Sedimentary carbon-isotope systematics on the Amazon shelf

Sedimentary carbon systematics on the Amazon continental shelf were investigated using C-14 and delta(13)C measurements of sedimentary organic materials. Mass balance calculations indicate that the C-14 content of modern shelf muds results from burial of old (similar to 5000 yr BP) terrestrial soil carbon and bomb-C-14-enriched marine carbon, implying that most of the bomb-labeled riverine particulate carbon is not buried on the shelf. The C-14 signature of Amazon shelf deposits records the effects of both biogeochemical and sedimentary processes active in this dynamic environment.