Diagenetic alterations of amino acids and organic matter in the upper Pearl River Estuary surface sediments
2011
J. Zhang | R. Zhang | Q. Wu | N. Xu
The objective of this study was to investigate the sources, diagenetic alterations of, and bacterial contributions to sediment organic matter (OM) in the upper Pearl River Estuary. Sediment analyses were conducted for three size fractions of OM, including coarse particulate OM (CPOM), fine particulate OM (FPOM), and ultrafiltered dissolved OM (UDOM). Results showed that the highest and lowest carbon (C): nitrogen (N) ratios were in CPOM and UDOM, respectively, indicating CPOM was relatively enriched in organic C, whereas FPOM was enriched in N-containing molecules. Distributions of amino acids and their D-isomers among the sediment fractions indicated that the percentage of total N represented by total hydrolysable amino acids, C- and N-normalized yields of total D-amino acids, and C- and N-normalized yields of D-alanine, D-glutamic acid, D-serine could be used as diagenetic indicators of sediment OM. Correlations between the N yields in total D-amino acids and total hydrolysable amino acids, and total N yields suggested that the bacterial N in general reflected the bulk N changes in CPOM, FPOM, and UDOM. Our results demonstrate the crucial role of bacteria as a N source in the terrestrial (soil and vascular plant debris) OM transported by the river.
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