Oxygen-nutrient relationships in the Pacific Ocean

In the northeastern Pacific Otean the oxygen-phosphatc and oxygen-nitratc relationships vary systematically with latitude. The variation above the oxygen minimum zone is much more pronounced than below it. The slopes of these relationships in general increase with increasing latitude. In the entire water column these slopes vary with depth. A seasonnl effect on the slopes of the oxygen-phosphate and oxygen-nitrate relationships, similar to that with decreasing latitude, is observed; the winter slopes are higher than the summcr slopes. Potential temperature versus preformed phosphate diagrams were constructcd for different stations in the Pacific and Indian Oceans to study their water masses. Postma (1964) plotted dissolved oxygen concentrations, O,, versus phosphate concentrations, PO.,, from stntions nt different latitudes (55”N to 62’s) in the Pacific Otean, and found n variable AO, : APO, ratio with depth. Pytkowicz (1964) nnd Park (19670) found a linear relationship of 02 versus PO4 nbove the oxygen minimum zone off the Oregon coast. AlvarezBorrego et al. (1972, 1975) tested Redfield’s model for OY-nutrient relationships and found it consistent with the field data, showing that the variation of the 02-nutrient relationship slopes with depth, latitude, and time of the year is due to mising between different water types with different preformed portions of Oand nutrients. Diagranls of 02 versus nutrient may thus be used to characterize water masses and preformed nntrient (Redfield 1942) versus temperature diagrams may be used to detect and trace water mnsses thnt are not very well identified by T-S dingrams. The purpose of this work js to study the 1 This work \vas supported by National Science Foundation grnnts GX-381F7 and GA-12113 and Office of Naval Research contract NO0014Gi’-A0369-0007 undcr project NR-083-102. The “Conseio Nacional de Ciencia v Tccnoloeia” of Mexico snpported the work of S. Alvarez-Borrego. This papcr compriscs part of n dissertation submitted by S. Alvarrz-Borrego in partial fulfillmcnt of the requirements for the Ph.D. at Oregon State University. O---PO, and O,-NO:, relationships for tlle northeastern Pacific Ocenn and soutlieastcm Bering Sea, nnd to trace Pacific Intermedinte \Vnters using prcformed nutrient versus potentinl temperature, 8, tliagrains.