Hydro-biogeochemical alterations to optical properties of particulate organic matter in the Changjiang Estuary and adjacent shelf area

Base-extracted particulate organic matter (BEPOM) collected in low (spring) and high (summer) runoff seasons the Changjiang Estuary adjacent nearshore/offshore shelf areas was examined using absorption fluorescence spectroscopy. Parallel factor analysis (PARAFAC) identified two humic-like (C1p C2p) biologically-refractory components protein-like (C3p C4p) bioreactive components. Absorption coefficient a350p, C1p C2p of BEPOM showed strong positive correlations with carbon (POC), were generally higher spring than summer. C4p correlated positively Chl a, summer spring. In inner estuary, an anthropogenic POM signal from highly polluted Huangpu River effectively by fluorescent component ratio (IT:IC)P. nearshore area during spring, resuspension within well-developed turbidity maximum zone (TMZ) supplied large amounts refractory into water column. fractions autochthonous source (i.e., algal bloom) dominant offshore A multivariate regression model inferred that export fluxes had a percentage labile fractions, which subsequently retained TMZ. However, these discharged contributing to hypoxia The season also transported buried sediment. This study highlights utilization optical analyses trace pollution sources reveal fate transport dynamics allowing better assessment its ecological consequences estuaries.