Supplementary information. hair as a tracer for dietary and occupational exposure to. mercury

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1 Supplementary information Hg speciation and stable isotope signatures in human hair as a tracer for dietary and occupational exposure to mercury Laure Laffont 1,2,3 *, Jeroen E. Sonke 1,4 *, Laurence Maurice 1,5, Selma Luna Monrroy 6, Jaime Chincheros 6 David Amouroux 7 and Philippe Behra 2,3 1 Observatoire Midi-Pyrénées, Laboratoire de Géosciences Environnement Toulouse, Université Paul Sabatier Toulouse III, 14 avenue Edouard Belin, Toulouse, France. 2 Université de Toulouse; INPT, LCA (Laboratoire de Chimie AgroIndustrielle); ENSIACET, 4, allée Emile Monso, F Toulouse Cedex 4 3 INRA; LCA (Laboratoire de Chimie AgroIndustrielle); F Toulouse Cedex 4 4 CNRS; GET; F Toulouse 5 IRD; GET; F Toulouse 6 Universidad Mayor de San Andrés (UMSA), Instituto de Ecología, Laboratorio de Calidad Ambiental, Cota Cota Calle 27, La Paz, Bolivia 7 Université de Pau et des Pays de l Adour ; CNRS; LCABIE-IPREM UMR 5254; Hélioparc Pau Pyrénées 2, Avenue Pierre Angot, F PAU Cedex 9 * Corresponding authors: laffont@get.obs-mip.fr and sonke@get.obs-mip.fr 12 pages, 3 Figures and 3 Tables S1

2 Study area The study area is located in the Bolivian Amazon along the Beni River basin (South America; Figure SI-S1). Andean tributaries of the Beni River drain both semi-arid areas of high altitude and areas of tropical humid forest of the piedmont. In the Andean cordillera at the North of Bolivia, native gold is mined along the Yani and upper Tipuani rivers. More downstream alluvial gold has been exploited along the Beni river tributaries Tipuani, Mapiri, Challana and Kaka rivers 1. Gold-miners reject part of Hg to mine tailings yet the majority (75%) of Hg(0) is presumably emitted to the atmosphere via amalgam burning 2. Similar to native gold mining activities, small scale alluvial gold-mining involves sedimentary gold extraction using gravimetric deposition followed by Hg amalgamation. High Hg concentrations in fish are found in the upper Beni river floodplain lakes where a subsidence zone favors the accumulation of Andean sediments 3, 4 and the methylation of Hg 5, 6. Indigenous people and fishermen, living near Rurrenabaque at the edge of the Andean piedmont, are typical populations exposed to large amounts of MMHg via an exclusive fish diet 3, 6. Reagents All labware used for isotopic analyses was cleaned with HNO 3 10% for two days at room temperature or for one day at 393K. A 3% m/v solution of SnCl 2 was prepared with 30 g of SnCl 2.H 2 O (Fisher Scientific) dissolved in 100 ml of bi-distilled HCl and milli-q water (18.2 MΩ cm) to make 1 L of solution. All acids used for digestion were bi-distilled. Multiple certified reference materials (CRM) were used in this study to provide traceability, MMHg spiked hair IAEA-85 and natural hair IAEA-86 (Austria) and University of Michigan Almaden#2 secondary reference material (Um_Alm#2) made from Almaden (Spain) cinnabar, and for isotopic analyses CRM-3133 (HgII), CRM-997 (Tl isotopic standard) from the NIST (USA). S2

3 Preparation of samples Approximately 0.04 g of gold-miners and Europeans hair sample, depending on the Hg T concentration, were digested with a 3 ml mix of HNO 3 and HCl (7/3 v/v) at 393K for 6 h, yielding final Hg T levels, after dilution with Milli-Q water, between 0.5 and 5 ng.g 1 in HNO 3 /HCl between 15 and 25%. The average digestion yield for hair was 97 ± 11% (1SD, n=53). Total Hg concentration analysis The total Hg concentration (Hg T ) was measured by atomic absorption spectroscopy after combustion and gold-trapping with a DMA-80 (Thermo-Fisher - Milestone). A mass of g of hair was weighed into a clean nickel boat before analysis. The temperature programs were: drying at 573K for 10 s and decomposition temperature 1123K for 150 s. The long-term external reproducibility of the measurement was 8.2% (2SD standard deviation, n=10). All samples were determined in duplicate and calibration curve is checked by using IAEA 85 CRM. Hg speciation analyses 30mg of hair samples were mineralized by microwaves heating with 6N TMAH and spiked with enriched standards of 201 MMHg and inorganic 199 Hg recording Monperrus et al. 7. Method was validated in human hair with IAEA-086 CRM (recommended value [MMHg] = 258±22 ng.g 1 (1SD, n=5); obtained value [MMHg] = 255±13 ng.g 1 (1SD, n=3)). Hg isotopic analyses Total Hg isotopic analyses were performed at the laboratory Géoscience Environnement Toulouse (GET, ex-lmtg, Toulouse; France) by Hg(0) cold-vapor generation coupled with multi-collector inductively coupled plasma mass spectrometer CV-MC-ICPMS (Thermo- Finnigan Neptune). The instrument was interfaced with an Aridus II nebulizer (CETAC) for Tl introduction and a Perkin-Elmer FIAS-400 cold-vapor system for Hg(0) (g) generation. S3

4 Hg(0) (g) and Tl dry aerosols were mixed at the outlet of the cold-vapor generating system and before introduction into the plasma. Five isotopes of Hg were measured simultaneously with two isotopes of Tl, the configuration of Faraday cup was: L3-198 Hg, L2-199 Hg, L1-200 Hg, C Hg, H1-202 Hg, H2-203 Tl and H3-205 Tl. Isotopic ratios 202 Hg/ 198 Hg, 201 Hg/ 198 Hg, 200 Hg/ 198 Hg and 199 Hg/ 198 Hg and deltas were calculated after mass-bias correction applying the exponential law (using a 205 Tl/ 203 Tl ratio of ) and with bracketing standard as follows: x δ /198 = ( x ( Hg/ x 198 Hg/ Hg sample x Hg + Hg/ 198 1) *1000 Hg ) / 2 2 where the standard 1 is analyzed before the sample and standard 2 after the sample. The reference material NIST 3133 was used as a bracketing standard for total Hg isotopic analyses and was at the same Hg T and acid concentrations as samples. Blank signals were typically below 1% of the samples signal. In this study, mass-independent fractionation is reported in "capital delta" notation as the difference between the measured δ x/198 and the theoretically predicted δ x/198 value using the relationship (45,46): x /198 Hg =δ Hg β *δ x / / 198 Where β is the equilibrium mass-dependent fractionation factor. Hg Secondary reference material UM-Almaden#2 (analyzed at ng.g 1 [Hg T ] levels) yielded values of 0.48 ± 0.16 for δ 202 Hg, 0.01 ± 0.07 for 199 Hg and 0.03 ± 0.08 for 201 Hg (2SD for n=54, Table SI-S1) in agreement with published values 8. In addition, external uncertainties (2SD) for CRM digest replicates of IAEA 86 (n=3) and IAEA 85 (n=6) were 0.19 and 0.15 for δ 202 Hg, 0.23 and 0.03 for 199 Hg, 0.13 and 0.06 for 201 Hg, respectively. MC-ICPMS measurements on replicate digests were completed for selected samples and the 2SD uncertainty of replicates analyses was used when it was greater than the 2SD external reproducibility on UM-Almaden#2. S4

5 S5

6 Figure SI-S1. Study area and location of hair sampling points of gold miners in the Bolivian Amazon basin. S6

7 Figure SI-S2. Anomaly 199 Hg plotted as a function of 201 Hg for hair samples. Error bars represent external reproducibility (2SD). S7

8 calculated inorganic Hg (ng.ḡ 1 ) a y = 1.1x + 37 R = measured inorganic Hg (ng.g -1 ) calculated total MMHg (ng.ḡ 1 ) b y = 0.7x + 75 R = measured MMHg (ng.g -1 ) Figure SI-S3. Comparison between modeled and measured hair Hg speciation. A Hg stable isotope mass balance was used to calculated two MMHg sources and one inorganic Hg source. Closed symbols represent samples retained for the shown regression line. Open symbols reflect outliers that have Hg calculated speciation fractions that are <0 or >1. See main text for details. S8

9 Table SI-S1: Overview of total Hg concentration (ng.g -1 dry mass), age (year) of people and Hg isotopic analysis ( ). Samples Total [Hg] ng.g -1 %MMHg 2SD MMHg% Age (years) n δ 199 Hg 2SD δ 200 Hg 2SD δ 201 Hg 2SD δ 202 Hg 2SD 199 Hg 2SD 200 Hg 2SD 201 Hg 2SD Liquid Hg(0) used by gold-miners B G G Hg(0) vapor and Hg(0) deposit in gold-shop Trap Soil Vegetation Native gold-miner hair (Yani) FY FY FY FY FY Alluvial gold-miner hair 0.21 Tomachi T T Suraqui SU SU SU SU SU SU SU SU SU SU San Juanito SJ SJ SJ SJ SJ SJ SJ SJ Huacahuilo HU HU European hair Toulouse EU EU EU EU EU EU EU EU EU EU EU S9

10 Table SI-S2: Hg isotopic signatures of liquid Hg(0) from literature and this study Bibliography Nature δ 199 Hg δ 200 Hg δ 201 Hg δ 202 Hg 199 Hg 200 Hg 201 H Bergquist and Blum 2007UM-Almaden# This study Bolivia B Bolivia G01- bought in Guanay Bolivia G02 - recovered after amalgamation NIST NIST Estrade et al Commercial liquid Hg(0) from Rhone-Alpes Technolog Sonke et a l Commercial liquid Hg(0) from Alfa Aesar S10

11 Table SI-S3: Model-estimated concentrations of inorganic Hg, MMHg B from Bolivian fresh water fish and MMHg M from marine fish, in Bolivian gold-miner and native people hair and European hair. Samples [MMHg B ] [MMHg M ] [IHg] ng.g -1 ng.g -1 ng.g -1 Native gold-miner hair (Yani) FY FY FY FY FY Alluvial gold-miner hair Tomachi T T Suraqui SU SU SU SU SU SU SU SU SU SU San Juanito SJ SJ SJ SJ SJ SJ SJ SJ Huacahuilo HU HU European hair Toulouse EU EU EU EU EU EU EU EU EU EU EU Native people hair (Esse Ejjas) Villa Copacabana B B B B B B B Eyiyoquibo 14013a a S11

12 1. Hérail, G.; Fornari, M.; Viscarra, G.; Ruiz, J. A.; Pozzo, L.; Dumont, J.-F. In Les placers d'or de Bolivie : milieux de formation et structure géologique, Gisements alluviaux d'or, La Paz, Wong, H. K. T.; Gauthier, A.; Nriagu, J. O., Dispersion and toxicity of metals from abandoned gold mine tailings at Goldenville, Nova Scotia, Canada. Science of the Total Environment 1999, 228, (1), Maurice-Bourgoin, L.; Quiroga, I.; Chincheros, J.; Courau, P., Mercury distribution in waters and fishes of the upper Madeira rivers and mercury exposure in riparian Amazonian populations. Science of the Total Environment 2000, 260, (1-3), Laffont, L.; Sonke, J. E.; Maurice, L.; Hintelmann, H.; Pouilly, M.; Sanchez Bacarreza, Y.; Perez, T.; Behra, P., Anomalous Mercury Isotopic Compositions of Fish and Human Hair in the Bolivian Amazon. Environmental Science & Technology 2009, 43, (23), Guimarães, J. R. D.; Meili, M.; Hylander, L. D.; Silva, E. d. C.; Roulet, M.; Mauro, J. B. N.; de Lemos, R. A., Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils. Science of the Total Environment 2000, 261, (1-3), Maurice-Bourgoin, L.; Quiroga, I.; Guyot, J.-L.; Malm, O., Mercury pollution in the Upper Beni river, Amazonian basin: Bolivia. Ambio 1999, 28, (4), Monperrus, M.; Gonzalez, P. R.; Amouroux, D.; Alonso, J. I. G.; Donard, O. F. X., Evaluating the potential and limitations of double-spiking species-specific isotope dilution analysis for the accurate quantification of mercury species in different environmental matrices. Analytical and Bioanalytical Chemistry 2008, 390, (2), Bergquist, B. A.; Blum, J. D., Mass-dependent and -independent fractionation of Hg isotopes by photoreduction in aquatic systems. Science 2007, 318, (5849), S12

Application of a selective extraction method. for methylmercury compound specific stable. isotope analysis (MeHg CSIA) in biological.

1 Supplementary information for 2 3 4 5 Application of a selective extraction method for methylmercury compound specific stable isotope analysis (MeHg CSIA) in biological materials 6 7 Jeremy Masbou* a,