Environ. Sci. Technol. 1991, 25, 956-963
Mean Daily Discharge of the Passaic River a t Little Falls, New Jersey (Station 01389500), 1940-1988; U S . Geological Survey, personal communication. Bopp, R. F.; Simpson, H. J. Contamination of the Hudson River: The Sediment Record. In Contaminated Marine Sediments: A.sscssment and Remediation; National Academy Press: Washington DC, 1989; p p 401-416. Suszkowski, D. J. Ph.D. Thesis, University of Delaware, Newark, DE, 1978. Olsen, C. R.; Cutshall, N.H.; Larsen, I. L.; Simpson, H. J.; Trier, R. M.; Bopp, R. F. Geo-Mar. L e t t . 1984-1985, 4 ,
15F160. ( 2 8 ) Assessment of Pollutant I n p u t s t o Neu; York Bight; Job Number DYNM0100; HydroQual, Inc.: Mahwah, NJ, 1989.
Received for revieu August 9, 1990. Revised manuscript received December 26, 1990. Accepted J a n u a r y 4, 1991. This research u a s supported by the Neu: Jersey Department of Environmental Protection (Contracts P 24096 and P50582), the National Science Foundation (Grant CHE-8620177), and t h e Hudson River Foundation (Grant NlJDlOIn’I86HIOOI~.
Phenyltins in Water, Sediment, and Biota of Freshwater Marinas Karl Fent” and Judith Hunn Swiss Federal Institute for Water Resources and Water Pollution Control (EAWAG), CH-6047 Kastanienbaum, Switzerland I A series of phenyltins and butyltins were determined
in the water column, sediment, and biota of two freshwater marinas of Lake Lucerne, Switzerland. Considerable concentrations of triphenyltin (TPT), diphenyltin (DPT), and monophenyltin (MPT) were found for the first time in all the compartments. In addition, tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) occurred in significant concentrations. During 1988-1990, aqueous T B T concentrations followed a seasonal pattern with increases of up to 752 ng/L in late spring, followed by a successive decrease until winter, when concentrations remainded around 100 ng/L. TPT and T B T concentrations decreased during the observation period. Of the total aqueous TBT, 95-99% was present in the dissolved phase. In mussels Dreissena, TPT and T B T residues ranged up to 3.88 and 9.35 pg/g, respectively. Vertical sediment core profiles showed highest TPT and T B T concentrations of up to 107 and 2043 pg/kg, respectively, in the top with decreasing values with depth. Dating of the core and the occurrence of only low concentrations of DBT and MBT indicate that T B T is conserved in these sediments over a time period of years. Introduction
Organotin compounds are entering the marine and freshwater environment from their use in antifouling paints. Small amounts of these biocides are released continously from vessels into the water, thereby preventing attachment of organisms. Municipal and industrial wastewater, sewage sludge, and landfill leachates are additional organotin sources (1,2). Thus far, attention has mainly been given to tributyltin (TBT), although triphenyltin (TPT) has also been employed as a cotoxicant with T B T in some long-performance antifouling paints. Contamination of aquatic systems by TPT and the aquatic toxicity of this compound are only little known. TPT and T B T are both highly toxic to aquatic life (3). T B T is particularly toxic to molluscs (oysters) and gastropods (3-8), leading to declines of dog whelk populations on various coasts (8). Chronic toxic effects on oysters (shell deformation) (9) and marine gastropods (sterilization of females) occur a t aqueous concentrations of a few nanograms per liter (8),and most susceptible marine algae (10, 1 1 ) and zooplankton species (12-14) were negatively affected at a few hundred nanograms per liter. In contrast to TBT, concentrations of TPT in the marine and freshwater environment are fairly unknown. In-
* Present address during sabbatical leave: Woods Hole Oceanographic Institution, Department of Biology, Woods Hole, MA 02543. 956
Environ. Sci. Technol., Vol. 25, No. 5, 1991
creased levels of T B T in water, sediment, and biota have been linked primarily to boating activities. In the water column, T B T residues were reported to lie in the high nanograms per liter range for seawater marinas, and in the low to medium nanograms per liter range for open water (9, 15-19). T B T residues in the sediments were found to be considerably higher, typically in the range of -200-1000 p g / k g (15-17), with decreasing levels with depth (20). In water, degradation of TPT and T B T takes place. TPT was shown to be photodegraded to diphenyltin (DPT) (21), and T B T was biodegraded by successive dealkylation reactions leading to dibutyltin (DBT) as the principal degradation product with lesser amounts of monobutyltin (MBT) (22,231. In sediments, T B T degradation was reported to be much slower with half-lives of 4--5.5 months (20, 22).
To date, little is known about the occurrence, temporal variation, and behavior of organotin compounds in freshwater systems (15-1 7), especially in respect to phenyltins. The purpose of this study was to determine Ihe presence, partitioning, and fate of phenyltins and butyltins in different compartments of freshwater marinas and detect and monitor seasonal variations and trends throughout 1988-1990. The results document for the first time a series of phenyltin residues in water, sediment, and biota. Although the origin of TPT is attributed to antifouling paint leachates, this compound has a growing importance as an agricultural pesticide prone to contaminating the aquatic system by leaching and runoff. This suggests that the presented findings are applicable to more than this particular site. Our study also gives for the first time detailed phenyltin and butyltin sediment profiles in conjunction with 137Csprofiles. The sedimentary record suggests that TBT is conserved in these sediments over time periods of years. Experimental Section
Study Sites and Sampling Procedure. During 1988, 1989, and 1990, samples were taken in the 2.5-3 m deep marinas Lucerne (SEG) and Stansstad (STA) of the oligotrophic Lake Lucerne, located in the central part of Switzerland (Figure 1). The marinas were selected on the basis of different size and construction. Marina SEG was constructed in 1978, has berths for 456 vessels, and is well flushed. Marina STA has berths for 242 vessels, was constructed in 1965, and has a narrow entrance resulting in poor flushing. Water samples were always collected at the same location within the marinas adjacent to the vessels at midmonthly intervals. A stainless-steel sampler or a 2.7-L glass bottle was used and filled at 1 m below the
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Map of Switzerland and Lake Lucerne. Sampling locations and sites ().
Stansstad (STA).
surface. The water was either analyzed immediately or acidified with hydrochloric acid to pH 1-2, preserved with 0.1% formaldehyde, and stored at 4 "C in the dark in 1-L glass bottles in 1988 and in 2.5-L polycarbonate bottles thereafter. Prior to use, the glass bottles were washed in detergent and rinsed with deionized water, acetone, methanol, and diethyl ether. Marina sediments were anoxic. Sediment cores of 12-cm diameter and up to 40 cm in depth were taken in both marinas in July 1989 with a gravity corer using Plexiglass tubes. Immediately after collection, sediment from the cores was extruded in 0.5- or 1-cm slices, split vertically into two subsamples, and stored in cleaned glass jars a t -30 'C. The overlying water of the sediment cores collected was acidified and preserved for analysis. One portion of wet sediment was used for sediment organotin analysis. Two to three aliquots of individual slices (5-15 g wet weight) were analyzed and mean values are given on a dry weight basis. The other wet suhsample was freezedried and used for determination of water content, organic and inorganic carbon content, and 'Ws y-counting. Samples of freshwater mussels (Dreissena polyrnorphn) were collected in August 1989 by hand in SEG at the marina entrance and at the sampling site. In marina STA, mussels were collected approximately 10 m apart from the
I
within each marina. (1) marina Lucerne (SEG): (2) marina
sampling site. Shell length of the mussels were recorded. A fish (Leuciscus cephnlus) was caught in January 1990 in marina Murten, Lake Murten, and the muscle tissue was dissected for analysis. All the samples were stored at -30 'C prior to analysis. Analytical Procedure. The organotin analysis of water and sediment samples is based on the procedure of Muller and it speciates between trace amounts of butyltins (MBT, DBT, TBT), phenyltins (MPT, DPT, TPT), and tricyclohexyltin. The method has also been extended to the analysis of particulate matter (2, 24). Briefly, the procedure consisted of four steps: (i) acid digestion of the sample; (ii) extraction; (iii) derivatization (ethylation by a Grignard reaction); (iiii) analysis by a Carlo Erba HRGC 5160 gas chromatograph equipped with an on-column injector, a fused-silica capillary column (30-m length, 0.32mm id., film thickness 0.25 pm; DB-5) and a Carlo Erba flame photometric detector SSD 250. The detector was operated without a filter and with a hydrogen-rich flame. For quantification, internal standards (IS) tripropyltin chloride and mono-, di-, tri-, and tetrapentyltin chloride were employed and added to the samples prior to extraction. Pentyltin chlorides were prepared according to ref 2, where details of the analytical procedure for water and particulates samples are given. For the partitioning
(In,
Environ. Sci. Technol.. Vol. 25, No. 5. 1991 957
Marina SEG 200 1988
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4 5 6 7 9 2 3 4 5 6 7 B 9101112
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Flgure 3. Concentrations of lriphenykin (TPT) in unfikered marina waters during 1988 and 1989. 20
10
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Figure 2. Typical W F U chromatogram of an unfikered water sample (STA. August 9. 1989)(top)and a sediment sample ( m e SEG) (below) spiked with five internal standards: S1. tripropykin; S2. monopentykin: 53,dipentyitin: 54, tripentyllin; S5. tetrapentyltin. MBT. monobutyttin; DBT. dibutykin: TBT. tributykin: MPT, monophenyln: DPT. diphenykin: TPT. triphenyltin. All organotin compounds were ethylated species.
study, lake water was filtered through Nuclepore polycarbonate filters (pore size 0.4 pn) for the separation of suspended particles and dissolved water phase. Filtrate and particulates were analyzed separately. Biological Samples. Samples of mussels were divided according to shell length into small and large size individuals. The animal tissue was removed from the shell and combined samples of 1 g wet weight were analyzed. In marina SEG, 18 small mussels (shell length 10-15 mm), and five large mussels (18-25 mm) that were collected a t the marina entrance, and nine mussels from the sampling site with various sizes (9-18 mm) were pooled. In marina STA, only small mussels (10-13 mm) were found, and 21 individuals were pooled. Of the fish muscle tissue, 8 g was used for analysis. The samples were homogenized and acidified with HCI to pH 2, and IS were added. Diethyl ether containing 0.25% tropolone was used for extraction. The homogenates were rigorously mixed and centrifuged and the extract was decanted. The further procedure was identical with that for sediment samples. Recoveries for every organotin species, typically 50-70% in water, and 60-95% in particles, sediment, and biota, were determined in each analytical sample. The detection limit for the phenyl- and butyltins was 1-10 ng/L of water, depending on the organotin compound, 0.05-2 Ng/kg (dry weight) of sediment, depending on the sample volume, and 9-23 ng/g (wet weight) for hiological samples. The con958
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centrations reported are usually mean values of duplicate or triplicate determinations, refer to the phenyl- and butyltin species as the ion, and were corrected for recovery by IS.
Results and Discussion Phenyltins in the Water Column. A series of phenyltins and hutyltins were detected in marina waters. Figure 2 illustrates a typical gas chromatogram of an unfiltered water sample containing mono-, di-, and triphenyltin and mono-, di-, and tribntyltin. Tricyclohexyltin, which is used as a pesticide in agriculture, was not detected. TPT was detected in most samples of both marinas during 1988 and 1989 in concentrations of up to 191 ng/L (Figure 3). Mono- (MPT) and diphenyltin (DPT), probably breakdown products of TPT (22, 25), were detected in some of the samples, predominantly a t higher TPT concentrations (Figure 2). Phenyltins did not occur in 1990, however. T o our knowledge, these measurements are the first documentation of phenyltin residues in freshwater systems. TPT most likely originates from antifouling paints, since at the sampling sites agricultural applications can be rnled out. In Switzerland, this compound has been used in some older paints, usually as a cotoxicant with TBT, but it was banned in 1990. TPT is also employed in marine antifouling paints in Japan. However, after its regulation in antifouling paints, this compound may contaminate aquatic systems via runoff, due to its growing importance in agricultural applications. Butyltins i n the Water Column. Butyltins, TBT, DBT, and MBT, were found in every sample throughout the 3-year period. Figure 4 shows the butyltin concentrations in marina SEG. T B T was the predominant organotin species, showing a characteristic seasonal distribution throughout the years. Concentrations rose sharply
Marina STA 1988
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Figure 4. Concentrations of butynins in unfiltered water samples of marina SEG during 1988. 1989, and 1990.
Figure 5. Concentrations of butyltins in unfiltered water samples of marina STA during 1988, 1989, and 1990.
in spring due to the freshly painted boats that are launched, with highest levels in early May 1988 (752 ng/L) and late April 1989 (440 ng/L) and 1990 (245 ng/L). Aqueous TBT concentrations decreased successively during the summer to reach minimal and usually relatively constant values in the range of 77-127 ng/L during the winter. Thus, the rate of decrease slowed or was absent during the cold season. Boating activity ceased in November, and up to a half of the boats were taken on land during the winter. A second TBT peak in September 1989 and 1990 is likely due to an additional T B T input, prohably from boats that were cleaned and/or repainted. Thus, seasonal trends in contamination coincided with boat usage patterns and with the leaching behavior of antifouling paints. Figure 5 shows the seasonal distributions of butyltins in marina STA exhibiting a similar pattern as in SEG. Maximal T B T concentrations were found in June 1989 (571 ng/L) and April 1990 (254 ng/L), with a similar decrease during the summer. In September 1990, a second peak occurred. Although approximately half the vessels
were moored in marina STA than were in SEG, average T B T concentrations were similar. This is mainly attributed to the slower flushing rate of this marina, resulting in a reduced dilution into the surrounding lake. Concentrations of TBT in both marinas showed a decreasing trend over the 3-year period, likely resulting from the regulation of organotin-containing antifouling paints in Switzerland. Regulation was announced in 1988, and in 1989, only a few of these paints were left on the market. As of July 1,1990, these paints are banned. The TBT concentrations found in these marinas are in the range of values reported in freshwater systems in Canada (15,16), but are significantly higher than in the open lake or in Swiss rivers (17). The concentrations are similar to values found in seawater marinas and estuaries with heavy boating and shipping traffic, ranging from approximately 50 ng/L to several micrograms per liter (9,15,18,19). In open, well-flushed regions of bays and estuaries, concentrations were generally less than 20 ng/L. DBT and MBT, likely breakdown products of TBT, were present in only low concentrations in both marinas, Environ. Sci. Technol.. VoI. 25. No. 5, 1991 959
Table I. Concentration of TBT in Unfiltered Water and in the Dissolved and Particulate Phase, Distribution Ratios (Kd)
marina SEG
date (1989)
total," ng/L
dissolv,* ng/L
partic,' mg/kg
Kd (X103)
Apr 20 May 16 June 13 July 12
440 328 289 252 229 380 320 338 571 543 245 245
385 304 261 248 283 339 228 311 556 417 193 153
1 1 1
