The PO 4 , δ 13 C and Cd depth distributions measured in the N. Atlantic Ocean during recent GEOTRACES and CLIVAR cruises are a result of biological and circulation processes, with in-situ uptake and remineralization of organic matter dominating in the upper ~300 m and mixing of water masses dominating in the thermocline and deep sea. The observed slopes of the NO 3 –PO 4 , preindustrial δ 13 C–PO 4 and (by analogy) Cd–PO 4 along isopycnals deviate significantly from that expected from Redfield in the thermocline and deep sea and in each case the observed slope is similar to the slopes of the end-member water masses being mixed. The depth increase in the Cd–PO 4 slope resulting from end-member mixing explains the observed kink at ~1 μM PO 4 in the Cd–PO 4 relationship in the N. Atlantic. The observation that the PO 4 - preindustrial δ 13 C–Cd relationship in the modern N. Atlantic is heavily influenced by end-member mixing throughout most of the water column complicates the use of δ 13 C and Cd as proxies of the paleocean’s nutrient distribution because changes in the PO 4 –δ 13 C–Cd composition of locally and remotely produced end-members water masses would change the PO 4 , δ 13 C and Cd depth distributions in the paleo N. Atlantic Ocean. [ABSTRACT FROM AUTHOR]