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Table 1 Compositions of discrete and diffuse vent fluids

From: Geochemically induced shifts in catabolic energy yields explain past ecological changes of diffuse vents in the East Pacific Rise 9°50'N area

   Temperature (°C) pH (25°C) (1) in situ pH Mg2+ mM Na+ mM (1) Cl+ mM SiO2 (aq) mM H2 (aq) μM H2S (aq) mM Fe2+ μM CH4 (aq) μM CO2 (aq) mM O2 (aq) μM (5) SO42- mM (1, 6) % hydrothermal fluid (4)
  Seawater 1.8 7.8 8.1 52.2 464 540 0.155 0 0 0 0 2.30 100 28.2 0
Northern Area                 
April 1991 hot endmember 368 2.6 3.2 0 139 154 9.90 3030 23.2 2190 172 44.8 - 0 100
  diffuse, measured 22 - - 49.7 - 530 0.88 0.36 0.90 151 0.070 5.90 - - 7.39
  diffuse, calculated 22 5.7 5.7 48.3 440 511 0.88 225 1.72 162 12.8 5.46 92.6 26.1 7.39
December 1993 hot endmember 365 3.6 5.7 0 188 212 11.3 700 7.30 1060 1000 204 - 0.18 100
  diffuse, measured 30.9 - - 49.6 - 522 0.57 0.33 0.28 24.2 5.80 9.57 - - 3.68
  diffuse, calculated 30.9 5.5 5.5 50.3 454 528 0.57 25.9 0.27 39.3 37.1 9.77 96.3 27.2 3.68
March 1994 hot endmember 363 3.5 5.1 0 222 249 12.6 680 8.50 1430 112 187 - 0.035 100
  diffuse, measured 29.9 - - 50.4 - 525 0.79 1.90 0.27 25.0 6.58 9.57 - - 5.06
  diffuse, calculated 29.9 5.4 5.4 49.6 452 525 0.79 34.5 431 72.5 5.68 11.7 94.9 26.8 5.06
October 1994 hot endmember 364 3.2 3.8 0 279 325 14.1 530 6.20 2730 86.0 146 - 1.55 100
  diffuse, measured 32.3 - - 48.1 - 524 0.92 6.79 0.11 69.9 4.83 8.54 - - 5.45
  diffuse, calculated 32.3 5.5 5.4 49.3 454 528 0.92 29.2 0.34 150 4.74 10.2 94.5 26.7 5.45
November 1995 hot endmember 366 3.0 3.9 0 391 466 14.8 360 6.70 6030 84.0 139 - 0 100
  diffuse, measured 33.3 - - 46.3 - 550 1.14 2.50 0.19 277 5.37 9.01 - - 6.69
  diffuse, calculated 33.3 5.4 5.3 48.7 459 535 1.14 24.2 0.45 406 5.65 11.5 93.3 26.3 6.69
November 1997 hot endmember 373 3.1 4.1 0 342 400 13.4 330 8.60 6640 95.0 117 - 0 100
  diffuse, measured 27.2 - - 50.5 - 534 0.72 0.75 0.003 170 2.52 4.70 - - 4.23
  diffuse, calculated 27.2 5.7 5.7 50.0 459 534 0.72 14.1 0.37 284 4.07 7.21 95.7 27.0 4.23
Southern Area                 
April 1991 diffuse, measured 55 - - 46.7 - 504 1.95 2.17 8.46 2.40 505 10.1 - - -
February-March hot endmember 160 3 (2) 3.7 0 126 (3) 136 12.7 6460 20.7 4080 213 31.0 - - 100
1992 diffuse, measured 23.3 - - 48.2 - 529 0.69 14.9 0.66 2.00 94.0 4.57 - - 4.28
  diffuse, calculated 23.3 6.2 6.2 50.0 479 523 0.69 277 0.89 175 9.12 3.53 95.7 27.0 4.28
December 1993 diffuse, measured 15.4 - - 50.5 - 532 0.23 0.13 0.001 9.20 2.87 2.70 - - -
March 1994 hot endmember 20.5 - - 0 - 269 5.57 8910 11.2 200 748 118 - - 100
October 1994 hot endmember 351 3 (2)   0 229 (3) 235 12.5 8390 14.3 1590 116 104 - - 100
  diffuse, measured 20.4 - - 49.7 - 526 0.66 6.75 0.21 11.5 15.6 4.96 - - 4.05
  diffuse, calculated 20.4 - 5.8 50.1 484 528 0.66 343 0.58 65.0 4.74 6.46 95.9 27.0 4.05
November 1995 hot endmember 341 3 (2) 3.7 0 297 (3) 301 13.8 4930 14.0 1550 106 95.7 - - 100
  diffuse, measured 24.7 - - 50.3 - 531 0.85 0.75 0.53 9.90 15.9 5.80 - - 5.06
  diffuse, calculated 24.7 5.7 5.7 49.5 484 528 0.85 250 0.71 78.7 5.38 7.04 94.9 26.8 5.06
November 1997 hot endmember 307 3 (2) 3.4 0 326 (3) 330 16.1 3550 11.3 742 121 81.9 - - 100
  diffuse, measured 18.2 - - 51.5 - 530 0.57 0.67 0.24 27.0 4.09 3.84 - - 2.57
  diffuse, calculated 18.2 6.0 6.1 50.9 490 535 0.57 91.3 0.29 19.1 3.11 4.35 97.4 27.5 2.57
April 2000 hot endmember 279 3 (2) 3.3 0 355 (3) 359 16.8 2700 11.2 517 108 77.0 - - 100
  diffuse, measured 11.9 - - 50.4 - 529 0.23 0.15 0.055 23.0 0.47 2.57 - - 0.42
  diffuse, calculated 11.9 7.0 6.9 52.0 494 539 0.23 12.5 0.051 2.39 0.50 2.65 99.5 28.1 0.42
  1. Fluid data for high temperature fluids and measured diffuse fluids are from Von Damm and Lilley, 2004 [13]
  2. Northern Area: Hot vent fluids are from Bio9 and Bio9' and the associated diffuse fluids from BM9Rifia, BM91o and BM12
  3. Southern Area: High temperature fluids are from Tube Worm Pillar (TWP) and the diffuse fluids from Y vent at the base of TWP
  4. (1) pH, sodium and sulfate concentrations of vent fluids are from Von Damm [14], unless otherwise indicated
  5. (2) pH was not measured but is approximated by comparison with similar vent fluids from Von Damm [14]
  6. (3) Na+ calculated by charge balance
  7. (4) Calculated assuming conservative behavior of SiO2(aq)
  8. (5) O2(aq) in diffuse fluids was calculated from conservative mixing, assuming 100 μMol O2 for pacific bottom seawater [30]
  9. (6) When sulfate concentrations are not reported, it is assumed to be zero in the endmember vent fluids