Table IV. Digestion Method for Seawater Hg In
method A B
sample I 7.3 f 1.20 7.7 f 1.4
C
a
seawater, nglL sample II
8.3f 0.5 7.6 f 1.5
To 500 mL of seawater were added the following: (A) 5 mL of HzSO.4; allow to stand for >20 days; (5)5 mL of HzSO4 and 10 mL of " 0 3 : heat for 4 h; (C) 5 rnL of H2SO4, 5 mL of HN03, 4 rnL of 5 % KMn04, and 4 mL of 5 % K2S208; heat for 2 h. Standard deviation. E
seawater sample immediately after sampling, and stored for more than 20 days. (B) T o sample A, 10 mL of concentrated "03 was added and the solution was heated for 4 h in a boiling water hath. (C) T o sample A, 5 mL of concentrated HNO3 and 4 mL each of 5% K M n 0 4 solution and 5% K2S208 solution was added; the sample was heated for 2 h in boiling water. Among thle three digestion methods, no significant differences were found in the analyzed Hg values a t a 95% confidence level, and therefore each of the three methods seems to give total mercury. From the point of view of reagent contamination, the simplest method (A) is recommended for seawater.
Mercury Concentration in t h e Ocean Using the precautions stated above, the determination of Hg in seawater has been carried out by the authors. Part of the data was already reported without a description of the back-
ground of the analysis (12).By our determinations, a 5-6-ng/L level may be a reliable value for the base line of Hg in unpolluted oceans, which is roughly l / ~ oor '/loo lower than the concentrations reported in the literature, except for several recent reports of relatively low values (13-17).
Literature Cited (1) Nishimura, M., Matsunaga, K., Konishi, S., Runseki Kagaku, 24, 656 (1975). (2) Uchino, E.. Konishi, S., Nishimura, M., ibid., 27,457 (1978). (3) Jenne, E. A,. Avotins, P., J . Enuiron. Qual., 4,427 (1975). (4) Sanemasa, I., Deguchi, T., Urata, K., Tomooka, J . , Nagai, H., A d . Chim. Acta, 87,479 (1976). ( 5 ) Weiss, H. V., Shipman, W. H., Guttman, M. A , , ibid., 81, 211 (1976). (6) Carron, J., Agemian, H., ibid., 92,61 (1977). (7) Mahan, K. I., Mahan, S. E., Anal. Chem., 49,662 (1977). (8) Nishimura, M., Konishi, S., Kaiyo Kagaku (Mar. Sci., J p n . ) , 8, 820 (1976). (9) Ambe, M., Suwabe, K., Anal. Chim.Acta, 92,55 (1977). (10) Bothner, M. H., Robertson, D. E., Anal. Chem., 47, 592 (1975). (11) Carr, R. A,, Wilkniss, P. E.; Entliron. Sei. Techno/., 7, 62 (1973). (12) Matsunaga, K., Nishimura, M., Konishi, S., Nature (London), 258,224 (1975). (13) Burton, J. D., Leatherland, T. M., ibid., 231,440 (1971). (14) Leatherland, T. M., Burton, J. D., McCartney, M. J., Culkin, F., ibid., 232,112 (1971). (16) Fitzgerald, W. F., Hunt. C. D., J . Rech. Atmos., 8,629 (1974). ( 1 6 ) Fitzgerald, W. F., Adc. Chem. Ser., No. 147,99 (1975). (17) Fitzgerald, W. F., Lyons, W. B., Limnol. Oceanogr., 20, 468 (1976).
Receiced for reuieu: April 24, 1978. Accepted J u l y 27, 1978
Distribution of Polychlorinated Biphenyls (PCB) in Estuarine Ecosystems. Testing the Concept of Equilibrium Partitioning in the Marine Environment S. P. Pavlou" and R. N. Dexter URS Company, Fourth and Vine Building, Seattle, Washington 98121
w
Spatial and temporal trends in the chlorobiphenyl concentrations observed in various marine components of Puget Sound between 1973 and 1977 are presented. The distribution and accumulation characteristics are discussed in terms of the physical chemical processes that control their flow throughout the ecosystem. For the low levels detected in seawater, the data suggest that uptake is predominantly governed by equilibrium partitioning of the chemicals between suspended phases and ambient water. In 1972 we initiated a project to study the distribution and bioaccumulation characteristics of polychlorinated biphenyls (PCBs) in Puget Sound, Wash. These studies were intended to provide a data base for adopting appropriate criteria for regional enforcement, as well as an estimate of the potential hazard to the ecosystem ( I ) . Throughout the course of the study, it was realized that in order to assess the impact of these chemicals on the marine biota, it was necessary to obtain some quantitative information on the mechanism of accumulation based mainly on field residue data which reflect the concentrations commonly encountered in the marine environment. For the low levels detected in seawater, the data suggest that accumulation in 1 he various marine components, including biological uptake, is predominantly governed by equilibrium partitioning (1-3). 0013-936X/79/091:~-0065$01.OO/O @ 1979 American
Chemical Society
The material presented in this paper includes (a) a general discussion on the characteristics of the distribution and fluxes of PCBs in Puget Sound, (b) an evaluation of the partitioning mechanism in suspended phases and lower trophic level biota, and (c) a discussion of the implications of the equilibrium partitioning concept to the general distribution of persistent organic compounds in the marine environment.
Distribution of PCBs i n Puget Sound The field program completed during these studies has provided us with a sufficient data base to obtain a fairly coherent and comprehensive description of the distribution of PCBs in Puget Sound. The regions investigated have been presented in a previous report (2, Figure 1).A complete presentation of the PCB data, together with supporting hydrographic and biological measurements, is available elsewhere (3-6). These publications also contain a detailed discussion on sampling and analytical methodology. Characteristics of the Spatial Distribution. A summary of the mean PCB levels in Puget Sound is presented in Table I. The large standard deviation exhibited in certain subregions results from the existence of spatial variability within the region. Nevertheless, the data as presented in the table facilitate the delineation of regional trends. In general, the values for all sample types correlate well with areas of increased industrial and municipal activity. The water, susVolume 13, Number 1, January 1979 65
Table 1. Mean Total Polychlorinated Biphenyl Concentrations in Various Regions of Puget Sound
Duwamish River Elliott Bay Main Basin Sinclair Inlet Whidbey Basin Northern Sound and Straits of Juna d e Fuca Southern Sound Commencement Bay Hood Canal a
SPM,
water ng L-+
area
zooplankton,
ng g-’
4.4 f 2.2 (15) 3.7 f 1.7 (9)
3.0 f 2.2 (12)
sediment,
wg ( g of lipid)-‘
1770 f 540 (70) 920 f 200 (87) 104 f 31 (3) 168 f 21 (4) a2 f 37 (7)
22 f 13 (60) 5.4 f 1 3 (185) 4.3 (1)
88 f 37 (3)
6.8 f 3.1 (11) 5.9 f 4.4 (4) 16 f 7.0 (3) 3.7 f 1.1 (12) 1.3 f 1.2 (3)
a
ng g-l
surface film, ng ~ - 1
637 f 830 (4)
116 f 101 (5) 98 f 8 3 (6) 12 (1)
30 f 14 (5) 16 f 13 (3) 8.0 f 8.3 (6) 28 f 17 (8) 12 f 3.0 (3)
1.8 f 1.0 (4)
Values in parentheses are the number of data points.
Table II. Mean Polychlorinated Biphenyl Concentrations in the Surface and Deep Water Layers of Puget Sound a concn, ng L-1 Surface ( 25 m )
22 f 13 (60) 7.7 f 7.6 (64) 4.3
4.2 f 7.1 (121)
4.2 f 1.7 (10) 3.6 f 1.5 (6)
5.0 f 3.2 (5) 4.1 f 2.4 (3)
2.6 f 2.3 (8)
3.7 f 2.2 (4)
sediments, region
freshwater Lake Ontario Lake Michigan Hudson River Connecticut River Ouwamish River marine Atlantic Ocean Gulf of Mexico Escambia Bay California California Current S. California Bight Palos Verdes Peninsula San Francisco Bay Puget Sound
water, ng ~ - 1
55
