Biomagnification of Perfluorinated Compounds in a Remote Terrestrial Food Chain: Lichen-Caribou-Wolf

Transcription

1 Supporting Information for Biomagnification of Perfluorinated Compounds in a Remote Terrestrial Food Chain: Lichen-Caribou-Wolf Claudia E. Müller,, Amila O. De Silva, Jeff Small, Mary Williamson, Xiaowa Wang, Adam Morris, Sharon Katz, Mary Gamberg #, Derek C.G. Muir Laboratory for Analytical Chemistry, Empa, Dübendorf, Switzerland Institute for Chemical- and Bioengineering, ETH Zürich, Zürich, Switzerland Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington, ON Canada School of Environmental Sciences, University of Guelph, Guelph, ON Canada Aurora Research Institute, Inuvik, NT Canada # Gamberg Consulting, Whitehorse, YK Canada This file includes: Materials and Methods Supporting Figures S1-6 Supporting Tables S1-14 Supplemental References Total Pages: 20 S1

2 Materials and Methods Chemicals: Standards were obtained from Wellington Laboratories (Guelph, ON). The entire list is given Table SI 1. Methanol (optima grade), acetonitrile (gradient grade) and water (HPLC grade) were obtained from VWR International (Mississauga, ON, Canada). Acetic acid was from Fisher Scientific (Ottawa, ON, Canada) and ammonium acetate was purchased from Sigma Aldrich (Oakville, ON, Canada). Nitrogen gas (Ultra High Purity) was obtained from Air Liquide (Burlington, ON, Canada). Samples: Caribou (rangifer tarandus groenlandicus) of the Porcupine herd in Yukon and the Bathurst herd in Northwest Territories (see map in Figure S1) were hunted in October-December 2007 and 2008, respectively. Tissues acquired from caribou consisted of muscle, kidney and liver. Wolf (canis lupus) samples were obtained from animals hunted in the same regions as the caribou, but due to logistical reasons they were not collected at the same time. Wolf samples were obtained from the Bathurst region in February-March 2007 and in February-March 2010 from the Yukon. Caribou and wolf sampling was done by local hunters and trappers as part of traditional hunting. Most individuals were sampled both for liver and muscle. The exact locations of all samples and sampling times are shown in Table S2. Caribou and wolf muscle, liver and kidney samples were first stored in clean plastic bags and after subsampling in polypropylene bottles at -20 C. Vegetation samples were collected within the two caribou herd ranges. They consisted of (cladonia mitis/rangiferina and flavocetraria nivalis/cucullata), cottongrass (eriophorum vaginatum), aquatic sedge (carex aquatilis) and willow (salix pulchra) leaf samples from Yukon (taken in summer 2008) and, cottongrass, willow leaf, moss (rythidium rugosum) and mushroom samples from Northwest Territories (collected in summer 2009) at different locations. Vegetation samples were stored in sealed plastic bags at - 20 C until freeze drying. After drying, the willow and samples were crushed in the closed bag to prepare for extraction. The branches of the willow samples were not included in the analysis. Grass samples were cut into small pieces with scissors. Sample preparation was conducted in a clean room (HEPA and Carbon filtered air) to avoid any contamination. Care was taken to avoid contamination with soil. Methods: Plant matter (1 g) was accurately weighed into a 50 ml polypropylene centrifuge tube and 10 µl of internal standard mixture was added (see Table S1). After 30 min of equilibration, 10 ml of methanol were added and the tube was shaken on a mechanical shaker at 350 rpm for 5 minutes. The tube was centrifuged at 4000 rpm for 5 min and decanted into a clean polypropylene centrifuge tube. This process was repeated twice more with 5 ml methanol, combining the extracts. The 20 ml extract was concentrated to 1 ml with ultrahigh purity nitrogen. Extracts were subjected to further clean up using 100 mg SampliQ Carbon solid phase extraction (SPE) cartridge (Agilent Technologies, Santa Clara, CA). Cartridges were conditioned S2

3 with 5 ml methanol, followed by 2 ml 1.5% acetic acid in methanol. The extract was loaded onto the SPE at a 1 ml/min under gravity or low vacuum, while collecting the eluate. An additional 1 ml of methanol was passed through the cartridge. The eluate was then taken to dryness using N 2 and reconstituted in 1 ml of 50:50 methanol/water. The liver, kidney and muscle samples were analyzed according to a modified method from Powley et al. 1 In summary, the sample was roughly homogenized and 1 g of sample was then further homogenized with a hand homogenizer in 8 ml of methanol. The sample was aliquoted into 2 ml subsamples for liver and 4 ml subsamples for muscle samples. 10 µl of internal standard mixture was added to every sample. The samples were then extracted twice with 2 ml of methanol. The combined extracts were evaporated under a steady flow of nitrogen to dryness and reconstituted with 1 ml of methanol. The extracts were cleaned with a SampliQ Carbon SPE in the same way as for plant samples. Method blanks were performed in the same way as the samples. Methanol was taken as the surrogate for plant or animal tissue. In the course of this study it was shown that taurodeoxchloic acid and other isoforms interfere with PFOS quantification ( both and transitions) in some animal and human tissues. 2 Method intercomparison also showed that extraction with acetonitrile rather than methanol reduces these interferences. 3 It was therefore decided to change the method for caribou and wolf tissues later in the project from methanol to acetonitrile extraction. Spike and recovery experiments for caribou and wolf (see Table S3) did however not show any difference between the two methods. It was therefore decided to use the results from both methods. Stable isotope analysis: Stable isotope analysis for carbon and nitrogen was conducted for vegetation, caribou and wolf samples mg of dried sample was used for 15 N and 13 C determination with continuous flow isotope ratio mass spectrometry. Samples were standardized against atmospheric nitrogen or Canyon Diablo PeeDee Belemnite (National Institute of Standards and Technology, Gaithersburg, MD, USA) using the equation (1), where R is 15 N/ 14 N or 13 C/ 12 C ratio. δ 15 Nor δ 13 C (R sample / R 1) 1000 (1) standard Replicate samples had a precision of S3

4 Supporting Figures Alaska Porcupine caribou range Canada Yukon Northwest Territories Snare Rapids Bathurst caribou range Nunavut Figure S1: Map of Canada with the two caribou herd ranges (Porcupine and Bathurst) indicated with circles and the location of rain sampling at Snare Rapids indicated with an arrow. (Cladonia) Figure S2: 15 N and 13 C of the investigated species with their corresponding standard deviation for the two caribou herd ranges. The white dots represent the combined food source calculated by the IsoSource Model 4. S4

5 Figure S3: PFCAs and PFOS concentrations for the investigated tissues of caribou and wolf for both herds shown in a logarithmic scale. Additionally, the contribution of the tissues to the PFCAs and PFOS body burden is shown for both species. S5

6 Figure S4: Comparison of PFCA and PFO concentrations between the Porcupine and Bathurst food web. Shown is the average concentration ± standard error. Bathurst concentration marked with a star are significantly higher (p < 0.05) than the corresponding Porcupine concentration. All p values are listed in the table. S6

7 Figure S5: TMF calculations for the Porcupine caribou herd range. The bold TMF and the continuous line show the regression with only, the dashed line shows the regression with all vegetation samples shown here. S7

8 Figure S6: TMF calculations for the Bathurst caribou herd range. The bold TMF and the continuous line show the regression with only, the dashed line shows the regression with all vegetation samples shown here. S8

9 Supporting Tables Table S1: List of target analytes and mass-labeled standards with their MS/MS transitions. Chemical Name Abbreviation Quantifier transition Qualifier transition Target analytes Perflurorohexanoic acid PFHxA Perfluroheptanoic acid PFHpA Perfluotooctanoic acid PFOA Perfluorononanoic acid PFNA Perfluorodecanoic acid PFDA Perfluoroundecanoic acid PFUnA Perfluorododecanoic acid PFDoA Perfluorotridecanoic acid PFTrA Perfluorotetradecanoic acid PFTeA Perfluorohexane sulfonate PFHxS Perfluorooctane sulfonate PFOS Mass labeled internal standards C 4 -Perfluorooctanoic acid a 13 C 4 PFOA C 5 -Perfluorononanoic acid b 13 C 5 PFNA C 2 -Perfluorodecanoic acid c 13 C 2 PFDA C 2 -Perfluorododecanoic acid d 13 C 2 PFDoA C 4 -Perfluorooctane sulfonate e 13 C 4 PFOS a used to quantify PFHxA, PFHpA and PFOA; b used to quantify PFNA; c used to quantify PFDA and PFUnA; d used to quantify PFDoA, PFTrA and PFTeA; e used to quantify PFHxS and PFOS. S9

10 Table S2: Location, sampling date and type of samples with the stable isotope measurements (± SD) and the nitrogen content (± SD). common name Latin name sample type n collection date δ13c±sd [ ] δ15n±sd [ ] N content [%] Porcupine herd food web Cladonia mitis/rangiferina whole organisms 8 June 24 - July ± ± ± 0.06 Flavocetratia nivalis/cucullata whole organisms 10 June 24 - July ± ± ± 0.03 willow Salix pulchra leaves 8 cotton grass water sedge caribou Eriophorum vaginatum Carex pulchra Rangifer tarandus groenlandicus grass without roots grass without roots liver, muscle, kidney June 24 - July June 24 - July June 24 - July Oct- December ± ± ± ± ± ± ± ± ± ± ± ± 0.50 wolf canis lupus liver, muscle 6 Feb-Mar ± ± ± 0.48 Bathurst herd food web Cladonia mitis/rangiferina whole organisms 9 August ± ± ± 0.17 willow Salix pulchra leaves 3 cotton grass moss Eriophorum vaginatum Rhytidium rugosum grass without roots whole organisms 6 3 August 2009 August 2009 August ± ± ± ± ± ± ± ± ± 0.17 mushroom not determinable whole organisms 3 August ± ± ± 0.62 caribou Rangifer tarandus groenlandicus liver, muscle 10 Oct- December ± ± ± 0.37 wolf canis lupus liver, muscle 10 Feb-Mar ± ± ± 0.35 S10

11 Table S3: Method recoveries for all species analyzed. Recoveries were determined with spike and recovery experiments. Recovery [%] PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS Extraction solvent (n=2) methanol plants (n=4) 26±18 35±20 42±19 44±24 44±20 46±21 43±27 methanol mushroom (n=2) methanol liver caribou (n=1) acetonitrile muscle wolf Porcupine (n=1) liver wolf Porcupine (n=1) liver wolf Bathurst (n=2) muscle caribou (n=5) acetonitrile acetonitrile methanol 77±7 94±8 83±3 94±7 82±7 66±6 76±5 methanol Table S4: Method detection limit for all samples analyzed. MDL / (IDL ) [ng/g] plants and Porcupine plants and Bathurst PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS (0.004) (0.004) (0.004) (0.004) (0.004) (0.004) (0.003) (0.004) (0.004) (0.004) (0.004) (0.004) (0.004) (0.003) mushroom (0.005) (0.005) (0.005) (0.005) (0.005) (0.005) (0.004) caribou muscle (0.010) (0.01) (0.010) (0.01) (0.010) (0.01) (0.01) caribou liver Porcupine a (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) (0.5) caribou liver Bathurst (0.01) (0.01) (0.01) (0.01) (0.01) (0.01) 0.44 (0.01) wolf Porcupine (0.01) (0.01) (0.01) (0.01) (0.01) (0.01) (0.01) wolf Bathurst (0.01) (0.01) (0.01) (0.01) (0.01) (0.01) (0.01) MDL Method detection limit: 3 standard deviation of blank, if blank is below instrumental detection limit (IDL), then MDL = IDL IDL: 10 x standard deviation of noise a caribou liver samples w ere measured w ith an older, less sensitive instrument (API 2000 triple quadrupole MS, Applied Biosystems) S11

12 Figure S5: Average method blank concentrations for all species. Average Blank [ng/g] PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS plants and Porcupine (n=3) plants, and mushroom Bathurst (n=5) ND caribou muscle (n=5) caribou liver Porcupine (n=2) caribou liver Bathurst (n=4) wolf muscle/liver Porcupine (n=2) wolf muscle/liver Bathurst (n=2) ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND a Bathurst and Porcupine; ND not detected (< instrumental detection limit) Table S6: Tissue fractions for caribou and wolf used for whole body estimation. caribou a fraction fraction without bones fraction wolf b fraction without bones kidney 0.2% 0.2% 0.7% 0.7% liver 1.1% 1.2% 3.2% 3.5% muscle 61.4% 67.5% 51.1% 55.9% lungs 1.4% c 1.5% 1.4% 1.5% blood 7.7% c 8.5% 8.0% c 8.8% bones 9% c 8.7% carcass 18.2% 20.0% 27.0% 29.6% a organ weights determined for Porcupine caribou; b organ weights determined for one wolf from Yukon. S12

13 Table S7: Overview on all concentrations measured for all species: Sampling size, range and average concentration (ng/g wet weight) for every PFC with frequency of detection in percentage. Sum PFCA concentrations are shown as average value ± SE. Porcupine concentration [ng/g ww] sample n PFOA PFNA PFDA PFUnA PFDoA PFTrA S PFCAs PFOS (Flavocetraria) (Cladonia) 10 8 < < < < < < < ± 0.07 (0.02, 50%) (0.06, 60%) (0.025, 30%) (0.038, 80%) (0.016, 60%) (0.014, 20%) (0.014, 40%) < < < < < < < ± 0.06 (0.02, 80%) (0.08, 80%) (0.02, 50%) (0.05, 100%) (0.01, 70%) (0.02, 90%) (0.01, 50%) willow 7 cottongrass 10 water sedge 3 < < < < < <0.004 < ± 0.14 (0.191, 71%) (0.056, 71%) (0.010, 14%) (0.003, 29%) (0.003, 14%) (0%) (0.062, 43%) < <0.004 < < < <0.004 < ± 0.02 (0.013, 30%) (0%) (0.003, 10%) (0.003, 40%) (0.005, 30%) (0%) (0.002, 10%) < <0.004 <0.004 <0.004 < <0.004 < ± 0.01 (0.004, 33%) (0%) (0%) (0%) (0.007, 33%) (0%) (0%) caribou muscle 7 < < <0.01 < < ± 0.04 (0.02, 71%) (0.06, 100%) (0.03, 86%) (0.07, 100%) (0%) (0.03, 86%) (0.03, 29%) caribou liver 10 caribou kidney 10 wolf muscle 6 wolf liver 6 < <0.5 < ± 0.44 (0%) (2.22, 100%) (1.90, 100%) (1.72, 100%) (0%) (0%) (0.67, 100%) < < < <0.01 <0.01 < ± 0.03 (0%) (0.10, 100%) (0.02, 90%) (0.02, 90%) (0%) (0%) (0.02, 90%) < ± 0.11 (0.08, 100%) (0.44, 100%) (0.11, 100%) (0.15, 100%) (0.02, 100%) (0.01, 25%) (0.13, 100%) ± 1.7 (0.23, 100%) (4.68, 100%) (1.98, 100%) (2.47, 100%) (0.42, 100%) (0.35, 100%) (1.41, 100%) Some values are < MDL, but are still shown and included in all calculations to avoid censoring the data, see Borgå et al. 9 S13

14 Table S7 continued Bathurst concentration [ng/g ww] sample n PFOA PFNA PFDA PFUnA PFDoA PFTrA S PFCAs PFOS (Cladonia) 9 < < < < ± 0.07 (0%) (0.10, 100%) (0.07, 89%) (0.04, 100%) (0.01, 78%) (0.01, 78%) (0.02, 100%) willow 3 cottongrass 3 moss 5 mushroom < ± 0.01 (0.034, 100%) (0.021, 100%) (0.005, 100%) (0.013, 100%) (0%) (0.008, 100%) (0.018, 100%) < < < ± 0.04 (0.05, 100%) (0.04, 100%) (0.005, 67%) (0.02, 100%) (0.002, 33%) (0.01, 100%) (0.01, 66%) < < < ± 0.04 (0.02, 100%) (0.06, 100%) (0.01, 80%) (0.02, 80%) (0.004, 80%) (0.01, 100%) (0.01, 100%) < < <0.005 < < ± 0.08 (0.19, 67%) (0.01, 67%) (0%) (0.01, 67%) (0.02, 100%) (22%) (0.04, 100%) caribou muscle 9 < < < ± 0.06 (0.02, 78%) (0.09, 100%) (0.07, 100%) (0.18, 100%) (0.03, 33%) (0.05, 100%) (0.08, 89%) caribou liver 7 wolf muscle 10 wolf liver ± 0.89 (0.11, 100%) (3.15, 100%) (2.21, 100%) (3.21, 100%) (0.66, 100%) (0.49, 100%) (2.18, 100%) < < < < ± 0.47 (0.06, 80%) (1.14, 100%) (0.21, 90%) (0.57, 100%) (0.04, 30%) (0.26, 100%) (0.14, 100%) < ± 2.9 (0.10, 80%) (7.38, 100%) (3.15, 100%) (6.40, 100%) (0.72, 100%) (0.55, 100%) (1.69, 100%) Some values are < MDL but are still shown and included in all calculations to avoid censoring the data, see Borgå et al. 9 S14

15 Table S8: Correlation analysis of age and concentration for those caribou individual with known age and gender. The coefficients of variation R 2 and p-values are shown per herd and tissue. concentration [ng/g ww] individual age gender PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS Porcupine caribou muscle 1 3 M <MDL M <MDL F <MDL M <MDL M <MDL M <MDL Porcupine caribou R p-value M <MDL <MDL <MDL M <MDL <MDL <MDL F <MDL <MDL <MDL M <MDL <MDL <MDL M <MDL <MDL <MDL M <MDL <MDL <MDL Bathurst caribou liver R p-value muscle 2 6 M <MDL M <MDL F <MDL M <MDL F <MDL F Bathurst caribou R p-value liver 1 6 M M M F M F R p-value S15

16 Table S9: Correlation analysis of age and concentration for those wolf individual with known age and gender. The coefficients of variation R 2 and p-values are shown for both tissues. concentration [ng/g ww] individual age gender PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS Porcupine wolves muscle 2 2 M <MDL M <MDL F <MDL M F <MDL M <MDL Porcupine wolves R p-value liver 1 2 M M F M F M R p-value Table S10: Average moisture content of vegetation species. Porcupine Bathurst species moisture content [%] species moisture content [%] (Flavocetraria) 23 (Cladonia) 25 (Cladonia) 30 willow 41 willow 44 cottongrass 45 cottongrass 47 moss 79 water sedge 45 mushroom 71 S16

17 Table S11: Selected literature concentrations of Arctic animal and abiotic samples. sample type Ref. PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS unit seal (liver) polar bear (liver) rain (Snare Rapids, NT) Arctic ice core (Meighen) Arctic Lake (Resolute) Arctic particulate air ng/g ng/g ng/l NA NA pg/l NA 45.0 ng/l ND pg/m 3 NA not analyzed; ND not detected Table S12: Food source calculations for the two caribou herds based on the IsoSource Model 4. Porcupine species latin name Bathurst food source contribution ± SD species latin name food source contribution ± SD Cladonia mitis/rangiferina 2% ± 2% Cladonia mitis/rangiferina 36% ± 2% Flavocetratia nivalis/cucullata 36% ± 2% willow Salix pulchra 1% ± 1% willow Salix pulchra 1% ± 1% cotton grass Eriophorum vaginatum 28% ± 6% cotton grass Eriophorum vaginatum 59% ± 4% moss Rhytidium rugosum 1% ± 1% water sedge Carex pulchra 1% ± 1% mushroom 34% ± 6% S17

18 Table S13: BMFs and TMFs for vegetation-caribou-wolf and -caribou-wolf food chain for both study areas. type food chain PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS biomagnification factors (BMFs) caribou muscle/ caribou muscle/vegetation caribou liver/ caribou liver/ vegetation wolf muscle/ caribou muscle wolf liver/ caribou muscle wolf liver/ caribou liver caribou wb/ caribou wb/ vegetation wolf wb/ caribou wb Porcupine 0.9 ± ± ± ± ± ± ± 1.8 Bathurst ± ± ± ± ± ± 1.0 Porcupine 1.2 ± ± ± ± ± ± ± 3.7 Bathurst 0.3 ± ± ± ± ± ± ± 0.9 Porcupine - 40 ± ± ± ± ± ± 19 Bathurst 11 ± ± ± ± ± ± ± 18 Porcupine ± ± ± ± 46 Bathurst 1.4 ± ± ± ± ± ± ± 18 Porcupine 3.8 ± ± ± ± ± 3.8 Bathurst 2.6 ± ± ± ± ± ± ± 0.5 Porcupine 10.2 ± ± ± ± ± 43 Bathurst 4.2 ± ± ± ± ± ± ± 5.8 Porcupine ± ± ± ± 0.6 Bathurst 0.9 ± ± ± ± ± ± ± 0.1 Porcupine 1.4 ± ± ± ± ± ± ± 2.3 Bathurst 2.6 ± ± ± ± ± ± ± 1.6 Porcupine 1.8 ± ± ± ± ± ± ± 4.9 Bathurst 0.3 ± ± ± ± ± ± ± 1.6 Porcupine 2.4 ± ± ± ± ± ± ± 0.0 Bathurst 2.1 ± ± ± ± ± ± ± 0.2 wb: whole body; BMF± standard error; values not shown for single tissue BMFs with concentrations <MDL S18

19 Table S13 continued: type food chain PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS trophic magnification factors (TMFs) wolf liver/ caribou liver/ Porcupine 2.37 ( ) 6.67 ( ) 7.08 ( ) 6.58 ( ) 4.06 ( ) 3.74 ( ) 6.70 ( ) Bathurst 2.17 ( ) 4.45 ( ) 5.14 ( ) 6.13 ( ) 5.24 ( ) 4.18 ( ) 5.20 ( ) wolf wb/ caribou wb/ Porcupine 1.32 ( ) 2.68 ( ) 2.61 ( ) 2.54 ( ) 1.41 ( ) 1.43 ( ) 2.65 ( ) Bathurst 1.31 ( ) 2.15 ( ) 2.30 ( ) 2.80 ( ) 2.19 ( ) 1.97 ( ) 2.42 ( ) wolf liver/ caribou liver/ vegetation Porcupine 1.84 ( ) 4.38 ( ) 5.50 ( ) 5.23 ( ) 3.46 ( ) 3.21 ( ) 5.11 ( ) Bathurst 1.92 ( ) 3.36 ( ) 4.35 ( ) 5.47 ( ) 4.05 ( ) 3.28 ( ) 4.27 ( ) wolf wb/ caribou wb/ vegetation Porcupine 1.10 ( ) 1.95 ( ) 2.27 ( ) 2.25 ( ) 1.35 ( ) 1.37 ( ) 2.24 ( ) Bathurst 1.28 ( ) 1.88 ( ) 2.29 ( ) 2.93 ( ) 2.02 ( ) 1.80 ( ) 2.31 ( ) wb: whole body; TMF (95% confidence interval) S19

20 Table S14: Trophic magnification factor (TMF) results and their 95% confidence intervals, the linear regression with correlation coefficient and significance value for the two TMF calculation basis. p- TMF 95 % CI ln(conc)=m TL+b R 2 value TMF 95 % CI ln(conc)=m TL+b R 2 p-value -caribou-wolf n = 27 Porcupine, n = 21 Bathurst veg-caribou-wolf n = 37 Porcupine, n = 34 Bathurst PFOA PFNA PFDA PFUnA PFDoA PFTrA PFOS Porcupine 1.32 ( ) 0.28(TL) ( ) 0.09(TL) Bathurst 1.31 ( ) 0.27(TL) ( ) 0.24(TL) Porcupine 2.68 ( ) 0.98(TL) < ( ) 0.66(TL) Bathurst 2.15 ( ) 0.77(TL) < ( ) 0.63(TL) Porcupine 2.61 ( ) 0.96(TL) < ( ) 0.82(TL) < Bathurst 2.30 ( ) 0.83(TL) < ( ) 0.83(TL) <0.001 Porcupine 2.54 ( ) 0.93(TL) < ( ) 0.81(TL) <0.001 Bathurst 2.80 ( ) 1.03(TL) < ( ) 1.07(TL) < Porcupine 1.41 ( ) 0.34(TL) < ( ) 0.30(TL) <0.001 Bathurst 2.19 ( ) 0.78(TL) < ( ) 0.70(TL) < Porcupine 1.43 ( ) 0.35(TL) < ( ) 0.31(TL) Bathurst 1.97 ( ) 0.68(TL) < ( ) 0.59(TL) < Porcupine 2.65 ( ) 0.97(TL) < ( ) 0.81(TL) < Bathurst 2.42 ( ) 0.88(TL) < ( ) 0.84(TL) < TL: trophic level S20

21 Supplemental References: (1) Powley, C. R.; George, S. W.; Ryan, T. W.; Buck, R. C., Matrix effect-free analytical methods for determination of perfluorinated carboxylic acids in environmental matrixes. Anal. Chem. 2005, 77, (19), (2) Benskin, J. P.; Bataineh, M.; Martin, J. W., Simultaneous characterization of perfluoroalkyl carboxylate, sulfonate, and sulfonamide isomers by liquid chromatography-tandem mass spectrometry. Anal. Chem. 2007, 79, (17), (3) Keller, J. M.; Calafat, A. M.; Kato, K.; Ellefson, M. E.; Reagen, W. K.; Strynar, M.; O'Connell, S.; Butt, C. M.; Mabury, S. A.; Small, J.; Muir, D. C. G.; Leigh, S. D.; Schantz, M. M., Determination of perfluorinated alkyl acid concentrations in human serum and milk standard reference materials. Anal. Bioanal. Chem. 2010, 397, (2), (4) Phillips, D. L.; Gregg, J. W., Source partitioning using stable isotopes: Coping with too many sources. Oecologia 2003, 136, (2), (5) Martin, J. W.; Smithwick, M. M.; Braune, B. M.; Hoekstra, P. F.; Muir, D. C. G.; Mabury, S. A., Identification of long-chain perfluorinated acids in biota from the Canadian Arctic. Environ. Sci. Technol. 2004, 38, (2), (6) Scott, B. F.; Spencer, C.; de Silva, A. O.; Muir, D. C. G., PFAs in precipitation at Snare Rapids NT. Unpublished data. Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington ON. (7) Young, C. J.; Furdui, V. I.; Franklin, J.; Koerner, R. M.; Muir, D. C. G.; Mabury, S. A., Perfluorinated Acids in Arctic Snow: New Evidence for Atmospheric Formation. Environ. Sci. Technol. 2007, 41, (10), (8) Stock, N. L.; Furdui, V. I.; Muir, D. C. G.; Mabury, S. A., Perfluoroalkyl Contaminants in the Canadian Arctic: Evidence of Atmospheric Transport and Local Contamination. Environ. Sci. Technol. 2007, 41, (10), (9) Borgå, K.; Kidd, K.A.; Berglund O.; Conder J.M.; Gobas F.A.P.C.; Kucklick, J.R.; Kay, D.; Malm, O.; Powell, D.E.; Muir, D.C.G. (2011). Trophic Magnification Factors: Impact of Ecology,Ecosystem and Study Design. Environ. Assess. Manag. Accepted for publication S21