Table 1

Rates of biological activity at representative sites (23). n/a indicates that SO4 2– is present throughout the drilled hole and, consequently, that there is no base to the SO4 2– reduction zone in the sampled sediment column.

LocationBase of SO42− reduction zone (mbsf)SO42− flux downward to subsurface (mol cm−2year−1)SO42− flux due to CH4 oxidation (% of total)Total subsurface respiration (mol CO2 cm−2year−1)Photosynthesis of overlying ocean (mol CO2 reduced cm−2 year−1)
Ocean-margin sites
798B (Japan Sea)104.2 (±1.3) × 10−6 808.4 (±2.6) × 10−6 2.3 × 10−3
681C (Peru Margin)308.1 (±2.5) × 10−7 851.6 (±0.5) × 10−6 4.9 × 10−3
1175 (Nankai Trough)111.3 (±0.6) × 10−6 432.6 (±1.2) × 10−6 1.8 × 10−3
Open-ocean sites
851 (Equatorial Pacific)n/a2.8 (±2.5) × 10−9 05.6 (±5.0) × 10−9 9.3 × 10−4
834 (Lau Basin)n/a2.0 (±2.2) × 10−9 04.0 (±4.4) × 10−9 6.7 × 10−4
1149 (Izu-Bonin Trench)n/a1.3 (±0.6) × 10−8 02.6 (±1.2) × 10−8 4.8 × 10−4