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  • 1
    Electronic Resource
    Electronic Resource
    Xylem sap as a pathway for total mercury and methylmercury transport from soils to tree canopy in the boreal forest (1998)
    Springer
    Biogeochemistry 40 (1998), S. 101-113 
    Details
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; litterfall ; mercury ; methylmercury ; xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Conifer needles are an important link in the cycling of Total Mercury (THg) and Methylmercury (MeHg) in the boreal ecosystem due to the high THg and MeHg concentrations in litterfall. Translocation within the tree of Hg from soils to the crown canopy has been assumed to be a minor source of the Hg in litterfall. This paper, however, is the first to present direct observations of THg/MeHg transport from the soil via xylem sap. Xylem sap concentrations of THg and MeHg were measured in sap drained from different levels along the boles of freshly cut 100 year old Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). The trees came from a mixed stand growing on podzolized till soils at the Svartberget Forest Research Station in N. Sweden. Soil solution concentrations of THg and MeHg at different levels in the soil profile were measured for comparison. Concentrations of THg in xylem sap ranged from 10–15 ng L-1 in both the Scots pine and Norway spruce. Concentrations of MeHg varied from 0.03 ng L-1to 0.16 ng L-1, with higher values in Scots pine than Norway spruce. If these concentrations are representative of the transport from soils to needles in xylem sap at this site, then only 3% of the MeHg in litterfall (0.12 mg ha-1 yr-1) and 11% of the THg (26 mg ha-1 yr-1) can originate via this pathway. The upward transport via xylem sap is larger relative to the open field inputs (84% of THg and 17% of MeHg). Comparison of soil solution and xylem sap THg/MeHg suggested some degree of THg exclusion during water uptake in Scots pine and Norway spruce, but MeHg exclusion only in Norway spruce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005983932240
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  • 2
    Electronic Resource
    Electronic Resource
    The slope of Gran's plot: A useful function in the examination of precipitation, the water-soluble part of airborne particles, and lake water (1978)
    Springer
    Water, air & soil pollution 10 (1978), S. 457-469 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In order to find out how much information could be obtained from an acid-base titration by using the slope of Gran's plot, the titration technique was refined and applied to samples of precipitation, leaching solutions of airborne particles, and lake water. The results indicate a possibility in certain cases to determine, out of an accurate measurement of the slope of the plot, the dissociation constant and concentration of the acids present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250011
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of methylmercury and mercury in run-off, lake and rain waters (1991)
    Springer
    Water, air & soil pollution 56 (1991), S. 309-321 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract During one year, samples from eight drainage lakes, seven run-off stations and three deposition sites from various geographical areas in Sweden were collected and analyzed for methyl Hg (MeHg) and total Hg (Hg-tot). The MeHg concentrations ranged from 0.04 to 0.64 ng L−1, 0.04 to 0.8 ng L−1, and 〈0.05 to 0.6 ng L−1 in run-off, lake water and rain water, respectively. The corresponding Hg-tot concentrations were found in the range 2 to 12 ng L−1, 1.35 to 15 ng L−1, and 7 to 90 ng L−1, respectively. A Hg-tot level of about 60 ng Hg L−1 was found in throughfall water. The MeHg and Hg-tot concentrations are positively correlated in both run-off and lake water, but not in rain and throughfall water. A strong positive correlation between the MeHg, as well as the Hg-tot concentration, and the water color is observed in both run-off and lake waters, which suggests that the transport of MeHg and other Hg fractions from soil via run-off water to the lake is closely related to the transport of organic substances; and is a consequence of the biogeochemical processes and the water flow pathway. The ratio between the mean values of MeHg and Hg-tot seems to be an important parameter, with an indicated negative coupling to the mean value of pH for run-off water, but a strong positive correlation to Hg-content in fish, the ratio between the area of the catchment and the lake, as well as to the retention time of lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342279
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  • 4
    Electronic Resource
    Electronic Resource
    Methylmercury in runoff from the Svartberget Catchment in northern Sweden during a stormflow episode (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 221-224 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The dynamics of MeHg during rain-driven runoff episodes are important in calculating the output of MeHg from forested catchments. These dynamics may also provide insight into the processes controlling MeHg output from soils to surface waters. The concentrations of MeHg, Hg-tot, TOC and associated chemistry were observed during a rain-driven, July runoff episode on two forested tributaries of the Svartberget Catchment, as well as at the outlet of a mire in the headwaters of that catchment. TOC concentrations in runoff increased during the episode. Hg-tot concentrations also tended to increase (from 3 to between 4 and 7 ng L−1), though the timing of that increase varied. MeHg concentrations, on the other hand, tended to decrease. The decrease was slight in the two forested tributaries (ca. 0.1 ng L−1), but greater in the mire runoff (from 0.8 to ca 0.3 ng L−1). These data are set in relation to a hypothesis about the processes which control MeHg output.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189671
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  • 5
    Electronic Resource
    Electronic Resource
    Terrestrial sources of methylmercury in surface waters: The importance of the riparian zone on the Svartberget Catchment (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 435-444 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The runoff of methylmercury (MeHg) from forested catchments to surface waters has been identified as a potentially significant input of MeHg to the aquatic ecosystem. Little, however, is known of the processes which control the transfer of MeHg from soils to surface waters. This study investigated the potential terrestrial sources of MeHg in runoff by sampling profiles of soil solution chemistry and determining the flux of water through those profiles into two tributaries on the Svartberget Catchment in northern Sweden. One study profile was from the podzol soil that covers most of the catchment area. The other profiles were taken in the riparian zone of each of the two tributaries. Soil solution was extracted from the soils by centrifugation. High catchment soil solution concentrations of MeHg (〉1 ng l−1) occur in the surface layers of the soil, but overland flow on the catchment is rare. MeHg concentrations in the podzol profile dropped to less than 0.2 ng l−1 in the mineral soil just 5 cm below the mor layer. In the riparian soil profiles sampled in October, MeHg concentrations were higher (ca. 0.4 ng l−1), but in a July sampling the concentrations in the riparian profiles were comparable to those in the podzol (i.e. 〈 0.2 ng l−1). Very high concentrations of MeHg were found in the streambank sphagnum mosses (〉2 ng l−1) partially submerged within the stream. The concentrations of MeHg observed under the podzol soil were insufficient to sustain the concentration of MeHg in runoff from the forested subcatchments where podzol profiles cover more than 70% of the surface area. The only sources of additional MeHg that lie along major runoff flow pathways are the riparian soils and mosses on the streambanks. It is therefore hypothesized that output of MeHg from the forest areas of the catchment is controlled by the biogeochemical processes in the riparian zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189693
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  • 6
    Electronic Resource
    Electronic Resource
    Trends of mercury and methylmercury in deposition, run-off water and sediments in relation to experimental manipulations and acidification (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 743-748 
    Details
    ISSN: 1573-2932
    Keywords: Mercury ; methylmercury ; sediments ; catchments ; deposition ; trends ; throughfall ; precipitation ; run-off
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In the covered catchment at Lake Gårdsjön, the reversibility of acidification and the effects on Hg output of a decreased deposition of Hg and MeHg have been investigated since 1991. A first indication of a decreased from the covered catchment, caused by the artificial removal of Hg and MeHg input, has been observed. This has occurred in parallel with an overall decrease in Hg deposition fluxes in SW Sweden during 1990 to 1993. In the sediments of two acidified lakes, Lake Gårdsjön (limed) and Lake Härsevatten (acid), Hg concentrations decrease by 60% in the top cm, from the maximum around 1000 ng g−1 at 5 cm depth indicating a decreasing deposition during the last 10 years. This decrease has occurred in parallel with decreasing atmospheric S-levels and is most likely caused by decreasing European Hg emissions. Decreasing trends of MeHg in run-off from two catchments has also been observed while the Hg output has remained somewhat more stable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00476918
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  • 7
    Electronic Resource
    Electronic Resource
    Relations between organic carbon and methylmercury in humic rich surface waters from Svartberget catchment in northern Sweden (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 971-979 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Monthly sampling of a mire outlet and two tributaries, one of them originating in the mire, on the Svartberget catchment in northern Sweden was performed during one year. The concentration of total organic carbon (TOC) in the three waters was fairly high (10–40 mg/l). Methylmercury (MeHg) was analysed in the original water sample (MeHg-whl) and in the humic fraction (MeHg-hum). The MeHg-hum increased with increasing concentration of humic substances (HS; measured as absorbance at 254 nm) in the water. A seasonal variation of the MeHg-hum/TOC ratio was superimposed on a negative relationship to the water flow, which indicates that the methylation is a slow process which results in a rapid drainage of the storage during periods of high flow. A minimum of the MeHg-whl/TOC ratio observed during the spring flood was followed by a slow increase during the rest of the year.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189751
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  • 8
    Electronic Resource
    Electronic Resource
    Methylmercury output from the Svartberget Catchment in northern Sweden during spring flood (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 445-454 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The problem of mercury (Hg) accumulation in the aquatic food chain is widespread in Sweden. The methylmercury (MeHg) in runoff from catchments may be an important component of the MeHg load in surface waters. The spring flood in northern Sweden constitutes a major portion of the annual catchment runoff. This brief, but large event, therefore, may be of significance for the annual output of MeHg from soils to surface waters in this region. Methylmercury, total mercury (Hg-tot) and other chemical parameters were measured in spring flood runoff during April and May 1993 from two tributaries as well as the headwater mire of the 50 ha Svartberget Catchment. Snow cores from April 1993 and April 1994 prior to the onset of spring snowmelt were also analyzed. Stable isotope techniques were used to estimate the proportion of snowmelt in runoff. During the spring flood, Hg-tot and TOC were diluted in output from the headwater mire compared to the concentrations observed prior to the flood. Over half of the runoff from the mire was snowmelt according to the isotope Hydrograph separation. In runoff from the two forested tributaries, however, TOC and Hg-tot concentrations increased. About a third of this runoff was snowmelt. MeHg concentrations in the spring flood declined at all locations to the lowest levels recorded during 1993 (〈0.2 ng l−1). The runoff concentrations of MeHg were less than the average snow core concentration of 0.3 4+/- 0.17 ng l−1. The differences in MeHg dynamics in comparison to TOC or Hg-tot suggest that there are factors independent of the availability of Hg-tot or TOC, and even contemporary MeHg deposition (in this case the snowpack MeHg concentrations) which determine the concentrations and output of MeHg during spring flood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189694
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  • 9
    Electronic Resource
    Electronic Resource
    Catalytic effect of various metal ions on the methylation of mercury in the presence of humic substances (1985)
    Springer
    Water, air & soil pollution 25 (1985), S. 391-400 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Methylation of Hg2+ (Hg(NO3)2) in the presence of fulvic acid (FA) and various metal ions has been studied. The concentrations of Hg2+ and FA ranged from 5 to 20 mg L−1 and 171 to 285 mg L−1 DOC, respectively. The pH range was 3 to 6.5. FA was isolated from an acid brown-water lake by XAD-8 polymeric adsorbent. Methylmercury production in the dark during 2 to 4 days incubation at 30 °C increased with increasing concentrations of Hg2+ ion and FA as well as with additions of metal ions (5 to 10 × 10−5 mole L−1 The observed catalytic activity of metal ions followed the order Fe3+ (Fe2+) 〉 Cu2+ ≈ Mn2+, 〉 Al3+. The production of methylmercury had a pH-optimum around 4 to 4.5 at the conditions tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283791
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  • 10
    Electronic Resource
    Electronic Resource
    Experiences with the analytical procedures for the determination of methylmercury in environmental samples (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 659-664 
    Details
    ISSN: 0268-2605
    Keywords: Methylmercury ; derivatization ; ethylation ; gas chromatography ; digestion ; sediment ; natural water ; cold vapour ; atomic fluorescence spectroscopy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical method using ethylation, gas chromatography-cold vapor atomic fluorescence spectroscopy (GC-CV AFS), combined with different pretreatment procedures, has been used for the determination of methylmercury (MeHg) in various aqueous and solid environmental samples. Different types of samples with varying matrices and MeHg concentration levels require different pretreatment procedures in order to isolate/separate MeHg from the sample matrix, and to overcome interferences in the ethylation reaction process. Limitations of different pretreatment procedures (solvent extraction into methylene chloride, distillation under nitrogen flow and alkaline digestion) are discussed and recommendations are given. The influence of the quality of the ethylating reagent on the analytical results is also examined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590080717
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