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The major source of particulate matter in the East China Sea (ECS) is the Changjiang (Yangtze) River. Sediment types, the geochemical indices of terrigenous and biogenic inputs (TOC, CaCO 3 and Sc), and biomarker indices such as the carbon preference index (CPI) of long-chain n-alkanes and the cinnamyl/vanillyl ratio (C/V) in surface sediments, all reveal that the influence of terrestrial material initially declines away from the mouth of the Changjiang River across the ECS continental shelf. However, the influence then strengthens from the middle ECS shelf toward the continental slope and the Okinawa Trough, because when the northeast winds prevail from September to April, the Changjiang River plume flows southwestward along the coast of China. Part of this flow turns eastward in the northern Taiwan Strait, and then joins the northeastwardly flowing Kuroshio to reach the Okinawa Trough. As the central ECS is bypassed, the sediments accumulated there are geologically older, carbonate-rich and organic-poor than those found off the coast of China and in the Okinawa Trough. Between June and August, when southwest winds prevail, the Changjiang plume generally flows northeastward. Yet, strong cyclonic currents that are generated by typhoons that pass through the ECS move the suspended particulates and the resuspended sediments southwestward from the coast of China. The turbid water then turns toward Taiwan in the northern Taiwan Strait and joins the Kuroshio, before reaching the Okinawa Trough. Again, young sediments are transported to the Okinawa Trough without passing through the central ECS. [ABSTRACT FROM AUTHOR]

This paper presents the distribution of total phosphorus (P), inorganic P (IP) and organic P in sediment cores from Sishili Bay, China. Their concentrations (μmol g − 1 ) ranged from 15.04 to 21.59, 12.43 to 18.27 and 0.15 to 5.11, respectively, showing 87.6–96.9% of TP is IP. The distribution of the fractionation of IP , obtained by a sequential extraction technique, was 1.9–3.2% for soluble and loosely bound P (Ex-P), 8.5–13.1% for Al-bound from (Al-P), 7.4–9.5% for Fe-bound P (Fe-P), 5.0–12.4% for reductant-soluble P (Oc-P), 9.7–15.6% for CaCO 3 -bound P (ACa-P) and 45.9–54.6% for detritus P (Det-P). The P distribution and concentration was consistent with other Chinese coastal seas. No significant difference was found for the sedimentary P forms between scallop cultivation area and background area, indicating that shellfish aquaculture did not have significant effect on the depositional environment in the studied area, at least in case of P. [ABSTRACT FROM AUTHOR]

Abstract: One of the fundamental purposes of quantitative acoustic surveys of seafloor hydrothermal vents is to measure their 2-D temperature distributions. Knowing the system latencies and the acoustic center-to-center distances between the underwater transducers in an acoustic tomography system is fundamental to the overall accuracy of the temperature reconstruction. However, commercial transducer sources typically do not supply the needed data. Here we present a novel calibration algorithm to automatically determine the system latencies and the acoustic center-to-center distances. The possible system latency error and the resulting temperature error are derived and analyzed. We have also developed the experimental setup for calibration. To validate the effectiveness of the proposed calibration method, an experimental study was performed on acoustic imaging of underwater temperature fields in Lake Qiezishan, located at Longling County, Yunnan Province, China. Using the calibrated data, the reconstructed temperature distributions closely resemble the actual distributions measured with thermocouples, thus confirming the effectiveness of our algorithm. [Copyright &y& Elsevier]

Abstract: Bohai Bay, the second largest bay of Bohai Sea, largely due to the huge amount of pollutants discharged into it annually and its geohydrologic condition, is considered to be one of the most polluted marine areas in China. To slow down, halt and finally reverse the environmental deterioration of Bohai Sea, some researchers have proposed to connect it with Jiaozhou Bay in the western coast of Southern Yellow Sea by digging an interbasin canal through Shandong Peninsula. In order to assess the heavy metal pollution and provide background information for such a large geoengineering scheme, surface sediments from 42 stations covering both riverine and marine regions of the northwestern coast of Bohai Bay were analyzed for heavy metal content and fractionation (Cd, Cr, Cu, Ni, Pb and Zn). Three empirically derived sediment quality guidelines were used to assess the pollution extent of these metals. The studied metals had low mobility except for Cd at all stations and Zn at some riverine stations. Although a high mobility of Cd was observed, it could hardly cause a bad effect on the environment owing to its low total concentrations. Anthropogenic influence on the accumulation of studied heavy metals in sediments of Bohai Bay was obvious, but their contents were relatively lower to date comparing with some other marine coastal areas that receive important anthropogenic inputs. Taking as a whole, surface sediments of northwestern Bohai Bay had a 21% probability of toxicity based on the mean effects range-median quotient. [Copyright &y& Elsevier]

Abstract: The chemical partitioning of 12 trace metals (Ba, Cd, Co, Cu, Mn, Mo, Ni, Pb, Sc, Sr, U, Zn) in 9 surface sediments from Daya Bay, northern South China Sea, was studied by a four-step sequential extraction technique to assess their environmental/pollution status. The studied metals take on different fraction composition patterns, and some of them show significant spatial variation especially for Cd. A majority of the studied metals can be considered immobile because of their high percentages in the residual fraction. It seems that the Daya Bay surface sediments have not yet been polluted by the studied heavy metals which are used as parameters to classify marine sediment quality, i.e., Cd, Cu, Ni, Pb and Zn. For all metals except for Pb, the extent of anthropogenic influences on their total concentrations in the Daya Bay surface sediments is generally imperceptible. The metals’ potential risks to the environment were assessed, and the results showed that they have generally no risk or low risk except for Cd, Mn and Sr. [Copyright &y& Elsevier]

Abstract: Associated with strong mixing and stirring, as well as enhanced bioproductivity and ecotones, oceanic fronts have garnered worldwide attention in recent years. Research into oceanic fronts, especially thermal fronts, has gained momentum since the advent of satellites and their increased accessibility. Yet, studies of salinity and nutrient fronts —particularly those that are subsurface are few and far between. This study reviews the most widely accepted facts about surface and subsurface temperature and salinity fronts in the Bohai, Yellow and East China seas and their seasonal variations. The distribution of nutrients in the surface and bottom waters are mapped and nutrient fronts, for the first time, are identified systematically. These fronts are generally strongest in winter when southward flowing coastal currents are influenced most by winter monsoons, and the contrasts between these cold, fresh, nutrient-rich currents and the northward flowing warm, saline but nutrient-poor Kuroshio are strongest. Surface fronts are generally weakest in summer when coastal currents may be weaker and temperature, salinity and nutrient contrasts are diminished. The existence of fronts and why some are disconnected are mainly related to oceanic features such as topography, boundaries between water masses and current flow patterns. Three latitudinal temperature and nutrient fronts in the southern East China Sea in winter may suggest eastward flowing currents. These currents have not been described previously. [Copyright &y& Elsevier]

Abstract: Due to anthropogenic activities, the nutrient loadings of the Changjiang (Yangtze River) are strickly on the rise. The high nutrient concentrations notwithstanding, river water was pCO2 supersaturated in the inner estuary during summer 2003 but decreased quickly in the mid-estuary due to mixing with low pCO2 waters from offshore. In addition, settling of particles in the estuary resulted in better light conditions so that phytoplankton bloomed, driving down pCO2 to ∼200μatm. In the outer estuary and outside of the bloom area, pCO2 increased again to near or just below saturation. Literature data also reveal that the mainstream of the Changjiang is always supersaturated with respect to CO2 probably because the decomposition of terrestrial organic matter overwhelms the consumption of CO2 due to biological production. Because the Changjiang outflow accounts for 90% of the total river flow to the East China Sea (ECS), any variation in the Changjiang could have significant implications for the ECS. For instance, completion of the Three Gorge''s Dam could change the metabolic status of the estuary by cutting off 70% of the downstream transport of organic carbon-containing particles. This would reduce the extent of organic carbon decomposition, producing better light conditions and enhancing autotrophy. As a result, the estuary could become a smaller source of CO2 to the atmosphere. On the other hand, if the Three Gorge''s Dam reduced freshwater output, especially in summer, upwelling of nutrient-rich offshore waters would be reduced resulting in a reduction in autotrophy in the much wider ECS shelves. This effect could outweigh the reduced heterotrophy in the estuary and the ECS as a whole could become a smaller CO2 sink. [Copyright &y& Elsevier]

The paleoclimate since 14 kyr BP (14C age) was reconstructed based on a 16.22-m-long sediment core collected from Lake Yanhaizi, a saline lake located near the northern limit of the East Asian summer monsoon in Inner Mongolia. Coarse sediments were deposited there during a shrinkage phase of the lake when sand dunes reactivated. These sediments have low organic carbon contents but high maturity indices, indicating that they were deposited in an arid environment. By contrast, based on high organic contents and low maturity indices, fine sediments were deposited during periods of high lake stand in a humid environment. It was in general dry between 8.0 and 4.3 kyr BP. The above dry and wet phases are consistent with those recovered from the arid–semiarid transition zone elsewhere, but are unlike the widely perceived humid Holocene Megathermal reported in east China and the newly reconstructed record in the alpine Retreat Lake in Taiwan. The discrepancy may be due to a relative insensitivity to humidity changes in these two areas since they have both been under the total influence of the summer monsoon. On the other hand, much enhanced evaporation over higher monsoon precipitation at Lake Yanhaizi reduces the effective humidity in the warm climate near the northern boundary of the summer monsoon. This also accounts for the fact the high-temperature Holocene Megathermal, as revealed in the Okinawa Trough and the northern South China Sea, is correlated to the dry phases at Lake Yanhaizi. Conversely, the 4–2-kyr BP coldest period in the Holocene corresponds to a wet phase at Lake Yanhaizi. [Copyright &y& Elsevier]

Conventional wisdom is that, in winter, the China Coastal Current flows southward on the western part of the Taiwan Strait, but on the eastern part of the Strait, a branch of the Kuroshio flows northward. The net flux is subject to debate, but it is believed to be small. This author opted to choose a northward flux of 0.2 Sv. Others believe that there is zero net flux, or the net flow may even be towards the south. Thus, it is very surprising to find a net northward flux as much as 2.74 Sv in early March 1997 (reported).Historical data are presented here to show that the salinity, temperature and nutrient concentrations are relatively homogeneous in the Taiwan Strait, in summer. The high salinity and temperature, but low nutrients, suggest that the water originates from the South China Sea (SCS) or the Kuroshio. In winter, on the other hand, steady and strong NE winds push the fresh, cold, nutrient-rich China coastal water southward, along the western part of the Taiwan Strait. Some salty and warm, but still nutrient-poor, SCS or Kuroshio water flows northward on the eastern part of the Strait.The present author concludes that the observed northward flux in early 1997 was caused by a sudden relaxation of the steady NE wind. As a result, any seawater that would have moved northward, but had been halted for several months by the NE wind, moved suddenly northward. Indeed, rarely occurring southerly wind in winter was observed briefly during the research cruise. Other physicochemical parameters of the waters suggest also that the observed northward-flowing water had originated mainly from the southward-flowing China Coastal Current, rather than the SCS or the Kuroshio. The physicochemical data support also the concept that the western part of Taiwan Strait was occupied by the China Coastal Current, which normally flows southward in winter. [Copyright &y& Elsevier]

Abstract: Slag material was dumped in two sites off southwestern Taiwan by the China Steel Corporation during 1984–1995. By geochemically analyzing four sediment cores, we investigated the impact of slag on the sediment chemistry. Elemental profiles from the dumping sites show a strong depletion in detrital elements and enrichment in alkaline and redox-sensitive elements, especially for the top ∼20cm of sediments. The relative enrichment factor (EFrel) exhibits wider range for Ca (0.73–13.33), Fe (0.88–3.03), Mg (0.94–9.58) and Mn (1.22–33.30) due to contamination of sediments by slag. Sediment weathering indicators also show a distinct change with lower values in sediments influenced by dumping due to Ca and Sr addition. Higher EFrel for As, Cd and Pb in the top sections of the cores indicate an additional modern/industrial input of these elements since ∼1950. Our study suggests that slag dumping may have a localized effect on biogeochemical processes by inducing the diagenetic remobilization of certain elements. [Copyright &y& Elsevier]

In this study, a method was developed for the desalination and pre-concentration of three colloidal trace metals in seawater, namely Cd, Cu and Pb, using diethylammonium diethyldithiocarbamate and ammonium 1-pyrrolidine dithiocarbamate as chelates. Seawater samples were first treated with cross-flow ultrafiltration (CFUF) for the separation of the colloidal matter of different molecular weights, i.e. 1–3 kDa, 3–10 kDa and 10 kDa-0.22 μm. Then, after acid digestion, the organic chelates and the extracting agent chloroform were added at pH = 3.8. Finally, the organic phase was back extracted, and the target metals in all samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) with low detection limits in the range of 0.13–1.18 pmol L−1. The extraction efficiencies for the three metals were in the range of 92.2%–100.3% with an enrichment factor of 40, and their mass recoveries in the studied colloidal fractions were in the range of 83.1%–103.5%. The developed method has been successfully applied for the analysis of seawater samples collected from the sites off the south coast of North Yellow Sea in Shandong Peninsula, China. For the first time, the distribution of colloidal Cd, Cu and Pb in different molecular weights in this area is reported. The results obtained from real samples demonstrate that the developed method is simple, efficient and convenient for routine analysis with low detection limit. Unlabelled Image • A pre-concentration method for colloidal metals in seawater was developed. • This method combined cross-flow ultrafiltration with liquid-liquid extraction for the first time. • The enrichment factor of the method could reach up to 40. • Real seawater samples were successfully tested and excellent results were obtained. [ABSTRACT FROM AUTHOR]

Abstract: This study for the first time examined dissolved metals (Cu, Cd, and Mn) together with dissolved oxygen and carbonate system in the whole Pearl River Estuary system, from the upper rivers to the groundwater discharges until the estuarine zone, and explored their potential impacts in the adjacent northern South China Sea (SCS) during May–August 2009. This river-groundwater-estuary system was generally characterized by low dissolved metal levels as a whole, whilst subject to severe perturbations locally. In particular, higher dissolved Cu and Cd occurred in the North River (as high as 60nmol/L of Cu and 0.99nmol/L of Cd), as a result of an anthropogenic source from mining activities there. Dissolved Cu levels were elevated in the upper estuary near the city of Guangzhou (Cu: ∼40nmol/L), which could be attributable to sewage and industrial effluent discharges there. Elevated dissolved metal levels (Cu: ∼20–40nmol/L; Cd: ∼0.2–0.8nmol/L) also occurred in the groundwaters and parts of the middle and lower estuaries, which could be attributable to a series of geochemical reactions, e.g., chloride-induced desorption from the suspended sediments, oxidation of metal sulfides, and the partial dissolution of minerals. The high river discharge during our sampling period (May–August 2009) significantly diluted anthropogenic signals in the estuarine mixing zone. Of particular note was the high river discharge (which may reach 18.5 times as high as in the dry season) that transported anthropogenic signals (as indicated by dissolved Cu and Cd) into the adjacent shelf waters of the northern SCS, and might have led to the usually high phytoplankton productivity there (chlorophyll-a value >10μg/L). [Copyright &y& Elsevier]

Abstract: Results of clay mineralogy in 140 samples collected in major rivers and lakes in southwestern Taiwan and on the seafloor off Taiwan in the northeastern South China Sea (SCS), combined with clay mineral records of the Pearl River drainage basin, rivers in Luzon, and the South China shelf and slope, are used to semi-quantitatively evaluate the detrital fine-grained sediment contribution of Taiwan to the northern SCS. The clay mineral assemblage of the Taiwan-sourced sediments consists dominantly of illite (average 56%) and chlorite (41%), with very scarce kaolinite and smectite. Their respective distribution from the rivers and lakes to the seafloor off Taiwan does not show obvious basin-wide differences. Linear correlations of illite chemistry index with illite crystallinity and of illite crystallinity with kaolinite (%) present two end-members of provenances, the Pearl River and Taiwan, for the South China shelf and slope. Assuming that kaolinite in the northern SCS is provided completely from the Pearl River, the contribution of Taiwan in clay minerals is evaluated as 29% to the South China shelf and 23% to the South China slope, respectively. Accordingly, the contribution of the Pearl River to the South China shelf and slope is 52% and 31%, respectively. The Luzon Arc accounts for the rest of clay mineral components for the northern SCS mainly by providing smectite. The Bashi Strait-crossed branches of the southward deep North Pacific Deep Water and the northward surface Kuroshio Current in the western Pacific may transport Taiwan-sourced suspended sediments westwards to the northern SCS. [Copyright &y& Elsevier]

In this study, we examined possible impacts of the Yangtze River Three Gorges Dam (TGD), the world largest hydroelectric construction, on the adjacent marine ecosystem of the East China Sea (ECS) during its initial water storage period. The TGD filled the first one-third of its storage capacity of 39 billionm3 in 10 days in June 2003, causing an abrupt reduction in the river flow into the ECS. Noticeable changes in the microbial community structure including pico-sized autotrophs, heterotrophic bacteria and microbial diversity in the estuary and the ECS were observed 2 months later. Although causes for these changes could be multiple, the sudden decrease of river runoff and an ensuing intrusion of ECS ocean currents were postulated to be among the major ones. [Copyright &y& Elsevier]

Seven cruises were carried out in a bay scallop (Argopecten irradians) farming area and its surrounding waters, North Yellow Sea, from March to November 2017 to study the dynamics of the carbonate system and its controlling factors. Results indicated that the studied parameters were highly variability over a range of spatiotemporal scales, comprehensively forced by various physical and biological processes. Mixing effect and scallop calcification played the most important role in the seasonal variation of total alkalinity (TAlk). For dissolved inorganic carbon (DIC), in addition to mixing, air-sea exchange and microbial activity, e.g. photosynthesis and microbial respiration processes, had more important effects on its dynamics. Different from the former, the changes of water pH T , partial pressure of CO 2 (pCO 2 ) and aragonite saturation state (Ω A ) were mainly controlled by the combining of the temperature, air-sea exchange, microbial activity and scallop metabolic activities. In addition, the results indicated that massive scallop farming can significantly increase the DIC/TAlk ratio by reducing the TAlk concentration in seawater, thereby reducing the buffering capacity of the carbonate system in seawater especially for Ω A . Preliminary calculated, ~75.7 and ~45.5 μmol kg -1 of TAlk were removed from the surface and bottom waters respectively in one scallop cultivating cycle. If these carbonates cannot be replenished in time, it is likely to accelerate the acidification process of coastal waters. This study highlighted the control mechanism of the carbonate system under the influence of bay scallop farming, and provided useful information for revealing the potential link between human activities (shelled-mollusc mariculture) and coastal acidification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In situ field investigations coupled with laboratory incubations were employed to explore the surface sedimentary phosphorus (P) cycle in a mariculture area adjacent to the Yangma Island suffering from summer hypoxia in the North Yellow Sea. Five forms of P were fractionated, namely exchangeable P (Ex-P), iron-bound P (FeP), authigenic apatite (CaP), detrital P (De-P) and organic P (OP). Total P (TP) varied from 13.42 to 23.88 μmol g -1 with the main form of inorganic P (IP). The benthic phosphate (DIP) fluxes were calculated based on incubation experiments. The results show that the sediment was an important source of P in summer with ~39% of the bioavailable P (BioP) recycled back into the water column. However, the sediment acted a sink of P in autumn. The benthic DIP fluxes were mainly controlled by the remobilizing of FeP, Ex-P and OP under contrasting redox conditions. In August (hypoxia season), ~0.92 μmol g -1 of FeP and ~0.52 μmol g -1 of OP could be transformed to DIP and released into water, while ~0.36 μmol g -1 of DIP was adsorbed to clay minerals. In November (non-hypoxia season), however, ~0.54 μmol g -1 of OP was converted into DIP, while ~0.55 μmol g -1 and ~0.28 μmol g -1 of DIP was adsorbed to clay minerals and bind to iron oxides. Furthermore, scallop farming activities also affected the P mobilization through biological deposition and reduced hydrodynamic conditions. The burial fluxes of P varied from 11.67 to 20.78 μmol cm -2  yr -1 and its burial efficiency was 84.7-100%, which was consistent with that in most of the marginal seas worldwide. This study reveals that hypoxia and scallop farming activities can significantly promote sedimentary P mobility, thereby causing high benthic DIP flux in coastal waters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

When fine particulates such as those with a diameter of approximately 1 μm (particulate matter, PM 1 ) are released from fossil fuel combustion into the air, they warm the atmosphere and contribute to millions of premature deaths in humans each year. Considerable quantities of PM 1 eventually enter the oceans as suspended particulates, yet subsequent removal mechanisms are poorly understood. In fact, the presence of PM 1 in marine biota has never been reported. Since sea anemones are opportunistic suspension feeders, they are anticipated to incorporate and accumulate PM 1 in their bodies. By histological examination, PM 1 was detected in 21 of the 22 sea anemones collected from Taiwan and Southeast China, with a depth of intertidal zone to 1000 m. PM 1 , if present, was always detected in endodermal layers and had the same dominant color (i.e., black, brown, or green) in different species from the same site. The bioaccumulation factor of PM 1 in sea anemones was approximately 5-7 orders of magnitude. Based on radioisotope 14 C results, the contribution of fossil fuel source PM 1 was 8-24%. Regardless of PM 1 's color, S and Fe were commonly detected by scanning electron microscopy and energy-dispersive spectrometry (SEM-EDS), suggesting anthropogenic sources. Furthermore, a maternal transfer of materials was suggested based on the existence of PM 1 in sea anemone eggs and in brooding and released juveniles. The significance of PM 1 accumulation by biota in aquatic ecosystems and the potential risk to living organisms via food webs warrant further investigation.

Compared to rivers in Europe and North America, Chinese rivers that discharge into oceans have different organic carbon (OC) transport characteristics. Out of the top 25 largest rivers worldwide, three (Changjiang, Huanghe, and Zhujiang rivers) are located in China, along with numerous small rivers. Thus, synthesized estimates of total riverine OC flux from Chinese rivers into marginal seas are critical but remain deficient. In this study, we developed relationships between riverine OC (dissolved OC, or DOC, and particulate OC, or POC) and basin characteristic variables (basin population density, precipitation, and riverine suspended sediment concentration) to estimate annual riverine DOC and POC fluxes during 1953-2016. The results showed that rivers in mainland China transported 9.63 Tg C of OC to the marginal seas in 2008, with 4.61 Tg C of DOC and 5.02 Tg C of POC. Of this transported OC, 14.28% DOC and 17.49% POC were transported by small southeastern rivers, whose drainage areas covered only 6.68% of the total. Because of intensifying human activities, DOC export increased but POC export decreased during 1953-2016. Additionally, basin population growth and reservoir water capacity were the major factors for increasing DOC flux and decreasing POC flux, respectively. Overall, the DOC/POC ratio increased for OC transport in Chinese rivers. Therefore, this study is important for understanding human-induced impacts on environmental change and the carbon cycle in marginal seas., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Historically, the Bohai Sea is one of the most important fishing grounds in China. Yet, surrounded by one of the biggest economic rims of China, its ecological functions have been declining rapidly in recent two decades under the heavy anthropogenic impacts. The Laizhou Bay is the smallest one of the three main bays in the Bohai Sea. Owing to the rich brine deposits, chemical industries using brine as raw materials are booming in the southern coast of the Laizhou Bay, the scale of which ranks as the largest one in China. In order to monitor and assess the environmental quality, surface sediments were collected from the coastal waters of southwestern Laizhou Bay and the rivers it connects with during summer and autumn in 2012, and analyzed for heavy metals. Several widely adopted methods were used in the overall assessment of heavy metal pollution status and potential ecological risks in these sediments, and the data were analyzed to infer the main sources of the pollutants. The results showed that the remarkably high concentrations of heavy metals were almost all recorded in a small number of riverine sites. Cr, Cu, Ni and Zn were the main environmental threat according to the sediment quality guidelines. The marine area was generally in good condition with no or low risk from the studied metals and adverse effects on biota could hardly occur. Natural sources dominated the concentrations and distributions of Cu, Ni, Pb and Zn in the marine area. Our results indicated that heavy metal pollution was not a main cause of the ecological degradation of the Laizhou Bay at present.

The surface sediments from Laizhou Bay (LB) and the coastal sea around Zhangzi Island (ZI) were analyzed for acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) to assess the sediment quality. These two areas, especially LB, are important mariculture bases in China and are significantly affected by the Yellow River. The concentrations of AVS ([AVS]) and SEM ([SEM]) varied in the ranges 0.71-11.03 and 0.10-0.74 μmol g(-1) dry weight, respectively. [AVS] was generally low in the river outlet area and increased in the seaward direction in LB. [AVS] was significantly and positively correlated with TOC. [SEM] was significantly and positively correlated with TOC, the water content of sediment and the fine sediment fraction and it was significantly and negatively correlated with coarse sediment fraction. The obtained results suggest that the surface sediments of LB and ZI were of high quality and not likely to cause negative effects on their ecosystems., (Copyright © 2013 Elsevier Ltd. All rights reserved.)