COMBINED EFFECTS OF WATER PH AND SALINITY ON THE BIOACCUMULATION OF INORGANIC MERCURY AND METHYLMERCURY IN THE SHORE GRAB CARCINUS-MAENAS

Tissue mercury concentrations were analysed in the whole organism and various organs of the euryhaline shore crab Carcinus maenas after 3 an d 15 days of explosive to inorganic mercury (Hg(II)) and methylmercury (MeHg) at a nominal concentration of 1 mu gHg l(-1). Chemical speciat ion of the metals was varied by using four pH/salinity conditions (com binations between pH 7.0 and 8.5/salinity 560 and 140 mM Nacl). In all conditions, the results showed a particularly important Hg accumulati on in gill tissue, smaller levels in the carapace and internal organs, and very low concentrations in circulating haemolymph. For Hg(II), ac cumulation was generally favoured at low salinity, but the data reveal ed complex pH/salinity interactions. Positive correlations were found between tissue metal levels and the abundance of some inorganic Hg spe cies: HgCl2, HgCl3-, Hg2+, HgCl+, indicating that chemical speciation may be an important factor governing metal uptake, The balance of evid ence favours HgCl2 and CH3HgCl as the most bioavailable species for up take of Hg(II) and MeHg, respectively. (C) 1997 Elsevier Science Ltd.