Carbon and nitrogen isotopic composition of particulate organic matter and its biogeochemical implication in the Bering Sea

Abstract

Stable carbon and nitrogen isotopic composition of particulate organic matter (POM) were measured for samples collected from the Bering Sea in 2010 summer. Particulate organic carbon (POC) and particulate nitrogen (PN) showed high concentrations in the shelf and slope regions and decreased with depth in the slope and basin, indicating that biological processes play an important role on POM distribution. The low C/N ratio and heavy isotopic composition of POM, compared to those from the Alaska River, suggested a predominant contribution of marine biogenic organic matter in the Bering Sea. The fact that δ13C and δ15N generally increased with depth in the Bering Sea basin demonstrated that organic components with light carbon or nitrogen were decomposed preferentially during their transport to deep water. However, the high δ13C and δ15N observed in shelf bottom water were mostly resulted from sediment resuspension.