Paired bulk organic and individual amino acid delta N-15 analyses of bivalve shell periostracum: A paleoceanographic proxy for water source variability and nitrogen cycling processes

摘要

Developing high-resolution, well-dated, marine proxies of environmental, climatic, and oceanographic conditions is critical in order to advance our understanding of the ocean's role in the global climate system. While some work has investigated bulk and compound specific stable nitrogen isotope (delta N-15) values in bivalve shells as proxies for environmental variability, the small concentrations of nitrogen found in the organic matrix of the shell calcium carbonate (hereafter carbonate) makes developing high resolution records challenging. This study investigates the potential of using the bulk and amino acid delta N-1(5) values of bivalve periostracum, the protein layer on the outside of the shell, as a proxy archive of nitrogen cycling processes and water source variability.