Bian, C. W.; Jiang, W. S.; Pohlmann, T., and Sündermann, J., 2016. Hydrography-physical description of the Bohai Sea.

The Bohai Sea used to be one of the most important fishing grounds in China. Recently, its ecological functions have declined rapidly due to the heavy anthropogenic activities which make ecological environment protection and restoration particularly topical in this region. Understanding the oceanographic conditions of the Bohai Sea is essential to evaluate the living environment (e. g. temperature and salinity) of planktons and transport fluxes of nutrients, sediments and contaminations. In this paper, we will analyze the published literature and data sets containing field observations, remote sensing reconstructions and numerical model results, and describe the principle features of the hydrodynamic system in the Bohai Sea, such as external forces, thermohaline patterns, tides, waves, currents and substance transport processes. The objective of this paper is to provide a general picture of the hydrography of the Bohai Sea; by this means the work may be beneficial for studies in other disciplines, too.

Gao, Z. G.; Zhang, Q. H.; Wang, H.; Zou, T.; Liu, K. X., and Wu, S. Q., 2016. The impacts of wind and air pressure on fluctuations of the mean Bohai Sea level

A numerical ocean model is employed to simulate mean sea level along coast of the Bohai sea for quantitative analysis on the contribution of wind and pressure to coastal mean sea level variations. It's shown that numerical results represent well the temporal and spatial character of mean sea level along coast of the Bohai Sea, and can be used to analyze mean sea level abnormity events. It's found that seasonal mean sea level variation caused by wind and air pressure accounts for about 70% of the variation of mean sea level. The three abnormal events of mean sea level occurred in Nov., 1988, Oct., 2006, and Feb., 2010 respectively indicate that sea surface air pressure and wind variation caused a wind-driven current. Consequently, water transportation is of great importance for the seasonal variations of mean sea level.

Li, Y. F.; Zhang, H.; Tang, C.; Zou, T., and Jiang, D. J., 2016. Influence of rising sea level on tidal dynamics in the Bohai Sea.

Recent studies highlight that tidal propagation in shallow waters tends to be modified with mean sea level rise, intensifying coastal threats. This study aims to obtain a comprehensive insight into the changes in tidal regimes in the Bohai Sea of China in response to local mean sea level rise. To achieve this goal the hydrodynamic model ROMS, previously calibrated and validated for Bohai Sea, was applied, considering local sea level rise scenario of 0.5 m, 1 m, 2 m and 3 m in the future, respectively. The model results show that under sea level rise conditions the amplitude of the main semidiurnal (M₂) constituent decreases in most areas except two areas where are around two amphidromic points, and changes in amplitude are not proportional to the level of sea level rise. However, compared results implied that it is necessary to consider the spatial-distribution of sea level-rise when predicting the effects of sea level rise in the future. The tidal wave also was distorted in the coastal zone, the changed wavelength made the amphidromic points move to deep water. Tidal current magnitude decreases with mean sea level rise, which could influence transport of sediment nearby coast of Bohai and Laizhou Bay.

Xing, G. P.; Wang, H. J.; Yang, Z. S., and Bi, N. S., 2016. Spatial and temporal variation in erosion and accumulation of the subaqueous Yellow River Delta (1976–2004).

Yellow River Delta (YRD), one of the most heavily human-influenced delta systems, had undergone dramatic changes since 1976. To determine the erosion and accretion pattern of the subaqueous YRD, bathometry data as well as the sediment discharge from the Lijin station over the period of 1976 to 2004 were analyzed. The erosion and accretion pattern of the subaqueous YRD was delineated by 1) the northern abandoned delta lobe, consisted of the heavily eroded Diaokou (DK) and Shenxiangou (SXG) lobes; 2) the active delta lobe, comprised of Qingshuigou (QSG) and Q8 lobes and featuring fast progradation; 3) the Laizhou Bay (LZB) with slight accumulation. Three stages were summarized based on the evolution of the northern abandoned delta lobe. During 1976–1980, the northern abandoned delta was severely eroded due to the cutoff of sediment supply. As the subaqueous slope became gentler during 1980–1996, the deeper part of the subaqueous delta turned into slight accretion state while the shallow part continued to be eroded. However, the erosion rate of the northern delta slowed down to a relatively balanced state during 1996–2004. Meanwhile, the development of the active delta lobe was a product of riverine sediment supply, channel geometry and estuarine hydrodynamics. Multi-depocenter was formed along the coastal area of the active subaqueous delta during 1976–1980, when multiple channels were active for sediment transportation. As the main river channel developed, the depocenter progradated eastward with an exceptional high accumulation rate during 1980–1985. The progradation direction turned southeastward with a lower accumulation rate during 1985–1996. Then, the depocenter shifted to the newly formed Q8 river mouth after a channel diversion in 1996, leaving the QSG river mouth in severe erosion. The channel diversion also caused erosion at the offshore area in LZB, where slight accumulation dominated before 1996. The erosion and accumulation pattern of the subaqueous YRD showed significant spatial and temporal variability during 1976–2004. A comprehensive understanding of their driven mechanisms would be critical for the prediction of the evolution of the YRD in the context of global change.

Zhang, X. D.; Zhang, Y. X.; Ji, Y.; Zhang, Y. W., and Yang, Z. S., 2016. Shoreline change of the northern Yellow River (Huanghe) Delta after the latest deltaic course shift in 1976 and its influence factors.

222 high-quality Landsat satellite images were used in this study to extract the instantaneous shoreline positions on 22 sections of the northern Yellow River delta. Based on the instantaneous water line position data, a new statistical method for studying annual shoreline change was proposed. The annual shoreline movement of the northern Yellow River delta after the latest deltaic course shift in 1976 was obtained. The results showed that the shoreline on northern Yellow River delta was mostly undergoing a retreat back process since 1976 due to the river course shift, relative sea level change, regional marine hydrodynamic forces and the local engineering constructions. The influence of the Yellow River deltaic course shift in 1976 on the shoreline change mainly occurred in the first 20 years in 1976–1996 after the course shift, and was mostly limited within 10 km range around the abandoned Diaokou river mouth. The coastal engineering constructions caused decrease of the erosion area by 61 km², or 31% of the total erosion area. Most of the northern Yellow River delta was relatively insensitive to the relative sea level change except for the coast around sections S10 and S11; The annual shoreline movement due to the relative sea level change along most of the coast was only 1–3% of the actual annual shoreline movement; the total erosion area due to the relative sea level change was 9 km², or 5% of the actual erosion area. The coast erosion in the northern Yellow River delta was mainly influenced by the regional marine hydrodynamic forces, which gradually increase from west to east, resulting in gradually eastward increase of annual shoreline movement and slope steepness of the coast.

Deng, J. J.; Harff, J.; Li, Y. F., Zhao, Y., and Zhang, H., 2016. Morphodynamics at the coastal zone in the Laizhou Bay, Bohai Sea.

Morphogenetic processes of the Yellow River Delta and the Laizhou Bay, Bohai Sea, China, have to be described by the interrelation of riverine sediment supply, relative sea level change and the effects of wind driven waves and nearshore currents. The research area is regarded a natural laboratory of the development of river dominated coastal zone with interfering natural and anthropogenic forcing factors. As well for the historical hindcast as for future projections of the morphogenetic coastal processes the Dynamic Equilibrium Shore Model (DESM) can be applied. This model generalizes the standard Bruun rule model and generates Digital Elevation Models (DEMs) scenarios on decadal to centennial time scales for the geological past and future. The basic concept is a dynamic equilibrium coastal profile evolution in adaption to the sediment budget in a spatially three-dimensional domain. By adding parameters to account for sediment mass contribution from riverine sediment flux, the DESM can be used to explore coastal morphological equilibrium states responding to sediment budget changes for river-dominated coastal zones. For the parameterization historical maps of the southern Bohai Sea have been applied to reconstruct paleo-coastlines for the 19^th century for the comparison with a modern DEM. Gauge measurements provided the data for an estimation of trends in sea level change for the Laizhou Bay on the decadal scale. Modern sea level rise together with reduced riverine sediment supply caused by anthropogenic activities such as damming up-streams may change the depositional environment at the Yellow River Delta and related areas of the Laizhou Bay from river dominated (progrational) to wave dominated (regressive) environment.

Dalledonne, G. L., and Mayerle, R., 2016. Modelling of storm impacts on the Shandong peninsula coast.

This paper presents results of the investigation of the effect of storms on the morphodynamics of the Yantai coastal areas in the Shandong Peninsula, China. A two-dimensional depth integrated morphodynamic model for prediction of the morphological changes during extreme events was developed and applied. The model covers the entire Bohai Sea with increasing grid resolution towards the coastal areas near Yantai. Calibration and validation using tidal constituents and measured water levels and current velocities showed that the model is capable of predicting the hydrodynamics in good agreement with observations. Emphasis was given to the proper description of the spatial distribution of the seabed sediments and bed stratigraphy. The 20 most severe storms observed in the region from 2000 to 2013 were identified and reconstructed. Storm surges with increases in mean sea level of up to 1.7 m and significant wave heights up to 4.1 m were considered. The results showed that during the storms the levels of energy are mainly due to waves and tidal currents are only relevant at the capes and some channels and straits along the Shandong Peninsula. The resulting morphological changes indicated that although there is an overall loss of seabed material, particularly during the peak of the storms, the beaches near Yantai recover quite quickly just a few days after the extreme events.

Wang, Q.; Zhong, S. Y.; Li, X. Y.; Zhan, C.; Wang X., and Liu, P., 2016. Supratidal land use change and its morphodynamic effects along the eastern coast of Laizhou Bay during the recent 50 years.

Using nautical charts, topographic maps, high resolution remote sensing images and field observation, this study analyzed the land use change of the supratidal zone and its coastal morphodynamic effects along the eastern coast of Laizhou Bay. The results show that land use along the eastern coast of Laizhou bay has been significantly changed in the recent 50 years. The main evolution trend is the transition from aeolian sandy land, woodland and farmland to aquaculture ponds and residential land since the early 1990s. A belt zone of aquaculture facility parallel to the coastline has been formed and dykes are constructed along the outside of the coastal aquiculture zone. The significant land cover change in the supratidal zone has profoundly modified the boundary conditions of storm surges. The hydrodynamic modeling results show that the ocean dynamics near the coastline are enhanced and caused severe erosion of the coastline, beach and underwater coastal sea slope along the eastern coast of Laizhou Bay over the recent 30 years.

Zou, T.; Zhang, H.; Meng, Q. J., and Li, J., 2016. Seasonal hydrodynamics and salt exchange of a shallow estuary in Northern China.

Estuaries are important components of coastal ecosystem and function as dominant pathways of material exchange at the land-sea interface. The transport of terrestrial input through river inflow is controlled by physical process including tides, waves, and fresh water discharge. This study investigates hydrodynamic characteristic and salt flux within Xiaoqinghe River (XQR) estuary, which is a shallow estuarine system (water depth < 8 m) and exports substantial amount of nutrients and pollutants to the adjacent Laizhou Bay. Profile velocity and salinity are measured using ADCP and CTD through complete tidal cycles (25 hours) in April, July and September 2013. The instantaneous velocity and salinity data are decomposed into time-averaged means and time-varying components based on the improved Kjerfve (1986) method to quantify the contributions of various physical processes. The results showed that the XQR estuary had irregular semidiurnal tide with tidal form number of 0.5–0.7 and tidal range about 2 m. River discharge dominated the seasonal variation of tidal elevation, longitudinal velocity, and salinity. The river mouth was well mixed based on calculated layer Richardson number, and can be classified as Type 1b and 2b according to stratification-circulation diagram. The net salt flux was directed seaward during monsoon season and landward in non-monsoon seasons. Fluvial advective flow dominated the seaward salt flux throughout the year and contributed 78.9% of the net salt flux in monsoon. Stokes' drift and tidal sloshing dispersion flux dominated the landward salt flux, and contributed 72% and 57.5% of total salt flux in April and September, respectively. The cross-correlation between tide and salinity, and vertical shear, were only of marginal importance. Overall, tidal sloshing and Stokes' drift is the underlying process of salt transport while river discharge dominates its seasonal variation. This study revealed the inherent unsteadiness of the salt balance, and provided the scientific foundation for effective management of freshwater release from upstream during difference seasons.

Wang, A. M.; Wang, H. J.; Bi, N. S., and Wu, X., 2016. Sediment transport and dispersal pattern from the Bohai Sea to the Yellow Sea.

Suspended sediment flux, dispersal patterns and its possible mechanisms in the Bohai Sea were investigated based on the observational data in May and November, 2012, data retrieved from MODIS imageries and the ocean current data from HYCOM. The sediment dispersal pattern and the annual net sediment flux presented evident seasonal variability. During wintertime, the prevailing strong northerly winds and the related high wave heights resuspended the sediment along the coast of the Huanghe Delta that was transported into the Laizhou Bay along its western coast and exported to the Bohai Strait through the eastern Laizhou Bay as enhanced by the coastal current. The wintertime contributed approximately 4.84 Mt of suspended sediment flux to the Yellow Sea, as higher than the flux in summertime by one order. In summertime, the less energetic environment together with the stratified water column was unfavorable to the sediment export to the Yellow Sea. As a result, the sediment delivered by the Huanghe to the sea in summertime mostly accumulated within the subaqueous delta, which acted as a primary source of sediment export to the Yellow Sea in wintertime.

Jiang, D. J.; Zhang, H.; Zou, T.; Li, Y. F.; Tang C., and Li, R. Z., 2016. Suspended particle size retrieval based on Geostationary Ocean Color Imager (GOCI) in the Bohai Sea.

The suspended particle size has an important effect on the settling velocity of particles, the penetration of sunlight into the sea and the transmission of sound. It is of importance to investigate the spatio-temporal distribution of suspended particle size. In this paper, a new empirical model was developed based on Geostationary Ocean Color Imager (GOCI) data for retrieving the median suspended particle size (d50), and then, the spatio-temporal variation in GOCI-retrieved d50 was analyzed over the Bohai Sea. The results showed that the new model gained the satisfactory retrieval results in the Bohai Sea. Spatially, median particle size in the Bohai Sea showed an obvious onshore-offshore gradient, which was smaller in the coastal waters, especially in the Laizhou Bay, the Bohai Bay, and the Liaodong Bay while larger at the Bohai strait and the northwest part of central Bohai Sea. Hourly variations of d50 data depicted the short-term dynamics of suspended sediments. The daily-averaged d50 had a similar pattern of spatial distribution and numerical values to the hourly data but with a distinct temporal variation. In addition, the findings of this study suggested the possible effects of tide, wind, turbulence and riverine input on the median particle size distribution.

Tang, C.; Li, Y. F.; Liu, X.; Zhao, Y., and Zhang, H., 2016. Risk of surface sediment erosion in the Bohai Sea, North Yellow Sea and its indication to tidal sand ridge occurrence.

Bottom geomorphological evolution and sediment distribution are under strong control of tidal forcing along China's coast. To quantify and assess the temporal-spatial change of bottom environment, a risk-based probabilistic concept of erosion is applied and maps of erosion risk are constructed. Sediment data categorized into 5 classes, together with hydrodynamic data in a temporal resolution of one hour and a model time of one month, are used to calculate the potential of erosion of surface sediments in the Bohai Sea, North Yellow Sea. Comparison with results of the tidal ellipse and bottom shear stress from model output shows that the highest risk of erosion is located in the Yalujiang Estuary, West Korea Bay, north of the Bohai Bay and in the surroundings of the Laotieshan channel of Bohai Strait, which may explain the occurrence of tidal sand ridges in the modeling domain.

Hou, L. J.; Li, H. L.; Zheng, C. M.; Ma, Q.; Wang, C. Y.; Wang, X. J., and Qu, W. J., 2016. Seawater-groundwater exchange in a silty tidal flat in the south coast of Laizhou Bay, China.

There were few studies about seawater-groundwater exchange in silty, low-permeability tidal flats with very gentle slopes. This paper reports the monitoring data and preliminary analytical results on a typical transect in a silty tidal flat with large-scale seepage faces at the south coast of Laizhou Bay, China. The “pair-wells method”, which was an improvement of the single-well method used by Ma et al. (2015) was used to estimate the seawater-groundwater exchange rate. We selected 14 locations along a typical transect in the intertidal zone, with a slope of 0.4‰ and cross-shore length of 3514 m, to install pair-wells for monitoring the groundwater head, salinity and temperature at two different depths simultaneously once per hour from 20:00 August 10th to 23:00 September 12th, 2014. The vertical hydraulic conductivity measured in situ ranges from 5.4 ×10⁻⁷ to 1.1×10⁻⁵ m s⁻¹. The salinity of the underground brine ranges from 25 to 56 g l⁻¹. Based on the observed data and the generalized Darcy's law, the submarine groundwater discharge (SGD) and inflow along the entire transect were estimated to be 164.0 and 6.5 m² d⁻¹, respectively. It is found that 80.4% of the total SGD occurred between W7 and W10, where the hydraulic conductivity is one or two orders of magnitude greater than that at other wells; and 64.6% of the total inflow occurred between W2 and W4. The single-well method, on the other hand, yields a SGD value of 223.0 m² d⁻¹ and inflow value of 13.3 m² d⁻¹. Neglecting the density effect may lead to an overestimation of the SGD by 25.6% and underestimation of the inflow by 27.4%.

Xing, Q. G.; Braga, F.; Tosi, L.; Lou, M. J.; Zaggia, L.; Teatini, P.; Gao, X. L.; Yu, L. J.; Wen, X. H., and Shi, P., 2016. Detection of low salinity groundwater seeping into the Eastern Laizhou Bay (China) with the aid of Landsat Thermal Data.

Low-salinity groundwater storages beneath the sea bottom and submarine groundwater discharges (SGD) are of great importance in environmental management and the use of coastal water resources. A preliminary hydro-morpho- geologic analysis allows for considering the presence of low-salinity groundwater in the offshore of the Laizhou Bay (Southern Bohai Sea, China). In order to detect the potential SGD, the analysis of the Sea Surface Temperature (SST) anomalies was carried out using Landsat thermal images acquired in the seasons characterised by the largest difference in temperature between seawater and groundwater. At the nearshore scale, patchy cold water anomalies occur approximately in the same positions along the intertidal zone of the Southern bay, where the unconfined aquifer discharges, independently of tide conditions. At the embayment scale, cold water anomalies spread out in the Eastern Laizhou Bay where the confined aquifer is likely exposed. Salinity and temperature measured in surficial waters of the eastern Laizhou Bay support the hypothesis of SGD, which can be derived from remote sensing images; the occurrence of macroalgal blooms might also be the consequence of the SGD-enhanced nutrient supply. This work pointed out the need of future oceanographic and groundwater flow modeling along with long-term monitoring of processes associated with the suspected SGD. The outcomes of this preliminary study will be of great help to direct effective in-situ investigations aimed at quantifying the volumes of SGD and to simulate coupled groundwater/surface-water flow.

Gao, M. S.; Hou, G. H., and Guo, F., 2016. Conceptual model of underground brine formation in the silty coast of Laizhou Bay, Bohai Sea, China.

There were three major transgression-regression events since the late Pleistocene in the southern coast of Laizhou Bay, Bohai Sea, China. The three marine facies were correspondingly formed. Large amount of underground brine has been found in the late Pleistocene aquifers. A multi-source fluvial delta sedimentary system where the processes of replenishment, migration, filtration, storage, capping condition act together may be more dominant for the formation of underground brine. The dissolved salinity in the liquid of surface microtopography such as lagoon, paleochannel and tidal creek was originated from marine sediment and influenced partly by normal seawater over the time interval, which ran across the bar during the process of storm surge sometimes, but the water body in the sediment only came from fresh groundwater in the fluvial delta. In order to better understand and utilize the underground brine resources, we proposed a conceptual model about the formation of underground brine. Underground brine evolution can be categorized into two stages with six processes. The first stage could be the early regression period. Taking microrelief as a control condition of brine generated reactor, dissolved components were fractionated under the effect of pump evaporation combined with ion exchange between sediment and pore water, leading to the mineral composition changes in groundwater. As a result, underground brine was generated in the tidal flat and delta front under the effect of backflow-infiltration. The saline brine flushed into the tidal flat and the delta front under the effect of backflow-infiltration and remained stable with high degree of mineralization for a long time. The second stage would be the end period of regression. Brine-producing reservoir was formed by a combined effect of both long-term evaporation and seasonal fluvial material input. When lateral terrestrial deposit covered the early brine layer, the underground brine was then formed. Therefore, the three underground brine layers were results of three large scale sea-land changes.

Witkowski, A.; Li, C. L.; Zg[lstrok]obicka, I.; Yu, S. X.; Ashworth, M.; Dąbek, P.; Qin, S.; Tang, C.; Krzywda, M.; Ruppel, M.; Theriot, E. C.; Jansen, R. K.; Car, A.; Płociński, T.; Wang, Y. C.; Sabir, J. S. M.; Daniszewska-Kowalczyk, G.; Kierzek, A., and Hajrah, N. H., 2016. Multigene assessment of biodiversity of diatom (Bacillariophyceae) assemblages from the littoral zone of the Bohai and Yellow Seas in Yantai region of Northeast China with some remarks on ubiquitous taxa.

Diatoms are important contributors to the benthic microeukaryote flora. This manuscript lays the foundation for future metagenomic and environmental sequencing projects off coastal China by curating diatom DNA sequences from the Yantai region of the Bohai and Yellow Seas (Northeast China). These studies are based on cultures established from samples collected in different seasons from marine littoral and supralittoral zones in 2013 and 2014. Thirty-six diatom strains were cultured successfully and identification of these clones was determined by light and scanning electron microscopy(LM and SEM) and DNA sequencing of the nuclear-encoded small subunit ribosomal RNA (SSU)and chloroplast-encoded rbcL and psbC genes. The strains primarily represent raphid pennate genera, such as Amphora, Amphora (Oxyamphora), Caloneis, Diploneis, Halamphora, Navicula, Nitzschia, Parlibellus, Pleurosigma, Surirella and Tryblionella. When the DNA markers from these strains were analysed in a multi-gene phylogeny, we found that some clones-particularly within the genera Amphora, Navicula and Nitzschia—show greater than expected genetic diversity despite their very similar morphology and morphometrics. We also compared the molecular and morphological identities of several seemingly ubiquitous marine littoral taxa in the genera Amphora and Nitzschia from the Indian Ocean and Atlantic Ocean, the Red Sea and Adriatic Sea to their Yellow Sea counterparts.

Li, J. L.; Lin, S. Y., and Song, Q., 2016. Characteristics of sediment bacterial community in response to environmental impacts in a sewage polluted river.

The Jiaolai River is the main source of industrial and irrigation water for its catchment of 3900 km². Anthropogenic activities have caused heavy pollution of this river, but their impacts on biota have never been evaluated. In this study, molecular techniques were applied to investigate the impacts of environmental pollution on the river. Quantitative PCR revealed that total bacterial abundance ranged from 2.90×10⁷ to 2.12×10⁸ copies/g, with no significant differences among sampling sites or seasons. Bacterial abundance and pore water ammonium concentration were negatively correlated. Cluster analysis revealed that bacterial communities were mainly distributed into groups corresponding to nitrate concentration. Two clone libraries were constructed to compare the bacterial composition of samples with high (J308) and moderate (J304) nitrate impact. Sample J308 was characterized by more members in Clostridia and disappearance of Betaproteobacteria members, which are the primary contributors to nitrogen biogeochemical cycling. Bacterial communities in the sediment were clearly differentiated by environmental nitrogen pollution, suggesting that nitrogen eutrophication was the main environmental problem influencing the Jiaolai River.

Liu, X.; Pan, G. C.; Wang, Y. B.; Yu, X.; Hu, X. K.; Zhang, H., and Tang, C., 2016. Public attitudes on funding oil pollution cleanup in the Chinese Bohai Sea.

The loss in value of coastal resources due to oil spills is difficult to determine as the degraded areas are typically neither bought nor sold and have no transaction history. We used a questionnaire by Liu et al. (2009) and Choice Experiments (CEs) methodology to place values on coastal resources including coastal water, beaches, and sea birds in the Chinese Bohai Sea. Survey results showed that during spill response actions, coastal water, and beaches were of equal concern to Chinese households while sea birds were of somewhat less concern. Respondents with higher education and fewer children and those with relatively greater household income were more likely to state they were willing to pay for oil spill cleanup costs. Age of respondent was negatively correlated to willingness to pay for cleanup. We also compared valuations of coastal resources with studies conducted in North America and Europe making it possible to test the consistency of coastal resource valuation across continents.

Huang, G. P.; Chen, Y. J.; Tian, C. G.; Tang, J. H.; Zhang, H.; Luo, Y. M.; Li, J., and Zhang, G., 2016. Spatial distributions and seasonal variations of dissolved black carbon in the Bohai Sea, China.

To investigate the temporal and spatial variations of dissolved black carbon (DBC) concentrations in the Bohai Sea, China, 495 seawater samples on 141 sites were collected in different water depths and seasons in six cruises from 2010 to 2014 for DBC quantification by the molecular marker method-benzene polycarboxylic acid method. The average concentration of DBC was 96.6 ± 32.9μg L⁻¹(n = 495)in the entire Bohai Sea,while it was 136.2 ± 33.7 μg L⁻¹(n = 28) in the Laizhou Bay, 131.2 ± 30.3 μg L⁻¹(n = 44) in the Bohai Bay, 86.3± 16.1μg L⁻¹(n = 66) in the Liaodong Bay, 89.6±19.8μg L⁻¹(n = 277) in the Central Bohai Basin and 57.8 ± 8.6 μg L⁻¹(n = 80) in the Bohai Strait respectively. DBC concentrations showed a distinct decreasing trend from coastal area to offshore area and from the internal Bohai Sea to the Bohai Strait in horizontal distribution although no significant differences(p> 0.1)was observed in the vertical water column. The average DBC concentrations of the Central Bohai Basin and the Bohai Strait in spring, summer, autumn and winter were comparable. However the DBC concentration patterns in different seasons varied significantly, such as the DBC concentrations were lower in the southern than northern of the Bohai Strait in spring, but it was inversed in autumn and winter. The seasonal variations of DBC concentration patterns followed the seasonal variations of ocean currents, suggesting that DBC would serve as a potential marker for the hydro-dynamics study.