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Toxicities of ten metals to Crassostrea gigas and Mytilus edulis embryos and Cancer magister larvae
Volume 12/Number 9/September 1981 g r o u n d e d in the S t o c k h o l m archipelago (Sweden), a n d a b o u t 1000 t oil were spilled in the n o r t h e r n B a l t i c . . . I am deeply grateful to Dr Erkki Lepp~tkoski, acting project leader for the biological monitoring group, and to Ea Blomqvist, Pentti Kangas, Annikki Lappalainen, Hans-Olof Lith~n, Kari Ranta-aho, Sinikka Suomalainen and Kjell Weppling for assistance in the fieldwork and in sorting of the samples. Mr TorbjOm Dale gave valuable comments on the manuscript. The investigation was financed by the Finnish Ministry of the Interior, Department for Environmental Protection. Ankar, S. (1977). The soft bottom ecosystem of the northern Baltic proper with special reference to the macrofauna. Contr. AskO Lab., 19, 1-62. Ankar, S. & Elmgren, R. (1976). The benthic macro- and meiofauna of the Ask0-Landsort area (northern Baltic proper). A stratified random sampling survey. Contr. AskO Lab., 11, 1-115. Dybern, B. 1., Ackefors, H. & Elmgren, R. (1976). Recommendations on methods for marine biological studies in the Baltic Sea. BMB Publ. No. 1, 1-98. Elmgren, R., Hansson, S., Larsson, U. & Sundelin, B. (1980). Impact of oil on deep soft bottoms. In The Tsesis oil spill (J. J. Kineman, R. Elmgren and S. Hansson, eds.). Report of the first year scientific study (October 1977 to December 1978). A cooperative international investigation by AskO Lab. University of Stockholm, Sweden, IVL, Sweden and NOAA, USA. Fagerholm, H. P. (1975). The effects of ferry traffic on the rocky shore macrofauna in the southern ~.land archipelago. 1. The Cladophora zone. Merentutkimuslait. Julk./Havsforskingsinst. Skr., 239, 331-337.
Marine Pollution Bulletin, VoL 12, No. 9, pp. 305-308, 1981 Printed in Great Britain
Finnish IBP-PM group (1969). Quantitative sampling equipment for the littoral benthos (1). Int. Rev. ges. Hydrobiol. Hydrogr., 54, 185-193. Johnsson, S., Larsson, U. & Boehm, P. (1980). The gkesis oil spill. Impact on the pelagic ecosystem. Mar. Pollut. Bull., 11, 284-293. Kikuchi, T. & Tanaka, M. (1978). Ecological studies on the benthic macrofauna in Tomoe Cove, Amakusa. I. Community structure and seasonal change of biomass. Publ. Amakusa Mar. Biol. Lab., 4, 189-213. Leppakoski, E. (1973). Effects of an oil spill in the northern Baltic. Mar. Pollut. Bull., 4, 93-94. Lepp~tkoski, E. (1975). Assessment of degree of pollution on the basis of macrozoobenthos in marine and brackish-water environments. Acta Acad. Aboensis, Ser. B., 351, 1-90. Lepp~koski, E. & LindstrOm, L. (1978). Recovery of benthic macrofauna from chronic pollution in the sea area off a refinery plant, southwest Finland. J. Fish. Res. Bd. Can., 35, 766-775. Lind6n, O., Elmgren, R. & Boehm, P. (1979). The T~esis oil spill. Ambio, 8,244-253. Notini, M. (1978). Long-term effects of an oil spill on Fucus macrofauna in a small Baltic bay. J. Fish. Res. Bd. Can., 35,745-753. Pf'Lster, K. (1980). The 1979Baltic Oil Spill. Department for Environmental Protection, Ministry of the Interior. Helsinki. Segerstr/ile, S. G. (1973). Results of bottom fauna sampling in certain localities in the Tvarminne area (inner Baltic), with special reference to the so called Macoma-Pontoporeia theory. Comm. Biol. Soc. Sci. Fenn. 67, 3-12. Segerstr[tle, S. G. (1978). The negative correlation between abundances of the amphipod Pontoporeia and the bivalve Macoma in Baltic waters, and the factors involved. Ann. Zool. Fennici, 15, 143-145. Westerberg, J. (1978). Macrobenthic diversity and organic pollution in the archipelago of ~land (N. Baltic). Aqua Fennica, 1978, 70-77.
0025 -326X/81/090305 4)4 $02.00/0 © 1981 Pergamon Press Ltd.
Toxicities of Ten Metals to Crassostrea g/gas and Mytilus edulis Embryos and Cancer magister Larvae M I C H A E L M A R T I N , * K E N N E T H E. O S B O R N , 1- P A T R I C I A B I L L I G , a n d N E l L G L I C K S T E I N § *California D e p a r t m e n t o f f i s h a n d Game, Marine Pollution Studies Laboratory, 2201 Garden Road, Monterey, C A 93940, U S A +East B a y Municipal Utility District, P.O. B o x 24055, Oakland, C A 94623, USA ~:P.O. B o x 6 8 , Kelly, W Y 8 3 0 1 1 , USA §P. O. B o x 3 3 1 , Rockport, M A 01966, USA
Pacific oyster (Crassostrea g/gas T h u n b e r g ) e m b r y o s , b a y mussel (Mytilus edulis L i n n a e u s ) e m b r y o s , a n d D u n g e n e s s crab (Cancer magister D a n a ) zoea I stage larvae were exposed to arsenic, c a d m i u m , chromium, copper, lead, mercury, nickel, s e l e n i u m , silver, and zinc salts. T h e two bivalve species were exposed t h r o u g h the c o m p l e t i o n of embryogenesis (48 h), a n d the effects of the metals upon a b n o r m a l d e v e l o p m e n t were m o n i t o r e d . T h e crab larval stages were exposed to the metal s o l u t i o n s for 96 h. C o n c e n t r a t i o n s ( / a g I_ 1 as metal) which caused 50070 a b n o r m a l development in the two species of bivalve larvae and which were fatal to 50070 of the crab larvae r a n g e d from 5.3 (oyster) to 49 (crab) for copper; 5.8 (mussel) to 8.2 (crab) for m e r c u r y ; 14 (mussel) to 55 (crab) for silver; 119 (oyster) to 456 (crab) for zinc; 232 (crab) to 3000 (mussel) for
arsenic; 247 (crab) to 1200 (mussel) for c a d m i u m ; 349 (oyster) to 4360 (crab) for nickel; 476 (mussel) to 758 (oyster) for lead; 3440 (crab) to 4538 (oyster) for hexavalent
chromium; and selenium greater than 10 000 for the three species. T h e acute toxicity testing of C. g/gas e m b r y o together with two C a l i f o r n i a native species c o n f i r m e d its
usefulness for predicting toxicity to the latter species.
T h e toxicities o f trace metals to larval stages o f i m p o r t a n t m a r i n e species have b e e n reported b y a large n u m b e r o f investigators. T h e increased c o n c e r n regarding the use o f oceans as a site for the disposal o f a n t h r o p o g e n i c wastes (Eisler & H e n n e k e y , 1977), as well as the potential for increased v o l u m e s o f a n t h r o p o g e n i c wastes to C a l i f o r n i a 305
Marine Pollution Bulletin
marine waters, prompted a multispecies evaluation of selected metal toxicities to representative California species through short-term static bioassays. Eisler et al. (1978) reviewed the literature of the effects of metals and found less than one-third of the toxicity papers related to larval and embryo studies. In general, larvae or embryos prove to be less tolerant to toxic materials than adults of the same species, and hence would appear to be the critical life stages for toxicity testing (Vernberg et al., 1974; Calabrese et al., 1973). This study was undertaken: (a) to quantify the toxicities of ten metals on marine invertebrate embryos and larvae and (b) to compare the responses of two species of bivalves and one species of crustacean: Crassostrea gigas (Pacific giant oyster), Mytilus edulis (bay mussel) and Cancer magister (Dungeness crab). These invertebrate species were selected as test organisms because of their wide distribution in California, importance to its commercial fisheries, and ability of the species to be cultured in the laboratory. The metal species were selected because of their common occurrence in municipal and industrial waste effluents as well as their well known toxicity to marine organisms in general.
Materials and Methods Experiments were conducted at the California Department of Fish and Game, Marine Pollution Studies Laboratory, Big Sur, Monterey County, California, USA. Natural seawater was filtered through double 1 lam polypropylene media filters and U.V. sterilized (hereafter referred t o as' treated water'). Stock solutions of trace metals were prepared at 1000 mg 1_~ in quartz distilled water using analytical grade soluble salts: A g N O 3 , AS203, CdC12, C u S O 4 , K z C r O 7 , H g C I 2 , NiSO4 • 6H20, Pb(NO3)2, SeO2 and ZnSO4. Addition of 1 ml double-distilled HNO3 to 1 I. of metal stock solution reduced surface plating on container walls as well as increased metal solubility. Actual concentrations of stock solutions were verified against known standards and doubledistilled water blanks using a Perkin-Elmer 305 atomic absorption spectrophotometer with air-acetylene flame for Hg and Se and graphite furnace with a deuterium arc background corrector for Ag, Cd, Cu, Cr, Ni, Pb and Zn. Test solutions were prepared by appropriate volumetric dilution of stock solution with treated seawater. Results of metal concentrations are expressed as/ag 1_ ~ in excess of background. Accurate techniques to measure directly seawater background concentrations for Ag, As, Cr, Hg, Ni and Se were judged to be not available. Cd, Cu, Pb and Zn concentrations ~ g 1_ 1) for the laboratory treated water were, respectively (n=3): 0.03 +- 0.009, 0.057 +- 0.030, 0.263 +- 0.082, 0.023 +- 0.005. It could be assumed that concentrations of the non-measured chemical species were below threshold response levels of organisms, as indicated by control mortalities of < 5 °70. The laboratory seawater intake is located at least 4 km from a known or suspected point source for metals. This site is 0.5 km from a California State Mussel Watch station at Soberanes Point (Stephenson et al., 1979) and has shown low metal values. 306
Seawater water quality parameters were monitored during the experiments: pH = 8.1 +_ 0.2 (Corning Model 10); dissolved oxygen ranged from 6.5 to 8.0 mg 1_ 1 (YSI Model 57 Oxygen Meter); and salinity=33.79 +- 0.07070 (Industrial Instruments, Inc., Induction Salinometer Model No. RS-7B). Crassostrea gigas Experiments Adult Pacific giant oysters, Crassostrea gigas, obtained from Johnsons Oyster Company, Inverness, California, were thermally conditioned in the laboratory for 3-5 weeks at 20°+- I°C. Preconditioned oysters were thermally stimulated (28°-30°C) in treated seawater, and augmented with a sperm suspension (Woelke, 1972). Six to seven thousand fertilized eggs were incubated in 5% HNO 3 acidsoaked 250 ml beakers (polypropylene Tripour) for 48 h at 20 ° +- I°C. For each experiment, three replicates for each metal concentration were used. After incubation, larvae were concentrated using a 35-/am nitex screen and preserved in 10070 buffered formalin. Approximately 100 larvae were counted per test concentration under 100 x magnification. Larvae which failed to transform to the shelled, hinged 'D' shaped veliger constituted the 'abnormal' criterion. Mytilus edulis Experiments Adult bay mussels, Mytilus edulis, were obtained from American Shellfish Corporation, Moss Landing. The adult animals were received and maintained in spawning condition for up to 5 weeks in unfiltered, untreated seawater at 14 ° + 1°C. Prior to spawning, the mussels were placed in freshwater for 15 min., followed by desiccation for 2 h. The valves of the adults were then wedged open with wooden splints, applying stress to the posterior adductor muscle (after Loosanoff & Davis, 1963). The embryos were incubated at 17 °+_ 1°C for 48 h. Concentration, preservation, and abnormal criteria for the larvae were as described for C. gigas. Cancer magister Experiments First-stage zoeae of the market crab, C. magister, were provided by the California Department of Fish and Game, Marine Culture Laboratory, Big Sur, Monterey County. Zoeae I stage animals were collected within 12 h of release from the egg sponge of the adult female crab and held for 48 TABLE 1
Crassostrea gigas, Mytilus edulis, and Cancer magister. Abnormal development represented as 48 h ECs0s for oyster and mussel embryos and toxicity represented as 96 h LC50s for crab zoeae. Values are expressed as /ag 1_ 1 metal _+ 1 standard deviation. N is the number of experiments performed (with 3 replicates). Species
Toxicant
N
CuSO 4
2 3 2 3 4 3 2 3 3 3
HgCl 2 AgNO3 ZnSO4 AsO 5 NiSO 4 . 6H20 CdCI 2 Pb(NO3) 2 KzCrO 7 SeO 2
C. gigas
M. edulis
C. magister
embryos
embryos
zoeae
ECso (/agl_ I) 5.3 -+ 0.47 6.7 ± 1.55 22_+ 13.3 119_+ 12.0 326 _+ 69.9 349± 49.5 611 _+ 195.9 758 +_ 20.4 4538± 724 > 10 000
N
ECso (wgl_ L) N
2 2 2 I 1 2 1 2 2
5.8± 1 5.8_+ 1 14± 2 175 > 3000 8 9 1 - +209 1200 476-+ 1 4469± 739
3 5 4 4 1 2 1 3 1
1
> 10000
4
EC5o ~gl.-I) 49___ 19.6 8.2_+3.66 55± 20.8 456_+ 174 232 4360_+ 2205 247 575± 192 3440 > 10000
Volume 12/Number9/September 1981 LCs0 for Hg ranging from 1.0 to 3.3 tag 1_ 1. Calabrese et al. (1973) reported 48 h LCs0 for Crassostrea virginica embryos as follows: Hg (5.6 tag 1_1); Ag (5.8 tag l_l); Cu (103 tag 1_1); Zn (310 tag 1: ~); Ni (1180 tag 1_ ~); Pb (2450 tag 1_ ~); Cd (3800 tag 1_ ~)and As (7500 tag 1_ ~). Later studies by Calabrese et al. (1977) show 12-day LCso responses for C. virginica which are similar to the48 h LCs0 ofC. gigas: Hg (12 tag 1_~), Ag(25 tag 1_ ~), and Cu (33 tag 1_ ~). MacInnes & Calabrese (1978) report 48 h LC~0 values for C. virginica embryos of Hg (10.2 tag 1_ ~), Cu (15.1 tag 1_ ~), Ag (24.2 tag 1_ ~)and Zn (205 tag 1_ ~). The latter reported values for C. virginica are similar to the Statistics C. gigas responses reported herein. Woelke (1972) found the The bioassay results were analysed using the methods concentration of chemicals which did not affect embryonic described by Woelke (1972), using probit analysis (Finney, development of C. gigas at 27°C: Cu (32 tag 1_~), Hg (10 tag 1971) for estimates of ECs0s or LCs0s. 1_J), Zn (1000 tag 1_ ~), and Cr 6+ (3200 tag 1_ J). Although the criterion for 'not affected' was not described, it is evident Results that, except for Hg and Cr, the C. gigas from Woelke's experiments were approximately a factor of 10 more The acute toxicities of the trace metals to C. gigas, M. tolerant than the results of our studies. Several physical or edulis and C. magister (Table 1) are represented by mean chemical factors can affect the toxicity of specific chemicals, concentrations (48 h ECs0 or 96 h LCs0) necessary to inhibit such as temperature differences, decreased metal concendevelopment or cause mortality. The criterion of trations from adsorption to container surfaces, complexing 'abnormal' shell development in bivalve larvae represents a with organic constituents in sea water, and gaseous sublethal response that leads to certain nonrecruitment into exchange or loss (Glickstein, 1979). the population due to increased predatory pressure from Mytilus edulis embryos show toxic responses to metals longer pelagic existence. Furthermore, morphological similar to Crassostrea gigas except for Pb, Ni, Cd and As. deformities in the larvae of broadcast fertilizers can only With the exception of Pb, C. gigas is more sensitive by a result in severely decreased chances of survival for the general factor of 2. Woelke (1972) reported a similarity offspring. Finally, acute sublethal responses to mercury on in Mytilus edulis and C. gigas embryo toxic responses for larval Uca pugilator have been positively correlated with Cu, Hg and Cr, while M. edulis had one-third the tolerance chronic lethality (De Coursey & Vernberg, 1972). Selenium of C. gigas for zinc. Hrs-Brenko et al. (1977) found Mytilus did not produce a dose response in bivalve embryos or crab galloprovincialis embryos had optimal development at a larvae at concentrations less than 10 000 tag 1_ 1. salinity of 34.8 %00and temperature of 15.6 °C. The effect of The responses ofC. gigasembryos to the 10 metals ranged over four orders of magnitude. The most toxic metals, lead was minimal in optimal salinity and temperature conditions at concentrations up to 1000 tag 1_ ~, although at expressed as 48 h ECs0, were copper (5.3 tag !_ ~), mercury (6.7 tag |_ ~), and silver (22 tag l_ ~). C. gigas embryos were the higher concentrations it caused a delay or inhibition of least affected by hexavalent chromium (ECs0 = 4538 tag l_ ~) embryonic development. Cancer magister zoeae are more sensitive to copper, and selenium (> 10 000tag 1_ ~). cadmium and zinc than are crab larvae of an Australian M. edulis embryos show a similar pattern of response to species (Paragrapsus quadridentatus), by a factor of trace metal toxicity as with C. gigas. Mercury, copper and silver are the most toxic with 48 h ECs0 values of 5.8 tag 1_ 1 approximately three (Ahsanullah & Arnott, 1978). The 48 h LCs0 for Carcinas maenas larvae was 10 tag 1_ ~(Hg) and 330 for the first two metals and 14 tag 1_ ~ for silver. Under experimental conditions, the bay mussels embryos show the tag 1_ j (Cu)(Conner, 1972). Rosenberg & Costlow (1976) reported a decreased survival and significant delay in following rank order of toxicity: Hg and Cu > Ag > Zn > development from megalopa to third stage of blue crabs P b > N i > C d > A s > C r > Se. (Callinetes sapidus) in 50 tag 1_~ Cd over four salinity The 96 h LC~o values of Cancer magister correspond to the pattern shown by those of Crassostrea gigas, with certain regimes. Mirkes etal. (1978) report that 10 tag 1_ t Cd for 24 h exceptions. In the bivalve larvae, copper and mercury elicit exposure caused a 20% mortality (= LC20) for the mud crab, almost identical responses at very low concentrations Eurypanopeus depressus, in zoeae I larvae. Woelke (1972) proposed the use of C. gigas embryo while Cancer magister is more sensitive to mercury (LC50=8.2 tag 1- ~) than copper (LC50=49 tag 1_~). Silver, bioassays as a water quality criterion for the protection of with an LCs0 of 55 tag 1_ ~, has almost the same toxicity as marine resources. One often stated criticism of the use of copper in C. rnagister. Cancer magister zoeae are more laboratory obtained toxicity data is that it fails to consider sensitive to cadmium and arsenic than Crassostrea gigas. adequately 'natural detoxifying' mechanisms, such as Cancer magister is an order of magnitude more tolerant of particulate concentration or organic content, of the nickel (4360 tag l_q than both species of bivalve larvae receiving water. It is our opinion that regulatory authorities should adopt water quality criteria that reflect 'worse case' tested. conditions, and individual field situations should be considered, on a case-by-case basis, backed by factual Discussion information. The difficulty in a laboratory experiment to The responses of the three invertebrate marine species duplicate the multi-factoral variables found in field tested compared favourably with other toxicity testing situations is obvious. results. Conner (1972) found Ostrea edulis larvae had a 48 h The testing procedures of these studies allows a
h (15 _+ 1°C) to allow acclimation. Handling of zoeae was by large bore capillary tubing (4 mm) to minimize handling stress. Five zoeae were placed in 251Yml glass beakers and fed 200 freshly hatched brine shrimp nauplii per ml of culture solution, initially, and at 48 h of exposure. Twenty zoeae were tested per experimental concentration. Mortalities were recorded at 24, 48, 72 and 96 h of exposure to toxic solutions. An opaque, non-motile individual was the lethal response criterion.
307
Marine Pollution Bulletin comparison of two native California invertebrate marine species, of commercial, economic and ecological importance. Not surprisingly, the embryos of the bivalve
M y t i l u s edulis s h o w s a s i m i l a r r e s p o n s e t o all m e t a l s e x c e p t f o r a r s e n i c (9.2 x m o r e t o l e r a n t ) , silver a n d l e a d ( a l m o s t 2 x m o r e sensitive). T h e D u n g e n e s s c r a b s h o w s w i d e r v a r i a t i o n in r e s p o n s e s t o m e t a l s ; it is m o r e t h a n t w i c e as s e n s i t i v e t o c a d m i u m as t h e o y s t e r , as well as slightly m o r e sensitive t o a r s e n i c , lead a n d c h r o m i u m . T h e c r a b is s i g n i f i c a n t l y m o r e t o l e r a n t o f zinc (3.83 x ) , c o p p e r ( 9 . 2 5 x ) a n d n i c k e l (12.49 × ) t h a n t h e oyster. W i t h t h e r e c o g n i t i o n t h a t c e r t a i n species d i f f e r in r e s p o n s e t o m e t a l s , t h e P a c i f i c o y s t e r e m b r y o b i o a s s a y a p p e a r s t o h a v e m e r i t as a n ' i n d i c a t o r ' o r ' s t a n d a r d ' m a r i n e b i o a s s a y species in C a l i f o r n i a .
Ahsanullah, M. & Arnott, G.H. (1978). Acute toxicity of copper, cadmium, and zinc to larvae of the crab Paragrapsus quadridentatus (H. Milne Edwards), and implications for water quality criteria. A ust. J. mar. Freshwat. Res., 29, 1-8. Calabrese, A., Collier, R. S., Nelson, D. A. & Maclnnes, J. R. (1973). "Ihe toxicity of heavy metals to embryos of the American oyster Crassostrea virginica. Mar. Biol., 18,162-166. Calabrese, A., MacInnes, J. R., Nelson, D. A. & Miller, J. E. (1977). Survival and growth of bivalve larvae under heavy metal stress. Mar. Biol., 41,179-184. Conner, P. M. (1972). Acute toxicity of heavy metals to some marine larvae. Mar. Pollut. Bull., 3, 190-192. DeCoursey, P. J. & Vernberg, W. B. (1972). Effect of mercury on survival, metabolism and behaviour of larval Uca pugilator (Brachyura). Oikos, 23, 241-247.
Eisler, R. & Hennekey, R. J. (1977). Acute toxicities of C d 2+, C r 6+, Hg z +, Ni 2 + and Zn 2 + to estuarine macrofauna. ArchsEnvir. Contain. Toxic., 6, 315-323. Eisler, R., O'Neill, D. J., Jr. & Thompson, G. W. (1978). Third annotated bibliography on biological effects of metals in aquatic environments. (No. 1293-2246). U.S. Environmental Protection Agency Report 600/3-78-005. Finney, D. J. (1971). Prob# Analysis. Cambridge University Press, London. Glickstein, N. (1979). The potential loss of dissolved mercury and selenium in marine experimentation. Mar. Pollut. Bull., 10, 157. Hrs-Brenko, M., Claus, C. & Bubic, S. (1977). Synergistic effects of lead, salinity, and temperature on embryonic development of the mussel Mytilus galloprovincialis. Mar. BioL, 44, 109-115. Loosanoff, V. L. & Davis, H. C. (1963). Rearing of bivalve mollusks. In Advances in Marine Biology (F. S. Russel, ed.). Academic Press, London. Maclnnes, J. R. & Calabrese, A. (1978). Response of the embryos of the American oyster, Crassostrea virginica, to heavy metals at different temperatures. I n Physiology and Behavior of Marine Organisms (D. S. McLusky and A. J. Berry, eds.). Pergamon Press, New York. Mirkes, D. Z., Vernberg, W. B. & DeCoursey, P. J. (1978). Effects of cadmium and mercury on the behavioral responses and development of Eurypanopeusdepressus larvae. Mar. BioL, 47, 143-147. Rosenberg, R. & Costlow, J. D. Jr. (1976). Synergistic effects of cadmium and salinity combined with constant and cycling temperatures on the larval development of two estuarine crab species. Mar. Biol., 38, 291-303. Stephenson, M. D., Martin, M., Lange, S. E., Flegal, A. R. & Martin, J. H. (1979). California Mussel Watch 1977-1978. Volume II. Trace metal concentrations in the California mussel, Mytilus californianus. State Water Resources Control Board, Sacramento. Water Quality Monitoring Report No. 79-22. Vernberg, W. B., DeCoursey, P. J. & O'Harra, J. O. (1974). Multiple environmental factor effects on physiology and behavior of the fiddler crab, Uca pugilator. I n Poilu tion and Physiology of Marine Organisms (F. J. Vernberg and W. B. Vernberg, eds.). Academic Press, New York. Woelke, C. E. (1972). Development of a receiving water quality bioassay criterion based on the 48-hour Pacific oyster, Crassostrea gigas, embryo. Wash. Dept. Fish. Tech. Rept., 9, 1-93.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 308-314, 1981 Printed in Great Britain
0025-326X/81/090308-07 $02.00/0 © 198I Pergamon Press Ltd.
Plutonium Occurrence and Phase Distribution in Sediments of the Wyre Estuary, Northwest England S. R. A S T O N , * D. J. A S S I N D E R , D. A . S T A N N E R S * a n d J. E. R A E + D e p a r t m e n t o f E n v i r o n m e n t a l Sciences, University o f Lancaster, L a n c a s t e r L A 1 4 YQ, U K *Present address: International Laboratory of Marine Radioactivity, Mus~e OeOanographique, Monaco * Present address: Radiochernistry Division, J.R.C., Ispra 21020, Varese, Italy * Present address: Department of Geology, University of Reading, Reading, UK
The occurrence of plutonium isotopes derived from the Windscale reprocessing facility discharges and weapons test fallout in intertidal sediments of the Wyre estuary, northwest England, is reported. Windscale plutonium appears to be slowly transported to the estuary in association with sedimentary material, and its distribution in surface and buried sediments is controlled by the variations in organic matter content of the sediments and/or their 308
grain size characteristics. Results from chemical leaching experiments suggest that very little plutonium is ion exchangeable or in humic substances, but it is in other organic and Fe/Mn hydrous oxide fractions of the sediments. Plutonium shows a similar depositional behaviour to mercury which enters the Wyre directly in local industrial discharges.
Marine Pollution Bulletin, VoL 12, No. 9, pp. 305-308, 1981 Printed in Great Britain
Finnish IBP-PM group (1969). Quantitative sampling equipment for the littoral benthos (1). Int. Rev. ges. Hydrobiol. Hydrogr., 54, 185-193. Johnsson, S., Larsson, U. & Boehm, P. (1980). The gkesis oil spill. Impact on the pelagic ecosystem. Mar. Pollut. Bull., 11, 284-293. Kikuchi, T. & Tanaka, M. (1978). Ecological studies on the benthic macrofauna in Tomoe Cove, Amakusa. I. Community structure and seasonal change of biomass. Publ. Amakusa Mar. Biol. Lab., 4, 189-213. Leppakoski, E. (1973). Effects of an oil spill in the northern Baltic. Mar. Pollut. Bull., 4, 93-94. Lepp~tkoski, E. (1975). Assessment of degree of pollution on the basis of macrozoobenthos in marine and brackish-water environments. Acta Acad. Aboensis, Ser. B., 351, 1-90. Lepp~koski, E. & LindstrOm, L. (1978). Recovery of benthic macrofauna from chronic pollution in the sea area off a refinery plant, southwest Finland. J. Fish. Res. Bd. Can., 35, 766-775. Lind6n, O., Elmgren, R. & Boehm, P. (1979). The T~esis oil spill. Ambio, 8,244-253. Notini, M. (1978). Long-term effects of an oil spill on Fucus macrofauna in a small Baltic bay. J. Fish. Res. Bd. Can., 35,745-753. Pf'Lster, K. (1980). The 1979Baltic Oil Spill. Department for Environmental Protection, Ministry of the Interior. Helsinki. Segerstr/ile, S. G. (1973). Results of bottom fauna sampling in certain localities in the Tvarminne area (inner Baltic), with special reference to the so called Macoma-Pontoporeia theory. Comm. Biol. Soc. Sci. Fenn. 67, 3-12. Segerstr[tle, S. G. (1978). The negative correlation between abundances of the amphipod Pontoporeia and the bivalve Macoma in Baltic waters, and the factors involved. Ann. Zool. Fennici, 15, 143-145. Westerberg, J. (1978). Macrobenthic diversity and organic pollution in the archipelago of ~land (N. Baltic). Aqua Fennica, 1978, 70-77.
0025 -326X/81/090305 4)4 $02.00/0 © 1981 Pergamon Press Ltd.
Toxicities of Ten Metals to Crassostrea g/gas and Mytilus edulis Embryos and Cancer magister Larvae M I C H A E L M A R T I N , * K E N N E T H E. O S B O R N , 1- P A T R I C I A B I L L I G , a n d N E l L G L I C K S T E I N § *California D e p a r t m e n t o f f i s h a n d Game, Marine Pollution Studies Laboratory, 2201 Garden Road, Monterey, C A 93940, U S A +East B a y Municipal Utility District, P.O. B o x 24055, Oakland, C A 94623, USA ~:P.O. B o x 6 8 , Kelly, W Y 8 3 0 1 1 , USA §P. O. B o x 3 3 1 , Rockport, M A 01966, USA
Pacific oyster (Crassostrea g/gas T h u n b e r g ) e m b r y o s , b a y mussel (Mytilus edulis L i n n a e u s ) e m b r y o s , a n d D u n g e n e s s crab (Cancer magister D a n a ) zoea I stage larvae were exposed to arsenic, c a d m i u m , chromium, copper, lead, mercury, nickel, s e l e n i u m , silver, and zinc salts. T h e two bivalve species were exposed t h r o u g h the c o m p l e t i o n of embryogenesis (48 h), a n d the effects of the metals upon a b n o r m a l d e v e l o p m e n t were m o n i t o r e d . T h e crab larval stages were exposed to the metal s o l u t i o n s for 96 h. C o n c e n t r a t i o n s ( / a g I_ 1 as metal) which caused 50070 a b n o r m a l development in the two species of bivalve larvae and which were fatal to 50070 of the crab larvae r a n g e d from 5.3 (oyster) to 49 (crab) for copper; 5.8 (mussel) to 8.2 (crab) for m e r c u r y ; 14 (mussel) to 55 (crab) for silver; 119 (oyster) to 456 (crab) for zinc; 232 (crab) to 3000 (mussel) for
arsenic; 247 (crab) to 1200 (mussel) for c a d m i u m ; 349 (oyster) to 4360 (crab) for nickel; 476 (mussel) to 758 (oyster) for lead; 3440 (crab) to 4538 (oyster) for hexavalent
chromium; and selenium greater than 10 000 for the three species. T h e acute toxicity testing of C. g/gas e m b r y o together with two C a l i f o r n i a native species c o n f i r m e d its
usefulness for predicting toxicity to the latter species.
T h e toxicities o f trace metals to larval stages o f i m p o r t a n t m a r i n e species have b e e n reported b y a large n u m b e r o f investigators. T h e increased c o n c e r n regarding the use o f oceans as a site for the disposal o f a n t h r o p o g e n i c wastes (Eisler & H e n n e k e y , 1977), as well as the potential for increased v o l u m e s o f a n t h r o p o g e n i c wastes to C a l i f o r n i a 305
Marine Pollution Bulletin
marine waters, prompted a multispecies evaluation of selected metal toxicities to representative California species through short-term static bioassays. Eisler et al. (1978) reviewed the literature of the effects of metals and found less than one-third of the toxicity papers related to larval and embryo studies. In general, larvae or embryos prove to be less tolerant to toxic materials than adults of the same species, and hence would appear to be the critical life stages for toxicity testing (Vernberg et al., 1974; Calabrese et al., 1973). This study was undertaken: (a) to quantify the toxicities of ten metals on marine invertebrate embryos and larvae and (b) to compare the responses of two species of bivalves and one species of crustacean: Crassostrea gigas (Pacific giant oyster), Mytilus edulis (bay mussel) and Cancer magister (Dungeness crab). These invertebrate species were selected as test organisms because of their wide distribution in California, importance to its commercial fisheries, and ability of the species to be cultured in the laboratory. The metal species were selected because of their common occurrence in municipal and industrial waste effluents as well as their well known toxicity to marine organisms in general.
Materials and Methods Experiments were conducted at the California Department of Fish and Game, Marine Pollution Studies Laboratory, Big Sur, Monterey County, California, USA. Natural seawater was filtered through double 1 lam polypropylene media filters and U.V. sterilized (hereafter referred t o as' treated water'). Stock solutions of trace metals were prepared at 1000 mg 1_~ in quartz distilled water using analytical grade soluble salts: A g N O 3 , AS203, CdC12, C u S O 4 , K z C r O 7 , H g C I 2 , NiSO4 • 6H20, Pb(NO3)2, SeO2 and ZnSO4. Addition of 1 ml double-distilled HNO3 to 1 I. of metal stock solution reduced surface plating on container walls as well as increased metal solubility. Actual concentrations of stock solutions were verified against known standards and doubledistilled water blanks using a Perkin-Elmer 305 atomic absorption spectrophotometer with air-acetylene flame for Hg and Se and graphite furnace with a deuterium arc background corrector for Ag, Cd, Cu, Cr, Ni, Pb and Zn. Test solutions were prepared by appropriate volumetric dilution of stock solution with treated seawater. Results of metal concentrations are expressed as/ag 1_ ~ in excess of background. Accurate techniques to measure directly seawater background concentrations for Ag, As, Cr, Hg, Ni and Se were judged to be not available. Cd, Cu, Pb and Zn concentrations ~ g 1_ 1) for the laboratory treated water were, respectively (n=3): 0.03 +- 0.009, 0.057 +- 0.030, 0.263 +- 0.082, 0.023 +- 0.005. It could be assumed that concentrations of the non-measured chemical species were below threshold response levels of organisms, as indicated by control mortalities of < 5 °70. The laboratory seawater intake is located at least 4 km from a known or suspected point source for metals. This site is 0.5 km from a California State Mussel Watch station at Soberanes Point (Stephenson et al., 1979) and has shown low metal values. 306
Seawater water quality parameters were monitored during the experiments: pH = 8.1 +_ 0.2 (Corning Model 10); dissolved oxygen ranged from 6.5 to 8.0 mg 1_ 1 (YSI Model 57 Oxygen Meter); and salinity=33.79 +- 0.07070 (Industrial Instruments, Inc., Induction Salinometer Model No. RS-7B). Crassostrea gigas Experiments Adult Pacific giant oysters, Crassostrea gigas, obtained from Johnsons Oyster Company, Inverness, California, were thermally conditioned in the laboratory for 3-5 weeks at 20°+- I°C. Preconditioned oysters were thermally stimulated (28°-30°C) in treated seawater, and augmented with a sperm suspension (Woelke, 1972). Six to seven thousand fertilized eggs were incubated in 5% HNO 3 acidsoaked 250 ml beakers (polypropylene Tripour) for 48 h at 20 ° +- I°C. For each experiment, three replicates for each metal concentration were used. After incubation, larvae were concentrated using a 35-/am nitex screen and preserved in 10070 buffered formalin. Approximately 100 larvae were counted per test concentration under 100 x magnification. Larvae which failed to transform to the shelled, hinged 'D' shaped veliger constituted the 'abnormal' criterion. Mytilus edulis Experiments Adult bay mussels, Mytilus edulis, were obtained from American Shellfish Corporation, Moss Landing. The adult animals were received and maintained in spawning condition for up to 5 weeks in unfiltered, untreated seawater at 14 ° + 1°C. Prior to spawning, the mussels were placed in freshwater for 15 min., followed by desiccation for 2 h. The valves of the adults were then wedged open with wooden splints, applying stress to the posterior adductor muscle (after Loosanoff & Davis, 1963). The embryos were incubated at 17 °+_ 1°C for 48 h. Concentration, preservation, and abnormal criteria for the larvae were as described for C. gigas. Cancer magister Experiments First-stage zoeae of the market crab, C. magister, were provided by the California Department of Fish and Game, Marine Culture Laboratory, Big Sur, Monterey County. Zoeae I stage animals were collected within 12 h of release from the egg sponge of the adult female crab and held for 48 TABLE 1
Crassostrea gigas, Mytilus edulis, and Cancer magister. Abnormal development represented as 48 h ECs0s for oyster and mussel embryos and toxicity represented as 96 h LC50s for crab zoeae. Values are expressed as /ag 1_ 1 metal _+ 1 standard deviation. N is the number of experiments performed (with 3 replicates). Species
Toxicant
N
CuSO 4
2 3 2 3 4 3 2 3 3 3
HgCl 2 AgNO3 ZnSO4 AsO 5 NiSO 4 . 6H20 CdCI 2 Pb(NO3) 2 KzCrO 7 SeO 2
C. gigas
M. edulis
C. magister
embryos
embryos
zoeae
ECso (/agl_ I) 5.3 -+ 0.47 6.7 ± 1.55 22_+ 13.3 119_+ 12.0 326 _+ 69.9 349± 49.5 611 _+ 195.9 758 +_ 20.4 4538± 724 > 10 000
N
ECso (wgl_ L) N
2 2 2 I 1 2 1 2 2
5.8± 1 5.8_+ 1 14± 2 175 > 3000 8 9 1 - +209 1200 476-+ 1 4469± 739
3 5 4 4 1 2 1 3 1
1
> 10000
4
EC5o ~gl.-I) 49___ 19.6 8.2_+3.66 55± 20.8 456_+ 174 232 4360_+ 2205 247 575± 192 3440 > 10000
Volume 12/Number9/September 1981 LCs0 for Hg ranging from 1.0 to 3.3 tag 1_ 1. Calabrese et al. (1973) reported 48 h LCs0 for Crassostrea virginica embryos as follows: Hg (5.6 tag 1_1); Ag (5.8 tag l_l); Cu (103 tag 1_1); Zn (310 tag 1: ~); Ni (1180 tag 1_ ~); Pb (2450 tag 1_ ~); Cd (3800 tag 1_ ~)and As (7500 tag 1_ ~). Later studies by Calabrese et al. (1977) show 12-day LCso responses for C. virginica which are similar to the48 h LCs0 ofC. gigas: Hg (12 tag 1_~), Ag(25 tag 1_ ~), and Cu (33 tag 1_ ~). MacInnes & Calabrese (1978) report 48 h LC~0 values for C. virginica embryos of Hg (10.2 tag 1_ ~), Cu (15.1 tag 1_ ~), Ag (24.2 tag 1_ ~)and Zn (205 tag 1_ ~). The latter reported values for C. virginica are similar to the Statistics C. gigas responses reported herein. Woelke (1972) found the The bioassay results were analysed using the methods concentration of chemicals which did not affect embryonic described by Woelke (1972), using probit analysis (Finney, development of C. gigas at 27°C: Cu (32 tag 1_~), Hg (10 tag 1971) for estimates of ECs0s or LCs0s. 1_J), Zn (1000 tag 1_ ~), and Cr 6+ (3200 tag 1_ J). Although the criterion for 'not affected' was not described, it is evident Results that, except for Hg and Cr, the C. gigas from Woelke's experiments were approximately a factor of 10 more The acute toxicities of the trace metals to C. gigas, M. tolerant than the results of our studies. Several physical or edulis and C. magister (Table 1) are represented by mean chemical factors can affect the toxicity of specific chemicals, concentrations (48 h ECs0 or 96 h LCs0) necessary to inhibit such as temperature differences, decreased metal concendevelopment or cause mortality. The criterion of trations from adsorption to container surfaces, complexing 'abnormal' shell development in bivalve larvae represents a with organic constituents in sea water, and gaseous sublethal response that leads to certain nonrecruitment into exchange or loss (Glickstein, 1979). the population due to increased predatory pressure from Mytilus edulis embryos show toxic responses to metals longer pelagic existence. Furthermore, morphological similar to Crassostrea gigas except for Pb, Ni, Cd and As. deformities in the larvae of broadcast fertilizers can only With the exception of Pb, C. gigas is more sensitive by a result in severely decreased chances of survival for the general factor of 2. Woelke (1972) reported a similarity offspring. Finally, acute sublethal responses to mercury on in Mytilus edulis and C. gigas embryo toxic responses for larval Uca pugilator have been positively correlated with Cu, Hg and Cr, while M. edulis had one-third the tolerance chronic lethality (De Coursey & Vernberg, 1972). Selenium of C. gigas for zinc. Hrs-Brenko et al. (1977) found Mytilus did not produce a dose response in bivalve embryos or crab galloprovincialis embryos had optimal development at a larvae at concentrations less than 10 000 tag 1_ 1. salinity of 34.8 %00and temperature of 15.6 °C. The effect of The responses ofC. gigasembryos to the 10 metals ranged over four orders of magnitude. The most toxic metals, lead was minimal in optimal salinity and temperature conditions at concentrations up to 1000 tag 1_ ~, although at expressed as 48 h ECs0, were copper (5.3 tag !_ ~), mercury (6.7 tag |_ ~), and silver (22 tag l_ ~). C. gigas embryos were the higher concentrations it caused a delay or inhibition of least affected by hexavalent chromium (ECs0 = 4538 tag l_ ~) embryonic development. Cancer magister zoeae are more sensitive to copper, and selenium (> 10 000tag 1_ ~). cadmium and zinc than are crab larvae of an Australian M. edulis embryos show a similar pattern of response to species (Paragrapsus quadridentatus), by a factor of trace metal toxicity as with C. gigas. Mercury, copper and silver are the most toxic with 48 h ECs0 values of 5.8 tag 1_ 1 approximately three (Ahsanullah & Arnott, 1978). The 48 h LCs0 for Carcinas maenas larvae was 10 tag 1_ ~(Hg) and 330 for the first two metals and 14 tag 1_ ~ for silver. Under experimental conditions, the bay mussels embryos show the tag 1_ j (Cu)(Conner, 1972). Rosenberg & Costlow (1976) reported a decreased survival and significant delay in following rank order of toxicity: Hg and Cu > Ag > Zn > development from megalopa to third stage of blue crabs P b > N i > C d > A s > C r > Se. (Callinetes sapidus) in 50 tag 1_~ Cd over four salinity The 96 h LC~o values of Cancer magister correspond to the pattern shown by those of Crassostrea gigas, with certain regimes. Mirkes etal. (1978) report that 10 tag 1_ t Cd for 24 h exceptions. In the bivalve larvae, copper and mercury elicit exposure caused a 20% mortality (= LC20) for the mud crab, almost identical responses at very low concentrations Eurypanopeus depressus, in zoeae I larvae. Woelke (1972) proposed the use of C. gigas embryo while Cancer magister is more sensitive to mercury (LC50=8.2 tag 1- ~) than copper (LC50=49 tag 1_~). Silver, bioassays as a water quality criterion for the protection of with an LCs0 of 55 tag 1_ ~, has almost the same toxicity as marine resources. One often stated criticism of the use of copper in C. rnagister. Cancer magister zoeae are more laboratory obtained toxicity data is that it fails to consider sensitive to cadmium and arsenic than Crassostrea gigas. adequately 'natural detoxifying' mechanisms, such as Cancer magister is an order of magnitude more tolerant of particulate concentration or organic content, of the nickel (4360 tag l_q than both species of bivalve larvae receiving water. It is our opinion that regulatory authorities should adopt water quality criteria that reflect 'worse case' tested. conditions, and individual field situations should be considered, on a case-by-case basis, backed by factual Discussion information. The difficulty in a laboratory experiment to The responses of the three invertebrate marine species duplicate the multi-factoral variables found in field tested compared favourably with other toxicity testing situations is obvious. results. Conner (1972) found Ostrea edulis larvae had a 48 h The testing procedures of these studies allows a
h (15 _+ 1°C) to allow acclimation. Handling of zoeae was by large bore capillary tubing (4 mm) to minimize handling stress. Five zoeae were placed in 251Yml glass beakers and fed 200 freshly hatched brine shrimp nauplii per ml of culture solution, initially, and at 48 h of exposure. Twenty zoeae were tested per experimental concentration. Mortalities were recorded at 24, 48, 72 and 96 h of exposure to toxic solutions. An opaque, non-motile individual was the lethal response criterion.
307
Marine Pollution Bulletin comparison of two native California invertebrate marine species, of commercial, economic and ecological importance. Not surprisingly, the embryos of the bivalve
M y t i l u s edulis s h o w s a s i m i l a r r e s p o n s e t o all m e t a l s e x c e p t f o r a r s e n i c (9.2 x m o r e t o l e r a n t ) , silver a n d l e a d ( a l m o s t 2 x m o r e sensitive). T h e D u n g e n e s s c r a b s h o w s w i d e r v a r i a t i o n in r e s p o n s e s t o m e t a l s ; it is m o r e t h a n t w i c e as s e n s i t i v e t o c a d m i u m as t h e o y s t e r , as well as slightly m o r e sensitive t o a r s e n i c , lead a n d c h r o m i u m . T h e c r a b is s i g n i f i c a n t l y m o r e t o l e r a n t o f zinc (3.83 x ) , c o p p e r ( 9 . 2 5 x ) a n d n i c k e l (12.49 × ) t h a n t h e oyster. W i t h t h e r e c o g n i t i o n t h a t c e r t a i n species d i f f e r in r e s p o n s e t o m e t a l s , t h e P a c i f i c o y s t e r e m b r y o b i o a s s a y a p p e a r s t o h a v e m e r i t as a n ' i n d i c a t o r ' o r ' s t a n d a r d ' m a r i n e b i o a s s a y species in C a l i f o r n i a .
Ahsanullah, M. & Arnott, G.H. (1978). Acute toxicity of copper, cadmium, and zinc to larvae of the crab Paragrapsus quadridentatus (H. Milne Edwards), and implications for water quality criteria. A ust. J. mar. Freshwat. Res., 29, 1-8. Calabrese, A., Collier, R. S., Nelson, D. A. & Maclnnes, J. R. (1973). "Ihe toxicity of heavy metals to embryos of the American oyster Crassostrea virginica. Mar. Biol., 18,162-166. Calabrese, A., MacInnes, J. R., Nelson, D. A. & Miller, J. E. (1977). Survival and growth of bivalve larvae under heavy metal stress. Mar. Biol., 41,179-184. Conner, P. M. (1972). Acute toxicity of heavy metals to some marine larvae. Mar. Pollut. Bull., 3, 190-192. DeCoursey, P. J. & Vernberg, W. B. (1972). Effect of mercury on survival, metabolism and behaviour of larval Uca pugilator (Brachyura). Oikos, 23, 241-247.
Eisler, R. & Hennekey, R. J. (1977). Acute toxicities of C d 2+, C r 6+, Hg z +, Ni 2 + and Zn 2 + to estuarine macrofauna. ArchsEnvir. Contain. Toxic., 6, 315-323. Eisler, R., O'Neill, D. J., Jr. & Thompson, G. W. (1978). Third annotated bibliography on biological effects of metals in aquatic environments. (No. 1293-2246). U.S. Environmental Protection Agency Report 600/3-78-005. Finney, D. J. (1971). Prob# Analysis. Cambridge University Press, London. Glickstein, N. (1979). The potential loss of dissolved mercury and selenium in marine experimentation. Mar. Pollut. Bull., 10, 157. Hrs-Brenko, M., Claus, C. & Bubic, S. (1977). Synergistic effects of lead, salinity, and temperature on embryonic development of the mussel Mytilus galloprovincialis. Mar. BioL, 44, 109-115. Loosanoff, V. L. & Davis, H. C. (1963). Rearing of bivalve mollusks. In Advances in Marine Biology (F. S. Russel, ed.). Academic Press, London. Maclnnes, J. R. & Calabrese, A. (1978). Response of the embryos of the American oyster, Crassostrea virginica, to heavy metals at different temperatures. I n Physiology and Behavior of Marine Organisms (D. S. McLusky and A. J. Berry, eds.). Pergamon Press, New York. Mirkes, D. Z., Vernberg, W. B. & DeCoursey, P. J. (1978). Effects of cadmium and mercury on the behavioral responses and development of Eurypanopeusdepressus larvae. Mar. BioL, 47, 143-147. Rosenberg, R. & Costlow, J. D. Jr. (1976). Synergistic effects of cadmium and salinity combined with constant and cycling temperatures on the larval development of two estuarine crab species. Mar. Biol., 38, 291-303. Stephenson, M. D., Martin, M., Lange, S. E., Flegal, A. R. & Martin, J. H. (1979). California Mussel Watch 1977-1978. Volume II. Trace metal concentrations in the California mussel, Mytilus californianus. State Water Resources Control Board, Sacramento. Water Quality Monitoring Report No. 79-22. Vernberg, W. B., DeCoursey, P. J. & O'Harra, J. O. (1974). Multiple environmental factor effects on physiology and behavior of the fiddler crab, Uca pugilator. I n Poilu tion and Physiology of Marine Organisms (F. J. Vernberg and W. B. Vernberg, eds.). Academic Press, New York. Woelke, C. E. (1972). Development of a receiving water quality bioassay criterion based on the 48-hour Pacific oyster, Crassostrea gigas, embryo. Wash. Dept. Fish. Tech. Rept., 9, 1-93.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 308-314, 1981 Printed in Great Britain
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Plutonium Occurrence and Phase Distribution in Sediments of the Wyre Estuary, Northwest England S. R. A S T O N , * D. J. A S S I N D E R , D. A . S T A N N E R S * a n d J. E. R A E + D e p a r t m e n t o f E n v i r o n m e n t a l Sciences, University o f Lancaster, L a n c a s t e r L A 1 4 YQ, U K *Present address: International Laboratory of Marine Radioactivity, Mus~e OeOanographique, Monaco * Present address: Radiochernistry Division, J.R.C., Ispra 21020, Varese, Italy * Present address: Department of Geology, University of Reading, Reading, UK
The occurrence of plutonium isotopes derived from the Windscale reprocessing facility discharges and weapons test fallout in intertidal sediments of the Wyre estuary, northwest England, is reported. Windscale plutonium appears to be slowly transported to the estuary in association with sedimentary material, and its distribution in surface and buried sediments is controlled by the variations in organic matter content of the sediments and/or their 308
grain size characteristics. Results from chemical leaching experiments suggest that very little plutonium is ion exchangeable or in humic substances, but it is in other organic and Fe/Mn hydrous oxide fractions of the sediments. Plutonium shows a similar depositional behaviour to mercury which enters the Wyre directly in local industrial discharges.