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The ocean is the largest active carbon reservoir on Earth. Organic carbon (OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study, sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea, Yellow Sea, and East China Sea (BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr−1. Among them, the burial flux of biospheric OC is 6.92 Mt C yr−1, equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO2, indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment, while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas. [ABSTRACT FROM AUTHOR]

Coastal mud belts, which lie parallel to the coast just seaward of the shoreface, are one of the most important settings where shallow‐marine muddy deposits accumulate. However, sedimentary processes and facies distributions of coastal mud belts remain largely uninvestigated. This study uses process‐oriented sedimentology, coupled with provenance analysis and organic geochemistry of sedimentary records at the northern entrance to the Taiwan Strait, to investigate one of the largest such systems in the world, the Changjiang coastal mud belt. Carbon‐14 dates indicate that deposition has been intermittent throughout Marine Isotope Stages 1, 2 and 3, with several cryptic gaps in the muddy succession as a result of exposure or transgressive erosion during periods of lower or rising sea level, respectively. The palaeowater depth of each depositional unit was roughly estimated based on a global sea‐level curve and the elevation and age of the depositional units. Integrated provenance and sedimentology studies suggest that an incised valley most likely cut by the Minjiang, a nearby river draining the Chinese mainland, probably during Marine Isotope Stage 6, was filled with shelf mud during Marine Isotope Stage 3. These results demonstrate that deposition of mud on the Changjiang coastal mud belt was influenced by sea‐level changes that controlled water depth and flow patterns through Taiwan Strait. The Changjiang coastal mud belt migrates landward when sea level rises and moves seaward when sea level drops. In addition, changes in oceanic circulation associated with opening and closing of Taiwan Strait due to sea‐level changes causes significant changes in the source of the mud, with an alternation between sediment contributions from the Changjiang in the north, the nearby Minjiang, and the island of Taiwan to the south‐east. This study also reveals that the Changjiang coastal mud belt deposits are composed of both shallower‐water and deeper‐water facies. The shallower‐water facies predominantly comprises abundant fluid‐mud beds generated by waves and tidal currents. The deeper‐water facies contains shell‐rich mud and bioturbated mud, which were likely deposited by the Chinese coastal current and Taiwan Warm current. The bed types and interpretation of sedimentary processes of the Changjiang coastal mud belt are useful for recognition of ancient deposits of coastal mud belts elsewhere. [ABSTRACT FROM AUTHOR]

Arctic sea ice retreat is linked to extrapolar thermal energy import, while the potential impact of pan-Arctic river heat discharge on sea-ice loss has been unresolved. We reconstructed the Holocene history of Arctic sea ice and Russian pan-Arctic river heat discharge, combining ice-rafted debris records and sedimentation rates from the East Siberian Arctic Shelf with a compilation of published paleoclimate and observational data. In the mid-Holocene, the early summer (June–July) solar insolation was higher than that during the late Holocene, which led to a larger heat discharge of the Russian pan-Arctic rivers and contributed to more Arctic sea ice retreat. This intensified decline of early-summer sea ice accelerated the melting of sea ice throughout the summertime by lowering regional albedos. Our findings highlight the important impact of the larger heat discharge of pan-Arctic rivers, which can reinforce Arctic sea-ice loss in the summer in the context of global warming. Based on marine multiproxy records, a new study outlines the role of larger heat discharge of the pan-Arctic Rivers in determining the pronounced sea ice retreat over the East Siberian Arctic Shelf in the mid-Holocene. [ABSTRACT FROM AUTHOR]

Hyperpycnal flows are important agents for transporting detrital sediments from rivers to oceans. Previous studies often assumed that the deposits of flood‐controlled delta fronts would be dominated by graded sand with common hummocky cross‐stratification. This study documents, for the first time, hybrid event beds and plumite deposits inside the succession of a modern delta front. This delta in the Taiwan Strait is fed by the Choshui River, which is considered a highly efficient sediment transport system with individual floods with extremely high suspended sediment concentrations. The deltaic event beds recorded in the core were interpreted as hyperpycnal flow‐generated hybrid event beds and turbidites triggered by hypopycnal flows. Accelerator Mass Spectrometry 14C dating, grain‐size analysis and measurements of stable isotopic composition of organic matter were conducted to delineate the depositional process of the recognized beds. The internal subdivisions of the hybrid event beds were differentiated mainly based on sedimentary textures, including cohesive mud content, sand content and sorting. The disorganized portion (division H3) appears internally chaotic and contains large rafted substrate clasts but also displays an upward increase in dispersed cohesive mud from 35% (division H3a) to 50% (division H3b). In contrast, massive H1 divisions are characterized by much lower cohesive mud of ca 8%. The vertical arrangement between depositional facies allows the discrimination of three hybrid event bed types. The stable carbon isotopic composition of the organic matter reveals that the cohesive mud in each division of the hybrid event beds was sourced from marine substrate, rather than supplied by the original hyperpycnal flows. Therefore, the hybrid event beds are generated by energetic hyperpycnal flows, which can delaminate the muddy sea‐floor and incorporate large quantities of substrate fragments. The bulking of erosional hyperpycnal turbulent flow forces flow transformation and generates a more cohesive flow with a turbulent, dense head and trailing bipartite debris flow. The occurrence of hybrid event beds in modern shallow delta front settings is also an important novelty, implying a high density of hyperpycnal flows at the mouth of sediment‐laden rivers as well as the crucial impact of substrate entrainment on the development of hybrid event beds. [ABSTRACT FROM AUTHOR]

Carbon cycling in the tropical margin is more extensive compared with other regions of the world. The goal of this study was to better understand the origins, transport, and burial of sedimentary organic matter (SOM) in the Gulf of Thailand (GOT) from the coastal margin of Southeast (SE) Asia, which serve as a major depository of fine‐grained sediments and the associated organic carbon (OC). The results revealed a variety of organic matter (OM) inputs and the selective transport of fine sediment, resulting in preferential dispersal of terrigenous SOM in the GOT. Bulk OC indices with low carbon/nitrogen ratios and enriched stable carbon isotope ratios (−24.2‰ to −20.4‰, and mean −21.4 ± 0.56‰) are likely related to the presence of marine‐derived OM and anthropogenic interference. A binary mixing model further clarified the significant contributions of terrestrial derived‐OM within the upper and central GOT. The n‐alkane compositions and principal component analysis indicated that a majority of the terrigenous SOM settles within the estuary in the upper GOT, while a selective dispersal of land‐based SOM through long‐distance transport toward the modern depocenter in the lower GOT. The characteristics of lower molecular weight n‐alkanes also suggest anthropogenic OM input from petroleum‐related contributions. Altogether, the depositional patterns and spatial heterogeneity of the SOM indicated by both the bulk and molecular signatures reveal the important roles of source variability and the selective dispersal of land‐based OM on the supply and accumulation of OC in the tropical coastal margin. Plain Language Summary: The accumulation and fate of sedimentary organic carbon (OC) in the tropical coastal system are significant components of the global carbon cycling. In order to elucidate the distribution and accumulation of organic matter (OM) in tropical regimes, this study first explored the concentration and composition of sedimentary OC based on the bulk and molecular‐level data, and then depicted the modern transport pattern of OM in the Gulf of Thailand (GOT). This study showed terrestrial input accounted for 5%–64% (20% ± 8% on average) of the OM and dominated in the upper GOT, the offshore depocenter in the northeastern GOT and north of Samui Island. Molecular composition of n‐alkanes and principal component analysis result showed that the hydrodynamic condition plays a significant role on the selective dispersal of terrigenous OM from the coastal region to the offshore depocenter. In addition, the contribution from petroleum‐derived OM is also revealed based on the molecular‐level evidences. The spatial heterogeneity of OM revealed the variability of the sources and hydrodynamic forces on accumulation and fate of OM in the tropical coastal margins Key Points: The bulk organic matter (OM) signals indicate spatial heterogeneity of various OM contributions to the Gulf of Thailand (GOT)The molecular‐level OM compositions suggest a selective dispersal of terrigenous sedimentary organic matter (SOM) toward fine sediment depocenter in the central GOTSource variability and hydrodynamic forces regulate the accumulation and fate of SOM in the tropical coastal margin [ABSTRACT FROM AUTHOR]

The East China Sea Shelf has an unusually wide and low gradient shelf, supplied from sediment‐charged rivers and large river delta systems, with bottom currents sweeping the sea floor and located in the path of strong typhoons. Sediment gravity flow deposits, including four hybrid event beds and a high density turbidite, are identified in a core from the mid‐shelf of the East China Sea. The hybrid event beds typically comprise three or two internal divisions from the base to the top: (i) H1, H3 and H5; or (ii) H3 and H5. Radiocarbon ages of the hybrid event beds were in the range of 3821 to 8526 yr bp. Based on correlation with surrounding cores, the hybrid events may have happened at any time between 1930 yr bp and 3890 yr bp. The δ13C values in hybrid event beds together with bathymetry data suggest local erosion on the shelf. The average δ13C value for the H1 division is similar to the H3 division in the hybrid event beds, implying that the organic matter in the H1 and H3 divisions may come from the same source area. Cross‐plots of upper continental crust normalized rare earth elements in the five units reveal that the sediment source of the four hybrid event beds and the turbidite was ultimately primarily from Korean rivers. Partial transformation from a moderate‐strength debris flow with the additional role of erosional bulking can explain occurrences of hybrid event beds on the East China Sea Shelf. The data indicate that hybrid sediment gravity flow deposits were sourced from intra‐shelf failures and subsequently transformed and deposited as hybrid event beds. The study shows that hybrid sediment gravity flows and turbidity currents may not necessarily indicate proximity to a major fluvial or deltaic system and that intra‐shelf sedimentation can be a sediment source. It is unlikely that the debris flows and turbidity currents were triggered by a hyperpycnal flow or tsunami, because both can carry continental and/or coastal signals which have not been recognized in the core. Typhoons are the probable triggering mechanism. [ABSTRACT FROM AUTHOR]

Generation, morphology, and distribution of authigenic minerals directly reflect sedimentary environment and material sources. Surface sediments were collected from the western Gulf of Thailand during 2011-2012, and 159 samples were analyzed to determine detrital minerals. Authigenic minerals, including siderite, pyrite, and glauconite, are abundant whereas secondary minerals, such as chlorite and limonite, are distributed widely in the study area. Siderite has a maximum content of 19.98 g/kg and appears in three types from nearshore to continental shelf, showing the process of forming-maturity-oxidation. In this process, the MnO content in siderite decreases, but FeO and MgO content increase. Colorless or transparent siderite pellets are fresh grains generated within a short time and widely distributed throughout the region; high content appears in coastal area where river inputs are discharged. Translucent cemented double pellets appearing light yellow to red are mature grains; high content is observed in the central shelf. Red-brown opaque granular pellets are oxidized grains, which are concentrated in the eastern gulf. Pyrite is mostly distributed in the central continental shelf with an approximately north-south strip. Pyrite are mainly observed in foraminifera shell and distributed in clayey silt sediments, which is similar to that in the Yangtze River mouth and the Yellow Sea. The pyrite in the gulf is deduced from genetic types associated with sulfate reduction and organic matter decomposition. Majority of glauconite are granular with few laminar. Glauconite is concentrated in the northern and southern parts within the boundary of 9.5° to 10.5°N and is affected by river input diffusion. The distribution of glauconite is closely correlated with that of chlorite and plagioclase, indicating that glauconite is possibly derived from altered products of chlorite and plagioclase. The KO content of glauconite is low or absent, indicating its short formation time. [ABSTRACT FROM AUTHOR]

This study focuses on sedimentary environmental changes offshore of Hangzhou Bay, East China, since the Late Quaternary. AMS C ages from core CJK10, lithologies, distribution of foraminifera, heavy minerals, and S and Cl elements show a fluvial terrace environment during ∼23.2-11.0 cal ka BP; a littoral to tidal-flat environment during 11.0-10.2 cal ka BP; and a shallow marine environment with a relatively low sedimentation rate (0.1-0.22 cm/a) since 4.3 cal ka BP. High depositional rates (∼1.6 cm/a) from 10.9 to 10.2 cal ka BP resulted from sufficient accommodation space created by rapid sea level rise from −44 m to −33 m, from high sediment delivery by local rivers, and effective trapping of sediments by tidal-flat vegetation. The rate of sea level rise was variable; relatively high from 10.9 to 10.6 cal ka BP (2.1 cm/a), and lower since 10.6 cal ka BP (1.2 cm/a). The Changjiang alongshore current crossed the Hangzhou Bay to form the mud wedge on the inner shelf of the East China Sea later than 9.4 cal ka BP. The CJK10 site was a tide-dominated shelf environment and experienced erosion from approximately 9.4-9.2 cal ka BP to 4.3 cal ka BP. The depositional hiatus was caused by the Changjiang alongshore current, which was relatively weak during 9.4-7.5 cal ka BP and increased in strength during ∼7.5-4 cal ka BP. From ∼4.3 cal ka BP, a large amount of sediment from the Changjiang River was partly deposited on the continental shelf of Hangzhou Bay with some transported southward. Therefore, this study clarifies the history of Changjiang-derived sediment dispersal and deposition, although a detailed record of the changes in the Changjiang alongshore current since 4.3 cal ka BP is difficult to obtain because of the scarcity of evidence. [ABSTRACT FROM AUTHOR]

Although the mid-late Holocene cold and dry event about 4000 years ago (the 4 ka event) has been observed almost globally, it was most prominent in terrestrial climate proxies from the lower latitudes. Here we evaluate the oceanic response to this event in terms of a Holocene sea surface temperature (SST) record reconstructed using the U index for Core B3 on the continental shelf of the East China Sea. The record reveals a large temperature drop of about 5°C from the mid-Holocene (24.7°C at 5.6 ka) to the 4 ka event (19.2°C at 3.8 ka). This mid-late Holocene cooling period in Core B3 correlated with (i) decreases in the East Asia summer monsoon intensity and (ii) the transition period with increased El Niño/Southern Oscillation activities in the Equatorial Pacific. Our SST record provides oceanic evidence for a more global nature of the mid-late Holocene climate change, which was most likely caused by a southward migration of the Intertropical Converge Zone in response to the decreasing summer solar insolation in the Northern Hemisphere. However, the large SST drop around Core B3 indicates that the mid-late Holocene cooling was regionally amplified by the initiation/strengthening of eddy circulation/cold front which caused upwelling and resulted in additional SST decrease. Upwelling during the mid-late Holocene also enhanced with surface productivity in the East China Sea as reflected by higher alkenone content around Core B3. [ABSTRACT FROM AUTHOR]

Holocene changes in fine-grained sediment supplies to the East China Sea outer shelf were uncovered, through the mineralogical and geochemical analysis of Core B3 in the East China Sea Distal Mud (ECSDM). Based on the lithology, accelerator mass spectrometry (AMS) 14C dating, and sea-level change, Core B3 can be divided into two major units: transgressive stage (Unit 1: 12.5–6.8 kyr) and highstand stage (Unit 2: 6.8–0 kyr). Significant discrepancy of dolomite/calcite ratio in the fine fractions (<16 µm) of Changjiang (dolomite/calcite = 3:1) and Huanghe (dolomite/calcite = 1:22) sediments was used as a new uniqueness provenance tracer to distinguish these two riverine sources. Both of the dolomite/calcite ratio and rare earth elements fractionation parameters in the fine-grained sediment indicated distinct provenance shifts of Core B3 during the Holocene. Unit 1 of Core 3 (12.5–6.8 kyr) mainly consists of the reworked and resuspension sediments of the East China Sea shelf during the Holocene transgression, while Unit 2 sediments (6.8–0 kyr) are most likely sourced from the Changjiang and Huanghe. Moreover, mixing curves of dolomite/calcite ratio reveal that the ECSDM continuously received the Changjiang sediment since 6.1 kyr with notable fluctuations, whereas the Huanghe sediment supply began in 6.8 kyr but abruptly stopped during 4.2–0.8 kyr and then appeared again since 0.8 kyr. Temporal changes of the Changjiang and Huanghe fine-grained sediment contribution to the ECSDM are closely related to the formation of modern oceanic circulation system since 6.8 kyr (shelf sea-level change), the ‘4.2 kyr’ climate event, and the followed transition to cold and dry climate condition in the northeastern China (global climate change), as well as the artificial shift of lower Huanghe course in ad 1128 in the war against invasion of the northern nomadic nation (human activities). [ABSTRACT FROM AUTHOR]

The sedimentary facies of the subaqueous Changjiang (Yangtze) River delta since the late Pleistocene was studied based on lithology and foraminifera analysis for two boreholes, CJK07 and CJK11, along with C dating. Four sedimentary facies were identified, namely fluvial, tidal flat, offshore, and prodelta facies. The fluvial sedimentary facies is comprised of fluvial channel lag deposits, fluvial point bar deposits, and floodplain deposits, showing a fining-upward sequence in general with no benthic foraminifera. A layer of stiff clay overlies the fluvial deposits in core CJK07, indicating a long-term exposure environment during the Last Glacial Maximum (LGM). During the postglacial sea-level rise around 13-7.5 cal ka BP, the tidal flat facies was deposited in core CJK11, characterized by abundant silt-clay couplets. Euryhaline species dominate the subtidal flat foraminiferal assemblages, while almost no foraminifera was found in the intertidal flat. The offshore environment was the major sedimentary environment when the sea level reached its highest level around 7.5 cal ka BP, with a maximum accumulation rate of 10 mm/a found in core CJK11. Prodelta sediments have been deposited in core CJK11 since ∼3 cal ka BP, after the formation of the Changjiang River delta. The difference in sedimentary facies between core CJK07 and CJK11 is due to their location: core CJK07 was in an interfluve while core CJK11 was in an incised valley during the LGM. Furthermore, AMS 14 C dating of core CJK07 shows poor chronological order, indicating that the sediments were reworked by strong tidal currents and that sediment deposited since ∼7.7 cal ka BP in core CJK07 was eroded away by modern hydrodynamic forces caused by the southward shift of the Changjiang River delta depocenter. [ABSTRACT FROM AUTHOR]

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 AlO, FeO, MgO, NaO, KO, Cr, Cu, Mn, Ni, Pb, V, and Zn, and contain fine-grained sediments with mean grain size ( M)<22 μm; and; Regions II and IV contain mostly coarse-grained sediments, and are characterized by high concentrations of SiO, NaO, 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). [ABSTRACT FROM AUTHOR]

The Inductively Coupled Plasma Optical Emission Spectrometer was used to analyze sediment samples collected from the Hangzhou Bay to determine major and trace elemental concentrations. Based on these concentrations, the study area can be classified into three geochemical provinces. Province I covers the northern Hangzhou Bay area and contains high concentrations of AlO, FeO, MgO, NaO, KO, MnO, Cr, Cu, Ni, Pb, V, Co and Zn. Province III is located in the western Hangzhou Bay, near the Qiantang River mouth, and contains high concentrations of SiO, NaO, PO, TiO, Cr, Sr, Zr. Province II is located in the middle and eastern Hangzhou Bay, with the medium concentrations of major and trace elements. The results also demonstrate that the grain size is the dominating factor controlling the spatial variations of elemental concentrations, and the Changjiang River (Yangtze River) and Qiantang River sediments play an important role in the distribution of these elements. Anthropogenic impact on heavy metal concentrations (especially Cr, Sr and Zr) can be detected in the surface sediments near the Qiantang River mouth. [ABSTRACT FROM AUTHOR]

Located at the collision boundary between the Philippine Sea Plate and the Eurasian Continental Plate, the island of Taiwan is generally recognized as an important example in the MARGINS Program Science Plan and 'source-to-sink' research because of its high tectonic activity, heavy rainfall and unique geography. Large suspended sediment loads are transported to the adjacent ocean by Taiwanese rivers every year, making Taiwan an important source of sediments into the adjacent seas and a natural laboratory for studying the systemic movement of fluvial sediments from source to sink. A detailed study on the clay mineral composition of surface sediments collected from the drainage basins of 12 Taiwanese rivers using X-ray diffraction methods was conducted. Our results indicated that the clay mineral assemblages consisted dominantly of illite (approximately 73%) and chlorite (approximately 24%), with lesser abundances of kaolinite (approximately 3%) and even lower levels of smectite from the Danshuei River sediments in northwestern Taiwan. The Jhuoshuei River sediments from western Taiwan contained clay mineral assemblages that consisted of illite (approximately 75%) and chlorite (approximately 25%), but they lacked kaolinite and smectite. In southwestern Taiwan, the clay mineral assemblages were dominated by illite (approximately 75%) and chlorite (approximately 23%), but had a low abundance of kaolinite (generally < 2%) and no smectite. The clay mineral assemblages in eastern Taiwan are obviously different from those in western parts of the island. The most noticeable difference is that the average abundance of chlorite in the Hualien River from eastern Taiwan was the highest (approximately 48%) of all the Taiwanese rivers. We concluded that, in general, the clay mineral assemblages in Taiwanese rivers were mainly composed of illite and chlorite with kaolinite and smectite being scarce, and these trends are different from those in China's mainland rivers. The clay mineral composition shown in this study was primarily determined by the properties of the bedrock, and the differential weathering intensities of the drainage area. The surface sediments in Taiwan's rivers showed a greater abundance of illite and chlorite because the outcropped rocks were mainly composed of Tertiary sedimentary rocks, especially sandstone, shale and slate, and show strong physical weathering. The relatively high relief and more abundant rainfall also caused the clay minerals in the fluvial sediments to be transported to the estuaries down rivers from the mountains and then delivered to the adjacent seas by currents and waves over a shorter time scale. [ABSTRACT FROM AUTHOR]

AMS14C dating and analysis of grain size, major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea. Based on the environmentally sensitive grain size, clay mineral and major element assemblages, the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed. These three proxies, mean grain size (>9.71 µm), chemical index of alteration (CIA) and ratio of smectite to kaolinite in particular, show similar fluctuation patterns. Furthermore, 10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene; these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon. The cooling events correlated well with the results of the δ 18 O curves of the Dunde ice core and GISP2, which therefore revealed a regional response to global climate change. Four stages of the East Asia winter monsoon were identified, i.e. 8300-6300 a BP, strong and unstable; 6300-3800 a BP, strong but stable; 3800-1400 a BP, weak and unstable; after 1400 a BP, weak but stable. [ABSTRACT FROM AUTHOR]

Coastal vegetation not only mitigates the damage inflicted by marine disasters on coastal area, but also plays an important role in the global carbon cycle (i.e. blue carbon). Nevertheless, detailed records of both long-term changes in coastal vegetation composition and diversity, coupled with climate change and river evolution, remain sparse. To explore vegetation dynamics and their influencing factors on the coastal area of the Bohai Sea (BS) during the Holocene, in this study, we present high-resolution pollen and grain size data obtained from a sediment core of the BS. The results reveal that two rapid and abrupt changes in salt marsh vegetation are linked with the river-system changes. Within each event, a recurring pattern - starting with a decline in Cyperaceae, followed by an increase in Artemisia and Chenopodiaceae - suggests a successional process that is determined by the close relationship between Yellow River (YR) channel shifts and the wetland community dynamics. The phreatophyte Cyperaceae at the base of each sequence indicate lower saline conditions. Unchannelized river flow characterized the onset of the YR channel shift, caused a huge river-derived sediment accumulation in the floodplain, and destroyed the sedges in the coastal depression. Along with the formation of a new channel, lateral migration of the lower channel stopped, and a new intertidal mudflat was formed. Pioneer species (Chenopodiaceae, Artemisia) were the first to colonize the bare zones of the lower and middle marsh areas. In addition, the pollen results revealed that the vegetation in the Shandong Peninsula was dominated by broadleaved trees during the early Holocene (8500-6500aBP) and by conifers and broadleaved forests in the middle Holocene (6500-3500aBP), which was followed by an expansion of broadleaved trees (3500-1000aBP). After 1000aBP, human impacts are recognized as a sudden decrease in Quercus and a marked increase in secondary vegetation Pinus. The pollen-based temperature index indicated that a warmer early and late Holocene and colder middle Holocene were consistent with previously reported temperature records for North and Northwest China. The main driving factors of temperature variation in this region are insolation, greenhouse gases and the El Niño-Southern Oscillation. [ABSTRACT FROM AUTHOR]