TABLE 1.

Sampling locations and chemical characteristics of nifH clone libraries

Sampling locationYr sampledTemp (°C) range during samplingpH[NH3] (μM)[NO3] (μM)Max. [H2S] (mmol/liter)% Crustal seawaterbCells/ml
Marker 33, Axial Volcano199945-78a4.6a2.528.72.4a76.0a1.17 × 105a
Marker 33, Axial Volcano200020-32a5.8a2.214.50.2a84.7a1.15 × 105a
Puffer (diffuse) Endeavour200027-396.132.5No datad0.46895.61.67 × 105
Deep-sea Endeavour200027.8c≤1c40c0c5.0 × 104c
  • a From Huber et al. (31).

  • b (Lowest Mg content/seawater Mg content) × 100.

  • c Based on standard deep-seawater with no detectable hydrothermal plume signal.

  • d Puffer [NO3] probably 0 to 5 μM, based on temperature and ammonia concentration.