Pahs In Antartic

The Science of the Total Environment 229 Ž1999. 65]71

Quantification of polycyclic aromatic hydrocarbons in soil at McMurdo Station, Antarctica David Mazzeraa,U , Terry Hayes b, Douglas Lowenthal a , Barbara Zielinskab a

Atmospheric Sciences Center (ASC), Desert Research Institute, 2215 Raggio Parkway Reno, NV 89512-1095, USA b Energy and En¨ ironmental Engineering Center (EEEC), Desert Research Institute, 2215 Raggio Parkway Reno, NV 89512-1095, USA Received 1 September 1998; accepted 1 March 1999

Abstract Polycyclic aromatic hydrocarbons ŽPAHs. are a group of compounds that have attracted much attention over the past several years. The United States Environmental Protection Agency ŽUSEPA. has identified numerous PAHs as known or probable human carcinogens. The quantity of PAHs in the environment has dramatically increased, with the majority emitted from fossil fuel combustion sources. Surface soil samples were collected at McMurdo Station, Antarctica Ž778519 S, 1668419 E., during peak summer activity and analyzed for PAHs. PAHs were detected at several locations, with maximum concentrations for naphthalene, acenaphthene, acenaphthylene, and fluoranthene at 27 000, 17 800, 15 700, and 13 300 mgrkg, respectively. Results suggest anthropogenic activities may be contributing to increased levels of PAHs present in McMurdo soils. Q 1999 Elsevier Science B.V. All rights reserved. Keywords: PAHs in soils; McMurdo Station; Antarctica

1. Introduction Polycyclic or polynuclear aromatic hydrocarbons ŽPAHs. have been the focus of much attention over the past decade. The identification of numerous unsubstituted PAHs as priority pollutants by the United States Environmental Protec-

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Corresponding author. Tel.: q1-775-677-3203; fax: q1775-677-3157; e-mail: [email protected]

tion Agency ŽUSEPA, 1985. has been the driving force for both development of new and improvement of existing analytical methods for detection of PAHs in air, soil, sediment, and water. PAH compounds are introduced into the environment by natural and anthropogenic Žmanmade. sources. Natural sources include forest fires. Anthropogenic sources and activities that generate PAHs include fossil fuel combustion Ži.e. mobile sources, power plants. and practices such as agricultural burning. A study by Basu and

0048-9697r99r$ - see front matter Q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 8 - 9 6 9 7 Ž 9 9 . 0 0 0 6 5 - 0

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Saxena Ž1987. has shown a correlation between increases in PAH concentrations in environmental media with sites where fossil fuels and refining waste residuals were used or produced. On a smaller scale, everyday activities such as woodburning stoves and fireplaces, meat grilling, and the use of gasoline-powered equipment Žlawn mowers. may contribute to total PAH contributions in urban areas ŽFreeman and Cattell, 1990.. Concentrations of PAHs in ‘ambient’ soils have been measured since the early 1970s. Virtually all surface soils have measurable PAH concentrations due mainly to the transport of these compounds in the atmosphere and subsequent dry and wet deposition processes as well as scrubbing of these organic molecules by forest canopies and deposit in soils via litterfall ŽMatzner, 1984.. Jones et al. Ž1989. have shown typical concentrations in forest soils range from 5 to 100 m grkg Žparts per billion, ppb. and result from both natural and anthropogenic sources. Results from analysis of soil samples collected and preserved from 1880 to the present have shown a general increase in PAH concentrations, with levels peaking during the 1950sr1960s ŽMenzie et al., 1992.. As one may expect, urban and metropolitan areas typically have higher concentrations of PAHs due to an increase in point and non-point sources as well as an increase in fossil fuel combustion and other incineration processes. Antarctica is considered to be one of the last pristine environments on earth. However, even in such remote environments there exists evidence of human contamination. While humans have been present in Antarctica for decades, the growing numbers in recent years increase the potential for contamination. During the austral summer, McMurdo serves as a major base for many of the outlying field camps and research bases. McMurdo’s population exceeds 1000 during peak activity. The purpose of this study is to examine the levels of PAHs found in Antarctic soils located in the vicinity of McMurdo Station, the United States base located on Ross Island, Antarctica Ž778519 S, 1668419 E.. Soil samples collected were analyzed for a suite of PAHs in order to assess the impact

of human activity on the level of these compounds present in such a remote location. These observations will contribute to the growing database of contamination impacting the environment on a global scale.

2. Materials and methods 2.1. Soil sampling Collection of soil samples Ž n s 20. was performed in January 1997, during peak seasonal activity at McMurdo. Surface soil grab samples Ž0]2 inches. were collected at 18 locations around McMurdo Station ŽFig. 1.. Two additional samples were collected from the exposed soils at the Lake Hoare Long Term Ecological Research ŽLTER. basecamp, located approximately 90 km northeast and downwind of McMurdo in Taylor Valley, Antarctica. All soil samples were stored frozen in certified clean amber glass containers with minimal light exposure until the time of extraction and analysis. 2.2. Extraction and analysis The soil samples were Soxhlet-extracted separately with dichloromethane ŽDCM. using a modified EPA Method 3540B for a minimum of 18 h ŽUSEPA, 1994.. Approximately 30 g of the soil samples were mixed with approximately 5 g of oven-dried sodium sulfate and placed in an extraction thimble. The extracts were concentrated by rotary evaporation at 208C under gentle vacuum to 1 ml and filtered through a 0.20-m m Anatop filter ŽWhatman International, Ltd.., rinsing the sample flask twice with 1 ml DCM. Approximately 50 m l of acetonitrile was added to the sample and the DCM was evaporated under a nitrogen gas stream. The final volume was adjusted to 1 ml with acetonitrile. The sample was then analyzed by electron impact ŽEI. GCrMS, using a Hewlett-Packard 5890 GC equipped with a 7673A automatic sampler and interfaced to a 5970B mass selective detector ŽMSD.. Injections Ž1-m l. were made in splitless mode onto a 60-m= 0.25-mm ID DB-5 fused-silica capillary column

D. Mazzera et al. r The Science of the Total En¨ ironment 229 (1999) 65]71

Fig. 1. Ross Island and McMurdo Station, Antarctica, with soil sample locations.

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D. Mazzera et al. r The Science of the Total En¨ ironment 229 (1999) 65]71

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ŽJ &W Scientific Inc... Identification and quantification of the PAH were made by multiple ion detection ŽMID., monitoring the molecular ion of each PAH, and deuterated PAH standards. Prior to extraction, the following deuterated internal standards were added to each soil sample: naphthalene-d 8 ; acenaphthylene-d 8 ; phenanthrene-d 10 ; anthracene-d 10 ; chrysene-d 12 ; fluoranthene-d 10 ; pyrene-d 10 ; benzw axanthracene-d 12 ; b en zo w e x pyren e-d 1 2 ; b en zo w a x pyren e-d 1 2 ; benzow k xfluoranthene-d 12 ; and benzow ghi xperylene-d 12 . NIST SRM 1647 Žcertified PAH., with the addition of deuterated internal standards and authentic standards of compounds not present in the SRM, were used to make calibration solutions. Calibration curves for the GCrMSrMID quantification were made for the molecular ion peaks of the PAH using the corresponding deuterated species Žor the deuterated species most closely matched in volatility and retention characteristics as internal standards.. The soil samples were corrected for moisture content and results were reported in m grkg on a dry weight basis.

Practical quantitation limits ŽPQLs. were calculated based on minimum detection limits ŽMDLs.. MDL values are based on seven replicate analyses of the lowest standard for each PAH of interest. The final MDL values are three times the standard deviation of the replicate sets. The compound-specific PQLs were then calculated by taking the MDLs and accounting for an average soil sample mass of 0.0309 kg, on a dry-weight basis, for each PAH. Compound-specific PQLs are listed in Table 1 for samples with concentrations detected above the MDLs.

3. Results and discussion PAH concentrations detected in soils in the vicinity of McMurdo Station, Antarctica, are listed in Fig. 2. The highest concentrations detected were in soils located in unpaved roadbeds near the sea water intake Žlocation 5. and the gasoline pumps Žlocation 10.. It is most likely that soil samples collected in these areas were contami-

Table 1 Number of detections, MDL, PQL, average, and maximum Žin ppb. per PAH a

Naphthalene Biphenyl Acenaphthylene Acenaphthene Phenanthrene Fluorene Anthracene Fluoranthene Pyrene Benzw axanthracene Chrysene Benzow e xpyrene Dibenzow ahq ac xpyrene Benzow b xchrysene Coronene a

No. detectedr totalb

Abbreviation

MDLc

PQLd

Averagee

Maximumf

Site ID

4r20 3r20 3r20 3r20 4r20 3r20 2r20 5r20 6r20 3r20 3r20 1r20 1r20 1r20 1r20

NAP BIP ACY ACE PHE FLE ANT FLA PYR BAA CHR BEP DAP BBC COR

0.027 0.012 0.063 0.030 0.0060 0.0150 0.0060 0.0180 0.0120 0.030 0.0150 0.0090 0.039 0.021 0.069

0.88 0.39 2.0 0.97 0.194 0.49 0.194 0.58 0.39 0.97 0.49 0.29 1.26 0.68 2.2

6700 " 1300 640 " 190 5500 " 3500 6000 " 730 160 " 15 580 " 38 2500 " 370 2700 " 250 28 " 3.4 510 " 0.78 570 " 90.0 250 " 45 320 " 1.8 2700 " 2500 670 " 3.2

27 000 " 2600 1710 " 360 15 700 " 6300 17 800 " 1270 540 " 30 1590 " 69 5000 " 650 13 300 " 430 132 " 6.4 1420 " 1.38 1630 " 160 250 " 45 320 " 1.8 2700 " 2500 670 " 3.2

5 5 5 5 5 5 5 5 5 10 5 5 5 5 5

Uncertainty values are analytical uncertainties for individual samples or standard deviations for more than one sample. Number of detections above minimum detection limit ŽMDL. out of 20 soil samples collected. c Minimum detection limit equals three times the standard deviation of the replicate analysis of lowest standards. d PQL, practical quantitation limit, in m grkg soil Žppb.. Refer to text, Section 2.2. e Samples with single detection, ‘average’ value equals value reported for single detection. f This column presents the maximum concentration detected with the corresponding site identified in the next column. b

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nated by spillage of fuels or oils from vehicles containing PAHs of interest. In addition, the following soil sample locations all contained de-

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tectable levels of PAHs of interest: downslope from the power plant Žlocation 1.; the dirt roadway ramp from the ice aircraft runway Žlocation

Fig. 2. Summary of PAH concentrations detected in soil Žppb. per sample location.

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3.; the lower helicopter pad Žlocation 6.; an unpaved roadway in the retrograde yard Žlocation 12.; the vicinity of Tank 98, a JP-8 diesel fuel storage tank Žlocation 14.; and the unpaved convergence of several roadways between buildings 136 and 120 Žlocation 20.. The two soil samples collected from the Taylor Valley did not have any detectable levels of PAHs. The presence of a Long Term Ecological Research basecamp at Lake Hoare represents a community of approximately 4]10 scientists during the austral summer. Activities that may produce PAHs in this area include helicopter loading and unloading, electrical generation from a diesel-fueled generator, burning of solid sewage in small incinerator toilets, and use of small allterrain vehicles. Samples were collected on the upwind and downwind sides of the helicopter pad, using the same protocol as for the McMurdo samples. While the sensitivity of analyses may have played a role in detecting any PAHs present in these samples Žsee Table 1 for MDLs and PQLs., one may conclude that activities at Lake Hoare are not of sufficient magnitude to generate detectable quantities of PAHs. In addition, these results suggest any downwind transport of PAHs from McMurdo is not detectable. Regarding McMurdo soils, the following are high-probability reasons for the presence of PAHs detected at each of the above mentioned locations: Ž1. soils near the power plant are likely to contain PAHs deposited from stack emissions from the diesel generators as the prevailing winds are generally downslope towards McMurdo Sound; Ž2. the dirt ramp to the ice runway is a site of heavy vehicular traffic during the runway’s operations and PAHs are most likely present from both light and heavy duty vehicles burning gasoline and diesel; Ž3. the lower helicopter pad is the sight of the most helicopter operations, and PAHs present are likely due to helicopter exhaust and or re-fueling operations; Ž4. the retrograde yard functions as a location for the recycling, destruction and packaging for transport of used materials where heavy equipment, operating on a regular basis, may be a likely source for PAHs detected. While tank 98 is used for storage of JP-8 fuel, it is difficult to determine the likely

source of PAHs detected in this vicinity. Similarly, it is difficult to determine the likely source of pyrene, a PAH, detected between buildings 136 and 120, unless vehicular traffic in this location has acted as a source of pyrene in soils. Building 136 has been used as office space and repair and construction shops. The types of designated pollutants stored included solvents, oils and lubricants, paints and primers, and copier tonerŽASA, 1994.. Table 1 summarizes the results of the 20 soil samples collected. Pyrene had the greatest number of detections above the MDL Ž6 total., followed by fluoranthene Ž5 total. and phenanthrene and naphthalene Ž4 total.. The highest average and maximum concentrations detected were for naphthalene Žave s 6700 " 1300 m grkg, max s 27 000 " 2600 m grkg. followed by acenaphthene Ž ave s 6000 " 730, m ax s 17 800 " 1270 m grkg . ,acenaphthylene Ž ave s 5500 " 3500 m grkg, max s 15 700 " 6300 m grkg. and fluoranthene Žave s 2700 " 250 m grkg, max s 13 300 " 430 m grkg.. These ranges in concentrations between different PAH species may be due to different proportions formed during combustion processes. Proportions of each PAH species produced depends on several conditions, for example, fuel type and composition, and combustion temperature. The data from this study suggest that there is a measurable anthropogenic input of PAH into the local environment at McMurdo Station. Kennicutt et al. Ž1995. report sediment PAH levels in McMurdo Sound in the ranges of 6267]6339 ppm for the austral Summers of 1990r1991 and 1992r1993. The predominant explanation for such high concentrations in the sound immediately adjacent to McMurdo is from the runoff from adjacent land areas. The concentrations we have reported are within the range of concentrations typically reported for forest soils Ž5]100 ppb. ŽMenzie et al., 1992. with the exception of several of the PAHs reported in the 1000]27 000 m grkg Žppb. range Žsee maximum concentrations reported above.. One must keep in mind that these samples represent a general survey of the range of PAHs that are present in soils in the vicinities of Lake Hoare and McMurdo Station, Antarctica. The concentrations detected may over-represent

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actual PAH concentrations if one takes into account random sampling of point sources Že.g. oil and fuel spills. that are small in number but may contain high levels of PAHs. Conversely, concentrations may be underestimated if one takes into account physical and biological degradation processes Žlikely to be minimal in this type of environment. as well as dilution and dispersion from non-point combustion sources.

4. Conclusions The results of this study indicate that human activities have contributed to the overall levels of PAHs contaminating McMurdo Station, Antarctica. This study provides a potential source for the high levels of PAHs found in sediments in McMurdo Sound as reported by Kennicutt et al. Ž1995.. PAHs from local soils transported in runoff from snow melt is a plausible explanation for elevated concentrations of these compounds in McMurdo Sound sediments. Further studies on sources of PAHs at McMurdo are needed to help reduce any potential elevation in concentrations of these high-profile semi-volatile organic compounds.

Acknowledgements The authors gratefully acknowledge the use of

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the inorganic and organic lab facilities at the Desert Research Institute, run under the direction of Dr Judith Chow and Dr Barbara Zielinska, respectively. References ASA. Master Permit Application ŽFinal.. Antarctic Support Associates ŽASA. and Consoer Townsend & Associates, vol. 1, 27 June 1994. Basu D, Saxena J. Comparison of drinking water mutagenicity with leaching of polycyclic aromatic hydrocarbons from water distribution pipes. Chemosphere 1987;16:2595]2612. Freeman D, Cattell F. Woodburning as a source of atmospheric polycyclic aromatic hydrocarbons. Environ Sci Technol 1990;24:1581]1585. Jones K, Stratford J, Waterhouse K et al. Increases in the polynuclear aromatic hydrocarbon content of an agricultural soil over the last century. Environ Sci Technol 1989;23:95]101. Kennicutt II M, McDonald S, Sericano J et al. Human contamination of the marine environment } Arthur Harbor and McMurdo Sound, Antarctica. Environ Sci Technol 1995;29:1279]1287. Matzner E. Annual rates of deposition of polycyclic aromatic hydrocarbons in different forest ecosystems. Water Air Soil Pollut 1984;21:425]434. Menzie C, Potocki B, Santodonato J. Exposure to carcinogenic PAHs in the environment. Environ Sci Technol 1992;26:1278]1284. United States Environmental Protection Agency ŽUSEPA.. Evaluation and estimation of potential carcinogenic risks of polynuclear aromatic hydrocarbons: carcinogen assessment group. Washington, DC: Office of Health and Environmental Assessment, 1985. USEPA. SW846 reference methodology: method 3540B-Soxhlet Extraction. Revision 2, September 1994.