scholarly journals Characteristics and source tracing of organic carbon in intertidal sediments of wetland in Yangtze Estuary, China

2020 ◽  
Author(s):  
Haiyan Yu ◽  
Weiwei Li ◽  
Changxu Han ◽  
Han Fang ◽  
Xingquan Shu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Global Climate ◽  
Stable Carbon Isotope ◽  
River Estuary ◽  
Suspended Particles ◽  
Mean Value ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
Marsh Vegetation

Abstract Background: Wetland ecosystem is characterized by water-land interaction and plays an important role in regional energy and material circulation. In the context of global climate change, the study of wetland carbon storage and carbon cycle has become a focus of academic attention. The characteristics of organic carbon in sediments and its source is a key problem in the study of carbon cycle in wetlands. Results: In this study, the characteristics of total organic carbon (TOC), total nitrogen (TN) accumulation, and stable carbon isotope (δ13C) in the vegetation and soil were investigated for the three dominant salt marsh vegetation Phragmites australis (PA), Spartina alterniflora (SA), Scirpus mariqueter (SM) of the coastal wetlands of Chongming Dongtan in the Yangtze River Estuary. The results showed that the mean value of TOC and TN concentrations in the surface sediments of wetland were 1.39 ± 0.34% and 0.091± 0.024%, respectively. The carbon stable isotope (δ13C) mean value of sediment was -24.17±1.51‰. The TOC of the sediment in the three saltmarsh plant communities was in the order of SA (1.76 ± 0.38%) > PA (1.45 ± 0.37%) > SM (0.96 ± 0.44%). The simulation results of the three end-member mixing equations showed that the organic carbon in sediments was mainly derived from suspended particles (42.44 ± 20.89%) and vegetation (34.50 ± 25.23%). The contribution rate of microalgae is lower (23.06 ± 4.62%). Conclusion: The organic carbon in sediments of wetland in Yangtze Estuary are the result of mixed input of terrestrial organic carbon and marine organic carbon. Organic carbon in sediments was mainly derived from suspended particles and vegetations. The results provide preliminary knowledge of the distribution and sources of sedimentary organic carbon for better understanding the sediment transport and deposition in this region.

Morphodynamic Simulation at the South Branch of Yangtze Estuary

2009 ◽  
Author(s):  
Xiaoyan Zhou ◽  
Ulrich Zanke ◽  
Yixin Yan ◽  
Jinhai Zheng
Keyword(s):  
Yangtze River ◽  
Morphological Changes ◽  
River Estuary ◽  
Wave Model ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
The South ◽  
Morphological Response ◽  
The Yangtze River Estuary

In this paper a numerical morphodynamic model TIMOR3 has been introduced and applied to simulate the morphological response to the water and sediment changes in the Yangtze River Estuary. TIMOR3, coupled with Hydrodynamic Model and Wave Model, is used to simulate a long-term and huge area of the morphological changes in the Yangtze River Estuary. A detailed investigation was made to the south branch where the Deepwater Channel Navigation Project is under construction. The effect of the project in different phases with different water depth has been simulated and analyzed.

scholarly journals Changes in mangrove extension at the Pacoti River estuary, CE, NE Brazil due to regional environmental changes between 1958 and 2004

2007 ◽  
Vol 7 (3) ◽  
pp. 67-72 ◽  
Author(s):  
Luiz Drude de Lacerda ◽  
Marcelo Oliveira Teles de Menezes ◽  
Maurício Mussi Molisani
Keyword(s):  
Climate Changes ◽  
Environmental Changes ◽  
Global Climate ◽  
Land Use Changes ◽  
Sediment Accumulation ◽  
River Estuary ◽  
Drastic Reduction ◽  
Marsh Vegetation ◽  
Global Climate Changes ◽  
Regional Land

Regional land use changes at the Pacoti River basin, Ceará State, NE Brazil resulted in doubling the mangrove area from 1958 (0.71 km²) to 2004 (1.44 km²). Most of the increase was due to the replacing of salt marsh vegetation inland, but also along newly formed islands and enlarged river banks. Drastic reduction in freshwater supply and sediment accumulation due to river damming were probably the major drivers of the increased mangrove cover. However, changes due to global climate changes can not be ruled out.

scholarly journals Ecosystem Organic Carbon Stock Estimations in the Sile River, North Eastern Italy

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 80
Author(s):  
Alessandro Buosi ◽  
Yari Tomio ◽  
Abdul-Salam Juhmani ◽  
Adriano Sfriso
Keyword(s):  
Ecosystem Services ◽  
Organic Carbon ◽  
Carbon Cycle ◽  
Carbon Stock ◽  
Global Climate ◽  
River Ecosystem ◽  
Ecosystem Monitoring ◽  
River Ecosystems ◽  
North Eastern ◽  
Global Carbon

River ecosystems are one of the dynamic components of the terrestrial carbon cycle that provide a crucial function in ecosystem processes and high value to ecosystem services. A large amount of carbon is transported from terrestrial to the ocean through river flows. In order to evaluate the contribution of Sile River ecosystem to the global carbon stock, the river ecosystem Organic Carbon (OC) stock was quantified for sediments and dominant submerged aquatic macrophytes (SAMs) during the two sampling periods at three different stations along the Sile River (North Eastern Italy). The total mean ecosystem OC stock was 95.2 ± 13.8 Mg C ha−1 while those of SAMs ranged from 7.0 to 10.9 Mg C ha−1 which accounted for approx. 10% of the total OC stock. The total aboveground biomass retains approx. 90% of the SAM carbon stock, with a mean of 8.9 ± 1.6 Mg C ha−1. The mean sediment OC stock was 86.6 ± 14.5 Mg C ha−1 with low seasonal variations among the sites. Indeed, various environmental parameters and hydrodynamics appear to affect the accumulation of OC within the river ecosystem. The results highlight the role that freshwater river ecosystems play in the global carbon cycle, which consequently provide a baseline for future river ecosystem monitoring programs. Furthermore, future studies with additional sites and seasonal surveys of the river will enhance our understanding of the effects of global climate change on the river ecosystem and improve the ecosystem services.

scholarly journals GDGT distributions on the East Siberian Arctic Shelf: implications for organic carbon export, burial and degradation

2015 ◽  
Vol 12 (12) ◽  
pp. 3753-3768 ◽  
Author(s):  
R. B. Sparkes ◽  
A. Doğrul Selver ◽  
J. Bischoff ◽  
H. M. Talbot ◽  
Ö. Gustafsson ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Arctic Ocean ◽  
Coastal Erosion ◽  
Stable Carbon Isotope ◽  
Arctic Shelf ◽  
The Arctic ◽  
Fluvial Erosion ◽  
Siberian Arctic ◽  
The Arctic Ocean

Abstract. Siberian permafrost contains a globally significant pool of organic carbon (OC) that is vulnerable to enhanced warming and subsequent release into the contemporary carbon cycle. OC release by both fluvial and coastal erosion has been reported in the region, but the behaviour of this material in the Arctic Ocean is insufficiently understood. The balance between OC deposition and degradation on the East Siberian Arctic Shelf (ESAS) influences the climate–carbon cycle feedback in this area. In this study we couple measurements of glycerol dialkyl glycerol tetraethers (GDGTs) with bulk geochemical observations to improve knowledge of the sources of OC to the ESAS, the behaviour of specific biomarkers on the shelf and the balance between delivery and removal of different carbon pools. Branched GDGT (brGDGT) concentrations were highest close to river mouths, yet low in "ice complex" permafrost deposits, supporting recent observations that brGDGTs are mostly delivered by fluvial erosion, and may be a tracer for this in complex sedimentary environments. BrGDGT concentrations and the branched and isoprenoidal tetraether (BIT) index reduced quickly offshore, demonstrating a rapid reduction in river influence. Stable carbon isotope ratios changed at a different rate to the BIT index, suggesting not only that OC on the shelf is sourced from fluvial erosion but also that erosion of coastal sediments delivers substantial quantities of OC to the Arctic Ocean. A model of OC export from fluvial, coastal and marine sources is able to recreate the biomarker and bulk observations and provide estimates for the influence of fluvial and coastal OC across the whole shelf. The model shows that coastal erosion delivers 43 % of the OC and 87 % of the mineral sediment to the ESAS, but that rivers deliver 72 % of brGDGTs, indicating that brGDGTs can be used as a proxy for river-derived sediment.

Numerical study on the effect of edge scouring on stability of soft mattress in the Yangtze estuary

2021 ◽  
Author(s):  
Aofei Ji ◽  
Peng Hu ◽  
Zhiguo He ◽  
Fengfeng Gu
Keyword(s):  
Flow Structure ◽  
Numerical Study ◽  
Water Channel ◽  
River Estuary ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
The Yangtze Estuary ◽  
Bed Erosion ◽  
Physically Based ◽  
Depth Increase

<p><strong>Abstract: </strong>In the Yangtze River Estuary deep-water channel regulation project, soft mattresses have been widely used to reduce bed erosion and thus improve stability of bridges/piers/levees/dikes. However, soft mattresses are also subject to failure due to the continuous and gradual scour in their edges, which have been a major risk for their stability. Here we report a preliminary numerical study on this issue. Firstly, a depth-averaged two-dimensional hydro-sediment-morphodynamic model is applied to simulate edge scour process for the submerged dike of the Jiangyanansha in the Yangtze estuary. For this purpose, physically-based sediment erosion parameterization is proposed to take account of the effect of the soft mattresses. Compared with the inner area of the soft mattress, only the edge area has stronger erodibility. Numerical comparative studies indicate that a scouring pit may develop to the vicinity of the submerged dike without the protection of the soft mattress, whereas under the protection of the soft mattress, the scouring pit can be largely controlled. Nevertheless, as the scouring process continues, the pit region and depth increase, which may finally lead to failure of the soft mattress. Finally, full 3D high-resolution simulations of the near-bed flow structure with/without edge scour are conducted using flow3D to shed light on the failure mechanisms of the soft mattresses.</p><p><strong>Keywords:</strong> submerged dikes, soft mattress, erodibility, Yangtze estuary, edge scour, flow structure</p>

Photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary: kinetics and effects of temperature, pH, and salinity

2017 ◽  
Vol 19 (6) ◽  
pp. 861-873 ◽  
Author(s):  
Guisheng Song ◽  
Yijie Li ◽  
Suzheng Hu ◽  
Guiju Li ◽  
Ruihua Zhao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Yangtze River ◽  
River Estuary ◽  
Yangtze Estuary ◽  
Chromophoric Dissolved Organic Matter ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
The Yangtze Estuary ◽  
The Yangtze River Estuary ◽  
Effects Of Temperature

CDOM photobleaching in the Yangtze estuary is affected by its source, and water temperature and pH but not salinity.

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