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Reduction and methylation of mercury in the terrestrial isopod Porcellio scaber (Crustacea) and its environment
Author(s) -
Nolde Natasa,
Drobne Damjana,
Horvat Milena,
Jereb Vesna
Publication year - 2005
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/04-401r.1
Subject(s) - crustacean , mercury (programming language) , environmental chemistry , methylmercury , zoology , biology , chemistry , ecology , bioaccumulation , computer science , programming language
Reduction and methylation of inorganic mercury in Porcellio scaber (Isopoda, Crustacea) and its environment were studied, using a purpose‐built experimental setup where Hg cycling was followed using 203 Hg 2+ tracer in experiments without and with isopods. In experiment without isopods, daily reduction of 203 Hg 2+ to 203 Hg 0 under sterile and nonsterile conditions was measured for three weeks to assess the contribution of bacteria to this process. In experiments with isopods, daily release of 203 Hg 0 was measured for two weeks. Total mercury (T 203 Hg) and monomethylmercury (Me 203 Hg) in whole animals, gut, digestive glands (hepatopancreas), food (hazelnut leaves), and feces were measured to obtain the assimilation and distribution of mercury in the animals, to investigate the origin and fate of Me 203 Hg, and, finally, to assess the mass balance of mercury in the experimental system. Experiment without isopods showed the important role of bacteria in reduction of 203 Hg 2+ to 203 Hg 0 , especially in the first day of the experiment. Experiments with isopods showed that formation of 203 Hg 0 depended on the 203 Hg 2+ concentration in the food. The contribution of the isopod's digestive flora in reduction of 203 Hg 2+ to 203 Hg 0 was negligible. Approximately 3% of T 203 Hg and 2% of Me 203 Hg consumed was assimilated by the animals. Methylation of 203 Hg 2+ occurred already in the leaves before they were consumed by the isopods. Assimilation of Me 203 Hg from the food surprisingly was low. Also, a loss of Me 203 Hg was noticed when comparing assimilated and excreted Me 203 Hg versus consumed Me 203 Hg. This may be explained by the assumption that demethylation of MeHg prevailed over methylation of Hg 2+ in the animal's digestive system, leading to excretion of ingested mercury as Hg 2+ .