Origin of the Particulate Organic Matter in a Monsoon-Controlled Bay in Southern China

In this study, the isotopic composition (δ13C and δ15N), total organic carbon content, nitrogen C/N ratios of suspended particulate matter (POM) in Zhanjiang Bay, which is a semi-enclosed bay with concentrated artificial activities Southern China, were analyzed order to investigate seasonal variations principal POM sources monsoon region. summer, δ13C δ15N values showed weak correlation chlorophyll (Chl a), suggesting that terrigenous dominant. However, winter, correlated Chl middle mouth. Moreover, significant during indicating contribution situ phytoplankton was relatively important affected by winter. Compared corresponding values, exhibited complex spatial distribution. By using Bayesian mixing model, upper bay, source mainly from marine (49%) almost an equilibrated all mouth, originated (53%) contrast, soil (63%) sourced runoff upstream basin. Our results suggest shifts should be taken into account when estimating C or N mass balance monsoon-controlled bay.