RADIOISOTOPIC STUDY OF MERCURY UPTAKE 277 



in Standard Methods (American Public Health Association, 1971). 

 Algal cell counts and carbon values were obtained from ongoing 

 ecological studies of the Hudson River at Indian Point (New York 

 University Medical Center, 1976; P. Storm, New York University, 

 unpublished data). Turbidity, phosphate, and nitrogen levels were 

 obtained from Lawler, Matusky, and Skelly Engineers (1976). 



Statistical Analysis 



All experimental data were converted to natural logarithms 

 before analysis. Bartlett's test for homogeneity of variance and the 

 Kolmogorov— Smirnov test for normality were run to ensure that 

 assumptions of the analysis of variance (ANOVA) were met. Once 

 differences were shown, the Scheffe test compared each experiment 

 for significant differences. Multiple regression analysis (Nie et al., 

 1975) was used as an inferential tool for evaluating the relationship 

 between mercury uptake and fluctuations in the chemical and 

 physical parameters of Hudson River water. 



RESULTS 



Both fish larvae and zooplankton took up mercury directly from 

 water and from food. In most cases mercury uptake from filtered 

 river water was similar in degree to uptake from whole river water 

 and from labeled algae, detritus, and bacteria. Presence of sediment 

 reduced the level of mercury in organisms (Table 1). 



Comparing the concentration factors for several Hudson River 

 species shows that each species is able to concentrate all four forms 

 of mercury to a considerable extent over the water phase. After a 

 1-day exposure, mercury concentration in organisms was 10^ to 10^ 

 times that in the filtered river water (Tables 2 and 3). In general, 

 Hudson River algae and microzooplankton showed much higher 

 concentration factors (50,000 to 1,000,000) than macrozooplankton 

 (1,000 to 30,000) and fish (1,000 to 10,000). Of the Crustacea, the 

 filter feeders (e.g., Eurytemora affinis, Acartia tonsa, and Daphnia 

 pulex) show greater concentrations of mercury taken up from river 

 water than carnivorous copepods (e.g., cyclopoid copepods) or 

 detrital feeders (e.g., Gammarus sp.). 



Gammarus sp. was extensively studied to determine if there was 

 greater uptake of organic mercury than of inorganic mercury. 

 One-way ANOVA comparing uptake of four mercury compounds 

 [Hg(N03 )2 , HgCU , HgCHj CI, 0HgCOOCH3 ] showed no differences 

 after 1 day (68 df, P > 0.05), but there were differences at 1 week 



