Introduction

Lake Ontario is one of the world’s largest lakes with a surface area of 19,000 km2 and an average depth of 86 m. In addition to supporting valuable commercial and recreational fisheries, it is the major source of drinking water to surrounding US and Canadian metropolitan areas1. Canadian researchers recently reported that polybrominated diphenyl ethers (PBDEs) are rapidly increasing in Lake Ontario fish tissue since the early 1980s2. PBDEs have been widely used in manufacturing as an additive flame retardant3. We analyzed extracts of large volume surface water samples collected on Lake Ontario in the Fall of 1999 to establish baseline information on Lake Ontario surface water PBDE concentrations, dominant congeners and distribution between suspended solids and dissolved phases. This is the first report of PBDEs being measured in North American surface waters.

Sampling Methodology

Large volume surface water samples were collected during fall isothermal conditions with the assistance of U.S. EPA’s research vessel the Lake Guardian (Fig. 3). Lake water was pumped into the samplers using an intake tube suspended from a boom off the side of the vessel and towed 1 m below the surface (Figs. 4 & 5) Duplicate samples were collected in the eastern, central and western basins of the lake (Fig. 6). Samples were collected over 24 hrs while covering an ~50 km2 grid pattern to collect a spatially and temporally integrated sample. Surface water was pumped through a glass fiber filter cartridge (1 µm nominal porosity) to capture contaminants bound to suspended solids and then through two columns each holding 35 g of XAD resin (divinylbenzene-styrene copolymer) to capture dissolved hydrophobic contaminants (Figs. 7, Table 1).

Fig. 3 Research Vessel Lake Guardian U.S. EPA Great Lakes National Program

Fig. 4 Water intake tube attached to streamlined steel weight.

Fig. 5 Towing water intake off the side of the vessel.

Analytical Methods

Filter samples and XAD resins were spiked with a suite of 13C labeled internal standards, soxhlet extracted overnight with dichloromethane, and the extract fractionated on a Florisil™ column. The Florisil column fraction containing ortho-substituted PCBs was concentrated down to 20 µL and analyzed for PBDEs using a pressure programmed DB-5HT column and detected by EI positive ion HRMS at 10,000 mass resolution, in selected ion mode, monitoring two peaks in the molecular ion cluster. The method was calibrated with a set of 41 PBDE congeners (mono to decabromo, based on Cambridge Isotope Labs analytical standard #EO-4980). PBDEs were quantitated against 13C labeled internal standards and individual response factors were determined for each reported congener.

Results

Concentrations of PBDEs in Lake Ontario surface waters are ~ 6 pg/L with ~80% in the dissolved phase (Fig. 9). Duplicate samples showed good agreement. BDE-47 and BDE-99 are the most abundant congeners together making up ~60% of total PBDEs (Fig. 10).

0

0.5

1

1.5

2

2.5

3

17 25 28 47 99 100 153 154Most Abundant PBDE Congeners

pg/L

West-A

West-B

Central

East-A

East-B

Fig. 10 Total (dissolved + solids) concentrations of most abundant PBDE congeners detected in Lake Ontario surface waters (pg/L), Fall 1999.

Fig. 9 Lake Ontario surface water dissolved and suspended solids PBDES concentrations (pg/L) collected Fall 1999.

Comparison of the mass of PBDEs found on the first and second XAD columns show that the first column captured most (>90%) of the total dissolved phase PBDEs. BDE-47 and BDE-99 were not detected on the second columns (Fig. 11).

0

100

200

300

400

500

600

700

800

7 8 15 17 25 28 47 49 66 77 85 99 100 153 154 155 207

PBDE Congener IUPAC ID

pic

og

ram

s

First XAD

Second XAD

Fig. 11 Mass of dissolved PBDE congeners captured on the first and second XAD resin columns, Western Basin.

Reported surface water PBDE concentrations were corrected for lab contamination by subtracting procedural blank concentrations on a batch specific basis. Three of the four batches of samples were analyzed in a newly constructed lab. Procedural blanks from the new lab showed ~ 5 to 10 times higher PBDE concentrations than blanks from the older lab (Figs 12 & 13). It was determined that the lining of the ventilation ducts in the new lab (Lab #2) contained percent levels of PBDEs. The absence of BDE-47 and BDE-99 on the second XAD column, analyzed separately from the first, provides good evidence that reported PBDE surface water concentrations are not simply the result of lab contamination.

0

2000

4000

6000

8000

10000

Lab #1 Lab #2 -A Lab #2 -B Lab #2 -C

pg

/ s

am

ple

0

500

1000

1500

2000

2500

3000

47 99 100 154 209

PBDE Congener IUPAC ID

pg

/sa

mp

le

Lab #1

Lab #2 - A

Lab #2 - B

Lab #2 - C

Fig. 12 Total PBDE (pg/sample) detected in procedural Blanks.

Fig. 13 Dominant PBDE congeners Procedural Blanks.

Discussion

BDE-47 and BDE-99 are the dominant PBDE congeners in Lake Ontario surface waters accounting for more than 60% of total PBDEs. These are also reported to be the dominant congeners in Lake Ontario lake trout tissue2.

The finding that ~80% of PBDEs are in the dissolved phase is surprising but may be partly a consequence of the low total suspended solids concentrations present in Lake Ontario surface water (<1 to 2 mg/l). Most of the mass of PCBs in Lake Ontario surface water are also found in the dissolved phase.

The absence of BDE-47 and BDE-99 on second XAD columns indicates that all of these congeners were captured by the first XAD column. XAD would appear to be an effective extraction media for these two congeners of interest.

The presence of percent levels of PBDE in analytical lab air duct-work points out the need for careful consideration of the chemical composition of all lab building materials when doing low level detection work (pg) for PBDEs.

Conclusions

• Total PBDEs are ~ 4 to 6 pg/L in open waters;

• PBDE congeners tetra-47BDE & penta-99BDE make up ~60% of total;• > 80% of PBDEs are in the dissolved phase;

• Similar PBDE concentrations and congener distribution across the Lake.

• Parts per quadrillion concentrations of PBDE can be quantified in surface waters using large volume sampling techniques.

AcknowledgementsFunding and logistical support was provided by U.S. EPA’sGreat Lakes National Program (Chicago Office) and EPA Region 2 (New York Office). Thanks also to the staff at Axys Analytical

Special thanks to the Captain and Crew of the R/V Lake Guardianwho made this project possible.

References1 Flint, R.W.; Stevens, R.J.J., State University of New York at Buffalo, 1989, Great Lakes Monograph No. 2.2.Luross J.M., Alaee M., Sergeant D., Whittle M., and Solomon K., 2000. Spatial and Temporal Distribution of Polybrominated Diphenyl Ethers in Lake Trout from the Great Lakes. Presented at the 2nd Annual Workshop on Brominated Flame Retardants in the Environment, Burlington, Ontario, June 5-6, 2000. 3 De Boer, J.; de Boer, K.; Boon, J.P., Handbook of Env. Chemistry, 2000, 3, Part K, 61-95.4 Junk, G. A.; Richard, J.J.; Grieser, M.D.; Witiak, J.L.; Arguello, M.D.; Vick, R.; Svec, H.J.; Fritz, J.S.; Calder, G.V., J. of Chromatography, 1974, 99, 745-762. 5 Swackhammer, D.L.; Armstrong, D.E., J. Great Lakes Res., 1987, 13, 24-36.6 Litten, S.; Donlon, J., Enhanced toxics sampling for trace organics in Lake Ontario. 1998. New York State Department of Environmental Conservation, Bureau of Watershed Assessment and Research, Division of Water, 50 Wolf Rd., Albany, NY.

Fig. 1 Lake Ontario is the last in the chain of the Great Lakes receiving approximately 90% of its inflow from upstream lakes..

Fig. 2 PBDE trends observed in Lake Ontario lake trout tissue (adapted from Luross et al. 2000).

~I meter deep

Lake

XAD Resin #2

Capture suspended solids

Capture “break through” compounds from first XAD column.

Nytex Netting

XAD Resin #1

Glass Fiber Filter

Surface Water Intake

Filter out plankton & debris

Capture dissolved contaminants

Flow MeterFlow Meter

Flow MeterFlow Meter

Overflow to Lake

Fig. 7 Schematic of Large Volume Sampler

XAD columns were placed in series to increase the total volume of resin available to capture dissolved contaminants. The extraction efficiency of the first XAD column can be evaluated by analyzing the columns separately. Ideally, no hydrophobic contaminants should be found on the second column. One advantage of large volume sampling is that any detection limit can be achieved provided a large enough sample volume is processed. XAD has been a tool for concentration of environmental contaminants in water for over 25 years4,5.

Western Western

sampling areasampling area

Eastern Eastern sampling areasampling areaCentralCentral

sampling areasampling area

LakeLake OntarioOntario

Province of OntarioProvince of Ontario

New York StateNew York State

Fig. 6 Fall 1999 Lake Ontario surface water sampling locations.

Table 1. Sample volumes (Liters) processed for XAD Table 1. Sample volumes (Liters) processed for XAD (dissolved phase) and filter (suspended solids) samples(dissolved phase) and filter (suspended solids) samples..

XAD Filters

Litres Litres

Western Basin Sampler#1 404.4 4271.0Sampler#2 867.7 5037.0

Central Basin Sampler#1 431.4 4562.8Sampler#2 845.2 5521.5

Eastern Basin Sampler#1 349.1 4337.3Sampler#2 729.1 4780.9

XAD columns

Filter cartridge, glass fiber

Fig 8. Large volume sampler

0 1 2 3 4 5 6 7

Western Basin - B

Western Basin - A

Central Basin

Eastern Basin - B

Eastern Basin - A

pg/L

SuspendedSolidsDissolved

ng

/g L

ipid

0

200

400

600

800

1000

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

Frederick Luckey, New York State Frederick Luckey, New York State DECDECSimon Litten, New York State DECSimon Litten, New York State DEC

Establishing Baseline Levels of PBDEs in Lake Ontario Surface WaterEstablishing Baseline Levels of PBDEs in Lake Ontario Surface Water

Brian Fowler, AXYS Analytical ServicesBrian Fowler, AXYS Analytical Services