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Transformations of mercury in the terrestrial isopod Porcellio scaber ( Crustacea).The biological cycle of mercury in the terrestrial isopod Porcellio scaber was investigated.
The data obtained show that the percentage of MeHg in leaves, soil and faeces was less than 1%.
This optimised protocol was then applied to Hg transformation studies in the terrestrial isopod P. scaber.
Testing the possibility of in vivo Hg(2+) methylation was divided into two methodologically different parts. Paper-9879657.
All steps of the analytical protocol were checked and optimised by the use of aqueous solutions of 203Hg(2+) and Me(203)Hg(+).
To confirm this assumption, the second methodology was applied-a radiotracer technique with 203Hg(2+) of high specific activity.
Leaching Hg species from P. scaber fed with 203Hg(2+) or Me(203)Hg(+) dosed food was completely efficient only at elevated temperatures.
Additionally, an assessment of the mass balance of Hg in isopods P. scaber exposed to 203Hg(2+) indicates that volatile Hg species are also formed.
Preliminary results of methylation/demethlytion studies are rather variable but they show that both processes (Hg(2+)<-->MeHg(+)) take place in the isopod P. scaber.
Firstly, concentrations of total mercury and MeHg in isopods P. scaber and their environment from a Hg-unpolluted area were measured by the use of validated methods (CV AAS, CV AFS). Paper-9879657.
In contrast, the percentage of MeHg in gut and hepatopancreas was increased to 14 and 77%, respectively, indicating methylation of Hg(2+) in the gut and its further accumulation in glands. Paper-9879657.
The most important finding was that cleaning-up the extract through a florisil column is not appropriate, because the column retains different percentages of Hg(2+) and MeHg(+) and consequently affects the accuracy of the final result. Paper-9879657.
There are few radiotracer techniques for Hg-methylation assays; for our work we chose the method of Czuba et al. which includes alkaline leaching of Hg species, their extraction into dithizone-toluene, followed by specific separation of Hg dithizonates by thin-layer chromatography and gamma counting.
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