavy oil. On the other hand, unacceptable BTEX concentrations are reached in soils contaminated with gasoline and kerosene. The TPH assessment suggests the need for further action to include lighter products. The application of multivariable indices allows us to include these products in the soil quality assessment without changing the IV for TPH. This work provides useful information about the soil quality assessment methodology of oil products in soils, focussing the analysis into the substances that mainly cause the risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Arsenic and mercury in the soils of an industrial city in the Donets Basin, Ukraine

    Science.gov (United States)

    Conko, Kathryn M.; Landa, Edward R.; Kolker, Allan; Kozlov, Kostiantyn; Gibb, Herman J.; Centeno, Jose; Panov, Boris S.; Panov, Yuri B.

    2013-01-01

    Soil and house dust collected in and around Hg mines and a processing facility in Horlivka, a mid-sized city in the Donets Basin of southeastern Ukraine, have elevated As and Hg levels. Surface soils collected at a former Hg-processing facility had up to 1300 mg kg−1 As and 8800 mg kg−1 Hg; 1M HCl extractions showed 74–93% of the total As, and 1–13% of the total Hg to be solubilized, suggesting differential environmental mobility between these elements. In general, lower extractability of As and Hg was seen in soil samples up to 12 km from the Hg-processing facility, and the extractable (1M HCl, synthetic precipitation, deionized water) fractions of As are greater than those for Hg, indicating that Hg is present in a more resistant form than As. The means (standard deviation) of total As and Hg in grab samples collected from playgrounds and public spaces within 12 km of the industrial facility were 64 (±38) mg kg−1 As and 12 (±9.4) mg kg−1 Hg; all concentrations are elevated compared to regional soils. The mean concentrations of As and Hg in dust from homes in Horlivka were 5–15 times higher than dust from homes in a control city. Estimates of possible exposure to As and Hg through inadvertent soil ingestion are provided.

  7. Environmental quality assessment of reservoirs impacted by Hg from chlor-alkali technologies: case study of a recovery.

    Science.gov (United States)

    Le Faucheur, Séverine; Vasiliu, Dan; Catianis, Irina; Zazu, Mariana; Dranguet, Perrine; Beauvais-Flück, Rebecca; Loizeau, Jean-Luc; Cosio, Claudia; Ungureanu, Costin; Ungureanu, Viorel Gheorghe; Slaveykova, Vera I

    2016-11-01

    Mercury (Hg) pollution legacy of chlor-alkali plants will be an important issue in the next decades with the planned phase out of Hg-based electrodes by 2025 within the Minamata convention. In such a context, the present study aimed to examine the extent of Hg contamination in the reservoirs surrounding the Oltchim plant and to evaluate the possible improvement of the environmental quality since the closure of its chlor-alkali unit. This plant is the largest chlor-alkali plant in Romania, which partly switched to Hg-free technology in 1999 and definitely stopped the use of Hg electrolysis in May 2012. Total Hg (THg) and methylmercury (CH 3 Hg) concentrations were found to decrease in the surface waters and sediments of the reservoirs receiving the effluents of the chlor-alkali platform since the closure of Hg units. Hence, calculated risk quotients (RQ) indicated no adverse effect of Hg for aquatic organisms from the ambient water exposure. RQ of Hg in sediments were mostly all higher than 1, showing important risks for benthic organisms. However, ecotoxicity testing of water and sediments suggest possible impact of other contaminants and their mixtures. Hg hotspots were found in soils around the platform with RQ values much higher than 1. Finally, THg and CH 3 Hg concentrations in fish were below the food safety limit set by the WHO, which contrasts with previous measurements made in 2007 revealing that 92 % of the studied fish were of high risk of consumption. Discontinuing the use of Hg electrodes greatly improved the surrounding environment of chlor-alkali plants within the following years and led to the decrease environmental exposure to Hg through fish consumption. However, sediment and soil still remained highly contaminated and problematic for the river reservoir management. The results of this ecological risk assessment study have important implications for the evaluation of the benefits as well as limits of the Minamata Convention implementation.

  8. Combining mid infrared and total X-ray fluorescence spectroscopy for prediction of soil properties

    Science.gov (United States)

    Towett, Erick; Shepherd, Keith; Sila, Andrew; Aynekulu, Ermias; Cadisch, Georg

    2015-04-01

    Mid-infrared diffuse reflectance spectroscopy (MIR) can predict many soil properties but extractable nutrients are often predicted poorly. We evaluated the potential of MIR and total elemental analysis using total X-ray fluorescence spectroscopy (TXRF), both individually and combined, to predict results of conventional soil tests. Total multi-elemental analysis provides a fingerprint of soil mineralogy and could predict some soil properties and help improve MIR predictions. A set of 700 georeferenced soil samples associated with the Africa Soil Information Service (AfSIS) (www.africasoils.net) from 44 stratified randomly-located 100-km2 sentinel sites distributed across sub-Saharan Africa were analysed for physico-chemical composition using conventional reference methods, and compared to MIR and TXRF spectra using the Random Forests regression algorithm and an internal out-of-bag validation. MIR spectra resulted in good prediction models (R2 >0.80) for organic C and total N, Mehlich-3 Ca and Al, and pH. To test the combined spectroscopic approach, TXRF element concentration data was included as a property predictor along with the first derivative of MIR spectral data using the RF algorithm. Including TXRF did not improve prediction of these properties. TXRF was poorer (R2 0.86) as these elements are not directly determined with TXRF, however the variance explained is still quite high and may be attributable to TXRF signatures relating to mineralogy correlated with protection of soil organic matter. TXRF model for Mehlich-3 Al had excellent prediction capability explaining 81% of the observed variation in extractable Al content and was comparable to that of MIR (R2 = 0.86). However, models for pH and Mehlich-3 exchangeable Ca exhibited R2 values of 0.74 and 0.79 respectively and thus had moderate predictive accuracy, compared to MIR alone with R2 values of 0.82 and 0.84 respectively. Both MIR and TXRF methods predicted soil properties that relate to nutrient

  9. Proportion of root-derived acid phosphomonoesterase in total soil acid phosphomonoesterase in different forests

    Directory of Open Access Journals (Sweden)

    Ladislav Holík

    2011-01-01

    Full Text Available Enzyme acid phosphomonoesterase (APM plays an important role in phosphorus mineralization in different type of terrestrial ecosystems. This enzyme is of great agronomic significance because it hydrolyses organic phosphorus to different forms of inorganic phosphorus which are assimilable by plants. APM may also indicate changes in the quantity and quality of phosphorylated substrates in soil and is a good indicator of its biological state as well as presence of pollutants. APM may be produced by plant roots and soil microorganisms and both of these sources may play different role in phosphorus mineralization in different ecosystems. The aim of this work was determine acid phosphomonoesterase (APM activity location in soil of different forest ecosystems. The APM activity location determination was performed on the basis of root-derived and soil-derived APM and expression of proportion of those root-derived in total soil APM up to 13 cm depth. The results of this preliminary study showed that root-derived APM formed 21–34 % of total soil APM in pine and oak forest.

  10. Evaluation of total petroleum hydrocarbons (TPH in urban soil from Maicao, Colombia

    Directory of Open Access Journals (Sweden)

    Martha L. Castellanos

    2015-09-01

    Full Text Available The presence of total petroleum hydrocarbons (TPH and their effects on soil properties in urban area of Maicao, Colombia, was evaluated. 18 sites were selected: nine contaminated and nine non-contaminated and two depths (0-30 cm and 30-60 cm were evaluated. The medium TPH fraction (Soxhlet reflux method, EPA 3540C and heavy TPH fraction (Soxhlet reflux method, EPA 3550C were extracted. TPH were identified by gas chromatography with flame ionization detector (GC-FID. Soil parameters related potential adsorption were determined: pH, electrical conductivity (EC, organic carbon (OC, cation exchange capacity (CEC, texture; soil moisture retention, aggregate stability. High contents of TPH was found in all fractions. No significant changes were found for texture and (EC. There was an increase in the content of OC (500%, soil aggregation and aggregate stability (200%; slight decrease pH, CEC and soil moisture retention (23.5% soil surface. These results show the vulnerability of the urban soils to the TPH contamination and exposure of the human population to these contaminants.

  11. Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils

    Science.gov (United States)

    Relationships between total soil or bioaccessible lead (Pb), measured using an in vitro bioaccessibility assay, and children’s blood lead levels (BLL) were investigated in an urban neighborhood in Philadelphia, Pennsylvania, USA, with a history of soil Pb contamination....

  12. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    Science.gov (United States)

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. [Accumulation of soil organic carbon and total nitrogen in Pinus yunnanensis forests at different age stages].

    Science.gov (United States)

    Miao, Juan; Zhou, Chuan-Yan; Li, Shi-Jie; Yan, Jun-Hua

    2014-03-01

    Taking three Pinus yunnanensis forests at different ages (19, 28 and 45 a) in Panxian County of Guizhou Province as test objects, we investigated vertical distributions and accumulation rates of soil organic carbon (SOC) and total nitrogen (TN), as well as their relationships with soil bulk density. For the three forests at different age stages, SOC and TN changed consistently along the soil profile, declining with the soil depth. Both SOC and TN storage increased with the forest age. The SOC and TN storage amounts were 96.24, 121.65 and 148.13 t x hm(-2), and 10.76, 12.96 and 13.08 t x hm(-2) for the forest stands with 19 a, 28 a and 45 a, respectively. SOC had a significant positive correlation with soil TN, while both of them had a significant negative relationship with the soil bulk density. The accumulation rates of both SOC and TN storage at different growth periods were different, and the rate in the period from age 19 to 28 was higher than in the period from age 28 to 45.

  14. 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 ...

  15. Population dynamics of active and total ciliate populations in arable soil amended with wheat

    DEFF Research Database (Denmark)

    Ekelund, F.; Frederiksen, Helle B.; Ronn, R.

    2002-01-01

    of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil...... microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable...

  16. Relative contributions of wind and water erosion to total soil loss and its effect on soil properties in sloping croplands of the Chinese Loess Plateau.

    Science.gov (United States)

    Tuo, Dengfeng; Xu, Mingxiang; Gao, Guangyao

    2018-08-15

    Wind and water erosion are two dominant types of erosion that lead to soil and nutrient losses. Wind and water erosion may occur simultaneously to varying extents in semi-arid regions. The contributions of wind and water erosion to total erosion and their effects on soil quality, however, remains elusive. We used cesium-137 ( 137 Cs) inventories to estimate the total soil erosion and used the Revised Universal Soil Loss Equation (RUSLE) to quantify water erosion in sloping croplands. Wind erosion was estimated from the subtraction of the two. We also used 137 Cs inventories to calculate total soil erosion and validate the relationships of the soil quality and erosion at different slope aspects and positions. The results showed that wind erosion (1460tkm -2 a -1 ) on northwest-facing slope was responsible for approximately 39.7% of the total soil loss, and water erosion (2216tkm -2 a -1 ) accounted for approximately 60.3%. The erosion rates were 58.8% higher on northwest- than on southeast-facing slopes. Northwest-facing slopes had lower soil organic carbon, total nitrogen, clay, and silt contents than southeast-facing slopes, and thus, the 137 Cs inventories were lower, and the total soil erosions were higher on the northwest-facing slopes. The variations in soil physicochemical properties were related to total soil erosion. The lowest 137 Cs inventories and nutrient contents were recorded at the upper positions on the northwest-facing slopes due to the successive occurrence of more severe wind and water erosion at the same site. The results indicated that wind and water could accelerate the spatial variability of erosion rate and soil properties and cause serious decreases in the nutrient contents in sloping fields. Our research could help researchers develop soil strategies to reduce soil erosion according to the dominant erosion type when it occurs in a hilly agricultural area. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. 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)

  18. Soil

    International Nuclear Information System (INIS)

    Freudenschuss, A.; Huber, S.; Riss, A.; Schwarz, S.; Tulipan, M.

    2002-01-01

    Environmental soil surveys in each province of Austria have been performed, soils of about 5,000 sites were described and analyzed for nutrients and pollutants, the majority of these data are recorded in the soil information system of Austria (BORIS) soil database, http://www.ubavie.gv.at/umweltsituation/boden/boris), which also contains a soil map of Austria, data from 30 specific investigations mainly in areas with industry and results from the Austria - wide cesium investigation. With respect to the environmental state of soils a short discussion is given, including two geographical charts, one showing which sites have soil data (2001) and the other the cadmium distribution in top soils according land use (forest, grassland, arable land, others). Information related to the soil erosion, Corine land cover (Europe-wide land cover database), evaluation of pollutants in soils (reference values of As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Se, Pb, Tl, Va, Zn, AOX, PAH, PCB, PCDD/pcdf, dioxin), and relevant Austrian and European standards and regulations is provided. Figs. 2, Tables 4. (nevyjel)

  19. Soil, vegetation and total organic carbon stock development in self-restoring abandoned vineyards

    Science.gov (United States)

    József Novák, Tibor; Incze, József; Spohn, Marie; Giani, Luise

    2016-04-01

    Abandoned vineyard's soil and vegetation development was studied on Tokaj Nagy-Hill, which is one of the traditional wine-producing regions of Hungary, it is declared as UNESCO World Heritage site as cultural landscape. Spatial distribution and pattern of vineyards were changing during the last several hundreds of years, therefore significant part of abandoned vineyards were subjected to long-term spontaneous secondary succession of vegetation and self-restoration of soils in absence of later cultivation. Two chronosequences of spontaneously regenerating vineyard abandonments, one on south (S-sequence) and one on southwest (SW-sequence) slope with differing times since their abandonment (193, 142, 101, 63, 39 and 14 years), were compiled and studied. The S-sequence was 25-35% sloped and strongly eroded, and the SW-sequence was 17-25% sloped and moderately eroded. The sites were investigated in respect of vegetation characteristics, soil physico-chemical characteristics, total organic carbon stocks (TOC stocks), accumulation rates of total organic carbon (TOC accumulation rates), and soil profiles, which were classified according to the World Reference Base (WRB) 2014. Vegetation development resulted in shrub-grassland mosaics, supplemented frequently by protected forb species and forest development at the earliest abandonment in S-sequence, and predominantly to forest vegetation in SW-sequence, where trees were only absent at the 63 and 14 years old abandonment sites. In all sites soils on level of reference groups according to WRB were classified, and Cambisols, Regosols, Calcisols, Leptosols, Chernozems and Phaeozems were found. Soils of the S-sequence show shallow remnants of loess cover with colluvic and redeposited soil materials containing 15-65% skeletal volcanic rock of weathering products coated by secondary calcium carbonates. The SW-sequence profiles are developed on deep loess or loess derivatives. The calcium-carbonate content was higher in profiles of

  20. Differential sensitivity of total and active soil microbial communities to drought and forest management.

    Science.gov (United States)

    Bastida, Felipe; Torres, Irene F; Andrés-Abellán, Manuela; Baldrian, Petr; López-Mondéjar, Rubén; Větrovský, Tomáš; Richnow, Hans H; Starke, Robert; Ondoño, Sara; García, Carlos; López-Serrano, Francisco R; Jehmlich, Nico

    2017-10-01

    Climate change will affect semiarid ecosystems through severe droughts that increase the competition for resources in plant and microbial communities. In these habitats, adaptations to climate change may consist of thinning-that reduces competition for resources through a decrease in tree density and the promotion of plant survival. We deciphered the functional and phylogenetic responses of the microbial community to 6 years of drought induced by rainfall exclusion and how forest management affects its resistance to drought, in a semiarid forest ecosystem dominated by Pinus halepensis Mill. A multiOMIC approach was applied to reveal novel, community-based strategies in the face of climate change. The diversity and the composition of the total and active soil microbiome were evaluated by 16S rRNA gene (bacteria) and ITS (fungal) sequencing, and by metaproteomics. The microbial biomass was analyzed by phospholipid fatty acids (PLFAs), and the microbially mediated ecosystem multifunctionality was studied by the integration of soil enzyme activities related to the cycles of C, N, and P. The microbial biomass and ecosystem multifunctionality decreased in drought-plots, as a consequence of the lower soil moisture and poorer plant development, but this decrease was more notable in unthinned plots. The structure and diversity of the total bacterial community was unaffected by drought at phylum and order level, but did so at genus level, and was influenced by seasonality. However, the total fungal community and the active microbial community were more sensitive to drought and were related to ecosystem multifunctionality. Thinning in plots without drought increased the active diversity while the total diversity was not affected. Thinning promoted the resistance of ecosystem multifunctionality to drought through changes in the active microbial community. The integration of total and active microbiome analyses avoids misinterpretations of the links between the soil microbial

  1. ORGANIC CARBON AND TOTAL NITROGEN IN THE DENSIMETRIC FRACTIONS OF ORGANIC MATTER UNDER DIFFERENT SOIL MANAGEMEN

    Directory of Open Access Journals (Sweden)

    MARCELO RIBEIRO VILELA PRADO

    2016-01-01

    Full Text Available The evaluation of land use and management by the measurement of soil organic matter and its fractions has gained attention since it helps in the understanding of the dynamics of their contribution to soil productivity, especially in tropical environments. This study was conducted in the municipality of Colorado do Oeste, state of Rondônia, Brazil and its aim was to determinethe quantity of organic carbon and total nitrogen in the light and heavy fractions of organic matter in the surface layers of a typic hapludalf under different land use systems: Native Forest: open evergreen forest, reference environment; Agroforestry System 1: teak (Tectona grandis LF and kudzu (Pueraria montana; Agroforestry System 2: coffee (Coffea canephora, marandu palisade grass (Brachiaria brizantha cv. Marandu, “pinho cuiabano” (Parkia multijuga, teak and kudzu.; Agroforestry System 3: teak and cocoa (Theobroma cacao; Silvopasture System: teak, cocoa and marandu palisade grass; and Extensive Grazing System: marandu palisade grass. The experimental design was a randomized block in split-split plots (use systems versus soil layers of 0-0.05 and 0.05-0.10 m with three replications. The results showed that relative to Native Forest, the Agroforestry System 2 had equal- and greater amounts of organic carbon and total nitrogen respectively (light and heavy fractions in the soil organic matter, with the light fraction being responsible for storage of approximately 45% and 70% of the organic carbon and total nitrogen, respectively. Therefore, the light densimetric fraction proved to be useful in the early identification of the general decline of the soil organic matter in the land use systems evaluated.

  2. Thermal soil desorption for total petroleum hydrocarbon testing on gas chromatographs

    International Nuclear Information System (INIS)

    Mott, J.

    1995-01-01

    Testing for total petroleum hydrocarbons (TPH) is one of the most common analytical tests today. A recent development in chromatography incorporates Thermal Soil Desorption technology to enable analyses of unprepared soil samples for volatiles such as BTEX components and semi-volatiles such as diesel, PCBs, PAHs and pesticides in the same chromatogram, while in the field. A gas chromatograph is the preferred method for determining TPH because the column in a GC separates the individual hydrocarbons compounds such as benzene and toluene from each other and measures each individually. A GC analysis will determine not only the total amount of hydrocarbon, but also whether it is gasoline, diesel or another compound. TPH analysis with a GC is typically conducted with a Flame Ionization Detector (FID). Extensive field and laboratory testing has shown that incorporation of a Thermal Soil Desorber offers many benefits over traditional analytical testing methods such as Headspace, Solvent Extraction, and Purge and Trap. This paper presents the process of implementing Thermal Soil Desorption in gas chromatography, including procedures for, and advantages of faster testing and analysis times, concurrent volatile and semi-volatile analysis, minimized sample manipulation, single gas (H 2 ) operation, and detection to the part-per billion levels

  3. 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’

  4. Vertical distribution of mercury and MeHg in Nandagang and Beidagang wetlands: Influence of microtopography

    Science.gov (United States)

    Liu, Ruhai; Zhang, Yanyan; Wang, Yan; Zhao, Jin; Shan, Huayao

    2018-02-01

    Wetlands often show different small-scale topography, such as riffle, habitat island, deep water, shallow water zone and dry zone. Core soils in different micro topographical landforms of Nandagang and Beidagang wetlands in North China were sampled for THg and MeHg to analyze the influence of microtopography. Results showed that THg content in surface soil (pollution in past. High THg content in undisturbed natural wetland soil implied accumulation of mercury. Harvest of plant, drained water decreased the accumulation of mercury in wetlands. Water level caused by microtopography affected the production of MeHg. Depth of the highest MeHg content decreased from N1, N2, N6, N3 to N4 following the increase of water level. Plant type and coverage also affected the vertical distribution of MeHg. More detailed profiles of MeHg, organic matter and total phosphorus in different sites show strong differences in soil chemistry, suggesting a complex interplay among hydrology, biogeochemistry and microtopography.

  5. Effect of soil contamination due to wastewater irrigation on total cesium as determined by destructive and nondestructive analytical techniques in some soils of egypt

    International Nuclear Information System (INIS)

    Abdel-Sabour, M.F.; Abdel-Lattif, A.

    2005-01-01

    Fifteen soil samples were chosen from different locations to represent different soils irrigated with different sources of contaminated wastewater (sewage and industrial effluent). Sequential extraction experiment was carried out to determine different forms of Cs in soils. Moreover, Soil samples were analyzed for total Cs using two analytical methods i.e. destructive wet digestion technique (Atomic Absorption Spectrometry, AAS or by summation of all sequential extracted fractions, SUM) and non-destructive technique (Neutron Activation Analysis, NAA). The aim of this study was to evaluate soil total Cs-forms (especially, bio-available fraction) as affected by soil pollution. Cesium was mostly concentrated in the residual fraction, and its values ranged from 57.4% to 82.9 % of total Cs in sandy soils and from 31.5% to 64.5 % of total Cs in tested clayey soil. Then organically bound Cs- fraction followed by Cs-occluded in Fe-Mn fraction, carbonate, exchangeable and water soluble fractions. Results suggested that, Cs level is affected by soil organic matter content, Fe-Mn oxides and clay content. The mobile Cs fraction (the sum of soluble and exchangeable fractions) ranged from 2% up to 9.9 % of total Cs in sandy soils. However, a higher value (9.82% to 15.31 %) could be observed in case of the tested clayey soils. Soils D and E were more contaminated than other tested soils. Data show obviously, that soil contaminated due to the irrigation with either sewage effluent or industrial wastewater has resulted in a drastic increase in both metal-organic and occluded in Fe and Mn oxide fractions followed by the carbonate fraction

  6. Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe.

    Science.gov (United States)

    Cutillas-Barreiro, Laura; Pérez-Rodríguez, Paula; Gómez-Armesto, Antía; Fernández-Sanjurjo, María José; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino; Arias-Estévez, Manuel; Nóvoa-Muñoz, Juan Carlos

    2016-08-15

    We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10-144µg kg(-1), reaching up to 41 and 145mgkg(-1) for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes

    Directory of Open Access Journals (Sweden)

    M. Bahn

    2010-07-01

    Full Text Available Soil respiration (SR constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. However, there still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 80 site-years for 57 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SRMAT, irrespective of the type of ecosystem and biome. This is theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q10. We further show that for seasonally dry sites where annual precipitation (P is lower than potential evapotranspiration (PET, annual SR can be predicted from wet season SRMAT corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SRMAT for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle.

  8. Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela.

    Science.gov (United States)

    Santos-Francés, F; García-Sánchez, A; Alonso-Rojo, P; Contreras, F; Adams, M

    2011-04-01

    An extensive and remote gold mining region located in the East of Venezuela has been studied with the aim of assessing the distribution and mobility of mercury in soil and the level of Hg pollution at artisanal gold mining sites. To do so, soils and pond sediments were sampled at sites not subject to anthropological influence, as well as in areas affected by gold mining activities. Total Hg in regionally distributed soils ranged between 0.02 mg kg(-1) and 0.40 mg kg(-1), with a median value of 0.11 mg kg(-1), which is slightly higher than soil Hg worldwide, possibly indicating long-term atmospheric input or more recent local atmospheric input, in addition to minor lithogenic sources. A reference Hg concentration of 0.33 mg kg(-1) is proposed for the detection of mining affected soils in this region. Critical total Hg concentrations were found in the surrounding soils of pollutant sources, such as milling-amalgamation sites, where soil Hg contents ranged from 0.16 mg kg(-1) to 542 mg kg(-1) with an average of 26.89 mg kg(-1), which also showed high levels of elemental Hg, but quite low soluble+exchangeable Hg fraction (0.02-4.90 mg kg(-1)), suggesting low Hg soil mobility and bioavailability, as confirmed by soil column leaching tests. The vertical distribution of Hg through the soil profiles, as well as variations in soil Hg contents with distance from the pollution source, and Hg in pond mining sediments were also analysed. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. High-throughput sequencing of nematode communities from total soil DNA extractions

    DEFF Research Database (Denmark)

    Sapkota, Rumakanta; Nicolaisen, Mogens

    2015-01-01

    nematodes without the need for enrichment was developed. Using this strategy on DNA templates from a set of 22 agricultural soils, we obtained 64.4% sequences of nematode origin in total, whereas the remaining sequences were almost entirely from other metazoans. The nematode sequences were derived from...... in previous sequence-based studies are not nematode specific but also amplify other groups of organisms such as fungi and plantae, and thus require a nematode enrichment step that may introduce biases. Results: In this study an amplification strategy which selectively amplifies a fragment of the SSU from...... a broad taxonomic range and most sequences were from nematode taxa that have previously been found to be abundant in soil such as Tylenchida, Rhabditida, Dorylaimida, Triplonchida and Araeolaimida. Conclusions: Our amplification and sequencing strategy for assessing nematode diversity was able to collect...

  10. 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

  11. Organic horizon and mineral soil mercury along three clear-cut forest chronosequences across the northeastern USA.

    Science.gov (United States)

    Richardson, Justin B; Petrenko, Chelsea L; Friedland, Andrew J

    2017-12-01

    Mercury (Hg) is a globally distributed pollutant trace metal that has been increasing in terrestrial environments due to rising anthropogenic emissions. Vegetation plays an important role in Hg sequestration in forested environments, but increasing tree removal for biofuels and wood products may affect this process. The long-term effect of clear-cutting on forest soil Hg remains uncertain, since most studies are limited to measuring changes for event. The chronosequence approach, which substitutes space for time using forest stands of different ages since clear-cutting, allows for investigation of processes occurring over decades to centuries. Here, we utilized three clear-cut forest soil chronosequences across the northeastern USA to understand Hg accumulation and retention over several decades. Total Hg concentrations and pools were quantified for five soil depth increments along three chronosequences. Our results showed Hg concentrations and pools decreased in the initial 20 years following clear-cutting. Mineral soil Hg pools decreased 21-53% (7-14 mg m -2 ) between 1-5-year-old stands and 15-25-year-old stands but mineral soil Hg pools recovered in 55-140-year-old stands to similar values as measured in 1-5-year-old stands. Our study is one of the first to demonstrate a decrease and recovery in Hg pool size. These changes in Hg did not correspond with changes in bulk density, soil C, or pH. We utilized a simple two-box model to determine how different Hg fluxes affected organic and mineral soil horizon Hg pools. Our simple model suggests that changes in litterfall and volatilization rates could have caused the observed changes in organic horizon Hg pools. However, only increases in leaching could reproduce observed decreases to mineral soil Hg pools. Further studies are needed to determine the mechanism of Hg loss from forest soils following clear-cutting.

  12. Using 137Cs to quantify the redistribution of soil organic carbon and total N affected by intensive soil erosion in the headwaters of the Yangtze River, China

    International Nuclear Information System (INIS)

    Wei Guoxiao; Wang Yibo; Wang Yanlin

    2008-01-01

    Characteristics of soil organic carbon (SOC) and total nitrogen (total N) are important for determining the overall quality of soils. Studies on spatial and temporal variation in SOC and total N are of great importance because of global environmental concerns. Soil erosion is one of the major processes affecting the redistribution of SOC and total N in the test fields. To characterize the distribution and dynamics of SOC and N in the intensively eroded soil of the headwaters of the Yangtze River, China, we measured profiles of soil organic C, total N stocks, and 137 Cs in a control plot and a treatment plot. The amounts of SOC, 137 Cs of sampling soil profiles increased in the following order, lower>middle>upper portions on the control plot, and the amounts of total N of sampling soil profile increase in the following order: upper>middle>lower on the control plot. Intensive soil erosion resulted in a significant decrease of SOC amounts by 34.9%, 28.3% and 52.6% for 0-30 cm soil layer at upper, middle and lower portions and 137 Cs inventory decreased by 68%, 11% and 85% at upper, middle and lower portions, respectively. On the treatment plot total N decreased by 50.2% and 14.6% at the upper and middle portions and increased by 48.9% at the lower portion. Coefficients of variation (CVs) of SOC decreased by 31%, 37% and 30% in the upper, middle and lower slope portions, respectively. Similar to the variational trend of SOC, CVs of 137 Cs decreased by 19.2%, 0.5% and 36.5%; and total N decreased by 45.7%, 65.1% and 19% in the upper, middle and lower slope portions, respectively. The results showed that 137 Cs, SOC and total N moved on the sloping land almost in the same physical mechanism during the soil erosion procedure, indicating that fallout of 137 Cs could be used directly for quantifying dynamic SOC and total N redistribution as the soil was affected by intensive soil erosion

  13. Using (137)Cs to quantify the redistribution of soil organic carbon and total N affected by intensive soil erosion in the headwaters of the Yangtze River, China.

    Science.gov (United States)

    Guoxiao, Wei; Yibo, Wang; Yan Lin, Wang

    2008-12-01

    Characteristics of soil organic carbon (SOC) and total nitrogen (total N) are important for determining the overall quality of soils. Studies on spatial and temporal variation in SOC and total N are of great importance because of global environmental concerns. Soil erosion is one of the major processes affecting the redistribution of SOC and total N in the test fields. To characterize the distribution and dynamics of SOC and N in the intensively eroded soil of the headwaters of the Yangtze River, China, we measured profiles of soil organic C, total N stocks, and (137)Cs in a control plot and a treatment plot. The amounts of SOC, (137)Cs of sampling soil profiles increased in the following order, lower>middle>upper portions on the control plot, and the amounts of total N of sampling soil profile increase in the following order: upper>middle>lower on the control plot. Intensive soil erosion resulted in a significant decrease of SOC amounts by 34.9%, 28.3% and 52.6% for 0-30cm soil layer at upper, middle and lower portions and (137)Cs inventory decreased by 68%, 11% and 85% at upper, middle and lower portions, respectively. On the treatment plot total N decreased by 50.2% and 14.6% at the upper and middle portions and increased by 48.9% at the lower portion. Coefficients of variation (CVs) of SOC decreased by 31%, 37% and 30% in the upper, middle and lower slope portions, respectively. Similar to the variational trend of SOC, CVs of (137)Cs decreased by 19.2%, 0.5% and 36.5%; and total N decreased by 45.7%, 65.1% and 19% in the upper, middle and lower slope portions, respectively. The results showed that (137)Cs, SOC and total N moved on the sloping land almost in the same physical mechanism during the soil erosion procedure, indicating that fallout of (137)Cs could be used directly for quantifying dynamic SOC and total N redistribution as the soil was affected by intensive soil erosion.

  14. COMPARISON OF DIFFERENT EXTRACTION METHODS REPRESENTING AVAILABLE AND TOTAL CONCENTRATIONS OF Cd, Cu, Fe, Mn and Zn IN SOIL

    Directory of Open Access Journals (Sweden)

    Vladimir Ivezić

    2013-06-01

    Full Text Available Various extraction methods are used to predict plant uptake of trace metals. Most commonly it is total concentration that is used for risk assessment and evaluation of trace metal availability. However, recent studies showed that total concentration is a poor indicator of availability while concentrations in soil solution show good correlation with plant uptake. Present study was conducted on magricultural soils with low levels of trace metals where 45 soil samples were collected from different soil types. The main objective was to compare four different extraction methods and examine how total and reactive (EDTA trace metal concentrations correlate ,with soil solution concentration (in this study determined by water extraction. The samples were analyzed by four extraction methods: strong acid extraction (ultra-pure HNO3 extraction and aqua regia, weak acid extraction by EDTA and the most available fraction, fraction in soil solution, were represented by water extraction (weakest extractant. Five elements were investigated (Cd, Cu, Fe, Mn and Zn. Water extraction significantly correlated with EDTA extraction for Cu, Fe and Mn, while total extraction (HNO3 extraction and aqua regia correlated significantly with water extraction only for Cu. No correlation between water extraction and total extraction confirmed poor role of total concentration as an indicator of availability. EDTA extraction can be used to represent reactive pool of trace metals in soil but it should be also taken with caution when using it to describe available fraction.

  15. 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.)

  16. Determination of total cyanide in soil by isotope dilution GC/MS following pentafluorobenzyl derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, Beatrice, E-mail: beatrice.campanella@pi.iccom.cnr.it [Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via Moruzzi 13, 56124 Pisa (Italy); Consiglio Nazionale delle Ricerche (CNR), Istituto di Chimica dei Composti Organometallici, UOS di Pisa, via Moruzzi 1, 56124 Pisa (Italy); Biancalana, Lorenzo [Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via Moruzzi 13, 56124 Pisa (Italy); D' Ulivo, Lucia [National Research Council of Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Onor, Massimo; Bramanti, Emilia [Consiglio Nazionale delle Ricerche (CNR), Istituto di Chimica dei Composti Organometallici, UOS di Pisa, via Moruzzi 1, 56124 Pisa (Italy); Mester, Zoltan; Pagliano, Enea [National Research Council of Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada)

    2017-04-08

    The high toxicity of cyanide, along with its widespread industrial use, has fuelled interest in the development of analytical methods for its determination in complex matrices. In this study, we propose a novel approach for the measurement of total cyanide in soil samples based on single-step derivatization with pentafluorobenzyl bromide (F{sub 5}Bn−Br) followed by quantitation with gas chromatography mass spectrometry in negative chemical ionization mode. The reaction between CN{sup −} and F{sub 5}Bn−Br resulted in the identification of several derivatives such as F{sub 5}Bn−CN, (F{sub 5}Bn)(F{sub 5}Ph)CH−CN, and (F{sub 5}Bn){sub 2}(F{sub 5}Ph)C−CN. The relative proportion between such compounds was dependent on experimental conditions. When a 100 μL aliquot of an alkaline-aqueous extract was reacted with 700 μL of 1.3% F{sub 5}Bn−Br in acetone, the tri-alkylated derivative was the most abundant. In such conditions a detection limit of 0.5 ng/g of CN{sup −} was attained. Soil samples were initially spiked with an alkaline solution of K{sup 13}C{sup 15}N internal standard and suspended in 7.5% aqueous NaOH. Determination of total cyanide was achieved by digestion of the alkaline extract with H{sub 3}PO{sub 4} to produce HCN which was then trapped in 0.1% NaOH in a sealed double vial system, followed by reaction with F{sub 5}Bn−Br. Isotope dilution calibration was chosen for quantitation, and the validity of the novel method was demonstrated by analysis of soil Certified Reference Materials (CRMs) and by spike recovery tests. - Highlights: • A cost-effective, fast and simple method for determination of total cyanide in soil is presented. • A new micro-distillation strategy was developed overcoming the problems of a conventional distillation. • Negative chemical ionization-mass spectrometer has been exploited to obtain a high sensitivity and specificity. • High accuracy was attained for the analysis of certified reference materials with

  17. Evaluation of automated analysis of 15N and total N in plant material and soil

    DEFF Research Database (Denmark)

    Jensen, E.S.

    1991-01-01

    Simultaneous determination of N-15 and total N using an automated nitrogen analyser interfaced to a continuous-flow isotope ratio mass spectrometer (ANA-MS method) was evaluated. The coefficient of variation (CV) of repeated analyses of homogeneous standards and samples at natural abundance...... was lower than 0.1%. The CV of repeated analyses of N-15-labelled plant material and soil samples varied between 0.3% and 1.1%. The reproducibility of repeated total N analyses using the automated method was comparable to results obtained with a semi-micro Kjeldahl procedure. However, the automated method...... analysis showed that the recovery of inorganic N in the NH3 trap was lower when the N was diffused from water than from 2 M KCl. The results also indicated that different proportions of the NO3- and the NH4+ in aqueous solution were recovered in the trap after combined diffusion. The method is most suited...

  18. Total mercury, methylmercury and selenium in mercury polluted areas in the province Guizhou, China.

    Science.gov (United States)

    Horvat, Milena; Nolde, Natasa; Fajon, Vesna; Jereb, Vesna; Logar, Martina; Lojen, Sonja; Jacimovic, Radojko; Falnoga, Ingrid; Liya, Qu; Faganeli, Jadran; Drobne, Damjana

    2003-03-20

    The province of Guizhou in Southwestern China is currently one of the world's most important mercury production areas. Emissions of mercury from the province to the global atmosphere have been estimated to be approximately 12% of the world total anthropogenic emissions. The main objective of this study was to assess the level of contamination with Hg in two geographical areas of Guizhou province. Mercury pollution in the areas concerned originates from mercury mining and ore processing in the area of Wanshan, while in the area of Quingzhen mercury pollution originates from the chemical industry discharging Hg through wastewaters and emissions to the atmosphere due to coal burning for electricity production. The results of this study confirmed high contamination with Hg in soil, sediments and rice in the Hg mining area in Wanshan. High levels of Hg in soil and rice were also found in the vicinity of the chemical plant in Quingzhen. The concentrations of Hg decreased with distance from the main sources of pollution considerably. The general conclusion is that Hg contamination in Wanshan is geographically more widespread, due to deposition and scavenging of Hg from contaminated air and deposition on land. In Quingzhen Hg contamination of soil is very high close to the chemical plant but the levels reach background concentrations at a distance of several km. Even though the major source of Hg in both areas is inorganic Hg, it was observed that active transformation of inorganic Hg to organic Hg species (MeHg) takes place in water, sediments and soils. The concentration of Hg in rice grains can reach up to 569 microg/kg of total Hg of which 145 microg/kg was in MeHg form. The percentage of Hg as MeHg varied from 5 to 83%. The concentrations of selenium can reach up to 16 mg/kg in soil and up to 1 mg/g in rice. A correlation exists between the concentration of Se in soil and rice, indicating that a portion of Se is bioavailable to plants. No correlation between Hg and Se

  19. Effect Of Soil Contamination Due To Wastewater Irrigation On Total Co As Determined By Neutron Activation And Other Conventional Analytical Techniques In Some Soils Of Egypt

    International Nuclear Information System (INIS)

    Abdel-Sabour, M. F.; Al-Salama, Y. J.

    2004-01-01

    Fifteen soil samples were chosen from different locations (five different locations at north greater Cairo, Egypt) to represent different soils (alluvial and sandy) as well as different sources of contaminated wastewater (sewage and industrial effluent). Using sequential extraction technique (extracting the soil with different solutions, which is designed to separate metal fractions), Co was separated into six operationally defined fractions: water soluble, exchangeable, carbonate bound, Fe-Mn oxides bound, organic bound and residual fractions. Moreover, total-Co in soils as determined by three analytical methods (sum of sequential extracting, Atomic Absorption Spectrometry (AAS) and neutron activation analysis (NAA) techniques) were compared. Cobalt distribution between different extractants shows that the greatest amounts are found in the residual and Occluded in Fe and Mn-Oxides fractions followed by carbonate or organic fractions. In most cases the proportion of all tested Co-forms has increased in contaminated soil layers with higher enrichment in organically bound Co, occluded in Fe and Mn oxides, carbonate exchangeable and soluble fractions. Results indicate that soil properties have a significant role on Co fractions in soil. In the mean time, soil properties are affected by pollution factors such as source of pollution and load of pollution on the studied soil. Data showed that values of total Co determined by NAA method were always higher than the relevant values determined by AAS or those calculated after the sequential extraction method. (Authors)

  20. [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.

  1. 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.

  2. Determination of total and electrolabile copper in agricultural soil by using disposable modified-carbon screen-printed electrodes.

    Science.gov (United States)

    Faucher, Stéphane; Cugnet, Cyril; Authier, Laurent; Lespes, Gaëtane

    2014-02-01

    The objective of the study is to evaluate modified-carbon screen-printed working electrodes (SPE) combined with square wave anodic stripping voltammetry (SWASV) to determine electrolabile and total copper in soils with the perspective to assess the environmental hazard resulting from copper anthropogenic contamination. The voltammetric method was investigated using a mineralized certified reference soil such that it can be assumed that the copper was totally under electrolabile form in the solution of mineralized soil. In optimal conditions, a copper recovery of 97% and a relative standard deviation (RSD) of 9% were found. The limits of detection and quantification for copper were 0.4 and 1.3 μg L(-1), respectively. Finally, the method was applied on soil leachates, which allowed evaluating the cupric transfer from the soil to the leachates and quantifying the electrolabile copper part in leachates.

  3. Measurement of Total Free Iron in Soils by H2S Chemisorption and Comparison with the Citrate Bicarbonate Dithionite Method

    Directory of Open Access Journals (Sweden)

    Shui-Sheng Fan

    2016-01-01

    Full Text Available Free iron is one of the major analytical items for soil basic properties. It is also an important indicator for understanding the genesis of soil, soil classification, and soil distribution behavior. In this study, an alternative analytical method (chemisorption based on thermodynamic knowledge was proposed for measurement of total free iron oxides in soils. Several representative soil samples belonging to alfisols, ultisols, inceptisols, and entisols were collected from Taiwan and tested by the chemisorption, and the estimated total free iron oxides were compared with those measured from the traditional citrate bicarbonate dithionite (CBD method. Experimental results showed that the optimal operating temperature was found to be at 773 K and the carbon monoxide (CO is the best gaseous reagent to promote the formation of FeS. The estimated total free iron oxides for soil samples determined from the chemisorption in the presence of CO were very close to those from the CBD technique. The result of regression indicates that the estimated total free iron is strongly correlated with the CBD-Fe content (R2=0.999 in the presence of CO.

  4. 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

  5. Application of neutron activation analysis to the determination of total mercury and other elements of interest in soil and sediment samples from Serra do Navio and Vila Nova River Basin, Amapa, Brazil

    International Nuclear Information System (INIS)

    Goncalves, Cristina

    1997-01-01

    In this work it is presented a survey on total mercury determination by a radiochemical method in sediment and soil samples from two regions, in the state of Amapa: Serra do Navio (background area) and Vila Nova river basin (gold mining area). The method consisted in leaching of the irradiated samples with acqua regia in a Parr bomb, and heating in microwave oven, for one minute. Then the solvent extraction technique was applied, using bismuth diethyldithiocarbamate (Bi(DDC) 3 ) as extractant agent. The organic phase, containing 197 Hg and 203 Hg radioisotopes, was measured in a gamma spectrometer with hyper pure Ge detector. This method eliminated the interference of the 279.54 keV photopeak of 75 Se on 279.2 keV photopeak of 203 Hg, besides improving counting statistics of both Hg radioisotopes. The elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, Ho, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, Ti, U, V, W, Yb, Zn and Zr were also determined by the instrumental neutron activation analysis. Two irradiation series were carried out to quantify these elements in soil and sediment samples; a short term irradiation allowed to evaluate Mg, Mn, Na, Ti and V levels, and by long term irradiation, the other elements were determined. Precision and accuracy of radiochemical procedure were verified by means of analysis of the reference materials Buffalo River Sediment and Lake Sediment, for sediments and GXR-5, for soils. For the instrumental analysis, the reference materials Buffalo River Sediment, Soil 7, JB-1 and Oyster Tissue were used. The samples were also submitted to X ray diffraction, in Instituto de Geoscience-USP, to observe mercury behaviour with mineralogy. Aluminium concentration was determined by X ray fluorescence method, in the Department of Materials, IPEN/CNEN-SP, making possible enrichment factor calculation so that mercurial contamination in the gold mining area (Vila Nova river basin) could be evaluated. The mercury levels obtained in this

  6. Efeito da temperatura, pH e vestígios de Hg2+ e Pb2+ na acti­vidade de desidrogenases e urease num solo da região de Évora Effect of temperature, pH and Hg2+ and Pb2+ traces in dehydrogenaseand urease activities of a soil from Évora region

    Directory of Open Access Journals (Sweden)

    M. R. Martins

    2010-01-01

    Full Text Available As actividades das enzimas no solo são um importante indicador da sua qualida­de. Neste estudo procedeu-se à caracteri­zação da actividade enzimática de desi­drogenases (EC 1.1.1 e da urease (EC 3.5.1.5 de um solo sob Olea europeae L. da região de Évora. As constantes cinéti­cas Km e Vmáx, foram determinadas usando como substratos o cloreto de p­-iodonitrotetrazolio (INT e a ureia, res­pectivamente. Foi avaliado o efeito nas referidas actividades provocado pelo pH, temperatura e vestígios de Hg2+ e de Pb2+. As actividades máximas obtiveram-se a pH = 8,5 e 40 ºC, com Km= 0,5 mM e Vmáx = 5,4 µmol min-1 g-1, para a activida­de de desidrogenases e a pH = 10 e 37 ºC, com Km = 25,7 mM e Vmáx = 2,0x10-2 µmol min-1 g-1, para a urease. Estas acti­vidades foram inibidas por diferentes concentrações de Hg2+, mas apenas a acti­vidade da urease foi inibida pelo Pb2+. Estes resultados são comparáveis com os referidos na literatura para estes enzimas.Enzyme activities are often used as in­dicator of soil quality. This study reports on dehydrogenase (EC 1.1.1 and urease (EC 3.5.1.5 activities of a soil under Olea europaea L. from Évora region. Kinetic constants Km and Vmax were determined using p-iodonitrotetrazolium chloride (INT and urea, respectively. Effects of pH, temperature and Hg2+ and Pb2+ traces on both activities were determined. Maximal activity was obtained at pH = 8.5 and 40ºC, Km = 0.5 mM and Vmax=5,4µmol min-1 g-1 , for dehydro­genase and at pH = 10 and 37 ºC, Km = 25.7 mM and Vmax = 2.0x10-2 µmol min-1 g-1, for urease. These activities were in­hibited by different concentrations of Hg2+, but only the urease activity was in­hibited by Pb2+. Results of this study are comparable to those reported in the litera­ture for these enzymes.

  7. Total and methyl mercury concentrations and fluxes from small boreal forest catchments in Finland

    International Nuclear Information System (INIS)

    Porvari, Petri; Verta, Matti

    2003-01-01

    Peatlands have higher methyl mercury output than uplands. - Total mercury (TotHg) and methyl mercury (MeHg) concentrations were studied in runoff from eight small (0.02-1.3 km 2 ) boreal forest catchments (mineral soil and peatland) during 1990-1995. Runoff waters were extremely humic (TOC 7-70 mg l -1 ). TotHg concentrations varied between 0.84 and 24 ng l -1 and MeHg between 0.03 and 3.8 ng l -1 . TotHg fluxes from catchments ranged from 0.92 to 1.8 g km -2 a -1 , and MeHg fluxes from 0.03 to 0.33 g km -2 a -1 . TotHg concentrations and output fluxes measured in runoff water from small forest catchments in Finland were comparable with those measured in other boreal regions. By contrast, MeHg concentrations were generally higher. Estimates for MeHg output fluxes in this study were comparable at sites with forests and wetlands in Sweden and North America, but clearly higher than those measured at upland or agricultural sites in other studies. Peatland catchments released more MeHg than pure mineral soil or mineral soil catchments with minor area of peatland

  8. Total belowground carbon flux in subalpine forests is related to leaf area index, soil nitrogen, and tree height

    Science.gov (United States)

    Berryman, Erin Michele; Ryan, Michael G.; Bradford, John B.; Hawbaker, Todd J.; Birdsey, R.

    2016-01-01

    In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynthesis increases yet C partitioning to TBCF decreases in response to high soil fertility. We hypothesized that these causal relationships would result in predictable patterns of TBCF, and partitioning of C to TBCF, with natural variability in leaf area index (LAI), soil nitrogen (N), and tree height in subalpine forests in the Rocky Mountains, USA. Using three consecutive years of soil respiration data collected from 22 0.38-ha locations across three 1-km2 subalpine forested landscapes, we tested three hypotheses: (1) annual soil respiration and TBCF will show a hump-shaped relationship with LAI; (2) variability in TBCF unexplained by LAI will be related to soil nitrogen (N); and (3) partitioning of C to TBCF (relative to woody growth) will decline with increasing soil N and tree height. We found partial support for Hypothesis 1 and full support for Hypotheses 2 and 3. TBCF, but not soil respiration, was explained by LAI and soil N patterns (r2 = 0.49), and the ratio of annual TBCF to TBCF plus aboveground net primary productivity (ANPP) was related to soil N and tree height (r2 = 0.72). Thus, forest C partitioning to TBCF can vary even within the same forest type and region, and approaches that assume a constant fraction of TBCF relative to ANPP may be missing some of this variability. These relationships can aid with estimates of forest soil respiration and TBCF across landscapes, using spatially explicit forest data such as national inventories or remotely sensed data products.

  9. Phylogenetic and Functional Diversity of Total (DNA) and Expressed (RNA) Bacterial Communities in Urban Green Infrastructure Bioswale Soils.

    Science.gov (United States)

    Gill, Aman S; Lee, Angela; McGuire, Krista L

    2017-08-15

    New York City (NYC) is pioneering green infrastructure with the use of bioswales and other engineered soil-based habitats to provide stormwater infiltration and other ecosystem functions. In addition to avoiding the environmental and financial costs of expanding traditional built infrastructure, green infrastructure is thought to generate cobenefits in the form of diverse ecological processes performed by its plant and microbial communities. Yet, although plant communities in these habitats are closely managed, we lack basic knowledge about how engineered ecosystems impact the distribution and functioning of soil bacteria. We sequenced amplicons of the 16S ribosomal subunit, as well as seven genes associated with functional pathways, generated from both total (DNA-based) and expressed (RNA) soil communities in the Bronx, NYC, NY, in order to test whether bioswale soils host characteristic bacterial communities with evidence for enriched microbial functioning, compared to nonengineered soils in park lawns and tree pits. Bioswales had distinct, phylogenetically diverse bacterial communities, including taxa associated with nutrient cycling and metabolism of hydrocarbons and other pollutants. Bioswale soils also had a significantly greater diversity of genes involved in several functional pathways, including carbon fixation ( cbbL-R [ cbbL gene, red-like subunit] and apsA ), nitrogen cycling ( noxZ and amoA ), and contaminant degradation ( bphA ); conversely, no functional genes were significantly more abundant in nonengineered soils. These results provide preliminary evidence that urban land management can shape the diversity and activity of soil communities, with positive consequences for genetic resources underlying valuable ecological functions, including biogeochemical cycling and degradation of common urban pollutants. IMPORTANCE Management of urban soil biodiversity by favoring taxa associated with decontamination or other microbial metabolic processes is a

  10. The activity and community structure of total bacteria and denitrifying bacteria across soil depths and biological gradients in estuary ecosystem.

    Science.gov (United States)

    Lee, Seung-Hoon; Kang, Hojeong

    2016-02-01

    The distribution of soil microorganisms often shows variations along soil depth, and even in the same soil layer, each microbial group has a specific niche. In particular, the estuary soil is intermittently flooded, and the characteristics of the surface soil layer are different from those of other terrestrial soils. We investigated the microbial community structure and activity across soil depths and biological gradients composed of invasive and native plants in the shallow surface layer of an estuary ecosystem by using molecular approaches. Our results showed that the total and denitrifying bacterial community structures of the estuarine wetland soil differed according to the short depth gradient. In growing season, gene copy number of 16S rRNA were 1.52(±0.23) × 10(11), 1.10(±0.06) × 10(11), and 4.33(±0.16) × 10(10) g(-1) soil; nirS were 5.41(±1.25) × 10(8), 4.93(±0.94) × 10(8), and 2.61(±0.28) × 10(8) g(-1) soil; and nirK were 9.67(±2.37) × 10(6), 3.42(±0.55) × 10(6), and 2.12(±0.19) × 10(6) g(-1) soil in 0 cm, 5 cm, and 10 cm depth layer, respectively. The depth-based difference was distinct in the vegetated sample and in the growing season, evidencing the important role of plants in structuring the microbial community. In comparison with other studies, we observed differences in the microbial community and functions even across very short depth gradients. In conclusion, our results suggested that (i) in the estuary ecosystem, the denitrifying bacterial community could maintain its abundance and function within shallow surface soil layers through facultative anaerobiosis, while the total bacterial community would be both quantitatively and qualitatively affected by the soil depth, (ii) the nirS gene community, rather than the nirK one, should be the first candidate used as an indicator of the microbial denitrification process in the estuary system, and (iii) as the microbial community is distributed and plays a certain niche role according to

  11. Is black carbon a better predictor of polycyclic aromatic hydrocarbon distribution in soils than total organic carbon?

    International Nuclear Information System (INIS)

    Agarwal, Tripti; Bucheli, Thomas D.

    2011-01-01

    Black carbon (BC) and total organic carbon (TOC) were quantified in the surface soils of Switzerland (N = 105) and Delhi (N = 36), India, to examine their relationships with contents of polycyclic aromatic hydrocarbons (PAH). BC content in Swiss (background) soils (N = 104) varied from 0.41 to 4.75 mg/g (median: 1.13 mg/g) and constituted 1-9% (median: 3%) of TOC. Indian (urban) soils had similar BC concentrations (0.37-2.05 mg/g, median: 1.19 mg/g), with relatively higher BC/TOC (6-23%, median: 13%). Similar to TOC, BC showed significant positive correlation with lighter PAH, but no correlation with heavier PAH in Swiss soils. In contrast, heavier PAH were significantly correlated only with BC in Delhi soils. It seems that TOC governs the distribution of PAH in organic matter rich background soils, while the proximity to emission sources is reflected by BC-PAH association in urban soils. - Light PAH correlated with TOC in background soils, whereas heavy PAH were associated with BC close to emission sources.

  12. Is the Total Concentration of a Heavy Metal in Soil a Suitable Tool for Assessing the Environmental Risk? Considering the Case of Copper

    Science.gov (United States)

    Fernández-Calviño, David; Pérez-Rodríguez, Paula; Nóvoa-Muñoz, Juan Carlos; Estévez, Manuel Arias

    2017-01-01

    National legislation concerning soil pollution by heavy metals in different countries is mostly based on the total heavy metal concentration levels allowed in different soils. As soil pollution is an issue of worldwide concern, here we develop a laboratory exercise for students in which they must check the suitability of a total metal…

  13. Oil characterisation: assessment of composition, risks, degradation and remediation potential of total petroleum hydrocarbons in soil

    International Nuclear Information System (INIS)

    Lookman, R.; Vanermen, G.; Van De Weghe, H.; Gemoets, J.; Van der Sterren, G.; Alphenaar, A.

    2005-01-01

    Several methods are available for the characterization of petroleum hydrocarbons. The TPHCWG (Total Petroleum Hydrocarbon Criteria Working Group) developed a method based on a silica column separation of aromatics and aliphatics and a GC-FID subdivision into equivalent-carbon fractions (EC) ('TPH-method'). This method was mainly developed for assessing human risks of oil compounds. Within NOBIS (Dutch Research program Biological In-situ Remediation), another method was developed based upon an equilibrium-experiment of the oil-polluted soil with water (column recirculation), which was further developed by TTE ('TTE-method'). This method uses measured water solubilities of individual oil components and GC-retention times yielding a subdivision of the hydrocarbons into compound classes that are relevant for assessing the remediation potential of the specific oil pollution. In this paper we present results of a research project in which we developed a new method, the 'OK-method' that combines these two procedures and allows a complete characterisation of the oil in terms of composition, (human) risks, volatility, solubility, plume behaviour (migration velocities of the soluble components) and aerobic degradation potential. (authors)

  14. Integration into plant biology and soil science has provided insights into the total environment.

    Science.gov (United States)

    Shao, Hongbo; Lu, Haiying; Xu, Gang; Marian, Brestic

    2017-02-01

    The total environment includes 5 closely-linking circles, in which biosphere and lithosphere are the active core. As global population increases and urbanization process accelerates, arable land is gradually decreasing under global climate change and the pressure of various types of environmental pollution. This case is especially for China. Land is the most important resources for human beings' survival. How to increase and manage arable land is the key for sustainable agriculture development. China has extensive marshy land that can be reclamated for the better potential land resources under the pre- condition of protecting the environment, which will be a good way for enlarging globally and managing arable land. Related studies have been conducted in China for the past 30years and now many results with obvious practical efficiency have been obtained. For summarizing these results, salt-soil will be the main target and related contents such as nutrient transport, use types, biodiversity and interactions with plants from molecular biology to ecology will be covered, in which the interactions among biosphere, lithosphere, atmosphere and anthroposphere will be focused on. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Oil characterisation: assessment of composition, risks, degradation and remediation potential of total petroleum hydrocarbons in soil

    Energy Technology Data Exchange (ETDEWEB)

    Lookman, R.; Vanermen, G.; Van De Weghe, H.; Gemoets, J. [Vito, Mol (Belgium); Van der Sterren, G.; Alphenaar, A. [TTE, Deventer (Netherlands)

    2005-07-01

    Several methods are available for the characterization of petroleum hydrocarbons. The TPHCWG (Total Petroleum Hydrocarbon Criteria Working Group) developed a method based on a silica column separation of aromatics and aliphatics and a GC-FID subdivision into equivalent-carbon fractions (EC) ('TPH-method'). This method was mainly developed for assessing human risks of oil compounds. Within NOBIS (Dutch Research program Biological In-situ Remediation), another method was developed based upon an equilibrium-experiment of the oil-polluted soil with water (column recirculation), which was further developed by TTE ('TTE-method'). This method uses measured water solubilities of individual oil components and GC-retention times yielding a subdivision of the hydrocarbons into compound classes that are relevant for assessing the remediation potential of the specific oil pollution. In this paper we present results of a research project in which we developed a new method, the 'OK-method' that combines these two procedures and allows a complete characterisation of the oil in terms of composition, (human) risks, volatility, solubility, plume behaviour (migration velocities of the soluble components) and aerobic degradation potential. (authors)

  16. 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

  17. Total mercury and methylmercury fluxes via emerging insects in recently flooded hydroelectric reservoirs and a natural lake

    International Nuclear Information System (INIS)

    Tremblay, Alain; Lucotte, Marc; Cloutier, Louise

    1998-01-01

    Total mercury (total Hg) concentrations in emerging aquatic insects ranged from 140 to 1500 ng g -1 dry wt. in two hydroelectric reservoirs of northern Quebec compared with 50-160 ng g -1 dry wt. in a natural lake. Methylmercury (MeHg) concentrations were somewhat lower, ranging from 35 to 800 ng Hg g -1 dry wt. in reservoirs and from 29 to 90 ng g -1 dry wt. in the natural lake. Contamination of insect taxa of reservoirs was on average 2-3 times higher than their counterparts in the natural lake. There was no difference between total Hg and MeHg concentrations of insects sampled from flooded forest soils and flooded peatland, although total Hg and MeHg concentrations differed between flooded peatland and flooded forest soils themselves. Insect biomasses were approx. two times higher in the reservoirs than in the natural lake (580-2200 mg m -2 year -1 dry wt., 950 mg m -2 year -1 dry wt., respectively); chironomids dominated in the reservoirs and trichopterans dominated in the natural lake. Similarly, total MeHg fluxes via emerging insects were approx. 2-4 times higher in reservoirs than that of the natural lake (55-224 ng MeHg m -2 year -1 dry wt., 74 ng MeHg m -2 year -1 dry wt., respectively). Our results show the importance of the insect community in the transfer of MeHg from flooded soils and flooded peatlands to fish, and that this pathway probably makes a significant contribution to the rapid rise of Hg levels in the fish community after flooding

  18. The effects of cultivation on the organic matter of total soil and in the different soil particle size separates using radiocarbon dating

    International Nuclear Information System (INIS)

    Gazineu, M.H.P.

    1982-07-01

    The effects of cultivation on the organic matter and nutrients in the total soil and in five particle size separates were studied through chemical analyses and radiocarbon dating. Samples were taken from the A and B horizons of an uncultivated field and of fields cultivated during 5,60 and 90 years which had never received treatment with fertilizers. (M.A.) [pt

  19. Time and moisture effects on total and bioavailable copper in soil water extracts

    DEFF Research Database (Denmark)

    Tom-Petersen, Andreas; Hansen, H.C.B.; Nybroe, O.

    2004-01-01

    Environmental risk assessment of heavy metals in soil frequently involves testing of freshly spiked soils kept under stable humidity conditions, but it has been questioned whether these assessments are representative of the field situation. Furthermore, the poor correspondence that is often found...

  20. METHODS FOR THE DETERMINATION OF TOTAL ORGANIC CARBON (TOC) IN SOILS AND SEDIMENTS

    Science.gov (United States)

    Organic matter in soils and sediments is widely distributed over the earth's surface occurring in almost all terrestrial and aquatic environments (Schnitzer, 1978). Soils and sediments contain a large variety of organic materials ranging from simple sugars and carbohydrates to th...

  1. 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.

  2. Assessment of Hg contamination and exposure to miners and schoolchildren at a small-scale gold mining and recovery operation in Thailand.

    Science.gov (United States)

    Umbangtalad, S; Parkpian, P; Visvanathan, C; Delaune, R D; Jugsujinda, A

    2007-12-01

    Gold extracted by Hg-amalgamation process, which can cause both health and environmental problems, is widespread in South East Asia including Myanmar, Laos, Cambodia, and Thailand. Small-scale gold mining operations have been carried out since the year 2000 in Phanom Pha District, Phichit Province, Thailand. Since no data is available for evaluating Hg exposure, an investigation of mercury (Hg) contamination and exposure assessment was carried out at this mine site. Environmental monitoring illustrated the total Hg in water was as high as 4 microg/l while Hg in sediment ranged between 102 to 325 microg/kg dry weight. Both Hg deposition from the air (1.28 microg/100 cm(2)/day) and concentration in surface soil (20,960 microg/kg dry weight) were elevated in the area of amalgamation. The potential of Hg exposure to miners as well as to schoolchildren was assessed. The concentrations of Hg in urine of 79 miners who were directly (group I) or indirectly (group II) involved in the gold recovery operation were 32.02 and 20.04 microg/g creatinine, respectively, which did not exceed regulatory limits (35 microg/g creatinine). Hair Hg levels in both groups (group I and group II) also were not significantly higher than the non-exposed group. In terms of risk factors, gender and nature of food preparation and consumption were the two significant variables influencing the concentration of Hg in urine of miners (P mining process. In a second Hg exposure assessment, a group of 59 schoolchildren who attended an elementary school near the gold mine site was evaluated for Hg exposure. A slightly higher Hg urine concentration was detected in group I and group II (involved and not involved in gold recovery) at average levels of 15.82 and 9.95 microg/g creatinine, respectively. The average Hg values for both groups were below the established levels indicating no risk from Hg intake. Average Hg hair level in all schoolchildren (0.93 microg/g) was not significantly higher than reference

  3. Establishment of five cover crops and total soil nutrient extraction in a humid tropical soil in the Peruvian Amazon

    Science.gov (United States)

    In order to evaluate the establishment of five cover crops and their potential to increase soil fertility through nutrient extraction, an experiment was installed in the Research Station of Choclino, San Martin, Peru. Five cover crops were planted: Arachis pintoi Krapov. & W.C. Greg, Calopogonium m...

  4. Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi.

    Science.gov (United States)

    Tran, Thi Anh Thu; Dinh, Quang Toan; Cui, Zeiwei; Huang, Jie; Wang, Dan; Wei, Tianjiao; Liang, Dongli; Sun, Xin; Ning, Ping

    2018-01-01

    Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se 4+ and Se 6+ ) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl 2 ) and selenite (Na 2 SeO 3 ) or selenate (Na 2 SeO 4 ) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg I R values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), I R values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the I R indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se 4+ or Se 6+ ). Copyright © 2017

  5. Mobility and contamination assessment of mercury in coal fly ash, atmospheric deposition, and soil collected from Tianjin, China.

    Science.gov (United States)

    Wei, Zheng; Wu, Guanghong; Su, Ruixian; Li, Congwei; Liang, Peiyu

    2011-09-01

    Samples of class F coal fly ash (levels I, II, and III), slag, coal, atmospheric deposition, and soils collected from Tianjin, China, were analyzed using U.S. Environmental Protection Agency (U.S. EPA) Method 3052 and a sequential extraction procedure, to investigate the pollution status and mobility of Hg. The results showed that total mercury (HgT) concentrations were higher in level I fly ash (0.304 µg/g) than in level II and level III fly ash and slag (0.142, 0.147, and 0.052 µg/g, respectively). Total Hg in the atmospheric deposition was higher during the heating season (0.264 µg/g) than the nonheating season (0.135 µg/g). Total Hg contents were higher in suburban area soils than in rural and agricultural areas. High HgT concentrations in suburban area soils may be a result of the deposition of Hg associated with particles emitted from coal-fired power plants. Mercury in fly ash primarily existed as elemental Hg, which accounted for 90.1, 85.3, and 90.6% of HgT in levels I, II, and III fly ash, respectively. Mercury in the deposition existed primarily as sulfide Hg, which accounted for 73.8% (heating season) and 74.1% (nonheating season) of HgT. However, Hg in soils existed primarily as sulfide Hg, organo-chelated Hg and elemental Hg, which accounted for 37.8 to 50.0%, 31.7 to 41.8%, and 13.0 to 23.9% of HgT, respectively. The percentage of elemental Hg in HgT occurred in the order fly ash > atmospheric deposition > soils, whereas organo-chelated Hg and sulfide Hg occurred in the opposite order. The present approach can provide a window for understanding and tracing the source of Hg in the environment in Tianjin and the risk associated with Hg bioaccessibility. Copyright © 2011 SETAC.

  6. TOTAL AND HOT-WATER EXTRACTABLE CARBON RELATIONSHIP IN CHERNOZEM SOIL UNDER DIFFERENT CROPPING SYSTEMS AND LAND USE

    Directory of Open Access Journals (Sweden)

    Srdjan Šeremešić

    2013-12-01

    Full Text Available A study was conducted to determine the hot water extractable organic carbon (HWOC in 9 arable and 3 non arable soil samples on Haplic Chernozem. The hot water extractable carbon represents assimilative component of the total organic matter (OM that could contain readily available nutrients for plant growth. The obtained fraction of organic carbon (C makes up only a small percentage of the soil OM and directly reflects the changes in the rhizosphere. This labile fraction of the organic matter was separated by hot water extraction at 80°C. In our study the HWOC content in different samples ranged from 125 mg g-1 to 226 mg g-1. On the plots that are under native vegetation, higher values were determined (316 mg g-1 to 388 mg g-1. Whereas samples from arable soils were lower in HWOC. It was found that this extraction method can be successfully used to explain the dynamics of the soil OM. Soil samples with lower content of the total OM had lower HWOC content, indicating that the preservation of the OM depends on the renewal of its labile fractions.

  7. Chemical attributes, total organic carbon stock and humified fractions of organic matter soil submitted to different systems of sugarcane management

    Directory of Open Access Journals (Sweden)

    Jean Sérgio Rosset

    2014-10-01

    Full Text Available Mechanized harvesting maintenance of trash from cane sugar and soil application of waste as vinasse and filter cake can improve the system of crop yield. Thus, this study aimed to evaluate the changes in the chemical, the stock of total organic carbon and humified organic matter fractions in an Oxisol cultivated with cane sugar with the following management systems: with sugarcane vinasse application (CCV, without application of burnt cane waste (CQS, with burnt cane vinasse application (CQV, with application of burnt cane filter cake (CQTF and burnt cane with joint application of vinasse and filter cake (CQVTF. For reference we used an area of natural vegetation (NV, Cerrado sensu stricto. Treatment CQVTF showed improvement in soil chemical properties, increased inventory levels of total organic carbon – TOC (values ranging from 21.28 to 40.02 Mg ha-1 and humified fractions of soil organic matter in relation to other treatments. The CQS area at a depth of 0-0.05 m, showed the greatest losses of soil TOC stocks (56.3% compared to NV. The adoption of management presented CCV and chemical attributes of the soil TOC stocks equivalent to those observed in areas with CQV CQTF and despite the short period of adoption (3 years. The TOC correlated with the sum of bases (r = 0.76 **, cation exchange capacity (r = 0.59 ** and base saturation (r = 0.63 **, while the humic acids (r = 0.40 ** fulvic acids (r = 0.49 ** and humin (r = 0.59 ** correlated with the cation exchange capacity of the soil. These results indicate that the preservation of trash in the management of cane sugar added to the application of vinasse and filter cake increases the TOC stocks promoting improvement in soil chemical properties.

  8. Research and Evaluation of Relief Effect on Total Carbon Changes in Soil

    Directory of Open Access Journals (Sweden)

    Mantas Pranskevičius

    2011-04-01

    Full Text Available Soil is one of the major subsystems of the natural landscape of land and serves to the man as the main source of food resources for exclusive importance. One of the burning problems of mankind in the future will be the preservation of land soils, their fertility and health status under conditions of the increased pressure of human and the degradation of natural landscape conditions. As an additional negative factor taking place in nature is that the Earth will have to overcome the effects of global warming that will inevitably occur in Lithuanian agriculture. This paper examines the general evolution of carbon considering relief. Currently, the erosion of soil surface in Lithuania makes 30–50 %. Soil affected by erosion losses its fertility thus promoting further degradation of land.Article in Lithuanian

  9. Contribution of orchardgrass and white clover roots to total soil respiration

    Science.gov (United States)

    Understanding ecosystem carbon dioxide flux requires knowledge of component fluxes including photosynthetic uptake and respiratory loss. Experimental separation of soil respiration into its heterotrophic and autotrophic components has been difficult, complicating efforts to quantify management and e...

  10. Total organic carbon and humus fractions in restored soils from limestone quarries in semiarid climate, SE Spain

    Science.gov (United States)

    Luna Ramos, Lourdes; Miralles Mellado, Isabel; Ángel Domene Ruiz, Miguel; Solé Benet, Albert

    2016-04-01

    Mining activities generate erosion and loss of plant cover and soil organic matter (SOM), especially in arid and semiarid Mediterranean regions. A precondition for ecosystem restoration in such highly disturbed areas is the development of functional soils with sufficient organic matter. But the SOM quality is also important to long-term C stabilization. The resistance to biodegradation of recalcitrant organic matter fractions has been reported to depend on some intrinsic structural factors of humic acid substances and formation of amorphous organo-mineral recalcitrant complexes. In an experimental soil restoration in limestone quarries in the Sierra de Gádor (Almería), SE Spain, several combinations of organic amendments (sewage sludge and compost from domestic organic waste) and mulches (gravel and woodchip) were added in experimental plots using a factorial design. In each plot, 75 native plants (Anthyllis cytisoides, A. terniflora and Macrochloa tenacissima) were planted and five years after the start of the experiment total organic carbon (TOC), physico-chemical soil properties and organic C fractions (particulate organic matter, H3PO4-fulvic fraction, fulvic acids (FA), humic acids (HA) and humin) were analyzed. We observed significant differences between treatments related to the TOC content and the HA/FA ratio. Compost amendments increased the TOC, HA content and HA/FA ratio, even higher than in natural undisturbed soils, indicating an effective clay humus-complex pointing to progressively increasing organic matter quality. Soils with sewage sludge showed the lowest TOC and HA/FA ratio and accumulated a lower HA proportion indicating poorer organic matter quality and comparatively lower resilience than in natural soils and soils amended with compost.

  11. Prospects of using leguminous species in phytoremediation of total petroleum hydrocarbons polluted soils

    Directory of Open Access Journals (Sweden)

    Smaranda Masu

    2014-05-01

    Full Text Available Selecting the plant species to grow on aged petroleum hydrocarbons polluted soils is an important factor for a successful phytoremediation. Phytoremediation is a green technology that can become a promising solution for decontaminating polluted soils and ecological restoration of the landscape. Our comparative studies evaluate the effect of oil hydrocarbon pollution with high initial concentration on the growth leguminous plant species: Vicia sativa and Glycine max. The experimental block contains control variants, polluted soil unfertilized / fertilized with municipal sludge anaerobically stabilized in absence/presence of modified volcanic tuff amendment. After period of time the experiment’s soil in which plant species had grown well was sampled and analyzed for petroleum hydrocarbons removal. Both species showed promising efficiency in the phytoremediation of petroleum hydrocarbon highly polluted soils but a reduced growth of the surveyed plants was noticed. The efficiency of the petroleum hydrocarbons diminution is increased in the case of the addition of fertilizer 16.6 % for Vicia sativa and 30 % for Glycine max vs. the initial quantity. In the case of the phytoremediation of polluted soils treated with fertilizer and volcanic tuff, the efficiency of the petroleum hydrocarbons reduction was 72.9 % for Vicia sativa and 53.7 % for Glycine max.

  12. Standard test method for analysis of total and isotopic uranium and total thorium in soils by inductively coupled plasma-mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the measurement of total uranium (U) and thorium (Th) concentrations in soils, as well as the determination of the isotopic weight percentages of 234U, 235U, 236U, and 238U, thereby allowing for the calculation of individual isotopic uranium activity or total uranium activity. This inductively coupled plasma-mass spectroscopy (ICP-MS) method is intended as an alternative analysis to methods such as alpha spectroscopy or thermal ionization mass spectroscopy (TIMS). Also, while this test method covers only those isotopes listed above, the instrumental technique may be expanded to cover other long-lived radioisotopes since the preparation technique includes the preconcentration of the actinide series of elements. The resultant sample volume can be further reduced for introduction into the ICP-MS via an electrothermal vaporization (ETV) unit or other sample introduction device, even though the standard peristaltic pump introduction is applied for this test method. The sample preparatio...

  13. Total and Bioaccessible Soil Arsenic and Lead Levels and Plant Uptake in Three Urban Community Gardens in Puerto Rico

    Directory of Open Access Journals (Sweden)

    John Misenheimer

    2018-01-01

    Full Text Available Arsenic (As and lead (Pb are two contaminants of concern associated with urban gardening. In Puerto Rico, data currently is limited on As and Pb levels in urban garden soils, soil metal (loid bioaccessibility, and uptake of As and Pb in soil by edible plants grown in the region. This study examined total and bioaccessible soil As and Pb concentrations and accumulation in 10 commonly grown garden plants collected from three urban community gardens in Puerto Rico. Bioavailability values were predicted using bioaccessibility data to compare site-specific bioavailability estimates to commonly used default exposure assumptions. Total and bioaccessible As levels in study soils ranged from 2 to 55 mg/kg and 1 to 18 mg/kg, respectively. Total and bioaccessible Pb levels ranged from 19 to 172 mg/kg and 17 to 97 mg/kg, respectively. Measured bioaccessibility values corresponded to 19% to 42% bioaccessible As and 61% to 100% bioaccessible Pb when expressed as a percent of total As and Pb respectively. Predicted relative percent bioavailability of soil As and Pb based on measured bioaccessibility values ranged from 18% to 36% and 51% to 85% for As and Pb respectively. Transfer factors (TFs measuring uptake of As in plants from soil ranged from 0 to 0.073 in the edible flesh (fruit or vegetable of plant tissues analyzed and 0.073 to 0.444 in edible leaves. Pb TFs ranged from 0.002 to 0.012 in flesh and 0.023 to 0.204 in leaves. Consistent with TF values, leaves accumulated higher concentrations of As and Pb than the flesh, with the highest tissue concentrations observed in the culantro leaf (3.2 mg/kg dw of As and 8.9 mg/kg dw of Pb. Leaves showed a general but not statistically-significant (α = 0.05 trend of increased As and Pb concentration with increased soil levels, while no trend was observed for flesh tissues. These findings provide critical data that can improve accuracy and reduce uncertainty when conducting site-specific risk determination of

  14. 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

  15. Transport mechanisms of soil-bound mercury in the erosion process during rainfall-runoff events.

    Science.gov (United States)

    Zheng, Yi; Luo, Xiaolin; Zhang, Wei; Wu, Xin; Zhang, Juan; Han, Feng

    2016-08-01

    Soil contamination by mercury (Hg) is a global environmental issue. In watersheds with a significant soil Hg storage, soil erosion during rainfall-runoff events can result in nonpoint source (NPS) Hg pollution and therefore, can extend its environmental risk from soils to aquatic ecosystems. Nonetheless, transport mechanisms of soil-bound Hg in the erosion process have not been explored directly, and how different fractions of soil organic matter (SOM) impact transport is not fully understood. This study investigated transport mechanisms based on rainfall-runoff simulation experiments. The experiments simulated high-intensity and long-duration rainfall conditions, which can produce significant soil erosion and NPS pollution. The enrichment ratio (ER) of total mercury (THg) was the key variable in exploring the mechanisms. The main study findings include the following: First, the ER-sediment flux relationship for Hg depends on soil composition, and no uniform ER-sediment flux function exists for different soils. Second, depending on soil composition, significantly more Hg could be released from a less polluted soil in the early stage of large rainfall events. Third, the heavy fraction of SOM (i.e., the remnant organic matter coating on mineral particles) has a dominant influence on the enrichment behavior and transport mechanisms of Hg, while clay mineral content exhibits a significant, but indirect, influence. The study results imply that it is critical to quantify the SOM composition in addition to total organic carbon (TOC) for different soils in the watershed to adequately model the NPS pollution of Hg and spatially prioritize management actions in a heterogeneous watershed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Huerta del Rey: Edafic Characterization of a Historic Area of the Mercury Mining and Study of the Transfer of Mercury from the Soil to Plantago Major

    International Nuclear Information System (INIS)

    Suarez, C.; Manero, L.; Sierra, M. J.; Rodriguez-Alonso, M.; Millan, R.

    2013-01-01

    The main objective of this scientific-technical report is to carry out a characterization of study plot called Huerta del Rey in the mercury (Hg) mining district of Almaden. For this goal, an edaphic characterization has been performed and the Hg behavior in the soil study has been evaluated. Then, total Hg concentration and easily available Hg for plants have been determined and the absorption and distribution of Hg in Plantago major L (typical specie from the study area) have been studied. The results showed that the total Hg concentrations in the soil ranged from 530 ± 32 mg kg - 1 to 4300 ± 339 mg kg - 1 even to 12378 ± 1051mg kg - 1. It is in accordance with the normal values measured in a Hg mining area. Otherwise, the percentage of soluble Hg in soil with respect to the total Hg concentration is low ( - 1 that could mean a potential risk of pollution of groundwater by leaching process. Finally a brief description about different technologies for decreasing Hg concentration in the study soil, including phytoremediation, has been performed. (Author) 96 refs.

  17. Total (fumarolic?+?diffuse soil) CO2 output from Furnas volcano

    OpenAIRE

    Pedone, M.; Viveiros, F.; Aiuppa, A.; Giudice, G.; Grassa, F.; Gagliano, A. L.; Francofonte, V.; Ferreira, T.

    2015-01-01

    Furnas volcano, in S?o Miguel island (Azores), being the surface expression of rising hydrothermal steam, is the site of intense carbon dioxide (CO2) release by diffuse degassing and fumaroles. While the diffusive CO2 output has long (since the early 1990s) been characterized by soil CO2 surveys, no information is presently available on the fumarolic CO2 output. Here, we performed (in August 2014) a study in which soil CO2 degassing survey was combined for the first time with the measurement ...

  18. Investigation of ethyl lactate as a green solvent for desorption of total petroleum hydrocarbons (TPH) from contaminated soil.

    Science.gov (United States)

    Jalilian Ahmadkalaei, Seyedeh Pegah; Gan, Suyin; Ng, Hoon Kiat; Abdul Talib, Suhaimi

    2016-11-01

    Treatment of oil-contaminated soil is a major environmental concern worldwide. The aim of this study is to examine the applicability of a green solvent, ethyl lactate (EL), in desorption of diesel aliphatic fraction within total petroleum hydrocarbons (TPH) in contaminated soil and to determine the associated desorption kinetics. Batch desorption experiments were carried out on artificially contaminated soil at different EL solvent percentages (%). In analysing the diesel range of TPH, TPH was divided into three fractions and the effect of solvent extraction on each fraction was examined. The experimental results demonstrated that EL has a high and fast desorbing power. Pseudo-second order rate equation described the experimental desorption kinetics data well with correlation coefficient values, R 2 , between 0.9219 and 0.9999. The effects of EL percentage, initial contamination level of soil and liquid to solid ratio (L/S (v/w)) on initial desorption rate have also been evaluated. The effective desorption performance of ethyl lactate shows its potential as a removal agent for remediation of TPH-contaminated soil worldwide.

  19. Distribution of Total and Organic Mercury in Superficial Soils in the Upper Manzanares River Watershed, Sucre State, Venezuela

    Directory of Open Access Journals (Sweden)

    Yahsé Rojas Challa

    2008-01-01

    Full Text Available Total and organic mercury contents were determined from samples of surface soils (0-5 cm, sieved at ≤ 63µm, collected from 10 different locations in the upper Manzanares River watershed, using cold vapor atomic absorption spectroscopy. Methylmercury was determined using a HPLC-UV detector. The mean total mercury concentration was 1.3 μg.g-1, a value permitted by the Canadian environment quality guidelines for farming soils, but high for European standards. Using certified reference materials, we verified that a modification of the method described by Qian et al. (2000 was effective for organic mercury extraction, with a recovery of 92.17% for DORM-2 and 92.11% for TORT-2. This modified method was applied to soil samples, obtaining concentrations of 0.5-1.0 μg.g-1 of organic mercury. The parameters for determining methylmercury using HPLC-UV were optimized; the best results were obtained with a 4.6 mm x 25 cm Zorbax CN column, with a mobile phase of 70/30 V/V of methanol: ammonium acetate 0.05 mol.l-1, with a flow rate of 0.5 ml.min-1; the methylmercury was detected at 4.99 min retention time. Methylmercury was not found in the soil samples. Using the certified reference material we proved that the method used produced reliable results. The analysis confirmed the existence of mercury in this farming area.

  20. 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.

  1. Mercury transformation and release differs with depth and time in a contaminated riparian soil during simulated flooding

    Science.gov (United States)

    Poulin, Brett; Aiken, George R.; Nagy, Kathryn L.; Manceau, Alain; Krabbenhoft, David P.; Ryan, Joseph N.

    2016-01-01

    Riparian soils are an important environment in the transport of mercury in rivers and wetlands, but the biogeochemical factors controlling mercury dynamics under transient redox conditions in these soils are not well understood. Mercury release and transformations in the Oa and underlying A horizons of a contaminated riparian soil were characterized in microcosms and an intact soil core under saturation conditions. Pore water dynamics of total mercury (HgT), methylmercury (MeHg), and dissolved gaseous mercury (Hg0(aq)) along with selected anions, major elements, and trace metals were characterized across redox transitions during 36 d of flooding in microcosms. Next, HgT dynamics were characterized over successive flooding (17 d), drying (28 d), and flooding (36 d) periods in the intact core. The observed mercury dynamics exhibit depth and temporal variability. At the onset of flooding in microcosms (1–3 d), mercury in the Oa horizon soil, present as a combination of ionic mercury (Hg(II)) bound to thiol groups in the soil organic matter (SOM) and nanoparticulate metacinnabar (b-HgS), was mobilized with organic matter of high molecular weight. Subsequently, under anoxic conditions, pore water HgT declined coincident with sulfate (3–11 d) and the proportion of nanoparticulate b-HgS in the Oa horizon soil increased slightly. Redox oscillations in the intact Oa horizon soil exhausted the mobile mercury pool associated with organic matter. In contrast, mercury in the A horizon soil, present predominantly as nanoparticulate b-HgS, was mobilized primarily as Hg0(aq) under strongly reducing conditions (5–18 d). The concentration of Hg0(aq) under dark reducing conditions correlated positively with byproducts of dissimilatory metal reduction (P(Fe,Mn)). Mercury dynamics in intact A horizon soil were consistent over two periods of flooding, indicating that nanoparticulate b-HgS was an accessible pool of mobile mercury over recurrent reducing conditions. The

  2. Predicting Soil Organic Carbon and Total Nitrogen in the Russian Chernozem from Depth and Wireless Color Sensor Measurements

    Science.gov (United States)

    Mikhailova, E. A.; Stiglitz, R. Y.; Post, C. J.; Schlautman, M. A.; Sharp, J. L.; Gerard, P. D.

    2017-12-01

    Color sensor technologies offer opportunities for affordable and rapid assessment of soil organic carbon (SOC) and total nitrogen (TN) in the field, but the applicability of these technologies may vary by soil type. The objective of this study was to use an inexpensive color sensor to develop SOC and TN prediction models for the Russian Chernozem (Haplic Chernozem) in the Kursk region of Russia. Twenty-one dried soil samples were analyzed using a Nix Pro™ color sensor that is controlled through a mobile application and Bluetooth to collect CIEL*a*b* (darkness to lightness, green to red, and blue to yellow) color data. Eleven samples were randomly selected to be used to construct prediction models and the remaining ten samples were set aside for cross validation. The root mean squared error (RMSE) was calculated to determine each model's prediction error. The data from the eleven soil samples were used to develop the natural log of SOC (lnSOC) and TN (lnTN) prediction models using depth, L*, a*, and b* for each sample as predictor variables in regression analyses. Resulting residual plots, root mean square errors (RMSE), mean squared prediction error (MSPE) and coefficients of determination ( R 2, adjusted R 2) were used to assess model fit for each of the SOC and total N prediction models. Final models were fit using all soil samples, which included depth and color variables, for lnSOC ( R 2 = 0.987, Adj. R 2 = 0.981, RMSE = 0.003, p-value < 0.001, MSPE = 0.182) and lnTN ( R 2 = 0.980 Adj. R 2 = 0.972, RMSE = 0.004, p-value < 0.001, MSPE = 0.001). Additionally, final models were fit for all soil samples, which included only color variables, for lnSOC ( R 2 = 0.959 Adj. R 2 = 0.949, RMSE = 0.007, p-value < 0.001, MSPE = 0.536) and lnTN ( R 2 = 0.912 Adj. R 2 = 0.890, RMSE = 0.015, p-value < 0.001, MSPE = 0.001). The results suggest that soil color may be used for rapid assessment of SOC and TN in these agriculturally important soils.

  3. Comparison of inductively coupled plasma mass spectrometry and colorimetric determination of total and extractable phosphorus in soils

    International Nuclear Information System (INIS)

    Ivanov, Krasimir; Zaprjanova, Penka; Petkova, Milena; Stefanova, Violeta; Kmetov, Veselin; Georgieva, Deyana; Angelova, Violina

    2012-01-01

    The most widely used method for determination of total phosphorus in soils is perchloric acid digestion, followed by a colorimetric assay to measure the concentration of P in solution. The first part of this study compares an alternative digestion method, using aqua regia (ISO 11466 and EPA Method 3052), with perchloric acid digestion procedure, and also compares inductively coupled plasma mass spectroscopy (ICP-MS) with colorimetry for the measurement of P on the basis of five internationally certified standard soils and 20 real-life soils with widely different extractability of phosphorus. The phosphorus concentration was determined by means of the reduced phosphomolybdenum blue and ICP-MS. The relationship between methods has been examined statistically. Good agreement of the results from colorimetry and ICP-MS was established for all certified soils. The microwave-assisted digestion with aqua regia was comparable, both in precision and accuracy, with the hot plate aqua regia method. The phosphorus concentration found with the HF + HClO 4 digestion method was in good agreement with the certified mean values, while the superiority in extracting phosphorus, when compared to other methods, was obvious. Soil testing for plant-available phosphorus in Bulgaria and many European countries is most commonly conducted using acid Ca-lactate extraction (Egner–Riehm test) and alkaline sodium bicarbonate extraction (BDS ISO 11263:2002), based on Olsen test, followed by a colorimetric assay to measure the concentration of P in solution. The second part of this study reports the differences between Egner–Riehm test and BDS ISO 11263:2002 measured colorimetrically and by ICP-MS. Fifty soils were selected from South Bulgaria to represent a wide range of soil properties. It was established that ICP-MS consistently yielded significantly higher P concentrations than the colorimetric method in both extraction tests, and the relative differences were greatest in soils with lower P

  4. Comparison of inductively coupled plasma mass spectrometry and colorimetric determination of total and extractable phosphorus in soils

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Krasimir, E-mail: kivanov1@abv.bg [Department of Chemistry, University of Agriculture, Plovdiv (Bulgaria); Zaprjanova, Penka [Tobacco and Tobacco Products Institute, Plovdiv (Bulgaria); Petkova, Milena [Department of Chemistry, University of Agriculture, Plovdiv (Bulgaria); Stefanova, Violeta; Kmetov, Veselin; Georgieva, Deyana [Department of Analytical Chemistry, Plovdiv University ' Paisii Hilendarski,' Plovdiv (Bulgaria); Angelova, Violina [Department of Chemistry, University of Agriculture, Plovdiv (Bulgaria)

    2012-05-15

    The most widely used method for determination of total phosphorus in soils is perchloric acid digestion, followed by a colorimetric assay to measure the concentration of P in solution. The first part of this study compares an alternative digestion method, using aqua regia (ISO 11466 and EPA Method 3052), with perchloric acid digestion procedure, and also compares inductively coupled plasma mass spectroscopy (ICP-MS) with colorimetry for the measurement of P on the basis of five internationally certified standard soils and 20 real-life soils with widely different extractability of phosphorus. The phosphorus concentration was determined by means of the reduced phosphomolybdenum blue and ICP-MS. The relationship between methods has been examined statistically. Good agreement of the results from colorimetry and ICP-MS was established for all certified soils. The microwave-assisted digestion with aqua regia was comparable, both in precision and accuracy, with the hot plate aqua regia method. The phosphorus concentration found with the HF + HClO{sub 4} digestion method was in good agreement with the certified mean values, while the superiority in extracting phosphorus, when compared to other methods, was obvious. Soil testing for plant-available phosphorus in Bulgaria and many European countries is most commonly conducted using acid Ca-lactate extraction (Egner-Riehm test) and alkaline sodium bicarbonate extraction (BDS ISO 11263:2002), based on Olsen test, followed by a colorimetric assay to measure the concentration of P in solution. The second part of this study reports the differences between Egner-Riehm test and BDS ISO 11263:2002 measured colorimetrically and by ICP-MS. Fifty soils were selected from South Bulgaria to represent a wide range of soil properties. It was established that ICP-MS consistently yielded significantly higher P concentrations than the colorimetric method in both extraction tests, and the relative differences were greatest in soils with lower

  5. Mercury in soil, vegetable and human hair in a typical mining area in China: Implication for human exposure.

    Science.gov (United States)

    Jia, Qin; Zhu, Xuemei; Hao, Yaqiong; Yang, Ziliang; Wang, Qi; Fu, Haihui; Yu, Hongjin

    2018-06-01

    Concentrations of total mercury (T-Hg) and methylmercury (MeHg) in soil, vegetables, and human hair were measured in a mercury mining area in central China. T-Hg and MeHg concentrations in soil ranged from 1.53 to 1054.97mg/kg and 0.88 to 46.52μg/kg, respectively. T-Hg concentrations was correlated with total organic carbon (TOC) content (R 2 =0.50, p<0.01) and pH values (R 2 =0.21, p<0.05). A significant linear relationship was observed between MeHg concentrations and the abundance of sulfate-reducing bacteria (SRB) (R 2 =0.39, p<0.05) in soil. Soil incubation experiments amended with specific microbial stimulants and inhibitors showed that Hg methylation was derived from SRB activity. T-Hg and MeHg concentrations in vegetables were 24.79-781.02μg/kg and 0.01-0.18μg/kg, respectively; levels in the edible parts were significantly higher than in the roots (T-Hg: p<0.05; MeHg: p<0.01). Hg species concentrations in rhizosphere soil were positively correlated to those in vegetables (p<0.01), indicating that soil was an important source of Hg in vegetables. Risk assessment indicated that the consumption of vegetables could result in higher probable daily intake (PDI) of T-Hg than the provisional tolerable daily intake (PTDI) for both adults and children. In contrast, the PDI of MeHg was lower than the reference dose. T-Hg and MeHg concentrations in hair samples ranged from 1.57 to 12.61mg/kg and 0.04 to 0.94mg/kg, respectively, and MeHg concentration in hair positively related to PDI of MeHg via vegetable consumption (R 2 =0.39, p<0.05), suggesting that vegetable may pose health risk to local residents. Copyright © 2017. Published by Elsevier B.V.

  6. 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.

  7. Evaluating the impact of extraction and cleanup parameters on the yield of total petroleum hydrocarbons in soil

    Energy Technology Data Exchange (ETDEWEB)

    Saari, Eija; Peraemaeki, Paavo; Jalonen, Jorma [University of Oulu, Department of Chemistry (Finland)

    2008-11-15

    Interlaboratory comparisons for the analysis of mineral oil in polluted soil using the GC-FID method indicate that extraction and cleanup conditions have significant effects on the analytical results. In this investigation a ruggedness test was performed on the extraction and cleanup method for the determination of total petroleum hydrocarbons in soil. A two-level Plackett-Burman design was utilized to study the effect of 11 different method parameters on the extraction recovery of total petroleum hydrocarbons (TPH) in soil. Both qualitative and quantitative factors were investigated. The results indicate that total petroleum hydrocarbons can be relatively reliably monitored through strict implementation of the ISO and CEN draft standards. However, variation in certain method parameters readily affects the validity of the results. The most critical factors affecting TPH recovery were the solvent and co-solvent used for extraction, the extraction time, adsorbent and its weight and sample TPH concentration. Because adaptation of the draft standards especially with respect to these factors easily leads to TPH recoveries higher than 200% or lower than 70%, the validity of the adapted method should always be verified. A proper estimate of the expanded uncertainty should also be appended to TPH results, because only then can the reliability of the results be guaranteed and further justification is gained to support the end-use of the data. This also supports the credibility of the analytical services and prevents the data end-users from drawing misleading conclusions concerning the environmental risks and potential remediation requirements. (orig.)

  8. Decoupling of lignin and total litter decomposition across North American forest soils: a phenomenon to reconcile old and new paradigms of soil organic matter?

    Science.gov (United States)

    Hall, S. J.; Hammel, K.

    2017-12-01

    An "old" paradigm of soil organic matter (SOM) posited that biochemically "recalcitrant" lignin derivatives were a dominant constituent. Over the past decade(s), evidence for a newer paradigm has emerged which suggests that recalcitrance has little long-term impact on the biochemical composition of SOM, and that lignin is relatively unimportant in comparison with dead microbial biomass. Yet, methodological biases have hampered accurate quantification of lignin dynamics in mineral soils, and may have led to systematic underestimates of lignin stocks and turnover. Here, we sought to test this aspect of the "new" SOM paradigm. Synthetic position-specific 13C-labeled lignins provide a robust quantitative method to track the mineralization and fate of lignin moieties in mineral soils. Relatively few microbial taxa are known to depolymerize macromolecular lignin, and lignin derivatives can specifically associate with iron oxide mineral phases. Consequently, we hypothesized that decomposition of lignin is poorly correlated with total litter decomposition across ecosystems, and that lignin may represent a variable but significant component of decadal-cycling SOM. We incubated 10 forest soils spanning diverse North American ecosystems over seven months under laboratory conditions at constant temperature and moisture. Soils were incubated alone, with added C4 grass litter and natural isotope abundance lignin, and with added C4 litter and 13Cß-labeled lignin. These treatments allowed us to partition respiration for each soil from SOM, litter, and the Cß moiety of lignin—which is diagnostic for cleavage of the polymer. Consistent with our hypothesis, we found much greater variability (ten-fold) in cumulative lignin mineralization relative to bulk litter (two-fold) among soils. Multiple-pool first-order decay models implied that mean turnover times for lignin ranged from one to several decades among soils, relative to several years for bulk litter. Our results suggest a

  9. Total organic carbon in a soil recovered with sewage sludge and native species of the Atlantic Forest

    Science.gov (United States)

    Mara Lima Goulart, Lívia; Amaral Guerrini, Iraê; Fidalgo de Faria, Marianne; Spada, Grasiela; Proença Nalesso, Pedro Henrique; Willian Carlos, Guilherme

    2017-04-01

    The use of organic waste such as sewage sludge, in the recovery of degraded áreas have shown very satisfactory results, because they are constituted by high contentes of organic matter and nutrients, essential to improve the physical and chemical properties of the soil. Thus, the objective of this study was to verify the total organic carbon (TOC) of a degraded soil, up to a metre deep, after 10 years of application of sewage sludge and planting native species of the Atlantic forest. The experiment was conducted at Fazenda Entre-Rios, owned by Suzano Papel e Celulose, in Itatinga, São Paulo, Brazil. The experiment was designed as randomized block with four replications, six doses of sewage sludge (0, 2.5, 5, 10, 15 and 20 t ha-1), conventional chemical fertilizer and only with potassium application, totaling eight treatments. Samples were collected every 20 cm (0-20, 20-40, 40-60, 60-80 and 80-100 cm) until reaching a metre deep. Ten years after trial deployment, the sewage sludge application in degraded soil was significantly influenced the TOC at all depths sampled. The highest values of the COT were observed in plots that received 15 and 20 t ha-1 of sewage sludge, in all depths sampled, except for the layer of 80-100 cm, which presented the highest average COT in the treatment with 10 t ha-1 of residue. As observed for all treatments, the highest TOC averages were observed in the superficial layers of the soil (0-20 and 20-40 cm). The sewage sludge application is useful to recover degraded soils, as it improving their chemical characteristics and showing to be a good alternative to the final destination of this residue.

  10. The budget between transportation and accumulation of organic carbon and total nitrogen in black soil at a sloping farmland

    International Nuclear Information System (INIS)

    Fang Huajun; Zhang Xiaoping; Liang Aizhen

    2006-01-01

    Based on the rate of soil redistribution at a sloping farmland using 137 Cs tracer technique and spatial variation of soil organic carbon (SOC) and total nitrogen (TN), the spatial distribution of SOC and TN loss and the budget between transportation and accumulation for recently 50 years was calculated. The results showed that the rate of soil redistribution ranged from -24.61 t/hm 2 /a to 33.56 t/hm 2 /a, most of study area was in medium and weakly erosion phase and accounted for 83.66%; and the area of soil deposition accounted for 15.62%; The variation of the loss of SOC and TN was consistent with that of soil redistribution, shoulder-slope had the most serious loss with the rate of 407.57 kg/hm 2 /a for SOC and 39.94 kg/hm 2 /a for TN, back-slope and summit had the secondly loss with the average rate of 244.2 kg/hm 2 /a for SOC and -20.56 kg/hm 2 /a for TN. For the whole area, relative loss of SOC and TN more than 50% accounted for 10.45% and 11.21%, respectively; The net loss of sediment in the study area was 45.54 t/a for recent 48 years, among which SOC and TN were 612.62 kg/a and 47.20 kg/a, respectively, which was 52% more than that of without consideration of the enrichment of sediment on soil organic matter. (authors)

  11. Comparison between Random Forests, Artificial Neural Networks and Gradient Boosted Machines Methods of On-Line Vis-NIR Spectroscopy Measurements of Soil Total Nitrogen and Total Carbon

    Directory of Open Access Journals (Sweden)

    Said Nawar

    2017-10-01

    Full Text Available Accurate and detailed spatial soil information about within-field variability is essential for variable-rate applications of farm resources. Soil total nitrogen (TN and total carbon (TC are important fertility parameters that can be measured with on-line (mobile visible and near infrared (vis-NIR spectroscopy. This study compares the performance of local farm scale calibrations with those based on the spiking of selected local samples from both fields into an European dataset for TN and TC estimation using three modelling techniques, namely gradient boosted machines (GBM, artificial neural networks (ANNs and random forests (RF. The on-line measurements were carried out using a mobile, fiber type, vis-NIR spectrophotometer (305–2200 nm (AgroSpec from tec5, Germany, during which soil spectra were recorded in diffuse reflectance mode from two fields in the UK. After spectra pre-processing, the entire datasets were then divided into calibration (75% and prediction (25% sets, and calibration models for TN and TC were developed using GBM, ANN and RF with leave-one-out cross-validation. Results of cross-validation showed that the effect of spiking of local samples collected from a field into an European dataset when combined with RF has resulted in the highest coefficients of determination (R2 values of 0.97 and 0.98, the lowest root mean square error (RMSE of 0.01% and 0.10%, and the highest residual prediction deviations (RPD of 5.58 and 7.54, for TN and TC, respectively. Results for laboratory and on-line predictions generally followed the same trend as for cross-validation in one field, where the spiked European dataset-based RF calibration models outperformed the corresponding GBM and ANN models. In the second field ANN has replaced RF in being the best performing. However, the local field calibrations provided lower R2 and RPD in most cases. Therefore, from a cost-effective point of view, it is recommended to adopt the spiked European dataset

  12. Active and total microbial communities in forest soil are largely different and highly stratified during decomposition

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Petr; Kolařík, Miroslav; Štursová, Martina; Kopecký, J.; Valášková, Vendula; Větrovský, Tomáš; Žifčáková, Lucia; Šnajdr, Jaroslav; Rídl, Jakub; Vlček, Čestmír; Voříšková, Jana

    2012-01-01

    Roč. 6, č. 2 (2012), s. 248-258 ISSN 1751-7362 R&D Projects: GA ČR GA526/08/0751; GA MŠk LC06066 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z50520514 Keywords : cellulose decomposition * bacteria * forest soil Subject RIV: EE - Microbiology, Virology Impact factor: 8.951, year: 2012

  13. 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.

  14. Charcoal and Total Carbon in Soils from Foothills Shrublands to Subalpine Forests in the Colorado Front Range

    Directory of Open Access Journals (Sweden)

    Robert Sanford

    2012-10-01

    Full Text Available Temperate conifer forests in the Colorado Front Range are fire-adapted ecosystems where wildland fires leave a legacy in the form of char and charcoal. Long-term soil charcoal C (CC pools result from the combined effects of wildland fires, aboveground biomass characteristics and soil transfer mechanisms. We measured CC pools in surface soils (0–10 cm at mid-slope positions on east facing aspects in five continuous foothills shrubland and conifer forest types. We found a significant statistical effect of vegetation type on CC pools along this ecological gradient, but not a linear pattern increasing with elevation gain. There is a weak bimodal pattern of CC gain with elevation between foothills shrublands (1.2 mg CC ha−1 and the lower montane, ponderosa pine (1.5 mg CC ha−1 and Douglas-fir (1.5 mg CC ha−1 forest types prior to a mid-elevation decline in upper montane lodgepole pine forests (1.2 mg CC ha−1 before increasing again in the spruce/subalpine fir forests (1.5 mg CC ha−1. We propose that CC forms and accumulates via unique ecological conditions such as fire regime. The range of soil CC amounts and ratios of CC to total SOC are comparable to but lower than other regional estimates.

  15. 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

  16. Use of L-cysteine for minimization of inorganic Hg loss during thermal neutron irradiation

    International Nuclear Information System (INIS)

    Anderson, D.L.

    2009-01-01

    Thermal neutron irradiation experiments performed with cellulose-based L-cysteine-treated and untreated Hg standards showed Hg losses of 59-81% for untreated standards but only about a 0.2% loss for treated standards. These results and others for multielement standards showed that Hg loss is highly dependent on total mass and placement of materials in the irradiation vessel and that distribution of volatilized Hg was fairly uniform throughout the sample-containing region of the vessel. Polyethylene trapped volatile Hg much more efficiently than cellulose and a multielement standard containing inorganic Se selectively trapped Hg lost from a co-irradiated multielement standard containing Hg. (author)

  17. Huerta del Rey: Edafic Characterization of a Historic Area of the Mercury Mining and Study of the Transfer of Mercury from the Soil to Plantago Major; Huerta del Rey: Caracterizacion Edafica de una Zona Historica de la Mineria del Mercurio y Estudio de la Transferencia del Mercurio a Plantago Major

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, C; Manero, L; Sierra, M J; Rodriguez-Alonso, M; Millan, R

    2013-02-01

    The main objective of this scientific-technical report is to carry out a characterization of study plot called Huerta del Rey in the mercury (Hg) mining district of Almaden. For this goal, an edaphic characterization has been performed and the Hg behavior in the soil study has been evaluated. Then, total Hg concentration and easily available Hg for plants have been determined and the absorption and distribution of Hg in Plantago major L (typical specie from the study area) have been studied. The results showed that the total Hg concentrations in the soil ranged from 530 {+-} 32 mg kg{sup -}1 to 4300 {+-} 339 mg kg{sup -}1 even to 12378 {+-} 1051mg kg{sup -}1. It is in accordance with the normal values measured in a Hg mining area. Otherwise, the percentage of soluble Hg in soil with respect to the total Hg concentration is low (< 0.3 %) although if concentration instead of percentage is taking into account, the soluble Hg reached values up to 1.33 {+-}0.14 mg kg{sup -}1 that could mean a potential risk of pollution of groundwater by leaching process. Finally a brief description about different technologies for decreasing Hg concentration in the study soil, including phytoremediation, has been performed. (Author) 96 refs.

  18. 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.

  19. Impact of soil properties on critical concentrations of cadmium, lead, copper, zinc, and mercury in soil and soil solution in view of ecotoxicological effects.

    Science.gov (United States)

    de Vries, Wim; Lofts, Steve; Tipping, Ed; Meili, Markus; Groenenberg, Jan E; Schütze, Gudrun

    2007-01-01

    Risk assessment for metals in terrestrial ecosystems, including assessments of critical loads, requires appropriate critical limits for metal concentrations in soil and soil solution. This chapter presents an overview of methodologies used to derive critical (i) reactive and total metal concentrations in soils and (ii) free metal ion and total metal concentrations in soil solution for Cd, Pb, Cu, Zn, and Hg, taking into account the effect of soil properties related to ecotoxicological effects. Most emphasis is given to the derivation of critical free and total metal concentrations in soil solution, using available NOEC soil data and transfer functions relating solid-phase and dissolved metal concentrations. This approach is based on the assumption that impacts on test organisms (plants, microorganisms, and soil invertebrates) are mainly related to the soil solution concentration (activity) and not to the soil solid-phase content. Critical Cd, Pb, Cu, Zn, and Hg concentrations in soil solution vary with pH and DOC level. The results obtained are generally comparable to those derived for surface waters based on impacts to aquatic organisms. Critical soil metal concentrations, related to the derived soil solution limits, can be described as a function of pH and organic matter and clay content, and varying about one order of magnitude between different soil types.

  20. Redução do tempo de digestão na determinação de nitrogênio em solos Reduction of digestion time in the determination of total nitrogen in soils

    Directory of Open Access Journals (Sweden)

    Flávio Verlengia

    1968-01-01

    Full Text Available Foi estudada a redução do tempo de digestão na determinação do nitrogênio total em solos, assim como a perda dêsse nutriente durante a sua determinação. Procurou-se comparar o efeito de alguns catalisadores, como sulfato de cobre, óxido de mercúrio e selênio. Diversos tempos de ataques foram estudados, desde 10 até 960 minutos (16 horas. Verificou-se que as maiores reduções de tempo foram obtidas com o selênio, utilizado como catalisador, em presença de óxido de mercúrio, particularmente em solos onde o ataque se mostrou mais difícil. O catalisador tradicional - sulfato de cobre - foi o menos eficiente. A utilização do selênio, não provocou perda de nitrogênio durante a digestão.By using the Kjeldahl method in the determination of total nitrogen in soils, the effect of various catalysts related with digestion time and with possible nitrogen losses was studied. The experiment was carried out by using the catalysts CuSO4.5H2O; HgO and Se in six treatments. Results indicated that a pronounced reduction on digestion time was obtained by using selenium as catalyst. Best results, however, were obtained by using a mixture of selenium and mercury oxide, principally for soils of very difficult digestion (organic soil and "terra roxa" soil. In all treatments CuSO4.5H2O was the less efficient. Use of selenium did not cause loss of nitrogen.

  1. Application of neutron activation analysis to the determination of total mercury and other elements of interest in soil and sediment samples from Serra do Navio and Vila Nova River Basin, Amapa, Brazil; Aplicacao do metodo de ativacao neutronica a determinacao do mercurio total e outros elementos de interesse em amostras de solo e sedimento da Serra do Navio e Bacia do Rio Vila Nova, Amapa

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Cristina

    1997-07-01

    In this work it is presented a survey on total mercury determination by a radiochemical method in sediment and soil samples from two regions, in the state of Amapa: Serra do Navio (background area) and Vila Nova river basin (gold mining area). The method consisted in leaching of the irradiated samples with acqua regia in a Parr bomb, and heating in microwave oven, for one minute. Then the solvent extraction technique was applied, using bismuth diethyldithiocarbamate (Bi(DDC){sub 3}) as extractant agent. The organic phase, containing {sup 197}Hg and {sup 203}Hg radioisotopes, was measured in a gamma spectrometer with hyper pure Ge detector. This method eliminated the interference of the 279.54 keV photopeak of {sup 75}Se on 279.2 keV photopeak of {sup 203}Hg, besides improving counting statistics of both Hg radioisotopes. The elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, Ho, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, Ti, U, V, W, Yb, Zn and Zr were also determined by the instrumental neutron activation analysis. Two irradiation series were carried out to quantify these elements in soil and sediment samples; a short term irradiation allowed to evaluate Mg, Mn, Na, Ti and V levels, and by long term irradiation, the other elements were determined. Precision and accuracy of radiochemical procedure were verified by means of analysis of the reference materials Buffalo River Sediment and Lake Sediment, for sediments and GXR-5, for soils. For the instrumental analysis, the reference materials Buffalo River Sediment, Soil 7, JB-1 and Oyster Tissue were used. The samples were also submitted to X ray diffraction, in Instituto de Geoscience-USP, to observe mercury behaviour with mineralogy. Aluminium concentration was determined by X ray fluorescence method, in the Department of Materials, IPEN/CNEN-SP, making possible enrichment factor calculation so that mercurial contamination in the gold mining area (Vila Nova river basin) could be evaluated. The mercury

  2. 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.

  3. 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.

  4. Atmospheric mercury inputs in montane soils increase with elevation: evidence from mercury isotope signatures.

    Science.gov (United States)

    Zhang, Hua; Yin, Run-sheng; Feng, Xin-bin; Sommar, Jonas; Anderson, Christopher W N; Sapkota, Atindra; Fu, Xue-wu; Larssen, Thorjørn

    2013-11-25

    The influence of topography on the biogeochemical cycle of mercury (Hg) has received relatively little attention. Here, we report the measurement of Hg species and their corresponding isotope composition in soil sampled along an elevational gradient transect on Mt. Leigong in subtropical southwestern China. The data are used to explain orography-related effects on the fate and behaviour of Hg species in montane environments. The total- and methyl-Hg concentrations in topsoil samples show a positive correlation with elevation. However, a negative elevation dependence was observed in the mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) signatures of Hg isotopes. Both a MIF (Δ(199)Hg) binary mixing approach and the traditional inert element method indicate that the content of Hg derived from the atmosphere distinctly increases with altitude.

  5. 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

  6. Determination of the Proportion of Total Soil Extracellular Acid Phosphomonoesterase (E.C. 3.1.3.2 Activity Represented by Roots in the Soil of Different Forest Ecosystems

    Directory of Open Access Journals (Sweden)

    Klement Rejsek

    2012-01-01

    Full Text Available The aim of this study is to present a new method for determining the root-derived extracellular acid phosphomonoesterase (EAPM activity fraction within the total EAPM activity of soil. EAPM activity was determined for roots, organic and mineral soil. Samples were collected using paired PVC cylinders, inserted to a depth of 15 cm, within seven selected forest stands. Root-derived EAPM formed between 4 and18% of the total EAPM activity of soil from forests of differing maturity. A new approach, presented in this work, enables separation of root-derived EAPM activity from total soil EAPM. Separation of root-derived EAPM from soil provides a better understanding of its role in P-cycling in terrestrial ecosystems. The method presented in this work is a first step towards the separation of root- and microbe-derived EAPM in soils, which are thought to possess different kinetic properties and different sensitivity to environmental change.

  7. Distribution of total mercury and methylmercury around the small-scale gold mining area along the Cikaniki River, Bogor, Indonesia.

    Science.gov (United States)

    Tomiyasu, Takashi; Kodamatani, Hitoshi; Hamada, Yuriko Kono; Matsuyama, Akito; Imura, Ryusuke; Taniguchi, Yoko; Hidayati, Nuril; Rahajoe, Joeni Setijo

    2017-01-01

    This study investigates the distribution of total mercury (T-Hg) and methylmercury (MeHg) in the soil and water around the artisanal and small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia. The concentration of T-Hg and MeHg in the forest soil ranged from 0.07 to 16.7 mg kg -1 and from <0.07 to 2.0 μg kg -1 , respectively, whereas it ranged from 0.40 to 24.9 mg kg -1 and from <0.07 to 56.3 μg kg -1 , respectively, in the paddy field soil. In the vertical variation of the T-Hg of forest soil, the highest values were observed at the soil surface, and these values were found to decrease with increasing depth. A similar variation was observed for MeHg and total organic carbon content (TOC), and a linear relationship was observed between them. Mercury deposited on the soil surface can be trapped and retained by organic matter and subjected to methylation. The slope of the line obtained for the T-Hg vs. TOC plot became larger near the ASGM villages, implying a higher rate of mercury deposition in these areas. In contrast, the plots of MeHg vs. TOC fell along the same trend line regardless of the distance from the ASGM village. Organic carbon content may be a predominant factor in controlling MeHg formation in forest soils. The T-Hg concentration in the river water ranged from 0.40 to 9.6 μg L -1 . River water used for irrigation can prove to be a source of mercury for the paddy fields. The concentrations of Hg 0 and Hg 2+ in river water showed similar variations as that observed for the T-Hg concentration. The highest Hg 0 concentration of 3.2 μg L -1 can be attributed to the waste inflow from work sites. The presence of Hg 0 in river water can become a source of mercury present in the atmosphere along the river. MeHg concentration in the river water was found to be 0.004-0.14% of T-Hg concentration, which was considerably lower than the concentrations of other Hg species. However, MeHg comprised approximately 0.2% of the T-Hg

  8. The use of sensory perception indicators for improving the characterization and modelling of total petroleum hydrocarbon (TPH) grade in soils.

    Science.gov (United States)

    Roxo, Sónia; de Almeida, José António; Matias, Filipa Vieira; Mata-Lima, Herlander; Barbosa, Sofia

    2016-03-01

    This paper proposes a multistep approach for creating a 3D stochastic model of total petroleum hydrocarbon (TPH) grade in potentially polluted soils of a deactivated oil storage site by using chemical analysis results as primary or hard data and classes of sensory perception variables as secondary or soft data. First, the statistical relationship between the sensory perception variables (e.g. colour, odour and oil-water reaction) and TPH grade is analysed, after which the sensory perception variable exhibiting the highest correlation is selected (oil-water reaction in this case study). The probabilities of cells belonging to classes of oil-water reaction are then estimated for the entire soil volume using indicator kriging. Next, local histograms of TPH grade for each grid cell are computed, combining the probabilities of belonging to a specific sensory perception indicator class and conditional to the simulated values of TPH grade. Finally, simulated images of TPH grade are generated by using the P-field simulation algorithm, utilising the local histograms of TPH grade for each grid cell. The set of simulated TPH values allows several calculations to be performed, such as average values, local uncertainties and the probability of the TPH grade of the soil exceeding a specific threshold value.

  9. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale

    DEFF Research Database (Denmark)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing

    2016-01-01

    Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples...... scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced...... scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity....

  10. Profiles of traditional farms: soil texture, total inorganic N and bacteria-producing estate

    Directory of Open Access Journals (Sweden)

    Yuni Puji Hastuti

    2010-07-01

    Full Text Available Pond traditional system is the pond in still activity with a symple management system.  This activity indicated by low technology and relatively low production level.  Aquaculture activities in traditional pond not loss from nitrification and denitrification prosess, however this process is more low production rather than semiintensive and intensive system. This study aims to observe abundance of bacteria nitrification along with changes soil texture, and N-organic in the soil of traditional pond. Chemical and biological analyses were done using spectroscopy and Most Probable Number methods to determine the amount of nitrite and ammonium production of bacteria.  Based of the result, each stratum traditional ponds have relatively similar abundance in nitrite producing bacteria of 7.08-7.47 Log CFU/g.  Increasing abundance in ammonium producing bacteria was found in all stratum, range from 5.63 Log cfu/g to 8.12 Log cfu/g. From the first day of preparation, traditional ponds have a lot of nitrite and ammonium producing bacteria.Keywords: traditional, pond, nitrification, abundance of bacteri. ABSTRAKTambak sistem tradisional merupakan tambak yang dalam kegiatannya masih menggunakan sistem manajemen sederhana.  Hal ini ditandai dengan penerapan teknologi sederhana, dan tingkat produksi relatif rendah.  Kegiatan budidaya di tambak tradisional tidak akan terlepas dari proses nitrifikasi dan denitrifikasi, namun demikian proses ini relatif lebih rendah aktivitasnya daripada tambak sistem semiintensif dan intensif.  Tujuan dari penelitian ini adalah mempelajari kelimpahan bakteri penghasil senyawa nitrit, amonium seiring dengan perubahan tekstur tanah, dan N-organik pada tanah tambak tradisional. Media pertumbuhan bakteri dikondisikan bebas oksigen (oxygen free nitrogen/OFN method , sedangkan kelimpahan bakteri dianalisis dengan rumus most porbable number (MPN. Berdasarkan hasil, setiap strata tanah tambak tradisional memiliki jumlah bakteri

  11. 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...

  12. Evaluation of ethyl lactate as solvent in Fenton oxidation for the remediation of total petroleum hydrocarbon (TPH)-contaminated soil.

    Science.gov (United States)

    Jalilian Ahmadkalaei, Seyedeh Pegah; Gan, Suyin; Ng, Hoon Kiat; Abdul Talib, Suhaimi

    2017-07-01

    Due to the health and environmental risks posed by the presence of petroleum-contaminated areas around the world, remediation of petroleum-contaminated soil has drawn much attention from researchers. Combining Fenton reaction with a solvent has been proposed as a novel way to remediate contaminated soils. In this study, a green solvent, ethyl lactate (EL), has been used in conjunction with Fenton's reagents for the remediation of diesel-contaminated soil. The main aim of this research is to determine how the addition of EL affects Fenton reaction for the destruction of total petroleum hydrocarbons (TPHs) within the diesel range. Specifically, the effects of different parameters, including liquid phase volume-to-soil weight (L/S) ratio, hydrogen peroxide (H 2 O 2 ) concentration and EL% on the removal efficiency, have been studied in batch experiments. The results showed that an increase in H 2 O 2 resulted in an increase in removal efficiency of TPH from 68.41% at H 2 O 2  = 0.1 M to 90.21% at H 2 O 2  = 2 M. The lowest L/S, i.e. L/S = 1, had the highest TPH removal efficiency of 85.77%. An increase in EL% up to 10% increased the removal efficiency to 96.74% for TPH, and with further increase in EL%, the removal efficiency of TPH decreased to 89.6%. EL with an optimum value of 10% was found to be best for TPH removal in EL-based Fenton reaction. The power law and pseudo-first order equations fitted well to the experimental kinetic data of Fenton reactions.

  13. 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.

  14. Investigation of ratio 'strontium-calcium' in the plants and in the corresponding soil solution for 90Sr and for natural total strontium

    International Nuclear Information System (INIS)

    Prorok, V.V.; Makarenko, T.Yi.; Mel'nichenko, L.Yu.; Mason, K.F.V.; Ganushevich, A.P.; Ostashko, V.V.

    2005-01-01

    Ratios Sr/Ca for natural total strontium and 90 Sr/Ca in the plants and in the corresponding soil solutions for three experimental lands with 'fuel' type of pollution for several plants at natural conditions are determined. The lands with tree different types of soil are at the Exclusive Zone of the Chernobyl Power Station. The obtained experimental results shown that ratio Sr/Ca in plant is equal to this ratio in the corresponding soil solution for all investigated lands and plants. Ratio 90 Sr/Ca in plant exceeds this ratio at the corresponding soil solution

  15. Large Differences in Global and Regional Total Soil Carbon Stock Estimates Based on SoilGrids, HWSD, and NCSCD: Intercomparison and Evaluation Based on Field Data From USA, England, Wales, and France

    Science.gov (United States)

    Tifafi, Marwa; Guenet, Bertrand; Hatté, Christine

    2018-01-01

    Soils are the major component of the terrestrial ecosystem and the largest organic carbon reservoir on Earth. However, they are a nonrenewable natural resource and especially reactive to human disturbance and climate change. Despite its importance, soil carbon dynamics is an important source of uncertainty for future climate predictions and there is a growing need for more precise information to better understand the mechanisms controlling soil carbon dynamics and better constrain Earth system models. The aim of our work is to compare soil organic carbon stocks given by different global and regional databases that already exist. We calculated global and regional soil carbon stocks at 1 m depth given by three existing databases (SoilGrids, the Harmonized World Soil Database, and the Northern Circumpolar Soil Carbon Database). We observed that total stocks predicted by each product differ greatly: it is estimated to be around 3,400 Pg by SoilGrids and is about 2,500 Pg according to Harmonized World Soil Database. This difference is marked in particular for boreal regions where differences can be related to high disparities in soil organic carbon concentration. Differences in other regions are more limited and may be related to differences in bulk density estimates. Finally, evaluation of the three data sets versus ground truth data shows that (i) there is a significant difference in spatial patterns between ground truth data and compared data sets and that (ii) data sets underestimate by more than 40% the soil organic carbon stock compared to field data.

  16. Spatial Variation of Soil Organic Carbon and Total Nitrogen in the Coastal Area of Mid-Eastern China.

    Science.gov (United States)

    Xu, Yan; Pu, Lijie; Liao, Qilin; Zhu, Ming; Yu, Xue; Mao, Tianying; Xu, Chenxing

    2017-07-14

    Soils play an important role in sequestrating atmospheric CO₂. Coastal tidal flats have been intensively reclaimed for food security and living spaces worldwide. We aimed to identify the changes of soil organic carbon (SOC) and total nitrogen (TN) following coastal reclamation and their spatial variation in the coastal area of mid-Eastern China to provide information for coastal cropland management. We measured SOC and TN of 463 soil samples in the coastal plain of mid-Eastern China. The results showed that SOC and TN increased highly from the uncultivated coastal tidal flat (2.49 g·kg -1 and 0.21 g·kg -1 , respectively) to the cropland (10.73 g·kg -1 and 1.3 g·kg -1 , respectively). After long-term cultivation, SOC and TN in the old farmland (12.98 g·kg -1 and 1.49 g·kg -1 , respectively) were greater than those in the young farmland (5.76 g·kg -1 and 0.86 g·kg -1 , respectively). The density of SOC in the uncultivated coastal tidal flat, young farmland, and old farmland were 0.68 kg·C·m -2 , 1.52 kg·C·m -2 , and 3.31 kg·C·m -2 , respectively. The density of TN in the uncultivated coastal tidal flat, young farmland and old farmland were 0.05 kg·N·m -2 , 0.23 kg·N·m -2 , and 0.38 kg·N·m -2 , respectively. The C/N (11.17) in the uncultivated coastal tidal flat was highest comparing to that in the young and old farmland due to lower nitrogen. The C/N increased from 6.78 to 8.71 following cultivation. Reclaimed coastal tidal flats had high carbon and nitrogen sequestration potential that not only mitigated the threat of global warming, but also improved soil fertility for crop production. Coastal management of cropland should consider the spatial distribution of SOC and TN to improve ecosystem services of coastal soils.

  17. Quantitative Analysis of Total Petroleum Hydrocarbons in Soils: Comparison between Reflectance Spectroscopy and Solvent Extraction by 3 Certified Laboratories

    Directory of Open Access Journals (Sweden)

    Guy Schwartz

    2012-01-01

    Full Text Available The commonly used analytic method for assessing total petroleum hydrocarbons (TPH in soil, EPA method 418.1, is usually based on extraction with 1,1,2-trichlorotrifluoroethane (Freon 113 and FTIR spectroscopy of the extracted solvent. This method is widely used for initial site investigation, due to the relative low price per sample. It is known that the extraction efficiency varies depending on the extracting solvent and other sample properties. This study’s main goal was to evaluate reflectance spectroscopy as a tool for TPH assessment, as compared with three commercial certified laboratories using traditional methods. Large variations were found between the results of the three commercial laboratories, both internally (average deviation up to 20%, and between laboratories (average deviation up to 103%. Reflectance spectroscopy method was found be as good as the commercial laboratories in terms of accuracy and could be a viable field-screening tool that is rapid, environmental friendly, and cost effective.

  18. Soils

    Science.gov (United States)

    Emily Moghaddas; Ken Hubbert

    2014-01-01

    When managing for resilient forests, each soil’s inherent capacity to resist and recover from changes in soil function should be evaluated relative to the anticipated extent and duration of soil disturbance. Application of several key principles will help ensure healthy, resilient soils: (1) minimize physical disturbance using guidelines tailored to specific soil types...

  19. Determination of total arsenic in soil and arsenic-resistant bacteria from selected ground water in Kandal Province, Cambodia

    International Nuclear Information System (INIS)

    Hamzah, A.; Wong, K.K.; Hasan, F.N.; Mustafa, S.; Khoo, K.S.; Sarmani, S.B.

    2013-01-01

    Cambodia has geological environments conducive to generation of high-arsenic groundwater and people are at high risk of chronic arsenic exposure. The aims of this study are to investigate the concentration of total arsenic and to isolate and identify arsenic-resistant bacteria from selected locations in Kandal Province, Cambodia. The INAA technique was used to measure the concentration of total arsenic in soils. The arsenic concentrations in soils were above permissible 5 mg/kg, ranging from 5.34 to 27.81 mg/kg. Bacteria resistant to arsenic from two arsenic-contaminated wells in Preak Russey were isolated by enrichment method in nutrient broth (NB). Colonies isolated from NB was then grown on minimal salt media (MSM) added with arsenic at increasing concentrations of 10, 20, 30, 50, 100 and 250 ppm. Two isolates that can tolerate 750 ppm of arsenic were identified as Enterobacter agglomerans and Acinetobacter lwoffii based on a series of biochemical, physiological and morphological analysis. Optimum growth of both isolates ranged from pH 6.6 to 7.0 and 30-35 deg C. E. agglomerans and A. lwoffii were able to remove 66.4 and 64.1 % of arsenic, respectively at the initial concentration of 750 ppm, within 72 h of incubation. Using energy dispersive X-ray technique, the percentage of arsenic absorbed by E. agglomerans and A. lwoffii was 0.09 and 0.15 %, respectively. This study suggested that arsenic-resistant E. agglomerans and A. lwoffii removed arsenic from media due to their ability to absorb arsenic. (author)

  20. Quantification of Labile Soil Mercury by Stable Isotope Dilution Techniques

    Science.gov (United States)

    Shetaya, Waleed; Huang, Jen-How; Osterwalder, Stefan; Alewell, Christine

    2016-04-01

    been applied to estimate the labile pool of mercury in contaminated soils. We performed a series of soil incubations spiked with 196Hg2+aiming at measuring and modelling the progressive assimilation of Hg ions into less labile forms. Soils with a wide range of characteristics are taken for our research purpose, inclusive of Hg concentrations ranging from 0.1 to 390 mg kg-1, pH between 3.5 - 7.5 and total organic carbon (TOC) between 2.5 - 8 %. In parallel, the labile pool of Hg estimated using ID will be compared with that determined using conventional extraction methods, e.g. sequential extraction procedures. These altogether allows us to answer (1) how the E-value of Hg in soils is comparable to those estimated based on selective extraction methods, (2) how the labile Hg correlates with the total soil Hg, soil pH and TOC, and (3) how the solubility of added Hg (e.g. via rainfall) decreased in soils of different properties during aging. The obtained results fills the knowledge gap concerning Hg biogeochemistry in the terrestrial environment and serves as a basis for estimating (and predicting) the risk of soil Hg diffusion from a point source to the adjacent environments.

  1. Rate of uptake and distribution of Hg in dissolved organic carbon compounds in darkwater ecosystems by ICP-MS and enriched stable isotope spiking

    International Nuclear Information System (INIS)

    Telmer, Kevin; Dario Bermudez, Rafael; Veiga, Marcello M.; Souza, Terezinha Cid da

    2001-01-01

    The role of natural organic acids on mercury binding, transportation, net uptake rates and possibly net methylation rates will be evaluated by tracing these processes with isotope enriched mercury and ICP-MS technology. The correlation between dissolved organic matter and Hg in waters is well documented. It appears that organic acids can react with mercury residing in or emitted from different sources such as soils (particularly hydromorphic soils), laterites, natural degassing, forest fires, fuel combustion, gold mining activities, etc. to form soluble Hg-organo-complexes. The formation of these complexes is believed to greatly enhance Hg transport and be an important preliminary step in the formation of Methyl-Hg and biological uptake. The rates of these reactions and the key organic compounds involved in mercury binding will be determined by reacting isotopically-enriched Hg with samples containing a variety of concentrations and types of organic acids and subsequently analysing both reactants and organisms exposed to the reactants (bioassays) for Hg isotopes by ICP-MS. The Hg spike will allow the precise determination of rates of uptake and the most active agents of uptake. Initially, the method will be used to examine total Hg uptake and distribution but if technological limitations are overcome, this same approach can be used to determine net rates of methylation and net MeHg uptake. After the method is validated the experimental design can be altered to test the relative effects of such things as the addition of CO 2 (pH change), or adding a substrate such as Fe-Mn oxyhydroxides. The addition of synthetic materials such as mulched automobile tires, can also be tested with the goal developing a pragmatic remedial method for Hg containment. Ultimately, this research should contribute to an understanding of mercury mobilization, transport and bio-concentration mechanisms, and provide a basis for developing management and treatment strategies. Emphasis will be

  2. Avaliação da contaminação mercurial mediante análise do teor de Hg total em amostras de cabelo em comunidades ribeirinhas do Tapajós, Pará, Brasil

    Directory of Open Access Journals (Sweden)

    Pinheiro Maria da Conceição Nascimento

    2000-01-01

    Full Text Available Este estudo avalia a contaminação mercurial em comunidades de pescadores em quatro localidades nas margens do rio Tapajós: Rainha, Barreiras, São Luís do Tapajós e Paraná-Mirim. Análises toxocológicas das amostras de cabelo foram realizadas por espectofotometria de absorção atômica. Os níveis de mercúrio total em amostras de cabelo variaram entre 2,9µg/g e 71,5µg/g. Os valores mais baixos foram encontrados na comunidade de Paraná-Mirim. Os mais elevados, em São Luís do Tapajós e Barreiras, cerca de seis a sete vezes superiores ao valor estabelecido. As diferenças entre as concentrações médias de mercúrio total nas amostras, coletadas em populações ribeirinhas, a montante e a jusante do rio Tapajós em Itaituba, não apresentaram significância estatística (p > 0,05. Conclui-se que a exposição humana ao mercúrio por ingestão de peixes contaminados constitui risco potencial para o aparecimento de sintomas e sinais da doença de Minamata, o que recomenda a manutenção de um programa de vigilância epidemiológica.

  3. New technique for quantification of elemental hg in mine wastes and its implications for mercury evasion into the atmosphere

    Science.gov (United States)

    Jew, A.D.; Kim, C.S.; Rytuba, J.J.; Gustin, M.S.; Brown, Gordon E.

    2011-01-01

    Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline ??-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range. ?? 2011 American Chemical Society.

  4. Total and Bioaccessible Soil Arsenic and Lead Levels and Plant Uptake in Three Urban Community Gardens in Puerto Rico

    Science.gov (United States)

    Arsenic (As) and lead (Pb) are two contaminants of concern associated with urban gardening. In Puerto Rico, data currently is limited on As and Pb levels in urban garden soils, soil metal (loid) bioaccessibility, and uptake of As and Pb in soil by edible plants grown in the regio...

  5. A comparison of two colorimetric assays, based upon Lowry and Bradford techniques, to estimate total protein in soil extracts

    OpenAIRE

    Redmile-Gordon, M.A.; Armenise, E.; White, R.P.; Hirsch, P.R.; Goulding, K.W.T.

    2013-01-01

    Soil extracts usually contain large quantities of dissolved humified organic material, typically reflected by high polyphenolic content. Since polyphenols seriously confound quantification of extracted protein, minimising this interference is important to ensure measurements are representative. Although the Bradford colorimetric assay is used routinely in soil science for rapid quantification protein in soil-extracts, it has several limitations. We therefore investigated an alternative colori...

  6. Vertical distribution of soil extractable organic C and N contents and total C and N stocks in 78-year-old tree plantations in subtropical Australia.

    Science.gov (United States)

    Zhou, Xiaoqi; Dong, Haibo; Lan, Zhongming; Bacon, Gary; Hao, Yanbin; Chen, Chengrong

    2017-10-01

    Few studies have focused on the effects of long-term forest plantations on the soil profile of carbon (C) and nitrogen (N) stocks. In this study, we selected 78-year-old tree plantations that included three coniferous tree species (i.e., slash pine, hoop pine and kauri pine) and a Eucalyptus species in subtropical Australia. We measured soil extractable organic C (EOC) and N (EON) contents and total C and N stocks under different tree species on the forest floor and along a soil profile to 100 cm depth. The results showed that Eucalyptus had significantly higher soil EOC contents (3.3 Mg ha -1 ) than the other tree species (EOC of 1.9-2.3 Mg ha -1 ) and had significantly higher EON (156 kg ha -1 ) contents than slash pine (107 kg ha -1 ). Eucalyptus had significantly higher soil C (58.9 Mg ha -1 ) and N (2.03 Mg ha -1 ) stocks than the other tree species (22.3-27.6 Mg C ha -1 and 0.71-1.23 Mg N ha -1 ) at 0-100 cm depth. There were no differences in soil C stocks at the 0-100 cm depth among the coniferous tree species. Forest floor C stocks had stronger effects on mineral soil total N stocks than fine root biomass, whereas fine root biomass exerted stronger effects on soil total C stocks at the 0-100 cm depth than forest floor C and N stocks. Our results addressed large differences in soil C and N stocks under different tree species, which can provide useful information for local forest management practices in this region.

  7. 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.

  8. Effects of long-term Salix cultivation on total and plant-available contents of Cadmium in the soil - a pilot study

    International Nuclear Information System (INIS)

    Eriksson, Jan; Ledin, S.

    1996-02-01

    The aim of the project was to study how total and plant-available contents of Cadmium in the soil are affected by the large amounts of Cadmium that are removed during the harvesting of Salix. Eight long-term Salix plantations, 8-30 years old, were chosen. At each place soil samples were taken in 4 areas in the stands of Salix and in 4 neighbouring areas with comparable soil conditions, but without Salix (reference areas). Cd in three fractions of different bonding strength were determined in the soil samples. The fractions roughly correspond to the total concentration, the exchangeable fraction, and the fraction dissolved in the soil solution. The result showed a relatively minor effect of the Salix plantation on the total concentrations. In six of eight cases, however, the concentrations tended to be lower in the Salix plantations than in the reference areas. When consideration was given to certain pH differences, the exchangeable, and particularly the most soluble fraction, showed a clear tendency for concentrations to be lower in the Salix stands than in the reference areas.The concentrations in stem samples from growing stands were generally lower than those measured in harvest-mature stems in other studies. The concentrations in foliage were of the same magnitude as those in the stems, implying that there is an important return of Cd to the soil at leaf-fall. The negligible effect on the total content in the soil may depend on uptake occurring both in the topsoil and in the subsoil. Re-circulation via the leaves will also result in redistribution of Cd from the subsoil to the topsoil, compensating the uptake from the topsoil. The conclusion reached was that Salix cultivation results in a reduction of the plant-available Cd in the soil, but the effect is not concentrated to the topsoil. 13 refs, 5 tabs, 4 figs

  9. Data set on the effects of conifer control and slash burning on soil carbon, total N, organic matter and extractable micro-nutrients

    Directory of Open Access Journals (Sweden)

    Jonathan D. Bates

    2017-10-01

    Full Text Available Conifer control in sagebrush steppe of the western United States causes various levels of site disturbance influencing vegetation recovery and resource availability. The data set presented in this article include growing season availability of soil micronutrients and levels of total soil carbon, organic matter, and N spanning a six year period following western juniper (Juniperus occidentalis spp. occidentalis reduction by mechanical cutting and prescribed fire of western juniper woodlands in southeast Oregon. These data can be useful to further evaluate the impacts of conifer woodland reduction to soil resources in sagebrush steppe plant communities.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. Assessment of Non-Point Source Total Phosphorus Pollution from Different Land Use and Soil Types in a Mid-High Latitude Region of China

    Directory of Open Access Journals (Sweden)

    Zhiwei Wang

    2016-11-01

    Full Text Available The transport characteristics of phosphorus in soil and the assessment of its environmental risk have become hot topics in the environmental and agricultural fields. The Sanjiang Plain is an important grain production base in China, and it is characterised by serious land use change caused by large-scale agricultural exploitation. Agricultural inputs and tillage management have destroyed the soil nutrient balance formed over long-term conditions. There are few studies on non-point source phosphorus pollution in the Sanjiang Plain, which is the largest swampy low plain in a mid-high-latitude region in China. Most studies have focused on the water quality of rivers in marsh areas, or the export mechanism of phosphorus from specific land uses. They were conducted using experimental methods or empirical models, and need further development towards mechanism models and the macro-scale. The question is how to find a way to couple processes in phosphorus cycling and a distributed hydrological model considering local hydrological features. In this study, we report an attempt to use a distributed phosphorus transport model to analyse non-point source total phosphorus pollution from different land uses and soil types on the Sanjiang Plain. The total phosphorus concentration generally shows an annually increasing trend in the study area. The total phosphorus load intensity is heterogeneous in different land use types and different soil types. The average total phosphorus load intensity of different land use types can be ranked in descending order from paddy field, dry land, wetlands, grassland, and forestland. The average total phosphorus load intensity of different soil types can be ranked in descending order: paddy soil, bog soil, planosol, meadow soil, black soil, and dark brown earth. The dry land and paddy fields account for the majority of total phosphorus load in the study area. This is mainly caused by extensive use of phosphate fertilizer on the

  15. 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

  16. 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...

  17. 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...

  18. A preliminary study of the Hg flux from selected Ohio watersheds to Lake Erie

    International Nuclear Information System (INIS)

    Fitzgibbon, T.O.; Berry Lyons, W.; Gardner, Christopher B.; Carey, Anne E.

    2008-01-01

    New measurements of riverine dissolved and particulate Hg fluxes into Lake Erie from 12 northern Ohio watersheds have been determined from samples collected in April 2002 and analyzed using ultra-clean techniques with cold-vapor atomic fluorescence spectrometry. Total Hg concentrations ranged through 2.5-18.5 ng L -1 , with a mean of 10.4 ng L -1 with most Hg in particulate form. Dissolved Hg concentrations ranged through 0.8-4.3 ng L -1 , with a mean of 2.5 ng L -1 . Highest total Hg concentrations were observed in western rivers with primarily agricultural land use and eastern rivers with mixed land use in their watersheds. Total suspended solid concentrations ranged through 10-180 mg L -1 with particulate Hg concentrations ranging through 47-170 ng g -1 , with a mean of 99 ng g -1 . Particulate Hg was similar to published data for central Lake Erie bottom sediments but much lower than for bottom sediments in western Lake Erie. Total Hg concentrations were positively correlated with suspended sediment concentrations and negatively with dissolved NO 3 - concentrations. The total estimated annual Hg fluxes from these rivers into Lake Erie is estimated to be 85 kg, but because only one event was sampled during high flow conditions, this may be an overestimate. This is much lower than previous published estimates of riverine Hg input into Lake Erie

  19. 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...

  20. Dipole Bands in 196Hg

    International Nuclear Information System (INIS)

    Lawrie, J. J.; Lawrie, E. A.; Newman, R. T.; Sharpey-Schafer, J. F.; Smit, F. D.; Msezane, B.; Benatar, M.; Mabala, G. K.; Mutshena, K. P.; Federke, M.; Mullins, S. M.; Ncapayi, N. J.; Vymers, P.

    2011-01-01

    High spin states in 196 Hg have been populated in the 198 Pt(α,6n) reaction at 65 MeV and the level scheme has been extended. A new dipole band has been observed and a previously observed dipole has been confirmed. Excitation energies, spins and parities of these bands were determined from DCO ratio and linear polarization measurements. Possible quasiparticle excitations responsible for these structures are discussed.

  1. Dynamics of N-NH4 +, N-NO3 -, and total soil nitrogen in paddy field with azolla and biochar

    Science.gov (United States)

    Dewi, W. S.; Wahyuningsih, G. I.; Syamsiyah, J.; Mujiyo

    2018-03-01

    Nitrogen (N) is one of macronutrients which is dynamic in the soil and becomes constraint factor for rice crops. The addition of nitrogen fertilizers and its absorption in paddy field causes the dynamics of nitrogen, thus declines of N absorption efficiency. The aim of this research is to know influence Azolla, biochar and different varieties application on N-NH4 +, N-NO3 -, and total soil N in paddy field. This research was conducted in a screen house located in Jumantono Laboratory, Faculty of Agriculture, Universitas Sebelas Maret (UNS) with altitude 170 m asl from April to June 2016. Treatment factors that were examined consisted of azolla (0 and 10 tons/ha), biochar (0 and 2 tons/ha), and rice varieties (Cisadane, Memberamo, Ciherang, IR64). The results of this research showed that there was no interaction between azolla, biochar and varieties. Nevertheless, azolla treatment with dose of 10 tons/ha increased soil NH4 + content (41 days after planting, DAP) by 13.4% but tend to decrease at 70 and 90 DAP. Biochar treatment with dose of 2 ton/ha increases NO3 - soil content (70 DAP) by 1.7% but decreases total N soil by 5.8% (41 DAP) and 4.7% (90 DAP). Different rice varieties generated different soil NH4 + content (41 DAP) and rice root volume. Cisadane variety can increase soil NH4 + content (41 DAP) by 52.08% and root volume by 51.80% (90 DAP) compared with Ciherang variety. Organic rice field management with azolla and biochar affects the availability of N in the soil and increase N absorption efficiency through its role in increasing rice root volume.

  2. Total soil C and N sequestration in a grassland following 10 years of free air CO2 enrichment

    NARCIS (Netherlands)

    Kessel, van C.; Boots, B.; Graaff, de M.A.; Harris, D.; Blum, H.; Six, J.

    2006-01-01

    Soil C sequestration may mitigate rising levels of atmospheric CO2. However, it has yet to be determined whether net soil C sequestration occurs in N-rich grasslands exposed to long-term elevated CO2. This study examined whether N-fertilized grasslands exposed to elevated CO2 sequestered additional

  3. A distinct seasonal pattern of the ratio of soil respiration to total ecosystem respiration in a spruce-dominated forest

    Science.gov (United States)

    E.A. Davidson; A.D. Richardson; K.E. Savage; D.Y. Hollinger

    2006-01-01

    Annual budgets and fitted temperature response curves for soil respiration and ecosystem respiration provide useful information for partitioning annual carbon budgets of ecosystems, but they may not adequately reveal seasonal variation in the ratios of these two fluxes. Soil respiration (Rs) typically contributes 30-80% of...

  4. Assessment of total soil and plant trace elements in rice-based production systems in NE Italy

    Science.gov (United States)

    Bini, Claudio; Nadimi-Goki, Mandana; Kato, Yoichi; Vianello, Gilmo; Vittori, Livia; Wahsha, Mohammad; Spiandorello, Massimo

    2014-05-01

    Macro- and micronutrients concentrations, and PTEs contents in soils and plants (rice) from the rice district in the Venetian territory (NE Italy) have been determined by ICP-MS spectrometry, with the following aims: - to determine the background levels of macro- and microelements in the study area; - to assess possible contamination of soils and plants; - to calculate the Translocation Factor (TF) of metals from soil to plant, and the possible hazard for human health. Four rice plots with different rotation systems were investigated from seedling time to harvesting; sampling of soils (0-30cm) and plants was carried out 4 times during growing season (three replicates). Rice plants were separated into roots, stems, leaves and grains, and then oven-dried. Chemical and physical analyses were carried out at the Soil Science Lab of the University of Bologna and Venice, respectively. The results obtained point to a land with moderate soil contamination by trace elements (namely Li, Sn, Tl, Sr, Ti, Fe). Heavy metal (Sb, As, Be, Cd, Co, Cr, Ni, Pb, Cu, V, Zn ) concentrations in soils are below the threshold indicated by the Italian legislation (DM 152/2006). Cd, Sn, and Ti contents in soils are positively correlated with soil pH, while As, Fe, Li, Ti, Tl and Zn are negatively correlated with organic matter content. With the exception of Strontium, soil metal contents are always correlated between variable couples. HMs in plants vary according to the sampling season, texture and moisture, and soil pH. Most non-essential trace elements are accumulated in rice roots and, only in cases of essential micronutrients, in leaves. Therefore, rice can be assumed as an accumulator plant of As, Pb, Cr, Ba, and Ti, whereas it is as an indicator plant for Cu, Fe, Ni, Mn and Zn. The results of multiple linear regression analysis showed that soil pH has a larger effect on Ba, Cr, Cu, Fe, Mn, Ni, Ti and Zn concentrations in grain than other soil parameters. The average translocation of

  5. 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.

  6. A landscape-scale study of land use and parent material effects on soil organic carbon and total nitrogen in the Konya Basin, Turkey

    Science.gov (United States)

    Mayes, M. T.; Marin-Spiotta, E.; Ozdogan, M.; Erdogan, M. A.

    2011-12-01

    In ecosystems where intensive farming and grazing have been occurring for millennia, there is poor understanding of how present-day soil biogeochemical properties relate to factors associated with soil parent materials (e.g. texture, mineralogy), and the net effects of long-term land use practices. Soil organic carbon (SOC) and total soil nitrogen (TN) are important for their roles in maintaining soil structure, moisture, fertility and contributing to carbon sequestration. Our research used a state factor approach (Jenny 1981) to study effects of soil parent materials and land use practices on SOC, TN, and other properties across thirty-five sites in the Konya Basin, an arid region in south-central Turkey farmed and grazed for over 8,000 years. This project is one of the first to study land use impacts on soils at a landscape scale (500 km2) in south-central Turkey, and incorporate geospatial data (e.g. a satellite imagery-derived land cover map we developed) to aid selection of field sites. Focusing on the plough layer (0-25cm) in two depth intervals, we compared effects of agriculture, orchard cultivation and grazing land use practices and clay-loam alluvial, sandy-loam volcanic and lacustrine clay soils on soil properties using standard least squares regression analyses. SOC and TN depended strongly on parent materials, but not on land use. Averaged across both depth intervals, alluvial soil SOC and TN concentrations (19.4 ± 1.32 Mg/ha SOC, 2.86 ± 1.23 Mg/ha TN) were higher and significantly different than lacustrine (9.72 ± 3.01 Mg/ha SOC, 1.57 ± 0.69 Mg/ha TN) and volcanic soil concentrations (7.40 ± 1.72 Mg/ha SOC, 1.02 ± 0.35 Mg/ha TN). Land use significantly affected SOC and TN on alluvial soils, but not on volcanic or lacustrine soils. Our results demonstrate the potential for land use to have different effects on different soils in this region. Our data on SOC, TN and other soil properties illustrate patterns in regional SOC and TN variability not

  7. Long-term mercury dynamics in UK soils

    International Nuclear Information System (INIS)

    Tipping, E.; Wadsworth, R.A.; Norris, D.A.; Hall, J.R.; Ilyin, I.

    2011-01-01

    A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 μg Hg m -2 a -1 to rural soils, 19 μg Hg m -2 a -1 to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg 0 per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: → Spatial data for mercury in UK soils can be related to past atmospheric deposition. → The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. → UK soils currently contribute more Hg 0 to the atmosphere than human activities. → Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg 0 to the global circulation.

  8. Plant assemblage composition and soil P concentration differentially affect communities of AM and total fungi in a semi-arid grassland.

    Science.gov (United States)

    Klabi, Rim; Bell, Terrence H; Hamel, Chantal; Iwaasa, Alan; Schellenberg, Mike; Raies, Aly; St-Arnaud, Marc

    2015-01-01

    Adding inorganic P- and N-fixing legumes to semi-arid grasslands can increase forage yield, but soil nutrient concentrations and plant cover may also interact to modify soil fungal populations, impacting short- and long-term forage production. We tested the effect of plant assemblage (seven native grasses, seven native grasses + the domesticated N-fixing legume Medicago sativa, seven native grasses + the native N-fixing legume Dalea purpurea or the introduced grass Bromus biebersteinii + M. sativa) and soil P concentration (addition of 0 or 200 P2O5 kg ha(-1) at sowing) on the diversity and community structure of arbuscular mycorrhizal (AM) fungi and total fungi over two consecutive years, using 454-pyrosequencing of 18S rDNA and ITS amplicons. Treatment effects were stronger in the wet year (2008) than the dry year (2009). The presence of an N-fixing legume with native grasses generally increased AM fungal diversity, while the interaction between soil P concentration and plant assemblage modified total fungal community structure in 2008. Excluding interannual variations, which are likely driven by moisture and plant productivity, AM fungal communities in semi-arid grasslands appear to be primarily affected by plant assemblage composition, while the composition of other fungi is more closely linked to soil P. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Bioaccumulation of heavy metals in the earthworms Lumbricus rubellus and Aporrectodea caliginosa in relation to total and available metal concentrations in field soils

    International Nuclear Information System (INIS)

    Hobbelen, P.H.F.; Koolhaas, J.E.; Gestel, C.A.M. van

    2006-01-01

    The aim of this study was to determine important metal pools for bioaccumulation by the earthworms Lumbricus rubellus and Aporrectodea caliginosa in soils with high binding capacity. Cd, Cu and Zn concentrations in soil, pore water and CaCl 2 extracts of soil, in leaves of the plant species Urtica dioica and in earthworms were determined at 15 field sites constituting a gradient in metal pollution. Variations in the Cu and Cd concentrations in L. rubellus and Cu concentrations in A. caliginosa were best explained by total soil concentrations, while variation in Cd concentration in A. caliginosa was best explained by pore water concentrations. Zn concentrations in L. rubellus and A. caliginosa were not significantly correlated to any determined variable. It is concluded that despite low availability, earthworms in floodplain soils contain elevated concentrations of Cu and Cd, suggesting that uptake takes place not only from the soluble metal concentrations. - Earthworms in floodplain soils not only accumulate heavy metals from soluble metal pools

  10. Bioaccumulation of heavy metals in the earthworms Lumbricus rubellus and Aporrectodea caliginosa in relation to total and available metal concentrations in field soils

    Energy Technology Data Exchange (ETDEWEB)

    Hobbelen, P.H.F. [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)]. E-mail: phobbelen@usgs.gov; Koolhaas, J.E. [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Gestel, C.A.M. van [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

    2006-11-15

    The aim of this study was to determine important metal pools for bioaccumulation by the earthworms Lumbricus rubellus and Aporrectodea caliginosa in soils with high binding capacity. Cd, Cu and Zn concentrations in soil, pore water and CaCl{sub 2} extracts of soil, in leaves of the plant species Urtica dioica and in earthworms were determined at 15 field sites constituting a gradient in metal pollution. Variations in the Cu and Cd concentrations in L. rubellus and Cu concentrations in A. caliginosa were best explained by total soil concentrations, while variation in Cd concentration in A. caliginosa was best explained by pore water concentrations. Zn concentrations in L. rubellus and A. caliginosa were not significantly correlated to any determined variable. It is concluded that despite low availability, earthworms in floodplain soils contain elevated concentrations of Cu and Cd, suggesting that uptake takes place not only from the soluble metal concentrations. - Earthworms in floodplain soils not only accumulate heavy metals from soluble metal pools.

  11. Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils.

    Science.gov (United States)

    Figueiredo, Estela; Soares, M Elisa; Baptista, Paula; Castro, Marisa; Bastos, M Lourdes

    2007-08-22

    An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight

  12. 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

  13. Total and bioavailable arsenic concentration in arid soils and its uptake by native plants from the pre-Andean zones in Chile.

    Science.gov (United States)

    Díaz, O; Tapia, Y; Pastene, R; Montes, S; Núñez, N; Vélez, D; Montoro, R

    2011-06-01

    Arsenic is the most important contaminant of the environment in northern Chile. Soil samples and plant organs from three native plant species, Pluchea absinthioides, Atriplex atacamensis and Lupinus microcarpus, were collected from arid zones in order to determine the total and bioavailable arsenic concentrations in soils and to assess the bioconcentration factor (BCF) and transport index (Ti) of arsenic in the plants. Total arsenic concentrations in soils (pH 8.3-8.5) where A. atacamensis and P. absinthioides were collected, reached levels considered to be contaminated (54.3 ± 15.4 and 52.9 ± 9.9 mg kg⁻¹, respectively), and these values were approximately ten times higher than in soils (pH 7.6) where L. microcarpus was collected. Bioavailable arsenic ranged from 0.18 to 0.42% of total arsenic concentration. In the three plant species, arsenic concentration in leaves were significantly (p ≤ 0.05) higher than in roots. L. microcarpus showed the highest arsenic concentration in its leaves (9.7 ± 1.6 mg kg⁻¹) and higher values of BCF (1.8) and Ti (6.1), indicating that this species has a greater capacity to accumulate and translocate the metalloid to the leaf than do the other species.

  14. Parametrization consequences of constraining soil organic matter models by total carbon and radiocarbon using long-term field data

    Science.gov (United States)

    Menichetti, Lorenzo; Kätterer, Thomas; Leifeld, Jens

    2016-05-01

    Soil organic carbon (SOC) dynamics result from different interacting processes and controls on spatial scales from sub-aggregate to pedon to the whole ecosystem. These complex dynamics are translated into models as abundant degrees of freedom. This high number of not directly measurable variables and, on the other hand, very limited data at disposal result in equifinality and parameter uncertainty. Carbon radioisotope measurements are a proxy for SOC age both at annual to decadal (bomb peak based) and centennial to millennial timescales (radio decay based), and thus can be used in addition to total organic C for constraining SOC models. By considering this additional information, uncertainties in model structure and parameters may be reduced. To test this hypothesis we studied SOC dynamics and their defining kinetic parameters in the Zürich Organic Fertilization Experiment (ZOFE) experiment, a > 60-year-old controlled cropland experiment in Switzerland, by utilizing SOC and SO14C time series. To represent different processes we applied five model structures, all stemming from a simple mother model (Introductory Carbon Balance Model - ICBM): (I) two decomposing pools, (II) an inert pool added, (III) three decomposing pools, (IV) two decomposing pools with a substrate control feedback on decomposition, (V) as IV but with also an inert pool. These structures were extended to explicitly represent total SOC and 14C pools. The use of different model structures allowed us to explore model structural uncertainty and the impact of 14C on kinetic parameters. We considered parameter uncertainty by calibrating in a formal Bayesian framework. By varying the relative importance of total SOC and SO14C data in the calibration, we could quantify the effect of the information from these two data streams on estimated model parameters. The weighing of the two data streams was crucial for determining model outcomes, and we suggest including it in future modeling efforts whenever SO14C

  15. Reduction of soil erosion and mercury losses in agroforestry systems compared to forests and cultivated fields in the Brazilian Amazon.

    Science.gov (United States)

    Béliveau, Annie; Lucotte, Marc; Davidson, Robert; Paquet, Serge; Mertens, Frédéric; Passos, Carlos J; Romana, Christine A

    2017-12-01

    In addition to causing physical degradation and nutrient depletion, erosion of cultivated soils in the Amazon affects aquatic ecosystems through the release of natural soil mercury (Hg) towards lakes and rivers. While traditional agriculture is generally cited as being among the main causes of soil erosion, agroforestry practices are increasingly appreciated for soil conservation. This study was carried out in family farms of the rural Tapajós region (Brazil) and aimed at evaluating soil erosion and associated Hg release for three land uses. Soils, runoff water and eroded sediments were collected at three sites representing a land cover gradient: a recently burnt short-cycle cropping system (SCC), a 2-year-old agroforestry system (AFS) and a mature forest (F). At each site, two PVC soil erosion plots (each composed of three 2 × 5 m isolated subplots) were implemented on steep and moderate slopes respectively. Sampling was done after each of the 20 rain events that occurred during a 1-month study period, in the peak of the 2011 rain season. Runoff volume and rate, as well as eroded soil particles with their Hg and cation concentrations were determined. Total Hg and cation losses were then calculated for each subplot. Erosion processes were dominated by land use type over rainfall or soil slope. Eroded soil particles, as well as the amount of Hg and cations (CaMgK) mobilized at the AFS site were similar to those at the F site, but significantly lower than those at the SCC site (p agroforestry systems, even in their early stages of implementation, are characterized by low erosion levels resembling those of local forest environments, thus contributing to the maintenance of soil integrity and to the reduction of Hg and nutrient mobility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Variação do potencial total da água em uma toposseqüência de solos de tabuleiro, durante dois anos Total water potential variation in a soil table land topsequence, during two years

    Directory of Open Access Journals (Sweden)

    Luciano da Silva Souza

    2001-02-01

    Full Text Available O trabalho teve como objetivo avaliar quinzenalmente, em 1996 e 1997, a variação do potencial total da água ao longo do tempo, em solos de uma toposseqüência de tabuleiro localizada em Sapeaçu, BA. Esta toposseqüência tinha as seguintes características: a comprimento de 190 m; b declividade média de 0,097 m m-1; c cultivo com laranja; d Latossolo Amarelo argissólico coeso, no terço superior; e Argissolo Amarelo coeso, no terço médio; f Argissolo Acinzentado não coeso, no terço inferior. A umidade do solo foi medida com sonda de nêutrons, nas profundidades de 0,30, 0,70, 1,10 e 1,50 m. Com base nas respectivas curvas de retenção, obteve-se o potencial matricial e, em seguida, o potencial total da água, para cada solo, profundidade e tempo. A camada coesa dificulta o fluxo de água no solo, tanto no processo de molhamento como no de secamento. Em conseqüência, o potencial total da água em solos com camada coesa varia bruscamente na camada mais superficial, ao longo do tempo, e mais lentamente nas camadas mais profundas. Em solo não coeso, a variação brusca do potencial ocorre apenas na camada mais superficial. O limite de tensão de água no solo de -1.500 kPa como sendo o ponto de murchamento permanente não se aplica à cultura dos citros.The objective of this work was to evaluate, fortnightly, during 1996/1997, the total soil water potential variation in a tableland topsequence in Sapeaçu county, BA, Brazil. This topsequence had the following characteristics: a length of 190 m; b slope of 0.097 m m-1; c orange as growing crop; d the upper third with a cohesive argisolic Yellow Latosol; e the middle third with a cohesive Yellow Argisol; and f the lower third with a non-cohesive Gray Argisol. Soil water was estimated by neutron probe at depths of0.30, 0.70, 1.10, and 1.50 m. Based on water retention curves, matric potential and, in sequence, total soil water potential were determined, for each soil and depth in

  17. Storage and stability of biochar-derived carbon and total organic carbon in relation to minerals in an acid forest soil of the Spanish Atlantic area.

    Science.gov (United States)

    Fernández-Ugalde, Oihane; Gartzia-Bengoetxea, Nahia; Arostegi, Javier; Moragues, Lur; Arias-González, Ander

    2017-06-01

    Biochar can largely contribute to enhance organic carbon (OC) stocks in soil and improve soil quality in forest and agricultural lands. Its contribution depends on its recalcitrance, but also on its interactions with minerals and other organic compounds in soil. Thus, it is important to study the link between minerals, natural organic matter and biochar in soil. In this study, we investigated the incorporation of biochar-derived carbon (biochar-C) into various particle-size fractions with contrasting mineralogy and the effect of biochar on the storage of total OC in the particle-size fractions in an acid loamy soil under Pinus radiata (C3 type) in the Spanish Atlantic area. We compared plots amended with biochar produced from Miscanthus sp. (C4 type) with control plots (not amended). We separated sand-, silt-, and clay-size fractions in samples collected from 0 to 20-cm depth. In each fraction, we analyzed clay minerals, metallic oxides and oxy-hydroxides, total OC and biochar-C. The results showed that 51% of the biochar-C was in fractions fractions (0.2-2μm, 0.05-0.2μm, fractions, as it occurred with the vermiculitic phases and metallic oxides and oxy-hydroxides. Biochar also affected to the distribution of total OC among particle-size fractions. Total OC concentration was greater in fractions 2-20μm, 0.2-2μm, 0.05-0.2μm in biochar-amended plots than in control plots. This may be explained by the adsorption of dissolved OC from fraction organic matter already occurred in the first year. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Mercury emissions from flooded soils and sediments in Germany are an underestimated problem: challenges for reliable risk assessments and management strategies

    Directory of Open Access Journals (Sweden)

    Rinklebe J.

    2013-04-01

    Full Text Available Environmental pollution by mercury is a world-wide problem. Particularly floodplain ecosystems are frequently affected. One example is the Elbe River in Germany and its catchment areas; large amounts of Hg from a range of anthropogenic and geogenic sources have been accumulated in the soils of these floodplains. They serve as sink for Hg originating from the surface water of adjacent river. Today, the vastly elevated Hg contents of the floodplain soils at the Elbe River often exceed even the action values of the German Soil Conservation Law. This is especially important as Hg polluted areas at the Elbe River achieve several hundred square kilometres. Thus, authorities are coerced by law to conduct an appropriate risk assessment and to implement practical actions to eliminate or reduce environmental problems. A reliable risk assessment particularly with view to organisms (vegetation as green fodder and hay production, grazing and wild animals to avoid the transfer of Hg into the human food chain, requires an authentic determination of Hg fluxes and their dynamics since gaseous emissions from soil to atmosphere are an important pathway of Hg. However, reliable estimates of Hg fluxes from the highly polluted floodplain soils at the Elbe River and its tributaries, and its influencing factors are scarce. For this purpose, we have developed a new method to determine mercury emissions from soils at various sites. Our objectives were i to quantify seasonal variations of total gaseous mercury (TGM fluxes for floodplain soils at the Elbe River, ii to provide insights into physico-chemical processes regulating these TGM fluxes, and iii to quantify the impacts of the controlling factors soil temperature and soil water content on Hg volatilization from a typical contaminated floodplain soil within soil microcosm experiments under various controlled temperature and moisture conditions. Our study provides insight into TGM emissions from highly Hg

  19. Soils

    International Nuclear Information System (INIS)

    Freudenschuss, A.; Huber, S.; Riss, A.; Schwarz, S.; Tulipan, M.

    2001-01-01

    For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

  20. Bioavailability and soil-to-crop transfer of heavy metals in farmland soils: A case study in the Pearl River Delta, South China.

    Science.gov (United States)

    Zhang, Jingru; Li, Huizhen; Zhou, Yongzhang; Dou, Lei; Cai, Limei; Mo, Liping; You, Jing

    2018-04-01

    Soil-bound heavy metals are of great concern for human health due to the potential exposure via food chain transfer. In the present study, the occurrence, the bioavailability and the soil-to-crop transfer of heavy metals in farmland soils were investigated based on data from two agricultural areas, i.e. Sihui and Shunde in South China. Six heavy metals (As, Cu, Hg, Mn, Ni and Pb) were quantified in the farmland soils. The mean single pollution level indices (PI) were all lower than 1 except for Hg in soils from Shunde (PI = 1.51 ± 0.46), suggesting the farmland soils were within clean and slightly polluted by heavy metals. As, Cu, Ni and Pb were found to be mostly present in the non-bioavailable form. The majority of Hg was considered potentially bioavailable, and Mn was found to be largely bioavailable. Soil pH was an important factor influencing bioavailability of soil-bound heavy metals. The concentrations of heavy metals in vegetables from Sihui and Shunde were within the food hygiene standards, while the rice grain from Sihui was polluted by Pb (PI = 10.3 ± 23.4). Total soil concentrations of heavy metals were not correlated to their corresponding crop concentrations, instead, significant correlations were observed for bioavailable concentrations in soil. The results supported the notion that the bioavailability of the investigated heavy metals in the soil was largely responsible for their crop uptake. The soil-to-crop transfer factors based on bioavailable concentrations suggested that Cu, As and Hg in soils of the study area had greater tendency to be accumulated in the vegetables than other heavy metals, calling for further human health assessment by consuming the contaminated crops. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effects of Moisture and Particle Size on Quantitative Determination of Total Organic Carbon (TOC) in Soils Using Near-Infrared Spectroscopy.

    Science.gov (United States)

    Tamburini, Elena; Vincenzi, Fabio; Costa, Stefania; Mantovi, Paolo; Pedrini, Paola; Castaldelli, Giuseppe

    2017-10-17

    Near-Infrared Spectroscopy is a cost-effective and environmentally friendly technique that could represent an alternative to conventional soil analysis methods, including total organic carbon (TOC). Soil fertility and quality are usually measured by traditional methods that involve the use of hazardous and strong chemicals. The effects of physical soil characteristics, such as moisture content and particle size, on spectral signals could be of great interest in order to understand and optimize prediction capability and set up a robust and reliable calibration model, with the future perspective of being applied in the field. Spectra of 46 soil samples were collected. Soil samples were divided into three data sets: unprocessed, only dried and dried, ground and sieved, in order to evaluate the effects of moisture and particle size on spectral signals. Both separate and combined normalization methods including standard normal variate (SNV), multiplicative scatter correction (MSC) and normalization by closure (NCL), as well as smoothing using first and second derivatives (DV1 and DV2), were applied to a total of seven cases. Pretreatments for model optimization were designed and compared for each data set. The best combination of pretreatments was achieved by applying SNV and DV2 on partial least squares (PLS) modelling. There were no significant differences between the predictions using the three different data sets ( p TOC was carried out on 16 unknown soil samples to evaluate the predictive ability of the final combined calibration model. Hence, we demonstrate that sample preprocessing has minor influence on the quality of near infrared spectroscopy (NIR) predictions, laying the ground for a direct and fast in situ application of the method. Data can be acquired outside the laboratory since the method is simple and does not need more than a simple band ratio of the spectra.

  2. A comparison of two colorimetric assays, based upon Lowry and Bradford techniques, to estimate total protein in soil extracts.

    Science.gov (United States)

    Redmile-Gordon, M A; Armenise, E; White, R P; Hirsch, P R; Goulding, K W T

    2013-12-01

    Soil extracts usually contain large quantities of dissolved humified organic material, typically reflected by high polyphenolic content. Since polyphenols seriously confound quantification of extracted protein, minimising this interference is important to ensure measurements are representative. Although the Bradford colorimetric assay is used routinely in soil science for rapid quantification protein in soil-extracts, it has several limitations. We therefore investigated an alternative colorimetric technique based on the Lowry assay (frequently used to measure protein and humic substances as distinct pools in microbial biofilms). The accuracies of both the Bradford assay and a modified Lowry microplate method were compared in factorial combination. Protein was quantified in soil-extracts (extracted with citrate), including standard additions of model protein (BSA) and polyphenol (Sigma H1675-2). Using the Lowry microplate assay described, no interfering effects of citrate were detected even with concentrations up to 5 times greater than are typically used to extract soil protein. Moreover, the Bradford assay was found to be highly susceptible to two simultaneous and confounding artefacts: 1) the colour development due to added protein was greatly inhibited by polyphenol concentration, and 2) substantial colour development was caused directly by the polyphenol addition. In contrast, the Lowry method enabled distinction between colour development from protein and non-protein origin, providing a more accurate quantitative analysis. These results suggest that the modified-Lowry method is a more suitable measure of extract protein (defined by standard equivalents) because it is less confounded by the high polyphenolic content which is so typical of soil extracts.

  3. 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.

  4. Total content and bioavailability of plant essential nutrients and heavy metals in top-soils of an industrialized area of Northwestern Greece

    Science.gov (United States)

    Barouchas, Pantelis; Avramidis, Pavlos; Salachas, Georgios; Koulopoulos, Athanasios; Christodoulopoulou, Kyriaki; Liopa-Tsakalidi, Aglaia

    2017-04-01

    Thirty surface soil samples from northwestern Greece in the Ptolemais-Kozani basin, were collected and analyzed for their total content in thirteen elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Cd, Cr, Cu, Ni, Pb, Zn) by ICP-AES and bioavailable content from a plant nutrition scope of view for (Ca, Fe, K, Mg, Mn, Na, P, Zn) by AAS and colorimetric techniques. Particle size distribution, Cation Exchange Capacity (CEC) and the magnetic susceptibility, in a low and a high frequency (at 47kHz and 0.47kHz), of soil samples were measured also in order to correlate the results. Total carbonates were tested by the pressure technique (BD Inventions, FOGII digital soil calcimeter). The concentrations of these elements were compared with international standards and guidelines. The results indicated that Cu, Cd, Zn and Pb are found enriched in the top soils of the study area, mainly as a consequence of natural processes from the surrounding rocks. Moreover, the bioavailability of some of these elements with a plant nutrition interest was tested and results indicate that they do not pose an immediate threat to the environment or crops as it all demonstrated values in an adequate range. Magnetic susceptibility in low and high frequency was correlated with clay content.

  5. The potential for portable X-ray fluorescence determination of soil copper at ancient metallurgy sites, and considerations beyond measurements of total concentrations.

    Science.gov (United States)

    Tighe, M; Rogan, G; Wilson, S C; Grave, P; Kealhofer, L; Yukongdi, P

    2018-01-15

    Copper (Cu) at ancient metallurgy sites represents the earliest instance of anthropogenically generated metal pollution. Such sites are spread across a wide range of environments from Eurasia to South America, and provide a unique opportunity to investigate the past and present extent and impact of metalworking contamination. Establishing the concentration and extent of soil Cu at archaeometallurgy sites can enhance archaeological interpretations of site use but can also, more fundamentally, provide an initial indication of contamination risk from such sites. Systematic evaluations of total soil Cu concentrations at ancient metalworking sites have not been conducted, due in part to the limitations of conventional laboratory-based protocols. In this paper, we first review what is known about Cu soil concentrations at ancient metallurgy sites. We then assess the benefits and challenges of portable X-ray fluorescence spectrometry (pXRF) as an alternative, rapid technique for the assessment of background and contaminant levels of Cu in soils. We conclude that pXRF is an effective tool for identifying potential contamination. Finally, we provide an overview of some major considerations beyond total Cu concentrations, such as bioavailability assessments, that will need to be considered at such sites to move toward a complete assessment of environmental and human risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. 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.

  7. Effects of compost amended lead-arsenate contaminated soils on total and inorganic arsenic concentration in rice

    Science.gov (United States)

    Rice (Oryza sativa L.), a staple crop for over fifty percent of the world’s population, is also a source of dietary arsenic because of its efficiency at accumulating As. Pesticides containing As were once widely used in agriculture, and some soils in which these pesticides were used are now being u...

  8. 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.

  9. 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.

  10. 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.

  11. Effect of soil properties, heavy metals and emerging contaminants in the soil nematodes diversity.

    Science.gov (United States)

    Gutiérrez, Carmen; Fernández, Carlos; Escuer, Miguel; Campos-Herrera, Raquel; Beltrán Rodríguez, Mª Eulalia; Carbonell, Gregoria; Rodríguez Martín, Jose Antonio

    2016-06-01

    Among soil organisms, nematodes are seen as the most promising candidates for bioindications of soil health. We hypothesized that the soil nematode community structure would differ in three land use areas (agricultural, forest and industrial soils), be modulated by soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.), and strongly affected by high levels of heavy metals (Cd, Pb, Zn, Cr, Ni, Cu, and Hg) and emerging contaminants (pharmaceuticals and personal care products, PPCPs). Although these pollutants did not significantly affect the total number of free-living nematodes, diversity and structure community indices vastly altered. Our data showed that whereas nematodes with r-strategy were tolerant, genera with k-strategy were negatively affected by the selected pollutants. These effects diminished in soils with high levels of heavy metals given their adaptation to the historical pollution in this area, but not to emerging pollutants like PPCPs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Biochemical characteristics of a free cyanide and total nitrogen assimilating Fusarium oxysporum EKT01/02 isolate from cyanide contaminated soil

    OpenAIRE

    Akinpelu, Enoch A.; Adetunji, Adewole T.; Ntwampe, Seteno K.O.; Nchu, Felix; Mekuto, Lukhanyo

    2017-01-01

    Sustainability of nutrient requirements for microbial proliferation on a large scale is a challenge in bioremediation processes. This article presents data on biochemical properties of a free cyanide resistant and total nitrogen assimilating fungal isolate from the rhizosphere of Zea mays (maize) growing in soil contaminated with a cyanide-based pesticide. DNA extracted from this isolate were PCR amplified using universal primers; TEF1-α and ITS. The raw sequence files are available on the NC...

  13. A laboratory based experimental study of mercury emission from contaminated soils in the River Idrijca catchment

    Directory of Open Access Journals (Sweden)

    D. Kocman

    2010-02-01

    Full Text Available Results obtained by a laboratory flux measurement system (LFMS focused on investigating the kinetics of the mercury emission flux (MEF from contaminated soils of the Idrija Hg-mine region, Slovenia are presented. Representative soil samples with respect to total Hg concentrations (4–417 μg g−1 and land cover (forest, meadow and alluvial soil alongside the River Idrijca were analysed to determine the variation in MEF versus distance from the source, regulating three major environmental parameters comprising soil temperature, soil moisture and solar radiation. MEFs ranged from less than 2 to 530 ng m−2 h−1, with the highest emissions from contaminated alluvial soils and soils near the mining district in the town of Idrija. A significant decrease of MEF was then observed with increasing distance from these sites. The results revealed a strong positive effect of all three parameters investigated on momentum MEF. The light-induced flux was shown to be independent of the soil temperature, while the soil aqueous phase seems to be responsible for recharging the pool of mercury in the soil available for both the light- and thermally-induced flux. The overall flux response to simulated environmental conditions depends greatly on the form of Hg in the soil. Higher activation energies are required for the overall process to occur in soils where insoluble cinnabar prevails compared to soils where more mobile Hg forms and forms available for transformation processes are dominant.

  14. Spatial pattern of soil organic carbon and total nitrogen, and analysis of related factors in an agro-pastoral zone in Northern China

    Science.gov (United States)

    Wang, Xuyang; Chen, Yinping; Lian, Jie; Luo, Yongqing; Niu, Yayi; Gong, Xiangwen

    2018-01-01

    The spatial pattern of soil organic carbon (SOC) and total nitrogen (TN) densities plays a profound important role in estimating carbon and nitrogen budgets. Naiman Banner located in northern China was chosen as research site, a total of 332 soil samples were taken in a depth of 100 cm from the low hilly land in the southern part, sandy land in the middle part and an alluvial plain in the northern part of the county. The results showed that SOC and TN density initially decreased and then increased from the north to the south, The highest densities, were generally in the south, with the lowest generally in the middle part. The SOC and TN densities in cropland were significantly greater than those in woodland and grassland in the alluvial plains and for Naiman as a whole. The woodland SOC and TN density were higher than those of grassland in the low hilly land, and higher densities of SOC and TN in grassland than woodland in the sandy land and low hilly land. There were significant differences in SOC and TN densities among the five soil types of Cambisols, Arenosols, Gleysols, Argosols, and Kastanozems. In addition, SOC and TN contents generally decreased with increasing soil depth, but increased below a depth of 40 cm in the Cambisols and became roughly constant at this depth in the Kastanozems. There is considerable potential to sequester carbon and nitrogen in the soil via the conversion of degraded sandy land into woodland and grassland in alluvial plain, and more grassland should be established in sandy land and low hilly land. PMID:29771979

  15. Certification of a reference material for determination of total cyanide in soil to support implementation of the International Standard ISO 11262:2011.

    Science.gov (United States)

    Scharf, Holger; Bremser, Wolfram

    2015-04-01

    Cyanides are among the most important inorganic pollutants to be tested and monitored in environmental compartments. They can be distinguished and determined as free cyanide, weak acid dissociable cyanide or as total cyanide. However, in any case obtained, measurement results are operationally defined referring to the applied analytical method. In 2011, the International Standard ISO 11262 has been published which specifies a normative analytical method for the determination of total cyanide in soil. The objective of the project described in this paper was to provide the first soil reference material (CRM) certified for its mass fraction of total cyanide on the basis of this standard. A total of 12 German laboratories with proven experience in the determination of cyanides in environmental samples participated in the certification study. Measurement results were evaluated in full compliance with the requirements of ISO Guide 35. Taking into account the results of the inter-laboratory comparison as well as the outcome of the homogeneity and stability studies, a certified mass fraction of total cyanide of 21.1 mg/kg and an expanded uncertainty (k = 2) of 1.3 mg/kg were assigned to the material. The reference material has been issued as CRM BAM-U114.

  16. Seasonal variation and distribution of total and active microbial community of beta-glucosidase encoding genes in coniferous forest soil

    Czech Academy of Sciences Publication Activity Database

    Pathan, S.I.; Žifčáková, Lucia; Ceccherini, M.T.; Pantani, O.L.; Větrovský, Tomáš; Baldrian, Petr

    2017-01-01

    Roč. 105, February (2017), s. 71-80 ISSN 0038-0717 R&D Projects: GA ČR(CZ) GA16-08916S Grant - others:Transbiodiverse(CZ) 7. RP Marie Curie ITN FP7/2007e2013 project 289949 Institutional support: RVO:61388971 Keywords : Beta-Glucosidases * Forest soil * Bacteria Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.857, year: 2016

  17. 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.

  18. 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

  19. Changes in soil organic carbon and total nitrogen in croplands converted to walnut-based agroforestry systems and orchards in southeastern Loess Plateau of China.

    Science.gov (United States)

    Lu, Sen; Meng, Ping; Zhang, Jinsong; Yin, Changjun; Sun, Shiyou

    2015-11-01

    Limited information is available on the effects of agroforestry system practices on soil properties in the Loess Plateau of China. Over the last decade, a vegetation restoration project has been conducted in this area by converting cropland into tree-based agroforestry systems and orchards to combat soil erosion and degradation. The objective of the present study was to determine the effects of land use conversion on soil organic carbon and total nitrogen in southeastern Loess Plateau. The experiment included three treatments: walnut intercropping system (AF), walnut orchard (WO), and traditional cropland (CR). After 7 years of continual management, soil samples were collected at 0-10, 10-30, and 30-50-cm depths for three treatments, and soil organic carbon (SOC) and total nitrogen (TN) were measured. Results showed that compared with the CR and AF treatments, WO treatment decreased both SOC and TN concentrations in the 0-50-cm soil profile. However, similar patterns of SOC and TN concentrations were observed in the AF and CR treatments across the entire profile. The SOC stocks at 0-50-cm depth were 5.42, 5.52, and 4.67 kg m(-2) for CR, AF, and WO treatments, respectively. The calculated TN stocks at 0-50-cm depth were 0.63, 0.62, and 0.57 kg m(-2) for CR, AF, and WO treatments, respectively. This result demonstrated that the stocks of SOC and TN in WO were clearly lower than those of AF and CR and that the walnut-based agroforestry system was more beneficial than walnut monoculture in terms of SOC and TN sequestration. Owing to the short-term intercropping practice, the changes in SOC and TN stocks were slight in AF compared with those in CR. However, a significant decrease in SOC and TN stocks was observed during the conversion of cropland to walnut orchard after 7 years of management. We also found that land use types had no significant effect on soil C/N ratio. These findings demonstrated that intercropping between walnut rows can potentially maintain

  20. 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.

  1. ASSESSMENT OF THE TOTAL PETROLEUM HYDROCARBON CONTENT OF AGRICULTURAL SOIL POLLUTED WITH DIFFERENT VOLUME OF CRUDE OIL DURING PLANT- MICROBE INTERACTION

    Directory of Open Access Journals (Sweden)

    Toochukwu Ekwutosi OGBULIE

    2014-06-01

    Full Text Available The effectiveness of plants in interaction with indigenous organisms in environmental clean –up was evaluated. The agricultural soil used for the study was polluted with 100ml, 200ml, 400ml and 800ml of Bonny light crude oil [100%]. Pre and post Microbial examination of the polluted soil identified the indigenous flora present in the soil to be Penicillum sp Aspergillus fumigatus, Aspergillus niger, Candida sp, Pseudomonas fluorescence, Acinetobacter baumanni, Bacillus mycoides, Klebsiella sp., Staphylococcus aureus and Escherichia coli though the absence of S aureus and E. coli was evident during the latter. Vigna unguiculata var unguiculata, Mucuna pruriens, Zea mays and Telfairia occidentalis were the test plant used. Gas chromatographic (GC analysis revealed the total petroleum hydrocarbon (TPH of polluted soil on comparison with the value of 10,380 kg/ mg for control sample, to be low. The high TPH obtained from samples polluted with higher concentration depicts that the numbers of plants to be cultivated for remediation could be a determining factor for a faster clean-up. Statistical analysis using analysis of variance (ANOVA model of SPSS software however, showed there was no significant difference in the degradation of crude oil in samples that are in the green house or field.

  2. Time series models for prediction the total and dissolved heavy metals concentration in road runoff and soil solution of roadside embankments

    Science.gov (United States)

    Aljoumani, Basem; Kluge, Björn; sanchez, Josep; Wessolek, Gerd

    2017-04-01

    Highways and main roads are potential sources of contamination for the surrounding environment. High traffic rates result in elevated heavy metal concentrations in road runoff, soil and water seepage, which has attracted much attention in the recent past. Prediction of heavy metals transfer near the roadside into deeper soil layers are very important to prevent the groundwater pollution. This study was carried out on data of a number of lysimeters which were installed along the A115 highway (Germany) with a mean daily traffic of 90.000 vehicles per day. Three polyethylene (PE) lysimeters were installed at the A115 highway. They have the following dimensions: length 150 cm, width 100 cm, height 60 cm. The lysimeters were filled with different soil materials, which were recently used for embankment construction in Germany. With the obtained data, we will develop a time series analysis model to predict total and dissolved metal concentration in road runoff and in soil solution of the roadside embankments. The time series consisted of monthly measurements of heavy metals and was transformed to a stationary situation. Subsequently, the transformed data will be used to conduct analyses in the time domain in order to obtain the parameters of a seasonal autoregressive integrated moving average (ARIMA) model. Four phase approaches for identifying and fitting ARIMA models will be used: identification, parameter estimation, diagnostic checking, and forecasting. An automatic selection criterion, such as the Akaike information criterion, will use to enhance this flexible approach to model building

  3. Uptake of Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbons (PAHs) by Oryza sativa L. Grown in Soil Contaminated with Crude Oil.

    Science.gov (United States)

    Patowary, Rupshikha; Patowary, Kaustuvmani; Devi, Arundhuti; Kalita, Mohan Chandra; Deka, Suresh

    2017-01-01

    The purpose of this study was to determine whether total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbons (PAHs) present in crude oil contaminated sites are transferred to roots, shoots and finally the grains of rice crops (Oryza sativa L.) grown in those sites. Soil was artificially contaminated with crude oil at concentrations of 0, 1000, 5000, 10,000, and 15,000 mg/kg, followed by planting of rice seedlings. After harvest, TPH in plant samples were measured, and it was determined that the uptake of TPH by the plants gradually increased as the concentration of oil in soil increased. Further, from GC-MS analysis, it was observed that PAHs including naphthalene and phenanthrene bioaccumulated in rice plant parts. Vital physico-chemical properties of soil were also altered due to crude oil contamination. Our study revealed that rice plants grown in crude oil polluted sites can uptake TPH including PAHs, thus emphasising the importance of prior investigation of soil condition before cultivation of crops.

  4. 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.)

  5. Quantifying the effects of soil temperature, moisture and sterilization on elemental mercury formation in boreal soils.

    Science.gov (United States)

    Pannu, Ravinder; Siciliano, Steven D; O'Driscoll, Nelson J

    2014-10-01

    Soils are a source of elemental mercury (Hg(0)) to the atmosphere, however the effects of soil temperature and moisture on Hg(0) formation is not well defined. This research quantifies the effect of varying soil temperature (278-303 K), moisture (15-80% water filled pore space (WFPS)) and sterilization on the kinetics of Hg(0) formation in forested soils of Nova Scotia, Canada. Both, the logarithm of cumulative mass of Hg(0) formed in soils and the reduction rate constants (k values) increased with temperature and moisture respectively. Sterilizing soils significantly (p soils and our results highlight two key processes: (i) a fast abiotic process that peaks at 45% WFPS and depletes a small pool of Hg(0) and; (ii) a slower, rate limiting biotic process that generates a large pool of reducible Hg(II). Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. 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.

  7. Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for model calibration and validation in a large ungauged catchment

    DEFF Research Database (Denmark)

    Milzow, Christian; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

    2010-01-01

    The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration and validation of a rainfall-runoff model...... of the ungauged Okavango catchment in Southern Africa: (i) Surface soil moisture (SSM) estimates derived from SAR measurements onboard the Envisat satellite; (ii) Radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum width of about one...... hundred meters; and (iii) Temporal changes of the Earth’s gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE) caused by total water storage changes in the catchment. The SSM data are compared to simulated moisture conditions in the top soil layer. They cannot be used for model...

  8. [Storages and distributed patterns of soil organic carbon and total nitrogen during the succession of artificial sand-binding vegetation in arid desert ecosystem].

    Science.gov (United States)

    Jia, Xiao-Hong; Li, Xin-Rong; Zhou, Yu-Yan; Li, Yuan-Shou

    2012-03-01

    Soil carbon pool acts as the largest one of carbon pools in the terrestrial ecosystem. The storages and distributed patterns of soil organic carbon (SOC) and total nitrogen (TN) evaluated accurately are helpful to predict the feedback between the terrestrial ecosystem and climate changes. Based on the data about bulk density, content of SOC and TN at 0-100 cm soil profile, the density of SOC and TN at the temporal (chronosequence of artificial vegetation) and spatial (vertical) distributed patterns have been estimated. The results indicated that storages of SOC and TN at 0-100 cm depth increased with the chronosequence of artificial vegetation. The storages of SOC and TN showed the same tendency with the succession time of artificial vegetation. Storages of SOC and TN significantly increased at the early stage of banding sand by artificially vegetation ( 25 a). The variation of storages mainly occurred in the 0-20 cm depth. The storages decreased with the soil vertical depth. At the early stage of banding sand, increase in storage included every depth (0-100 cm). Whereas, at the later stage, increase in storage at 0-20 cm depth was main, and increase in the 20-100 cm was inconspicuous. The accumulation of storage at the shallow soil depth was more notability with the succession of artificial vegetation. The distributed pattern of storage in SOC and TN has been confirmed in arid desert regions below 200 mm annual precipitation. This was beneficial to understand the carbon cycle and to predict the feedback relationship between desert ecosystem and climate changes.

  9. Watershed and discharge influences on the phase distribution and tributary loading of total mercury and methylmercury into Lake Superior

    International Nuclear Information System (INIS)

    Babiarz, Christopher; Hoffmann, Stephen; Wieben, Ann; Hurley, James; Andren, Anders; Shafer, Martin; Armstrong, David

    2012-01-01

    Knowledge of the partitioning and sources of mercury are important to understanding the human impact on mercury levels in Lake Superior wildlife. Fluvial fluxes of total mercury (Hg T ) and methylmercury (MeHg) were compared to discharge and partitioning trends in 20 sub-basins having contrasting land uses and geological substrates. The annual tributary yield was correlated with watershed characteristics and scaled up to estimate the basin-wide loading. Tributaries with clay sediments and agricultural land use had the largest daily yields with maxima observed near the peak in water discharge. Roughly 42% of Hg T and 57% of MeHg was delivered in the colloidal phase. Tributary inputs, which are confined to near-shore zones of the lake, may be more important to the food-web than atmospheric sources. The annual basin-wide loading from tributaries was estimated to be 277 kg yr −1 Hg T and 3.4 kg yr −1 MeHg (5.5 and 0.07 mg km −2 d −1 , respectively). - Highlights: ► The highest mercury yields occurred during spring melt except in forested watersheds. ► Roughly half of the mercury yield occurred in the colloidal phase. ► About 277 kg of Hg T and 3.4 kg of MeHg were delivered annually via tributaries. ► Whole-water MeHg loading was roughly equivalent to the estimated atmospheric loading. ► Watersheds with peat, loam or sandy soils deliver more MeHg than those with clays. - Tributary inputs, which are confined to the near-shore zones of Lake Superior, provide more mercury to these sensitive aquatic habitats than direct atmospheric deposition.

  10. 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)

  11. Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

    Science.gov (United States)

    Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai

    2018-03-01

    We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5  g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. 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...

  13. 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.

  14. Biochemical characteristics of a free cyanide and total nitrogen assimilating Fusarium oxysporum EKT01/02 isolate from cyanide contaminated soil

    Directory of Open Access Journals (Sweden)

    Enoch A. Akinpelu

    2017-10-01

    Full Text Available Sustainability of nutrient requirements for microbial proliferation on a large scale is a challenge in bioremediation processes. This article presents data on biochemical properties of a free cyanide resistant and total nitrogen assimilating fungal isolate from the rhizosphere of Zea mays (maize growing in soil contaminated with a cyanide-based pesticide. DNA extracted from this isolate were PCR amplified using universal primers; TEF1-α and ITS. The raw sequence files are available on the NCBI database. Characterisation using biochemical data was obtained using colorimetric reagents analysed with VITEK® 2 software version 7.01. The data will be informative in selection of biocatalyst for environmental engineering application.

  15. Biochemical characteristics of a free cyanide and total nitrogen assimilating Fusarium oxysporum EKT01/02 isolate from cyanide contaminated soil.

    Science.gov (United States)

    Akinpelu, Enoch A; Adetunji, Adewole T; Ntwampe, Seteno K O; Nchu, Felix; Mekuto, Lukhanyo

    2017-10-01

    Sustainability of nutrient requirements for microbial proliferation on a large scale is a challenge in bioremediation processes. This article presents data on biochemical properties of a free cyanide resistant and total nitrogen assimilating fungal isolate from the rhizosphere of Zea mays (maize) growing in soil contaminated with a cyanide-based pesticide. DNA extracted from this isolate were PCR amplified using universal primers; TEF1-α and ITS. The raw sequence files are available on the NCBI database. Characterisation using biochemical data was obtained using colorimetric reagents analysed with VITEK ® 2 software version 7.01. The data will be informative in selection of biocatalyst for environmental engineering application.

  16. 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

  17. 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....

  18. Ecological Risk of Heavy Metals and a Metalloid in Agricultural Soils in Tarkwa, Ghana

    Science.gov (United States)

    Bortey-Sam, Nesta; Nakayama, Shouta M. M.; Akoto, Osei; Ikenaka, Yoshinori; Baidoo, Elvis; Mizukawa, Hazuki; Ishizuka, Mayumi

    2015-01-01

    Heavy metals and a metalloid in agricultural soils in 19 communities in Tarkwa were analyzed to assess the potential ecological risk. A total of 147 soil samples were collected in June, 2012 and analyzed for As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. Mean concentrations (mg/kg dw) of heavy metals in the communities decreased in order of Zn (39) ˃ Cr (21) ˃ Pb (7.2) ˃ Cu (6.2) ˃ As (4.4) ˃ Ni (3.7) ˃ Co (1.8) ˃ Hg (0.32) ˃ Cd (0.050). Correlations among heavy metals and soil properties indicated that soil organic matter could have substantial influence on the total contents of these metals in soil. From the results, integrated pollution (Cdeg) in some communities such as, Wangarakrom (11), Badukrom (13) and T–Tamso (17) indicated high pollution with toxic metals, especially from As and Hg. Potential ecological risk (RI) indices indicated low (Mile 7) to high risks (Wangarakrom; Badukrom) of metals. Based on pollution coefficient (Cif), Cdeg, monomial ecological risk (Eir) and RI, the investigated soils fall within low to high contamination and risk of heavy metals to the ecological system especially plants, soil invertebrates and/or mammalian wildlife. This represented moderate potential ecological risk in the study area, and mining activities have played a significant role. PMID:26378563

  19. Development, optimization, validation and application of faster gas chromatography - flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils.

    Science.gov (United States)

    Zubair, Abdulrazaq; Pappoe, Michael; James, Lesley A; Hawboldt, Kelly

    2015-12-18

    This paper presents an important new approach to improving the timeliness of Total Petroleum Hydrocarbon (TPH) analysis in the soil by Gas Chromatography - Flame Ionization Detector (GC-FID) using the CCME Canada-Wide Standard reference method. The Canada-Wide Standard (CWS) method is used for the analysis of petroleum hydrocarbon compounds across Canada. However, inter-laboratory application of this method for the analysis of TPH in the soil has often shown considerable variability in the results. This could be due, in part, to the different gas chromatography (GC) conditions, other steps involved in the method, as well as the soil properties. In addition, there are differences in the interpretation of the GC results, which impacts the determination of the effectiveness of remediation at hydrocarbon-contaminated sites. In this work, multivariate experimental design approach was used to develop and validate the analytical method for a faster quantitative analysis of TPH in (contaminated) soil. A fractional factorial design (fFD) was used to screen six factors to identify the most significant factors impacting the analysis. These factors included: injection volume (μL), injection temperature (°C), oven program (°C/min), detector temperature (°C), carrier gas flow rate (mL/min) and solvent ratio (v/v hexane/dichloromethane). The most important factors (carrier gas flow rate and oven program) were then optimized using a central composite response surface design. Robustness testing and validation of model compares favourably with the experimental results with percentage difference of 2.78% for the analysis time. This research successfully reduced the method's standard analytical time from 20 to 8min with all the carbon fractions eluting. The method was successfully applied for fast TPH analysis of Bunker C oil contaminated soil. A reduced analytical time would offer many benefits including an improved laboratory reporting times, and overall improved clean up

  20. Gaseous elemental mercury emissions and CO2 respiration rates in terrestrial soils under controlled aerobic and anaerobic laboratory conditions

    International Nuclear Information System (INIS)

    Obrist, Daniel; Fain, Xavier; Berger, Carsen

    2010-01-01

    Mercury (Hg) levels in terrestrial soils are linked to the presence of organic carbon (C). Carbon pools are highly dynamic and subject to mineralization processes, but little is known about the fate of Hg during decomposition. This study evaluated relationships between gaseous Hg emissions from soils and carbon dioxide (CO 2 ) respiration under controlled laboratory conditions to assess potential losses of Hg to the atmosphere during C mineralization. Results showed a linear correlation (r 2 = 0.49) between Hg and CO 2 emissions in 41 soil samples, an effect unlikely to be caused by temperature, radiation, different Hg contents, or soil moisture. Stoichiometric comparisons of Hg/C ratios of emissions and underlying soil substrates suggest that 3% of soil Hg was subject to evasion. Even minute emissions of Hg upon mineralization, however, may be important on a global scale given the large Hg pools sequestered in terrestrial soils and C stocks. We induced changes in CO 2 respiration rates and observed Hg flux responses, including inducement of anaerobic conditions by changing chamber air supply from N 2 /O 2 (80% and 20%, respectively) to pure N 2 . Unexpectedly, Hg emissions almost quadrupled after O 2 deprivation while oxidative mineralization (i.e., CO 2 emissions) was greatly reduced. This Hg flux response to anaerobic conditions was lacking when repeated with sterilized soils, possibly due to involvement of microbial reduction of Hg 2+ by anaerobes or indirect abiotic effects such as alterations in soil redox conditions. This study provides experimental evidence that Hg volatilization, and possibly Hg 2+ reduction, is related to O 2 availability in soils from two Sierra Nevada forests. If this result is confirmed in soils from other areas, the implication is that Hg volatilization from terrestrial soils is partially controlled by soil aeration and that low soil O 2 levels and possibly low soil redox potentials lead to increased Hg volatilization from soils.

  1. Hg isotopes reveal in-stream processing and legacy inputs in East Fork Poplar Creek, Oak Ridge, Tennessee, USA.

    Science.gov (United States)

    Demers, Jason D; Blum, Joel D; Brooks, Scott C; Donovan, Patrick M; Riscassi, Ami L; Miller, Carrie L; Zheng, Wang; Gu, Baohua

    2018-04-25

    Natural abundance stable Hg isotope measurements were used to place new constraints on sources, transport, and transformations of Hg along the flow path of East Fork Poplar Creek (EFPC), a point-source contaminated headwater stream in Oak Ridge, Tennessee. Particulate-bound Hg in the water column of EFPC within the Y-12 National Security Complex, was isotopically similar to average metallic Hg(0) used in industry, having a mean δ202Hg value of -0.42 ± 0.09‰ (1SD) and near-zero Δ199Hg. On average, particulate fraction δ202Hg values increased downstream by 0.53‰, while Δ199Hg decreased by -0.10‰, converging with the Hg isotopic composition of the fine fraction of streambed sediment along the 26 km flow path. The dissolved fraction behaved differently. Although initial Δ199Hg values of the dissolved fraction were also near-zero, these values increased transiently along the flow path. Initial δ202Hg values of the dissolved fraction were more variable than in the particulate fraction, ranging from -0.44 to 0.18‰ among three seasonal sampling campaigns, but converged to an average δ202Hg value of 0.01 ± 0.10‰ (1SD) downstream. Dissolved Hg in the hyporheic and riparian pore water had higher and lower δ202Hg values, respectively, compared to dissolved Hg in stream water. Variations in Hg isotopic composition of the dissolved and suspended fractions along the flow path suggest that: (1) physical processes such as dilution and sedimentation do not fully explain decreases in total mercury concentrations along the flow path; (2) in-stream processes include photochemical reduction, but microbial reduction is likely more dominant; and (3) additional sources of dissolved mercury inputs to EFPC at baseflow during this study predominantly arise from the hyporheic zone.

  2. Survival and death of the haloarchaeon Natronorubrum strain HG-1 in a simulated martian environment

    Science.gov (United States)

    Peeters, Z.; Vos, D.; ten Kate, I. L.; Selch, F.; van Sluis, C. A.; Sorokin, D. Yu.; Muijzer, G.; Stan-Lotter, H.; van Loosdrecht, M. C. M.; Ehrenfreund, P.

    2010-11-01

    Halophilic archaea are of interest to astrobiology due to their survival capabilities in desiccated and high salt environments. The detection of remnants of salty pools on Mars stimulated investigations into the response of haloarchaea to martian conditions. Natronorubrum sp. strain HG-1 is an extremely halophilic archaeon with unusual metabolic pathways, growing on acetate and stimulated by tetrathionate. We exposed Natronorubrum strain HG-1 to ultraviolet (UV) radiation, similar to levels currently prevalent on Mars. In addition, the effects of low temperature (4, -20, and -80 °C), desiccation, and exposure to a Mars soil analogue from the Atacama desert on the viability of Natronorubrum strain HG-1 cultures were investigated. The results show that Natronorubrum strain HG-1 cannot survive for more than several hours when exposed to UV radiation equivalent to that at the martian equator. Even when protected from UV radiation, viability is impaired by a combination of desiccation and low temperature. Desiccating Natronorubrum strain HG-1 cells when mixed with a Mars soil analogue impaired growth of the culture to below the detection limit. Overall, we conclude that Natronorubrum strain HG-1 cannot survive the environment currently present on Mars. Since other halophilic microorganisms were reported to survive simulated martian conditions, our results imply that survival capabilities are not necessarily shared between phylogenetically related species.

  3. 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

  4. High altitude artisanal small-scale gold mines are hot spots for Mercury in soils and plants

    International Nuclear Information System (INIS)

    Terán-Mita, Tania A.; Faz, Angel; Salvador, Flor; Arocena, Joselito M.; Acosta, Jose A.

    2013-01-01

    Mercury releases from artisanal and small-scale gold mines (ASGM) condense and settle on plants, soils and water bodies. We collected soil and plant samples to add knowledge to the likely transfer of Hg from soils into plants and eventually predict Hg accumulation in livestock around ASGM in Bolivia. Mean contents of Hg in soils range from 0.5 to 48.6 mg Hg kg −1 soil (5× to 60× more compared to control sites) and exceeded the soil Hg threshold levels in some European countries. The Hg contents ranged from 0.6 to 18 and 0.2 to 28.3 mg Hg kg −1 leaf and root, respectively. The high Hg in Poaceae and Rosaceae may elevate Hg accumulation into the food chain because llama and alpaca solely thrive on these plants for food. Erosion of soils around ASGM in Bolivia contributes to the Hg contamination in lower reaches of the Amazon basin. - Highlights: ► Hg in soils ranged from 0.5 to 48.6 mg Hg kg −1 soil, and at least 5× to 60× more than control sites. ► Plants near gold mines exceed the 0.1 mg Hg kg −1 plant material European limit for feed quality. ► Camelids feeding on plants with high Hg may elevate Hg levels in foods (meats) for the miners. ► Soils with high Hg can be significant Hg sources to the contamination of the Amazon basin. - Mean contents of Hg in soils were at least 5× to 60× more compared to Hg in control sites, and the high Hg in Poaceae and Rosaceae may elevate Hg into the food chain.

  5. Gaseous mercury fluxes from forest soils in response to forest harvesting intensity: A field manipulation experiment

    Science.gov (United States)

    M. Mazur; C.P.J. Mitchell; C.S. Eckley; S.L. Eggert; R.K. Kolka; S.D. Sebestyen; E.B. Swain

    2014-01-01

    Forest harvesting leads to changes in soil moisture, temperature and incident solar radiation, all strong environmental drivers of soil-air mercury (Hg) fluxes. Whether different forest harvesting practices significantly alter Hg fluxes from forest soils is unknown.We conducted a field-scale experiment in a northern Minnesota deciduous forest wherein gaseous Hg...

  6. 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...

  7. Soil efflux and total emission rates of magmatic CO2 at the horseshoe lake tree kill, mammoth mountain, California, 1995-1999

    Science.gov (United States)

    Gerlach, T.M.; Doukas, M.P.; McGee, K.A.; Kessler, R.

    2001-01-01

    We report the results of eight soil CO2 efflux surveys by the closed circulation chamber method at the Horseshoe Lake tree kill (HLTK) - the largest tree kill on Mammoth Mountain. The surveys were undertaken from 1995 to 1999 to constrain total HLTK CO2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills. HLTK effluxes range from 1 to > 10,000 g m -2 day -1 (grams CO2 per square meter per day); they are not normally distributed. Station efflux rates can vary by 7-35% during the course of the 8- to 16-h surveys. Disturbance of the upper 2 cm of ground surface causes effluxes to almost double. Semivariograms of efflux spatial covariance fit exponential or spherical models; they lack nugget effects. Efflux contour maps and total CO2 emission rates based on exponential, spherical, and linear kriging models of survey data are nearly identical; similar results are also obtained with triangulation models, suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions. In addition, model estimates of total CO2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of CO2. Surveys since 1997 indicate that, contrary to earlier speculations, a termination of elevated CO2 emissions at the HLTK is unlikely anytime soon. The HLTK CO2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995-1999 surveys but maintained a N-S elongation, presumably reflecting fault control of CO2 transport from depth. Total CO2 emission rates also fluctuated greatly, ranging from 46 to 136 t day-1 (metric tons CO2 per day) and averaging 93 t day-1. The large inter-survey variations are caused primarily by external (meteorological) processes operating on time scales of hours to days. The externally caused variations can mask significant changes occurring at depth; a striking example is

  8. 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

  9. Understanding the paradox of selenium contamination in mercury mining areas: high soil content and low accumulation in rice.

    Science.gov (United States)

    Zhang, Hua; Feng, Xinbin; Jiang, Chengxin; Li, Qiuhua; Liu, Yi; Gu, Chunhao; Shang, Lihai; Li, Ping; Lin, Yan; Larssen, Thorjørn

    2014-05-01

    Rice is an important source of Se for billions of people throughout the world. The Wanshan area can be categorized as a seleniferous region due to its high soil Se content, but the Se content in the rice in Wanshan is much lower than that from typical seleniferous regions with an equivalent soil Se level. To investigate why the Se bioaccumulation in Wanshan is low, we measured the soil Se speciation using a sequential partial dissolution technique. The results demonstrated that the bioavailable species only accounted for a small proportion of the total Se in the soils from Wanshan, a much lower quantity than that found in the seleniferous regions. The potential mechanisms may be associated with the existence of Hg contamination, which is likely related to the formation of an inert Hg-Se insoluble precipitate in soils in Wanshan. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. 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.

  11. Influence of rice straw amendment on mercury methylation and nitrification in paddy soils

    International Nuclear Information System (INIS)

    Liu, Yu-Rong; Dong, Ji-Xin; Han, Li-Li; Zheng, Yuan-Ming; He, Ji-Zheng

    2016-01-01

    Currently, rice straw return in place of burning is becoming more intensive in China than observed previously. However, little is known on the effect of returned rice straw on mercury (Hg) methylation and microbial activity in contaminated paddy fields. Here, we conduct a microcosm experiment to evaluate the effect of rice straw amendment on the Hg methylation and potential nitrification in two paddy soils with distinct Hg levels. Our results show that amended rice straw enhanced Hg methylation for relatively high Hg content soil, but not for low Hg soil, spiking the same additional fresh Hg. methylmercury (MeHg) concentration was significantly correlated to the dissolved organic carbon (DOC) content and relative abundance of dominant microbes associated with Hg methylation. Similarly, amended rice straw was found to only enhance the potential nitrification rate in soil with relatively high Hg content. These findings provide evidence that amended rice straw differentially modulates Hg methylation and nitrification in Hg contaminated soils possibly resulting from different characteristics in the soil microbial community. This highlights that caution should be taken when returning rice straw to contaminated paddy fields, as this practice may increase the risk of more MeHg production. Main finding: Rice straw amendment enhanced both Hg methylation and nitrification potential in the relatively high, but not low, Hg soil. - Highlights: • Rice straw enhanced Hg methylation in relatively high Hg content paddy soils. • Microbial community directly correlated to the Hg methylation. • Mercury methylation in soils depend on Hg bioavailability and microbial activities. • Hg input affects microbial community associated with decomposition of rice straw.

  12. Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia.

    Science.gov (United States)

    Chouvelon, Tiphaine; Warnau, Michel; Churlaud, Carine; Bustamante, Paco

    2009-01-01

    There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature.

  13. Effect of Elodea nuttallii roots on bacterial communities and MMHg proportion in a Hg polluted sediment.

    Science.gov (United States)

    Regier, Nicole; Frey, Beat; Converse, Brandon; Roden, Eric; Grosse-Honebrink, Alexander; Bravo, Andrea Garcia; Cosio, Claudia

    2012-01-01

    The objective of this study was to assess the effect of a rooted macrophyte Elodea nuttallii on rhizosphere bacterial communities in Hg contaminated sediments. Specimens of E. nuttallii were exposed to sediments from the Hg contaminated Babeni reservoir (Olt River, Romania) in our microcosm. Plants were allowed to grow for two months until they occupied the entirety of the sediments. Total Hg and MMHg were analysed in sediments where an increased MMHg percentage of the total Hg in pore water of rhizosphere sediments was found. E. nuttallii roots also significantly changed the bacterial community structure in rhizosphere sediments compared to bulk sediments. Deltaproteobacteria dominated the rhizosphere bacterial community where members of Geobacteraceae within the Desulfuromonadales and Desulfobacteraceae were identified. Two bacterial operational taxonomic units (OTUs) which were phylogenetically related to sulfate-reducing bacteria (SRB) became abundant in the rhizosphere. We suggest that these phylotypes could be potentially methylating bacteria and might be responsible for the higher MMHg percentage of the total Hg in rhizosphere sediments. However, SRB were not significantly favoured in rhizosphere sediments as shown by qPCR. Our findings support the hypothesis that rooted macrophytes created a microenvironment favorable for Hg methylation. The presence of E. nuttallii in Hg contaminated sediments should therefore not be overlooked.

  14. Effect of Elodea nuttallii roots on bacterial communities and MMHg proportion in a Hg polluted sediment.

    Directory of Open Access Journals (Sweden)

    Nicole Regier

    Full Text Available The objective of this study was to assess the effect of a rooted macrophyte Elodea nuttallii on rhizosphere bacterial communities in Hg contaminated sediments. Specimens of E. nuttallii were exposed to sediments from the Hg contaminated Babeni reservoir (Olt River, Romania in our microcosm. Plants were allowed to grow for two months until they occupied the entirety of the sediments. Total Hg and MMHg were analysed in sediments where an increased MMHg percentage of the total Hg in pore water of rhizosphere sediments was found. E. nuttallii roots also significantly changed the bacterial community structure in rhizosphere sediments compared to bulk sediments. Deltaproteobacteria dominated the rhizosphere bacterial community where members of Geobacteraceae within the Desulfuromonadales and Desulfobacteraceae were identified. Two bacterial operational taxonomic units (OTUs which were phylogenetically related to sulfate-reducing bacteria (SRB became abundant in the rhizosphere. We suggest that these phylotypes could be potentially methylating bacteria and might be responsible for the higher MMHg percentage of the total Hg in rhizosphere sediments. However, SRB were not significantly favoured in rhizosphere sediments as shown by qPCR. Our findings support the hypothesis that rooted macrophytes created a microenvironment favorable for Hg methylation. The presence of E. nuttallii in Hg contaminated sediments should therefore not be overlooked.

  15. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    Science.gov (United States)

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

  16. Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats.

    Science.gov (United States)

    Zhang, Bin-Bin; Li, Wen-Kai; Hou, Wei-Yu; Luo, Ya; Shi, Jing-Zhen; Li, Cen; Wei, Li-Xin; Liu, Jie

    2017-09-15

    Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl 2 ) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl 2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl 2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl 2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl 2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl 2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. 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.)

  18. Soil Scientific Research Methods Used in Archaeology – Promising Soil Biochemistry: a Mini-review

    Directory of Open Access Journals (Sweden)

    Valerie Vranová

    2015-01-01

    Full Text Available This work seeks to review soil scientific methods that have been used and are still being used in archaeology. This review paper aims at emphasising the importance of soil science practice to archaeology thus adding a scientific analytical nature to the cultural nature of archaeology. Common methods (physical, chemical and biochemical used to analyse archaeological soils and artefacts is touched on and their strengths and shortcomings duly noted to become the base for future research. Furthermore, the authors made emphasis on distinctive excavating/sampling methods, biochemical analyses focused on distinctive features of plough-land and soil organic matter mineralization, Counter Immunoelectrophoresis (CEIP method by the presence of proteins testing, carbon analyses such as carbon-14 dating techniques, soil phosphorus studies and geochemical analyses of hematite Fe2O3 and cinnabaryte HgS contents. It is obvious that, the future of archaeology is in the soil because the soil harbours information of the past hence the synergy between soil and archaeological research has to be strengthened and archaeology made a prime agenda by soil scientists by expanding the analyses scope of total phosphorus extraction and giving attention to soil magnetism.

  19. 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

  20. 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

  1. Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

    Directory of Open Access Journals (Sweden)

    C. Milzow

    2011-06-01

    Full Text Available The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly gauged Okavango catchment in Southern Africa: (i surface soil moisture (SSM estimates derived from radar measurements onboard the Envisat satellite; (ii radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about one hundred meters; and (iii temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation of the precipitation input. The accuracy of the radar altimetry data is validated on gauged subbasins of the catchment and altimetry data of an ungauged subbasin is used for model calibration. The radar altimetry data are important to condition model parameters related to channel morphology such as Manning's roughness. GRACE data are used to validate the model and to condition model parameters related to various storage compartments in the hydrological model (e.g. soil, groundwater, bank storage etc.. As precipitation input the FEWS-Net RFE, TRMM 3B42 and ECMWF ERA-Interim datasets are considered and compared.

  2. 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

  3. Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

    DEFF Research Database (Denmark)

    Milzow, Christian; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

    2011-01-01

    The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly...... gauged Okavango catchment in Southern Africa: (i) surface soil moisture (SSM) estimates derived from radar measurements onboard the Envisat satellite; (ii) radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about...... one hundred meters; and (iii) temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE) caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation...

  4. 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

  5. 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.

  6. 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

  7. Impact of forested fallows on fertility and mercury content in soils of the Tapajós River region, Brazilian Amazon.

    Science.gov (United States)

    Patry, Cynthia; Davidson, Robert; Lucotte, Marc; Béliveau, Annie

    2013-08-01

    Recent research on slash-and-burn agriculture conducted in the Amazonian basin has suggested that soils must be left under forested fallows for at least 10 to 15 years to regain fertility levels comparable to non-disturbed forests in order to allow for short cycle crop cultivation. However, small scale farmers tend nowadays to re-burn secondary forests as soon as after 3 to 5 years, thus could contribute to further reduce soil fertility and could enhance the transfer of mercury (Hg) naturally present in soils of the region towards water courses. The present research project sets out to characterize the impact of forested fallows of differing age and land-use history on soils properties (fertility and Hg contents) in the region of the Tapajós River, an active pioneer front of the Brazilian Amazon. To do this, soil samples in forested fallows of variable age and in control primary forests were retrieved. In general, soil fertility of grouped forested fallows of different ages was similar to that of the primary forests. But when discriminating soils according to their texture, forested fallows on coarse grained soils still had much higher NH4/NO3 ratios, NH4 and Ca contents than primary forests, this even 15 years after burning. The impact of repeated burnings was also assessed. Fallows on coarse grained soils showed an impoverishment for all variables related to fertility when the number of burnings was 5 or more. For fallows on fine grained soils that underwent 5 or more burnings, NO3 contents were low although a cation enrichment was observed. Total soil Hg content was also sensitive to repeated burnings, showing similar losses for forested fallows established on both types of soil. However, Hg linked to coarse particles appeared to migrate back towards fine particles at the surface of coarse grained soils in fallows older than 7 years. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Assessment and source identification of trace metals in the soils of greenhouse vegetable production in eastern China.

    Science.gov (United States)

    Yang, Lanqin; Huang, Biao; Hu, Wenyou; Chen, Yong; Mao, Mingcui

    2013-11-01

    Worldwide concern about the occurrence of trace metals in greenhouse vegetable production soils (GVPS) is growing. In this study, a total of 385 surface GVPS samples were collected in Shouguang and four vegetable production bases in Nanjing, Eastern China, for the determination of As and Hg using atomic fluorescence spectrometry and Pb, Cu, Cd, and Zn using inductively coupled plasma-mass spectrometry. Geo-accumulation indices and factor analysis were used to investigate the accumulation and sources of the trace metals in soils in Eastern China. The results revealed that greenhouse production practices increased accumulation of the trace metals, particularly Cd, Zn, and Cu in soils and their accumulation became significant with increasing years of cultivation. Accumulation of Cd and Zn was also found in soils from organic greenhouses. The GVPS was generally less polluted or moderately polluted by As, Cu, Zn, and Pb but heavily polluted by Cd and Hg in some locations. Overall, accumulation of Cd, Zn, and Cu in GVPS was primarily associated with anthropogenic activities, particularly, application of manure. The high level of Hg found in some sites was related to historical heavy application of Hg containing pesticides. However, further identification of Hg sources is needed. To reduce accumulation of the trace metals in GVPS, organic fertilizer application should be suggested through development and implementation of reasonable and sustainable strategies. © 2013 Elsevier Inc. All rights reserved.

  9. Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization.

    Science.gov (United States)

    Kim, Han Sik; Jung, Myung Chae

    2012-01-01

    This survey aimed to compare mercury concentrations in soils related to geology and mineralization types of mines. A total of 16,386 surface soils (0~15 cm in depth) were taken from agricultural lands near 343 abandoned mines (within 2 km from each mine) and analyzed for Hg by AAS with a hydride-generation device. To meaningfully compare mercury levels in soils with geology and mineralization types, three subclassification criteria were adapted: (1) five mineralization types, (2) four valuable ore mineral types, and (3) four parent rock types. The average concentration of Hg in all soils was 0.204 mg kg(-1) with a range of 0.002-24.07 mg kg(-1). Based on the mineralization types, average Hg concentrations (mg kg(-1)) in the soils decreased in the order of pegmatite (0.250) > hydrothermal vein (0.208) > hydrothermal replacement (0.166) > skarn (0.121) > sedimentary deposits (0.045). In terms of the valuable ore mineral types, the concentrations decreased in the order of Au-Ag-base metal mines ≈ base metal mines > Au-Ag mines > Sn-W-Mo-Fe-Mn mines. For parent rock types, similar concentrations were found in the soils derived from sedimentary rocks and metamorphic rocks followed by heterogeneous rocks with igneous and metamorphic processes. Furthermore, farmland soils contained relatively higher Hg levels than paddy soils. Therefore, it can be concluded that soils in Au, Ag, and base metal mines derived from a hydrothermal vein type of metamorphic rocks and pegmatite deposits contained relatively higher concentrations of mercury in the surface environment.

  10. A Linkage Between Parent Materials of Soil and Potential Risk of Heavy Metals in Yunnan province, China

    Science.gov (United States)

    Cheng, X.

    2015-12-01

    A large area exceeding soil quality standards for heavy metals in South western China has been identified previously reported on a nationwide survey of soil pollution, yet the ecological risk of heavy metal in soil is unknown or uncertainty.To assess thoroughly the ecological risk in this region, seven soil profiles with a depth of 2m on the different parent materials of soil were conducted in Yunnan province, China, and the level of total concentrations and the fraction of water soluble, ion exchangeable, carbonates, humic acid, iron and manganese oxides and organic matter of As, Cd, Hg and Pb was investigated in soil profiles. The results indicate that parent materials of soil critically influenced the ecological risk of heavy metal.The fraction of water soluble and ion exchangeable of Cd and Hg in alluvial material and in terrigenous clastic rocks showed 2-6 times higher than those in carbonate rock; As and Pb has almost same fraction of water soluble and ion exchangeable in three parent materials of soil.The findings suggest that parent materials of soil play a critical role in ecological risk of heavy metal.Thus, more studies are needed to better understand a linkage between the parent materials of soil, different soil-forming processes and the potential risk of heavy metals under various geographic conditions, which is the key for the evaluating soil quality and food safety. Those soils with high concentration of Cd and Hg originated alluvial material and terrigenous clastic rocks need to be continuously monitored before determining a cost-effective remediation technology. Keywords: Heavy metals; Ecological risk;Parent materials of soil;China

  11. Long-term mercury dynamics in UK soils

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E., E-mail: et@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Wadsworth, R.A. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Norris, D.A.; Hall, J.R. [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Ilyin, I. [Meteorological Synthesizing Centre - East, Krasina pereulok, 16/1, 123056 Moscow (Russian Federation)

    2011-12-15

    A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 {mu}g Hg m{sup -2} a{sup -1} to rural soils, 19 {mu}g Hg m{sup -2} a{sup -1} to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg{sup 0} per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: > Spatial data for mercury in UK soils can be related to past atmospheric deposition. > The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. > UK soils currently contribute more Hg{sup 0} to the atmosphere than human activities. > Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg{sup 0} to the global circulation.

  12. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    International Nuclear Information System (INIS)

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger

  13. Carbono orgânico e nitrogênio total do solo e suas relações com os espaçamentos de plantio de cafeeiro Soil organic carbon and total nitrogen as related with coffee spacing

    Directory of Open Access Journals (Sweden)

    Otacílio José Passos Rangel

    2008-10-01

    Full Text Available A densidade de plantio e o arranjo das plantas exercem influência sobre a produção de resíduos vegetais nos agroecossistemas cafeeiros. Esse aporte diferenciado de resíduos regula os teores de C e N do solo. Este trabalho objetivou avaliar os teores de C orgânico e de N total em um Latossolo Vermelho distrófico cultivado com cafeeiro com diversos espaçamentos de plantio. O experimento foi conduzido no período de 1992 a 2004 na Fazenda Experimental da EPAMIG, em Machado (MG. Os tratamentos avaliados consistiram da combinação de quatro espaçamentos entre linhas (2,0; 2,5; 3,0; e 3,5 m, três espaçamentos entre plantas (0,5; 0,75; e 1,0 m e dois sistemas de manejo dos resíduos culturais (entrelinha - EL e projeção da copa - PC, totalizando 24 tratamentos, dispostos no campo em blocos ao acaso, em esquema fatorial 4 x 3 x 2, com três repetições. Foram avaliados os teores de C orgânico (CO e de N total do solo (NT, além da relação CO/NT. Nas amostras de solo da EL, os teores de CO e NT foram maiores do que os da PC. O espaçamento de plantio influenciou os teores de CO, com os maiores valores, em geral, no espaçamento de 3,5 m entre as linhas de plantio, quando a distância entre plantas foi de 0,5 e 0,75 m, na profundidade de 0-0,05 m. O maior acúmulo de resíduos vegetais, o menor revolvimento do solo e, conseqüentemente, os maiores teores de matéria orgânica favorecem a ocorrência de maiores teores de CO e NT na EL. A retirada da mata e o cultivo do solo com cafeeiro por 11 anos resultou em decréscimo nos teores de CO de 26 % a 38 % na EL e na PC, respectivamente, e diminuição média de 25 % nos teores de NT.The density and arrangement of trees influences the production of plant residues in coffee agroecosystems. This differentiated input of biomass regulates the contents of soil-C and -N. This study aimed to evaluate the contents of organic C and total N in a Typic Hapludox, in different spacings of (Coffea arabica

  14. 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

  15. 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.)

  16. Quasiparticle excitations in superdeformed {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Carpenter, M.P.; Janssens, R.V.F. [and others

    1995-08-01

    The nucleus {sup 192}Hg plays a pivotal role for superdeformation in the mass 190 region, since calculations of single-particle levels show large shell-gaps for the superdeformed (SD) shape at N = 112 and Z = 80. As a result, {sup 192}Hg is referred to as the doubly magic SD nucleus for the A = 190 region. In previous studies, only one superdeformed band was observed in this nucleus, and this fact was cited as indirect evidence that large shell gaps do indeed exist at the proposed particle numbers.

  17. Coulomb excitation of 206Hg at relativistic energies

    Science.gov (United States)

    Alexander, Tom

    The region of the nuclear chart surrounding the doubly-magic nucleus 208Pb provides a key area to constrain and develop contemporary nuclear structure models. One aspect of particular interest is the transition strength of the first excited 2+ state in even-even nuclei; this work describes the measurement of this value for the case of 206Hg, where the Z=80 line meets the N=126 shell closure. The nuclei of interest were synthesized using relativistic-energy projectile fragmentation at the GSI facility in Germany. They were produced in the fragmentation of a primary 208Pb beam at an energy of 1 GeV per nucleon, and separated and identifed using the Fragment Separator. The secondary beams with an energy of 140 MeV per nucleon were Coulomb excited on a secondary target of 400 mg/cm. 2 gold. Gamma-rays were detected with the Advanced GAmma Tracking Array (AGATA). The precise scattering angle for Doppler-correction was determined with position information from the Lund-York-Cologne-CAlorimeter(LYCCA). Using the sophisticated tracking algorithm native to AGATA in conjunction with pulse-shape analysis, a precise Doppler-correction is performed on the gamma spectra, and using a complex n-dimensional analysis, the B(E2) value for 206Hg is extracted relative to the known value also measured in 206Pb. A total of 409 million 206Hg particles were measured, and a cross-section of 50 mb was determined for the 2+ state at 1068 keV. The measurement of the B(E2) transition strength was found to be 1.109 W.u. This result is compared to a number of theoretical calculations, including two Gogny forces, and a modified shell model parametrization and is found to be smaller than all calculated estimations, implying that the first excited 2. + state in . {206}Hg is uncollective in nature.

  18. Speciation of aquatic Hg2+ in humic substances by time differential perturbed angular correlation

    International Nuclear Information System (INIS)

    Franke, K.; Kupsch, H.; Troger, W.; Butz, T.

    1997-01-01

    Humic substances are ubiquitous in waters and soils and act as complexing agents for different heavy metals, e.g. Cd, Hg. Toxicity, reactivity, fixation, and migration are therefore strongly influenced by the interactions between heavy metals and humic substances. Humic substances derive from postmortal materials such as rotten plants, have dark colours and usually a molecular weight between 500 and 10.000 Dalton. Complex formation studies with different heavy metal ions indicate at least two different kinds of metal sites. Usually, these studies are restricted to heavy metal concentrations 2 to 3 orders of magnitude higher that the natural heavy metal abundance (i.e. 10 -10 molar). This serious limitation can be overcome by the use of suitable radioisotope techniques capable of metal speciation at extreme sensitivity levels such as TDPAC (Time Differential Perturbed Angular Correlation of γ-Rays). Thus, we studied the interaction of heavy metals with humic substances by monitoring the nuclear quadrupole interaction (NQI)of the short-lived radioisotopes 111m Cd (τ l/2 = 49 min) and 199m Hg (τ 1/2 = 43 min) supplied by ISOLDE via γ-γ -TDPAC and compared the 111m Cd/ 199m Hg-NQIs in humic substances with the known NQI of model compounds (i.e. metal proteins, organometallic compounds). At lowest Hg(II) concentrations (10 -10 molar) only linear Hg(ll) coordinations with nitrogen and/or sulfur were observed, with increasing Hg(II) concentration additional distorted trigonal (at 2.5.10 -10 molar) and tetrahedral coordinations (at 2.5.10 -8 molar) with various ligands show up and start to become dominant at Hg(II) concentrations of 10 -7 molar and higher. Contrary to Hg(II), we observed unspecific binding for Cd(lI) in the 111m Cd-TDPAC experiments only, even in the 10 -10 molar concentration range

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. Heavy metal pollution in soil associated with a large-scale cyanidation gold mining region in southeast of Jilin, China.

    Science.gov (United States)

    Chen, Mo; Lu, Wenxi; Hou, Zeyu; Zhang, Yu; Jiang, Xue; Wu, Jichun

    2017-01-01

    Different gold mining and smelting processes can lead to distinctive heavy metal contamination patterns and results. This work examined heavy metal pollution from a large-scale cyanidation gold mining operation, which is distinguished from artisanal and small-scale amalgamation gold mining, in Jilin Province, China. A total of 20 samples including one background sample were collected from the surface of the mining area and the tailings pond in June 2013. These samples were analyzed for heavy metal concentrations and degree of pollution as well as sources of Cr, Cu, Zn, Pb, Ni, Cd, As, and Hg. The mean concentrations of Pb, Hg, and Cu (819.67, 0.12, and 46.92 mg kg -1 , respectively) in soil samples from the gold mine area exceeded local background values. The mean Hg content was less than the first-class standard of the Environmental Quality for Soils, which suggested that the cyanidation method is helpful for reducing Hg pollution. The geochemical accumulation index and enrichment factor results indicated clear signs that enrichment was present for Pb, Cu, and Hg, with the presence of serious Pb pollution and moderate presence to none of Hg and Cu pollution. Multivariate statistical analysis showed that there were three metal sources: (1) Pb, Cd, Cu, and As came from anthropogenic sources; (2) Cr and Zn were naturally occurring; whereas (3) Hg and Ni had a mix of anthropogenic and natural sources. Moreover, the tailings dam plays an important role in intercepting the tailings. Furthermore, the potential ecological risk assessment results showed that the study area poses a potentially strong risk to the ecological health. Furthermore, Pb and Hg (due to high concentration and high toxicity, respectively) are major pollutants on the risk index, and both Pb and Hg pollution should be of great concern at the Haigou gold mines in Jilin, China.

  7. 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

  8. 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

  9. Binding, distribution, and plant uptake of mercury in a soil from Oak Ridge, Tennessee, USA.

    Science.gov (United States)

    Han, Fengxiang X; Su, Yi; Monts, David L; Waggoner, Charles A; Plodinec, M John

    2006-09-15

    A large amount of mercury has been discharged on the U.S. Department of Energy's Oak Ridge Site (Tennessee) as a part of the U.S. nuclear weapon program during the 1950s through the early 1960s. Increases in mercury concentration in fish and in lower East Fork Poplar Creek of Oak Ridge have been recently reported. This is an experimental study mimicking the initial stage of transformation and redistribution of mercury in soils, which are comparable to those of the Oak Ridge site. The objectives of this study were to investigate potential transformation, distribution, and plant uptake of mercury compounds in soils. Results show that the H(2)O(2)-oxidizable mercury fraction (organically bound mercury) was the major solid-phase fraction in soils freshly contaminated with soluble mercury compounds, while cinnabar fraction was the major solid phase fraction in soils contaminated with HgS. Langmuir relationships were found between mercury concentrations in plant shoots and in soil solid-phase components. Mercury in HgS-contaminated soils was to some extent phytoavailable to plants. Mercury transformation occurred from more labile fractions into more stable fractions, resulting in strong binding of mercury and decreasing its phytoavailability in soils. In addition, high mercury losses from soils contaminated with soluble mercury compounds were observed during a growing season through volatilization, accounting for 20-62% of the total initial mercury in soils.

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. Single crystal growth, electronic structure and optical properties of Cs2HgBr4

    Science.gov (United States)

    Lavrentyev, A. A.; Gabrelian, B. V.; Vu, V. T.; Shkumat, P. N.; Parasyuk, O. V.; Fedorchuk, A. O.; Khyzhun, O. Y.

    2015-10-01

    We report on successful synthesis of high-quality single crystal of cesium mercury tetrabromide, Cs2HgBr4, by using the vertical Bridgman-Stockbarger method as well as on studies of its electronic structure. For the Cs2HgBr4 crystal, we have recorded X-ray photoelectron spectra for both pristine and Ar+ ion-bombarded surfaces. Our data indicate that the Cs2HgBr4 single crystal surface is rather sensitive with respect to Ar+ ion-bombardment. In particular, such a treatment of the Cs2HgBr4 single crystal surface alters its elemental stoichiometry. To explore peculiarities of the energy distribution of total and partial densities of states within the valence band and the conduction band of Cs2HgBr4, we have made band-structure calculations based on density functional theory (DFT) employing the augmented plane wave+local orbitals (APW+lo) method as incorporated in the WIEN2k package. The APW+lo calculations allow for concluding that the Br 4p states make the major contributions in the upper portion of the valence band, while its lower portion is dominated by contributors of the Hg 5d and Cs 5p states. Further, the main contributors to the bottom of the conduction band of Cs2HgBr4 are the unoccupied Br p and Hg s states. In addition, main optical characteristics of Cs2HgBr4 such as dispersion of the absorption coefficient, real and imaginary parts of dielectric function, electron energy-loss spectrum, refractive index, extinction coefficient and optical reflectivity have been explored from the first-principles band-structure calculations.

  15. 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.

  16. Productivity, total and utilized nitrogen and water use efficiency of soybean grown in reclaimed sandy soil as affected by water regime

    International Nuclear Information System (INIS)

    Abdallah, A.A.G.; Thabet, E.M.A.

    2002-01-01

    Field experiment was performed at the experimental farm, Inshas, atomic energy authority, Egypt, in tafla and sand mixture soil (1:7). The experiment was laid out using sprinkler irrigation system with a line source which allows a gradual variation of irrigation from high to low irrigation, whereas the calculated amount of irrigation water levels were 1565, 1050 and 766.5 (m 3 / feddan). Two soybean varieties (crawford and giza 35) were planted. The obtained results indicated that: a) irrigation with high (1562 m 3 /fed.) and medium (1050 m 3 /fed.) water levels increased total seed wield of the two soybean varieties. b) the highest value of water use efficiency was observed when both soybean varieties irrigated with water level of 1050 m 3 /fed. c) seed protein content in crawford variety was higher in giza 35 variety at the irrigation level of 1562 m 3 /fed. d) seeds of both two soybean varieties showed increase of its atom excess percentage at high and medium water levels, and reflecting increase of nitrogen use efficiency. e) significant increment in seed yield kg/plot. Has been indicated by irrigation with water level of 1050 m 3 /fed. As compared to higher and lower water levels

  17. Hair mercury (Hg) levels, fish consumption and semen parameters among men attending a fertility center.

    Science.gov (United States)

    Mínguez-Alarcón, Lidia; Afeiche, Myriam C; Williams, Paige L; Arvizu, Mariel; Tanrikut, Cigdem; Amarasiriwardena, Chitra J; Ford, Jennifer B; Hauser, Russ; Chavarro, Jorge E

    2018-03-01

    General population exposure to methylmercury (MeHg), the most common organic mercury compound found in the environment, occurs primarily through the consumption of contaminated fish and shellfish. Due to limited studies and lack of consideration of effect modification by fish consumption, it remains uncertain if exposure to mercury affects semen parameters. Thus, we investigated whether hair Hg levels, a biomarker of mercury exposure, were associated with semen parameters among men attending an academic fertility center, and whether this relationship was modified by intake of fish. This analysis included 129 men contributing 243 semen samples who were enrolled in the Environment and Reproductive Health (EARTH) Study between 2005 and 2013, and had data of hair Hg, intake of fish and semen parameters available. Hair Hg levels were assessed using a direct mercury analyzer. Intake of fish was collected using a validated food frequency questionnaire. Semen parameters were analyzed following WHO 2010 evaluation criteria. Generalized linear mixed models with random intercepts accounting for within-man correlations across semen samples were used to evaluate the association of hair Hg levels and semen parameters adjusting for age, BMI, smoking status, abstinence time and alcohol intake. Effect modification by total fish intake (≤1.68 vs. >1.68 servings/week) was tested. The median hair Hg levels of the men was 0.72ppm and ranged from 0.03 to 8.01ppm; almost 30% of the men had hair Hg levels >1ppm. Hair Hg levels were positively related with sperm concentration, total sperm count, and progressive motility, after adjusting for potential confounders and became attenuated after further adjustment for fish intake. Specifically, men in the highest quartile of hair mercury levels had 50%, 46% and 31% higher sperm concentration, total sperm count and progressive motility, respectively, compared to men in the lowest quartile. These associations were stronger among men whose fish

  18. Differential determination of 203Hg and 14C or 35S in double labelled biological samples

    International Nuclear Information System (INIS)

    Bem, E.M.; Bem, H.; Reimschussel, W.

    1979-01-01

    The differential determination of 203 Hg and 14 C or 35 S in double labelled biological samples is presented. The biological samples were mineralized with 70% HClO 4 and 30% H 2 O 2 in glass vials, MILLI-6. The γ-activity of 203 Hg was measured on a well scintillation counter. The total activity, due to 203 Hg and 14 C or 35 S, was measured by the liquid scintillation technique after addition of Aquasol into the same vials. The method of external standard channel ratio was used for standardization. Very good recoveries were obtained: 100+-0.7% for 203 Hg and 94.6-101.0% for 14 C and 35 S. This method could be used for other β, γ and β-active nuclides with similar β-spectra. (author)

  19. Alterations in biochemical markers due to mercury (Hg) exposure and its influence on infant's neurodevelopment.

    Science.gov (United States)

    Al-Saleh, Iman; Elkhatib, Rola; Al-Rouqi, Reem; Abduljabbar, Mai; Eltabache, Chafica; Al-Rajudi, Tahreer; Nester, Michael

    2016-11-01

    This study examined the role of oxidative stress due to mercury (Hg) exposure on infant's neurodevelopmental performance. A total of 944 healthy Saudi mothers and their respective infants (aged 3-12 months) were recruited from 57 Primary Health Care Centers in Riyadh City. Total mercury (Hg) was measured in mothers and infants urine and hair samples, as well as mother's blood and breast milk. Methylmercury (MeHg) was determined in the mothers and infants' hair and mother's blood. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), and porphyrins were used to assess oxidative stress. The infant's neurodevelopment was evaluated using Denver Developmental Screening Test II (DDST-II) and Parents' Evaluation of Developmental Status. The median total Hg levels in mother's urine, infant's urine, mother's hair, infant's hair, and mother's blood and breast milk were 0.995μg/l, 0.716μg/l, 0.118μg/g dw, 0.101μg/g dw, 0.635μg/l, and 0.884μg/l respectively. The median MeHg levels in mother's hair, infant's hair, and mother's blood were 0.132μg/g dw, 0.091μg/g dw, and 2.341μg/l respectively. A significant interrelationship between mothers and infants Hg measures in various matrices was noted. This suggests that mother's exposure to different forms of Hg (total and/or MeHg) from various sources contributed significantly to the metal body burden of their respective infants. Even though Hg exposure was low, it induced high oxidative stress in mothers and infants. The influence of multiplicative interaction terms between Hg measures and oxidative stress biomarkers was tested using multiple regression analysis. Significant interactions between the urinary Hg levels in mothers and infants and oxidative stress biomarkers (8-OHdG and MDA) were noted. The MeHg levels in mother-infant hair revealed similar interaction patterns. The p-values for both were below 0.001. These observations suggest that the exposure of our infants to Hg via mothers either during

  20. 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.

  1. Effects of the November 2012 Flood Event on the Mobilization of Hg from the Mount Amiata Mining District to the Sediments of the Paglia River Basin

    Directory of Open Access Journals (Sweden)

    Giulia Pattelli

    2014-04-01

    Full Text Available The Mount Amiata mining district (southern Tuscany, Italy was, for decades, one of the world’s largest mercury (Hg producing regions, where mining activity lasted until the 1980s. The Paglia River drains the eastern part of the district and is also the main western tributary of the Tiber River. Recent studies show that, still today, high total Hg contents severely affect the downstream ecosystems of these rivers. In November 2012, a major flood event occurred in the Paglia River basin, which drastically changed the river morphology and, possibly, the Hg concentrations. In the present work, stream sediment was sampled before and after the flood to evaluate possible changes in sediment total Hg concentrations as a consequence of this event. The comparison between pre- and post-flood Hg concentrations shows that Hg content increased up to an order of magnitude after the flood, suggesting that this event triggered Hg mobilization in the basin rather than its dilution.

  2. Combining Near-Infrared Spectroscopy and Chemometrics for Rapid Recognition of an Hg-Contaminated Plant

    Directory of Open Access Journals (Sweden)

    Bang-Cheng Tang

    2016-01-01

    Full Text Available The feasibility of rapid recognition of an Hg-contaminated plant as a soil pollution indicator was investigated using near-infrared spectroscopy (NIRS and chemometrics. The stem and leave of a native plant, Miscanthus floridulus (Labill. Warb. (MFLW, were collected from Hg-contaminated areas (n1=125 as well as from regular areas (n2=116. The samples were dried and crushed and the powders were sieved through an 80-mesh sieve. Reference analysis of Hg levels was performed using inductively coupled plasma-atomic emission spectrometry (ICP-AES. The actual Hg contents of contaminated and normal samples were 16.2–30.5 and 0.0–0.1 mg/Kg, respectively. The NIRS measurements of impacted sample powders were collected in the mode of reflectance. The DUPLEX algorithm was utilized to split the NIRS data into representative training and test sets. Different spectral preprocessing methods were performed to remove the unwanted and noncomposition-correlated spectral variations. Classification models were developed using partial least squares discrimination analysis (PLSDA based on the raw, smoothed, second-order derivative (D2, and standard normal variate (SNV data, respectively. The prediction accuracy obtained by PLSDA with each data preprocessing option was 100%, indicating pattern recognition of Hg-contaminated MFLW samples using NIRS data was in perfect consistence with the ICP-AES results. NIRS combined with chemometrics will provide a tool to screen the Hg-contaminated MFLW, which can be potentially used as an indicator of soil pollution.

  3. 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.

  4. 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

  5. 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)

  6. 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.

  7. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    International Nuclear Information System (INIS)

    Baldi, Franco; Gallo, Michele; Marchetto, Davide; Faleri, Claudia; Maida, Isabel; Fani, Renato

    2013-01-01

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l −1 HgCl 2 and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified with

  8. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Franco [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Gallo, Michele; Marchetto, Davide [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Faleri, Claudia [Department of Environmental Science ‘G. Sarfatti’, University of Siena, 53100 Siena (Italy); Maida, Isabel; Fani, Renato [Dipartimento di Biologia Evoluzionistica, Via Romana, 17, University of Florence, 50125 Florence (Italy)

    2013-08-15

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified

  9. 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

  10. Human biomonitoring for Cd, Hg and Pb in blood of inhabitants of the Sacco Valley (Italy

    Directory of Open Access Journals (Sweden)

    Sonia D'Ilio

    2013-03-01

    Full Text Available INTRODUCTION. The Sacco Valley (Lazio, Italy is characterized by high density population and several industrial chemical productions that during the time had led to a substantial amount of by-products. The result was a severe environmental pollution of the area and in particular of the river Sacco. In 1991, the analysis of water and soils samples of three industrial landfills revealed the presence of organochlorine compounds and heavy metals. A research project named "Health of residents living in Sacco Valley area", coordinated by the regional Department of Epidemiology, was undertaken and financed to evaluate the state of health of the population living near those polluted areas. MATERIALS AND METHODS. Cd, Hg and Pb were quantified in 246 blood samples of potentially exposed residents of the Sacco Valley by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS. RESULTS. Individuals who agreed to be sampled did not exhibit high levels of the elements. The distance from the river does not seem to be directly connected with the elements levels in blood. The contribution of these contaminants to the total intake due to ingestion of food was difficult to evaluate. The unclear trend of data would require a characterization of the polluted site with environmental sampling of different matrices.

  11. Total mercury and methylmercury accumulation in wild plants grown at wastelands composed of mine tailings: Insights into potential candidates for phytoremediation.

    Science.gov (United States)

    Qian, Xiaoli; Wu, Yonggui; Zhou, Hongyun; Xu, Xiaohang; Xu, Zhidong; Shang, Lihai; Qiu, Guangle

    2018-08-01

    Total mercury (THg) and methylmercury (MMHg) were investigated in 259 wild plants belonging to 49 species in 29 families that grew in heavily Hg-contaminated wastelands composed of cinnabar ore mine tailings (calcines) in the Wanshan region, southwestern China, the world's third largest Hg mining district. The bioconcentration factors (BCFs) of THg and MMHg from soil to roots ([THg] root /[THg] soil , [MMHg] root /[MMHg] soil ) were evaluated. The results showed that THg and MMHg in both plants and soils varied widely, with ranges of 0.076-140 μg/g THg and 0.19-87 ng/g MMHg in roots, 0.19-106 μg/g THg and 0.06-31 ng/g MMHg in shoots, and 0.74-1440 μg/g THg and 0.41-820 ng/g MMHg in soil. Among all investigated species, Arthraxon hispidus, Eremochloa ciliaris, Clerodendrum bunge, and Ixeris sonchifolia had significantly elevated concentrations of THg in shoots and/or roots that reached 100 μg/g, whereas Chenopodium glaucum, Corydalisedulis maxim, and Rumex acetosa contained low values below 0.5 μg/g. In addition to the high THg concentrations, the fern E. ciliaris also showed high BCF values for both THg and MMHg exceeding 1.0, suggesting its capability to extract Hg from soils. Considering its dominance and the tolerance identified in the present study, E. ciliaris is suggested to be a practical candidate for phytoextraction, whereas A. hispidus is identified as a potential candidate for phytostabilization of Hg mining-contaminated soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Heavy metals in soils of Hechuan County in the upper Yangtze (SW China): Comparative pollution assessment using multiple indices with high-spatial-resolution sampling.

    Science.gov (United States)

    Ni, Maofei; Mao, Rong; Jia, Zhongmin; Dong, Ruozhu; Li, Siyue

    2018-02-01

    In order to assess heavy metals (HMs) in soils of the upper Yangtze Basin, a very high-spatial-resolution sampling (582 soil samples) was conducted from Hechuan County, an important agricultural practice area in the Southwest China. Multiple indices including geoaccumulation index (I geo ), enrichment factor (EF), sediment pollution index (SPI) and risk index (RI), as well as multivariate statistics were employed for pollution assessment and source identification of HMs in soils. Our results demonstrated that the averages of eight HMs decreased in the following order: Zn (82.8 ± 15.9) > Cr (71.6 ± 12.2) > Ni (32.1 ± 9.89) > Pb (27.6 ± 13.8) > Cu (25.9 ± 11.8) > As (5.48 ± 3.42) > Cd (0.30 ± 0.077) > Hg (0.082 ± 0.092). Averages of HMs except Cd were lower than threshold value of Environmental Quality Standard for Soils, while 43% of total samples had Cd concentration exceeding the national standard, 1% of samples for Hg and 5% samples for Ni, moreover, Cd and Hg averages were much higher than their background levels. I geo and EF indicated that their levels decreased as follows: Cd > Hg > Zn > Pb > Ni > Cu > Cr > As, with moderate enrichments of Cd and Hg. RI indicated that 61.7% of all samples showed moderate risk, while 6.5% of samples with greater than considerable risk due to human activities should be paid more attention. Multivariate analysis showed lithogenic source of Cu, Cr, Ni and Zn, while Cd and Hg were largely contributed by anthropogenic activities such as agricultural practices. Our study would be helpful for improving soil environmental quality in SW, China, as well as supplying modern approaches for other areas with soil HM pollution. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. 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.

  14. 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...

  15. An integrated approach to assess heavy metal source apportionment in peri-urban agricultural soils

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ying; Li, Tingqiang; Wu, Chengxian [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); He, Zhenli [University of Florida, Institute of Food and Agricultural Sciences, Indian River Research and Education Center, Fort Pierce, FL 34945 (United States); Japenga, Jan; Deng, Meihua [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Yang, Xiaoe, E-mail: xeyang@zju.edu.cn [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China)

    2015-12-15

    Highlights: • Heavy metal source apportionment was conducted in peri-urban agricultural areas. • Precise and quantified results were obtained by using isotope ratio analysis. • The integration of IRA, GIS, PCA, and CA was proved to be more reliable. • Hg pollution was from the use of organic fertilizers in this area. - Abstract: Three techniques (Isotope Ratio Analysis, GIS mapping, and Multivariate Statistical Analysis) were integrated to assess heavy metal pollution and source apportionment in peri-urban agricultural soils. The soils in the study area were moderately polluted with cadmium (Cd) and mercury (Hg), lightly polluted with lead (Pb), and chromium (Cr). GIS Mapping suggested Cd pollution originates from point sources, whereas Hg, Pb, Cr could be traced back to both point and non-point sources. Principal component analysis (PCA) indicated aluminum (Al), manganese (Mn), nickel (Ni) were mainly inherited from natural sources, while Hg, Pb, and Cd were associated with two different kinds of anthropogenic sources. Cluster analysis (CA) further identified fertilizers, waste water, industrial solid wastes, road dust, and atmospheric deposition as potential sources. Based on isotope ratio analysis (IRA) organic fertilizers and road dusts accounted for 74–100% and 0–24% of the total Hg input, while road dusts and solid wastes contributed for 0–80% and 19–100% of the Pb input. This study provides a reliable approach for heavy metal source apportionment in this particular peri-urban area, with a clear potential for future application in other regions.

  16. An integrated approach to assess heavy metal source apportionment in peri-urban agricultural soils

    International Nuclear Information System (INIS)

    Huang, Ying; Li, Tingqiang; Wu, Chengxian; He, Zhenli; Japenga, Jan; Deng, Meihua; Yang, Xiaoe

    2015-01-01

    Highlights: • Heavy metal source apportionment was conducted in peri-urban agricultural areas. • Precise and quantified results were obtained by using isotope ratio analysis. • The integration of IRA, GIS, PCA, and CA was proved to be more reliable. • Hg pollution was from the use of organic fertilizers in this area. - Abstract: Three techniques (Isotope Ratio Analysis, GIS mapping, and Multivariate Statistical Analysis) were integrated to assess heavy metal pollution and source apportionment in peri-urban agricultural soils. The soils in the study area were moderately polluted with cadmium (Cd) and mercury (Hg), lightly polluted with lead (Pb), and chromium (Cr). GIS Mapping suggested Cd pollution originates from point sources, whereas Hg, Pb, Cr could be traced back to both point and non-point sources. Principal component analysis (PCA) indicated aluminum (Al), manganese (Mn), nickel (Ni) were mainly inherited from natural sources, while Hg, Pb, and Cd were associated with two different kinds of anthropogenic sources. Cluster analysis (CA) further identified fertilizers, waste water, industrial solid wastes, road dust, and atmospheric deposition as potential sources. Based on isotope ratio analysis (IRA) organic fertilizers and road dusts accounted for 74–100% and 0–24% of the total Hg input, while road dusts and solid wastes contributed for 0–80% and 19–100% of the Pb input. This study provides a reliable approach for heavy metal source apportionment in this particular peri-urban area, with a clear potential for future application in other regions.

  17. Impact of Soil Heavy Metal Pollution on Food Safety in China.

    Science.gov (United States)

    Zhang, Xiuying; Zhong, Taiyang; Liu, Lei; Ouyang, Xiaoying

    2015-01-01

    Food safety is a major concern for the Chinese public. This study collected 465 published papers on heavy metal pollution rates (the ratio of the samples exceeding the Grade II limits for Chinese soils, the Soil Environmental Quality Standard-1995) in farmland soil throughout China. The results showed that Cd had the highest pollution rate of 7.75%, followed by Hg, Cu, Ni and Zn, Pb and Cr had the lowest pollution rates at lower than 1%. The total pollution rate in Chinese farmland soil was 10.18%, mainly from Cd, Hg, Cu, and Ni. The human activities of mining and smelting, industry, irrigation by sewage, urban development, and fertilizer application released certain amounts of heavy metals into soil, which resulted in the farmland soil being polluted. Considering the spatial variations of grain production, about 13.86% of grain production was affected due to the heavy metal pollution in farmland soil. These results many provide valuable information for agricultural soil management and protection in China.

  18. Impact of Soil Heavy Metal Pollution on Food Safety in China.

    Directory of Open Access Journals (Sweden)

    Xiuying Zhang

    Full Text Available Food safety is a major concern for the Chinese public. This study collected 465 published papers on heavy metal pollution rates (the ratio of the samples exceeding the Grade II limits for Chinese soils, the Soil Environmental Quality Standard-1995 in farmland soil throughout China. The results showed that Cd had the highest pollution rate of 7.75%, followed by Hg, Cu, Ni and Zn, Pb and Cr had the lowest pollution rates at lower than 1%. The total pollution rate in Chinese farmland soil was 10.18%, mainly from Cd, Hg, Cu, and Ni. The human activities of mining and smelting, industry, irrigation by sewage, urban development, and fertilizer application released certain amounts of heavy metals into soil, which resulted in the farmland soil being polluted. Considering the spatial variations of grain production, about 13.86% of grain production was affected due to the heavy metal pollution in farmland soil. These results many provide valuable information for agricultural soil management and protection in China.

  19. Impact of Soil Heavy Metal Pollution on Food Safety in China

    Science.gov (United States)

    Zhang, Xiuying; Zhong, Taiyang; Liu, Lei; Ouyang, Xiaoying

    2015-01-01

    Food safety is a major concern for the Chinese public. This study collected 465 published papers on heavy metal pollution rates (the ratio of the samples exceeding the Grade II limits for Chinese soils, the Soil Environmental Quality Standard-1995) in farmland soil throughout China. The results showed that Cd had the highest pollution rate of 7.75%, followed by Hg, Cu, Ni and Zn, Pb and Cr had the lowest pollution rates at lower than 1%. The total pollution rate in Chinese farmland soil was 10.18%, mainly from Cd, Hg, Cu, and Ni. The human activities of mining and smelting, industry, irrigation by sewage, urban development, and fertilizer application released certain amounts of heavy metals into soil, which resulted in the farmland soil being polluted. Considering the spatial variations of grain production, about 13.86% of grain production was affected due to the heavy metal pollution in farmland soil. These results many provide valuable information for agricultural soil management and protection in China. PMID:26252956

  20. 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.

  1. 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.)

  2. Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia

    International Nuclear Information System (INIS)

    Chouvelon, Tiphaine; Warnau, Michel; Churlaud, Carine; Bustamante, Paco

    2009-01-01

    There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature. - This work reports the first assessment of Hg levels in edible organisms from the New Caledonian lagoon and the associated risk linked to their consumption by Human

  3. Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia

    Energy Technology Data Exchange (ETDEWEB)

    Chouvelon, Tiphaine [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France); Warnau, Michel [International Atomic Energy Agency-Marine Environment Laboratories (IAEA-MEL), 4 Quai Antoine Ier, MC-98000 (Monaco); Churlaud, Carine [Federation de Recherche en Environnement pour le Developpement Durable (FR-EDD), FR CNRS 3097, Centre Commun d' Analyses, 5 Perspectives de l' Ocean, F-17071 La Rochelle Cedex 9 (France); Bustamante, Paco [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France)], E-mail: pbustama@univ-lr.fr

    2009-01-15

    There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature. - This work reports the first assessment of Hg levels in edible organisms from the New Caledonian lagoon and the associated risk linked to their consumption by Human.

  4. Assessment of Metalloid and Metal Contamination in Soils from Hainan, China

    Directory of Open Access Journals (Sweden)

    Xiangjun Liao

    2018-03-01

    Full Text Available The characterization of the concentrations and sources of metals and metalloids in soils is necessary to establish quality standards on a regional level and to assess the potential threat of metals to food safety and human health. A total of 8713 soil samples throughout Hainan Island, China were collected at a density of one sample per 4 km2, and concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn were analyzed. The geometric mean values of the elements were 2.17, 0.60, 26.5, 9.43, 0.033, 8.74, 22.2, 0.26, and 39.6 mg·· kg−1 for As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn, respectively, significantly lower than the background values of Chinese soils with the exception of Se. Principal component analysis (PCA suggested that multiple anthropogenic sources regulated the elemental compositions of the Hainan environment. Coal combustion and mining are important anthropogenic sources of metals for Hainan. The geochemical maps of elements in Hainan soils were produced using the Geographic Information System (GIS method, and several hot-spot areas were identified. The ecological impact of As, Cd, Cu, Cr, Hg, Pb, Ni, and Zn pollution to the soils was extremely “low”.

  5. Earthworm casts as a sampling medium – a case study from highly contaminated Hg roasting site Pšenk (Idrija area, Slovenia

    Directory of Open Access Journals (Sweden)

    Tamara Teršič

    2013-12-01

    Full Text Available In this study an interesting sampling medium - earthworm casts was examined in a highly Hg contaminated area. Enrichment factor (EF has been applied to assess elevated concentrations of analyzed elements in earthworm casts and to determine elevated concentrations of these elements in soils and casts with regard to European average concentrations in topsoil. In a previous study (Teršič & Gosar, 2012 it was shown that Hg contents and dispersion in casts from studied roasting site are comparable to those in soil, which indicates that soil contamination is substantially reflected in contamination of earthworm casts. Therefore the comparison between elemental concentrations in earthworm casts and soil was investigated with the intention to assess the reflection of possible soil contamination in casts. Besides Hg contamination, elevated concentrations of As, Ca, Cd, Mo, Pb and U were also determined in earthworm casts. The calculated EFs show moderate enrichment of casts with Ca, Sr and P and minimal enrichment with Mg, Zn and Cu. Cast, SOM (surface organic matter rich soil layer and soil enrichments with regard to the European averages show extreme enrichment of all studied media with Hg, followed by significant enrichment with Mo and Cd and moderate enrichment with As. Spatial distributions of analyzed elements in casts mostly show similar pattern as in soil, however, because of the different nature of different earthworm species and specific properties of different elements, the data about cast contamination can only serve as an approximate prediction about the dispersion and distribution of contaminant in soil.

  6. 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)

  7. Amazonian former gold mined soils as a source of methylmercury: Evidence from a small scale watershed in French Guiana

    OpenAIRE

    Guedron, Stephane; Grimaldi, Michel; Grimaldi, Catherine; Cossa, Daniel; Tisserand, Delphine; Charlet, Laurent

    2011-01-01

    Total mercury (HgT) and monomethylmercury (MMHg) were investigated in a tropical head watershed (1 km(2)) of French Guiana. The watershed includes a pristine area on the hill slopes and a former gold mined flat in the bottomland. Concentrations of dissolved and particulate HgT and MMHg were measured in rain, throughfall, soil water and at three points along the stream. Samples were taken in-between and during 14 storm events at the beginning and middle of the 2005 and 2006 rainy seasons. Diss...

  8. A reactive transport model for mercury fate in soil--application to different anthropogenic pollution sources.

    Science.gov (United States)

    Leterme, Bertrand; Blanc, Philippe; Jacques, Diederik

    2014-11-01

    Soil systems are a common receptor of anthropogenic mercury (Hg) contamination. Soils play an important role in the containment or dispersion of pollution to surface water, groundwater or the atmosphere. A one-dimensional model for simulating Hg fate and transport for variably saturated and transient flow conditions is presented. The model is developed using the HP1 code, which couples HYDRUS-1D for the water flow and solute transport to PHREEQC for geochemical reactions. The main processes included are Hg aqueous speciation and complexation, sorption to soil organic matter, dissolution of cinnabar and liquid Hg, and Hg reduction and volatilization. Processes such as atmospheric wet and dry deposition, vegetation litter fall and uptake are neglected because they are less relevant in the case of high Hg concentrations resulting from anthropogenic activities. A test case is presented, assuming a hypothetical sandy soil profile and a simulation time frame of 50 years of daily atmospheric inputs. Mercury fate and transport are simulated for three different sources of Hg (cinnabar, residual liquid mercury or aqueous mercuric chloride), as well as for combinations of these sources. Results are presented and discussed with focus on Hg volatilization to the atmosphere, Hg leaching at the bottom of the soil profile and the remaining Hg in or below the initially contaminated soil layer. In the test case, Hg volatilization was negligible because the reduction of Hg(2+) to Hg(0) was inhibited by the low concentration of dissolved Hg. Hg leaching was mainly caused by complexation of Hg(2+) with thiol groups of dissolved organic matter, because in the geochemical model used, this reaction only had a higher equilibrium constant than the sorption reactions. Immobilization of Hg in the initially polluted horizon was enhanced by Hg(2+) sorption onto humic and fulvic acids (which are more abundant than thiols). Potential benefits of the model for risk management and remediation of

  9. 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...

  10. Source identification of soil mercury in the Spanish islands.

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Carbonell, Gregoria; Nanos, Nikos; Gutiérrez, Carmen

    2013-02-01

    This study spatially analysed the relation between mercury (Hg) content in soil and Hg in rock fragment for the purpose of assessing natural soil Hg contribution compared with Hg from human inputs. We present the Hg content of 318 soil and rock fragment samples from 11 islands distributed into two Spanish archipelagos (the volcanic Canary Islands [Canaries] and the Mediterranean Balearic [Balearic] islands). Assumedly both are located far enough away from continental Hg sources to be able to minimise the effects of diffuse pollution. Physical and chemical soil properties were also specified for the samples. Hg contents were significantly greater in the Balearic limestone soils (61 μg kg(-1)) than in the volcanic soils of the Canaries (33 μg kg(-1)). Hg levels were also greater in topsoil than in rocky fragments, especially on the Balearics. The soil-to-rock ratios varied between 1 and 30. Interestingly, the highest topsoil-to-rock Hg ratio (>16 ×) was found in the vicinity of a coal-fired power plant in Majorca, whereas no similar areas in the Canary archipelago were identified.

  11. 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...

  12. Observation of superdeformation in 191Hg

    International Nuclear Information System (INIS)

    Moore, E.F.; Janssens, R.V.F.; Chasman, R.R.

    1989-01-01

    The first observation of superdeformation in the A ≅ 190 mass region is reported. A rotational band of 12 transitions with an average energy spacing of 37 keV, an average moment of inertia of 110 ℎ 2 MeV -1 , and an average quadrupole moment of 18 ± 3 eb has been observed in 191 Hg. These results are in excellent agreement with a calculation that predicts an ellipsoidal axis ratio of 1.65:1 for the superdeformed shape in this nucleus. Evidence for another discrete superdeformed band and superdeformed structures in the quasi-continuum was also found in the data. 19 refs., 6 figs

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. INAA study of Hg, Se, As, and Br irradiation losses from l-cysteine treated and untreated reference materials

    International Nuclear Information System (INIS)

    Anderson, D.L.

    2013-01-01

    U. S. Food and Drug Administration in-house reference material (RM) Cocoa Powder and National Institute of Standards and Technology Standard RMs (SRMs) 1515 apple leaves, 1547 peach leaves, 1571 orchard leaves, 1566a oyster tissue, and 1568a rice flour were co-irradiated together with polyethylene blanks and analyzed for Hg and Se by anticoincidence instrumental neutron activation analysis. The three botanical SRM portions showed a combined Hg recovery of 70 % while the other portions showed a combined Hg recovery of 169 %, indicating that volatile Hg was lost from botanical SRMs and absorbed by the other irradiated portions. Total Hg recovery for all portions was 82 %. Se results showed no evidence of cross-contamination and all results agreed with certified and known values. National Research Council of Canada Certified RMs DOLT-3 dogfish liver, TORT-2 lobster hepatopancreas, and DORM-3 fish protein were separately analyzed either with no treatment or after treatment with l-cysteine solutions followed by drying over magnesium perchlorate. Each set of portions was co-irradiated with polyethylene and treated filter blanks. Analysis of all components of each treated portion irradiation package showed that essentially all Hg was retained within the package. Treated DOLT-3 portions (inorganic Hg content 53 %) showed a tenfold improvement with 99 % Hg retention. Hg retention for DORM-3 (7 % inorganic Hg) was 85 % (a twofold improvement) while retention for TORT-2 (44 % inorganic Hg), was 94 %, similar to that for untreated portions (96 %). Small irradiation losses (≤0.5 %) of volatile species of Se, As, and Br were observed. (author)

  18. Collective dynamics in dense Hg vapour

    International Nuclear Information System (INIS)

    Ishikawa, D; Inui, M; Matsuda, K; Tamura, K; Baron, A Q R; Tsutsui, S; Tanaka, Y; Ishikawa, T

    2004-01-01

    The dynamic structure factor, S(Q,ο), of dense Hg vapour has been measured by high resolution inelastic x-ray scattering for densities of 3.0, 2.1 and 1.0 g cm -3 corresponding to 0.52, 0.36 and 0.17 times the critical density, respectively, and for momentum transfers between 2.0 and 48 nm -1 . Analysis of the longitudinal current-current correlation function in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The ratios of the frequencies were found to be 1.27 at 3.0 g cm -3 , 1.12 at 2.1 g cm -3 and 1.10 at 1.0 g cm -3 . The sound velocity obtained from the present experiments is well reproduced by a wavenumber dependent adiabatic sound velocity, which means that the collective modes remain in the spectra of dense Hg vapour. (letter to the editor)

  19. 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...

  20. [Heavy metal pollution characteristics and ecological risk analysis for soil in Phyllostachys praecox stands of Lin'an].

    Science.gov (United States)

    Fang, Xiao-bo; Shi, Han; Liao, Xin-feng; Lou, Zhong; Zhou, Lyu-yan; Yu, Hai-xia; Yao, Lin; Sun, Li-ping

    2015-06-01

    An investigation was carried out in an attempt to reveal the characteristics of heavy metals contamination in the soils of Phyllostachys praecox forest in Lin' an. Based on the concentrations of Hg, As, Cu, Pb, Zn, Cd, Cr, Ni, Co and Mn in 160 topsoil samples, the pollution status and ecological risks of heavy metals in the soils were assessed by single factor pollution index, Nemerow integrated pollution index and Hankanson potential ecological risk index. The spatial variability of heavy metal concentrations in the soils closely related to the distribution of traffic, industrial and livestock pollution sources. The average concentrations of Hg, As, Cu, Pb, Zn, Cd, Cr, Ni, Co and Mn in the soils were 0.16, 7.41, 34.36, 87.98, 103.98, 0.26, 59.12, 29.56, 11.44 and 350.26 mg · kg(-1), respectively. Pb, Cd, Zn and Cu concentrations were as 2.89, 1.70, 1.12 and 1.12 times as the background values of soil in Zhejiang Province, respectively. But their concentrations were all lower than the threshold values of the National Environmental Quality Standard for Soil (GB 15618-1995). The average single factor pollution index revealed that the level of heavy metal pollution in the soils was in order of Pb>Cd>Cu= Zn>Hg>As>Ni>Co>Cr>Mn. Pb pollution was of moderate level while Cd, Cu and Zn pollutions were slight. There was no soil pollution caused by the other heavy metals. However, the Nemerow integrated pollution index showed that all the 160 soil samples were contaminated by heavy metals to a certain extent. Among total 160 soil samples, slight pollution level, moderate pollution level and heavy pollution level accounted for 55.6%, 29.4% and 15.0%, respectively. The average single factor potential ecological risk index (Er(i)) implied that the potential ecological risk related to Cd reached moderate level, while the others were of slight level. Furthermore, Cd and Hg showed higher potential ecological risk indices which reached up to 256.82 and 187.33 respectively

  1. 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

  2. Characterization of Electronic Materials HgZnSe and HgZnTe Using Innovative and Conventional Techniques

    Science.gov (United States)

    Tanton, George; Kesmodel, Roy; Burden, Judy; Su, Ching-Hua; Cobb, Sharon D.; Lehoczky, S. L.

    2000-01-01

    , obtained by combining results from conventional Hall measurements of the free carrier concentration with Faraday rotation measurements, will also be presented. One example of how this type of information was derived is illustrated in the following figure which shows Faraday rotation vs wavelength modeled for Hg(l-x)ZnxSe at a temperature of 300K and x=0.07. The plasma contribution, total Faraday rotation, and interband contribution to the Faraday rotation, are designated in the Figure as del(p), FR tot, and del(i) respectively. Experimentally measured values of FR tot, each indicated by + , agree acceptably well with the model at the probe wavelength of 10.6 microns. The model shows that at the probe wavelength, practically all the rotation is due to the plasma component, which can be expressed as delta(sub p)= 2pi(e(sup 3))NBL/c(sup 2)nm*(sup 2) omega(sup 2). In this equation, delta(sub p) is the rotation angle due to the free carrier plasma, N is the free carrier concentration, B the magnetic field strength, L the thickness of the sample, n the index of refraction, omega the probe radiation frequency, c the speed of light, e the electron charge, and m* the effective mass. A measurement of N by conventional techniques, combined with a measurement of the Faraday rotation angle allows m* to be accurately determined since it is an inverse square function.

  3. Antagonistic Growth Effects of Mercury and Selenium in Caenorhabditis elegans Are Chemical-Species-Dependent and Do Not Depend on Internal Hg/Se Ratios.

    Science.gov (United States)

    Wyatt, Lauren H; Diringer, Sarah E; Rogers, Laura A; Hsu-Kim, Heileen; Pan, William K; Meyer, Joel N

    2016-03-15

    The relationship between mercury (Hg) and selenium (Se) toxicity is complex, with coexposure reported to reduce, increase, and have no effect on toxicity. Different interactions may be related to chemical compound, but this has not been systematically examined. Our goal was to assess the interactive effects between the two elements on growth in the nematode Caenorhabditis elegans, focusing on inorganic and organic Hg (HgCl2 and MeHgCl) and Se (selenomethionine, sodium selenite, and sodium selenate) compounds. We utilized aqueous Hg/Se dosing molar ratios that were either above, below, or equal to 1 and measured the internal nematode total Hg and Se concentrations for the highest concentrations of each Se compound. Observed interactions were complicated, differed between Se and Hg compounds, and included greater-than-additive, additive, and less-than-additive growth impacts. Biologically significant interactions were only observed when the dosing Se solution concentration was 100-25,000 times greater than the dosing Hg concentration. Mitigation of growth impacts was not predictable on the basis of internal Hg/Se molar ratio; improved growth was observed at some internal Hg/Se molar ratios both above and below 1. These findings suggest that future assessments of the Hg and Se relationship should incorporate chemical compound into the evaluation.

  4. Distribution of total and methylmercury in different ecosystem compartments in the Everglades: Implications for mercury bioaccumulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Guangliang [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, Miami, FL 33199 (United States); Cai Yong [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, Miami, FL 33199 (United States)], E-mail: cai@fiu.edu; Philippi, Thomas [Department of Biological Sciences, Florida International University, Miami, FL 33199 (United States); Kalla, Peter; Scheidt, Daniel [US Environmental Protection Agency, Region 4, Science and Ecosystem Support Division, Athens, GA 30605 (United States); Richards, Jennifer [Department of Biological Sciences, Florida International University, Miami, FL 33199 (United States); Scinto, Leonard [Southeast Environmental Research Center, Florida International University, Miami, FL 33199 (United States); Appleby, Charlie [US Environmental Protection Agency, Region 4, Science and Ecosystem Support Division, Athens, GA 30605 (United States)

    2008-05-15

    We analyzed Hg species distribution patterns among ecosystem compartments in the Everglades at the landscape level in order to explore the implications of Hg distribution for Hg bioaccumulation and to investigate major biogeochemical processes that are pertinent to the observed Hg distribution patterns. At an Everglade-wide scale, THg concentrations were significantly increased in the following order: periphyton < flocculent material (floc) < soil, while relatively high MeHg concentrations were observed in floc and periphyton. Differences in the methylation potential, THg concentration, and MeHg retention capacity could explain the relatively high MeHg concentrations in floc and periphyton. The MeHg/THg ratio was higher for water than for soil, floc, or periphyton probably due to high dissolved organic carbon (DOC) concentrations present in the Everglades. Mosquitofish THg positively correlated with periphyton MeHg and DOC-normalized water MeHg. The relative THg and MeHg distribution patterns among ecosystem compartments favor Hg bioaccumulation in the Everglades. - Mercury bioaccumulation in Florida Everglades is related to the distribution patterns of mercury species among ecosystem compartments.

  5. Distribution of total and methylmercury in different ecosystem compartments in the Everglades: Implications for mercury bioaccumulation

    International Nuclear Information System (INIS)

    Liu Guangliang; Cai Yong; Philippi, Thomas; Kalla, Peter; Scheidt, Daniel; Richards, Jennifer; Scinto, Leonard; Appleby, Charlie

    2008-01-01

    We analyzed Hg species distribution patterns among ecosystem compartments in the Everglades at the landscape level in order to explore the implications of Hg distribution for Hg bioaccumulation and to investigate major biogeochemical processes that are pertinent to the observed Hg distribution patterns. At an Everglade-wide scale, THg concentrations were significantly increased in the following order: periphyton < flocculent material (floc) < soil, while relatively high MeHg concentrations were observed in floc and periphyton. Differences in the methylation potential, THg concentration, and MeHg retention capacity could explain the relatively high MeHg concentrations in floc and periphyton. The MeHg/THg ratio was higher for water than for soil, floc, or periphyton probably due to high dissolved organic carbon (DOC) concentrations present in the Everglades. Mosquitofish THg positively correlated with periphyton MeHg and DOC-normalized water MeHg. The relative THg and MeHg distribution patterns among ecosystem compartments favor Hg bioaccumulation in the Everglades. - Mercury bioaccumulation in Florida Everglades is related to the distribution patterns of mercury species among ecosystem compartments

  6. Application of a mer-lux biosensor for estimating bioavailable mercury in soil

    DEFF Research Database (Denmark)

    Rasmussen, Lasse Dam; Sørensen, S. J.; Turner, R. R.

    2000-01-01

    A previously described bioassay using a mer-lux gene fusion for detection of bioavailable mercury was applied for the estimation of the bioavailable fraction of mercury in soil. The bioavailable fraction is defined here as being part of the water leachable fraction. Due to masking of light emission...... responses. The utility of the mer-lux biosensor assay was tested by relating measurements of bioavailable and total mercury to the response of the soil microbial community to mercury exposure. Two different soil types (an agricultural and a beech forest soil) were spiked with 2.5 µg Hg(II) g-1 in microcosms...... in resistance or diversity. This study showed that the bioassay using the mer-lux biosensor is a useful and sensitive tool for estimation of bioavailable mercury in soil....

  7. Environmental Metabarcoding Reveals Contrasting Belowground and Aboveground Fungal Communities from Poplar at a Hg Phytomanagement Site.

    Science.gov (United States)

    Durand, Alexis; Maillard, François; Foulon, Julie; Gweon, Hyun S; Valot, Benoit; Chalot, Michel

    2017-11-01

    Characterization of microbial communities in stressful conditions at a field level is rather scarce, especially when considering fungal communities from aboveground habitats. We aimed at characterizing fungal communities from different poplar habitats at a Hg-contaminated phytomanagement site by using Illumina-based sequencing, network analysis approach, and direct isolation of Hg-resistant fungal strains. The highest diversity estimated by the Shannon index was found for soil communities, which was negatively affected by soil Hg concentration. Among the significant correlations between soil operational taxonomic units (OTUs) in the co-occurrence network, 80% were negatively correlated revealing dominance of a pattern of mutual exclusion. The fungal communities associated with Populus roots mostly consisted of OTUs from the symbiotic guild, such as members of the Thelephoraceae, thus explaining the lowest diversity found for root communities. Additionally, root communities showed the highest network connectivity index, while rarely detected OTUs from the Glomeromycetes may have a central role in the root network. Unexpectedly high richness and diversity were found for aboveground habitats, compared to the root habitat. The aboveground habitats were dominated by yeasts from the Lalaria, Davidiella, and Bensingtonia genera, not detected in belowground habitats. Leaf and stem habitats were characterized by few dominant OTUs such as those from the Dothideomycete class producing mutual exclusion with other OTUs. Aureobasidium pullulans, one of the dominating OTUs, was further isolated from the leaf habitat, in addition to Nakazawaea populi species, which were found to be Hg resistant. Altogether, these findings will provide an improved point of reference for microbial research on inoculation-based programs of tailings dumps.

  8. Distinct toxicological characteristics and mechanisms of Hg2+ and MeHg in Tetrahymena under low concentration exposure.

    Science.gov (United States)

    Liu, Cheng-Bin; Qu, Guang-Bo; Cao, Meng-Xi; Liang, Yong; Hu, Li-Gang; Shi, Jian-Bo; Cai, Yong; Jiang, Gui-Bin

    2017-12-01

    Inorganic divalent mercury complexes (Hg 2+ ) and monomethylmercury complexes (MeHg) are the main mercury species in aquatic systems and their toxicity to aquatic organisms is of great concern. Tetrahymena is a type of unicellular eukaryotic protozoa located at the bottom of food chain that plays a fundamental role in the biomagnification of mercury. In this work, the dynamic accumulation properties, toxicological characteristics and mechanisms of Hg 2+ and MeHg in five Tetrahymena species were evaluated in detail. The results showed that both Hg 2+ and MeHg were ingested and exhibited inhibitory effects on the proliferation or survival of Tetrahymena species. However, the ingestion rate of MeHg was significantly higher than that of Hg 2+ . The mechanisms responsible for the toxicity of MeHg and Hg 2+ were different, although both chemicals altered mitochondrial membrane potential (MMP). MeHg disrupted the integrity of membranes while Hg 2+ had detrimental effects on Tetrahymena as a result of the increased generation of reactive oxygen species (ROS). In addition, the five Tetrahymena species showed different capacities in accumulating Hg 2+ and MeHg, with T. corlissi exhibiting the highest accumulations. The study also found significant growth-promoting effect on T. corlissi under low concentration exposure (0.003 and 0.01μg Hg/mL (15 and 50nM)), suggesting different effect and mechanism that should be more closely examined when assessing the bioaccumulation and toxicity of mercury in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. 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.

  10. 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.

  11. Spatial and vertical distribution of mercury in upland forest soils across the northeastern United States

    International Nuclear Information System (INIS)

    Richardson, Justin B.; Friedland, Andrew J.; Engerbretson, Teresa R.; Kaste, James M.; Jackson, Brian P.

    2013-01-01

    Assessing current Hg pools in forest soils of the northeastern U.S. is important for monitoring changes in Hg cycling. The forest floor, upper and lower mineral horizons were sampled at 17 long-term upland forest sites across the northeastern U.S. in 2011. Forest floor Hg concentration was similar across the study region (274 ± 13 μg kg −1 ) while Hg amount at northern sites (39 ± 6 g ha −1 ) was significantly greater than at western sites (11 ± 4 g ha −1 ). Forest floor Hg was correlated with soil organic matter, soil pH, latitude and mean annual precipitation and these variables explained approximately 70% of the variability when multiple regressed. Mercury concentration and amount in the lower mineral soil was correlated with Fe, soil organic matter and latitude, corresponding with Bs horizons of Spodosols (Podzols). Our analysis shows the importance of regional and soil properties on Hg accumulation in forest soils. -- Highlights: •Mercury in the forest floor and mineral soil was quantified at 17 sites. •Concentrations and amounts were regressed with regional factors and soil properties. •Forest floor Hg was most explained by soil organic matter, pH, and precipitation. •Mineral soil Hg was explained by latitude, Fe concentration, and soil organic matter. •Mineral soil Hg was greatest in Bs horizons of Spodosols due to podzolization. -- Forest floor Hg was correlated with soil organic matter, pH, latitude, and mean annual precipitation. Mineral soil Hg was greatest in Bs horizons of Spodosols

  12. 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.

  13. Loci and candidate genes conferring resistance to soybean cyst nematode HG type 2.5.7.

    Science.gov (United States)

    Zhao, Xue; Teng, Weili; Li, Yinghui; Liu, Dongyuan; Cao, Guanglu; Li, Dongmei; Qiu, Lijuan; Zheng, Hongkun; Han, Yingpeng; Li, Wenbin

    2017-06-14

    Soybean (Glycine max L. Merr.) cyst nematode (SCN, Heterodera glycines I,) is a major pest of soybean worldwide. The most effective strategy to control this pest involves the use of resistant cultivars. The aim of the present study was to investigate the genome-wide genetic architecture of resistance to SCN HG Type 2.5.7 (race 1) in landrace and elite cultivated soybeans. A total of 200 diverse soybean accessions were screened for resistance to SCN HG Type 2.5.7 and genotyped through sequencing using the Specific Locus Amplified Fragment Sequencing (SLAF-seq) approach with a 6.14-fold average sequencing depth. A total of 33,194 SNPs were identified with minor allele frequencies (MAF) over 4%, covering 97% of all the genotypes. Genome-wide association mapping (GWAS) revealed thirteen SNPs associated with resistance to SCN HG Type 2.5.7. These SNPs were distributed on five chromosomes (Chr), including Chr7, 8, 14, 15 and 18. Four SNPs were novel resistance loci and nine SNPs were located near known QTL. A total of 30 genes were identified as candidate genes underlying SCN resistance. A total of sixteen novel soybean accessions were identified with significant resistance to HG Type 2.5.7. The beneficial alleles and candidate genes identified by GWAS might be valuable for improving marker-assisted breeding efficiency and exploring the molecular mechanisms underlying SCN resistance.

  14. Levels of Cd, Hg and Zn in some surface waters from the Eastern ...

    African Journals Online (AJOL)

    Total trace metals levels - Cd, Hg and Zn, which may affect human health and the "health" of the aquatic ecosystem, were determined in the Umtata, Buffalo, Keiskamma and Tyume Rivers and in the Sandile and Umtata Dams. These elements were also determined in sediment samples from some of these surface waters.

  15. 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.

  16. 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...

  17. 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.

  18. Superdeformation studies in {sup 191}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

    Superdeformation in the A {approximately} 190 region was first observed in {sup 191}Hg from an experiment performed at ATLAS using the Argonne Notre Dame {gamma}-ray facility. We recently revisited the study of superdeformation in this nucleus using Gammasphere and the {sup 160}Gd({sup 36}S,5n) and {sup 174}Yb({sup 22}Ne,5n) reactions at 172 and 120 MeV in order to populate and measure states in the second well. The goal of the experiment was to identify new bands in the data, and thus allow us to gain understanding on the relative placement of single particle orbitals near the N = 112 SD shell gap. From an analysis of the data, the three previously identified SD bands were extended, and their feeding into the yrast states delineated. Two new SD bands were observed and preliminary evidence for a third new band was obtained as well.

  19. Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China

    Science.gov (United States)

    Wang, Lijun; Tao, Wendong; Smardon, Richard C.; Xu, Xue; Lu, Xinwei

    2018-06-01

    Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.

  20. Speciation, sources, and risk assessment of heavy metals in suburban vegetable garden soil in Xianyang City, Northwest China

    Science.gov (United States)

    Wang, Lijun; Tao, Wendong; Smardon, Richard C.; Xu, Xue; Lu, Xinwei

    2017-07-01

    Intensive anthropogenic activities can lead to soil heavy metal contamination resulting in potential risks to the environment and to human health. To reveal the concentrations, speciation, sources, pollution level, and ecological risk of heavy metals in vegetable garden soil, a total of 136 soil samples were collected from three vegetable production fields in the suburbs of Xianyang City, Northwest China. These samples were analyzed by inductively coupled plasma- atomic emission spectrometry and atomic fluorescence spectrometry. The results showed that the mean concentrations of Cd, Co, Cu, Mn, Pb, Zn, and Hg in vegetable garden soil were higher than the corresponding soil element background values of Shaanxi Province. The heavy metals studied in vegetable garden soil were primarily found in the residual fraction, averaging from 31.26% (Pb) to 90.23% (Cr). Considering the non-residual fractions, the mobility or potential risk was in the order of Pb (68.74%)>Co (60.54%)>Mn (59.28%) >Cd (53.54%) ≫Ni (23.36%) >Zn (22.73%)>Cu (14.93%)>V (11.81%)>Cr (9.78%). Cr, Mn, Ni, V, and As in the studied soil were related to soilforming parent materials, while Cu, Hg, Zn, Cd, Co, and Pb were associated with the application of plastic films, fertilizers, and pesticides, as well as traffic emissions and industrial fumes. Cr, Ni, V, and As presented low contamination levels, whereas Co, Cu, Mn, Pb, and Zn levels were moderate, and Cd and Hg were high. Ecological risk was low for Co, Cr, Cu, Mn, Pb, Zn, and As, with high risk observed for Cd and Hg. The overall pollution level and ecological risk of these heavy metals were high.

  1. Greater Fusarium wilt suppression after complex than after simple organic amendments as affected by soil pH, total carbon and ammonia-oxidizing bacteria

    NARCIS (Netherlands)

    Senechkin, I.V.; Overbeek, van L.S.; Bruggen, van A.H.C.

    2014-01-01

    A field experiment was conducted to compare effects of four types of organic amendments on soil chemical, microbiological and disease suppression characteristics in an organic farm. The amendments were plant-derived fresh compost (C), steer-derived slurry (S), slurry plus dung (SD) and slurry,

  2. Soil microbial toxicity of eight polycyclic aromatic compounds: effects on nitrification, the genetic diversity of bacteria, and the total number of protozoans

    DEFF Research Database (Denmark)

    Sverdrup, Line Emilie; Ekelund, Flemming; Krogh, Paul Henning

    2002-01-01

    mg/kg. For effects on nitrification, toxicity (NOEC values) expressed as soil pore-water concentrations (log10(micromol/L)) showed a significant inverse relationship with lipophilicity (log octanol-water partition coefficient) of the substances (r2 = 0.69, p = 0.011, n = 8). This finding could...

  3. Invasive and exotic earthworms: an unaccounted change to mercury cycling in northeastern US forest soils

    Science.gov (United States)

    Richardson, J. B.; Friedland, A. J.; Görres, J. H.; Renock, D. J.; Jackson, B. P.

    2014-12-01

    Invasive and exotic earthworms are now present in many forested areas of the northeastern US with currently unquantified consequences to abiotic and biotic Hg cycling. To quantify these effects, we measured Hg concentrations (mg kg-1) and amounts (μg m-2) in earthworms and soil horizons at 45 soil pits from 9 sites in northern New England. Seven earthworm species were observed in varying assemblages. Most earthworm species attained concentrations of Hg potentially hazardous to wildlife that may ingest them, with highest concentrations found in shallow-burrowing, litter-feeders. Specifically, Aporrectodea rosea and Amynthas agrestis had the greatest Hg concentrations (0.9 ± 0.1) and Hg amounts (8 ± 2) μg m-2. Aporrectodea rosea and Amynthas agrestis were found to inhabit the forest floor and the top 5 cm of the mineral horizons in high abundance, potentially making it a readily accessible prey species. Bioaccumulation of Hg by invasive and exotic earthworms may be an important mechanism that transfers Hg to ground foraging predators, such as thrushes, red-backed salamanders and foxes, which is generally unaccounted for in terrestrial food chains. Earthworm Hg concentrations were poorly correlated with their respective soil Hg concentrations, suggesting a species dependence for Hg bioaccumulation rather than site effects. We observed that forest floor Hg concentrations and amounts were 23% and 57% lower, respectively, at soil pits with earthworms compared to those without. Moreover, Hg amounts in forest floor-feeding earthworms exceeded the remaining forest floor Hg pools. Mercury concentrations and pools in the mineral soil were 21% and 33% lower, respectively, for soil pits with earthworms compared to those without. We hypothesize that enhanced decomposition, horizon disturbance and bioaccumulation by earthworms has decreased Hg amounts in the forest floor and mineral soil. Our results suggest that earthworms are decreasing Hg storage in forest soils with

  4. Identification of the unfavored N=7 superdeformed band in 191Hg

    International Nuclear Information System (INIS)

    Carpenter, M.P.; Janssens, R.V.F.; Cederwall, B.; Crowell, B.; Ahmad, I.; Becker, J.A.; Brinkman, M.J.; Deleplanque, M.A.; Diamond, R.M.; Fallon, P.; Farris, L.P.; Garg, U.; Gassmann, D.; Henry, E.A.; Henry, R.G.; Hughes, J.R.; Khoo, T.L.; Lauritsen, T.; Lee, I.Y.; Machiavelli, A.O.; Moore, E.F.; Nisius, D.; Stephens, F.S.

    1995-01-01

    A new superdeformed band has been identified in 191 Hg bringing the total number of bands observed in this nucleus to four. The new band has properties similar to those of a superdeformed band reported recently in 193 Hg. Both bands are believed to be built on the unfavored signature of the j 15/2 intruder configuration. Comparisons between the data and cranked Woods-Saxon calculations highlight the strengths and weaknesses of theory in describing high-N orbitals at large deformation

  5. Bioindication of total toxicity and teratogenicity of bottom deposits and soils from regions with different degree of the influence of the Chernobyl NPP accident using the developing embryos of grey sea urchins

    International Nuclear Information System (INIS)

    Grishchenko, O.M.; Chumak, V.K.; Grishchenko, S.O.; Rachins'kij, V.N.; Grishchenko, N.O.

    1992-01-01

    The changes (for 1983-90) in total toxicity and teratogenicity of bottom deposits in the Dnieper cascade and soil from some regions of the Ukraine with unequal degree of the influence of the Chernobyl NPP accident have been comparatively studied using developing embryos and larvae of grey sea urchins which are very sensitive to the unfavourable effect of radionuclides, many chemical technogenic factors. (author)

  6. 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

  7. Structural and elastic properties of defect chalcopyrite HgGa{sub 2}S{sub 4} under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gomis, O., E-mail: osgohi@fis.upv.es [Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Santamaría-Pérez, D. [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universitat de València, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 València (Spain); Departamento de Química Física I, Universidad Complutense de Madrid, MALTA Consolider Team, Avenida Complutense s/n, 28040 Madrid (Spain); Vilaplana, R.; Luna, R. [Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Sans, J.A.; Manjón, F.J. [Instituto de Diseño para la Fabricación y Producción Automatizada, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Errandonea, D. [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universitat de València, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 València (Spain); and others

    2014-01-15

    Highlights: • Single crystals of HgGa{sub 2}S{sub 4} with defect-chalcopyrite (DC) structure were synthesized. • High-pressure X-ray diffraction in DC-HgGa{sub 2}S{sub 4} was performed. • Equation of state of DC-HgGa{sub 2}S{sub 4} determined (bulk modulus of 48.4 GPa). • Calculated elastic constants of DC-HgGa{sub 2}S{sub 4} reported at different pressures. • DC-HgGa{sub 2}S{sub 4} becomes mechanically unstable above 13.8 GPa. -- Abstract: In this work, we focus on the study of the structural and elastic properties of mercury digallium sulfide (HgGa{sub 2}S{sub 4}) at high pressures. This compound belongs to the family of AB{sub 2}X{sub 4} ordered-vacancy compounds and exhibits a tetragonal defect chalcopyrite structure. X-ray diffraction measurements at room temperature have been performed under compression up to 15.1 GPa in a diamond anvil cell. Our measurements have been complemented and compared with ab initio total energy calculations. The axial compressibility and the equation of state of the low-pressure phase of HgGa{sub 2}S{sub 4} have been experimentally and theoretically determined and compared to other related ordered-vacancy compounds. The pressure dependence of the theoretical cation–anion and vacancy-anion distances and compressibilities in HgGa{sub 2}S{sub 4} are reported and discussed in comparison to other related ordered-vacancy compounds. Finally, the pressure dependence of the theoretical elastic constants and elastic moduli of HgGa{sub 2}S{sub 4} has been studied. Our calculations indicate that the low-pressure phase of HgGa{sub 2}S{sub 4} becomes mechanically unstable above 13.8 GPa.

  8. Crystal structure of HgGa{sub 2}Se{sub 4} under compression

    Energy Technology Data Exchange (ETDEWEB)

    Gomis, Oscar, E-mail: osgohi@fis.upv.es [Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Vilaplana, Rosario [Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Manjón, Francisco Javier [Instituto de Diseño para la Fabricación y Producción Automatizada, MALTA Consolider Team, Universitat Politècnica de València, 46022 València (Spain); Santamaría-Pérez, David [Departamento de Química Física I, Universidad Complutense de Madrid, MALTA Consolider Team, Avenida Complutense s/n, 28040 Madrid (Spain); Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Errandonea, Daniel [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); and others

    2013-06-01

    Highlights: ► Single crystals of HgGa{sub 2}Se{sub 4} with defect-chalcopyrite structure were synthesized. ► HgGa{sub 2}Se{sub 4} exhibits a phase transition to a disordered rock salt structure at 17 GPa. ► HgGa{sub 2}Se{sub 4} undergoes a phase transition below 2.1 GPa to a disordered zinc blende. - Abstract: We report on high-pressure x-ray diffraction measurements up to 17.2 GPa in mercury digallium selenide (HgGa{sub 2}Se{sub 4}). The equation of state and the axial compressibilities for the low-pressure tetragonal phase have been determined and compared to related compounds. HgGa{sub 2}Se{sub 4} exhibits a phase transition on upstroke toward a disordered rock-salt structure beyond 17 GPa, while on downstroke it undergoes a phase transition below 2.1 GPa to a phase that could be assigned to a metastable zinc-blende structure with a total cation-vacancy disorder. Thermal annealing at low- and high-pressure shows that kinetics plays an important role on pressure-driven transitions.

  9. [The approach to the regulation of mercury according to the content of its termoforms in soils and bed loads].

    Science.gov (United States)

    Bogdanov, N A

    The article contains the results of the ecological and hygienic diagnostics of conditions of lands of areas of different sizes and varying degrees of urbanization, located in different agro-climatic conditions of European Russia (the southern Astrakhan region, he city of Moscow). Assessments of the state of territories use a new approach to rationing of Hg according to quantitative ratios of the content of its thermoforms in soils, grounds and alluvium (in litho substrate). The method of diagnostics is based on known properties of Hg forms: their geochemical activity (migration mobility) and toxicity decline along with the increment of the Hg temperature threshold of the release in the process of continuous warming up of the litho substrate sample (up to 1100°C). Thermoforms are not tied to specific minerals or chemicals and are conditionally designated as FR (Free: 500°C) Hg forms. Among forms, also conditionally according to complexes of low, medium and high temperature variations(FR + CL, FS + CS and SU + IZ, respectively, there are selected groups of «mobile», «sustainable» and «inert» forms. For technogenic Hg there is characterized the predominance in the sample of «mobile» and to lesser extent degree - «stable» thermoforms. The more intensive this predominance is, the higher is environmental hazard. The natural accumulation is diagnosed by the presence and prevalence of the sum of moderate - and high-temperature inert forms of Hg. According to the ratios of Hg content, its forms and groups, as well as the density of correlationships between them, 6 indices of the conditions of soils and alluvium were developed by ourselves.Main coefficients out of indices on informativeness of results of diagnostics are the following factors: Endogenous input, Geochemical activity and Hg mobility. With regard to the combination of variability in indices, the total amount of Hg, the genesis and intensity of its accumulation (natural or anthropogenic), there were

  10. 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

  11. 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.

  12. 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

  13. Determination of the total mercury in contaminated soils by direct solid sampling atomic absorption spectrometry using an AMA-254 device and radiochemical neutron activation analysis

    Czech Academy of Sciences Publication Activity Database

    Sysalová, J.; Kučera, Jan; Fikrle, Marek; Drtinová, B.

    2013-01-01

    Roč. 110, SEP (2013), s. 691-694 ISSN 0026-265X R&D Projects: GA ČR GAP503/12/0682; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 Keywords : Mercury * contaminated soils * AMA-254 * RNAA Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.583, year: 2013

  14. 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.

  15. 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 quantu