Biomarker Records of Phytoplankton Productivity and Community Structure Changes During the Last 14000 Years in the Mud Area Southwest off Cheju Island, East China Sea

The ecological environment in the East China Sea(ECS)and the Yellow Sea(YS)has changed significantly due to sea-level rising and the Kuroshio incursion since the last deglaciation.In this study,biomarker records of core F10B from the mud area southwest off Cheju Island(MSWCI)were generated to evaluate phytoplankton productivity and community structure changes in response to environmental evolution during the last 14 kyr.The contents of diatom,dinoflagellate and haptophyte biomarkers(brassicasterol,dinosterol and C37alkenones)display similar trends,with increasing phytoplankton productivity during the last 14kyr due to the increased influences of the Kuroshio,and especially due to the eddy-induced upwelling during the late Holocene.On the other hand,the contents of terrestrial biomarkers(C28+C30+C32n-alkanols)and terrestrial organic matter(TOM)proxies(TMBR′and BIT)all reveal decreasing TOM input into the area around the sampling site for the 14 kyr,mostly due to sea-level ris-ing.Phytoplankton biomarker ratios reveal a shift from a haptophyte-dominated community at 6.2 2.5 kyr BP to a diatom-dominated community at 2.5 1.45 kyr BP,likely caused by a stronger cold eddy circulation system at 2.5 1.45 kyr BP in the MSWCI.

Biomarker assessments of sources and environmental implications of organic matter in sediments from potential cold seep areas of the northeastern South China Sea

Multi-biomarker indexes were analyzed for two piston cores from potential cold seep areas of the South China Sea off southwestern Taiwan. Total organic carbon（TOC） normalized terrestrial（n-alkanes） and marine（brassicasterol, dinosterol, alkenones and iso-GDGTs） biomarker contents and ratios（TMBR, 1/Pmar-aq, BIT） were used to evaluate the contributions of terrestrial and marine organic matter（TOM and MOM respectively） to the sedimentary organic matter, indicating that MOM dominated the organic sources in Core MD052911 and the sedimentary organic matter in Core ORI-_（86）0-22 was mainly derived from terrestrial inputs, and different morphologies were the likely reason for TOM percentage differences. BIT results suggested that river-transported terrestrial soil organic matter was not a major source of TOM of sedimentary organic matter around these settings.Diagnostic biomarkers for methane-oxidizing archaea（MOA） were only detected in one sample at 172 cm depth of Core ORI-_（86）0-22, with abnormally high iso-GDGTs content and Methane Index（MI） value（0.94）. These results indicated high anaerobic oxidation of methane（AOM） activities at or around 172 cm in Core ORI-_（86）0-22.However in Core MD052911, MOA biomarkers were not detected and MI values were lower（0.19–0.38）, indicated insignificant contributions of iso-GDGTs from methanotrophic archaea and the absence of significant AOM activities. Biomarker results thus indicated that the discontinuous upward methane seepage and insufficient methane flux could not induce high AOM activities in our sampling sites. In addition, the different patterns of TEX_（86） and U_（37）^（K′） temperature in two cores suggested that AOM activities affected TEX_（86）37 temperature estimates with lower values in Core ORI-_（86）0-22, but not significantly on TEX_（86） temperature estimates in Core MD052911.

Spatial Distributions and Potential Sources of Long Chain(C_(30),C_(32)1,15-)Alkyl Diols in Surface Sediments from Eastern China Marginal Seas

Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g^(-1) for C_(30) diol and 5-669 ng g^(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.

Sources and Transport of Terrigenous Organic Matters Along the East China Sea Inner Shelf: Insights from Lignin and Alkane Biomarkers

The area of East China Sea(ECS)inner shelf is an important sink of suspended particulates from Yangtze River(YR)and materials originated from YR basin.In this study,the parameters of lignin and alkane biomarkers in surface sediment samples from ECS inner shelf were determined to distinguish the sources and to trace the transport of terrigenous organic matters in the region.Our dataset showed that total alkanes with carbon numbers from 10 to 38(T-alkanes)were significantly correlated to both TAR(terrigenous/aquatic ratio)and HMW/LMW(the ratio of high molecular weight to low molecular weight alkanes)(r=0.88,P<0.05 for both),indicating that the majority of T-alkanes was predominantly originated from terrestrial sources,and T-alkanes are important constituents of terrestrial organic matters in the study area.The area was probably affected by petroleum pollution to a certain degree,as indicated by the values of carbon preference index(CPI),odd-over-even carbon number predominance(OEP)and the ratio of pristane to phytane(Pr/Ph).The values of Pr/n-C_(17) and Ph/n-C_(18) suggested a strong reductive sedimentary condition in the region with no obvious biodegradation.The content of eight lignin phenols(Σ8)decreased from the coast to the open sea,indicative of riverine input and hydrodynamic transport of terrigenous organic matters.Lignin degradation parameters presented an increasing trend from the coastline toward the open sea.The lignin vegetation parameters and alkane index(AI)suggested the predominance of non-woody angiosperms in the YR basin.The obvious correlation betweenΛ8(Σ8 normalized to 100 mg organic carbon),TAR and HMW/LMW reveals the significantly concurrent input of lignin and alkanes from terrestrial sources.

Total Maximum Allocated Loads on Stoichiometry of Nitrogen and Identification of Critical Form in Jiaozhou Bay, China

Total pollutant load control management for total dissolved nitrogen(TDN) is an urgent task required to gain a good water quality status in Jiaozhou Bay(JZB), China. In this paper, the stoichiometry of multiform TDN on land-ocean interactions associated with marine biogeochemical reaction(LOIMBR) was studied by modeling the load-response relationship based on a three-dimensional water quality model of nitrogen in JZB. The results showed that the stoichiometry on LOIMBR of dissolved organic nitrogen(DON), NO3-N and NH4-N was 3:1:1, with one-third of the contribution on the concentration of dissolved inorganic nitrogen(DIN) in JZB for the land-based DON loads to DIN loads. Based on the stoichiometric relationship of nitrogen forms, the total maximum allocated load(TMAL) of equivalent TDN(ETDN) was approximately 5300 t a^-1 in JZB, equivalent to the TMAL of 5700, 5800 and 15600 t a^-1 for NH4-N, NO3-N and DON, respectively. According to the loads of ETDN, there were four outfalls overloaded in JZB in 2015, which lie in the head of the bay. In the four overloaded outfalls, besides NO3-N, NH4-N was the critical nitrogen control form for Moshui River, while DON for Dagu River and Haibo River. The results of numerical experiments further showed that JZB will achieve good water quality after 7 years by implementation of the 'different emission reduction' based on TMAL of ETDN, which is significantly better than 'equal percent removal'.

Biomarker Records of Phytoplankton Productivity and Community Structure Changes in the Central Yellow Sea Mud Area During the Mid-Late Holocene

The Yellow Sea(YS)environmental and ecological changes during the Holocene are driven by the interactions between the Yellow Sea Warm Current(YSWC),the East Asian Winter Monsoon(EAWM)and the Kuroshio Current(KC).We report marine biomarker records of brassicasterol,dinosterol and C37 alkenones in core ZY1 and core ZY2 from the South Yellow Sea(SYS)to reconstruct the spatial/temporal variations and possible mechanisms of phytoplankton primary productivity and community structure changes during the Mid-late Holocene.The contents of the corresponding biomarkers in the two cores are similar,and they also reveal broadly similar temporal trends.From 6 kyr to 3 kyr,the biomarker contents in the two cores were relatively low with small oscillations,followed by a distinct increase at about 3 kyr indicating productivity increases caused by a stronger EAWM.The alkenone/brassicasterol ratio(A/B)is used as a community structure proxy,which also showed higher values in both cores since 3 kyr,indicating increased haptophyte contribution to total productivity.It is proposed that the YS community structure has been mainly influenced by the YSWC,with stronger YSWC influences causing an increase in haptophyte contribution since 3 kyr.Some differences of the biomarker records between ZY2 and ZY1 suggest spatial variations in response to YSWC and KC forcing.When the KC was intensified during the periods of 6 4.2 kyr and 1.7 0 kyr,the YSWC extended eastward,exerting more influence on core ZY1.On the other hand,when the KC weakened during 4.2 1.7 kyr,the YSWC extended westward,exerting more influence on the ZY2.

Origins of Terrestrial Organic Matter in Surface Sediments of the East China Sea Shelf

Terrestrial organic matter(TOM) is an important component of marine sedimentary OM, and revealing the origins and transport mechanisms of TOM to the East China Sea(ECS) is important for understanding regional carbon cycle. A novel approach combining molecular proxies and compound-specific carbon isotopes is used to quantitatively constrain the origins and transport mechanisms of TOM in surface sediments from the ECS shelf. The content of terrestrial biomarkers of(C_(27)+C_(29)+C_(31)) n-alkanes(52 to 580 ng g^(-1)) revealed a seaward decreasing trend, the δ^(13)CTOC values(-20.6‰ to-22.7‰) were more negative near the coast, and the TMBR(terrestrial and marine biomarker ratio) values(0.06 to 0.40) also revealed a seaward decreasing trend. These proxies all indicated more TOM(up to 48%) deposition in the coastal areas. The Alkane Index, the ratio of C_(29)/(C_(29)+C_(31)) n-alkanes indicated a higher proportion of grass vegetation in the coastal area; While the δ13C values of C_(29) n-alkane(-_(29).3‰ to-33.8‰) indicated that terrestrial plant in the sediments of the ECS shelf were mainly derived from C_3 plants. Cluster analysis afforded detailed estimates of different-sourced TOM contributions and transport mechanisms. TOM in the Zhejiang-Fujian coastal area was mostly delivered by the Changjiang River, and characterized by higher %TOM(up to 48%), higher %C_3 plant OM(68%-85%) and higher grass plant OM(56%-61%); TOM in the mid-shelf area was mostly transported by aerosols, and characterized by low %TOM(less than 17%), slightly lower C_3 plant OM(56%-72%) and lower grass plant OM(49%-55%).

Application of Principal Component Analysis(PCA)to the Evaluation and Screening of Multiactivity Fungi

Continued innovation in screening methodologies remains important for the discovery of high-quality multiactive fungi,which have been of great significance to the development of new drugs.Mangrove-derived fungi,which are well recognized as prolific sources of natural products,are worth sustained attention and further study.In this study,118 fungi,which mainly included Aspergillus spp.(34.62%)and Penicillium spp.(15.38%),were isolated from the mangrove ecosystem of the Maowei Sea,and 83.1%of the cultured fungi showed at least one bioactivity in four antibacterial and three antioxidant assays.To accurately evaluate the fungal bioactivities,the fungi with multiple bioactivities were successfully evaluated and screened by principal component analysis(PCA),and this analysis provided a dataset for comparing and selecting multibioactive fungi.Among the 118 mangrove-derived fungi tested in this study,Aspergillus spp.showed the best comprehensive activity.Fungi such as A.clavatonanicus,A.flavipes and A.citrinoterreus,which exhibited high comprehensive bioactivity as determined by the PCA,have great potential in the exploitation of natural products and the development of new drugs.This study demonstrated the first use of PCA as a time-saving,scientific method with a strong ability to evaluate and screen multiactive fungi,which indicated that this method can affect the discovery and development of new drugs.

Upwelling and anthropogenic forcing on phytoplankton productivity and community structure changes in the Zhejiang coastal area over the last 100 years

Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores（#34： 28.5°N, 122.272°E; CJ12-1269： 28.861 9°N, 122.515 3°E） from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B（dinosterol/brassicasterol） ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.

Carbon pools and fluxes in the China Seas and adjacent oceans

The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km^2 from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea being a deep basin and part of the Western Pacific Warm Pool is characterized by oceanic features; the East China Sea with a wide continental shelf, enormous terrestrial discharges and open margins to the West Pacific, is featured by strong cross-shelf materials transport; the Yellow Sea is featured by the confluence of cold and warm waters; and the Bohai Sea is a shallow semiclosed gulf with strong impacts of human activities. Three large rivers, the Yangtze River, Yellow River, and Pearl River, flow into the East China Sea, the Bohai Sea, and the South China Sea, respectively. The Kuroshio Current at the outer margin of the Chinese continental shelf is one of the two major western boundary currents of the world oceans and its strength and position directly affect the regional climate of China. These characteristics make the China Seas a typical case of marginal seas to study carbon storage and fluxes. This paper systematically analyzes the literature data on the carbon pools and fluxes of the Bohai Sea,Yellow Sea, East China Sea, and South China Sea, including different interfaces(land-sea, sea-air, sediment-water, and marginal sea-open ocean) and different ecosystems(mangroves, wetland, seagrass beds, macroalgae mariculture, coral reefs, euphotic zones, and water column). Among the four seas, the Bohai Sea and South China Sea are acting as CO_2 sources, releasing about0.22 and 13.86–33.60 Tg C yr^(-1) into the atmosphere, respectively, whereas the Yellow Sea and East China Sea are acting as carbon sinks, absorbing about 1.15 and 6.92–23.30 Tg C yr^(-1) of atmospheric CO_2, respectively. Overall, if only the CO_2 exchange at the sea-air interface is considered, the Chinese marginal seas appear to be a source of atmospheric CO_2, with a net release of 6.01–9.33 Tg C yr^(-1), mainly from the inputs of rivers and adjacent oceans. The riverine dissolved inorganic carbon (DIC) input into the Bohai Sea and Yellow Sea, East China Sea, and South China Sea are 5.04, 14.60, and 40.14 Tg C yr^(-1),respectively. The DIC input from adjacent oceans is as high as 144.81 Tg C yr^(-1), significantly exceeding the carbon released from the seas to the atmosphere. In terms of output, the depositional fluxes of organic carbon in the Bohai Sea, Yellow Sea, East China Sea, and South China Sea are 2.00, 3.60, 7.40, and 5.92 Tg C yr^(-1), respectively. The fluxes of organic carbon from the East China Sea and South China Sea to the adjacent oceans are 15.25–36.70 and 43.93 Tg C yr^(-1), respectively. The annual carbon storage of mangroves, wetlands, and seagrass in Chinese coastal waters is 0.36–1.75 Tg C yr^(-1), with a dissolved organic carbon(DOC) output from seagrass beds of up to 0.59 Tg C yr^(-1). Removable organic carbon flux by Chinese macroalgae mariculture account for 0.68 Tg C yr^(-1) and the associated POC depositional and DOC releasing fluxes are 0.14 and 0.82 Tg C yr^(-1), respectively. Thus, in total, the annual output of organic carbon, which is mainly DOC, in the China Seas is 81.72–104.56 Tg C yr^(-1). The DOC efflux from the East China Sea to the adjacent oceans is 15.00–35.00 Tg C yr^(-1). The DOC efflux from the South China Sea is 31.39 Tg C yr^(-1). Although the marginal China Seas seem to be a source of atmospheric CO_2 based on the CO_2 flux at the sea-air interface, the combined effects of the riverine input in the area, oceanic input, depositional export,and microbial carbon pump(DOC conversion and output) indicate that the China Seas represent an important carbon storage area.

Bio-Organic Geochemistry research in China: Advances,opportunities and challenges

The discipline of "Bio-Organic Geochemistry" is a cross research field between biogeochemistry and traditional organic geochemistry, which focuses on geochemical processes related to the biosynthesis of organic molecules(particularly lipids) by(micro) organisms, organic matter production by primary producers, degradation of organic matter by microbial processes recorded by retainable lipid biomarkers, and organic proxies for studies of paleo-climate, paleo-environments, paleoecology and Earth evolution. This field aims to go beyond the traditional petroleum-oriented Organic Geochemistry by integrating with biogeochemical concepts concerned mostly with biomolecules from cellular material such as DNA and lipids. A formal Chinese organization in Bio-Organic Geochemistry was established in 2012 when the first conference was held in Guangzhou. This organization has witnessed rapid growth over the past six years with focused research addressing organic proxies in paleoclimate and paleoenvironmental applications, with particular rapid development in glycerol dialkyl glycerol tetraethers-derived proxies. Most progresses in China so far are made following or paralleling the international trend in biogeochemical studies. Things have begun to change with China's ambitious initiatives in several bio-geo programs such as the Ocean Deep Drilling Program of China, the Microbial Hydrosphere Program, the Deep Carbon Observatory, and the Microbiome Program. Looking forward in the 21 st Century, the growing Chinese research community in Bio-Organic Geochemistry faces grand opportunities and challenges as Chinese scientists propel themselves toward global research frontiers.

An Introduction to the Special Issue

Shelf seas are important systems supporting China’s rapid economic and societal developments.However,the Yellow Sea(YS)and the East China Sea(ECS)environments have undergone dramatic changes recently,which have profoundly impacted their ecosystem health.Being within the Asian monsoon-dominated region,the environment of the YS and the ECS is influenced by oceanic processes such as the intrusion of the Kuroshio Current(KC)and by human activities of China’s rapidly developed coastal regions.Thus,the YS and the ECS are ideal regions to understand and to distinguish the influences

Study on the simultaneous reduction of methylmercury by SnCl_2 when analyzing inorganic Hg in aqueous samples

Mercury（Hg） is among the most concerned contaminants in the world. It has three major chemical forms in the environment, including Hg0, Hg2＋, and methylmercury（MeHg）. Due to their differences in toxicity, mobility, and bioavailability, speciation analysis is critical for understanding Hg cycling and fate in the environment. SnCl2 reduction-atomic fluorescence spectrometry detection is the most commonly used method for analyzing inorganic Hg. However, it should be noted that MeHg may also be reduced by SnCl2, which would result in the overestimation of inorganic Hg. In this study, the reduction of MeHg by SnCl2 in both de-ionized（DI） water and four natural waters was investigated. The results showed that MeHg could be reduced by SnCl2 in DI water whereas this reaction was hard to occur in tested natural waters. By investigating the effects of water chemical characteristics（dissolved organic matter, pH and common anions and cations） on this reaction, SO42- was identified to be the dominant factor prohibiting SnCl2 induced MeHg reduction in natural waters. SO2-4 in natural waters was evidenced to be reduced to S2- by SnCl2 and the generated S2-can complex with MeHg to form MeHg S-which is hard to be reduced by SnCl2.Findings of this study indicate that the effect of MeHg reduction by SnCl2 on inorganic Hg analysis is negligible in natural waters; however, at simulated experimental systems without SO42-, SO42- should be added as protecting agents to prevent MeHg reduction when analyzing inorganic Hg if it would not cause any other unwanted effects.

Two-Dimensional Borophene:Properties,Fabrication,and Promising Applications

Monoelemental two-dimensional(2D)materials(Xenes)aroused a tremendous attention in 2D science owing to their unique properties and extensive applications.Borophene,one emerging and typical Xene,has been regarded as a promising agent for energy,sensor,and biomedical applications.However,the production of borophene is still a challenge because bulk boron has rather intricate spatial structures and multiple chemical properties.In this review,we describe its excellent properties including the optical,electronic,metallic,semiconducting,photoacoustic,and photothermal properties.The fabrication methods of borophene are also presented including the bottom-up fabrication and the top-down fabrication.In the end,the challenges of borophene in the latest applications are presented and perspectives are discussed.

Black phosphorus-based photothermal therapy with aCD47-mediated immune checkpoint blockade for enhanced cancer immunotherapy

Here,we describe a combination strategy of black phosphorus(BP)-based photothermal therapy together with anti-CD47 antibody(aCD47)-based immunotherapy to synergistically enhance cancer treatment.Tumour resistance to immune checkpoint blockades in most cancers due to immune escape from host surveillance,along with the initiation of metastasis through immunosuppressive cells in the tumour microenvironment,remains a significant challenge for cancer immunotherapy.aCD47,an agent for CD47/SIRPαaxis blockade,induces modest phagocytic activity and a low response rate for monotherapy,resulting in failures in clinical trials.We showed that BP-mediated ablation of tumours through photothermal effects could serve as an effective strategy for specific immunological stimulation,improving the inherently poor immunogenicity of tumours,which is particularly useful for enhancing cancer immunotherapy.BP in combination with aCD47 blockade activates both innate and adaptive immunities and promotes local and systemic anticancer immune responses,thus offering a synergistically enhanced effect in suppression of tumour progression and in inducing abscopal effects for inhibition of metastatic cancers.Our combination strategy provides a promising platform in which photothermal agents could help to enhance the therapeutic efficacy of immunotherapy.