Influence of Baltimore's Urban Atmosphere on ...

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Influence of Baltimore's Urban Atmosphere on Organic Contaminants over the Northern Chesapeake Bay John H. Offenberg & Joel E. Baker To cite this article: John H. Offenberg & Joel E. Baker (1999) Influence of Baltimore's Urban Atmosphere on Organic Contaminants over the Northern Chesapeake Bay, Journal of the Air & Waste Management Association, 49:8, 959-965, DOI: 10.1080/10473289.1999.10463864 To link to this article: http://dx.doi.org/10.1080/10473289.1999.10463864

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TECHNICAL PAPER

Offenberg and 49:959-965 Baker ISSN 1047-3289 J. Air & Waste Manage. Assoc. Copyright 1999 Air & Waste Management Association

Influence of Baltimore’s Urban Atmosphere on Organic Contaminants over the Northern Chesapeake Bay John H. Offenberg Chesapeake Biological Laboratory, University of Maryland, Solomons, Maryland, and Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland

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Joel E. Baker Chesapeake Biological Laboratory, University of Maryland, Solomons, Maryland

ABSTRACT Air and precipitation samples were collected along an urban to over-water to rural transect across the northern Chesapeake Bay as a preliminary investigation into the spatial extent of elevated atmospheric concentrations of urban-derived persistent organic pollutants. Air samples were collected daily from June 3–9, 1996, along the transect as part of the Atmospheric Exchange over Lakes and Oceans project. Total (gas + particle bound) atmospheric polycyclic aromatic hydrocarbon concentrations [Σ-PAH] ranged from 0.4 to 114 ng/m3, and gas phase polychlorinated biphenyl concentrations [Σ-PCB] ranged from 0.02 to 3.4 ng/ m3. Strong concentration gradients were found for both PAHs and PCBs, with the highest concentrations in the city and the lowest at the downwind rural site. Gas and particle bound PAHs varied independently in the city, possibly due to strong but geographically separated emission sources. A precipitation event collected during westerly

IMPLICATIONS Persistent organic contaminants such as polycyclic aromatic hydrocarbon concentrations and polychlorinated biphenyl concentrations can enter surface waters via atmospheric (wet and dry) deposition and bio-accumulate in aquatic organisms. The geographic extent and relative enrichment over background concentrations of these contaminants in the urban atmosphere may play a significant role in the total delivery of these contaminants to lakes and estuaries, especially those adjacent to urban areas. The results of this preliminary field campaign demonstrate that concentrations in Baltimore, MD, are elevated relative to background concentrations. Additionally, atmospheric deposition to the adjacent water body is increased relative to regional background levels in a region that extends downwind of the city. Thus, emissions to the atmosphere above this urban area are contributing elevated contaminant loadings to the adjacent surface water body.

Volume 49 August 1999

winds contained fourfold higher Σ-PAH and twelvefold higher Σ-PCB concentrations at the over-water site than at the rural background location, further indicating that the urban plume extends from Baltimore, MD, over the northern Chesapeake Bay over a spatial scale of approximately 30 km. INTRODUCTION Atmospheric deposition to the water surface is an important and often dominant source of persistent organic contaminants to remote aquatic systems waters.1–6 Urban atmospheres often contain extremely elevated contaminant concentrations, which may enhance deposition fluxes to adjacent surface waters through wet and dry deposition, and through enhanced gas exchange.7–14 Much of the recent research on the elevated deposition of urban atmospheric contaminants has been performed in and around Chicago, IL/Gary, IN, due to the extremely high concentrations and the apparent influence on adjacent Lake Michigan. Limited fieldwork has been performed around other urban centers, and the translation of the findings in the heavily contaminated Chicago area to other industrialized areas has been uncertain. Greater Baltimore is heavily developed, with more than 2.3 million people living within the 7,120-square kilometer metropolitan area. The Interstate 95 corridor runs northeast from Washington, DC, through downtown Baltimore and continues on to Philadelphia, PA, and points north. Much of the heavy industry in the Baltimore area lies along the Patapsco River, which flows east to the Chesapeake Bay approximately 15 km from downtown Baltimore’s Inner Harbor. A municipal wastewater treatment facility, a landfill, two coal-fired electric power generation plants, a large steel mill, a military munitions depot, and multiple ship repair yards and petroleum storage facilities lie to the east of downtown Baltimore. Neighboring this urban area, the Chesapeake Bay is a shallow estuary (7 m average depth) Journal of the Air & Waste Management Association 959


Offenberg and Baker particularly susceptible to the influence of atmospheric deposition, due to a large surface areato-volume ratio.15 The Atmospheric Exchange over Lakes and Oceans (AEOLOS) project is a multi-institutional effort to quantify the enhanced deposition of atmospheric pollutants to adjacent waters. Phase I of AEOLOS centered on three sampling campaigns in Chicago and over southern Lake Michigan.7–9,16–20 Phase II extends this study to the coastal waters, with intensive studies in the northern Chesapeake Bay downwind of the Baltimore metropolitan area. This paper presents initial results from AEOLOS phase II to provide the first measurements of organic contaminant gradients in this urban coastal water region. Other reports will describe ambient particle size distributions of aerosol-bound contaminants, enhanced dry and wet deposition, air/water gas exchange,14 and source attribution of contaminants over the northern Chesapeake Bay.

Hart-Miller Island

MATERIALS AND METHODS Air and precipitation samples were collected along a transect from Baltimore across the northern reaches of the estuary (see Figure 1). Simultaneous eight-hour, high-volume air samples were collected daily beginning at 8 am EST at Fort McHenry National Monument Figure 1. Air and precipitation sampling locations in Baltimore, MD, and across the and Historic Shrine in Baltimore, on Hartnorthern Chesapeake Bay. Miller Island (18 km northeast of Ft. McHenry), and at U.S.C.G. Station Stillpond (23 km further northeast) along the eastern shore of from the authors. Meteorological data was collected by the bay. Samples were collected for seven consecutive the Maryland Department of Transportation, Key Bridge 3 days beginning June 3, 1996. Approximately 400 m of Authority by instruments mounted on the Francis Scott Key Bridge, located near the mouth of the Patapsco air was filtered sequentially through two glass fiber filRiver. Values were recorded by continuous chart reters (GFF), then passed over a polyurethane foam (PUF) corder, and averages for each sampling period were calplug to trap gas phase contaminants. After collection, culated (see Table 1). all PUF and filter samples were individually sealed, immediately frozen, and kept in the dark at -20 °C until analysis. Concentrations of 39 individual polycyclic aroTable 1. Meteorological conditions during sampling periods as measured by the matic hydrocarbons (PAHs) and 71 polychlorinated biKey Bridge Authority at Francis Scott Key Bridge. phenyl congeners (PCBs) were quantified by GC/MS and Wind Speed Wind Direction Temperature GC/ECD, respectively, after a Florisil cleanup.21 The lone Date (m/sec) (degrees) (°C) rain event during the week (night of June 4, 1996) was collected with multiple automated 1 m2 samplers, 22 6/3/96 3.0 44 17.5 which filter the water through a GFF and then collect 6/4/96 3.8 142 19.5 the operationally defined dissolved phase on a column 6/5/96 3.2 278 21.2 of XAD-2 resin. Subsequently, the rain samples were pro6/6/96 5.1 130 22.2 cessed and quantified with similar methods used for air 6/7/96 4.8 154 22.0 samples.9 The Σ-PCB and Σ-PAH concentrations are pre6/8/96 4.6 154 25.2 sented and discussed here, although congener-specific 6/9/96 5.0 149 24.0 PCB and individual PAH concentrations are available 960 Journal of the Air & Waste Management Association



Offenberg and Baker Quality Assurance Recoveries of analytical surrogates spiked into each sample prior to analysis averaged 65% ± 25%, 540% ± 1,150%, 86% ± 22%, 87% ± 24%, 1,220% ± 660%, 65% ± 18%, and 60% ± 15% (avg. ± std. dev.; d8-napthalene, d10-fluorene, d10-fluoranthene, d12-pyrene, and PCB Nos. 14, 65, and 166). The high recoveries for d10-fluorene and PCB No. 14 were due to co-eluting unidentified chromatographic interferences. There were no systematic differences in surrogate recovery between the three locations or between sample matrices. The uniform recoveries indicated that no correction for laboratory biases was necessary. Furthermore, field and procedural PUF, GFF, rain resin, and rain filter blanks were processed concurrently with field samples to quantify operational, matrix-specific detection limits. PCB congener- and PAH compound-specific limits of detection were established for all matrices as three times the average mass of analyte measured in procedural field blanks. Calculation of LODs for air samples resulted in detection limits of approximately 0.70 and 0.02 ng/m3 for ΣPAHs (PUF and filter, respectively) and 0.05 ng/m3 for vapor Σ-PCBs. Rain LODs were 5.4 and 4.6 ng/L for Σ-PAHs and 0.6 and 0.7 ng/L for Σ-PCBs (resin and filter, respectively). After calculating limits of detection, samples were blank-filtered. Congeners and individual compounds, which were not greater than the matrix-specific, blankbased limits of detection, are not reported in the following results. Therefore, all sample concentrations reported herein exceed three times the respective field blank levels. Analyte breakthrough on the PUF sorbent was determined by analysis of three split PUFs collected at the urban site, where the atmospheric concentrations were expected to be the highest, and breakthrough most likely to occur. Percent breakthrough averaged 7% for vapor trichloro-PCBs and 5% for vapor phenanthrene, the two worst cases of breakthrough observed. Vapor adsorption to GFFs was examined at the urban site, where the artifact was expected to be worst. Sorption to the filter was a

minor contribution to the total measured particle-bound concentration for PAHs. For example, the contribution by the backup filter to the total particle-bound concentration averaged 10% for phenanthrene and 6% for fluoranthene. Due to the consistently low breakthrough on the PUF and low vapor adsorption to the GFFs, no correction was made to the concentrations measured in either phase. RESULTS AND DISCUSSION During the week of July 3, 1996, gas phase Σ-PCB concentrations measured at all three locations ranged from 0.02 to 3.36 ng/m3, while the concentrations at the urban site ranged from 0.68 to 0.36 ng/m3 (see Table 2). These concentrations lie between the range of those found over the rural Chesapeake Bay in 1991, 0.02 to 0.51 ng/m3,22 and those typically found in highly contaminated urban atmospheres, such as Chicago, for which Simcik et al.7 report a range of 0.27 to 14 ng/m3 during 1994–1995, and for which Cotham and Bidleman23 report a similar range of 0.32 to 9.9 ng/m3 during 1988. The concentrations found in downtown Baltimore are similar in magnitude to those found during 1993 in Bloomington, IN, which ranged from 0.65 to 2.5 ng/m3 ,24 and to those found over southern Green Bay, Lake Michigan in 1989 (0.67 to 2.20 ng/m3).25 The gas phase PCB concentrations measured in Baltimore and over the Chesapeake Bay were dominated by triand tetra-chlorinated congeners (see Figure 2). Over-water Σ-PCB concentrations ranged from 0.21 to 0.74 ng/m3 and were of a similar range as those measured by Simcik et al.7 over southern Lake Michigan (0.14 to 1.1 ng/m3). Similarly, the gas concentrations measured at the downwind site (0.02 to 0.38 ng/m3) were similar to other middle latitude continental background concentrations, being the same magnitude as those measured during 1990–1992 at rural locations across the Great Lakes (0.09 to 0.36 ng/m3);26 those measured adjacent to Lake Baikal, Russia, during 1991 (0.113 to 0.266 ng/m3);27 and those measured at Bermuda

Table 2. Summary of air concentrations at urban, over-water, and rural sites across the northern Chesapeake Bay. Urban

Date 6/3/96 6/4/96 6/5/96 6/6/96 6/7/96 6/8/96 6/9/98

Σ-PCB ng/m3 Gas 0.68 1.64 0.38 0.81 2.17 1.09 3.36


Over-Water Σ-PAH ng/m3 Gas Part.

39.18 21.32 112.78 31.57 28.64 30.13 17.37

7.83 1.41 1.58 0.88 9.72 1.16 2.16

Σ-PCB ng/m3 Gas 0.21 0.53 0.74 0.73 0.35 0.74 0.59

Rural

Σ-PAH ng/m3 Gas Part. 3.54 3.68 13.82 3.98 2.86 5.74 4.00

1.58 0.67 2.42 0.30 0.23 0.33 0.35

Σ-PCB ng/m3 Gas 0.24 0.02 0.29 NQ 0.30 0.34 0.18

Σ-PAH ng/m3 Gas Part. 5.66 0.41 3.53 NQ 4.17 4.12 3.51

0.70 0.31 0.36 0.35 0.24 0.15 0.49

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Offenberg and Baker

Figure 2. Average gas phase PCB homologue distributions in air at urban, over-water, and rural locations across the northern Chesapeake Bay in ng/m3. Note differences in scales.

in 1992–1993 (avg. 0.38 ng/m3).28 Additionally, the concentrations measured at the rural site approximately 40 km northeast of downtown Baltimore (0.34 to 0.02 ng/ m3) agree well with those measured during 1990–1991 at Elms, MD, a rural site adjacent to the central Chesapeake Bay, where vapor phase Σ-PCB averaged 0.21 ng/ m3 (± 56 % relative standard deviation).21 Total (gas + particulate) Σ-PAH concentrations measured at all three sites ranged from 0.4 to 114 ng/m3. Gas phase concentrations are dominated by phenanthrene, while the particle-bound phase concentrations are dominated by fluoranthene and pyrene (see Figure 3). Gas phase Σ-PAH concentrations range from 17 to 113 ng/ m3, accounting for ~90% of the atmospheric PAH burden in Baltimore. Over-water gas phase concentrations range from 2.9 to 13.8 ng/m3 and constitute ~87% of the total measured at Hart-Miller Island. Rural gas phase ΣPAH concentrations range from 0.4 to 5.7 ng/m3, comprising 89% of the total Σ-PAH observed at Stillpond, MD. For comparison, Simcik et al.7 report vapor Σ-PAH concentrations that range from 27 to 430 ng/m3 in Chicago in 1994–1995, 0.8 to 70 ng/m3 over southern Lake Michigan and 4.1 to 55.1 ng/m3 downwind at a rural location. For further comparison, Pirrone et al.11 report an average of 150 ± 103 ng/m3 at the same site in Chicago and 15.4 ± 12.5 ng/m3 over-water in 1993, and Cotham and 962 Journal of the Air & Waste Management Association

Bidleman23 report a range of 75 to 1,410 ng/m3 at another site in Chicago during 1988. Similar to the Σ-PCB concentrations, over-water and rural total Σ-PAH concentrations measured here are of comparable magnitude to those measured over southern Lake Michigan and in South Haven, MI (0.8 to 70 ng/m3 and 4.1 to 56.1 ng/ m3, over-water and rural).7 Like PCBs, PAH concentrations at the rural site were comparable to concentrations measured adjacent to the central Chesapeake Bay (average 2.7 ng/m3).22 Atmospheric concentrations of PAHs and PCBs depend on wind direction at both the urban and over-water sites yet show no apparent correlation with wind direction at the rural site (see Figure 4). Gas phase PCBs appear to have a strong emission source in the heavily industrialized sections of greater Baltimore along the south shore of the Patapsco River. During southeasterly winds, Σ-PCB concentrations measured at the downtown site were the highest measured in this study (3.4 ng/m3), and the one day of westerly winds exhibited the lowest concentrations at the urban site (0.32 ng/m3). During this westerly wind, concentrations were the lowest urban Σ-PCB concentrations measured and were fourfold lower downtown relative to all other times, while concentrations were not significantly different at the over-water or rural sites relative to other wind directions.

Figure 3. Average total (gas particle bound) concentrations of individual PAHs in air at urban, over-water, and rural locations across the northern Chesapeake Bay in ng/m3. Note differences in scales. Volume 49 August 1999


Offenberg and Baker 0.6 to 2.4 ng/m3 during westerly winds. Concentrations of fluoranthene, the dominant particle-bound PAH, were highest at the urban site during southeasterly winds (see Hart-Miller Island Figure 6), reaching a concentration of 0.92 ng/m3, more than three times greater than the other urban samples (average 0.28 ng/m3). However, of the five samples, which were collected at the urban site during southeasterly winds (~115 to ~155 degrees), only one has elevated particlebound PAH concentrations (Friday, June 7, 1996). This may result from sampling of a strong local source due to small shifts in wind direction not adequately detected by the meteorological data collected. The differences between particle-bound and gas phase PAH concentration dependence on wind direction is likely a result of gas and particle sources, which are geographically separate, with the region west of downtown as a source of gas phase PAHs and the heavily industrialized area east of the city releasing mostly particle-bound PAHs to the atmosphere. Additionally, the highest particle-bound Σ-PAH concenFigure 4. Gas phase Σ-PCB concentrations versus wind direction plot for urban, trations were measured at the downtown site during over-water, and rural locations across the northern Chesapeake Bay in ng/m3. southeasterly winds blowing from the industrialized Length of bar indicates concentrations and orientation indicates direction from areas (9.7 ng/m3), while simultaneously, gas phase Σwhich wind blew during the sampling period. PAH concentration of 28.6 ng/m3 was below the average for all urban samples collected (40.1 ng/m3). During Consistent with the dynamics of gas phase PCBs, southeasterly winds, both particle-bound and gas phase PAH concentrations also depend on wind direction. ToΣ-PAH concentrations at the over-water site were not sigtal Σ-PAH concentrations were fourfold higher downtown nificantly different from those measured at the rural during westerly winds blowing from the residential/urbackground site. banized areas of the city, when compared with those meaPrecipitation was collected at the over-water and rusured during southeasterly winds blowing from the inral sites during the lone rain event of the week. Rain dustrialized areas. This increase in concentration extended out over the northern Chesapeake Bay as a three-and-one-half-fold increase in total Σ-PAH concentration at the over-water location observed during westerly wind relaHart-Miller Island tive to all other wind directions. These ΣPAH increases resulted from higher gas phase concentrations, which were measured during the one day of westerly winds than during any other period at the urban site. For example, phenanthrene, the dominant gas phase PAH, decreased from a high of 63.2 ng/m3 under westerly winds to an average of 13.4 ng/m3 during periods of non-westerly winds (see Figure 5). This fivefold increase during westerly wind suggests a strong emission source located west of the urban sampling site, with a likely locus over the urban center of Baltimore. While the total Σ-PAH increased during Figure 5. Gas phase phenanthrene concentrations versus wind direction plot for urban, westerly wind, particle bound Σ-PAHs decreased over-water, and rural locations across the northern Chesapeake Bay in ng/m3. Length of from 3.9 to 1.6 ng/m3 at the downtown locabar indicates concentrations and orientation indicates direction from which wind blew during the sampling period. tion and increased at the over-water site from Volume 49 August 1999


Offenberg and Baker Baltimore is similar to the decrease downwind of Chicago, although the geographic extent of the two urban plumes may differ. Thus, through analogy to Chicago rain and air concentrations, Σ-PCB concentrations in precipitation in Baltimore could be expected to be higher still than those measured over-water at Hart-Miller Island (5.0 ng/L), though not likely as high as those measured in Chicago (29.3 ± 24.0 ng/L). Elevated levels of urban atmospheric contaminants measured in both air and precipitation extend approximately 30 km downwind of the greater Baltimore urban area. This geographical extent of the urban plume is supported by elevated concentrations 20 km downwind of the urban center, coupled with the decline to background concentrations 40 km downwind of downtown Baltimore.


Hart-Miller Island

Figure 6. Particle-bound fluoranthene concentrations versus wind direction plot for urban, over-water, and rural locations across the northern Chesapeake Bay in ng/m3. Length of bar indicates concentrations and orientation indicates direction from which wind blew during the sampling period.

amounts were nearly identical at the two locations (3.11 and 4.41 mm of rain collected at Hart-Miller Island and Stillpond, respectively). Total (dissolved + particle bound) Σ-PAH concentrations were 179.4 and 43.4 ng/L, and total Σ-PCBs were 5.0 and 0.4 ng/L, over-water and rural, respectively, (see Figure 7). Particles contained within the precipitation delivered the greatest portion of the contaminants, with 94.5% and 81.5% of the Σ-PAHs, and 83% and 49% of the Σ-PCBs in the filter retained phase (over-water and rural, respectively). Although the total concentrations and relative strength of particle-bound fraction decreased further downwind of the urban center, the fingerprints of individual compounds did not change significantly between the two locations. The concentration of total Σ-PCBs in precipitation collected at the rural station is slightly lower than the volume weighted mean (VWM) concentration of 1.6 ng/L measured along the central Chesapeake Bay in 1991, though it is well within the reported range of 0.04–34 ng/L.22 Similarly, the concentration of Σ-PAH at the rural station falls close to the VWM concentration along the central Chesapeake Bay (59 ng/L).22 These measured Σ -PCB concentrations in rain are also similar to VWM concentrations measured over southern Lake Michigan and downwind of Chicago in southern Michigan which averaged 5.8 and 0.1 ng/L, respectively.9 The decreased concentration away from 964 Journal of the Air & Waste Management Association

SUMMARY During this preliminary investigation into the influence of elevated urban concentrations extending over the northern Chesapeake Bay, a strong concentration gradient was observed along the urban to rural transect sampled. Westerly winds increased total ΣPAH three-and-one-half-fold relative to non-westerly

Figure 7. Precipitation concentrations of individual PAHs and Σ-PCBs in ng/ L at Hart-Miller Island and Stillpond, MD, on June 4, 1996. Volume 49 August 1999

Offenberg and Baker


winds, both in downtown Baltimore and at the over-water locations, while no increase was observed at the rural location located on the eastern shore of the northern Chesapeake Bay. These increased urban concentrations, due mainly to gas phase increases, do not extend across the Chesapeake Bay, likely due to enhanced deposition rates. Additionally, particle-bound and gas phase PAHs appear to vary independently in Baltimore. There is likely a strong source area of particle-bound PAHs between the downtown and over-water locations, while the dominant source of gas PAHs seems to be located further inland, possibly over the urban center. Additionally, a strong source of gas phase PCBs appears to lie between the downtown and over-water locations. The elevated levels of urban atmospheric contaminants measured in this study extend approximately 30 km downwind of the greater Baltimore urban area. ACKNOWLEDGMENTS The authors would like to thank Rick Nolan and the staff of Fort McHenry National Monument and Historic Shrine for access to the urban sampling site, and Ed Adams and the staff of Maryland Environmental Services for access to the Hart-Miller Island sampling site. Additionally, the authors gratefully acknowledge Bernard C. Crimmins and Holly A. Bamford for help with sample collection. This research was supported by the U.S. Environmental Protection Agency through Grant CR 822046 and by the Maryland Department of the Environment through Grant U00P6002389. This is Contribution No. 3084 of the University of Maryland’s Center for Environmental Science.

10. Holson, T.M.; Noll, K.E.; Liu, S.P.; Lee, W.J.; Lin J.M.; Keeler, G.J. Environ. Sci. & Technol. 1993, 27, 1327–1333. 11. Pirrone, N.; Keeler, G.J.; Holson, T.M. Environ. Sci. & Technol. 1995, 29, 2123–2132. 12. Simcik, M.F.; Eisenreich, S.J.; Golden, K.A.; Liu, S.-P.; Lipiatou, E.; Swackhamer, D.L.; Long, D.T. Environ. Sci. & Technol. 1996, 30, 3039–3046. 13. Murphy, T.J.; Rzeszutko, C.P. J. Great Lakes Res. 1977, 3, 305. 14. Bamford, H.A.; Offenberg, J.H.; Larsen, R.K.; Ko, F.C.; Baker, J.E. Environ. Sci. Technol. 1999, 33, 2138-2144. 15. Baker, J.E.; Leister, D.L.; Clark, C.A.; Church, T.M.; Scudlark, J.R.; Ondov, J.M.; Dickhut, R.M.; Cutter, G. In Atmospheric Deposition of Contaminants to the Great Lakes and Coastal Waters, Baker, J.E., Ed.; Society of Environmental Toxicology and Chemistry: Pensacola, FL, 1997; pp 171–194. 16. Simcik, M.F. Ph.D. dissertation, Rutgers University, New Brunswick, NJ, 1997. 17. Caffrey, P.F. Ph.D. dissertation, University of Maryland, College Park, MD, 1997. 18. Simcik, M.F.; Franz T.P.; Zhang, H.; Eisenreich, S.J. Environ. Sci. & Technol. 1998, 32, 251–257. 19. Caffrey, P.F.; Ondov, J.M.; Zufall, M.J.; Davidson, C.I. Environ. Sci. & Technol. 1998, 32, 1615–1622. 20. Zufall, M.J.; Davidson, C.I.; Caffrey, P.F.; Ondov, J.M. Environ. Sci. & Technol. 1998, 32, 1623–1628. 21. Kucklick, J.R.; Harvey, H.R.; Ostrom, P.H.; Ostrom, N.E.; Baker, J.E. Environ. Toxicol. & Chem. 1996, 15, 1388–1400. 22. Leister, D.L.; Baker, J.E. Atmos. Environ. 1994, 28, 1499–1520. 23. Cotham, W.E.; Bidleman, T.F. Environ. Sci. & Technol. 1995, 29, 2782–2789. 24. Panshin, S.Y.; Hites, R.A. Environ. Sci. & Technol. 1994a, 28, 2008–2013. 25. Hornbuckle, K.C.; Achman, D.R.; Eisenreich, S.J. Environ. Sci. & Technol. 1992, 27, 87–98. 26. Hoff, R.M.; Strachan, W.M.J.; Sweet, C.W.; Chan, C.H.; Shackelton, M.; Bidleman, T.F.; Brice, K.A.; Burniston, D.A.; Cussion, S.; Gatz, D.F.; Harlin, K.; Schroeder, W.H. Atmos. Environ. 1996, 30, 2505–2527. 27. McConnell, L.L.; Kucklick, J.R.; Bidleman, T.F.; Ivanov, G.P.; Chernyak, S.M. Environ. Sci. & Technol. 1996, 30, 2975–2983. 28. Panshin, S.Y.; Hites, R.A. Environ. Sci. & Technol. 1994b, 28, 2001–2007.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

Andren, A.W.; Strachan, J.W. In Atmospheric Pollutant in Natural Waters, Eisenreich, S.J., Ed.; Ann Arbor Sciences: Ann Arbor, MI, 1981. McVeety, B.D.; Hites, R.A. Atmos. Environ. 1989, 22, 511–536. Baker, J.E.; Eisenreich, S.J. Environ. Sci. & Technol. 1990, 24, 342–352. Strachan, W.M.J.; Eisenreich, S.J. Mass Balancing of Toxic Chemicals in the Great Lakes: the Role of Atmospheric Deposition; International Joint Commission: Windsor, Ontario, 1988, p. 113. Hornbuckle, K.C.; Sweet, C.W.; Pearson, R.F.; Swackhamer, D.L.; Eisenreich, S.J. Environ. Sci. & Technol. 1995, 29, 869–877. McConnell, L.L.; Cotham, W.E.; Bidleman, T.F. Environ. Sci. & Technol. 1993, 27, 1304–1311. Simcik, M.F.; Zhang, H.; Eisenreich, S.J.: Franz, T.P. Environ. Sci. & Technol. 1997, 31, 2141–2147. Zhang, H.; Eisenreich, S.J.; Franz, T.P.; Baker, J.E.; Offenberg, J.H. Environ. Sci. Technol. 1999, 33, 2129-2137. Offenberg, J.H.; Baker, J.E. Environ. Sci. & Technol. 1997, 31, 1534–1538.


About the Authors Joel E. Baker is professor at the University of Maryland’s Chesapeake Biological Laboratory in Solomons, MD. John H. Offenberg conducted the research described here while a Ph.D. candidate at the University of Maryland, and is now a research chemist at the Statoil Research Centre in Trondheim, Norway. Baker (corresponding author) can be reached by e-mail at [email protected] or by fax at 410-326-7341.
