The presented data for As and V have extended the limited basis for comparison, so that inter-ocean fractionation processes can now be recognized. The concentrations of both As and V show regular increases in the ocean deep water as it passes from the North Atlantic (As 19.0; V 32.6 nmol I-') via the South Atlantic (As 21. I nmol I-') and Indian Ocean (As 22.5; V 35.6 nmol I-') lo the Pacific Ocean (As 24.0; V 36.4 nmol I-'). The magnitude ofbiological recycling for V and As. as deduced from interoceanic fractionation, is consistent with estimates based on particle or algal compositions.