Geographic variations in the nitrogen isotope composition of surface particulate nitrogen and new production across the North Atlantic Ocean

摘要: Abstract Natural 15 N / 14 ( δ N) was determined in suspended particulate matter (SPM) and plankton tow samples (20- 233-μm mesh nets) during extensive surveys along E–W transects from Halifax, Nova Scotia, to the Canary Islands fall of 1992 spring 1993. This is first study reporting measurements with NO − 3 NH + 4 uptake rates North Atlantic. During both cruises, SPM net-plankton lower oligotrophic waters compared values eutrophic areas. The lack correlation between euphotic zone integrated concentration rate at times suggested that contrast regions could not be explained by regenerated production, even though preferred substrate most regions. In fact, based on a analysis, this isotope fractionation nitrate residence time τ ) were two major factors controlling 1992. 1992, region 100–170 d) consistent accumulated product equation closed systems new 4–5‰. contrast, 7–40 d), an open system equation. Isotope e for growth estimated 2.4‰ upwelling off Morocco. 1993, no correlations observed dynamics, probably because horizontal advection. Based low 5–30 d, used as reactant, it variations 2–3‰ either NO3 or .