# Polybrominated diphenyl ether flame retardants in lichens and mosses from King George Island, maritime Antarctica

G.T. Yogui * 

## , J.L. Sericano

Geochemical and Environmental Research Group, College of Geosciences, Texas A&M University, 833 Graham Road, College Station, TX 77845, USA



### article info

Article history: Received 5 July 2008 Received in revised form 25 August 2008 Accepted 26 August 2008 Available online 11 October 2008

Keywords: PBDEs Persistent organic pollutants Sanionia uncinata Usnea antarctica Usnea aurantiaco-atra Antarctic Peninsula 

### abstract

Lichens and mosses are considered good indicators of atmospheric pollution as they absorb contaminants directly from the air. Polybrominated diphenyl ethers (PBDEs) are man-made chemicals used as flame retardants in materials such as plastics, textiles, electronic circuitry and furnishing foam. Few studies have investigated PBDEs in the southern hemisphere including Antarctica. This paper presents the first evaluation of PBDEs in lichens ( Usnea antarctica and Usnea aurantiaco-atra ) and mosses (Sanionia uncinata ) collected at King George Island, maritime Antarctica. PBDEs were detected at low levels in all lichen and moss samples. On average, the levels of PBDEs in mosses (818 pg g

1 dry weight; 101 ng g

1 lipid) were significantly higher than in lichens (168 pg g

1 dry weight; 9.11 ng g

1 lipid). This difference is most likely due to the differing mechanisms of PBDEs uptake from the atmosphere which are controlled by anumber of chemical, environmental and plant variables. Contaminant concentrations were not statistically different at sites close to and distant from human facilities. Long-range atmospheric transport is believed to be the primary source of PBDEs to King George Island. The pattern of congeners in plants resembles those found in commercial mixtures of Penta-BDE. In addition, the presence of BDE-183 in lichens and mosses suggests that other technical formulations (e.g., Octa-BDE and Deca-BDE) have reached Antarctica. Further studies are needed to better understand the role of Antarctic vegetation as a sink for anthropogenic organic pollutants.
2008 Elsevier Ltd. All rights reserved.

1. Introduction

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants to prevent the risk of fire in polymeric materials (e.g., plastics, textiles and furnishing foam). Historically, the world production of these chemicals has been limited to few companies located in the northern hemisphere ( de Wit, 2002 and referencestherein). However, there is evidence of their widespread distribution throughout the global environment (e.g., de Boer et al., 1998; Corsolini et al., 2006; de Wit et al., 2006 ). Some authors have argued that PBDEs qualify as persistent organic pollutants (POPs) due totheir long-range transport, persistency in the environment, bioaccumulation and toxicity to organisms (e.g., de Wit et al., 2006 ). Vegetation has been used to monitor organic pollution since the early 1980s (see Buckley, 1982 ). The major uptake mechanism of lipophilic organic contaminants by vegetation is partitioning from air to plant tissue at the leaf surface. This pathway is a function ofthe physical–chemical properties of the contaminant (e.g., lipophilicity and vapor pressure), environmental conditions (e.g., temperature) and plant species ( Simonich and Hites, 1995 ). Furthermore, Morosini et al. (1993) have found a correlation between levels of organic contaminants in vegetation and the surrounding air, suggesting that vegetation integrates atmospheric contamination over time. The distribution of terrestrial vegetation in Antarctica is limited to ice-free areas which are primarily found along the mainland coast and adjacent islands. Plant species have been recorded throughout Antarctica from its northernmost limit (60 S, according to the Antarctic Treaty) poleward to the Trans Antarctic Mountains at latitude of 86 S ( Peat et al., 2007 ). Plant communities are dominated by lower plants (predominantly lichens and mosses) and biodiversity tends to decline with increasing latitude. Peat et al. (2007) divided the Antarctic flora into three major provinces namely northern maritime, southern maritime and continental. Species richness is highest in the northern maritime Antarctica and is characterized by approximately 350 lichens, 115 mosses, 27 liverworts and 2 phanerogams ( Peat et al., 2007 ). The lichens Usnea antarctica Du Rietz and Usnea aurantiaco-atra (Jacq.) Bory along with the moss Sanionia uncinata (Hedw.) Loeske are commonly found in the Antarctic tundra ( Osyczka et al., 2007 ). U. antarctica has a circumpolar distribution with greatest abundances along the Antarctic Peninsula. U. aurantiaco-atra is lessubiquitous than its counterpart and is restricted to the South Orkney Islands, South Shetland Islands and the Antarctic Peninsula. The moss S. uncinata is a bipolar species and has widespread

0045-6535/$ - see front matter 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2008.08.035

* Corresponding author. Tel.: +1 979 862 2323x167; fax: +1 979 862 2361.

E-mail address: gtyogui@ocean.tamu.edu (G.T. Yogui). Chemosphere 73 (2008) 1589–1593

Contents lists available at ScienceDirect 

# Chemosphere

journal homepage: www.elsevier .com/locate/chemospheredistribution along the western Antarctic Peninsula ( Smith, 1996; Øvstedal and Lewis-Smith, 2001; Shaw, 2001 ). These three specieshave been used as bioindicators of atmospheric pollution in Antarctica because of their dominant occurrence in ice-free areas and ease of sampling (e.g., Mietelski et al., 2000; Osyczka et al., 2007 ). Monitoring studies using lichens and mosses in the westernAntarctic Peninsula have investigated trace metals, radioactive elements and chlorinated hydrocarbons ( Bacci et al., 1986; Poblet et al., 1997; Godoy et al., 1998; Olech et al., 1998; Mietelski et al., 2000; Schuller et al., 2002; Osyczka et al., 2007 ). There appears to be no data published on PBDEs in Antarctic vegetation. This study presents the first evaluation of PBDEs in the lichens and mosses of King George Island, Antarctica.

2. Material and methods

2.1. Sampling and study area

King George is the largest island in the South Shetlands archipelago and is located approximately 120 km north of the Antarctic Peninsula ( Fig. 1 ). Over 90% of its 1300 km2 is ice-covered ( RakusaSuszczewski, 1980 ). Admiralty Bay is the largest fjord-like embayment on King George Island encompassing a surface area of 122 km2 ( Rakusa-Suszczewski et al., 1993 ). The coast of Admiralty Bay is fairly irregular alternating between gravel/sandy beaches, rocky shores and glaciers along its ca. 84 km long shoreline ( Rakusa-Suszczewski, 1995 ). Lichens and mosses were collected at 11 sampling sites during the austral summer 2005–2006 in ice-free, coastal areas of Admiralty Bay ( Fig. 1 ). Samples were collected byhand (with latex gloves) and thoroughly shaken to remove extraneous material such as animal-related debris and soil particles. All samples were stored in clean glass jars and frozen at

20 C as soon as possible.

2.2. Chemical analysis

All plant samples were homogenized in the laboratory prior to analysis. Extraction and clean-up followed standard procedures routinely used at the Geochemical and Environmental Research Group (GERG) and published elsewhere (e.g., Lauenstein and Cantillo, 1998 ). Briefly, approximately 10 g of wet plant tissue was mixed with 40 g of anhydrous sodium sulfate and extracted with 300 mL of dichloromethane using a tissumizer (PRO Scientific Inc., model PRO250). Plant extracts were extensively cleaned upwith sulfuric acid, silica/alumina chromatography and gel permeation chromatography/high performance liquid chromatography(GPC/HPLC). Dry and lipid weights were gravimetrically determined using an analytical balance following standard procedures used at the GERG facilities.

2.3. Instrumental parameters

Sample extracts were injected into a GC–MS (Agilent Technologies) in the selected ion monitoring (SIM) mode. A HP-5 ms capillary column (30 m length  0.25 mm id  0.25 

### lm film thickness) was used for separation of compounds. Helium was used as carrier gas under constant flow (0.8 mL min

1 ) into the column. The oven temperature was programmed as follows: 130 C for 1 min, ramped at 12 C min

1 to 154 C, ramped at 2 C min

1 to 210 C and ramped at 3 C min

1 to 300 C with a final hold time of 5 min. The mass spectrometer was operated in EI mode. The ionstacking technique was employed to increase the GC–MS sensitivity so that ultra-trace analyte concentrations could be detected (Yogui, 2008 ). This technique consists of recording the intensity of a particular ion several times during a single scan cycle of the MS detector. The SIM run was divided into seven functions where each m/z ion was recorded 6–12 times per scan cycle.

2.4. Quality control

Quality control criteria were based on Lauenstein and Cantillo (1998) and EPA (2003). Quantitation of the target analytes used isotope dilution and internal standard techniques. The following

13C-labeled standards were used: BDEs 15, 28, 47, 77, 99, 100, 118, 126, 153 and 183. The average recovery of internal standards was 66 ± 2.8% (95% level of confidence). In each analytical batch,

East Antarctica West Antarctica

60o W 58o W 56o W 63.5o S 62.5o S 61.5o S

King George Island South Shetland Islands

Bransfield Strait

A n t a rc tic

P e ni n s u l a

58.6o W 58.5o W 58.4o W 58.3o W 58.2o W 62.2oS 62.1oS Ferraz Station

(Brazil) King George Island

Field Station (Ecuador) Machu Picchu Station (Peru)

Arctowski Station (Poland) Pieter J.Lenie Field Station

(USA) 

### Admiralty Bay

5 km Bransfield Strait

Fig. 1. Location of the study area and sampling sites. Refer to Table 1 for sampling site codes. 1590 G.T. Yogui, J.L. Sericano / Chemosphere 73 (2008) 1589–1593two matrices were spiked with PBDEs and analyzed in duplicate. The mean recovery of PBDE standards in the spiked matrices was106 ± 3.9% (95% level of confidence). The relative percent difference (RPD) between the spiked duplicates was 17 ± 3% (95% level of confidence). The limits of detection for selected major PBDEs found in samples were 1.0 pg g

1 dry weight (BDEs 15, 47 and 49), 1.4 pg g

1 dry weight (BDEs 99 and 100) and 1.3 pg g

1 dry weight (BDEs 153 and 154).

2.5. Statistical analyses

Single-factor ANOVA and two-factor ANOVA (Model I, fixed effects) were performed to compare population means. The ANOVAis a robust, parametric test used to infer statistically significant differences between two or more population means. Assumptions of the test are: (1) data are independent and continuous; (2) data are approximately normally distributed; and (3) data set variances are homogeneous ( Dytham, 2003 ). Distribution of PBDEs in planttissues was skewed. So the data sets were transformed using natural logarithm to meet the assumptions of the ANOVA. This is avalid alternative as long as all data points are systematically converted using the same procedure ( Ott and Longnecker, 2001). Simonich and Hites (1995) recommended that concentration of organic pollutants in vegetation be normalized to lipid basis when comparing different species. This approach accounts for some of the variability due to biochemical differences in plants. In thisstudy, all statistical evaluations were performed on lipid-normalized data. The critical level of significance of the statistical analyses
was set at 

### a = 0.05.

3. Results and discussion

A suite of 36 di- through hepta-BDEs was measured including the following congeners: 7, 8, 10, 11, 12, 13, 15, 17, 25, 28, 30, 32, 33, 35, 37, 47, 49, 66, 71, 75, 77, 85, 99, 100, 116, 118, 119, 126, 138, 153, 154, 155, 166, 181, 183 and 190 (numeration according to the same IUPAC system used for PCBs). However, onlyBDEs 15, 28, 33, 47, 49, 66, 85, 99, 100, 153, 154 and 183 were detected above the method detection limits. It is important to note that hexa-BDEs (IUPAC Nos. 138, 153, 154, 155 and 166) could not be identified and quantified in the moss S. uncinata because of interfering peaks that remained in the extracts after extensive purification. The average total PBDEs in lichens of the species U. antarctica was 192 pg g

1 dry weight ( n = 6, SD = 93.9) while in the species U. aurantiaco-atra was 139 pg g

1 dry weight ( n = 5, SD = 33.6) (Table 1 ). According to the single-factor ANOVA, there is no significant difference between PBDEs in the two lichen species (F = 0.77, df = 1, p > 0.05). Poblet et al. (1997) also did not find a statistical difference in the accumulation of metals (Fe, Zn, Pb and Cd) by U. antarctica and U. aurantiaco-atra collected at King George Island. Genetic and morphological investigations have revealed a very close relationship between these two species, supporting the hypotheses that they might be a single species, or alternatively constitute a species pair where U. antarctica would be the sterile form and U. aurantiaco-atra the fertile form (Walker, 1985; Seymour et al., 2007 ). Based on these reports and the statistical results, both lichen species are pooled as a single species for purposes of comparison with mosses of the species S. uncinata

. Concentrations of PBDEs in lichens and mosses collected along the shore of Admiralty Bay are shown in Tables 1 and 2 . A two-factor model I (fixed effects) ANOVA was performed to determine the effects of plant species and human presence on concentration ofPBDEs. Each of the main factors (i.e., plant species and human presence) had two levels. Plant species was grouped as lichens and mosses, whereas human presence was grouped as sampling sitesclose to (sites A–F) and distant from (sites G–K) the Brazilian scientific station (see Fig. 1 ). The ANOVA indicated that PBDE levels

Table 1 Concentration of PBDEs (pg g

1 dry weight) in lichens collected along the shore of Admiralty Bay, King George Island, Antarctica

Site Location Species Dry weight (%) Lipid (%) BDE-47 (pg g

1 dry weight) BDE-99 (pg g

1 dry weight) BDE-100 (pg g

1 dry weight) P PBDEs (pg g

1 dry weight)
A Refuge 2 U. aurantiaco-atra 87.0 1.18 37.4 42.2 8.12 98.3 B Plaza Point U. antarctica 85.5 2.87 65.5 74.9 14.9 179 C Ferraz (chemistry) U. aurantiaco-atra 86.5 1.20 70.0 63.7 12.7 182 D Ferraz (VLF) U. aurantiaco-atra 85.2 1.10 49.9 41.4 8.58 116 E Stenhouse Point U. antarctica 89.4 2.01 48.7 42.9 8.20 114 F Ullman Point U. aurantiaco-atra 87.3 1.15 57.9 67.2 13.2 160 G Hennequin Point U. antarctica 82.2 2.02 64.0 72.6 14.8 176 H Vauréal Cape U. antarctica 87.7 1.94 138 155 32.5 377 I Demay Point U. antarctica 87.1 1.80 55.3 55.6 11.4 157 J Ezcurra Inlet U. aurantiaco-atra 86.9 1.61 54.1 58.6 11.4 140 K Machu Picchu U. antarctica 88.1 1.44 51.8 59.4 11.4 148 Average ± standard deviation 86.6 ± 1.9 1.67 ± 0.54 63.0 ± 26.5 66.7 ± 31.7 13.4 ± 6.8 168 ± 75

Table 2 Concentration of PBDEs (pg g

1 dry weight) in mosses collected along the shore of Admiralty Bay, King George Island, Antarctica

Site Location Species Dry weight (%) Lipid (%) BDE-47 (pg g

1 dry weight) BDE-99 (pg g

1 dry weight) BDE-100 (pg g

1 dry weight) P PBDEs (pg g

1 dry weight)
A Refuge 2 S. uncinata 55.9 0.278 403 402 80.2 960 B Plaza Point S. uncinata 49.0 0.493 377 564 106 1137 C Ferraz (chemistry) S. uncinata 18.2 0.128 303 457 100 883 D Ferraz (VLF) S. uncinata 33.9 0.114 132 130 36.5 319 E Stenhouse Point S. uncinata 72.8 1.41 206 312 82.5 630 F Ullman Point S. uncinata 41.4 0.328 180 250 71.4 538 G Hennequin Point S. uncinata 55.7 0.379 193 283 69.9 584 H Vauréal Cape S. uncinata 12.4 0.124 404 579 123 1184 I Demay Point S. uncinata 71.5 1.37 375 513 81.8 1020 J Ezcurra Inlet S. uncinata 13.2 0.105 315 383 93.2 834 K Machu Picchu S. uncinata 70.3 0.799 343 431 81.8 912 Average ± standard deviation 44.9 ± 23.0 0.50 ± 0.49 294 ± 99 391 ± 139 84.2 ± 22.3 818 ± 270 G.T. Yogui, J.L. Sericano / Chemosphere 73 (2008) 1589–1593 1591were not influenced by main factors interaction (F = 0.12, df = 1,
p > 0.05). The mean total PBDEs in mosses was significantly higher than in lichens (F = 144, df = 1, p < 0.0001). However, there was no significant difference in contamination levels close to (sites A–F) and distant from (sites G–K) the Brazilian scientific station (F = 0.07, df = 1, p > 0.05).Along the shore of Admiralty Bay, there are three scientific stations (Arctowski, Poland; Ferraz, Brazil; and Machu Picchu, Peru) and two field stations (USA and Ecuador). Arctowski and Ferraz are occupied year round while the others have activities limited to summer (and are often unoccupied even in the summer in the case of Peru and Ecuador). Considering that Ferraz is the largest station in Admiralty Bay, it is reasonable to assume that it willcause the greatest human impact in the area. The statistical analysis revealed no contamination difference in sampling sites close to and distant from Ferraz station, suggesting that station activitiesare not a significant source of PBDEs to the local environment. Indeed, no significant local input of POPs (e.g., PCBs) has been detected in the area and long-range atmospheric transport is believed to be the primary source of these chemicals to Admiralty Bay ( Montone et al., 2003; Montone et al., 2005 ). In contrast, a recent study found high PBDE levels in indoor dust and wastewater sludge from McMurdo (USA) and Scott (New Zealand) research bases, showing that human activities may be a local source of PBDEs to the Antarctic environment ( Hale et al., 2008 ). McMurdo and Scott bases – located within 3 km from each other – host over1000 people during the summer. This far exceeds human occupation at the Brazilian station which hosts approximately 50 people each summer. Taking into account the recent findings of Hale et al. (2008), local sources of PBDEs to Admiralty Bay cannot be totally ruled out. Human facilities such as the Brazilian and the Polish stations may be a complimentary source of brominated flame retardants to the local environment. It is suggested that PBDEs be analyzed in indoor dust and wastewater sludge of local research stations in order to investigate their potential as local sources of contaminants. The average percent distribution of PBDEs in lichens and mosses was similar ( Fig. 2 ). Tetra-BDEs represented 38% of the total PBDEs in both lichens and mosses, whereas penta-BDEs averaged 47% inlichens and 58% in mosses. This is similar to commercial formulations of Penta-BDE which are 24–38% tetra-BDEs, 50–60% pentaBDEs and 4–8% hexa-BDEs ( de Wit, 2002 ). Congener patternsimilarities between Antarctic vegetation and the Penta-BDE mixture suggest that PBDEs do not undergo major fractionation during their long-range transport to Antarctica although minor fractionation may occur. IUPAC Nos. 47, 99 and 100 were the three major congeners detected in all samples, accounting for more than 75% of total PBDEs. This agrees with other studies worldwide (see de Wit, 2002 ).Di- and tri-BDEs occur at trace amounts in Penta-BDE formulations ( La Guardia et al., 2006 ). Minor proportions of BDE-15 and BDE-28/33 (co-eluted) in the Antarctic samples may be explainedby either global fractionation or degradation of more highly brominated congeners. Global fractionation preferentially transports more volatile chemicals to sites farther away from their emission areas as compared to less volatile organic compounds (Wania and Mackay, 1993 ). It has also been reported that PBDEs undergo photochemical debromination (e.g., Eriksson et al., 2004; Keum and Li, 2005; Ahn et al., 2006; Rayne et al., 2006 ). Thus, it is reasonable to assume that transformation processes may alter PBDE mixtures during long-range atmospheric transport to Antarctica. In addition, degradation might also take place at the plant surface as suggested by Simonich and Hites (1995). Detection of the heptabrominated BDE-183 in lichens and mosses implies that technical mixtures other than the Penta-BDE formulation have reached the Antarctic environment. BDE-183 is a major congener present in the Octa-BDE product ( La Guardia et al., 2006 ). According to Bezares-Cruz et al. (2004)

, BDE-183 may also be a degradation productof BDE-209 which is the dominant congener in the Deca-BDE formulation – the most widely produced PBDE commercial mixture. Differences in contamination of lichens and mosses are most likely associated with processes responsible for PBDEs uptake from the atmosphere which are complex and may be governed by anumber of chemical, environmental and plant parameters. HexaBDEs (i.e., BDEs 153 and 154) represented approximately 8% of the total PBDEs in lichens. Taking into consideration that thesecongeners could not be measured in mosses and are usually detected in environmental samples, it is reasonable to suggest that PBDEs concentrations in mosses are somewhat higher than the reported values. This confirms the differences observed in theANOVA that higher levels of PBDEs occur in mosses when compared to lichens. Other pollution monitoring studies in the western Antarctic Peninsula have observed differential contaminant accumulation in lichens and mosses. Osyczka et al. (2007) found greater concentration of trace elements in the moss S. uncinata when compared to lichens U. antarctica and U. aurantiaco-atra

. Mietelski et al. (2000)observed fractionation of radionuclides between mosses and lichens. While S. uncinata is non-selective with regard to 137Cs and

241 Am from atmospheric fallout, these radioactive elements seem to be leached out of U. antarctica and U. aurantiaco-atra

. Godoy et al. (1998) also observed greater accumulation of 137Cs in several moss species in comparison with lichens from the South Shetland Islands. There are few data published on PBDEs in lichens and mosses. Acomprehensive study in northern Russia collected plants (including lichens and mosses) from several sites (AMAP, 2004 ). However, BDEs 47 and 99 were not found above the limit of detection (0.2 ng g

1 dry weight) in any sample (AMAP, 2004 ). Moss samples from two locations in Norway revealed total PBDE concentrations of 149 pg g

1 wet weight and 328 pg g

1 wet weight ( de Wit et al., 2006 and a reference therein). These levels are similar to those reported here. On a wet basis, the mean total PBDEs in mosses collected at King George Island was 363 pg g

1 wet weight (range: 108–729 pg g

1 wet weight). In the 1980s, Bacci et al. (1986) investigated chlorinated hydrocarbons in mosses and lichens of the western Antarctic Peninsula. Levels of HCB, 

### a-HCH, 

### c-HCH, p,p0 -DDT and p,p0 -DDE at that time are comparable to levelsof PBDEs reported in this study (carried out 20 years later). However, the concentration of PCBs measured in the 1980s is an order 0 20 40 60 80

di- tri- tetra- penta- hexa- heptaBDE Homolog SeriesPercentage (%) Penta-BDE

Lichen

Moss

Fig. 2. Percent distribution of PBDE homologs in the commercial penta-BDE formulation compared to lichens and mosses collected along the shore of Admiralty Bay, King George Island, Antarctica. 1592 G.T. Yogui, J.L. Sericano / Chemosphere 73 (2008) 1589–1593of magnitude higher than the PBDE contamination in this study ( Bacci et al., 1986 ).PBDEs were detected in all lichen and moss samples. These species absorb PBDEs directly from the atmosphere as they lack rootlike structures. Long-range atmospheric transport is believed to bethe major source of PBDEs to King George Island since contamination is not statistically different at sites close to and distant fromhuman facilities. Mosses evidenced contamination levels significantly higher than lichens. This is likely associated with the primary process responsible for PBDEs uptake from the atmosphere which may be governed by a number of chemical, environmentaland plant properties. Further studies are needed to better understand the role of Antarctic vegetation as a sink for anthropogenic organic pollutants.

Acknowledgements

The authors are thankful to Dr. Rosalinda Montone for the opportunity to participate in the Antarctic expeditions, and Dr.Chuck Kennicutt, Dr. Terry Wade and Dr. Miguel Mora for comments on this manuscript. Mr. Filipe Victoria and Mr. Adriano Spielmann deserve credit for the identification of plant species.Field trips to collect samples in Antarctica were financially supported by the Brazilian Antarctic Program (CNPq Project Number 55.0348/02-6; Environmental Management of Admiralty Bay, KingGeorge Island, Antarctica: POPs and sewage pollution) and the College of Geosciences at Texas A&M University (through the Pipes Endowed Fellowship). G. T. Yogui was funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Ministry of Education, Brazil.

Appendix A. Supplementary material

Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.chemosphere.2008.08.035

.

References

Ahn, M.Y., Filley, T.R., Jafvert, C.T., Nies, L., Hua, I., Bezares-Cruz, J., 2006. Photodegradation of decabromodiphenyl ether adsorbed onto clay minerals, metal oxides, and sediment. Environ. Sci. Technol. 40, 215–220. AMAP, 2004. Persistent Toxic Substances, Food Security and Indigenous Peoples of the Russian North. Final Report. Arctic Monitoring and Assessment Programme, Oslo, p. 192. Bacci, E., Calamari, D., Gaggi, C., Fanelli, R., Focardi, S., Morosini, M., 1986. Chlorinated hydrocarbons in lichen and moss samples from the Antarctic Peninsula. Chemosphere 15, 747–754. Bezares-Cruz, J., Jafvert, C.T., Hua, I., 2004. Solar photodecomposition of decabromodiphenyl ether: products and quantum yield. Environ. Sci. Technol. 38, 4149–4156. Buckley, E.H., 1982. Accumulation of airborne polychlorinated biphenyls in foliage. Science 216, 520–522. Corsolini, S., Covaci, A., Ademollo, N., Focardi, S., Schepens, P., 2006. Occurrence of organochlorine pesticides (OCPs) and their enantiomeric signatures, and concentrations of polybrominated diphenyl ethers (PBDEs) in the Adelie penguin food web, Antarctica. Environ. Pollut. 140, 371–382. de Boer, J., Wester, P.G., Klammer, H.J.C., Lewis, W.E., Boon, J.P., 1998. Do flame retardants threaten ocean life? Nature 394, 28–29. de Wit, C.A., 2002. An overview of brominated flame retardants in the environment. Chemosphere 46, 583–624. de Wit, C.A., Alaee, M., Muir, D.C.G., 2006. Levels and trends of brominated flame retardants in the Arctic. Chemosphere 64, 209–233. Dytham, C., 2003. Choosing and Using Statistics: A Biologist’s Guide. Blackwell Publishing, Oxford. EPA, 2003. Draft Method 1614. Brominated Diphenyl Ethers in Water, Soil, Sediment, and Tissue by HRGC/HRMS. US Environmental Protection Agency, Washington, p. 83. Eriksson, J., Green, N., Marsh, G., Bergman, A., 2004. Photochemical decomposition of 15 polybrominated diphenyl ether congeners in methanol/water. Environ. Sci. Technol. 38, 3119–3125. Godoy, J.M., Schuch, L.A., Nordemann, D.J.R., Reis, V.R.G., Ramalho, M., Recio, J.C., Brito, R.R.A., Olech, M.A., 1998. 137Cs, 226,228Ra, 210Pb and 40K concentrations in antarctic soil, sediment and selected moss and lichen samples. J. Environ. Radioactiv. 41, 33–45. Hale, R.C., Kim, S.L., Harvey, E., La Guardia, M.J., Mainor, T.M., Bush, E.O., Jacobs, E.M., 2008. Antarctic research bases: local sources of polybrominated diphenlyl ether (PBDE) flame retardants. Environ. Sci. Technol. 42, 1452–1457. Keum, Y.S., Li, Q.X., 2005. Reductive debromination of polybrominated diphenyl ethers by zerovalent iron. Environ. Sci. Technol. 39, 2280–2286. La Guardia, M.J., Hale, R.C., Harvey, E., 2006. Detailed polybrominated diphenyl ether (PBDE) congener composition of the widely used penta-, octa-, and deca-PBDE technical flame-retardant mixtures. Environ. Sci. Technol. 40, 6247–6254. Lauenstein, G.G., Cantillo, A.Y. (Eds.), 1998. Sampling and Analytical Methods of the National Status and Trends Program Mussel Watch Project: 1993–1996 Update. US Department of Commerce, Silver Spring. Mietelski, J.W., Gaca, P., Olech, M.A., 2000. Radioactive contamination of lichens and mosses collected in South Shetlands and Antarctic Peninsula. J. Radioanal. Nucl. Chem 245, 527–537. Montone, R.C., Taniguchi, S., Boian, C., Weber, R.R., 2005. PCBs and chlorinated pesticides (DDTs, HCHs and HCB) in the atmosphere of the southwest Atlantic and Antarctic oceans. Mar. Pollut. Bull. 50, 778–782. Montone, R.C., Taniguchi, S., Weber, R.R., 2003. PCBs in the atmosphere of King George Island, Antarctica. Sci. Total Environ. 308, 167–173. Morosini, M., Schreitmuller, J., Reuter, U., Ballschmiter, K., 1993. Correlation between C-6/C-14 chlorinated hydrocarbons levels in the vegetation and in the boundary layer of the troposphere. Environ. Sci. Technol. 27, 1517–1523. Olech, M., Kwiatek, W.M., Dutkiewicz, E.M., 1998. Lead pollution in the Antarctic region. X-ray Spectrom. 27, 232–235. Osyczka, P., Dutkiewicz, E.M., Olech, M., 2007. Trace elements concentrations in selected moss and lichen species collected within Antarctic research stations. Pol. J. Ecol. 55, 39–48. Ott, R.L., Longnecker, M., 2001. An Introduction to Statistical Methods and Data Analysis. Duxbury, Pacific Grove. Øvstedal, D.O., Lewis-Smith, R.I., 2001. Lichens of Antarctica and South Georgia: A Guide to Their Identification and Ecology. Cambridge University Press, Cambridge. Peat, H.J., Clarke, A., Convey, P., 2007. Diversity and biogeography of the Antarctic flora. J. Biogeogr. 34, 132–146. Poblet, A., Andrade, S., Scagliola, M., Vodopivez, C., Curtosi, A., Pucci, A., Marcovecchio, J., 1997. The use of epilithic Antarctic lichens ( Usnea aurantiacoatra and U. antartica ) to determine deposition patterns of heavy metals in the Shetland Islands, Antarctica. Sci. Total Environ. 207, 187–194. Rakusa-Suszczewski, S., 1980. Environmental conditions and functioning of Admiralty Bay (South Shetland Islands) as part of the near shore Antarctic ecosystem. Pol. Polar Res. 1, 11–27. Rakusa-Suszczewski, S., 1995. The hydrography of Admiralty Bay and its inlets, coves and lagoons (King George Island, Antarctica). Pol. Polar Res. 16, 61– 70. Rakusa-Suszczewski, S., Battke, Z., Cisak, J., 1993. Morphometry of the Admiralty Bay shores and basin. In: Rakusa-Suszczewski, S. (Ed.), The Maritime Antarctic Coastal Ecosystem of Admiralty Bay. Polish Academy of Sciences, Warsaw, pp. 27–30. Rayne, S., Wan, P., Ikonomou, M., 2006. Photochemistry of a major commercial polybrominated diphenyl ether flame retardant congener: 2, 2 0 , 4, 40 , 5, 5 0

- hexabromodiphenyl ether (BDE153). Environ. Int. 32, 575–585. Schuller, P., Bunzl, K., Voigt, G., Handl, J., Ellies, A., Castillo, A., 2002. Fallout radiocesium in an Antarctic region: deposition history, activity densities and vertical transport in soils. Radiat. Environ. Biophys. 41, 295–302. Seymour, F.A., Crittenden, P.D., Wirtz, N., Ovstedal, D.O., Dyer, P.S., Lumbsch, H.T., 2007. Phylogenetic and morphological analysis of Antarctic lichen-forming Usnea species in the group Neuropogon. Antarct. Sci. 19, 71–82. Shaw, A.J., 2001. Biogeographic patterns and cryptic speciation in bryophytes. J. Biogeogr. 28, 253–261. Simonich, S.L., Hites, R.A., 1995. Organic pollutant accumulation in vegetation. Environ. Sci. Technol. 29, 2905–2914. Smith, R.I.L., 1996. Terrestrial and freshwater biotic components of the western Antarctic Peninsula. In: Ross, R.M., Hofmann, E.E., Quentin, L.B. (Eds.), Foundations of Ecological Research West of the Antarctic Peninsula. American Geophysical Union, Washington, pp. 15–59. Walker, F.J., 1985. The lichen genus Usnea subgenus Neuropogon. B. Brit. Mus. – Nat. Hist Botany 13, 1–130. Wania, F., Mackay, D., 1993. Global fractionation and cold condensation of low volatility organochlorine compounds in polar regions. Ambio 22, 10–18. Yogui, G.T., 2008. Polybrominated Diphenyl Ether Flame Retardants in the Antarctic Environment. Ph.D. Dissertation, Texas A&M University, College Station. G.T. Yogui, J.L. Sericano / Chemosphere 73 (2008) 1589–1593 1593