Table 13. Composition of free gas collected in syringes from sediment from Site 997. "Core, section" Depth (mbsf) O2 (ppmv) N2 (ppmv) CO2 (ppmv) C1 (ppmv) C2 (ppmv) C3 (ppmv) i-C4 (ppmv) n-C4 (ppmv) i-C5 (ppmv) n-C5 (ppmv) i-C6 (ppmv) n-C6 (ppmv) n-C7 (ppmv) C1/C2 C1/C2+ 164-997A- 6H-7 50 24000 196000 16400 769400 31.2 10.6 5.6 0.6 0.6 24700 15800 7H-1 50.5 13000 79000 23100 868900 34.3 10.6 5.2 0.3 0.4 25300 17100 8H-2 54.5 72000 313000 23600 568700 19.4 7.1 3.6 0.3 0.5 29300 18400 9H-1 61.5 2000 23000 27100 926700 35.7 13.1 7.2 0.9 1 0.2 26000 16000 10H-7 79.85 4000 25000 48400 904700 34.8 13.3 8.8 0.9 2.2 0.1 0.1 26000 15000 11H-3 83.5 80 8000 32600 949900 32.3 12.1 7.9 0.9 2.2 0.1 29400 17100 12H-6 97.42 1000 7000 34500 917700 32.1 13 11.4 1.1 3.2 0.2 0.1 28600 15000 13H-7 107.58 80 2000 47600 910600 34.3 17.5 15 1.6 7.3 0.2 0.1 26500 12000 14H-7 116.83 60 1000 30400 957500 31.4 16 14.6 1.8 8 0.2 0.1 30500 13300 16H-5 134 8000 29000 34700 760300 27 18.6 12.5 1.2 7.9 0.5 28200 11200 17H-5 143.4 76000 316000 19100 503000 14 12 0.6 0.3 11 0.3 0.3 35900 13100 19H-5 153.33 41000 171000 39800 701700 28.1 20.6 18 2 2.1 0.5 0.3 0.4 25000 9800 20H-6 165 39000 161000 48000 717100 32 20 19 2.1 18 0.5 0.4 22400 7790 22X-4 176.82 34000 139000 119600 645700 40.3 18.5 19 26.6 3.1 0.3 0.8 0.7 16000 5910 26X-5 209.5 16000 64000 171100 716900 74.6 22.2 29.2 5.1 27.7 1.2 0.9 0.7 9610 4440 27X-4 216.6 100 1000 145200 836700 116.7 11.9 11.4 2.5 11 0.8 0.4 7170 5410 28X-2 223.2 38000 158000 183800 598400 70.4 14.6 13.4 3.3 9.9 0.6 0.3 8500 5320 30X-3 235.4 6000 22000 236400 710600 97.6 20.9 20.5 5.4 14.7 1.1 0.4 7280 4420 31X-5 247 1000 1000 186600 781500 134.7 13.3 10.3 3 9 0.8 0.3 5800 4560 32X-4 255.1 26000 2000 152500 670800 131 12 8 3 9 1 0.4 5120 4080 34X-5 267.13 1000 1000 234600 739400 60 28 17 6 17 1.4 0.4 12300 5700 36X-5 284.15 177000 728000 4500 48800 6.2 0.3 0.3 7870 7180 38X-5 304.6 26000 104000 197400 593800 72 31 7 30 2 1 1 8250 4120 39X-5 314.2 26000 105000 141600 664200 180 14 8.2 2.6 14 1.2 0.5 3690 3010 41X-3 321.8 130 1000 223800 727400 131.2 15 17.5 6.1 23.4 2.1 1 0.6 5540 3690 42X-2 329 91000 371000 19000 458200 67.9 0.8 0.2 1.2 0.2 0.3 6750 6520 43X-1 337.1 115000 477000 92800 262600 51 7.1 8.3 2.2 7.6 0.8 0.2 5150 3400 44X-4 351.3 90 1000 136500 827100 226.1 7.4 2.2 7.4 0.9 0.2 3660 3390 46X-4 370.25 188000 770000 1700 6100 1.9 7.4 2.2 7.4 0.9 0.2 3220 306 48X-2 386.9 70 1000 113200 854900 401.2 4.7 1.2 11.5 0.9 0.4 2130 2040 52X-5 413.1 40 1000 139400 798900 350 10 14 2 26 1.4 1 0.1 2280 1980 54X-4 427.98 1000 1000 187000 700500 635 4 1 11 1 0.5 0.4 1100 1070 164-997B- 1X-2 320.1 11500 44000 194200 681600 104 13 21 5.4 23.9 2.1 0.8 7.1 6550 4000 2X-2 329.7 12000 46000 181400 682100 131 7 11.7 3.4 14.2 1.5 0.8 0.4 5210 4010 3X-2 339.3 90 1000 71100 900000 209 9 7.5 1.5 5.3 0.6 0.2 0.2 4310 3860 4X-1 414.3 109000 452000 37100 331800 232 2 0.4 3.2 1430 1400 5X-2 425.66 24000 127000 245700 529400 401 10 7 2.4 12 1 1320 1220 8X-5 449 11000 41000 91400 762600 863 1.5 0.9 3.9 0.5 884 877 11X-3 466.3 1000 1000 138600 782200 461.2 43 14 7.1 24.9 3.8 1.6 1.4 6.1 1700 1400 12X-3 474.21 1000 1000 43400 909200 434.3 15 5.4 2.5 7.7 1.3 0.6 0.6 0.5 2090 1950 13X-3 484.6 26000 102000 138200 661100 541.2 27 10.4 5 14.8 2.5 1 1 10.8 1220 1100 14X-2 492.7 100 1000 158600 772500 495.6 28 7.2 3.8 9.4 1.6 1560 1420 16X-3 504.9 1000 1000 204800 718500 681.9 43 11.2 6.6 16.4 3.2 1.3 1.6 0.6 1050 939 17X-1 510.5 4000 10000 153500 756400 491.1 27 7.2 4.4 9 2 0.8 1.1 0.3 1540 1390 18X-2 521.6 1000 1000 178900 762400 615.2 33 7.7 5.2 7.6 1.9 0.6 1 0.2 1240 1130 19X-3 532.7 10 300 121100 805800 636 35.5 8 5.3 7.3 2 0.6 0.8 1270 1160 20X-1 539.3 80 1000 149100 738900 547 29 7.5 4.8 7.5 1.8 0.8 1 1350 1230 22X-4 554.4 1000 1000 185600 727600 868.8 68 19 12 17 4.1 1.6 2 838 733 23X-6 566 1000 1000 181100 656900 671.4 42 978 921 24X-4 572.6 3000 6000 91700 944000 648.2 29 13 7 11.6 2.6 1 1 1460 1320 26X-4 583.2 4000 11000 176400 769600 920 94 28 13.5 22 4.7 2 1.8 837 709 27X-5 593.3 50 500 55700 938100 597.9 34 9.3 3.9 6.3 1.2 2 1.8 1570 1430 28X-4 600.67 40 300 42800 936300 613 35.7 12.5 4.7 8.7 2.1 0.9 7.9 1530 1380 29X-3 609.6 20 300 134100 849200 696.2 55 17.5 7.3 2.8 2.8 1.3 1.4 1220 1080 30X-3 619.2 30 400 22700 961500 631.8 30.2 10.4 4.7 9 1.9 1 1 1520 1390 31X-4 630.23 7000 24000 104100 847400 737.1 57 18.6 8 15.1 3 1.4 1.3 0.6 1150 1010 33X-4 640.07 20 300 79700 912300 784.7 59 17.7 7.3 14.5 3 1.4 1.3 1.1 1160 1030 34X-1 645 103000 427000 2400 451200 310 20.6 4.8 2.2 3.9 0.8 1460 1320 35X-5 658.8 2000 1000 26700 941100 588 36.5 6.6 3 5.5 1.2 0.5 0.4 1600 1470 37X-5 671.2 1000 1000 97300 875400 913 70 15.5 8.5 15 3 1 0.7 959 853 38X-5 679.9 60 400 34500 955600 788 42 9.3 5.1 9.9 1.3 0.5 0.4 1210 1120 42X-3 704.77 3000 5000 17800 941100 708.6 33 5.5 4.3 5.7 1.1 0.6 0.2 1330 1240 43X-4 716.8 10 300 46200 930800 660.3 30.7 5.5 3.2 5 1.1 0.4 0.4 0.2 1410 1320 45X-4 727.26 20 300 96000 878500 1057 73 12.7 9.3 13.5 2.8 1.1 1 0.4 831 751 46X-4 734.84 10 400 62300 923200 800.7 43.6 6.9 4.9 5.9 1.5 0.6 0.6 0.3 1150 1070 47X-4 745.7 20 300 38500 962800 793.7 36.3 5.1 3.3 3.2 1 1210 1140 "Notes: Oxygen (O2) and nitrogen (N2) concentrations are included as a guide to the amount of air contamination in each sample. C1 through C7 = the alkanes: methane, ethane, propane, butane, pentane, hexane, and heptane. " "Iso- and normal configurations of butane, pentane, and hexane are designated with i- and n- prefixes. C1/C2 = the methane/ethane ratio, and C1/C2+ = the ratio methane/the sum of (C2 through C6)."