Levels of environmental pollutants in flounder (Platichthys flesus L.) and cod (Gadus morhua L.) caught in the waterway of Glomma, Norway. II. Mercury and arsenic.

The present study is a survey on mercury and arsenic pollution in two sedentary fish species stationed in or close to the Glomma estuary in the Hvaler archipelago, Norway. Mercury and arsenic were determined individually in 80 flounder (Platichthys flesus L.) and 100 cod (Gadus morhua L.). The fish were caught at five different localities near or in the relatively polluted Glomma estuary. There were significantly higher mercury and arsenic concentrations in fillets of flounder than in fillets of cod (wet weight), 0.15 vs. 0.08 mg/kg and 5.2 vs. 4.1 mg/kg, respectively. Seasonal variation in mercury concentration was only found in flounder, with a significantly higher level in spring than in autumn. A significant increase in mercury content with increasing age was found for both species. For cod, a significantly higher arsenic level was found on the outer stations as compared to the inner stations, while arsenic levels in flounder was less dependent on sampling site.

Levels of environmental pollutants in male and female flounder (Platichthys flesus L.) and cod (Gadus morhua L.) caught during the year 1988 near or in the waterway of Glomma, the largest river of Norway. I. Polychlorinated biphenyls.

Levels of polychlorinated biphenyls, PCBs, in liver samples of 111 and 121 flounder (Platichthys flesus L.) and cod (Gadus morhua L.), respectively, were determined gas chromatographically by quantification of 9 individual PCB congeners. The congeners were 28, 52, 101, 118, 153, 138, 180, 170, and 209 (IUPAC numbering system, Ballschmiter and Zell 1980). The fish were caught during 1988 at 5 different stations near or in the Glomma estuary, in the Hvaler archipelago, Norway. The mean level of the sum of the congeners, 1,050 ng/g, found in cod was 3 times higher than the corresponding level found in flounder (361 ng/g). The influences on the variation in PCB levels of sex, season, and distance from the Glomma outlet and waterway were investigated using 1-, 2-, and 3-way ANOVA. The main effects of these factors as well as their possible interactions were considered. An expected decreasing PCB pollution gradient from the mouth of Glomma was found for cod, while PCB levels in flounder seemed to be less dependent on sampling site. However, the sexes in both fish species exhibited a different pattern in their PCB levels. The PCB levels in female cod were significantly affected by the season of sampling, with PCB levels in September/October significantly greater than the corresponding levels in June and November/December. No such effect was found for male cod. In flounder, a significant station effect on the PCB levels was found for females only, and a decreasing PCB pollution gradient was found to be significant. The interactions between the three factors station, season, and sex were different in the two species.(ABSTRACT TRUNCATED AT 250 WORDS)