ACTIVITY OF THE RESPIRATORY ELECTRON-TRANSPORT SYSTEM AND RESPIRATIONRATES WITHIN THE OXYGEN MINIMUM LAYER OF THE ARABIAN SEA

Measurements of the activity of the respiratory electron transport sys tem (ETS) at 15 stations in the Arabian Sea during the northeast monso on (December 1988) yield high respiration rates that do not correlate with the trends in primary productivity. The rates are unlikely to be sustained by the supply of carbon associated with the sinking particle s alone, and seem to suggest a major role for dissolved and/or suspend ed organic matter in fuelling oxygen consumption and denitrification. The data are utilized to compute a denitrification rate of 24-33 Tg N y-1 in the Arabian Sea. This estimate agrees with the estimate based o n the exports of nitrate deficits outside the denitrification zone. Th e ventilation time of the denitrifying layer is calculated as approxim ately 1 year.