The Experts below are selected from a list of 34920 Experts worldwide ranked by ideXlab platform
Ping Dong - One of the best experts on this subject based on the ideXlab platform.
-
Sedimentary Environment and formation mechanism of the mud deposit in the central south yellow sea during the past 40kyr
Marine Geology, 2014Co-Authors: Yonghong Wang, Weiguo Zhang, Ping DongAbstract:Abstract Sedimentary Environment and formation mechanism of the mud deposit in the central South Yellow Sea of China during the last 40 kyr are studied based on the analysis of particle size, sediment density, chemical features, magnetic properties and AMS 14 C ages of a new core YS01A together with other available core data. The results show that there exist four Sedimentary sections during this 40 kyr period, including two marine sections (A and C) and two terrestrial/intertidal sections (B and D). Sedimentary indexes of section D, which were formed before 40 kyr, show that strong weathering and erosion occurred in this section. In contrast, Sedimentary Environment of section B was wetter and warmer and weathering and erosion were not as strong as in section D. Marine deposits in both sections A and C indicated the effects of sea level rise and section C was deposited when the climate was much wetter than in section A. Variations of climate and local hydrodynamics created different sediment features of two marine sections. From the estimated river discharges of the Huanghe, Changjiang and relevant Korean rivers and calculation of mud deposit volumes of section A during the past 9.7 kyr, it is found that the sediment inputs from these river sources can only account for about 48% of sediments in the two mud deposits of the central and southeastern South Yellow Sea. The other main source of sediments is identified to be the seabed erosion, resuspension and redeposition from the Yellow Sea and, to a lesser extent, from the biogenesis and diagenesis. It provides a unique opportunity of understanding the formation and source of mud deposits by comparing the Sedimentary properties of sections A and C in core YS01A. It is found that formation of mud deposits is not related directly to the Yellow Sea Warm Current, which only changed the sediment properties of mud deposits in section A since it formed from Holocene by bringing a large amount of organic mass and finer particles. However, cold water mass developed in this area is important as it helped to trap more and finer particles in the two marine sections. Upwelling usually occurs around 50 m bathymetry which is at the juncture of two opposite water currents and has induced the thickest sediment layer. This study also confirmed that formation of the mud deposit in the central South Yellow Sea is caused mainly by the tidal currents on the continental shelves.
Yue Liu - One of the best experts on this subject based on the ideXlab platform.
-
impacts of land reclamation on sediment transport and Sedimentary Environment in a macro tidal estuary
Estuarine Coastal and Shelf Science, 2020Co-Authors: Zhixin Cheng, Isabel Jalonrojas, Xiao Hua Wang, Yue LiuAbstract:Abstract During the past decades, extensive coastal areas have been reclaimed along the coastline of China, while the physical mechanisms of human pressures on estuarine-sedimentation are largely unknown. This study investigates the impacts of a land reclamation activity on estuarine sedimentation in the Yalu River Estuary (YE), China. For this purpose, we perform a multidisciplinary approach that combines rare earth element (REE) sediment records and numerical simulations. REE pattern of two sediment core samples from the main estuarine branch changed from diverse to homogenous after the early 1970s, which indicates that the estuarine Sedimentary Environment experienced dramatic change after the land reclamation activity completed in 1975. In order to explore physical drivers behind this change, hydro-Sedimentary dynamics were simulated using Finite Volume Coastal Ocean Model (FVCOM) and an improved Track Marine Plastic Debris (TrackMPD) models. After the land reclamation, model results show that: (1) the degree of flood dominance decreased, and the tidal-choking effect was enhanced in the main branch. (2) The estuary became more well-mixed due to the stronger tidal current; (3) Suspended-sediment concentration (SSC), especially SSC in the bottom layer was increased. (4) The landward sediment flux caused by tidal pumping decreased significantly and the YE may turn into a sediment source instead of a sink if more land is reclaimed in the future. Furthermore, sediments in the main branch were likely from different sources before reclamation but became a homogenous mixture afterwards. This study qualitatively demonstrates the human-induced impacts on estuarine sedimentation using a multidisciplinary method.
Shu Jiang - One of the best experts on this subject based on the ideXlab platform.
-
effect of Sedimentary Environment on the formation of organic rich marine shale insights from major trace elements and shale composition
International Journal of Coal Geology, 2019Co-Authors: Luchuan Zhang, Dianshi Xiao, Shu JiangAbstract:Abstract Sedimentary Environment and redox conditions play a significant role in the formation of organic-rich shale. The vertical variations of major/trace elements, TOC (total organic carbon) and mineral compositions were investigated for the Lower Silurian Longmaxi typical marine shale in the Upper Yangtze Platform, South China, to decipher Sedimentary Environment (redox conditions, detrital input, sedimentation rate (SR), paleoproductivity and watermass restriction). This gives insight to the effects of variations in Sedimentary Environment on the formation of organic-rich shale. The results show that the Lower Longmaxi Formation is composed of three systems tracts: TST (transgressive systems tract), EHST (early highstand systems tract) and LHST (late highstand systems tract). From TST to LHST, the contents of TOC, quartz and pyrite decline steadily, whereas clay minerals and carbonate show an increasing trend. Thus, organic-rich siliceous (ORSS), organic-moderate mixed (OMMS) and organic-lean argillaceous (OLAS) shales are dominant for TST, EHST and LHST, respectively. Due to a continues fall of the relative sea-level, a deep-water shelf Environment with anoxic condition, high paleoproductivity and low detrital input in TST gradually evolves into a semi-deep-water Environment with dysoxic-oxic conditions, moderate paleoproductivity, and moderate detrital influx in EHST, further to an Environment of oxic condition, low paleoproductivity, and high detrital flux in LHST. As evidenced by Mo-TOC and Mo U patterns, ORSS was deposited in a moderately restricted watermass, weaker than Black Sea, which progressively evolved into an enhanced restriction degree during the deposition of OMMS and OLAS due to a fall of relative sea-level. Major/trace elements and excess silica (EX-SiO2) concentrations illustrate that origins of quartz in the Lower Longmaxi shale are primarily terrigenous, biogenic and authigenic (smectite illitization). The average proportions of EX-SiO2 (biogenic and authigenic quartz) are 52.34%, 24.86% and 6.57% for ORSS, OMMS and OLAS, respectively. Biogenic quartz is the dominant contributor to EX-SiO2, while the contribution of authigenic quartz is limited, and the formation of the former is earlier than the latter according to the diagenetic transformation temperature. As both biogenic quartz and organic matter are firmly related to the abundance and preservation of paleoorganisms, anoxic condition, high paleoproductivity, low detrital flux and moderate restriction collectively control the high enrichment and preservation of organic matter and biogenic quartz, while oxic condition, low paleoproductivity, high detrital flux and stronger watermass restriction are unfavorable for the enrichment of biogenic quartz and organic matter.
Isabel Jalonrojas - One of the best experts on this subject based on the ideXlab platform.
-
impacts of land reclamation on sediment transport and Sedimentary Environment in a macro tidal estuary
Estuarine Coastal and Shelf Science, 2020Co-Authors: Zhixin Cheng, Isabel Jalonrojas, Xiao Hua Wang, Yue LiuAbstract:Abstract During the past decades, extensive coastal areas have been reclaimed along the coastline of China, while the physical mechanisms of human pressures on estuarine-sedimentation are largely unknown. This study investigates the impacts of a land reclamation activity on estuarine sedimentation in the Yalu River Estuary (YE), China. For this purpose, we perform a multidisciplinary approach that combines rare earth element (REE) sediment records and numerical simulations. REE pattern of two sediment core samples from the main estuarine branch changed from diverse to homogenous after the early 1970s, which indicates that the estuarine Sedimentary Environment experienced dramatic change after the land reclamation activity completed in 1975. In order to explore physical drivers behind this change, hydro-Sedimentary dynamics were simulated using Finite Volume Coastal Ocean Model (FVCOM) and an improved Track Marine Plastic Debris (TrackMPD) models. After the land reclamation, model results show that: (1) the degree of flood dominance decreased, and the tidal-choking effect was enhanced in the main branch. (2) The estuary became more well-mixed due to the stronger tidal current; (3) Suspended-sediment concentration (SSC), especially SSC in the bottom layer was increased. (4) The landward sediment flux caused by tidal pumping decreased significantly and the YE may turn into a sediment source instead of a sink if more land is reclaimed in the future. Furthermore, sediments in the main branch were likely from different sources before reclamation but became a homogenous mixture afterwards. This study qualitatively demonstrates the human-induced impacts on estuarine sedimentation using a multidisciplinary method.
Peter M. J. Herman - One of the best experts on this subject based on the ideXlab platform.
-
impacts of bottom and suspended cultures of mussels mytilus spp on the surrounding Sedimentary Environment and macrobenthic biodiversity
Helgoland Marine Research, 2009Co-Authors: Tom Ysebaert, Miron Hart, Peter M. J. HermanAbstract:The aim of this study was to quantify the effect of bottom and suspended mussel cultures, cultured in different physical Environments, on the Sedimentary Environmental conditions and thereby the biodiversity structure of the associated macrofaunal community. We compared two bottom cultures (Limfjorden: microtidal, wind-driven; Oosterschelde: macrotidal) and one suspended culture (Ria de Vigo in an upwelling coastal region). The Sedimentary Environmental conditions (mud fraction, POC, PON, phosphorus content, chl a breakdown products) were significantly elevated underneath and surrounding bottom and suspended cultures compared to culture-free sediments that were nearby and hydrodynamically similar. The relative change in Environmental conditions was more pronounced in the Oosterschelde compared to Limfjorden, most likely due to differences in hydrodynamic forcing and characteristics of the mussel bed. The effect of the suspended cultures in Ria de Vigo on the surrounding sediments was influenced by local topographic and hydrodynamic conditions. The impact of mussels on the benthic community due to biodeposition was clearly seen in the community structure. The species composition changed from species which are typically present in sandy Environments to more small opportunistic species, which are typically present in organically enriched sediments. The impact of bottom cultures on the benthic community due to changes in the habitat under the presence of mussels was positive, especially in the Oosterschelde where an increase in the number of epibenthic species was seen. The influence of bottom cultures on the Sedimentary Environment and on the macrobenthic community seems to be very local. Within the mussel site in Limfjorden, differences were detected between sites where none or almost no mussels were present with sites where mussels were very abundant.
-
Impacts of bottom and suspended cultures of mussels spp. on the surrounding Sedimentary Environment and macrobenthic biodiversity
Helgoland Marine Research, 2008Co-Authors: Tom Ysebaert, Miron Hart, Peter M. J. HermanAbstract:The aim of this study was to quantify the effect of bottom and suspended mussel cultures, cultured in different physical Environments, on the Sedimentary Environmental conditions and thereby the biodiversity structure of the associated macrofaunal community. We compared two bottom cultures (Limfjorden: microtidal, wind-driven; Oosterschelde: macrotidal) and one suspended culture (Ria de Vigo in an upwelling coastal region). The Sedimentary Environmental conditions (mud fraction, POC, PON, phosphorus content, chl breakdown products) were significantly elevated underneath and surrounding bottom and suspended cultures compared to culture-free sediments that were nearby and hydrodynamically similar. The relative change in Environmental conditions was more pronounced in the Oosterschelde compared to Limfjorden, most likely due to differences in hydrodynamic forcing and characteristics of the mussel bed. The effect of the suspended cultures in Ria de Vigo on the surrounding sediments was influenced by local topographic and hydrodynamic conditions. The impact of mussels on the benthic community due to biodeposition was clearly seen in the community structure. The species composition changed from species which are typically present in sandy Environments to more small opportunistic species, which are typically present in organically enriched sediments. The impact of bottom cultures on the benthic community due to changes in the habitat under the presence of mussels was positive, especially in the Oosterschelde where an increase in the number of epibenthic species was seen. The influence of bottom cultures on the Sedimentary Environment and on the macrobenthic community seems to be very local. Within the mussel site in Limfjorden, differences were detected between sites where none or almost no mussels were present with sites where mussels were very abundant.
