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Biogeochemistry of organic matter and associated elements along the river-estuary-ocean continuum
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Optical and Molecular Signatures of Dissolved Organic Matter in Xiangxi Bay and Mainstream of Three Gorges Reservoir, China: Spatial-temporal Variations and Environmental Implications
Tuesday 8th @ 1350-1410, Conference Hall
Kai Wang* , Institute of Environmental and Biogeochemistry (eBig), School of Earth Sciences, Zhejiang University, Hangzhou 310027, China
Chen He, State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Changping District, Beijing 102249, China
Penghui Li, Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
Shangbin Xiao, College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang, 443002, China
Yongge Sun, Institute of Environmental and Biogeochemistry (eBig), School of Earth Sciences, Zhejiang University, Hangzhou 310027, China
Quan Shi, State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Changping District, Beijing 102249, China
Ding He, Institute of Environmental and Biogeochemistry (eBig), School of Earth Sciences, Zhejiang University, Hangzhou 310027, China
Presenter Email: dinghe@zju.edu.cn |
| Dissolved organic matter (DOM) plays an important role in various biogeochemical processes. Thus, many investigations of DOM have been conducted in several aquatic ecosystems. Here we report the distribution and composition characteristics of DOM, particularly on the molecular level for the first time, in dry-wet period in a tributary named Xiangxi Bay and mainstream of the Three Gorges Reservoir (TGR), the largest reservoir in the world. A combined approach was conducted, including ion chromatography, UV absorbance spectroscopy, excitation and emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS).
The results showed both significant spatial and temporal variations of DOM in TGR. The compensation from mainstream to Xiangxi Bay was observed in dry period, which mainly controlled the distribution of hydrological gradients, resulting in the higher terrestrial and algal inputs but lower anthropogenic inputs in Xiangxi Bay than mainstream. No obvious spatial variability of DOM was observed in wet period. Additionally, the substantial effect on the quantity and quality of aquatic DOM in TGR resulted from the alterations of wet and dry periods were revealed. The origin differences such as the lower abiotic reactions inputs, higher algal inputs and the agricultural inputs in dry period were observed. Furthermore, DOM showed more terrigenous characteristics in wet period with a higher aromaticity and proportion of humic-like compounds than that in dry period. The positive correlation between aromaticity indices and DOM showed the influence of aromatic compounds on the DOM alterations, which suggest that the difference in terrigenous input caused by the anti-seasonal hydrological management made a major contribution to DOM seasonal dynamics in TGR. Thus, the spatial and temporal variations of DOM composition in TGR could be mainly caused by hydrogeological alterations and anthropogenic impacts, which illustrating the influence of dam construction on the fate of DOM and setting up a subtle insight into its further effect on global carbon cycle under the background of damming reservoirs booming all over the world. |
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