Fig. 2.

Compilation of the (A) δ¹⁵N and (B) N content of foraminifera-bound N and bulk sedimentary N records in the SCS and open Pacific. In SCS core MD97-2142, FB-δ¹⁵N (filled circles) and N content (open circles) are shown for the planktonic foraminifera species O. universa (red circles) and G. ruber (blue circles) and for bulk sedimentary N (black line). Previously published bulk sedimentary δ¹⁵N and N content from SCS cores 17940 and 17954 are also shown (green and brown lines) (27, 28). One open Pacific data set is a last ice age/Holocene FB-δ¹⁵N comparison in cores from along the Line Islands in the central equatorial Pacific (purple diamonds) (36). The latitudes of the five cores are 0.22°S, 1.27°N, 2.46°N, 2.97°N, 5.2°N, and 6.83°N. Each core corresponds to paired LGM and Holocene data, with the FB-δ¹⁵N from both the LGM and the Holocene increasing northward from the equator; from the assemblage of cores, no LGM-to-Holocene difference is observed. A second open Pacific data set is a record of FB-δ¹⁵N from the western tropical north Pacific [ODP Site 871 (5.56°N, 172.35°E); blue triangles]. This record shows no clear FB-δ¹⁵N decrease from the last ice age to the Holocene, in contrast to SCS FB-δ¹⁵N. The locations of the sediment cores are shown in Fig. S9.