MONITORING THE DIFFUSION OF SUSPENDED SEDIMENTS AND STABILITY OF TIDAL RADIAL SAND RIDGES AREA USING MULTI-SATELLITE REMOTE SENSING DATA

Nine Landsat TM tapes and images and MSS images, 10 NOAA tapes and images and 1 SAR image from 1973 to 1997 were used to analyse the diffusion of suspended sediments and the change of tidal radial sand ridges in the northern part of the Changjiang River delta, the South Yellow Sea. The results showed that the diffusion of suspended sediments was controlled by the tide, net current, and submarine topography in this area. The distribution of suspended sediments had close relationship with thesubmarine topography. The old Huanghe River delta and the Changjiang River comprise the main sediment supply for the formation of radial sand ridges, whose evolution can be divided into three stages since the Huangbe River changed its course and flowed northward into the Bohai Sea.     

Study on suspended matter in seawater in the Southern Yellow Sea

Distribution of suspended matter in seawater in the Southern Yellow Sea is investigated in five regions: 1) the Northern Jiangsu bank, the highest TSM (total suspended matter) content region; 2) the high TSM content region off the Changjiang River mouth; 3) the high TSM content region off the Chengshan Cape; 4) the low TSM region off Haizhou Bay; 5) the central part of the Southern Yellow Sea, a low TSM content region. The vertical distribution of TSM is mainly characterized by a spring layer of suspended matter, written as “suspended-cline” whose genesis is related to storms in winter. In this paper, non-combustible components and grain sizes in suspended matter, relationship between suspended matter and bottom sediments, and salinity in seawater are described. Investigation result shows that, in this area, suspended matter comes mainly from resuspended bottom sediment and secondarily from present discharge loads from rivers and biogenic materials. Discharged sediments from the Huanghe River move around the Chengshan Cape and affect the northwestern region of this area. Sediments from the Changjiang River affect only the southern part and have little or no direct influence on the central deep region. Wave is the main factor affecting distribution of suspended matter. Water depth controls the critical depth acted on by waves. The cold water mass in the central region limits horizontal and vertical dispersions of terrigenous materials. Suspended matter here has the transitional properties of the epicontinental sea. Its concentration and composition are different from those of a semi-closed sea (such as the Bohai Sea) and those of the East China Sea outer continental shelf or those near oceanic areas.     

SEDIMENT DISCHARGE OF THE HUANGHE RIVER AND ITS EFFECT ON SEDIMENTATION OF THE BOHAI SEA AND THE YELLOW SEA

The Huanghe (Yellow) River, with annual sediment discharge about 11 ×108tons, contributes about 17% of the fluvial sediment discharge of world's 21 major rivers to the ocean because its middle reaches flow across the great Loess Plateau of China. Sediment discharge of the Huanghe River has a widespread and profound effect on sedimentation of the sea. The remarkable shift of its outlet in 1128-1855 A.D. to the South Yellow Sea formed a large subaqueous delta and provided the substrate for an extensive submarine ridge field.The shift of its outlet in the modern delta every 10 years is the main reason why with an extremely heavy sediment input and a micro- tidal environment, the Huanghe River has not succeeded in building a birdfoot delta like the Mississippi. The Huanghe River has consistently brought heavy sediment input to sea at least since 0.7 myr.B.P. Paleochannels, paleosols, cheniers and fossils on the sea bottom indicate that the Yellow Sea was exposed during the late Quaternary glacial low-sea l     

Onshore warm tongue and offshore cold tongue in the western Yellow Sea in winter: the evidence

A winter onshore warm tongue extending from the Yellow Sea Warm Current to the southern Jiangsu coast, and an of fshore cold tongue extending from the southern Jiangsu coast to the southwest of Jeju Island(South Korea), are newly identified based on the sea-surface temperature from satellite remote sensing, and further confirmed by the distribution of suspended sediments. In addition, there are two obvious thermal fronts associated with the onshore warm tongue and off shore cold tongue. The narrow gap between the two thermal fronts is supposed to be the pathway for the off shore transport of cold coastal water and suspended sediments. The concurrence of onshore warm and of fshore cold tongues suggests the concurrence of onshore and off shore currents in the western Yellow Sea in winter, which seems to be inconsistent with the previously accepted view that, in winter, the Yellow Sea Coastal Current flows from the Old Huanghe Delta to the southwest of Jeju Island. This distinctive phenomenon helps establish an updated view of the circulation in the western Yellow Sea in winter.     

Model of modern dynamic deposition in the east China Sea

Since the last rising of sea level, two branches of the Kuroshio, the Huanghai (Yellow Sea) coastal current (HCC; mainly cold water mass) and the Changjiang River outflow have controlled the modern dynamic deposition in the East China Sea. There are three depositing areas on the sea-bed under the above currents: a relict sand area un der the Taiwan Warm Current and the Huanghai Warm Current at the south-eastern area, the about 60 km² round mud bank under the Huanghai Coastal Current at the northern area and the large subaqueous delta of mainly fine sand and silt under the Changjiang discharge flow in its estuary and the large narrow mud bank under the Zhejiang-Fujian Coastal Current, another round mud bank under the Changjiang discharge flow off Hangzhou Bay. The relict sand area has a coarsesand block under the Taiwan Warm Current bypassing Taiwan at the northern part of the island. The two round mud banks were formed in relatively static states by an anticlockwise converging cyclonic eddy. The coarsesand block was formed by a clockwise diverging cyclonic eddy. This new dynamic deposition theory can be used to explain not only the dynamic deposition process of clay, but also the patchy distribution of sediments on the shelves of the world ocean s.     

Sedimentary evolution since the late Last Deglaciation in the western North Yellow Sea

To decipher the sedimentary evolution and environmental changes since the late Last Deglaciation, two gravity cores were analyzed from the western North Yellow Sea (NYS). The two cores (B-L44 and B-U35) were sampled for grain size, clay minerals, detrital minerals, and 14C dating. They are comparable in lithofaies, and the observed succession was divided into four depositional units based on lithology and mineral assemblages, which recorded the postglacial transgression. Depositional unit 4 (DU 4) (before 11.5 ka) was characterized with enrichment in sand, and was interpreted as nearshore deposits in shallow water during the Younger Dryas Event. DU 3 (11.5-9.6 ka) displayed a fining-upward succession composed of sediments from local rivers, such as the Huanghe (Yellow) River, and from coastal erosion, which clearly were related to the Early Holocene transgression. Stable muddy deposition (DU 2) in NYS began to form at about 9.6 ka, which received direct supply of fine materials from the Shandong subaqueous clinoform. It is believed that the Yellow Sea circulation system played a major role in controlling the formation of fine sediment deposition in DU 1 (after 6.4 ka) after the sea level maximum.     

Geochemical studies of U,Th, Ra,40K in seciments of the China Sea and adjacent sea area,and lower reaches of several Chinese Rivers

Geochemical studies of the U, Th, Ra, and⁴⁰K in surface sediments of the China Sea and adjacent sea areas, the lower reaches of the Huanghe and Changjiang Rivers and the estuaries of the Zhujiang and Rongjiang Rivers were carried out with a model 8180-4K multichannel Ge(Li)γ spectrometer in 1981–1985. The mean values of U, Ra, Th,⁴⁰K are about 2.11 ppm, 7.67×10⁻¹³g/g, 11.00 ppm, and 2.33 ppm respectively, in the China Sea, the Okinawa Trough, and the Changjiang and Huanghe River estuaries. The distribution of the four isotopes is uniform in the above zone. The contents of U and Th in the sediments of the Zhujiang and Rongjiang Rivers and the Fujian coast are 1–4 times higher than those of the above zone and are related to the granite and radioactive ore present in the upper reaches of these rivers or the adjacent mountains. The distributions of U, Th, Ra, and⁴⁰K are related to the physico-chemical property, redox state, geological type and grain size of the sediment, and biotic activity. Contribution No. 1408, Institute of Oceanology, Academia Sinica, Qingdao.     

The distribution and variation of elements in sediments off the Huanghe (Yellow) River mouth

Surface sediment samples collected off the Huanghe (Yellow) River mouth during the period 2007–2009 were analyzed for major and trace element concentrations. Concentrations of 16 elements were measured using X-ray fluorescence spectrometry. Results demonstrate that sediment grain size is the dominant factor controlling the spatial variations of elemental concentrations. Correlation and cluster analyses allowed classification of the study area into four geochemical regions: Regions I and III are characterized by high concentrations of Al₂O₃, Fe₂O₃, MgO, Na₂O, K₂O, Cr, Cu, Mn, Ni, Pb, V, and Zn, and contain fine-grained sediments with mean grain size (M _z)<22 μm; and; Regions II and IV contain mostly coarse-grained sediments, and are characterized by high concentrations of SiO₂, Na₂O, and Zr. The sediment entering the sea from the Huanghe River and its tributaries is enriched in Ca. Thus, the Ca/Al ratio was used as an indicator of the proportion of sediments in the study area that originated from the Huanghe River. Ca/Al ratios decrease from Regions I and II (located in the nearshore zone of the Huanghe River delta) to Regions III and IV (distributed in the offshore zone of the northern Huanghe River delta, southern and southeastern Laizhou Bay area).     

Sediment flux and source in northern Yellow Sea by^210 Pb technique

1 INTRODUCTION The Yellow Sea is a shallow epicontinental sea surrounded by Chinese mainland and Korean Peninsula. It is connected with the East China Sea to the south, and with the Bohai Sea to the north- west. Water depth is generally less than 80 m with average of 44 m (Qin et al., 1989). The major sediment sources are the Huanghe and Changjiang (Yangtze) Rivers, providing annual sediment load of about 1.1×109 and 4.9×108 tons, respectively. A maximum of 1.6×108 tons of sedime…     

Distribution of diatoms and silicoflagellates in surface sediments of the Yellow Sea and offshore from the Changjiang River,China

The spatial distribution of siliceous microfossils (diatoms and silicoflagellates) in the surface sediments was mapped at 113 sites in the Yellow Sea and sea areas adjacent to the Changjiang (Yangtze) River, China. In total, 267 diatom taxa and two silicoflagellate species were identified from the sediments. The spatial variations in abundance and diversity were classified into three distinct geographic patterns using Q mode clustering: a south-north geographic pattern, a coastal-offshore pattern and a unique pattern in the Changjiang River mouth. The south-north geographic pattern was related to the spatial variations in sea temperature. Coscinodiscus oculatus, a warm-water species, indicated these variations by a gradual decrease in abundance from the south to the north. The coastal-offshore pattern was in response to the spatial variations in salinity. Cyclotella stylorum, Actinocyclus ehrenbergii and Dictyocha messanensis, the dominant brackish species in coastal waters, significantly decreased at the isobaths of approximately 30 m, where the salinity was higher than 31. Paralia sulcata and Podosira stelliger indicated the impact of the Yellow Sea Warm Current in the central Yellow Sea. The unique pattern in the Changjiang River mouth showed the highest species diversity but lower abundance, apparently because: freshwater input can significantly increase the proportion of brackish species; nutrients can supply the growth of phytoplankton; and high sedimentation rates can dilute the microfossil abundance in the sediments. Our results show that an integration of environmental factors (e.g., nutrient levels, sedimentation rate, sea temperature, salinity and water depth) determined the spatial characteristics of the siliceous microfossils in the surface sediments.     

Centennial-scale records of total organic carbon in sediment cores from the South Yellow Sea,China

Global carbon cycling is a significant factor that controls climate change.The centennial-scale variations in total organic carbon(TOC)contents and its sources in marginal sea sediments may reflect the influence of human activities on global climate change.In this study,two fine-grained sediment cores from the Yellow Sea Cold Water Mass of the South Yellow Sea were used to systematically determine TOC contents and stable carbon isotope ratios.These results were combined with previous data of black carbon and (210)~Pb dating from which we reconstructed the centennial-scale initial sequences of TOC,terrigenous TOC(TOC_(ter))and marine autogenous TOC(TOC_(mar))after selecting suitable models to correct the measured TOC(TOC_(cor)).These sequences showed that the TOC_(ter) decreased with time in the both cores while the TOC_(mar) increased,particularly the rapid growth in core H43 since the late 1960s.According to the correlation between the Huanghe(Yellow)River discharge and the TOC_(cor),TOC_(ter),or TOC_(mar),we found that the TOC_(ter) in the two cores mainly derived from the Huanghe River and was transported by it,and that higher Huanghe River discharge could strengthen the decomposition of TOC_(mar).The newly obtained initial TOC sequences provide important insights into the interaction between human activities and natural processes.     

High resolution records of flood deposition in the mud area off the Changjiang River mouth during the past century

This paper presents a paleoflood study to determine the flood frequency of the Changjiang River, based on core cj0702, taken from the Changjiang River subaqueous delta. We identified flood deposits by means of high-resolution grain-size variation, sensitive population, geochemical indexes and magnetic susceptibility. The core covers a time span of 120 years by 210 Pb dating and was sampled at 1–2 cm intervals. Grain size, geochemical elements, and physical parameters were analyzed. The results indicate that the sediment of the core is mainly composed of silt and clay, as well as groups of interbedded silt, clay silt, and clay. Vertically, the grain size pattern was controlled by seasonal variations in water discharge and by the sediment input in winter from the abandoned Huanghe River delta. River flooding caused extreme values in all our measured parameters. We identified more than 20 flood events that occurred since 1887 using the physical parameter analysis method. The environmentally sensitive component of sediment grain size(14.32–96.39 μm) contribution30%, Zr/Rb ratio1.5, and magnetic susceptibility16 were selected as the criteria for flood identification generally. We also found that floods that had taken place in the upstream, midstream, or downstream parts of the river were clearly identified by these indexes while the large-scale floods that covered the whole drainage area did not leave clear indications in the sediment record. This study for identification of flood events is of great significance for understanding hyperpycnal current sedimentation as well as for forecasting of floods.     

Relocation of the Yellow River estuary in 1855 AD recorded in the sediment core from the northern Yellow Sea

Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855 AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/Al₂O₃, Cr/Al₂O₃, Ni/Al₂O₃ and Se/Al₂O₃ ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.     

THE DESTRUCTION OF ANCIENT ECOLOGICAL ENVIRONMENT AND THE MOVEMENT OF CIVILIZATION CENTER IN CHINA

China is one of the ancient civilization countries. Owing to the blind reclamation, the vegetation had been destroyed, causing soil erosion and desertification, and making the civilization center move to the Changjiang (Yangtze) River valley from the Huanghe (Yellow) River. This movement began in the Qin and Han dynasties (221 B.C-220 A.D.) because at that time the large-scale reclamation was felled, the grassland was reclaimed into farmland, the vegetation was seriously destroyed in the loess and north of the Huanghe River, and the climate was getting colder; and the turn from north to south occurred in the Sui and Tang dynasties (581-907 A.D.) and completed in the Song Dynasty (960-1279 A.D.). However, at present the vegetation damage of the Changjiang River valley is very serious too and the silt carrying capacity of the Changjiang River is increasing sharply; thus the Changjiang River is in danger of becoming a second Huanghe River, so we must pay attention to the protection of ecological environmen     

Provenance of Sediments Filling a Paleo-Channel that Formed on the Western Yellow Sea Continental Shelf During the Last Glacial Period

Several buried paleo-channels are located on the continental shelf of the western Yellow Sea. Research on the paleochannels is significant for both theoretical studies and practical applications. In this paper, we analyse and discuss the mineralogy of sediments in a core (SYS-0803) recovered from a buried paleo-channel on the continental shelf of the western Yellow Sea. The aim is to determine the provenance of sediments that fill the paleo-channel. The heavy mineral assemblage of sediments in the core consists of schistose minerals, common hornblende, epidote, and ilmenite. The light mineral assemblage consists of plagioclase, quartz, lithic fragments, and K-feldspar. Analysis of the compositional maturity of the sand fraction revealed a quartz/feldspar ratio of < 1. A relatively high percentage of smectite is recorded throughout the entire paleo-channel fill, with the greatest percentage in the middle to lower parts. The detrital mineral assemblage and clay mineral content indicate that the paleo-channel sediments were sourced mainly from the Huanghe River during the last glacial period.     

Features of clay minerals in the YSDP102 core on the continental shelf of the southeast Yellow Sea

Ninety-eight clay mineral samples from the YSDP102 core were analyzed by x-ray diffractometer to study the four clay minerals: illite, chlorite, kaolinite and smectite. Twenty-eight samples had been analyzed on the laser particle-siz eanalyzer to reveal the particle features of the sediments. Distribution of the clay minerals and the particle characteristics in the YSDP102 core show that the core experienced three different depositional periods and formed three different sedimentary intervals due to different sediment sources and different depositional environments. Features of the clay minerals and the heavy minerals in the YSDP102 core indicate that coarse-grained sediments and fine-grained sediments result from different sources. The Yellow Sea Warm Current has greatly influenced the sedimentary framework of this region since the current‘s formation.     

Century-scale high-resolution black carbon records in sediment cores from the South Yellow Sea,China

Black carbon(BC)has received increasing attention in the last 20 years because it is not only an absorbent of toxic pollutants but also a greenhouse substance,preserving fire-history records,and more importantly,acting as an indicator of biogeochemical cycles and global changes.By adopting an improved chemothermal oxidation method(WXY),this study reconstructed the century-scale high-resolution records of BC deposition from two fine-grained sediment cores collected from the Yellow Sea Cold Water Mass in the South Yellow Sea.The BC records were divided into five stages,which exhibited specific sequences with three BC peaks at approximately 1891,1921,and 2007 AD,representing times at which the first heavy storms appeared just after the termination of long-term droughts.The significant correlation between the times of the BC peaks in the cores and heavy storms in the area of the Huanghe(Yellow)River demonstrated that BC peaks could result from markedly strengthened sedimentation due to surface runof f,which augmented the atmospheric deposition.Stable carbon isotope analysis indicated that the evident increase in carbon isotope ratios of BC in Stage 5 might have resulted from the input of weathered rock-derived graphitic carbon cardinally induced by the annual anthropogenic modulation of water-borne sediment in the Huanghe River since 2005 AD.Numerical calculations demonstrated that the input fraction of graphitic carbon was 22.97% for Stage 5,whereas no graphitic carbon entered during Stages 1 and 3.The obtained data provide new and important understanding of the source-sink history of BC in the Yellow Sea.     

Change in Sediment Provenance Near the Current Estuary of Yellow River Since the Holocene Transgression

Sedimentary sequence and sediment provenance are important factors when it comes to the studies on marine sedimentation. This paper studies grain size distribution, lithological characteristics, major and rare earth elemental compositions, micropaleontological features and ~(14)C ages in order to examine sedimentary sequence and sediment provenance of the core BH6 drilled at the mouth of the Yellow River in Bohai Sea. According to the grain size and the micropaleontological compositions, 4 sedimentary units have been identified. Unit 1(0–8.08 mbsf) is of the delta sedimentary facies, Unit 2(8.08–12.08 mbsf) is of the neritic shelf facies, Unit 3(12.08–23.85 mbsf) is of near-estuary beach-tidal facies, and Unit 4(23.85 mbsf–) is of the continental lake facies. The deposits from Unit 1 to Unit 3 have been found to be marine strata formed after the Holocene transgression at about 10 ka BP, while Unit 4 is continental lacustrine deposit formed before 10 ka BP. The provenances of core BH6 sediments show properties of the continental crust and vary in different sedimentary periods. For Unit 4 sediments, the source regions are dispersed while the main provenance is not clear, although the parent rock characteristics of a few samples are similar to the Luanhe River sediments. For Unit 3, sediments at 21.1–23.85 mbsf have been mainly transported from the Liaohe River, while sediments above 21.1 mbsf are mainly from the Yellow River and partially from the Liaohe River. For Unit 2, the sediments have been mainly transported from the Yellow River, with a small amount from other rivers. For Unit 1, the provenance is mainly the Yellow River catchment. These results help in better understanding the evolution of the Yellow River Delta.     

Application of swat model in the upstream watershed of the Luohe River

1INTRODUCTIONIntheHuanghe(Yellow) Riverbasin, soilerosionisaseriousproblem,whilerunoffandsedimentyieldsim-ulation hasnotbeenextensivelystudiedonthebasisofGIS(GeographicInformationSystem) and dis-tributedhydrologicalmodel.Inthisstudy,theLushiwatershed,whichislocatedattheupstreamoftheLushiHydrologicalStationintheLuoheRiver—thebiggesttributary oftheHuanghe Riveranddown-streamofXiaolangdiDam,isselectedasthestudyarea.ThelevelofsoilerosioninLushiwatershedismoderatein theHuangheRiverbas…     

GEOCHEMICAL CHARACTERISTICS OF PHOSPHORUS NEAR THE HUANGHE RIVER ESTUARY

INTRODUCTIONPhosphorus (P)isanimportantlimitingelementinglobaloceanicproductivity (Holland ,1 978) ,soknowledgeofPisakeytobetterunderstandingofthecyclingofcarbon ,nitrogen,sulfur,andothernu trientelements.Inasimplemassbalancemodel,thelevelofdissolvedPintheoceanisafunctionoftherateofinputviarivers,andtherateofoutputviadepositioninsediments.Inthepresentstudy,thefocusisontheriverinePinputbytheHuangheRiver (YellowRiver)totheBohaiSea,andespeciallyontheamountofPsolubilizedfromsolidphasesupo…