The Laizhou Bay(LB)represents a substantial ecological area that is vulnerable to human activities and confronts diverse environmental challenges.This study provides a comprehensive characterization of nutrients,petro...The Laizhou Bay(LB)represents a substantial ecological area that is vulnerable to human activities and confronts diverse environmental challenges.This study provides a comprehensive characterization of nutrients,petroleum,heavy metals,and phytoplankton community structure across seven distinct areas in LB.The results indicate relatively high concentrations of NO_(2)-N,SiO_(4)-Si,and NO_(3)-N in the Southwest Laizhou Bay(SWLB)and Huanghe River Estuary(HRE).In contrast,the East Laizhou bay(ELB)and the North of Huanghe River Estuary(NHRE)exhibit the highest concentrations of heavy metals(As,Cr and Hg).The areas with high phytoplankton density and community diversity are mainly located in the SWLB.After adjusting for basic environmental factors,phytoplankton density and Margalef richness index D are significantly associated with nutrients(NO_(3)-N,NO_(2)-N,NH_(4)-N,SiO_(4)-Si),and heavy metal(Cr)concentrations.We highlight that,in addition to Xiaoqinghe River,nutrients brought by the Mihe River in the SWLB and heavy metal(Cr)pollution in the ELB resulting from industrial and mining activities along the coast significantly influence phytoplankton growth and community structure.Therefore,it is recommended that more monitoring and management efforts be focused on these regions in the future.展开更多
We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018...We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018,gobies and sediments were collected from 15 stations.We measured the activities of defense enzymes and the contents of malondialdehyde(MDA)and metallothionein(MT)in the goby liver as well as the levels of heavy metals in the sediments and goby muscle tissue.Most of the heavy metal concentrations in sediment at each station were below the Class I criteria set by Chinese Standards for Marine Sediment Quality,and the Håkanson ecological risk index suggested low risk for the heavy metals.We found that A.ommaturus could eff ectively accumulate mercury,cadmium,arsenic,and zinc and that the contents of MT and MDA and the activities of glutathione peroxidase and glutathione reductase were suitable biomarkers of heavy metal pollution in this species.The IBRv2 method integrated these four biomarkers and discriminated stations according to heavy metal pollution.Higher IBRv2 values suggested more adverse eff ects in gobies,corroborating more serious heavy metal contamination.The stations with high IBRv2 values and high contents of heavy metals were mainly distributed in the west and northeast parts of the bay.These results show that the IBRv2 approach is a feasible strategy for assessing heavy metal pollution through biological response and biological status and that it can be implemented for environmental monitoring in Laizhou Bay.展开更多
The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in...The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in the reconstruction of historical coastal disasters.We investigated an anomalous sand layer in the Xiliyu Village by the coast of Laizhou Bay,Shandong,from which an extreme event deposit was identified using a multi-proxy approach including grain size distribution,geochemistry,and magnetic susceptibility.This event was dated 2700–3100 a bp,and caused inundation of a large coastal area of Laizhou Bay.By comparing historical records with instrumental data,we believe that the event deposit was generated by a severe storm surge with wind speed of>34.9 m/s.展开更多
Naturally occurring radium(^(223)Ra,^(224)Ra,^(226)Ra,and^(228)Ra)isotopes have been widely applied as geochemical tracers in marine environments,especially when estimating the submarine groundwater discharge(SGD).In ...Naturally occurring radium(^(223)Ra,^(224)Ra,^(226)Ra,and^(228)Ra)isotopes have been widely applied as geochemical tracers in marine environments,especially when estimating the submarine groundwater discharge(SGD).In this sense,the influencing factors and transport mechanism of radium isotope activity in aquifers can be key information for SGD estimation.This work evaluates the adsorption/desorption behavior of^(224)Ra and^(226)Ra in the solid-liquid phase through a leaching experiment and analysis of field data.The results suggested that radium isotope activity was positively correlated with salinity and grain size,in the case of abundant sediments.Through ion analysis,we found that the ions(Na^(+),Ca^(2+),Mg^(2+),and Ba^(2+))exchanged with radium isotopes in the process of transport.A 1-D reactive transport model was established to simulate the transport process of radium isotope in aquifers.The model successfully simulated the variation of radium isotope desorption activity with salinity and was subsequently verified in the field.This study contributes to the understanding of the geochemical behavior of radium isotopes in aquifers and provides guidance for selecting a suitable groundwater endmember in SGD estimation.展开更多
The disaster of seawater intrusion seriously affects people's lives and restricts economic development,so the detection and treatment of seawater intrusion is a long-term task.On the basis of field investigation a...The disaster of seawater intrusion seriously affects people's lives and restricts economic development,so the detection and treatment of seawater intrusion is a long-term task.On the basis of field investigation and water quality analysis,according to the change characteristics of apparent resistivity of groundwater after Cl-reaches 250 mg/L,the theoretical basis for the application of high-density resistivity method was determined,and the characteristic values of apparent resistivity for seawater intrusion interfaces in different geological characteristic regions in Laizhou Bay area were determined by typical profile tests.Combined with water quality investigation and other means,profiles for the high-density resistivity method were arranged,and the interfaces between saline and fresh water were accurately divided.展开更多
Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exis...Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C(AMS14C) and optically stimulated luminescence(OSL) ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7(MIS7), the last interglacial period(MIS5) and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes.展开更多
Salinity in estuaries has an important influence on sediment deposition,delta formation,and fishery economy.The change of runoff in Yellow River(YR),which is the largest river along the Bohai Sea,has an important effe...Salinity in estuaries has an important influence on sediment deposition,delta formation,and fishery economy.The change of runoff in Yellow River(YR),which is the largest river along the Bohai Sea,has an important effect on the salinity of the sea,particularly in Laizhou Bay.In this study,measured runoff data in Lijin hydrological station from 1950 to 2018 are adopted to examine the change of YR runoff into the sea.The study concludes that the runoff of YR is distributed unevenly throughout the year and the amount of runoff mainly concentrates during the flood season.Results show a decreasing trend at a significant level ofα=0.95,with a range of−6.17×10^9 m^3 yr−1.Three groups of runoff are set by using the Finite-Volume Coastal Ocean Model numerical model to analyze the change of salinity in Laizhou Bay.These modeled effects were compared with water level observations made by Bayuquan,Tanggu,and Penglai gauge stations and salinity surveys conducted by Longkou gauge station.Model results and observations of salinity distributions and coastal water level showed good agreement.We can conclude that the distribution of salinity in Laizhou Bay is high in the east and low in the west.Furthermore,it responded quickly to the change of the runoff from YR.Under conditions of high river discharge,the low-salinity zone increased in horizontal direction and reached the bottom in vertical direction.展开更多
Study on morphological changes of a bay can help to identify the effects of anthropogenic activities on coastal environ-ment and guide the exploration of marine resources.In this paper,morphological data including coa...Study on morphological changes of a bay can help to identify the effects of anthropogenic activities on coastal environ-ment and guide the exploration of marine resources.In this paper,morphological data including coastline and water areas in five discrete years between 1968 and 2015 were selected and extracted from the remote sensing images and historical marine charts to study the morphological changes in Laizhou Bay(LZB),one of the bays in the southwest of the Bohai Sea.A systematic analysis on spatial variations of the coastline and the surface areas of different types of waters in LZB was conducted.The results showed that the surface area of LZB was decreased by 1253.2km^(2)in the last half century,which is 17.4%of the total in the 1970s.The areas of the natural wetland and the intertidal zone were decreased by 17.2%and 56.1%,respectively,and the average water depth varied from 9.05 m to 8.16m at low tide level from 1968 to 2015.The coastline and shape variations of the bay turned to be complex after the 1980s,and the shape index of LZB showed an increasing trend in more recent years.The centroid of the bay generally migrated to the northeast direction,i.e.,the direction of the center of the Bohai Sea,and the shrinking direction of the bay was consistent with the migration direction of the coastline.The reclamation area during 1968-2015 in LZB was 1201.7km^(2),and 94.1%was in the inter-tidal zone.The overall morphological change of the bay during the last half century was mainly controlled by the coastal reclamation activities,and the Yellow River runoff including the river course change and sediment load variation was also an important control-ling factor.展开更多
The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses o...The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP: 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.展开更多
As an important part of the Bohai economic rim,the Laizhou Bay has been stressed by serious eco-environmental problems in recent years.In this study,the Shannon-Wiener index(H′),AZTI’s marine biotic index(AMBI)and t...As an important part of the Bohai economic rim,the Laizhou Bay has been stressed by serious eco-environmental problems in recent years.In this study,the Shannon-Wiener index(H′),AZTI’s marine biotic index(AMBI)and the multivariate AMBI(M-AMBI)were used to assess the ecological quality status(EQS)of the Laizhou Bay according to macrobenthos data collected annually in August 2011–2014.The results showed that the overall benthic habitat quality in the Laizhou Bay was assessed as“Good”.However,25%of the samples were classified as“Moderate”,“Bad”or“Poor”status under degraded conditions.Ecological group III(EGIII)species which had a certain tolerance to environmental disturbances had a higher proportion in each station,and most of them had appeared the pollution indicator species Capitella capitata.This indicated that the benthic habitat in the Laizhou Bay had been disturbed and polluted to some extent.The comparison of the three indices evaluation result and the RDA analysis showed that the H′and M-AMBI were more suitable when the relative abundance of the single species was high and the macrobenthic community was significantly imbalanced;when the relative abundance of opportunistic species(EGIV and EGV)was high,the AMBI and M-AMBI could reflected the EQS objectively;in an undisturbed and polluted environment,all the three indices could indicate the benthic habitats quality.In summary,the better correlation between the three indices and environmental factors showed that they were well responsive to the tendency of the benthic habitats quality in the Laizhou Bay.展开更多
This study is about the reconstruction of fluvial origins based on the grain size distribution of sediment deposits in the western Laizhou Bay,Bohai Sea,China.Thirteen sediment cores were selected to research sediment...This study is about the reconstruction of fluvial origins based on the grain size distribution of sediment deposits in the western Laizhou Bay,Bohai Sea,China.Thirteen sediment cores were selected to research sediment characteristics using the Sahu discriminant formula,C-M diagram,and Folk method.The results showed:(1)Bounded by the Guangli River estuary,the north sediment was affected by the water and sand flowing from the Yellow River during different periods.The south sediment came from multi-source rivers under the influence of the Xiaoqing River,Mihe River,and other coastal rivers;(2)the deposited sediments were dated by a clear historical record of the branched channel oscillation combined with the characteristics of the diversion channel,erosion,and regression.The subaqueous delta overlapped during several Yellow River channel runs(1897–1904,1929–1934,1938–1947,1947–1953,1976–1996)and the deposited sediment facies changed(the north tidal flat-abandoned subaqueous delta-lateral delta-delta front);(3)the deposited sediment characteristics can be revealed by studying the branched diversions of the Yellow River and coastal multi-rivers of the past one hundred years.展开更多
Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, ...Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, five factors were selected in the fuzzy-synthetical evaluation approach to form the index system, so as to evaluate the degree of sea/saltwater intrusion in southern Laizhou Bay. The results show that the sea/saltwater intrusion is stronger in the middle and northern areas and weaker on the sides and in southern area; currently, the intrusion is relatively serious, and the intrusion area has covered about 68.2% of the areas under study, among which the heavily intruded area is over 50%. Based on the factors analysis of the occurrence and development of sea/saltwater intrusion, the thesis proposes treatment measures.展开更多
The ecosystem-based management of nearshore waters requires integrated assessment of ocean health and scientific guidance on artificial regulations to promote sustainable development. Quantitative approaches were deve...The ecosystem-based management of nearshore waters requires integrated assessment of ocean health and scientific guidance on artificial regulations to promote sustainable development. Quantitative approaches were developed in this paper to assess present and near-term ocean health based on ecosystem services. Results of the case study in the Laizhou Bay of China showed that the index score of ocean health was 0.785 6 out of 1.0 at present and was expected to range from 0.555 1 to 0.804 1 in the near-term future depending on different intensities of artificial regulation of negative pressures. Specifically, the results of ocean health at present mainly indicated that cultural services and provisioning services performed essentially perfectly while supporting services and regulating services functioned less well. It can be concluded that this nearshore ecosystem would partially lose supporting and regulating services in the near-term future if the increasing pressures were not wellregulated but that all of these categories of ecosystem services could be slightly improved if the negative pressures were fully controlled. Additionally, it is recommended that publicity and education on ecosystem services especially on cultural services and regulating services should be further strengthened. The analytical process and resulting quantification provide flexible tools to guide future development of regulations so as to facilitate ecosystem-based management in the coastal zone.展开更多
The distributions of chlorophyll a concentration, primary production and new productionwere observed in the Laizhou Bay of the Bohai Sea in both spring and neap tides during July 1997. The results showed that there we...The distributions of chlorophyll a concentration, primary production and new productionwere observed in the Laizhou Bay of the Bohai Sea in both spring and neap tides during July 1997. The results showed that there were marked features of spatial zonation in the surveyed area, due to the differences between the geographic environment and the hydrological conditions. Chlorophyll a, primary production and new production were all higher in spring tides than that in neap tides in the Laizhou Bay. The highest values of these parameters were encountered in the central regions of the bay. At most stations, chlorophyll a concentrations at the bottom were higher than that at the surface. The results of size-fractionated chlorophyll a and primary production showed that contributions of nanocombining pi-coplankton ( <20 μm) to total chlorophyll a and primary production were dominant in phytoplankton community biomass and production of the Laizhou Bay. The environmental factors, primary production and new production in the Laizhou Bay are compared with other sea areas.展开更多
Through the geochemical analysis of two hundred-meters cores KD4 and ZK3 from Laizhou Bay,in this study,we determined the distribution law and controlling factors of the geochemical elements.We analyzed 24 elements wi...Through the geochemical analysis of two hundred-meters cores KD4 and ZK3 from Laizhou Bay,in this study,we determined the distribution law and controlling factors of the geochemical elements.We analyzed 24 elements with respect to their R factors and major principal components,which were combined with the source discrimination functions DFCr/Th and DFCa/Al to obtain the sediment source index and its variation with depth for this area.A comparison of the changes in climate indicators suggests a clear correlation between the source and climate changes.The results show that the Yellow River and surrounding short-term rivers are the main sediment sources in this area.The PC3 of the KD4 core and PC2 of the ZK3 core(e.g.,CaO,MnO,SiO2)exhibit significant variations and reflect the relative contributions of Yellow River sources.The deposition process can be divided into six stages:in Phase I(MIS 5c–MIS 5a),the Yellow River formed,and the composition of the Yellow River had a greater influence on the sedimentary composition of the study area.In Phase II(MIS 5a–MIS 3),the sediment sources of the Yellow River and the short-term streams in this area were wavering,with the sediments derived from short-term rivers playing a more important role.In Phase III(MIS 3),with a sharp drop in temperature,the study area was in the process of retreat,and the sediment source changed from the Yellow River to short-term rivers,after which the Yellow River source material remained the main sediment source for the region.A similar process occurred three more times in Phase IV(MIS 3–MIS 2),Phase V(MIS 2–MIS 1),and Phase VI(MIS 1).With changes in climate,especially during alternating sea-land phases,the sediment source varied in marine-terrestrial-marine phases,and the changes are observed as Yellow River source-surrounding provenance-Yellow River source.However,this process of change is not synchronized with the sea-land strata alternation.展开更多
Geochemistry analysis has been done on Core E (37 07' N, 118 55' E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbo...Geochemistry analysis has been done on Core E (37 07' N, 118 55' E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbonate are measured by means of ICP. The results indicate that most of the invariable elements and microelements in Core E show significant changes in the boundary stratotype, and the ratios between elements (Mn/Fe, Sr/Ba, Ti/Al) in particular. So they can be used as characteristic indicator to stratigraphic division of Quaternary. The changes of invariable elements are primarily controlled by the host minerals, and they mainly indicate the provenance as well as the sedimentation and depositional environment. Several elements, such as Fe, Al, Ca, Mg, Mn and Ti, are very sensitive to the provenance and environment. The distribution of microelements differs in four depositional periods: last stage of Middle Pleistocene, last interglacial period, last glacial period and Recent epoch, and especially in the 'cold period' and 'warm period'. The loops in the cycle curves of the most microelements correspond with the sand bed sediments, among which there are six sand units representing 'warm period' sediments, and one representing 'cold period' sediments. The carbonate is on the high side in the aeolian silt sediments formed in the glacial lowering of sea level in Core E, but on the low side in the transgressive sand beds formed in the interglacial period. The content variation of carbonate has a direct bearing on the grain size and the styles of sediments, and is a good indicator to the climate, environment and stratigraphic division.展开更多
Typhoon has an impact on an estuary and coastal environment.However,the present research lacks the detailed description of material transport processes during typhoon passage,such as the transport channels and barrier...Typhoon has an impact on an estuary and coastal environment.However,the present research lacks the detailed description of material transport processes during typhoon passage,such as the transport channels and barriers in the course of material transport and material accumulation area,etc.Therefore,Lagrangian coherent structures(a method developed for describing the transport structure of fluids in recent years)was introduced to investigate and predict the floating material and debris transport process in the Laizhou Bay,Bohai Sea,during typhoon Lekima in 2019.Results show that the Lagrangian coherent structure could well explain the complex flow phenomena in the bay.During the typhoon,the general direction of floating material transport in the Laizhou Bay was anticlockwise.There was a channel for material transport in the northwest and south of the bay,and there are transportation obstacles in the northeast-southwest direction in the middle of the bay.Therefore,the typhoon might worsen the water quality.These results provide references for precise countermeasures to control the formulation of pollution in the Laizhou Bay.展开更多
Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicate...Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicated hydrochemical changing process and the mechanism of fresh groundwater being polluted by saltwater, we conducted long-term observation and hydrochemical analysis at four observing sections of typical salt-fresh water transitional zone. The study indicates that seawater and brine intrusion processes have different hydrochemical features, and that ion exchange and adsorption actions between water and aquifer produce great influence on the intrusion.展开更多
Color measuring is characterized by high resolution,high efficiency,and low cost. The application becomes increasingly common for tracing sediment sources and climate variation. Borehole LZ908 in the south coastal pla...Color measuring is characterized by high resolution,high efficiency,and low cost. The application becomes increasingly common for tracing sediment sources and climate variation. Borehole LZ908 in the south coastal plain of the Laizhou Bay in northeast China,was used,of which the top 54 m containing all marine facies was focused,to test the feasibility of colorimetry as a climate indi-cator using visible light reflectance spectra and L*a*b*measurement results. The results show a good correction between lightness and calcium carbonate content in marine-terrigenous deposits;therefore,these deposits can be used as a proxy to study climate changes. Factor-analysis on the first derivative values of the raw visible light reflectance spectra produced three principal factors corresponding to goethite,organic matter,and hematite. Down hole variations in the three fac-tor scores,lightness,calcium carbonate content,and grain size were quite consistent. Moreover,high lightness and low factor scores in goethite,hematite,and organics indicated glacial regression deposits,while low lightness and high factor scores in goethite,hematite,and organics indicated interglacial transgression deposits.展开更多
Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the sur...Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.展开更多
基金the National Natural Science Foundation of China(Nos.42176234 and 42130403)the Chinese Arctic and Antarctic Creative Program(No.JDXT2018-01)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0402).
文摘The Laizhou Bay(LB)represents a substantial ecological area that is vulnerable to human activities and confronts diverse environmental challenges.This study provides a comprehensive characterization of nutrients,petroleum,heavy metals,and phytoplankton community structure across seven distinct areas in LB.The results indicate relatively high concentrations of NO_(2)-N,SiO_(4)-Si,and NO_(3)-N in the Southwest Laizhou Bay(SWLB)and Huanghe River Estuary(HRE).In contrast,the East Laizhou bay(ELB)and the North of Huanghe River Estuary(NHRE)exhibit the highest concentrations of heavy metals(As,Cr and Hg).The areas with high phytoplankton density and community diversity are mainly located in the SWLB.After adjusting for basic environmental factors,phytoplankton density and Margalef richness index D are significantly associated with nutrients(NO_(3)-N,NO_(2)-N,NH_(4)-N,SiO_(4)-Si),and heavy metal(Cr)concentrations.We highlight that,in addition to Xiaoqinghe River,nutrients brought by the Mihe River in the SWLB and heavy metal(Cr)pollution in the ELB resulting from industrial and mining activities along the coast significantly influence phytoplankton growth and community structure.Therefore,it is recommended that more monitoring and management efforts be focused on these regions in the future.
基金Supported by the National Key Research and Development Program of China(No.2019YFD0900704)the Yantai Key Research and Development Program(No.2019XDHZ097)+2 种基金the National Natural Science Foundation of China(No.42076137)the Natural Science Foundation of Shandong Province(No.ZR2020QD003)the Shandong Key Laboratory of Coastal Environmental Processes,YICCAS(No.2019SDHADKFJJ16)。
文摘We used the Integrated Biological Responses version 2(IBRv2)method to evaluate the biological eff ects of heavy metals in the sediments in Laizhou Bay,China on the benthic goby Acanthogobius ommaturus.In December 2018,gobies and sediments were collected from 15 stations.We measured the activities of defense enzymes and the contents of malondialdehyde(MDA)and metallothionein(MT)in the goby liver as well as the levels of heavy metals in the sediments and goby muscle tissue.Most of the heavy metal concentrations in sediment at each station were below the Class I criteria set by Chinese Standards for Marine Sediment Quality,and the Håkanson ecological risk index suggested low risk for the heavy metals.We found that A.ommaturus could eff ectively accumulate mercury,cadmium,arsenic,and zinc and that the contents of MT and MDA and the activities of glutathione peroxidase and glutathione reductase were suitable biomarkers of heavy metal pollution in this species.The IBRv2 method integrated these four biomarkers and discriminated stations according to heavy metal pollution.Higher IBRv2 values suggested more adverse eff ects in gobies,corroborating more serious heavy metal contamination.The stations with high IBRv2 values and high contents of heavy metals were mainly distributed in the west and northeast parts of the bay.These results show that the IBRv2 approach is a feasible strategy for assessing heavy metal pollution through biological response and biological status and that it can be implemented for environmental monitoring in Laizhou Bay.
基金Supported by the National Natural Science Foundation of China(Nos.41706096,41530962,41771218)the Research Start-up Project of Jiangsu Normal University(No.19XSRX006)the Opening Foundation of Hainan Key Laboratory of Marine Geological Resources and Environment(No.HNHYDZZYHJKF005)。
文摘The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in the reconstruction of historical coastal disasters.We investigated an anomalous sand layer in the Xiliyu Village by the coast of Laizhou Bay,Shandong,from which an extreme event deposit was identified using a multi-proxy approach including grain size distribution,geochemistry,and magnetic susceptibility.This event was dated 2700–3100 a bp,and caused inundation of a large coastal area of Laizhou Bay.By comparing historical records with instrumental data,we believe that the event deposit was generated by a severe storm surge with wind speed of>34.9 m/s.
基金The Joint Funds of the National Natural Science Foundation of China under contract Nos U22A20580 and U2106203the National Natural Science Foundation of China under contract No.41706067the Open Project Program of Key Laboratory of Ecological Warning,Protection&Restoration for Bohai Sea,Ministry of Natural Resources under contract No.2022108.
文摘Naturally occurring radium(^(223)Ra,^(224)Ra,^(226)Ra,and^(228)Ra)isotopes have been widely applied as geochemical tracers in marine environments,especially when estimating the submarine groundwater discharge(SGD).In this sense,the influencing factors and transport mechanism of radium isotope activity in aquifers can be key information for SGD estimation.This work evaluates the adsorption/desorption behavior of^(224)Ra and^(226)Ra in the solid-liquid phase through a leaching experiment and analysis of field data.The results suggested that radium isotope activity was positively correlated with salinity and grain size,in the case of abundant sediments.Through ion analysis,we found that the ions(Na^(+),Ca^(2+),Mg^(2+),and Ba^(2+))exchanged with radium isotopes in the process of transport.A 1-D reactive transport model was established to simulate the transport process of radium isotope in aquifers.The model successfully simulated the variation of radium isotope desorption activity with salinity and was subsequently verified in the field.This study contributes to the understanding of the geochemical behavior of radium isotopes in aquifers and provides guidance for selecting a suitable groundwater endmember in SGD estimation.
文摘The disaster of seawater intrusion seriously affects people's lives and restricts economic development,so the detection and treatment of seawater intrusion is a long-term task.On the basis of field investigation and water quality analysis,according to the change characteristics of apparent resistivity of groundwater after Cl-reaches 250 mg/L,the theoretical basis for the application of high-density resistivity method was determined,and the characteristic values of apparent resistivity for seawater intrusion interfaces in different geological characteristic regions in Laizhou Bay area were determined by typical profile tests.Combined with water quality investigation and other means,profiles for the high-density resistivity method were arranged,and the interfaces between saline and fresh water were accurately divided.
基金The National Basic Research Program of China(973 Program)under contract No.2010CB951200the Marine Public Service Specific Research under contract No.201105020
文摘Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C(AMS14C) and optically stimulated luminescence(OSL) ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7(MIS7), the last interglacial period(MIS5) and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes.
基金This study is supported by the National Natural Science Foundation of China(Nos.U1706220,U1806227,U1906231,and 51909114)the Natural Science Foundation of Shandong Province(No.ZR2019BD016).
文摘Salinity in estuaries has an important influence on sediment deposition,delta formation,and fishery economy.The change of runoff in Yellow River(YR),which is the largest river along the Bohai Sea,has an important effect on the salinity of the sea,particularly in Laizhou Bay.In this study,measured runoff data in Lijin hydrological station from 1950 to 2018 are adopted to examine the change of YR runoff into the sea.The study concludes that the runoff of YR is distributed unevenly throughout the year and the amount of runoff mainly concentrates during the flood season.Results show a decreasing trend at a significant level ofα=0.95,with a range of−6.17×10^9 m^3 yr−1.Three groups of runoff are set by using the Finite-Volume Coastal Ocean Model numerical model to analyze the change of salinity in Laizhou Bay.These modeled effects were compared with water level observations made by Bayuquan,Tanggu,and Penglai gauge stations and salinity surveys conducted by Longkou gauge station.Model results and observations of salinity distributions and coastal water level showed good agreement.We can conclude that the distribution of salinity in Laizhou Bay is high in the east and low in the west.Furthermore,it responded quickly to the change of the runoff from YR.Under conditions of high river discharge,the low-salinity zone increased in horizontal direction and reached the bottom in vertical direction.
基金This study was financially supported by the National Science Foundation of China(NSFC)-Shandong Joint Funds(Nos.U1606404,U1906215)the Ocean Spe-cial Funds for Scientific Research on Public Causes(No.201205001).
文摘Study on morphological changes of a bay can help to identify the effects of anthropogenic activities on coastal environ-ment and guide the exploration of marine resources.In this paper,morphological data including coastline and water areas in five discrete years between 1968 and 2015 were selected and extracted from the remote sensing images and historical marine charts to study the morphological changes in Laizhou Bay(LZB),one of the bays in the southwest of the Bohai Sea.A systematic analysis on spatial variations of the coastline and the surface areas of different types of waters in LZB was conducted.The results showed that the surface area of LZB was decreased by 1253.2km^(2)in the last half century,which is 17.4%of the total in the 1970s.The areas of the natural wetland and the intertidal zone were decreased by 17.2%and 56.1%,respectively,and the average water depth varied from 9.05 m to 8.16m at low tide level from 1968 to 2015.The coastline and shape variations of the bay turned to be complex after the 1980s,and the shape index of LZB showed an increasing trend in more recent years.The centroid of the bay generally migrated to the northeast direction,i.e.,the direction of the center of the Bohai Sea,and the shrinking direction of the bay was consistent with the migration direction of the coastline.The reclamation area during 1968-2015 in LZB was 1201.7km^(2),and 94.1%was in the inter-tidal zone.The overall morphological change of the bay during the last half century was mainly controlled by the coastal reclamation activities,and the Yellow River runoff including the river course change and sediment load variation was also an important control-ling factor.
基金National Natural Science Foundation of China, No.40471122
文摘The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP: 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.
基金The National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers under contract No.U1606404the National Basic Research Program(973 Program)of China under contract No.2015CB453301the National Marine Public Welfare Research Project of China under contract No.201405007
文摘As an important part of the Bohai economic rim,the Laizhou Bay has been stressed by serious eco-environmental problems in recent years.In this study,the Shannon-Wiener index(H′),AZTI’s marine biotic index(AMBI)and the multivariate AMBI(M-AMBI)were used to assess the ecological quality status(EQS)of the Laizhou Bay according to macrobenthos data collected annually in August 2011–2014.The results showed that the overall benthic habitat quality in the Laizhou Bay was assessed as“Good”.However,25%of the samples were classified as“Moderate”,“Bad”or“Poor”status under degraded conditions.Ecological group III(EGIII)species which had a certain tolerance to environmental disturbances had a higher proportion in each station,and most of them had appeared the pollution indicator species Capitella capitata.This indicated that the benthic habitat in the Laizhou Bay had been disturbed and polluted to some extent.The comparison of the three indices evaluation result and the RDA analysis showed that the H′and M-AMBI were more suitable when the relative abundance of the single species was high and the macrobenthic community was significantly imbalanced;when the relative abundance of opportunistic species(EGIV and EGV)was high,the AMBI and M-AMBI could reflected the EQS objectively;in an undisturbed and polluted environment,all the three indices could indicate the benthic habitats quality.In summary,the better correlation between the three indices and environmental factors showed that they were well responsive to the tendency of the benthic habitats quality in the Laizhou Bay.
基金funding by the National Natural Science Foundation of China(41977173)Ministry of Science and Technology of the People’s Republic of China(2016YFC0402801)the China Geological Survey Project(DD20189503).
文摘This study is about the reconstruction of fluvial origins based on the grain size distribution of sediment deposits in the western Laizhou Bay,Bohai Sea,China.Thirteen sediment cores were selected to research sediment characteristics using the Sahu discriminant formula,C-M diagram,and Folk method.The results showed:(1)Bounded by the Guangli River estuary,the north sediment was affected by the water and sand flowing from the Yellow River during different periods.The south sediment came from multi-source rivers under the influence of the Xiaoqing River,Mihe River,and other coastal rivers;(2)the deposited sediments were dated by a clear historical record of the branched channel oscillation combined with the characteristics of the diversion channel,erosion,and regression.The subaqueous delta overlapped during several Yellow River channel runs(1897–1904,1929–1934,1938–1947,1947–1953,1976–1996)and the deposited sediment facies changed(the north tidal flat-abandoned subaqueous delta-lateral delta-delta front);(3)the deposited sediment characteristics can be revealed by studying the branched diversions of the Yellow River and coastal multi-rivers of the past one hundred years.
基金supported by the WATER4COASTS project of Sino-Euro Water Platform“Comparative Studies of Underground Water Management in the Coastal Areas in Southeast Asia”(ADB-RETA 6498)of the Water Fun of Asian Development Bank“Geological Environment Survey and Evaluation in Laizhou Bay”of the Geological Survey of China(CGS-12120113003800)
文摘Understanding the degree of sea/saltwater intrusion in coastal regions is of great significance to treating the intrusion and improving the environment. Based on the character analysis of the sea/saltwater intrusion, five factors were selected in the fuzzy-synthetical evaluation approach to form the index system, so as to evaluate the degree of sea/saltwater intrusion in southern Laizhou Bay. The results show that the sea/saltwater intrusion is stronger in the middle and northern areas and weaker on the sides and in southern area; currently, the intrusion is relatively serious, and the intrusion area has covered about 68.2% of the areas under study, among which the heavily intruded area is over 50%. Based on the factors analysis of the occurrence and development of sea/saltwater intrusion, the thesis proposes treatment measures.
基金The Public Science and Technology Research Funds Projects of Ocean in China under contract Nos 201005008 and201005009the National Natural Science Foundation of China under contract No.41206112
文摘The ecosystem-based management of nearshore waters requires integrated assessment of ocean health and scientific guidance on artificial regulations to promote sustainable development. Quantitative approaches were developed in this paper to assess present and near-term ocean health based on ecosystem services. Results of the case study in the Laizhou Bay of China showed that the index score of ocean health was 0.785 6 out of 1.0 at present and was expected to range from 0.555 1 to 0.804 1 in the near-term future depending on different intensities of artificial regulation of negative pressures. Specifically, the results of ocean health at present mainly indicated that cultural services and provisioning services performed essentially perfectly while supporting services and regulating services functioned less well. It can be concluded that this nearshore ecosystem would partially lose supporting and regulating services in the near-term future if the increasing pressures were not wellregulated but that all of these categories of ecosystem services could be slightly improved if the negative pressures were fully controlled. Additionally, it is recommended that publicity and education on ecosystem services especially on cultural services and regulating services should be further strengthened. The analytical process and resulting quantification provide flexible tools to guide future development of regulations so as to facilitate ecosystem-based management in the coastal zone.
基金This study was supported by the National Natural Science Foundation of China under contract No. 497900102.
文摘The distributions of chlorophyll a concentration, primary production and new productionwere observed in the Laizhou Bay of the Bohai Sea in both spring and neap tides during July 1997. The results showed that there were marked features of spatial zonation in the surveyed area, due to the differences between the geographic environment and the hydrological conditions. Chlorophyll a, primary production and new production were all higher in spring tides than that in neap tides in the Laizhou Bay. The highest values of these parameters were encountered in the central regions of the bay. At most stations, chlorophyll a concentrations at the bottom were higher than that at the surface. The results of size-fractionated chlorophyll a and primary production showed that contributions of nanocombining pi-coplankton ( <20 μm) to total chlorophyll a and primary production were dominant in phytoplankton community biomass and production of the Laizhou Bay. The environmental factors, primary production and new production in the Laizhou Bay are compared with other sea areas.
基金supported by the China Geological Survey Project (Nos. GZH201100202 and DD20160158)the Taishan Scholar Project
文摘Through the geochemical analysis of two hundred-meters cores KD4 and ZK3 from Laizhou Bay,in this study,we determined the distribution law and controlling factors of the geochemical elements.We analyzed 24 elements with respect to their R factors and major principal components,which were combined with the source discrimination functions DFCr/Th and DFCa/Al to obtain the sediment source index and its variation with depth for this area.A comparison of the changes in climate indicators suggests a clear correlation between the source and climate changes.The results show that the Yellow River and surrounding short-term rivers are the main sediment sources in this area.The PC3 of the KD4 core and PC2 of the ZK3 core(e.g.,CaO,MnO,SiO2)exhibit significant variations and reflect the relative contributions of Yellow River sources.The deposition process can be divided into six stages:in Phase I(MIS 5c–MIS 5a),the Yellow River formed,and the composition of the Yellow River had a greater influence on the sedimentary composition of the study area.In Phase II(MIS 5a–MIS 3),the sediment sources of the Yellow River and the short-term streams in this area were wavering,with the sediments derived from short-term rivers playing a more important role.In Phase III(MIS 3),with a sharp drop in temperature,the study area was in the process of retreat,and the sediment source changed from the Yellow River to short-term rivers,after which the Yellow River source material remained the main sediment source for the region.A similar process occurred three more times in Phase IV(MIS 3–MIS 2),Phase V(MIS 2–MIS 1),and Phase VI(MIS 1).With changes in climate,especially during alternating sea-land phases,the sediment source varied in marine-terrestrial-marine phases,and the changes are observed as Yellow River source-surrounding provenance-Yellow River source.However,this process of change is not synchronized with the sea-land strata alternation.
基金This study was supported by the National Natural Science Foundation of China under contract Nos 49776296 and 49894170.
文摘Geochemistry analysis has been done on Core E (37 07' N, 118 55' E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbonate are measured by means of ICP. The results indicate that most of the invariable elements and microelements in Core E show significant changes in the boundary stratotype, and the ratios between elements (Mn/Fe, Sr/Ba, Ti/Al) in particular. So they can be used as characteristic indicator to stratigraphic division of Quaternary. The changes of invariable elements are primarily controlled by the host minerals, and they mainly indicate the provenance as well as the sedimentation and depositional environment. Several elements, such as Fe, Al, Ca, Mg, Mn and Ti, are very sensitive to the provenance and environment. The distribution of microelements differs in four depositional periods: last stage of Middle Pleistocene, last interglacial period, last glacial period and Recent epoch, and especially in the 'cold period' and 'warm period'. The loops in the cycle curves of the most microelements correspond with the sand bed sediments, among which there are six sand units representing 'warm period' sediments, and one representing 'cold period' sediments. The carbonate is on the high side in the aeolian silt sediments formed in the glacial lowering of sea level in Core E, but on the low side in the transgressive sand beds formed in the interglacial period. The content variation of carbonate has a direct bearing on the grain size and the styles of sediments, and is a good indicator to the climate, environment and stratigraphic division.
基金Supported by the National Natural Science Foundation of China(No.41974085)the National Key R&D Program of China(No.2019YFC1408100)。
文摘Typhoon has an impact on an estuary and coastal environment.However,the present research lacks the detailed description of material transport processes during typhoon passage,such as the transport channels and barriers in the course of material transport and material accumulation area,etc.Therefore,Lagrangian coherent structures(a method developed for describing the transport structure of fluids in recent years)was introduced to investigate and predict the floating material and debris transport process in the Laizhou Bay,Bohai Sea,during typhoon Lekima in 2019.Results show that the Lagrangian coherent structure could well explain the complex flow phenomena in the bay.During the typhoon,the general direction of floating material transport in the Laizhou Bay was anticlockwise.There was a channel for material transport in the northwest and south of the bay,and there are transportation obstacles in the northeast-southwest direction in the middle of the bay.Therefore,the typhoon might worsen the water quality.These results provide references for precise countermeasures to control the formulation of pollution in the Laizhou Bay.
基金National Natural Science Foundation of China, No.49871011.
文摘Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicated hydrochemical changing process and the mechanism of fresh groundwater being polluted by saltwater, we conducted long-term observation and hydrochemical analysis at four observing sections of typical salt-fresh water transitional zone. The study indicates that seawater and brine intrusion processes have different hydrochemical features, and that ion exchange and adsorption actions between water and aquifer produce great influence on the intrusion.
基金The National Natural Science Foundation of China under contract No. 40602018the Chinese Offshore Investigation and Assessment ("908" Program) under contract No. 908-01-ZH2the Marine Welfare Research Project under contract No. 200805063
文摘Color measuring is characterized by high resolution,high efficiency,and low cost. The application becomes increasingly common for tracing sediment sources and climate variation. Borehole LZ908 in the south coastal plain of the Laizhou Bay in northeast China,was used,of which the top 54 m containing all marine facies was focused,to test the feasibility of colorimetry as a climate indi-cator using visible light reflectance spectra and L*a*b*measurement results. The results show a good correction between lightness and calcium carbonate content in marine-terrigenous deposits;therefore,these deposits can be used as a proxy to study climate changes. Factor-analysis on the first derivative values of the raw visible light reflectance spectra produced three principal factors corresponding to goethite,organic matter,and hematite. Down hole variations in the three fac-tor scores,lightness,calcium carbonate content,and grain size were quite consistent. Moreover,high lightness and low factor scores in goethite,hematite,and organics indicated glacial regression deposits,while low lightness and high factor scores in goethite,hematite,and organics indicated interglacial transgression deposits.
基金Supported by the Science&Technology Basic Resources Investigation Program of China(No.2018FY100200)the National Natural Science Foundation of China(Nos.U2106205,U1706217)+1 种基金the Global Change and Air-Sea Interaction II(No.GASI-01-ATP-STwin)the National Key Research and Development Project of China(No.2018YFC1407600)。
文摘Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.