Electronic Supplementary Material (ESI) for Environmental Science: Processes & Impacts. This journal is © The Royal Society of Chemistry 2014 Electronic Supplementary Information for Cluster Analysis of Passive Air Sampling Data Based on the Relative Composition of Persistent Organic Pollutants XIANDE LIU,1,* FRANK WANIA2 1 State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; 2 Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4 Table of Content Section 1 Chengdu-WNR (Wolong Natural Reserve), Southwestern China S2 Figure S1 Location of sampling sites in Chengdu and Wolong Nature Reserve S3 Section 2 Botswana study, a nation-wide PAS network S3 Figure S2 Location of sampling sites in a nation-wide PAS network in Botswana S3 Table S1 Compositions of the groups in the cluster analysis of data from Botswana S4 Section 3 Chile S5 Table S2 Compositions of the groups in the cluster analysis of data from Chile S6 Section 4 North America S6 Figure S3 Location of the sampling sites in the North American study S6 Table S3 Compositions of the groups in the cluster analysis of data from North America S7 Section 5 Global Air Pollutants Sampling (GAPS) network S8 Table S4 Site ID for Global Atmospheric Passive Sampling (GAPS) network S8 Figure S4 Dendrogram and composition plot for GAPS data of 2007 S9 Figure S5 Dendrogram and composition plot for GAPS data of 2008 S9 Table S5 Group averages for cluster analysis based on compositional GAPS data of 2007 S10 Table S6 Group averages for cluster analysis based on compositional GAPS data of 2008 S10 Section 6 Western Canadian mountains S11 Fig. S6 Location of the transects Revelstoke, Yoho and Observation Peak in Western Canada S11 Table S7 Composition of the groups in the cluster analysis of data from the Western Canadian S12 Mountains Section 7 Tianjin-Changdao Islands, Northern China S12 Figure S7 Location of six sampling sites in Tianjin and four sampling sites on the Changdao Islands S13 Section 8 Synthetic data set of three regional studies S14 Table S8 Group averages for cluster analysis based on synthetic dataset from three regional studies S14 References S15 S1 SECTION 1: Chengdu-Wolong Natural Reserve, Southwestern China6 Duplicate XAD-PAS samples were collected at seven sites in Wolong Natural Reserve (WNR), a mountainous area at the eastern edge of the Tibetan Plateau in Western Sichuan Province, China, for six-month intervals for two and half years.6 From April 2007 to April 2008, duplicates samples were also deployed for two consecutive six month periods (one winter and one summer period) at a site in Chengdu, a city of 11 million inhabitants located in the Sichuan basin about 80-105 km to the East of the WNR. Therefore, samples taken during this year were used for the cluster analysis. With the WNR, the sites are along a valley and up the windward slope of Balang Mountain reaching the Pass at 4485 m a.s.l. The lowest and highest sites within WNR were approximately 80 kilometers apart. The sampling duration was 182 days for all samples. There were 30 PAS samples retrieved, i.e. 15 for winter and summer periods, respectively. (see Figure S1) The data are notated according to sampling period and site. The first capital letter (S or W) stands for summer or winter sampling period. This is followed by one or two capital letter(s) for different sites (CD for Chengdu; in the WNR (N) in the order of increasing altitudes: N1 for Gengda; N2 for Panda Center; N3 for Sandaoqiao; N4 for Dengsheng; N5 for Beimuping; N6 for 95 kilometer milestone; N7 for Pass. The last lower-case letter (a or b) indicates one of the duplicates. For example, S-N1a and S-N1b stand for summer duplicates at Gengda; W- N1a and W-N1b for winter duplicates at the same site. No duplicate was available for the highest site (S-N7 and W-N7). Eleven POPs compounds were measured, including HCB, -HCH, -HCH, -HCH, -HCH, p,p’-DDT, p,p’-DDE, p,p’-DDD, o,p’-DDT, PCB28, and PCB52. The result of the cluster analysis is displayed in Figures 1 and 2 in the main paper. As listed in Table 2 in the main paper there are five groups identified by cluster analysis based on compositional data. The samples were classified principally by season, as a winter group and three summer groups are formed. Thirteen of the fifteen winter samples are in the ‘winter’ group with highest HCB fraction. Nine of the fifteen summer samples are in the ‘summer’ group. ‘Summer-urban’ group consists of summer duplicates from Chengdu (S-CDa, S-CDb) with a composition high in -HCH, p,p’-DDT, p,p’-DDE , o,p’-DDT, PCB28, and PCB52. The ‘summer-local contamination’ group consists of summer duplicates from Sandaoqiao (S- N3a, S-N3b) with a composition high in -HCH and -HCH. In previous studies it was reported that the soil at Sandaoqiao was contaminated by HCHs in the past. This was also the case for the soil at the Panda Center site.7 There is also a ‘mixed’ group with four samples, two summer samples from Panda Center (S- N2a, S-N2b) and two winter samples from Pass (W-N7) and 95 kilometer milestone (W-N6a). This mixed group disappears when HCB was not included in the cluster analysis (Fig. 3 in the main text). S2 Figure S1 Location of sampling sites in Chengdu and Wolong Nature Reserve (WNR) (modified from ref.6) SECTION 2: Botswana5 In this study XAD-PAS samples were collected at 15 sites, an inland area of Botswana (Figure S2). All sites have similar altitudes ranging 295 m-371 m a.s.l. Five sites (E1 through E5) were along the Eastern border of Botswana where the majority of the population resides and where pesticides are used on vegetables and crops. Ten sites (from O1 through O10) were in the Okavango Delta area (only three of those sites are shown in Figure S2), which was repeatedly sprayed with DDT and endosulfan in the past.5 The 13 compounds measured in this work included HCB, α-HCH, γ-HCH, o,p’-DDE, TC, CC, TN, dieldrin, dacthal, Endo- I, Endo-II, Endo. Sulfate, and CT (chlorothalonil). Figure S2 Location of selected sampling sites in a nation-wide PAS network in Botswana For clustering results, please see Figure 4 in the main text and Table S1. Five groups were formed. Since HCB was found very much evenly distributed nation-wide in this study, the highest HCB fraction value of 0.374 indicates the ‘O-Delta’ group is the cleanest. Also according to the sum of POPs, the O-Delta group had the lowest levels (Table S1). In S3 chemical compositions, this group was dominated mainly by HCB and endosulfan, a pesticide used in the past. This group contains 6 sites being scattered over the Okavango Delta. It implies that the Delta area shares a very uniform POPs composition and thus belongs to the same airshed, having similar contributions from both regional and long-range atmospheric transport. There were another four sites in the Okavango Delta area that fell into another three groups due to contributions from local emission sources. Nokaneng, a village, was unique in chemical composition, having very high o,p’-DDE and chlordane contributions, and formed a group of its own (‘O7-DDE’ group in Table S1). O1 and O4 had high lindane contributions and constituted the ‘lindane’ group, together with sites E1 and E3 (Table S1). Sites in this group were from rather different geographical locations. It is the similar POPs source profiles and, in turn, the similar POPs compositions that make them a group. O1 is near a tourist camp and O4 is at the airport. It is quite possible that lindane was used in these locales. Table S1 Normalized compositions of the groups in the cluster analysis of data from Botswana Group no. of Sum of HCB -Endo trans-chlordane dieldrin lindane o,p-DDE sites POPs E4-dieldrin 1 79 ng/PAS 0.085 0.519 0.013 0.236 0.018 0.003 O-Delta 6 17 ng/PAS 0.374 0.411 0.014 0.015 0.051 0.012 EEO 3 31 ng/PAS 0.241 0.319 0.095 0.008 0.096 0.007 O7-DDE 1 51 ng/PAS 0.116 0.136 0.181 0.005 0.073 0.305 Lindane 4 73 ng/PAS 0.124 0.286 0.038 0.031 0.354 0.004 The same argument holds for site in the village of Seronga (O10) which formed a group with Mayalapye (E2) and Kasane (E5), two towns in the eastern part of Botswana. This group (‘EEO’ in Table S1) was featured by a relatively high portion of trans-chlordane. What Seronga and Kasane also have in common is that the sampling site was on the property of the police station. Maybe the police had used chlordane as termiticide. Site E4, Pandamatenga, again in a police station, is also a single site group, having high portion of dieldrin and -Endosulfan (‘E4-dieldrin’ in Table S1). In this study it is clearly demonstrated that cluster analysis is able to separate sites that are heavily influenced by local sources from those that are not. SECTION 3: Chile3 20 PAS were deployed in 2006-2007 for one year along three altitudinal transects in Chile.3 The three transects were very far apart; the distance between the northern and southern transect was ca.