Supplemental Information

Catalytic ozone destruction mechanisms involving bromine (Br)(Orlando, 2003)

“As shown by both measurements and models, *** about 40–50% of theavailable inorganic bromine is present in the form of BrO in the sunlit stratosphere(HOBr and BrONO2 contribute about 10–20% each), and catalytic cyclesinvolving reaction of BrO with ClO, HO2, and NO2 result in ozone depletion, e.g.,

Br + O3→ BrO + O2

BrO + HO2 → HOBr + O2

HOBr + h → OH + Br Catalytic cycle 1OH + O3 → HO2 + O2

net: 2 O3 → 3 O2

Br + O3 → BrO + O2

BrO + ClO → Br + Cl + O2 Catalytic cycle 2Cl + O3 → ClO + O2

net: 2 O3 → 3 O2

Br + O3 → BrO + O2BrO + NO2 + M → BrONO2 + MBrONO2 + h → Br + NO3 Catalytic cycle 3”NO3 + h → NO + O2

NO + O3 → NO2 + O2

net: 2 O3 → 3 O2”

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Table S-1: Kendall’s Tau Correlation Statistics for NADP Samples with Detected Br-

[Site ID, NADP monitoring site identifier; mm, millimeters; mL, milliliters; Tau, Kendall’s Tau correlation statistic; p-value, probability of deciding that correlation is by chance]

    Relation of Br- with Analyte Concentrations

Mercury Chloride NitratePrecipitatin Depth (mm)

Sample Volume (mL)

Site ID

Number of

Weekly Samples

(n) Tau p-value Tau p-value Tau p-value Tau p-value Tau p-valueAL02 4 -- -- 0.41 0.4386 0.00 1.0000 -0.41 0.4386 -0.41 0.4386AL03 16 -- -- -0.28 0.1503 0.25 0.2102 -0.05 0.8165 -0.06 0.7453AL10 28 -- -- 0.15 0.2759 0.46 0.0009 -0.41 0.0036 -0.43 0.0022AL19 7 -- -- 0.37 0.2664 -0.16 0.6338 0.05 0.8738 -0.05 0.8738AL24 14 -- -- 0.16 0.4362 0.00 1.0000 -0.05 0.824 -0.02 0.9114AL99 15 -- -- 0.28 0.1677 0.05 0.7983 0.18 0.3845 0.18 0.385AR02 35 -- -- 0.10 0.4399 0.13 0.3146 -0.19 0.1448 -0.18 0.1575AR03 25 -- -- -0.30 0.0540 0.21 0.1645 -0.32 0.0404 -0.32 0.0382AR16 22 -- -- -0.12 0.4447 -0.04 0.7914 0.27 0.0935 0.28 0.0830AR27 20 -- -- 0.19 0.2513 0.06 0.7185 -0.06 0.7179 -0.04 0.8185AZ03 34 -- -- 0.09 0.4744 0.15 0.2106 -0.31 0.0122 -0.22 0.0689AZ06 51 -- -- 0.17 0.0830 0.10 0.3105 -0.38 0.0002 -0.30 0.0026AZ97 30 -- -- 0.24 0.0702 0.44 0.0011 -0.18 0.1880 -0.20 0.1423AZ98 25 -- -- 0.26 0.0729 0.08 0.5711 -0.52 0.0005 -0.52 0.0004AZ99 32 -- -- 0.15 0.2542 0.22 0.0919 -0.08 0.5620 -0.07 0.6085CA28 11 -- -- 0.04 0.8751 0.07 0.7533 -0.11 0.6374 -0.07 0.7533CA42 38 -- -- 0.37 0.0016 0.15 0.2068 -0.12 0.2955 -0.11 0.3519CA45 19 -- -- -0.11 0.5383 0.10 0.5622 -0.46 0.0101 -0.45 0.0102CA50 5 -- -- -0.20 0.6242 0.60 0.1416 0.60 0.1416 0.60 0.1416CA66 11 -- -- 0.20 0.3889 0.50 0.0344 -0.52 0.0278 -0.57 0.0152CA67 16 -- -- 0.09 0.6418 0.29 0.1365 -0.14 0.4841 -0.02 0.9259CA75 17 -- -- 0.15 0.4047 0.28 0.1336 -0.19 0.3144 -0.10 0.5839CA76 9 -- -- -0.30 0.2790 -0.12 0.6650 0.03 0.9134 0.00 1.0000CA88 24 -- -- 0.38 0.0136 0.20 0.1902 -0.22 0.1506 -0.20 0.1902CA94 27 -- -- -0.01 0.9497 0.11 0.4240 0.05 0.7519 0.02 0.8663CA96 10 -- -- -0.30 0.2411 -0.30 0.2411 -0.16 0.5279 -0.25 0.3213CA99 11 -- -- -0.26 0.2704 -0.21 0.3851 0.19 0.4284 0.19 0.4311CO00 33 -- -- 0.35 0.0060 0.39 0.0023 -0.44 0.0006 -0.39 0.0021CO01 20 -- -- 0.06 0.7148 -0.09 0.5953 -0.13 0.4449 -0.06 0.7399CO02 35 -- -- 0.05 0.6850 -0.10 0.4174 0.18 0.1516 -0.13 0.2840CO08 28 -- -- 0.12 0.3777 0.12 0.4110 -0.10 0.4576 -0.12 0.3998CO09 6 -- -- -0.36 0.3299 -0.50 0.1725 -0.07 0.8455 -0.07 0.8455CO10 27 -- -- 0.19 0.1704 0.11 0.4230 -0.18 0.1980 -0.14 0.3321CO15 47 -- -- -0.10 0.3236 -0.10 0.3328 -0.22 0.0316 -0.16 0.1191CO19 34 -- -- 0.10 0.4198 0.16 0.1839 -0.28 0.0260 -0.29 0.0207CO21 27 -- -- 0.11 0.4375 0.03 0.8175 -0.33 0.0188 -0.34 0.0141CO22 27 -- -- 0.22 0.1182 0.20 0.1572 -0.22 0.1173 -0.19 0.1700CO89 21 -- -- -0.04 0.8296 0.08 0.6226 0.07 0.6667 -0.21 0.2074

2830

32

Table S-1, ContinuedCO90 25 -- -- -0.41 0.0059 -0.24 0.0951 0.20 0.1800 0.08 0.5887CO91 38 -- -- 0.09 0.4400 0.23 0.0456 -0.26 0.0267 -0.25 0.0295CO92 26 -- -- 0.06 0.7003 0.10 0.4971 -0.01 0.9639 -0.11 0.4416CO93 24 -- -- -0.22 0.1505 -0.11 0.4802 0.09 0.5448 0.13 0.3912CO94 16 -- -- -0.37 0.0501 -0.22 0.2547 0.07 0.7152 0.06 0.7498CO96 19 -- -- -0.20 0.2494 -0.10 0.5647 -0.21 0.2347 -0.15 0.3877CO97 17 0.82 0.2207 -0.33 0.0730 -0.44 0.0157 0.15 0.4268 0.15 0.4047CO98 21 -- -- -0.16 0.3289 -0.14 0.3933 -0.09 0.6035 0.01 0.9514CO99 34 -- -- 0.13 0.2995 0.17 0.1761 -0.21 0.1010 -0.19 0.1328CT15 30 -- -- -0.04 0.7711 0.16 0.2302 -0.03 0.7991 -0.04 0.7711FL03 55 -- -- 0.32 0.0014 0.07 0.4634 -0.15 0.1286 -0.15 0.1467FL05 77 -- -- 0.43 <0.0001 0.25 0.0025 -0.36 <0.0001 -0.36 < 0.0001FL11 153 1.00 0.0415 0.52 <0.0001 0.10 0.0853 -0.30 <0.0001 -0.30 < 0.0001FL14 48 -- -- 0.02 0.8579 0.22 0.0400 -0.29 0.0077 -0.29 0.0083FL23 43 -- -- -0.09 0.4156 0.11 0.3192 -0.12 0.2890 -0.12 0.2700FL32 73 -- -- 0.62 <0.0001 0.07 0.3855 -0.29 0.0006 -0.28 0.0010FL41 73 -- -- 0.34 <0.0001 0.11 0.1985 -0.27 0.0019 -0.27 0.0016FL96 29 -- -- 0.51 0.0002 0.23 0.0911 -0.27 0.0502 -0.28 0.0419FL99 128 -- -- 0.62 <0.0001 0.13 0.0316 -0.39 <0.0001 -0.40 < 0.0001GA09 49 -- -- 0.35 0.0007 0.12 0.2412 -0.32 0.0026 -0.33 0.0019GA20 44 -- -- 0.32 0.0039 0.25 0.0248 -0.40 0.0004 -0.40 0.0003GA33 111 -0.08 0.6064 0.58 <0.0001 0.14 0.0434 -0.08 0.2624 -0.08 0.2187GA41 18 -- -- -0.15 0.4084 0.44 0.0165 -0.26 0.1567 -0.27 0.1458GA99 26 -- -- -0.13 0.3497 0.07 0.6243 -0.07 0.6241 -0.06 0.6886IA08 12 -- -- 0.25 0.2651 0.31 0.1655 -0.03 0.8897 -0.06 0.7815IA23 18 -- -- -0.06 0.7571 0.06 0.728 -0.07 0.6990 -0.08 0.6708ID02 10 -- -- 0.26 0.3121 0.42 0.0994 -0.05 0.8547 -0.14 0.5828ID03 22 -- -- 0.41 0.0089 0.30 0.0533 -0.31 0.0465 -0.20 0.2112ID11 27 -- -- 0.06 0.6719 0.09 0.5116 -0.35 0.0147 -0.21 0.1328IL11 20 -- -- 0.08 0.6198 -0.02 0.9210 -0.13 0.4468 -0.17 0.3056IL18 20 -- -- 0.27 0.1024 0.44 0.0074 -0.26 0.1242 -0.23 0.1701IL46 14 -- -- -0.18 0.3878 0.16 0.4542 -0.23 0.2740 -0.23 0.2740IL63 35 -- -- -0.31 0.0137 0.12 0.3417 0.02 0.8968 0.03 0.7954IL78 11 -- -- 0.00 1.0000 0.04 0.8751 0.09 0.6936 0.19 0.4321IN20 17 -- -- -0.14 0.4533 0.09 0.6171 0.20 0.2779 0.24 0.1824IN22 24 -- -- -0.16 0.2933 -0.17 0.2604 0.15 0.3172 0.16 0.2936IN34 24 -- -- 0.20 0.1765 -0.12 0.4231 0.12 0.4229 0.17 0.2496IN41 14 -- -- 0.08 0.6957 -0.27 0.1988 0.33 0.1172 0.34 0.1052KS07 27 -- -- 0.13 0.3653 0.03 0.8126 0.03 0.8461 0.03 0.8126KS31 26 -- -- -0.04 0.7555 0.02 0.9114 -0.06 0.6723 -0.08 0.5631KS32 16 -- -- -0.27 0.1592 -0.13 0.4958 -0.27 0.1592 -0.27 0.1592KY03 22 -- -- -0.17 0.3011 -0.04 0.8183 -0.07 0.6665 -0.07 0.6458KY10 10 -- -- -0.20 0.4171 0.11 0.6521 -0.25 0.3213 -0.25 0.3213KY19 11 -- -- -0.43 0.0693 -0.47 0.0483 0.55 0.0216 0.55 0.0220KY22 16 -- -- 0.02 0.9273 -0.21 0.2733 -0.11 0.5526 -0.16 0.4113KY35 16 -- -- -0.16 0.4010 -0.27 0.1616 0.30 0.1233 0.13 0.5136KY99 16 -- -- 0.16 0.4074 -0.20 0.2903 0.15 0.4344 0.17 0.3823LA12 39 -- -- 0.43 0.0003 0.41 0.0006 -0.34 0.0041 -0.38 0.0015LA30 63 -- -- 0.30 0.0012 0.26 0.0038 -0.29 0.0018 -0.28 0.0026

Table S-1, Continued.MA01 126 0.55 0.2786 0.46 < 0.0001 -0.03 0.5834 0.05 0.3829 0.05 0.4599MA08 24 -- -- -0.03 0.8420 -0.09 0.5499 -0.07 0.6537 -0.08 0.5836MA13 17 -- -- 0.34 0.0616 0.24 0.1835 -0.09 0.6179 0.07 0.7085MA14 49 -- -- 0.67 < 0.0001 -0.19 0.0673 0.15 0.1525 0.16 0.1248MA22 7 -- -- 0.48 0.1530 -0.79 0.0172 0.69 0.0390 0.79 0.0172MD07 18 -- -- 0.02 0.9083 -0.04 0.8180 0.24 0.1792 0.18 0.3187MD08 16 -- -- 0.35 0.0688 -0.03 0.8557 -0.07 0.7156 -0.07 0.7161MD13 53 -- -- -0.27 0.0059 0.08 0.4280 -0.10 0.3159 -0.09 0.3799MD15 98 -- -- 0.44 < 0.0001 0.01 0.8816 -0.09 0.2286 -0.09 0.1884MD18 86 -- -- 0.39 < 0.0001 0.06 0.4637 -0.14 0.0639 -0.13 0.0901MD99 38 -0.26 0.4987 0.00 0.9693 0.20 0.1001 -0.14 0.2424 -0.15 0.2224ME00 21 -0.82 0.2207 -0.27 0.1029 0.28 0.0850 -0.22 0.1760 -0.03 0.8536ME02 17 -- -- 0.06 0.7357 0.06 0.7678 0.14 0.4475 0.17 0.3758ME04 11 -0.18 0.718 -0.11 0.6345 -0.19 0.4282 -0.06 0.8116 -0.08 0.7513ME08 19 -- -- -0.31 0.0799 -0.28 0.1078 0.06 0.7477 0.09 0.5919ME09 21 -- -- 0.34 0.0355 0.23 0.1613 -0.26 0.1134 -0.17 0.2864ME96 42 0.82 0.2207 0.27 0.0174 0.02 0.8867 -0.07 0.5106 -0.11 0.3292ME98 52 -- -- 0.26 0.0090 0.05 0.6500 -0.02 0.8298 0.00 1.0000MI09 18 -- -- 0.21 0.2374 0.17 0.3413 -0.15 0.3807 -0.14 0.4241MI26 17 -- -- -0.16 0.3850 -0.19 0.3010 0.03 0.8682 0.01 0.9670MI48 12 -- -- -0.05 0.8348 -0.14 0.5316 0.10 0.6760 0.14 0.5316MI51 15 -- -- 0.43 0.0311 0.21 0.2923 -0.16 0.4203 -0.17 0.3939MI52 22 -- -- -0.12 0.4564 -0.26 0.1087 0.15 0.3590 0.16 0.3024MI53 17 -- -- 0.22 0.2150 0.33 0.0631 0.22 0.2303 0.17 0.3422MI98 12 -- -- 0.09 0.6772 0.05 0.8359 -0.47 0.0378 -0.48 0.0323MI99 28 -- -- -0.14 0.3061 -0.15 0.2968 0.13 0.3353 0.09 0.4951MN01 20 -- -- 0.26 0.1228 0.14 0.4118 -0.23 0.1669 -0.26 0.1228MN08 15 -- -- 0.36 0.0752 0.26 0.2038 -0.49 0.0166 -0.48 0.0169MN16 12 1.00 -- 0.05 0.8321 0.02 0.9437 -0.11 0.6209 0.02 0.9437MN18 23 -- -- 0.04 0.8071 -0.06 0.7043 -0.15 0.3559 -0.14 0.3567MN23 15 -- -- -0.16 0.4218 -0.44 0.0272 0.23 0.2465 0.15 0.4508MN27 15 -- -- 0.23 0.2556 0.23 0.2561 -0.42 0.0434 -0.27 0.1796MN28 7 -- -- -0.39 0.2243 -0.68 0.0334 0.10 0.7613 0.10 0.7613MN32 15 -- -- 0.28 0.1677 0.18 0.3850 -0.15 0.4739 -0.13 0.5065MN99 16 -- -- -0.25 0.1963 -0.11 0.5804 -0.01 0.9632 -0.07 0.7125MO03 24 -- -- -0.12 0.4338 -0.13 0.3907 0.14 0.3635 0.10 0.5116MO05 19 -- -- -0.19 0.2704 0.06 0.7490 0.09 0.6182 0.09 0.5938MS10 22 -- -- 0.14 0.3743 0.36 0.0236 -0.36 0.0253 -0.37 0.0203MS12 60 -1.00 -- 0.52 < 0.0001 0.13 0.1546 -0.26 0.0053 -0.28 0.0028MS19 27 -- -- 0.28 0.0574 0.30 0.0417 -0.05 0.7513 -0.03 0.8564MS30 17 -- -- -0.01 0.9664 -0.08 0.6734 0.10 0.5840 0.10 0.5840MT00 32 -- -- -0.04 0.7820 0.09 0.4739 -0.24 0.0653 -0.16 0.1929MT05 12 -- -- -0.14 0.5316 -0.14 0.5316 0.24 0.2971 0.30 0.1866MT07 20 -- -- -0.23 0.1617 -0.10 0.5364 -0.32 0.0544 -0.29 0.0735MT96 26 -- -- 0.06 0.6575 -0.04 0.7733 -0.41 0.0041 -0.21 0.1376MT97 8 -- -- 0.40 0.1702 -0.43 0.1376 -0.52 0.0785 -0.57 0.0478MT98 14 -- -- 0.02 0.9124 0.00 1.0000 0.10 0.6191 -0.09 0.6600NC03 34 -- -- 0.19 0.1400 0.27 0.0313 -0.22 0.0780 -0.23 0.0732

33

Table S-1, Continued.NC06 106 -- -- 0.51 < 0.0001 0.06 0.4216 -0.12 0.0921 -0.16 0.0216NC17 4 -- -- 0.55 0.2786 0.55 0.2786 -0.18 0.7180 -0.18 0.718NC25 23 -- -- 0.04 0.7859 0.30 0.0609 -0.31 0.0473 -0.29 0.0688NC29 76 -- -- 0.32 0.0001 0.06 0.5004 -0.17 0.0441 -0.17 0.0414NC34 28 -- -- -0.10 0.4845 0.19 0.1619 -0.05 0.7340 -0.03 0.8261NC35 42 -- -- 0.20 0.0720 0.28 0.0125 -0.44 0.0001 -0.44 0.0001NC36 31 -- -- 0.00 0.9862 0.15 0.2551 0.03 0.8092 0.03 0.8361NC41 29 -- -- 0.06 0.6616 0.16 0.2456 -0.11 0.4240 -0.12 0.3917NC45 16 -- -- -0.25 0.1975 0.13 0.4904 -0.34 0.0803 -0.38 0.048ND00 13 -- -- 0.10 0.6574 0.17 0.4479 -0.38 0.0872 -0.31 0.1641ND08 16 -- -- 0.15 0.4155 0.14 0.4692 -0.27 0.1596 -0.27 0.1477ND11 20 -- -- 0.28 0.0998 -0.08 0.6216 -0.47 0.0051 -0.39 0.0212NE15 22 -- -- 0.21 0.1793 0.41 0.011 -0.37 0.0205 -0.40 0.0129NE99 21 -- -- 0.11 0.5159 -0.03 0.8771 0.06 0.7101 0.02 0.9261NH02 16 -- -- -0.42 0.0278 -0.37 0.0542 -0.19 0.3353 -0.18 0.3593NJ00 78 -- -- 0.61 < 0.0001 -0.05 0.5519 -0.04 0.5813 -0.08 0.3307NJ39 54 -- -- 0.79 < 0.0001 -0.38 < 0.0001 0.20 0.0371 0.16 0.107NJ99 29 -- -- 0.22 0.1242 -0.04 0.8003 0.12 0.3809 0.09 0.5207NM01 26 -- -- 0.02 0.9113 0.12 0.4098 -0.05 0.7546 -0.06 0.6721NM07 29 -- -- 0.16 0.2409 0.07 0.6096 -0.31 0.0209 -0.30 0.0244NM08 25 -- -- 0.13 0.3890 0.06 0.6842 -0.16 0.3033 -0.18 0.2411NM12 23 -- -- 0.31 0.0431 0.15 0.3121 -0.28 0.0701 -0.26 0.0887NV03 16 -- -- 0.31 0.1091 0.33 0.0822 -0.15 0.4364 -0.19 0.3143NV05 51 -- -- -0.09 0.3550 0.03 0.7558 -0.03 0.7743 -0.08 0.4038NY01 20 -- -- 0.22 0.1917 -0.02 0.9221 -0.25 0.1258 -0.19 0.2412NY06 19 -- -- 0.42 0.0172 -0.04 0.8285 0.03 0.8567 -0.06 0.7181NY08 20 -- -- 0.05 0.7900 -0.24 0.1621 0.18 0.2864 0.18 0.2868NY10 12 -- -- -0.03 0.8881 0.13 0.5735 -0.29 0.2053 -0.29 0.2053NY20 12 -- -- -0.32 0.1636 -0.20 0.3662 -0.11 0.6266 -0.11 0.6266NY22 8 -- -- 0.29 0.3223 0.07 0.8046 0.21 0.4579 0.36 0.2160NY28 4 -- -- -0.55 0.2786 -0.55 0.2786 0.55 0.2786 0.55 0.2786NY29 17 -- -- 0.07 0.7079 -0.02 0.9008 -0.05 0.7708 -0.08 0.6476NY52 17 -- -- 0.18 0.3505 0.32 0.0896 -0.49 0.0107 -0.43 0.0219NY68 19 -- -- -0.29 0.0947 0.09 0.6189 0.00 1.0000 0.00 1.0000NY92 5 -- -- -0.32 0.4485 0.11 0.8005 -0.11 0.8005 -0.11 0.8005NY96 143 -- -- 0.60 < 0.0001 -0.14 0.0188 0.09 0.1129 0.08 0.1554NY98 13 -- -- -0.17 0.4526 -0.18 0.4174 0.11 0.6172 -0.01 0.9503NY99 16 -- -- 0.01 0.9631 -0.09 0.6437 -0.02 0.9263 -0.05 0.7814OH09 11 -- -- -0.11 0.6345 -0.31 0.2050 0.46 0.0573 0.53 0.0265OH15 7 -- -- -0.15 0.6447 0.15 0.6447 -0.45 0.1666 -0.35 0.2820OH17 18 -- -- -0.07 0.6735 -0.13 0.4668 0.17 0.3368 0.20 0.2667OH49 25 -- -- 0.10 0.4801 0.15 0.3006 -0.09 0.5252 -0.09 0.5407OH54 14 -- -- -0.10 0.6330 -0.03 0.9050 0.18 0.4028 0.18 0.4033OH71 21 -- -- 0.04 0.8082 -0.13 0.4301 0.04 0.7847 0.01 0.9516OK00 31 -- -- 0.05 0.7153 0.25 0.0657 -0.39 0.0035 -0.37 0.0055OK17 24 -- -- -0.11 0.4725 0.22 0.1659 -0.17 0.2698 -0.23 0.1508OK29 17 -- -- 0.02 0.9333 0.28 0.1318 -0.26 0.1633 -0.29 0.1117OR09 4 -- -- 0.00 1.0000 0.00 1.0000 -0.33 0.4969 -0.67 0.1742OR10 16 -- -- -0.37 0.0591 -0.12 0.5196 0.23 0.2317 0.20 0.3116

Table S-1, ContinuedOR18 11 -- -- 0.15 0.5297 0.19 0.4321 -0.17 0.4782 -0.22 0.3458OR97 26 -- -- 0.17 0.2392 -0.06 0.7002 0.17 0.2387 0.22 0.1352PA00 15 -- -- 0.05 0.8014 0.15 0.4504 0.17 0.3924 0.15 0.4504PA02 11 -- -- 0.05 0.8555 0.00 1.0000 -0.32 0.2025 -0.23 0.3626PA13 30 0.09 0.7822 0.27 0.0538 0.23 0.0881 -0.35 0.0105 -0.36 0.0094PA15 13 -- -- 0.19 0.3871 0.09 0.666 -0.32 0.1382 -0.36 0.0959PA18 15 -- -- 0.08 0.6870 -0.09 0.6507 0.16 0.4203 0.15 0.4504PA21 18 -- -- 0.31 0.1000 -0.15 0.423 -0.25 0.1911 -0.28 0.14PA29 12 -- -- 0.14 0.5342 0.05 0.8359 -0.39 0.0843 -0.45 0.0452PA30 31 0.21 0.5028 0.34 0.0122 0.16 0.223 -0.24 0.0754 -0.27 0.0472PA42 22 -- -- 0.15 0.3506 0.15 0.3506 0.15 0.3657 0.17 0.2937PA47 24 -- -- 0.01 0.9388 -0.27 0.0864 0.20 0.2099 0.23 0.1447PA52 17 -- -- 0.19 0.2971 -0.12 0.5316 -0.15 0.4282 -0.18 0.3375PA60 28 -- -- 0.45 0.0013 0.20 0.1515 -0.12 0.4070 -0.22 0.1199PA71 14 -- -- 0.03 0.8669 0.15 0.4676 -0.21 0.3139 -0.20 0.3422PA72 20 0.00 1.0 -0.01 0.9477 -0.19 0.2644 0.04 0.8182 0.04 0.7928PA83 13 -- -- 0.46 0.0385 0.55 0.0135 -0.25 0.2564 -0.22 0.3166PA90 11 -- -- 0.46 0.0674 0.17 0.506 -0.50 0.0460 -0.50 0.0460PA98 10 -- -- 0.14 0.6165 0.19 0.4832 -0.17 0.5465 -0.14 0.6165SC03 20 -- -- 0.34 0.0498 0.41 0.0179 -0.62 0.0003 -0.64 0.0002SC05 108 -0.23 0.4168 0.40 < 0.0001 0.08 0.2542 -0.27 0.0001 -0.26 0.0002SC06 44 -- -- 0.25 0.0267 0.05 0.6745 0.01 0.9163 0.03 0.7929SD04 22 -- -- 0.14 0.3713 0.13 0.4031 -0.29 0.0755 -0.24 0.1415SD08 14 -- -- 0.11 0.5785 -0.23 0.2665 0.13 0.5405 0.25 0.2216SD99 20 -- -- -0.14 0.4079 0.17 0.3209 -0.15 0.3709 -0.17 0.3209TN00 8 -- -- -0.22 0.4509 0.00 1.0000 0.00 1.0000 0.00 1.0000TN04 14 -- -- -0.02 0.9121 0.29 0.1511 -0.19 0.3472 -0.20 0.3203TN11 11 -- -- 0.02 0.9336 0.08 0.7395 -0.12 0.6179 -0.17 0.5060TN14 15 -- -- 0.06 0.763 0.08 0.6877 -0.06 0.763 -0.04 0.8407TX02 21 -- -- 0.02 0.9266 0.02 0.9023 -0.20 0.2312 -0.22 0.1771TX03 84 -- -- 0.58 < 0.0001 0.25 0.0013 -0.41 < 0.0001 -0.41 < 0.0001TX04 27 -- -- -0.06 0.6572 0.05 0.7194 -0.30 0.0399 -0.25 0.0794TX10 74 -- -- 0.43 < 0.0001 0.36 < 0.0001 -0.37 < 0.0001 -0.38 < 0.0001TX16 39 -- -- 0.21 0.0697 0.38 0.0010 -0.31 0.0083 -0.28 0.0152TX21 38 -0.33 0.6015 0.01 0.9387 0.22 0.0689 -0.30 0.0143 -0.28 0.0184TX22 37 -- -- 0.29 0.0155 0.32 0.0085 -0.34 0.005 -0.32 0.0070TX43 30 -- -- 0.31 0.0273 0.04 0.7685 -0.10 0.4725 -0.19 0.1621TX56 32 -- -- 0.18 0.1798 0.33 0.0118 -0.27 0.0400 -0.27 0.0434UT01 83 -- -- 0.10 0.191 0.25 0.0011 -0.32 < 0.0001 -0.33 < 0.0001UT08 21 -- -- 0.25 0.1218 0.00 1.0000 -0.03 0.8315 -0.03 0.8318UT09 25 -- -- -0.12 0.4203 0.21 0.1551 -0.32 0.0328 -0.29 0.0520UT98 14 -- -- 0.14 0.5076 0.57 0.0058 -0.58 0.0048 -0.54 0.0080UT99 23 -- -- 0.01 0.9364 0.00 0.9788 -0.22 0.1506 -0.22 0.1586VA00 43 -- -- 0.18 0.0970 0.23 0.0383 -0.28 0.0108 -0.33 0.0029VA13 18 -- -- 0.02 0.9082 0.23 0.1914 -0.14 0.4527 -0.12 0.5045VA24 19 -- -- -0.11 0.5418 0.36 0.0408 -0.21 0.2363 -0.22 0.2091VA28 16 -- -- -0.01 0.9636 0.10 0.616 -0.06 0.7496 -0.06 0.7496VA98 17 -- -- -0.19 0.3142 0.09 0.6148 0.13 0.5023 0.20 0.2756VA99 19 -- -- -0.13 0.4505 0.08 0.6408 -0.13 0.4721 -0.08 0.6408

Table S-1, ConcludedVT01 8 -- -- -0.74 0.0120 -0.30 0.3148 0.30 0.3148 0.30 0.3148VT99 13 -- -- -0.17 0.4474 -0.13 0.5695 0.21 0.3431 0.35 0.1141WA14 51 -- -- 0.59 < 0.0001 0.04 0.6754 0.17 0.0862 0.17 0.0892WA19 11 -- -- 0.10 0.6847 0.02 0.9353 -0.46 0.0618 -0.46 0.0618WA21 17 -- -- 0.08 0.6689 0.25 0.1995 -0.41 0.0325 -0.43 0.0261WA24 11 -- -- 0.33 0.1712 0.37 0.1262 -0.56 0.0238 -0.41 0.0910WA98 28 -- -- -0.20 0.1524 0.16 0.2678 -0.21 0.1307 -0.34 0.0156WA99 10 -- -- 0.42 0.0994 0.00 1.0000 -0.14 0.5828 -0.14 0.5828WI09 7 -- -- -0.41 0.2097 0.00 1.0000 -0.62 0.0599 -0.51 0.1169WI10 14 -- -- -0.14 0.5046 -0.05 0.8245 -0.43 0.0351 -0.34 0.0963WI25 15 -- -- -0.10 0.6177 -0.04 0.8421 -0.13 0.5169 -0.14 0.4857WI28 16 -- -- -0.23 0.2320 -0.04 0.8185 0.14 0.4624 0.19 0.3353WI35 11 -- -- -0.28 0.2362 0.06 0.8127 -0.25 0.3046 -0.28 0.2362WI36 11 -- -- -0.07 0.7533 -0.24 0.3086 0.00 1.0000 0.06 0.8142WI37 12 -- -- -0.05 0.8348 -0.17 0.4445 -0.16 0.4851 -0.14 0.5316WI98 13 -- -- -0.04 0.8516 0.16 0.4550 0.15 0.4927 0.19 0.3834WI99 13 -- -- -0.46 0.0318 -0.43 0.0429 0.25 0.2437 0.17 0.4251WV04 10 -- -- -0.10 0.7095 0.15 0.5764 -0.15 0.5764 -0.05 0.8523WV05 10 -- -- -0.62 0.0239 -0.29 0.2800 -0.19 0.4918 -0.08 0.7683WV18 24 -- -- -0.04 0.7828 -0.16 0.3042 0.13 0.4080 0.08 0.6163WY00 35 -- -- 0.13 0.2783 -0.08 0.5117 0.02 0.8417 -0.08 0.5026WY02 29 -- -- 0.13 0.3440 0.06 0.6773 -0.13 0.3340 -0.14 0.3069WY06 47 -- -- 0.21 0.0456 0.30 0.0040 -0.11 0.2891 -0.08 0.4123WY08 33 -- -- 0.39 0.0024 0.43 0.0008 -0.42 0.0011 -0.42 0.0011WY94 10 -- -- 0.21 0.4040 0.69 0.0072 -0.63 0.0155 -0.60 0.0205WY95 31 -- -- 0.04 0.7316 -0.07 0.5717 0.05 0.7059 -0.06 0.6683WY97 23 -- -- 0.20 0.2010 0.25 0.0987 -0.07 0.6505 -0.03 0.8314WY98 47 -- -- -0.03 0.7470 0.05 0.6383 -0.12 0.2415 -0.14 0.1814WY99 23 -- -- 0.19 0.2282 0.11 0.4704 0.00 0.9786 -0.02 0.8937

34

35

Geographic Information System Analysis for Figure S-3 and S-7

I. Coastal Cl- Deposition Raster Extraction:

Data:

Coastline Data: https://www.ngdc.noaa.gov/mgg/shorelines/Global Self-consistent, Hierarchical, High-resolution Geography Database (GSHHG): Intermediate resolution

Deposition Maps: http://nadp.sws.uiuc.edu/NTN/maps.aspxNational Atmospheric Deposition (NADP) Cl Deposition Grids

Procedure:

Determine total Cl- deposition within 50 km of the U.S. coastline, as defined NADP deposition rasters using ESRI ArcMap 10.3.1 and Python 2.7. Map projection is Albers Equal Area Conic USGS

1. Create Coastline Buffera. Use the Intermediate Resolution (i) GSHHS-shp polygon shapefile from Global

Self-consistent Hierarchical High-resolution Shorelines (GSHHG)b. Use the interactive selection method in ArcMap to select/save the polygon

pertaining to North Americac. Run the Feature to Line (Data Management) tool in ArcMap to convert the North

American polygon feature into a polyline featured. Run the Buffer (Analysis) tool in ArcMap to create a 50-km buffer around the

polyline coastline (see Figure S-1)

2. Extract Deposition Raster based on Buffera. Run the Extract By Mask (Spatial Analysis) tool in ArcMap

i. Raster Input: NADP Cl- deposition rasterii. Mask: 50 km U.S. coastline buffer feature

3. Sum total Cl- Deposition from Extracted Rastera. Convert extracted raster to Python (NumPy) Array

i. Run the Raster to NumPy Array tool in the ArcPy and NumPy Python modules

import arcpy, numpy

raster = r'C:\*raster_name*'

array = arcpy.RasterToNumPyArray(raster, nodata_to_value = 0)

x = float(array.sum())

print xii. Note: No data cells are set to zero; summed values are rounded in

Python as float binary type.iii. The output will be the summed value of Cl- deposition from all grid cells

within 50 km of a U.S coastline in kg/ha

36

37

38

394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283

b. Total summed Cl- values is then multiplied by the area of each grid cell in hectares. NADP deposition grid cells are (2338.383 m x 2338.383 m) = 546.8 hectares/cell

4. Determine Total Area of Extracted Rastera. Convert extracted coastal raster to an integer raster; necessary for ArcMap raster

analysis toolset.b. Use Raster Calculator, Int(*raster name*)c. Run the Build Raster Attribute Table (Data Management) tool to create an

attribute table for the new integer rasterd. Using attribute table statistics, determine the sum of the count column from the

attribute table. This will give the total number of cells in the analysis region.e. Multiply total number of cells by area of each cell to get the total analysis area

(546.8 hectares/cell)

II. CLBr 95th Percentile Ratio Calculations

Data: Calculate mean Cl:Br 95th percentile ratios for each site by year. Use most complete year (2010) to make raster of Cl:Br95th percentile ratios.Procedure:

1. Load Cl:Br 95th percentile ratio data into ArcMap as (X, Y) points. Use definition query to exclude sites where the value = 0 in 2010, ‘ClBr2010 <> 0’

2. Use IDW (Spatial Analyst) tool to create an IDW2 raster using the Cl:Br2010 field, snap the grid cells and set spatial extent to equal that of the NADP Cl- deposition raster, and set output cell size to be 2338.383 meters. Leave other variables as default.

3. Use Raster Calculator to divide 1995 NADP Cl Deposition Raster / Cl-:Br-95th IDW raster.

4. Use NumPy array (Step 3 from above) to sum grid cells in raster and multiply by area of grid cell @ 546.8 hectares/cell.

84858687888990919293949596979899

100101102103

105106107108109110111112113114115116

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Table S-2: Calculation of Cl- and estimation of Br- deposition within 50 km of U.S. Coasts.Cl- Deposition : Within 50 km of U.S. Coastline

Year Sum Cl- Dep (kg/ha)

1988 594,671.4375 Cell Size (X,Y) (meters) 2338.383, 2338.383

2001 735,960.43752002 750,699.1875 Area Per Cell (Hectares) 546.82003 750,218.37502004 658,373.1875 Total Cell Count within 50 km Coastal Area2005 869,740.5625 2012 - 2015 94,5682006 804,409.3750 1988 - 2012 94,2202007 708,832.37502008 906,088.5625 Total 50 km Coastal Area (Hectares)2009 752,073.3125 2012 - 2015 51,710,113.912010 594,973.9375 1988 - 2012 51,519,826.292011 706,541.12502012 710,824.87502013 521,216.71882014 646,137.93752015 753,583.5000

Cl:Br Ratio

Sum(kg/ha) Sum * (ha/cell) (kg)

Tonnes Br-

SUM(ClDep1995 / Cl:Br95th(2010)) 47,984 26,237,879 26,238

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119120

R-Project Methodology for Precipitation Intensity and Total Depth Plots

Data from valid NTN samples with collection dates in 2015 and 2016 were obtained from the NADP Central Analytical Laboratory database. All samples with reported bromide concentrations greater than zero were included, comprising 3,917 of 19,186 valid samples for the period. Precipitation data from the NADP’s network of electronic recording rain gages were obtained from the NADP Program Office. Precipitation intensity values were calculated from the maximum 15-minute precipitation amount recorded. This combined data set represents 248 of the 277 active stations in 2015 – 2016. Data were analyzed in the R ver. 3.3.3 statistical package using R-studio ver. 1.0136.

274 sites had valid samples with Br >0 in 2015-2016 of 277 sites reporting data over this period.

248 sites had valid samples with Br >0 and 15-minute precipitation data in 2015 – 2016.

Sea Salt Aerosol Depletion

Sea-salt particles can be depleted of Cl- and Br- by several reactions, such as reduction of NaCl and NaBr by nitric (HN03) and sulfuric (H2SO4) acids in polluted air, resulting in volatilization of gaseous hydrochloric (HCl(g)) and hydrobromic (HBr(g)) acids, Br2(g), BrO(g), and HOBr(g) (Ayers et al., 1999; Gabriel et al., 2002; Newberg et al., 2005). Photo-oxidation of Br- and halogen interexchange reactions between Cl- and Br- also deplete sea-salt aerosols of Br- resulting in release of Br2(g) from the particulate phase (Newberg et al., 2005). The trends in Cl-:Br-

95th do not indicate any changes in sea-salt aerosol chemistry that might help to explain the observed negative trends in Br- wet deposition.

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123124125126127128129

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134135136137138139140

Figure S-1. 50 km Coastline Mask (blue) for chloride and bromide deposition calculations from NADP annual deposition grids, derived from Global Self-consistent Hierarchical High-resolution Shorelines (GSHHS, green).

141142143

144

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Figure S-2. Kendall’s Tau correlation for detected bromide and corresponding chloride concentrations in weekly NADP wet deposition samples June 2009-April 2016.

146

147148

149

150

Figure S-3. Kendall’s Tau correlation for detected bromide and corresponding nitrate concentrations in weekly NADP wet deposition samples, June 2009-April 2016.

151152153

Figure S-4. Censored seasonal Kendall test trend slopes for chloride:bromide 95th percentile concentration ratios in weekly composited NADP wet-deposition samples, 2009-2016.

154

155156

Figure S-5. Mann-Kendall trends for annual precipitation depth for National Atmospheric Deposition Program wet-deposition monitoring sites, 2001-2015. Note:

2016 data were unavailable online at the time of analysis.

157

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159

Figure S-6. Seasonal Kendall trends for spring-summer precipitation depth, for National Atmospheric Deposition Program wet-deposition monitoring sites, 2001-

2015. Note: 2016 data were unavailable online at the time of analysis.

160

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Figure S-7. Annual U.S. coastal Cl- deposition obtained from NADP Cl- deposition raster data, and estimated Br- deposition obtained by dividing annual Cl- raster data by 2010 Cl-:Br- 95th percentile ratio raster.

163

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Figure S-8. United States methyl bromide inventories (use) 1992-2014. Data source: https://www.epa.gov/ods-phaseout/methyl-bromide, accessed July 21, 2016, and Stone (2013).

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