SPATIAL AND TEMPORAL OF B U T Y L T I N CHESAPEAKE LENWOOD

W. HALL

DISTRIBUTION

COMPOUNDS

BAY MARINA

IN A N O R T H E R N AND RIVER SYSTEM

J r . * , S T E V E N J. B U S H O N G , and W. S C O T T H A L L

W. E D W A R D

JOHNSON,

The Johns Hopkins University, Applied Physics Laboratory, Aquatic Ecology Section, Shady Side, Maryland, U.S.A.

(Received November 1987) Abstract. This study was designed to: determine dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TTBT) bi-weekly for a four m o n t h period (June-September 1986) in the Port Annapolis Marina, Mears Marina, Back Creek and Severn River area of Northern Chesapeake Bay; measure DBT, TBT and TTBT for five successive days (Thursday-Monday) to determine possible daily effects (weekday versus weekend) and determine DBT, TBT and T T B T every two hours for one full tidal cycle in the study area. M a x i m u m concentrations of TBT were reported at both Port Annapolis Marina (1801 ng L ~) and Mears Marina (1171 ng L - J) during early June followed by significant reductions in TBT during late s u m m e r and early fall. All 4 Back Creek Stations also had highest concentrations of TBT in early June; significant reductions occurred during the next three months. The highest concentration of TBT reported in the Severn River (48 ng L - ~) occurred in September. The lowest TBT value (5 ng L - ~) at this station occurred in June. T T B T was not detected in any of the samples. The day of week sampled (Thursday-Monday) during the daily experiments was not found to significantly affect TBT concentrations. TBT evaluations every two hours during the tidal cycle demonstrated that values peaked at 1400 and 1600 hr time intervals. Peak concentrations of TBT occurred during a rising tide. The possible consequence of the measured TBT concentrations for aquatic biota are discussed.

Introduction Organotin compounds have been promoted in recent years due to their excellent antifouling action, long lifetimes and lack of corrosion qualities. The use of organotin coatings, such as tributyltin (TBT), on a wide variety of both recreational and commercial watercraft in Chesapeake Bay has increased in recent years (U.S. EPA, 1983; Hall et al., 1987). The increased use of TBT paints in Chesapeake Bay presents environmental problems due to the potential toxicity to non-target aquatic organisms. TBT has been reported toxic to aquatic biota at ng L-~ concentrations (U'ren, 1983; Beaumont and Budd, 1984; Walsh et al., 1983; Bryan et al., 1986). Hall et al. (1987) conducted a 12 month study to evaluate TBT and other butyltin species monthly in the surface microlayer (water surface) and water column of eight locations (marinas, river systems, etc.) in the Maryland waters of Chesapeake Bay. Sampling sites included a total of four large and small marinas, a large harbor, two background rivers and a heavily used shipping channel. The highest TBT concentration reported in the water column for any station was 998 ng L-~ in the Port Annapolis Marina (Back Creek). Surface microlayer concentrations of 1049 ng L - 1 * To whom correspondence should be addressed.

Environmental Monitoring and Assessment 10 (1988) 229-244. 9 1988 by Kluwer Academic Publishers.

230

I.ENWOOI) w . HALL, .W. ET AL

were also reported in this marina. TBT concentrations in the Port Annapolis Marina area were generally higher than the other study sites. Due to the TBT concentrations reported in Port Annapolis Marina, an extensive four month study was initiated in this area in June of 1986. The objectives of this study were to: determine dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TTBT) bi-weekly for a four month period at seven sampling stations in the Back Creek and Severn River area; measure TBT and the other butyltin species at three of the seven stations for 5 successive days (Thursday through Monday) to monitor possible daily fluctuations in their concentrations and determine TBT and the other butyltin species every 2 hours for one full tidal cycle (13 hr) at three of the seven stations to momtor possible fluctuations due to tide. DBT and TTBT were evaluated in this study; however, TBT was the most environmentally important butyltin compound evaluated because it is much more toxic to aquatic biota (Laughlin and Linden, 1985). The Back Creek study area contains 13 marinas and has a high level of boating activity. TBT found in this study area would likely result from boating activity because there are no other major sources of TBT in Back Creek. Back Creek flows into the Severn River which contains several natural oyster beds. Larval stages of oysters have been shown to be particularly sensitive to TBT at ng L - 1 concentrations (His and Robert, 1980; His and Robert, 1985; Thain and Waldock, 1986). Materials and Methods

DBT, TBT and TTBT concentrations were measured bi-weekly at seven stations over a four month period (June-September, 1986) in the Back Creek - Severn River area. Sampling stations were representative for the flow of water from Back Creek into the Severn River (Figure 1). Stations 1 and 3 were located at Port Annapolis Marina and Mears Marina, respectively. These are the two largest marinas in Back Creek with approximately 250-300 boat slips each. Stations 2, 4, 5, and 6 were located in Back Creek. Station 7 was in the Severn River, approximately 400 m down stream from the confluence with Back Creek. All bi-weekly sampling was conducted on the falling tide (1-11/2hr after high tide) on either a Monday or Tuesday. To monitor potential daily or tidal fluctuations in TBT concentrations, two additional short-term studies were conducted. Possible daily changes in butyltin concentrations (i.e. weekday versus weekend differences) were evaluated at three of the seven stations (Stations 1, 4, and 7) for a 5-day period (Figure 1). Sampling was conducted during the falling tide on August 7-11, 1986 (Thursday through Monday). Sampling was performed every two hours for one full tidal cycle (13 hr) to monitor possible tidal influences on butyltin concentrations. Sampling for tidal influences was conducted on September 3, 1986 at Stations 1, 4, and 7 (Figure 1). Triplicate water samples were collected at each station during all experiments. A sample was taken by lowering a one liter polycarbonate container (Nalgene) at arm's length in the water. The top of the container was then removed and the sample

231

SPATIAL AND T E M P O R A L DISTRIBUTION OF BUTYl.TIN C O M P O U N D S

: ,'.='i

9

9 :~ ." .;'~,~

|

|

|

MEARS MARINA

|

':~ -',-~2

PORT ANNAPOLIS~',il MARIN~ BACK CREEK o~. .:~,.~i:

~ 9

9

-i

.

SEVERN RIVER

"Yt

~,.

-

--~

Fig. 1.

Map of 7 sampling stations in the Port Annapolis Marina, Back Creek and Severn River study area.

collected. Samples were taken from a dock at Port Annapolis Marina (Station 1). At all other stations, samples were collected from a small boat that had not been treated with any type of antifouling paint. Deionized water in polycarbonate containers was carried into the field as blank. After collection, all samples were placed on ice in the dark for transport and subsequently stored in a freezer.

232

LENWOOD W. HALL, Jr. ET AL

Standard water quality parameters of temperature, dissolved oxygen, pH, salinity and conductivity were measured at each station. Depth measurements was also reported during each sampling period. Wind velocity and direction was determined with an electronic wind speed indicator (Davis Instruments). Unfiltered water samples were analyzed for DBT, TBT, and TTBT. An ultra-trace method consisting of simultaneous hydridization with sodium borohydride and dichloromethane extraction was used (Matthias et al., 1986). Butyltins were quantified using a Tracor 560 gas chromatograph equipped with a flame photometeric detector. Detection limits of 5 ng L - 1 as TBT were achieved. A minimum of two out of three samples were analyzed at each station. Periodically, replicates were analyzed from individual samples and some samples spiked with DBT, TBT and T T B T standards. Spiked samples confirmed no interference due to the sample matrix. Data were analyzed using two-way factorial Analysis of Variance (ANOVA) with location and date (or time) as the factors. The model for this analysis was:

Y(i, j, k)=/z + a(i)+ b ( j ) + a b ( i , j ) + e(i,j, k) where ~t =overall mean a =location effect b = d a t e (or time) effect ab =location by date (or time) interaction e = r a n d o m error. Duncan's Multiple Range Test was used to determine the rank of location and date (or time) means (Walpole and Myers, 1972). Means that were significantly different from each other were identified. Results W A T E R Q U A L I T Y AND W I N D P A R A M E T E R S

Water quality data for the bi-weekly, daily and tidal sampling are presented in Table I. The following ranges were reported for each parameter during the three studies: temperature = 21.5-29 ~ dissolved oxygen = 2.8-12.8 mg L - l ; pH = 7.7-8.8; salinity = 8.5-13.9%0; conductivity = 13 560-21 200 umhos/cm and depth = 1.0-3.75 m. Wind parameters reported during the bi-weekly, daily and tidal studies are presented in Table II. These parameters were evaluated to assess the possible effect of wind on TBT distribution in the study area. Wind strength was classified as light ( < 2 m s e c - l ) , moderate (2-3 m sec-1) and strong ( > 4 m sec-1). Wind strength was moderate approximately half of the time. The wind direction was highly variable in Back Creek and occasionally changed during the sampling period. Wind direction may have influenced the flushing or distribution pattern of TBT in some instances; however, a consistent pattern was not apparent.

TABLE 1

Total

4 7 1 4 7

1

25.1(21.5-28) 24.8(21.5-28) 27.8(27-28) 27.7(27-28) 27(27) 22.9(22.5-23.5) 22.7(22-23) 22.7(22-24)

6 7

Daily

25.6(22-28) 25.6(22-29) 25.6(22-29) 25.5(22-28.5) 25.6(22-29)

1 2 3 4 5

Bi-weekly

T (C)

Station

Study

8.7(6.4--10.6) 8.0(5.0-10.2) 4.8(2.8-5.5) 6.3(5.3-7.3) 5.6(4.8-6.2) 7.1(5.8-9.2) 8.6(7.9-9.6) 10.4(8.7-12.8)

8.4(4.4-12.5) 8.3(5.5-10.6) 8.9(5.4-11.7) 8.5(5.0-10.6) 8.4(5.3-10.4)

Dissolved Oxygen (mg L- l)

8.2(7.9-8.4) 8.1(7.7-8.4) 8.0(7.6-8.0) 8.2(8.0-8.4) 8.0(7.8-8.2) 8.3(7.9-8.7) 8.4(8.2-8.5) 8.4(8.2-8.6)

8.3(7.7-8.8) 8.3(7.7-8.6) 8.3(7.9-8.7) 8.2(7.8-8.4) 8.2(7.9-8.4)

pH

10.9(9.0-13.7) 11.0(8.6-13.9) 9(8.0-10.0) 9(8.5-9.5) 9.3(8.8-9.5) 10.4(10.2-11.3) 10.5(10.1-11.0) 10.7(10.5-11.0)

10.5(9.2-13.2) 10.6(9.0-13.1) 10.6(9.0-13.2) 10.6(9.0-13.2) 10.7(9.0-13.5)

Salinity (%0)

Water Quality

18230(14560-21000) 18 110(13 560-21 200) 15280(13800-165130) 16000(15500-17000) 16 200(15 50(o16 800) 16190(160(o-16500) 16270(16000-16800) 16590(16200-172130)

17 700(15 400-20 800) 17 840(15 080-20 540) 17900(15 100-20800) 17860(15020-20800) 17970(14960-21 000)

Conductivity /lmhos cm- J

2.5(2.25-2.75) 3.1(3,0-3.5) 3.1(3.0-3.5) 3.2(2.5-3.5) 3.1(2.75-3. 75) 3.2(2,75-3.5) 1.5(1.0-2.5) 2,7(2.5-2.75) 3.3(3.25-3.5) 1.1(1,0-1.25) 2.6(2.25-2.75) 3.2(3.0-3.25) 1.3(1.0-1.75)

Depth (m)

Water quality data for each station reported during the bi-weekly, daily and tidal studies. Mean values and ranges are reported for each parameter

234

LENWOOD W. HALL, Jr. ET AL FABLE 11 Wind parameters reported during the bi-weekly, daily and tidal studies. Both wind strength (m sec- ~) and wind direction were reported. Wind strength was classified as light ( < 2 m sec ~), moderate (2-3 m sec - t ) and strong ( > 4 m sec- J) Study

Date

Wind strength (m sec ~)

Wind direction

Bi-weekly Bi-weekly Bi-weekly Bi-weekly Bi-weekly Daily Daily Daily Daily Daily Bi-weekly Bi-weekly Tidal Bi-weekly Bi-weekly

6/3/86 6/16/86 6/30/86 7/14/86 7/28/86 8/7/86 8/8/86 8/9/86 8/10/86 8/11/86 8/12/86 8/26/86 9/3/86 9/9/86 9/22/86

moderate strong moderate strong moderate light moderate moderate light moderate strong moderate light light moderate

W-SW SW NE W NE S W-SW W-SW E-NE W-NW N-NE W-NW-NE ~ E-NE NW-SE b E

a Wind direction was variable in the creek. h Wind direction changed from NW to SE during course of sampling.

BI-WEEKLY SAMPLING

DBT and TBT concentrations reported during the bi-weekly sampling are reported in Table III. TTBT was not detected at any of the Stations. Maximum concentrations of DBT (477 and 666 ng L - 1) were greatest in early June at both marina Stations (1 and 3). DBT decreased at these two marina stations during the summer and early fall. The highest concentration of DBT, 418 ng L - 1, in the four Back Creek stations (2, 4, 5, and 6) was reported during June. DBT decreased at these four stations during the four month study. DBT was lower (5 ng L - l) at Station 7 (Severn River) during early June with a peak concentration (48 ng L - 1) reported in September. DBT was less than TBT at Stations 1-5 when mean station values were calculated by averaging across dates (Table IV). However, DBT was reported to be greater than TBT at Stations 6 and 7 when this same procedure was followed (Table IV). Highest concentrations of TBT were reported at both Station 1 (1801 ng L - l TBT in Port Annapolis Marina) and Station 3 (1171 ng L - 1 TBT in Mears Marina) during early June (Table III). Significant reductions in TBT concentrations occurred during late summer and early fall in both of these marina areas. The lowest TBT concentrations reported in Stations 1 and 3 were 109 and 77 ng L - 1 , respectively (Table III). The highest concentration of TBT reported in the Back Creek Stations (2, 4, 5, and 6) was 807 ng L - 1 at Station 2. This peak concentration was reported during early June. TBT concentrations less than 66 ng L - 1 were reported in September at

DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT

I

7

6

5

4

3

2

Sn species (ng L - ' )

Station

666 1801 398 807 477 1171 170 341 165 368 16 12 5 5

6/3/86 486 415 410 344 301 236 418 359 334 227 337 283 39 26

6/16/86 122 120 123 116 98 109 66 79 73 60 36 27 31 17

6/30/86 223 138 172 198 173 611 145 83 156 130 88 70 35 26

7/14/86 273 659 225 149 169 116 190 167 161 128 48 30 43 27

7/28/86

Date

194 171 151 138 105 109 120 98 93 92 39 28 12 9

8/12/86 100 360 65 96 90 100 80 76 55 45 66 103 28 28

8/26/86

93 109 81 88 62 77 63 89 67 77 111 110 48 48

9/9/86

101 147 57 65 82 92 92 93 77 63 27 25 23 16

9/22/86

DBT and TBT (ng L - i ) reported bi-weekly at the 7 stations for a 4 month period. A mean of two replicates was reported. TTBT was not detected

TABLE III

o c z

"0

9

Z

G >

,-q m

> ~, r" z~ ~7

236

LENWOOD

W. HALL,

Jr. ET AL

TABLE IV Analysis of DBT and TBT ( ng L 1) by station averaging across dates for the bi-weekly sampling Station

Sn N Species ( ng L ~)

Mean

Std Dev

Minimum value

Maximum value

Std error of mean

Sum

1

DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT

251 435 187 222 173 291 149 154 131 132 85 76 29 22

210 611 151 266 143 466 111 126 93 105 107 88 14 14

73 103 47 56 57 66 53 61 49 41 8 0 0 5

862 2664 601 1124 631 1859 496 525 439 376 468 342 52 50

50 144 36 63 34 110 26 30 22 25 25 21 3 3

4512 44236 7835 372555 3361 22821 3999 20571 3113 20587 5239 217434 2683 12402 2765 15825 2357 8711 2375 11100 1533 11344 1372 7821 526 198 397 193

2 3 4 5 6 7

18 18 18 18 18 18 18 18 18 18 18 18 18 18

Var.

C.V.

84 140 81 120 83 160 75 82 71 80 125 116 48 63

TABLE V Two-way Factorial Analysis of Variance (ANOVA) of TBT (ng L ~) to test for station and date effects during the bi-weekly sampling. The non-detectable values were set equal to 0 Source

DF

General Linear Models Procedure Sum of Squares

Mean Square

F Value

PR>F

R-Square

C.V.

3.02

0.0001 Root MSE 236

0.75

124 TBT Mean 190

Model Error Corrected Total

62 63 125

10426508 3510934 13937442

168169 55729

Source

DF

Type SS

F Value

PR>F

DF

6

2110548

6.3

0.0001

6

3718148

8.3

0.0001

48

4597813

1.7

0.022

Type III SS

F Value

6

2110548

6.3

8

3718148

8.3

48

4597813

1.7

PR > F a

Station 0.0001 Date 0.0001 Station • Date 0.0220

Tests of hypothesis using the Type III MS for Station x Date as an error term Source

DF

Type III SS

F Value

PR>F

Station Date

6 8

2110548 3718148

3.7 4.9

0.0044 0.0002

a P R > F less than 0.05 indicates a significant effect.

SPATIAL

AND TEMPORAL

DISTRIBUTION

OF BUTYLTIN

COMPOUNDS

237

TABLE VI Duncan's Multiple Range Test of TBT (ng L ~) was used to test for station and date effects during the bi-weekly sampling. The MES term in Table Ill was used in this test. Means with the same letters are not significantly different. Station Effects N

Mean TBT (ng L -j)

Duncan Grouping

18 18 18 18 18 18 18

435 291 222 154 132 76 22

A A B B C B C D B C D C D D

14 14 14 14 14 14 14 14 14

643 270 182 179 115 92 85 75 71

A

Station 1 3 2 4 5 6 7 Date 6/3/86 6/16/86 6/30/86 7/14/86 7/28/86 8/12/86 8/26/86 9/9/86 9/22/86

B B B B B B B B

S t a t i o n 2. T h e highest c o n c e n t r a t i o n s o f T B T r e p o r t e d at S t a t i o n s 4, 5, a n d 6 (283-368 ng L - 1) were r e p o r t e d in June; lower values were r e p o r t e d d u r i n g the later s a m p l i n g dates. T h e highest c o n c e n t r a t i o n o f T B T r e p o r t e d at S t a t i o n 6 was 283 ng L - I . T h e highest c o n c e n t r a t i o n o f T B T r e p o r t e d at S t a t i o n 7 (Severn River) was 48 ng L - 1 d u r i n g the 9 / 9 / 8 6 s a m p l e p e r i o d . T h e lowest T B T value (5 ng L - 1 ) at S t a t i o n 7 was r e p o r t e d d u r i n g early J u n e (Table III). A t w o - w a y f a c t o r i a l A N O V A a n d D u n c a n ' s M u l t i p l e R a n g e Test was used to assess s t a t i o n , d a t e a n d s t a t i o n d a t e i n t e r a c t i o n effects on T B T c o n c e n t r a t i o n s (Tables V a n d VI). S t a t i o n , d a t e a n d their i n t e r a c t i o n was significant ( T a b l e V). B o t h m a r i n a S t a t i o n s (1 a n d 3) h a d the highest m e a n c o n c e n t r a t i o n s o f T B T (Table VI). H i g h e s t m e a n T B T c o n c e n t r a t i o n s o c c u r r e d d u r i n g the 6 / 3 / 8 6 s a m p l i n g p e r i o d ( T a b l e VI). DAILY SAMPLING D B T a n d T B T c o n c e n t r a t i o n s r e p o r t e d at S t a t i o n l , 4 a n d 7 d u r i n g the 5-day s t u d y are p r e s e n t e d in T a b l e V I I . T T B T was n o t detected at a n y o f the Stations. H i g h e s t D B T c o n c e n t r a t i o n s at S t a t i o n 1 (346 ng L - 1), S t a t i o n 4 (211 ng L - 1) a n d S t a t i o n 7

238

LENWOOD W. HALL, Jr. ET AL T A B L E VII DBT and TBT (ng L ~) reported at Stations 1,4, and 7 during the 5-day study. A mean of two replicates was reported. T T B T was not detected Day

Date

Thursday

8/7/86

Friday

8/8/86

Saturday

8/9/86

Sunday

8/10/86

Monday

8/11/86

Sn species (ng L 1)

DBT TBT DBT TBT DBT TBT DBT TBT DBT TBT

Station 1

4

7

346 525 317 352 220 293 206 497 184 316

193 149 211 165 120 113 127 144 115 119

30 26 44 45 30 33 12 14 11 10

T A B L E Vlll Two-way Factorial A N O V A and Duncan's Multiple Range Test of TBT (ng L - ~) was used to test for station and date effects during the daily sampling. Means with the same letter are not significantly different. The non-detectable values were set equal to 0 Source

ANOVA Sum-of-squares

DF

Mean-square

F-ratio

P

Date Station Date • station Error

37425 724346 59155 48468

4 2 8 15

9356 362173 7394 3231

2.9 112 2.3

0.058 0.000 0.079

Station effects

Duncans multiple range test

Station

Mean TBT

Duncan grouping

1 4 7

396 138 25

A B C

Date

Mean TBT

Duncan grouping

Thursday Sunday Friday Monday Saturday

233 218 186 148 146

A A A

Date effects

B B B B

SPATIAL AND TEMPORAL DISTRIBUTION OF BUTYLTIN COMPOUNDS

239

(44 ng L - I ) were reported on Thursday, Friday and Friday, respectively. The greatest change in DBT occurred at Station 7 as the highest value was 4 times greater than the lowest value. A two-way factorial ANOVA and Duncan's Multiple Range Test demonstrated that station significantly affected TBT distribution; however, date and the date*station interaction was not significant (Table VIII). TBT concenctrations were greatest at Station 1 followed by Stations 4 and 7, respectively (Table VIII). The highest TBT concentrations at Station 1 (525 ng L - 1), Station 4 (165 ng L - l) and Station 7 (45 ng L - 1 ) were reported on Thursday, Friday and Friday, respectively (Table VII). The greatest change in TBT occurred at Station 7. The highest TBT concentration (45 ng L - J) was 4.5 times greater than the lowest value (10 ng L - 1). The maximum TBT concentrations at both Stations 1 and 4 were - 1.8 and - 1.5 times greater than the lowest concentrations. TIDAL SAMPLING

DBT and TBT concentrations reported during the tidal experiments are presented in Table IX. TTBT was not detected at any of the stations during these experiments. DBT concentrations were highest at the 1400, 1600 and 1800h time intervals when all stations were combined. DBT was greatest in Port Annapolis Marina (Station 1) followed by Station 4 (Back Creek) and Station 7 (Severn River), respectively. A two-way factorial ANOVA and Duncan's Multiple Range Test was used to assess station, time, (tidal effects) and their interaction on TBT distribution (Table X). Station, time and their interaction was found to be significant. Mean TBT concentrations were significantly highest at Station 1 followed by Stations 4 and 7, respectively. Mean TBT values were reported to be greatest at the 1400 and 1600 time interval when TBT means were averaged over stations. The highest TBT concentrations reported at Station 1 (770 ng L - 1 ) , Station 4 (184 ng L -1) and Station 7 (22 ng L -1) occurred at 1400, 1400, and 1800 hr,

TABLE IX DBT and TBT (ng L ~) reported at Stations 1, 4 and 7 during the tidal study. TTBT was not detected. High tide was at approximately 0430 and 1645 hr. Low tide was at 1100 hr. A mean of two replicates was reported Station

1 4 7

Sn species (ng L ~)

DBT TBT DBT TBT DBT TBT

Time period 0600

0800

1000

1200

1400

1600

1800

163 164 117 119