| 1. |
- Mellerowicz, Ewa
(författare)
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Pb induces plant cell wall modifications - in particular - the increase of pectins able to bind metal ions level
- 2013
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Ingår i: E3S web of conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 1
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Konferensbidrag (refereegranskat)abstract
- Low - methylesterified pectin fraction, able to bind metal ions, is the cell wall compound which participates in land and water plant cell response to toxic metals. Protonemata of Funaria hygrometrica (Hedw.), root tips of Populus tremula x P.tremuloides and Lemna trisulca fronds, were used for studying the effects of Pb on plants cell walls (CW). The study were focused on the low-methylesterified pectins level and distribution. It was carried out by immunocytochemical methods, using JIM5 antibody which recognized low-methylesterified pectins fraction - up 40%. Pb exposure resulted in the cell wall modifications in all investigated objects. The most striking result was the marked increase of the low-methylesterified pectins level. Moreover, cell walls thickenings were formed both in the moss protonemata and the poplar roots. The cell wall thickenings in both objects contained especially high level of low-methylesterified pectins. Simultaneously, cell wall thickenings accumulated extremely large and numerous Pb deposits. In many regions of the cell wall and cell wall thickenings the colocalization of low-methylesterified pectins and Pb deposits occurred. Low -methylesterified pectins level increased also in the cell walls of Lemna trisulca fronds and some of Pb deposits were colocalized with this pectin fraction in the CW. In fronds several Pb deposits occurred between plasma membrane and cell wall and only occasionally they were colocalized with low-methylesterified pectins. However, in L. trisulca - cell wall was generally thicker in response to Pb. We did not observed almost any local cell wall thickenings as in Funaria and Populus. Taken these facts together we can conclude that plant cell walls were actively and intensively modified in response to Pb. In particular, the amount of low-methylesterified pectins, able to bind toxic Pb ions, markedly increased. Simultaneously, both cell wall and cell wall thickenings were the compartments which accumulate large amount of Pb. Hence, modified cell walls appear to be a very important repository for Pb2+ in different types of plant cells and different species. Detection of such a reaction in three different plant species and three different types of plant cells indicates that it may be more common plant tolerance strategy to Pb.
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| 2. |
- Nerentorp, Michelle, 1986, et al.
(författare)
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Comparison of two measurement methods of dissolved gaseous mercury concentrations and estimations of supersaturation grade and mercury fluxes during a research campaign at the Mediterranean Sea
- 2013
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Ingår i: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 1
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Konferensbidrag (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations were measured during an oceanographic campaign in the Mediterranean Sea. The DGM concentrations were measured using two different methods, a manual-and an automated method. The manual method was used to obtain DGM depth profiles at several stations throughout the campaign. The automated device measured DGM concentrations continuously at a depth of 4 m. Gaseous elemental mercury (GEM) concentrations in air were measured continuously at the bridge deck. The objectives were to achieve DGM depth profiles, compare the manual-and automated DGM measurement methods, to calculate the supersaturation grades of the sea and the evasional fluxes from the sea surface. Depth profiles of the four measured stations show no diurnal variations. The manual-and the automated method show good compliance. Supersaturation grades are high due to high DGM values and low GEM concentrations. Fluxes of Hg from the sea surface are more dependent on the wind speed than on the supersaturation grade according to the flux models used.
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| 3. |
- Nerentorp, Michelle, 1986, et al.
(författare)
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Speciation measurements of airborne mercury species in northern Finland; Evidence for long range transport of air masses depleted in mercury
- 2013
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Ingår i: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 1
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Konferensbidrag (refereegranskat)abstract
- Mercury speciation measurements were performed at the Arctic measurement site, Pallas Matorova, in northern Finland during the period 12-04-02 to 12-04-26. For the first time Hg speciation measurements with high sensitivity and temporal resolution were performed at this site. The measurement allowed simultaneous determination of TGM, GEM, GOM and particulate bound mercury. Evidence for long range transport of air masses depleted in mercury is provided as well as a study of possible mercury sources determining the temporal variations in airborne mercury species at the site.
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| 4. |
- Slemr, F., et al.
(författare)
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CARIBIC observations of gaseous mercury in the upper troposphere and lower stratosphere
- 2013
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Ingår i: Proceedings of the 16th International Conference on Heavy Metals in the Environment. - : EDP Sciences. - 2100-014X. ; 1
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Konferensbidrag (refereegranskat)abstract
- A unique set of gaseous mercury measurements in the upper troposphere and lower stratosphere (UT/LS) has been obtained during the monthly CARIBIC (www.caribic-atmospheric.com) flights since May 2005. The passenger Airbus 340-600 of Lufthansa covered routes to the Far East, North America, India, and the southern hemisphere. The accompanying measurements of CO, O3, NOy, H2O, aerosols, halocarbons, hydrocarbons, greenhouse gases, and several other parameters as well as backward trajectories enable a detailed analysis of these measurements. Speciation tests have shown that the CARIBIC measurements represent a good approximation of total gaseous mercury (TGM) concentrations. Above the tropopause TGM always decrease with increasing potential vorticity (PV) and O3 which implies its conversion to particle bound mercury. The observation of the lowest TGM concentrations at the highest particle concentrations in the stratosphere provides further evidence for such conversion. We will show how a seasonally dependent conversion rate could be derived using concomitantly measured SF6 mixing ratios as a timer. Tropospheric mercury data suggest the existence of a decreasing trend in the northern hemisphere whose size is comparable with the trend derived from long-term measurements by ship cruises, at Cape Point (South Africa) and Mace Head (Ireland).
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