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  • 1
    Electronic Resource
    Electronic Resource
    Subnanogram determination of mercury by two-stage gold amalgamation and gas phase detection applied to atmospheric analysis (1979)
    s.l. : American Chemical Society
    Analytical chemistry 51 (1979), S. 1714-1720 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50047a030
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  • 2
    Electronic Resource
    Electronic Resource
    Cold-trap preconcentration method for the determination of mercury in sea water and in other natural materials (1974)
    s.l. : American Chemical Society
    Analytical chemistry 46 (1974), S. 1882-1885 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60349a002
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  • 3
    Electronic Resource
    Electronic Resource
    Variations in mercury deposition to Antarctica over the past 34,000 years (1993)
    [s.l.] : Nature Publishing Group
    Nature 362 (1993), S. 621-623 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The historical record of mercury deposition contained in polar ice cores yields information on the natural biogeochemical mercury cycle and provides a way to assess the impact of modern anthropogenic emissions. The atmosphere is one main pathway for the distribution of mercury at the Earth's ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/362621a0
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  • 4
    Electronic Resource
    Electronic Resource
    A preliminary mercury budget for Narragansett Bay (Rhode Island, USA) (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 679-682 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The distribution of total Hg (Hgt) and reactive (HgR) in Narragansett Bay, fresh water tributaries and point source discharges was determined during a synoptic survey, carried out in April, 1986. A Hg budget which includes fluvial inputs and atmospheric Hg deposition was constructed and the estuarine behavior of Hg assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189720
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  • 5
    Electronic Resource
    Electronic Resource
    Modeling the elemental mercury cycle in Pallette Lake, Wisconsin, USA (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 529-538 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The spatial and temporal distribution of elemental Hg (Hg°) and reactive Hg (HgR) has been studied on Pallette Lake, Wisconsin during May – August, 1993 and May, 1994. In general, Hg° concentrations near the lake surface greatly exceeded saturation with respect to atmospheric Hg° indicating a flux out (−) of the lake. Evasional losses were estimated using a thin film model and averaged −101 pmol m−2 d−1 during July and August, 1993. A large portion of atmospherically deposited Hg is re-emitted. Thus, in-lake Hg° production' and evasion to the atmosphere will significantly reduce the amount of Hg which is transported to the sediments, the principal site of methylation. Laboratory experiments were conducted to ascertain the rate of Hg° formation from Hg(II). Reduction was significantly lower in heat sterilized lakewater suggesting Hg° production was biologically mediated. The temporal distribution of epilimnetic Hg°, as measured at the lake center, was influenced by Hg° evasion, Hg° production and advective transport of water parcels of differing Hg content. Spatial gradients in Hg° and HgR were identified and a transport model was employed to estimate the advective flux of Hg°. The importance of atmospheric deposition and sediment-water interaction as sources of HgR to epilimnetic waters were examined. Porewater concentrations of Hg° and HgR were determined on several occasions. During May, 1994, the depletion of lakewater HgR following a input pulse due to rain was observed and the estimated removal rate (16–20% d−1) agrees well with reduction rates obtained in the laboratory (23% d−1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189703
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  • 6
    Electronic Resource
    Electronic Resource
    Atmospheric cycling and air-water exchange of mercury over mid-continental lacustrine regions (1991)
    Springer
    Water, air & soil pollution 56 (1991), S. 745-767 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Atmospheric mobilization and exchange at the air-water interface are significant features of biogeochemical cycling of Hg at the Earth's surface. Our marine studies of Hg have been extended to terrestrial aquatic systems, where we are investigating the tropospheric cycling, deposition and air-water exchange of Hg in the mid-continental lacustrine environs of northcentral Wisconsin. This program is part of a multidisciplinary examination into the processes regulating the aquatic biogeochemistry of Hg in temperate regions. Trace-metal-free methodologies are employed to determine Hg and alkylated Hg species at the picomolar level in air, water and precipitation. We have found Hg concentrations and atmospheric fluxes in these fresh water systems to be similar to open ocean regions of the Northern Hemisphere. A well constrained mass balance for Hg has been developed for one of the lakes, Little Rock Lake, which is an extensively studied clear water seepage lake that has been divided with a sea curtain into two basins, one of which is untreated (reference pH: 6.1) while the other is being experimentally acidified (current pH: 4.7). This budget shows that the measured total atmospheric Hg deposition (ca. 10 µg m−2 yr−1) readily accounts for the total mass of Hg in fish, water and accumulating in the sediments of Little Rock Lake. This analysis demonstrates the importance of atmospheric Hg depositional fluxes to the geochemical cycling and bioaccumulation of Hg in temperate lakes. It further suggests that modest increases in atmospheric Hg loading could lead directly to enhanced levels of Hg in biota. Analogous modeling for monomethylmercury (MMHg) is as yet limited. Nevertheless, preliminary data for the atmospheric deposition of MMHg indicate that this flux is insufficient. to account for the amounts of MMHg observed in biota. An in-lake synthesis of MMHg is implicated. The importance of volatile Hg which is principally in the elemental form, and its evasion to the atmosphere is also illustrated. We suggest that the in-lake production of Hg° can reduce the Hg (II) substrate used in the in-lake microbiological synthesis of MMHg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342314
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  • 7
    Electronic Resource
    Electronic Resource
    Cycling of volatile mercury in temperate lakes (1991)
    Springer
    Water, air & soil pollution 56 (1991), S. 791-803 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The cycling of dissolved gaseous Hg (DGM) has been examined in our studies of the troposphericHg cycle, air-water exchange and their importance to the biogeochemical behavior and fate of Hg in temperate lakes. Five seepage lakes in northcentral Wisconsin, ranging in pH from 4.7 to 7.2, have been studied under a variety of limnological conditions which included the following seasonal periods: summer (peak stratification), fall (following turnover) and late winter (under ice). Analytically, DGM was determined after purging lake water with argon and collecting the volatile Hg fraction on gold coated sand. The Hg collections were analysed by pyrolysis in a two-stage Au amalgamation gas train with detection by atomic fluorescence spectroscopy (AFS). In addition, chemical speciation of the volatile fraction has been achieved by trapping on a nondestructive substrate followed by gas chromatographic separation and AFS detection. The DGM consists principally of elemental Hg (Hgo) under all sampling conditions, with no significant contribution from volatile organic Hg species (detection limit of 3 femtomolar). Atmospheric gaseous Hg, which also consists principally of Hgo, was measured and the air-water partitioning determined. In general, the lake waters have been supersaturated with Hgo relative to the atmosphere. Supersaturation was greater in the summer, ranging from ca. 1.4 to 12 times (x) the saturation concentration. During the other sampling periods, Hgo ranged from saturation to ca. 7x the equilibrium concentration. The flux of Hg from the lakes due to gas evasion is significant and is estimated at approximately 10% of the annual atmospheric input of Hg to the lakes. An apparent relationship between Hgo and pH has been observed with lakes of lower pH having smaller Hgo concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342317
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  • 8
    Electronic Resource
    Electronic Resource
    Atmospheric mercury in northern Wisconsin: Sources and species (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 189-198 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The atmospheric chemistry, deposition and transport of mercury (Hg) in the Upper Great Lakes region is being investigated at a near-remote sampling location in northern Wisconsin. Intensive sampling over two years and various seasons has been completed. A multi-phase collection strategy (gas-, particle- and precipitation-phases) was employed to gain insight into the processes controlling concentrations and chemical/physical speciation of atmospheric Hg. Additional chemical and physical atmospheric determinations (e.g. ozone, particulate constituents, meteorology) were also made during these periods to aid in the interpretation of the Hg determinations. For example, correlations of Hg with ozone, sulfur dioxide and synopticscale meteorological features suggest a regionally discernible signal in Hg. Comparison to isosigma backward air parcel trajectories confirms this regionality and implicates the areas south, southeast and northwest of the site to be sources for Hg. Particle-phase Hg (Hgp) was found to be approximately 40% in an oxidized form, or operationally defined as “reactive”. However, this was quite variable from year-to-year. Hgp and other particle constituents (esp. sulfate) show significant correlation and similarity in behavior (concentration ratios in precipitation and in particles). These observations are part of the growing evidence to support the hypothesis that precipitation-phase Hg arises in large part from the scavenging of atmospheric particulates bearing Hg. Observed concentrations of rain and particle-Hg fit broadly the theoretical expectations for nucleation and below-cloud scavenging. Significant increases in the Hg/aerosol mass ratio appear to take place during transport. Enrichment of aerosols is taken as evidence of gas/particle conversion which could represent the step linking gas-phase Hg with rain. The refined budget indicates ca. 24% of total deposition is from summer particle dry deposition, and that this deposition also contributes ca. 24% of all reactive Hg deposition. Additionally, almost all (86%) deposition (wet and dry) occurs during the summer months.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189667
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  • 9
    Electronic Resource
    Electronic Resource
    Is mercury increasing in the atmosphere? The need for an atmospheric mercury network (AMNET) (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 245-254 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Mercury uses in human endeavors will lead to a general, though variable, volatilization of Hg. Current estimates for anthropogenic interferences range from about 50 to 75% of the total annual Hg emissions to the atmosphere. Recent modeling suggests that the present atmospheric Hg burden has increased by a factor of 3 during the last 100 years with a current rate of increase of about 0.6% yr−1 (ca. 0.01ng m−3yr−1). This impact, which is significant, can be examined and assessed empirically. To date, however, atmospheric Hg programs have not employed an experimental design sufficient to account for short time scale atmospheric Hg variations of natural and anthropogenic origin, and to resolve the long term temporal pattern. I am proposing an international research program, AMNET, or Atmospheric Hg Network, to address the important question, “Is Hg increasing in the atmosphere?” AMNET would examine temporal and spatial variations in atmospheric Hg and assess the influence of natural and anthropogenic sources on the global atmospheric Hg cycle. This program requires international support and cooperation. The experimental design of AMNET would follow the successful Atmospheric Lifetime Experiment Program (ALE), which examined the contemporary temporal changes in the atmospheric concentrations of the freons, methyl chloroform, carbon tetrachloride, and nitrous oxide. Following the ALE design, AMNET sampling stations would be maintained in both hemispheres and at sites free from strong local pollution sources of Hg (e.g., remote islands). Measurements would be made for a period of three to five years. The precision and accuracy of the Hg0 determinations must be ≥ 1%. The accurate resolution of the variability and secular trends in the atmospheric Hg burden can provide: (1) a direct quantitative assessment of the scale to which anthropogenic processes are affecting the natural biogeochemical cycling of Hg; (2) an essential refinement and constraint currently lacking in mass balance models; (3) an enhanced knowledge of the behavior of Hg in the atmosphere, and (4) an accurate data base required for global circulation atmospheric chemical Hg models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189674
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  • 10
    Electronic Resource
    Electronic Resource
    An Examination of the Atmospheric Chemistry of Mercury Using 210Pb and 7Be (2000)
    Springer
    Journal of atmospheric chemistry 36 (2000), S. 325-338 
    Details
    ISSN: 1573-0662
    Keywords: atmospheric mercury ; radiotracers ; deposition ; gas-to-particle conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Measurements of Hg (total gas-phase, precipitation-phase andparticulate-phase), aerosol mass, particulate 210Pb and7Be and precipitation 210Pb were made at an atmosphericcollection station located in a near remote area of northcentral Wisconsin,U.S.A. (46°10′N, 89°50′W) during the summers of 1993, 1994and 1995. Total Hg and 210Pb were observed to correlate strongly(slope = 0.06 ± 0.03 ng mBq-1; r 2 =0.72) in rainwater. Mercury to 210Pb ratios in particulate matter(0.03 ± 0.02 ng mBq-1; r 2 = 0.06) wereconsistent with the ratio in rain. Enrichment of the Hg/mass ratio (approx.5–50×) relative to soil and primary pollutant aerosols indicatedthat gas-to-particle conversion had taken place during transport. Comparisonof these results with models for the incorporation of Hg into precipitationindicates that atmospheric particles deliver more Hg to precipitation than canbe explained by the presence of soot. A lack of correlation between totalgas-phase Hg (TGM) and a 7Be/210Pb function suggests novertical concentration gradient within the troposphere, and allows an estimateof TGM residence time of 1.5 ± 0.6 yr be made based on surface airsamples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006393321473
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