No abstract

A fast semimicro method for the determination of methyl mercury in fish tissue is described. The procedure involves extracting the methyl mercury into toluene as methyl mercuric bromide, partitioning the bromide into aqueous ethanol as a thiosulfate complex, and re-extracting into benzene as methyl mercuric iodide. Methyl mercury is quantitated with gas chromatography. The method is sensitive to 0.01 ppm. Recoveries of added methyl mercury were 99% and the presence of methyl mercury in the final extract was shown by thin layer chromatography and gas chromatography of the thin layer spot. A variety of mercurial compounds do not interfere in the analyses. The amounts of both methyl and total mercury found in a variety of tissues of aquatic animals are compared. The presence of a demethylase in seal is suggested by the findings of high levels of nonmethyl mercury. Additional cleanup by column chromatography on Florisil was necessary with certain samples. The gas chromatographic columns were kept operational by the intermittent injection of 3M potassium iodide. Due to column bleed and resulting detector contamination, the use of the easily cleaned concentric tube electron capture detector is recommended.

A simple, rapid method is given for determination in fish of mercury at concentrations measured in parts per million (ppm). Samples are digested at 50–60 C with sulphuric acid and oxidised with permanganate. Mercury in the digest is determined by atomic absorption spectrophotometry. Recovery of mercury added to samples was complete, with good precision. Standard deviations from triplicate analyses were ±0.039 at the 0.1 ppm level and ±0.051 at the 0.5 ppm level. In a day, three workers analysed 15–20 samples in triplicate.

Northern pike heavily contaminated with methylmercury were captured from Clay Lake, Ontario, and released in Heming Lake, Manitoba, an area relatively free of mercury. Mercury levels in muscle biopsy samples at the time of transfer and at subsequent recaptures indicated that only 30% was eliminated in one year. Distribution among various body tissues was essentially unchanged, those organs most heavily contaminated being lens, kidney, and liver in decreasing order. Biochemical profiles of blood serum constituents showed several differences between samples from the two lakes, especially in levels of inorganic phosphate, total protein, alkaline phosphatase, and cortisol. Serum values for transplanted fish tended toward those in the clean lake and we have concluded that biochemical profiles were sensitive to the environmental change.

Uthe, 1. F., and C, L. Chsu. 1987. Cadmium in sea scallop (Placapecten rnagellanicus) tissues from clean and contaminated areas. Can. 1. Fish. Aquat. Sci. 44: I81 -98.Over 90% of the total cadmium in the soft tissues of sea scallops (Placapecten rnagellanicus) was in the digestive gland with less than 1 % in the adductor muscle. The amount of cadmium in the digestive gland was significantly related to shell height. Shell height was superior to age as an independent (predictor) variable due to difficulties in ageing scallops. Based on these relationships, scallops of approximately 100 mm shell height were selected to study interregional differences. Neither cadmium concentration nor burden could be used to identify contaminated areas. The ratio of digestive gland cadmium to that in the adductor muscle was lowest for scallops from Chaleur Bay, which had received substantial anthropogenic cadmium input, and for scallops that had k e n starved for approximately 14 mo. We suggest that the high tissue cadmium levels iw scallops from Gesrges Bank and Browns Bank are not due to contamination from antkropogenic or natural sources but rather reflect feeding and the nutritional inadequacy of the diets. Conversely, the high levels of cadmium input to Chaleur Bay were not reflected in high tissue concentrations or burdens in scallops.Plus de 90 % du cadmium des tissues mous des petoncles geants (Placcspeeten rnagellanieus) se trouvait dans la glande digestive avec moins de 1 % dans le muscle adducteur. La quantitk de cadmium dans la glande digestive etait iiee de maniere significative I'epaisseur du coquillage. L'epaisseur du c?quillage etait une meilleure variable indkpendante que I'age qui est difficile i % dkterminer cken re pktoncle. A partir de ces relations, on a chsisi des coquillages de 188 mm d'epaisseur pour 6tudier les differences inter-regionales. Ni la concentration ni la charge en cadmium n'a pu wrvir 3 indentifier les zones contaminees. Le rapport de la concentration de cadmium de la glande digestive a celle du muscle adducteur etait plus faible que celui des petoncles de la baie des Chaleurs qui avaient absorb6 une quantite substantielle de cadmium anthropogene et que celui des pbtsncles qui avaient kt6 privks de nsurriture pendant envirsn 14 mo. Les fortes teneurs en cadmium des pt5toncles du banc de Gecbrges, et en particulier du banc de Browns, ne tiendraient pas A une contamination d'origine anthropoghe ou naturelle, mais plutdt aux habitudes alimentaires et 2 I'equilibre de leur alimentation. Bar ailleurs, les deckarges elevkes de cadmium a la Baie des Chaleurs ne semblent pas 6tre associkes ni aux concentrations ni aux charges observkes dans les tissues des petoncles.(J8777) ver the past decade or so the use of bivalves such as mussels as sentinel indicators sf coastal contamination by trace metals and other anthropgenic chemicals has gmwn in popularity (U.S. National Academy of Sciences 1988; Phillips 1980). Concern over the presence of trace metals in marine bida from a human health point of view has a...