Article ID Journal Published Year Pages File Type
7699079 Marine Chemistry 2016 42 Pages PDF
Abstract
A vertical increase in δ15N ratios from phytoplankton biomass to the surface sediment by ~ 2.5‰ is attributed to early diagenetic degradation in the water column and at the water/sediment interface. The δ15N ratios of sediments are mainly controlled by the N-isotope signature of nitrate on the outer shelf and upper continental slope. Nutrient-enriched deep water ascends at the shelf breaks due to the influence of internal waves and tides or curl-driven shelf break upwelling. The δ15N of upwelling nitrate at the shelf breaks is ~ 3‰ lower than that of nitrate from the inner shelf. This difference in nitrate sources is expressed in a band of decreasing δ15N ratios of surface sediments at the shelf breaks. The hydrodynamic upwelling regime at the shelf breaks flushes significant amounts of suspended matter from the mesopelagic ocean across the shelf break as indicated by amino acid monomer patterns of suspended matter.
Related Topics
Physical Sciences and Engineering Chemistry Chemistry (General)
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