Response of phytoplankton communities to environmental changes in the Bohai Sea in late summer (2011−2020)

Understanding the dynamics of phytoplankton communities in coastal zones is crucial for the management and conservation of coastal ecosystems.Previous research indicated that the phytoplankton community structure and dominant taxa in the Bohai Sea(BHS)have exhibited significant shifts from the 1990s to the early 2010s in response to environmental changes,especially the change in nutrient structure.This study comprehensively investigated the variations in net-collected phytoplankton(>76μm)community structure,diversity,and environmental factors in the BHS during the late summers of 2011-2020,aiming to understand the recent trend in phytoplankton community structure and to explore the interactions between the communities and the environment.During the study period,the nutrient status in the BHS was characterized by a decrease in dissolved inorganic nitrogen(DIN)concentration,an increase in dissolved inorganic phosphorus(DIP)concentration,and a return of the nitrogen-to-phosphorus(N/P)molar ratio(hereinafter referred to as N/P ratio)to the Redfield ratio since 2016.The eutrophication index(EI)in the BHS remained stable and was generally at a low level(<1).The Dia/Dino index fluctuated but did not show an obvious trend.Overall,the eutrophication,the imbalance in nutrient ratio,and the shift in phytoplankton community structure did not continue during the study period.The increased abundance of phytoplankton was strongly associated with elevated concentrations of DIN,as well as higher N/P and nitrogen-to-silicon(N/Si)ratios,whereas the greater diversity was strongly linked to higher concentrations of DIP.Diatoms and dinoflagellates showed significant differences in their interactions with the environment,and their relative dominance was related to water column depth and stratification intensity;their impacts on the phytoplankton community diversity were also significantly different.The variations of certain dominant species,i.e.,Skeletonema costatum,Paralia sulcata,and Tripos longipes,exhibited strong links to the changes in nutrient structure in the BHS.The findings of this study contribute to understanding the regional environmental changes and provide insights into the adaptive strategies of coastal ecosystems in response to environmental shifts and fluctuations.

Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocated capacities of COD in the Bohai Sea are calculated. For seawater of Grades I to IV of the Chinese National Standard, the ECs of COD in the Bohai Sea were 77×104 t/a, 116×104 t/a, 154×104 t/a and 193×104 t/a, respectively. The Huanghe (Yellow) River pollutant discharge accounted for the largest percentage of COD at 14.3%, followed by that of from the Liugu River (11.5%), and other nine local rivers below 10%. The COD level in 2005 was worse than that of Grade II seawater and was beyond the environmental capacity. In average, 35% COD reduction is called to meet the standard of Grade I seawater.

Pollution Condition of Petroleum Hydrocarbon Pollutant and Estimation of Its Environmental Capacities in Summer in the Bohai Sea

The pollution condition of petroleum hydrocarbon (PH) was summarized in the Bohai Sea in this paper. The results showed that the mean concentration of PH was (25.7±13.6) mg/m3, varying from 4.4 to 64.8 mg/m3 in the survey sea area. Laizhou Bay and Bohai Bay have been contaminated badly inshore. The dynamic model for distribution of marine PH among multiphase environments in the Bohai Sea has been established. The environmental capacities (ECO) and surplus environmental capacities (SECO) of PH have been estimated in the Bohai Sea according to the dynamic model. The results showed that the ECo separately were about 29 169 t/a, 177 306 t/a and 298 446 t/a under the first, second and third, fourth class seawater quality standards requirement. And the ECO of Bohai Bay, Liaodong Bay, Laizhou Bay and Central Bohai Sea were about 5 255 t/a, 8 869 t/a, 4889 t/a and 10 156 t/a respectively under the first and second class seawater quality standards requirement.

Grain-Size Distribution of Surface Sediments in the Bohai Sea and the Northern Yellow Sea: Sediment Supply and Hydrodynamics

The grain-size distribution of surface sediments in the Bohai Sea(BS) and the northern Yellow Sea(NYS), and its relationship with sediment supply and hydrodynamic environment were investigated based on grain-size compositions of surface sediments and modern sedimentation rates. The results showed that the surface sediments in the BS and the NYS were primarily composed of silty sand and clayey silt with a dominant size of silt. In addition, the Yellow River delivered high amount of water and sediments to the BS, and they are dominated in surface sediments(mainly silt) in the Bohai Bay, the Yellow River mouth, the center of the BS, and the north coast of Shandong Peninsula. The coarse-grained sediments were mainly deposited at the river mouth due to the estuarine filtration and physical sorting. Meanwhile, there was a significant relationship among the modern sedimentation rate, the surface sediment grain size distribution and sediment transport pattern. The areas with coarser surface sediments generally corresponded low sedimentation rates because of strong erosion;whereas the sedimentation rate was relatively high at the place that the surface sediments were fine-grained. Furthermore, the grain-size trend analysis showed that the areas with fine-grained surface sediments such as the mud area in the central BS and the upper Liaodong Bay were the convergent centers of surface sediments, except for the Bohai Bay and the subaqueous Yellow River Delta where offshore sediment transport was evident.

Heavy metals in surficial sediments of the central Bohai Sea:their distribution,speciation and sources

The semi-enclosed Bohai Sea has received large amount of pollutants from surrounding rivers and sewage channels along the densely populated and industrializing Bohai coasts,as well as the offshore oil exploration in the sea.The concentrations of heavy metals copper,cobalt,nickel,zinc,lead,chromium and cadmium in 25 surface sediment samples from the central Bohai Sea are obtained by ICP-MS analysis.The speciation of these heavy metals is extracted and their distribution,fractionation,pollution status and sources are presented.High concentrations of copper,cobalt,nickel,zinc and chromium are found in the sediments off the coastal area of the Bohai Bay and the central Bohai Sea mud,while high concentrations of cadmium and lead are found in the sediments in the whole study area.The residual fraction is the dominant form of copper,cobalt,nickel,zinc and chromium in the surface sediments,while cadmium and lead have large proportions in the nonresidual fractions.The ecological risk assessment shows that the sediments in the study area are unpolluted with respect to the heavy metals of cobalt,nickel and chromium and unpolluted to moderately polluted with respect to copper,zinc,cadmium and lead.Cobalt,nickel and chromium mainly have natural origin and their concentrations significantly vary with the composition of the sediments.The contents of copper,zinc,lead and especially cadmium in sediments are suggested to be influenced by pollutants of human activities.The heavy metals in the surface sediments at most sampling stations are mainly come from the Huanghe River; the heavy metals in the sediments in the northernmost part of the study area are significantly affected by the sediment from the Luanhe River; while in the Bohai Bay and the central region they were affected by the sediment from the Haihe River and aerosol deposition.

Assessing impact of oil spills in fairways in Chinese Bohai Sea with the impact matrix method

The density of traffic in Bohai Sea of China is growing,so the evaluation of the impact of potential oil spills becomes necessary.However,the impact of potential oil spills at a large temporal-spatial scale has seldom been studied.In this paper,the effects of potential oil spills in seven main fairways in Chinese Bohai Sea and the risks of five environmental sensitive areas(ESAs)being polluted are studied.A three-dimensional hydrodynamic model,coupled with Lagrangian particle tracking model,was constructed to simulate the transportation of oil spills.Hypothetical oil particles with an idealized,passive tracer were released along fairways and their transportation over20-day and180-day periods were simulated,respectively.An environmental impact matrix was built to reveal the relationship between oil spills in fairways and the pollution of ESAs.Results showed that in short term,Z4and Z5had high risk of being polluted by oil spills.Oil particles released along Fairways1,2and7had strong pollution effects.In long term,Z1,Z3,Z4and Z5had medium risk of being polluted.Oil particles released along Fairway3had strong pollution effects.This study might provide useful data to support marine environment protection.

Ocean Disaster Reduction and Sustainable Development in the Region around Bohai Sea

With the high speed development of the marine economy in the region around the Bohai Sea, a series of disasters that are mainly caused or aggravated by human factors have occurred. They are the severe environment pollution of partial marine area, salt water intrusion, coastal erosion, red tide, land surface subsidence, etc.. These human caused ocean disasters as well as natural ocean disasters that are mainly caused by natural factors, such as typhon, windstorm agitation, sea ice, etc., will influence and restrict the sustainable development of the marine resources and environment in this region. In this paper, their characteristics, causes and effects on the sustainable development of the Bohai region are discussed. In order to reduce the ocean disaster and to guarantee the sustainable development of the Bohai region, some countermeasures are suggested. A comprehensive exploitation plan of the Bohai Sea should be prerequisite. The management of the development of the Bohai region should be improved. The protection and renovation of the ocean environment should be strengthened. The construction of coastal engineering projects should be speeded up.

环境因子对渤海强壮滨箭虫四季种群结构的影响

为深入探究环境因子与渤海强壮滨箭虫四季种群结构动态的关系,并进一步丰富近年来渤海海域浮游动物的相关研究,本研究于2018年4月—2019年12月在渤海海区开展4个航次的海洋综合调查工作,对渤海强壮滨箭虫的时空分布以及生长繁殖状况进行了研究,并讨论了温度、盐度、深度以及饵料等环境因子对其种群结构产生的影响。研究结果显示:盐度与强壮滨箭虫的时空分布具有显著的相关性,在28.5~32.7的范围内,盐度的升高对强壮滨箭虫种群增长有抑制作用;温度通过影响强壮滨箭虫的摄食、代谢来影响其季节上的变化;桡足类作为强壮滨箭虫的主要饵料,也是影响强壮滨箭虫生长繁殖的重要因素。

Paleoenvironmental changes during the late Quaternary as inferred from foraminifera assemblages in the Laizhou Bay

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.

Current status and cause analysis of microplastic pollution in sea areas in China

As a new type of pollutants in the marine environment,microplastics have attracted increasing attention from scientific researchers and environmental protection workers in China and abroad.However,for the microplastic pollution in sea areas in China,there are a very limited number of studies on its current status and few reviews of research on the microplastics.This paper reviews the surveys and researches of microplastics in the Bohai Sea,the Yellow Sea,the East China Sea,the South China Sea,and main estuaries in China carried out in recent years and proposes an outlook for future work,aiming to provide research suggestions and solutions for ecological protection against microplastic pollution in sea areas in China.Previous studies have shown that microplastics are widely distributed in water bodies and sediments in sea areas and major estuaries in China.The Pearl River Estuary,in the South China Sea suffers the most serious microplastic pollution,followed by the Bohai Sea.In contrast,the microplastic pollution in the Yellow Sea and the East China Sea is comparatively slight.Microplastics in sea areas in China are mainly fibrous and are concentrated in offshore areas with developed industry and a dense population(especially around estuaries and bays).In addition,they are widely affected by human activities,such as shipping,aquaculture,industry,and sewage discharge.Here the authors suggest unifying measurement units and research methods and developing related standard systems to carry out researches related to microplastics.Furthermore,this paper also suggests further deepening researches on both the source-sink process of microplastics and nanoscale microplastics while enhancing the development and implementation of related policies,aiming to promote researches and control of microplastics in sea areas in China.

渤海海域地质环境稳定性定量评价

渤海地理位置优越,海洋经济发展迫切需要地质环境资料的支撑,现有研究通常分海区开展,缺乏实测资料支持的系统性研究。基于2008—2016年海洋区域地质调查环境地质因素的相关资料,通过网格化处理,量化渤海海域主要环境地质因素的特征参数,建立了以海底地形或底质环境变化类、地层不均衡类、活动构造类为主要评价指标的地质环境稳定性评价指标体系,采用专家-层次分析定权法和模糊数学评价方法对研究区地质环境稳定性进行定量评价研究。结果显示,渤海海域依据地质环境稳定性可划分为差等、较差、中等、较好、优等5级,大部分海域地质环境稳定性总体较好,地质环境稳定性较差的海域占比10.00%,尤其是黄河三角洲周边海域,不稳定环境地质因素活动断层、地震震中、浅层气及与潮流相关的环境地质因素较为集中,危险性较大。研究结果对渤海海域自然资源的开发利用、生态环境保护等具有重要的应用价值,相关定量评价方法可为中国海洋环境地质研究提供借鉴。

无机氮和重金属对渤海不同区域沉积物中厌氧氨氧化菌的影响差异

厌氧氨氧化菌(anaerobic ammonium oxidation,Anammox)是驱动厌氧氨氧化过程、去除海洋沉积物中氮元素的重要引擎。为分析无机氮和重金属对厌氧氨氧化菌的影响,以渤海沉积物中厌氧氨氧化菌为研究对象,采用Illumina高通量测序技术和实时荧光定量PCR技术对渤海13个站位表层沉积物中AMX16S rDNA基因进行检测,分析其群落结构以及重金属含量对群落结构和多样性的影响。结果表明,渤海沉积物中厌氧氨氧化菌类群可归为14门、8纲、9目、5科、8属、26种,其中浮霉菌门(Planctomycetota)在渤海沉积物中占主导地位,且在中部区域丰度最高;相对丰度最高的属为Candidatus Scalindua。沉积物中重金属Hg在南部区域浓度最高。随机森林分析结果显示,南部区域厌氧氨氧化菌群落结构变化可能与沉积物中的NH4+、Hg和Cr含量密切关联,在北部区域可能与Pb含量密切相关,而在中部区域可能与NO2-含量密切相关。AMX16S rDNA丰度与重金属Cr和Cu、总氮以及沉积物粒度显著正相关(P<0.05)。研究表明,渤海具有丰富的微生物资源和厌氧氨氧化菌,具有代谢多种污染物的潜力。研究结果为认识近海污染对微生物的地理分布格局、群落生态位分化提供了依据。

基于环境DNA宏条形码的辽东半岛重要河口鱼类多样性特征

为了从分子技术水平探讨渤海与北黄海重要河口鱼类构成及多样性分布情况,利用环境DNA宏条形码技术对渤海与北黄海的12个重要河口进行了鱼类群落多样性研究。结果表明:渤海海域共检测出鱼类74种,隶属于2纲19目41科57属,其中,鲈形目(45%)占比最大,北黄海共检测出鱼类76种,隶属于2纲19目42科59属,其中鲈形目(42%)占比最大;渤海与北黄海鱼类多样性指数变化趋势相似,但渤海的多样性指数低于北黄海,表明北黄海具有较丰富的鱼类多样性;基于Bray-Curtis距离的NMDS分析和ANOSIM检验显示,渤海与北黄海鱼类群落组间差异大于组内差异(P=0.001);相比于传统鱼类多样性调查方法,环境DNA宏条形码调查在灵敏性、非破坏性和成本效益方面具有显著优势,适用于鱼类多样性调查。研究表明,北黄海相较于渤海具有更高的鱼类多样性;环境DNA宏条形码技术适用于鱼类多样性调查,可对渔业资源调查结果进行补充,在鱼类多样性调查中具备大范围业务化应用前景。

渤海海域夏季石油烃污染状况及其环境容量估算

根据调查分析了渤海海域石油烃污染状况,建立了渤海石油烃多介质动力学模型,估算了渤海海域石油烃污染物环境容量和剩余环境容量.结果表明,调查海域石油烃平均浓度为(25.7±13.6)mg/m3,变化范围为4.4～64.8 mg/m3,其中,莱州湾,渤海湾等近岸海域污染较严重.在一、二类国家海水水质标准下,渤海海域石油烃污染物环境容量(ECo)为29 169 t/a,在三类国家海水水质标准下ECo为177 306 t/a,在四类国家海水水质标准下ECo为298 446 t/a,各海域在一、二类国家海水水质标准下石油烃污染物环境容量分别为,渤海湾5 255 t/a,辽东湾8 869 t/a,莱州湾4 889t/a,渤海中部10 156t/a.

渤海围填海发展趋势、环境与生态影响及政策建议

近年来,中国沿海处于快速工业化和城市化驱动下的新一轮大规模围填海阶段,环渤海围填海历史久、规模大,已成为我国围填海的重心区域。由于围填海和河口三角洲增长,1940s以来渤海面积萎缩了0.57×104km^2,萎缩速率大于82km2/a,2000年以来萎缩速率更高达141km^2/a;渤海自然岸线的长度和比例也急剧下降,由1990年的1397km减少为2014年的561km,占岸线总长度的比例由54.92%下降为16.18%。围填海导致多种危害,如:海洋潮波和水动力条件变化,近岸和近海沉积环境与水下地形变化,加剧近岸水环境与底泥环境污染,潮滩湿地面积减损与生态功能下降,底栖生物栖息地减损和群落破坏,侵占和破坏渔业资源"三场一通道",加剧海岸带自然灾害风险、诱发经济社会系统风险,对产业和经济发展带来不利影响,等。在分析我国围填海监督管理现状和问题的基础上,提出政策建议:改革和优化围填海管理体制,建立陆海协调与联动机制,完善法律法规;严格执行生态红线制度,控制围填海规模与速度,推进和优化保护区建设;开展已围填区及其周边海域环境和生态的恢复与重建;强化已围填区新增土地资源的监管和集约优化利用;加强基础观测体系建设,大力促进科学研究的发展;促进公众、利益相关方及非政府组织参与到滨海湿地的保护。

渤海春季浮游细菌分布与生态环境因子的关系

研究了 1 999年 4～ 5月渤海水体浮游细菌分布与生态环境因子的关系。结果显示 ,渤海春季表层水体浮游细菌含量与水温和溶解性有机碳呈正相关 ,相关系数分别为 0 .6 0 1 (P<0 .0 1 )和0 .4 0 6 (P<0 .0 5 ) ,并与溶解氧含量呈负相关 ,相关系数为 0 .5 1 9(P<0 .0 1 ) ;底层水体浮游细菌含量与水温、溶解性有机碳 (dissolved organic carbon,DOC)、颗粒性有机碳 (particulate organic carbon,POC)和叶绿素 a含量呈正相关 ,相关系数分别为 0 .82 0 (P<0 .0 1 ) ,0 .6 6 1 (P<0 .0 1 ) ,0 .5 31 (P<0 .0 1 )和 0 .4 42 (P<0 .0 5 ) ,并与溶解氧含量呈负相关 ,相关系数为 0 .6 5 0 (P<0 .0 1 )。表明水温和DOC、POC含量是渤海水域浮游细菌含量的主要限制因子 ,而水体中的溶解氧 (dissolved oxygen,DO)

渤海COD与石油烃环境容量计算

总结评述海洋环境容量计算的3类方法，分析了它们的适用条件和不足之处，并对最优化法加以改进计算了渤海的环境容量。然后用HAMSOM模式模拟了渤海的流场，用SPM模式模拟了渤海的浓度场，计算了渤海的COD和石油烃环境容量。渤海在Ⅰ～Ⅳ类海水水质标准下的COD环境容量分别为36．59×10^4 t／a，54．88×10^4 t／a，73．13×10^4 t／a和91．45×10^4 t／a；在Ⅰ～Ⅳ类海水水质标准下的石油烃环境容量分别为2．82×10^4 t／a，16．86×10^4 t／a和28．17×10^4 t／a。

渤海COD入海通量估算及其分配容量优化研究

在系统分析环渤海地区各种污染源的基础上,估算了1979～2005年渤海COD的入海通量,并基于宏观环境-经济分配容量模型,对渤海COD的环境容量进行了优化分配。结果表明,自20世纪70年代末至今,渤海COD入海通量总体上“M”形变化趋势,年均入海通量180.4万t/a。渤海COD排海总量主要来源于以入海河流为主的陆源排放,高达72.3%;环渤海13个城市中,营口排放所占比例最大高达13.6%,沧州仅为2.5%。在一类水质标准条件下,2005、2010年13城市COD排放均需不同程度的削减,平均削减15.7%和38.3%;在二类水质标准条件下,除2010年潍坊和滨州2市需削减外,其他城市COD排放均满足海洋环境容量的要求。

东海陆扰海域铜、铅、锌、镉重金属排海通量及海洋环境容量估算

汇总并分析了20世纪80年代初以来东海陆扰海域重金属排海通量年变化规律及主要来源,应用多介质海洋环境中重金属迁移-转化模型,估算了东海陆扰海域重金属海洋环境容量。20世纪80年代初以来,东海陆扰海域铜、铅、锌、镉排海总量整体上呈不对称的倒"U"形变化趋势,基本符合"环境库兹涅茨曲线",20世纪90年代达到最大值,当前排海总量仍高于20世纪80年代初期的水平。东海陆扰海域铜、铅、锌、镉污染物主要来源于以河流为主的陆源排放,其中88.0%左右来源于河流排放,7.5%左右来源于排污口,只有4.5%左右来源于大气沉降。长江流域排海通量占东海陆扰海域排海总量的比例最大,平均为92.4%左右,钱塘江流域平均只有3.9%左右,闽江流域平均只有3.7%左右。东海陆扰海域铜、铅、锌、镉污染物海洋环境容量分别约为17.0,4.7,113.1,0.71 kt/a。当前铅、锌、镉污染物排海总量没有超过东海陆扰海域海洋环境容量,但铜的排海总量超过其海洋环境容量大约8%。

渤海南部S_3孔晚第四纪海相地层的划分及环境演变

根据微体化石、粒度、孢粉、粘土矿物和碳酸钙含量等多项分析资料，以及古地磁、１４Ｃ和ＥＳＲ等项测年资料，划分出７个海相地层，它们是：中更新世中、晚期的Ｈ７（４１７．０～４６０．０ｋａＢ．Ｐ．）和Ｈ６（１５７．５～２３１．３ｋａＢ．Ｐ．）海相层；晚更新世前半期末次间冰期的Ｈ５（１００．６～１２４．３ｋａＢ．Ｐ．）和Ｈ４（７６．５～８７．６ｋａＢ．Ｐ．）海相层，末次冰期里两间冰阶的Ｈ３（５８．２～６７．４ｋａＢ．Ｐ．）和Ｈ２（２８～３６ｋａＢ．Ｐ．）海相层，以及冰后期的Ｈ１（８．５ｋａＢ．Ｐ．以来）海相层。其中Ｈ７为渤海海底最新确定的年代最老的海相层。以Ｓ３孔为主，与渤海中部的ＢＣ－１孔和西部的辛集孔对比。