Jill Sutton

Univ Brest, CNRS, IRD, Ifremer, Institut Universitaire Européen de la Mer, LEMAR, Univ Brest, CNRS, IRD, Ifremer, Institut Universitaire Européen de la Mer, LEMAR
Author ProfileAbstract
Biological productivity in the ocean directly influences the
partitioning of carbon between the atmosphere and ocean interior,
thereby controlling the distributions of many elements and their
isotopes in the ocean. Through this carbon cycle feedback, changing
ocean productivity has long been hypothesized as a key pathway for
modulating past atmospheric carbon dioxide levels and hence global
climate. To reconstruct climate impacts from temporal changes in
paleoproductivity, robust proxies are needed to test the connection
between past ocean productivity, nutrient biogeochemistry, ocean
circulation and climate. Here we compile water column carbon (C),
nitrogen (N) and silicon (Si) stable isotopes from GEOTRACES-era data in
four key ocean regions to review geochemical proxies of oceanic carbon
and nutrient partitioning based on the C, N, and Si isotopic composition
of marine sediments. Relationships between water column isotope
distributions, ocean productivity, and nutrient utilization are
discussed. The potential for isotope measurements in sedimentary
archives to record aspects of past ocean productivity are evaluated,
along with key uncertainties and limitations associated with each proxy.
Constraints on past ocean productivity, nutrient cycling and utilization
during late Quaternary glacial-interglacial cycles and over the Cenozoic
are examined. This review highlights opportunities for future research
using multielement proxy applications and emphasizes the importance of
such applications to reconstructing Cenozoic climate evolution.