Influence of water quality on the accumulation of methyl 203mercury in gill tissue of minnow (Phoxinus phoxinus).

Effects of pH and concentrations of Cl and Ca on the uptake of methyl mercury (MeHg) in the gills of the minnow (Phoxinus phoxinus) were studied. Chloride concentration and pH in the water affect the speciation of MeHg. Ca was included because it affects the permeability of the gills and could therefore indirectly affect the amount of MeHg accumulated in the tissue. The species formed differ in hydrophobicity, as reflected in their octanol/water partition coefficients (Pow). Both a reduction in pH and an increase in Cl- concentration increased the Pow of MeHg. Ca had no effect on speciation. The accumulation of MeHg in the gill tissue increased with decreasing pH (from pH 7.0 to pH 3.9). Accumulation also increased as Cl- concentrations were increased from 10(-7) to 10(-1) M at pH 7.0. An increase in Ca concentration did not alter the accumulation of MeHg beyond a decrease in MeHg accumulation as Ca increased from 20 to 50 microM. We conclude that, of the water-quality factors studied, those affecting chemical speciation were most important in determining the MeHg uptake. The Ca concentration appears to be of minor importance.