Can primary production contribute non-labile organic matter in the sea: Amino acid enantiomers along the coast south of the Changjiang Estuary in May

2014 ◽  
Vol 129 ◽  
pp. 343-349 ◽  
Author(s):  
Zhuo-Yi Zhu ◽  
Ying Wu ◽  
Jing Zhang ◽  
Thorsten Dittmar ◽  
Ying Li ◽  
...  
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Primary Production ◽  
Changjiang Estuary ◽  
Labile Organic Matter ◽  
The Changjiang Estuary ◽  
Amino Acid Enantiomers

scholarly journals Influence of cross-shelf water transport on nutrients and phytoplankton in the East China Sea: a model study

Ocean Science ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 27-43 ◽  
Author(s):  
L. Zhao ◽  
X. Guo
Keyword(s):  
Surface Layer ◽  
Primary Production ◽  
Chlorophyll A ◽  
East China Sea ◽  
Seasonal Variations ◽  
Changjiang Estuary ◽  
Shelf Break ◽  
East China ◽  
The East China Sea ◽  
The Changjiang Estuary

Abstract. A three dimensional coupled biophysical model was used to examine the supply of oceanic nutrients to the shelf of the East China Sea (ECS) and its role in primary production over the shelf. The model consisted of two parts: the hydrodynamic module was based on a nested model with a horizontal resolution of 1/18 degree, whereas the biological module was a lower trophic level ecosystem model including two types of phytoplankton, three elements of nutrients, and biogenic organic material. The model results suggested that seasonal variations occurred in the distribution of nutrients and chlorophyll a over the shelf of the ECS. After comparison with available observed nutrients and chlorophyll a data, the model results were used to calculate volume and nutrients fluxes across the shelf break. The annual mean total fluxes were 1.53 Sv for volume, 9.4 kmol s−1 for DIN, 0.7 kmol s−1 for DIP, and 18.2 kmol s−1 for silicate. Two areas, northeast of Taiwan and southwest of Kyushu, were found to be major source regions of oceanic nutrients to the shelf. Although the onshore fluxes of nutrients and volume both had apparent seasonal variations, the seasonal variation of the onshore nutrient flux did not exactly follow that of the onshore volume flux. Additional calculations in which the concentration of nutrients in Kuroshio water was artificially increased suggested that the oceanic nutrients were distributed in the bottom layer from the shelf break to the region offshore of the Changjiang estuary from spring to summer and appeared in the surface layer from autumn to winter. The calculations also implied that the supply of oceanic nutrients to the shelf can change the consumption of pre-existing nutrients from rivers. The response of primary production over the shelf to the oceanic nutrients was confirmed not only in the surface layer (mainly at the outer shelf and shelf break in winter and in the region offshore of the Changjiang estuary in summer) but also in the subsurface layer over the shelf from spring to autumn.

scholarly journals Amino acid enantiomers in old and young dissolved organic matter: Implications for a microbial nitrogen pump

2019 ◽  
Vol 247 ◽  
pp. 207-219 ◽  
Author(s):  
Taylor A.B. Broek ◽  
Amy L. Bour ◽  
Hope L. Ianiri ◽  
Thomas P. Guilderson ◽  
Matthew D. McCarthy
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Amino Acid Enantiomers ◽  
Microbial Nitrogen

scholarly journals Characterization of Marine-Surface-Dissolved Organic Matter via Amino Acid Enantiomers and Its Implications Based on Diel and Seasonal Observations

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 685
Author(s):  
Zhuo-Yi Zhu ◽  
Ying-Chun Zhou ◽  
Wen-Chao Ma ◽  
Ying Wu ◽  
Ming Li ◽  
...  
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Carbon Cycling ◽  
Northern South China Sea ◽  
Marine Ecosystem ◽  
Amino Acid Enantiomers ◽  
Marine Surface ◽  
High Frequency Sampling ◽  
Dom Composition

Due to the essential roles of dissolved organic matter (DOM) in both microbiol food loop and marine carbon cycling, changes in marine DOM composition have an important impact on the marine ecosystem and carbon cycling. In October 2014 and June 2015, two field investigations for the DOM in the upper 200 m were conducted in the slope region of the northern South China Sea to characterize the DOM composition via amino acid enantiomers. In June, our sampling locations were under upwelling impact induced by an eddy-pair event, whereas in October there were no eddies. High-frequency sampling (a few hours interval) over 24 h reveals that the variability of the amino acid carbon yield (min. 0.2%) and the D/L alanine ratio (min. 0.02) is larger than its corresponding analytical and propagated errors, suggesting solid short-term changes for these two molecular-based indicators. Section samples from June showed a lower D/L alanine ratio (0.43 vs. 0.53) and a GABA mol% (1.0% vs. 1.6%) relative to the section samples from October, suggesting that DOM in June is more fresh (less degraded) compared to that in October. A higher serine mol% (19.5% vs. 13.2%) and lower D/L serine ratio (0.06 vs. 0.24) from the diel observation in June relative to October further indicates that phytoplankton, rather than bacteria, plays an more important role in DOM composition alternation. This is consistent with the higher phytoplankton biomass found in June, promoted by the eddy-pair.

scholarly journals Absorption features of chromophoric dissolved organic matter (CDOM) and tracing implication for dissolved organic carbon (DOC) in Changjiang Estuary, China

2013 ◽  
Vol 10 (7) ◽  
pp. 12217-12250 ◽  
Author(s):  
X. Y. Zhang ◽  
X. Chen ◽  
H. Deng ◽  
Y. Du ◽  
H. Y. Jin
Keyword(s):  
Organic Matter ◽  
Absorption Spectrum ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Dissolved Organic Carbon ◽  
Changjiang Estuary ◽  
Chromophoric Dissolved Organic Matter ◽  
Model Parameters ◽  
The Changjiang Estuary ◽  
Linear Diffusion

Abstract. Chromophoric dissolved organic matter (CDOM) represents the light absorbing fraction of dissolved organic carbon (DOC). Studies have shown that the optical properties of CDOM can be used to infer the distribution and diffusion characteristics of DOC in the estuary and coastal zone. The inversion of DOC concentrations from remote sensing has been implemented in certain regions. In this study we investigate the potential of tracing DOC from CDOM by the measurement of DOC, absorption spectrum of CDOM, Chla concentration, suspended sediment (SS), and salinity from cruises in different seasons around the Changjiang estuary. Our results show that around the Changjiang estuary the absorption coefficients of CDOM in general have the similar spatial and temporal characteristics as that of DOC, but the strength of the correlation between CDOM and DOC varies locally and seasonally. The input of pollutants from outside the estuary, the bloom of phytoplankton in spring, re-suspension of deposited sediment, and light bleaching all contribute to the local and seasonal variation of the correlation between DOC and CDOM. An inversion model for the determination of DOC from CDOM is established, but the stability of model parameters and its application in different environments need further study. We find that relative to the absorption coefficient of CDOM, the fitted parameters of the absorption spectrum of DOM are better indictors for the composition of DOC. In addition, it is found that the terrestrial input of DOC to Changjiang estuary is a typical two-stage dilution process instead of a linear diffusion process.

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