Copy this text
Assessment of C, N and Si isotopes as tracers of past ocean nutrient and carbon cycling
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.
Keyword(s)
marine chemistry, carbon, nitrogen, silicon, paleoceanography, stable isotopes
Full Text
File | Pages | Size | Access | |
---|---|---|---|---|
10.1002/essoar.10504265.1 - Preprint | 41 | 1 Mo | ||
10.1002/essoar.10504265.2 - Preprint V2 | 54 | 4 Mo | ||
Publisher's official version | 59 | 2 Mo |