Projection of the Zhujiang(Pearl) River Delta's potential submerged area due to sea level rise during the 21st century based on CMIP5 simulations

Projections of potential submerged area due to sea level rise are helpful for improving understanding of the influence of ongoing global warming on coastal areas. The Ensemble Empirical Mode Decomposition method is used to adaptively decompose the sea level time series in order to extract the secular trend component. Then the linear relationship between the global mean sea level （GMSL） change and the Zhujiang （Pearl） River Delta （PRD） sea level change is calculated： an increase of 1.0 m in the GMSL corresponds to a 1.3 m （uncertainty interval from 1.25 to 1.46 m） increase in the PRD. Based on this relationship and the GMSL rise projected by the Coupled Model Intercomparison Project Phase 5 under three greenhouse gas emission scenarios （representative concentration pathways, or RCPs, from low to high emission scenarios RCP2.6, RCP4.5, and RCP8.5）, the PRD sea level is calculated and projected for the period 2006-2100. By around the year 2050, the PRD sea level will rise 0.29 （0.21 to 0.40） m under RCP2.6, 0.31 （0.22 to 0.42） m under RCP4.5, and 0.34 （0.25 to 0.46） m under RCP8.5, respectively. By 2100, it will rise 0.59 （0.36 to 0.88） m, 0.71 （0.47 to 1.02） m, and 1.0 （0.68 to 1.41） m, respectively. In addition, considering the extreme value of relative sea level due to land subsidence （i.e., 0.20 m） and that obtained from intermonthly variability （i.e., 0.33 m）, the PRD sea level will rise 1.94 m by the year 2100 under the RCP8.5 scenario with the upper uncertainty level （i.e., 1.41 m）. Accordingly, the potential submerged area is 8.57x103 km2 for the PRD, about 1.3 times its present area.

The characteristics of Quaternary activity of faults in the sea area near the Yangtze River mouth

By shallow seismic prospecting, it is showed that the faults in the sea area near the Yangtze River mouth are mainly the NE and NW-trending faults. The main activity time of fault is Pliocene to Early Pleistocene, and the latest activity is up to Middle Pleistocene. The maximum of fault is generally several tens meters with the throw decreased upward. The dislocation near the bottom of Middle Pleistocene is 12~13 m. The average vertical dis-placement rate is on a level of 10-3 mm/a.

Preliminary Study on Cenozoic Group and Fault Activity in the Sea Area Near the Yangtze River Mouth

By shallow seismic prospecting, the Cenozoic Group in the sea area near the Yangtze River Mouth can be divided into five seismic sequences. They correspond to the Quaternary, Pliocene, Upper Miocene, Lower Miocene and Eocene respectively. The Quaternary System covers all the detecting area. The Tertiary System overlaps and thins out from NE to SW. The sedimentary basement mainly consists of volcanic rock (J 3) and acidic rock (r 3 5). Paleogene or Late Cretaceous basins are not found there. The faults that have been detected are all normal faults. They can be divided into three groups (NE, NW, near EW) by their trend. The NE and NW trending faults are predominant, and agree with aeromagnetic anomaly. Their length and displacement are larger than that of the EW trending faults. The activity of the NE trending faults is different in different segments. The SW segment is a Quaternary fault, the middle segment is a Neogene fault, The NE is Paleogene. But the segment of the NW trending fault is not obvious. The average vertical displacement rate is about 0 015mm/a.

Phytoplankton Communities in a Coastal Site of Natural Reserve “Lake of Tarsia-Mouth of River Crati”-Northern Ionian Sea, Calabria (Italy)

Our work was aimed to study the phytoplankton communities in two coastal sites placed in Natural Reserve “Lake of Tarsia-Mouth of river Crati” in Northern Ionian Sea-Calabria (Italy). This zone represents a wetland area of high natural interest populated by different organisms (animals and plants) living in a transitional ecosystem characterized by a great biodiversity. The sampling was performed in two different seasonal periods (summer and autumn 2012) and in two different sites (marine site vs fluvial one). Different algal genera/species were recognized and analyzed by Utermohl inverted microscope method and also qualitative and quantitative measures of biomass were performed. The results showed that the dominant group was the Diatoms with exclusive species in such periods in both the sampling sites;we also observed the presence of genera and/or species of potentially toxic algae (Pseudo-nitzschia sp., Alexandrium taylori, Prorocentrum micans, Skeletonema sp.), mostly in summer. Complessively, the phytoplankton biomass was always higher in marine site than in the fluvial site. The results were also processed considering the context of the chemical-physical parameters (such as temperature, pH, salinity, nutrients). The high concentration of the nutrients N and P in such periods indicated a state of meso-eutrophic waters both in the proximity of river site as well as in the marine zone. The data represent the first contribution to the knowledge of the phytoplankton structure in this area, which results in a very variable environment with a high recovery capacity.

A four-band index for both liquid and solid water and its applications in the Aral Sea Basin

Various investigations have been conducted to analyze the water-coverage area of the Aral Sea and the Aral Sea Basin(ASB). However, the investigations incorporated considerable uncertainty and the used water indices had misclassification problem, which made different research groups present different results. Thus we first ascertain the boundaries of the ASB, the Syr and Amu river basins as well as their upper, middle and lower reaches. Then a four-band index for both liquid and solid water(ILSW) is proposed to address the misclassification problems of the classic water indices. ILSW is calculated by using the reflectance values of the green, red, near infrared, and thermal infrared bands, which combines the normalized difference water index(NDWI) and land surface temperature(LST) together. Validation results show that the ILSW water index has the highest accuracy by far in the Aral Sea Basin. Our results indicate that annual average decline of the water-coverage area was 963 km^(2) in the southern Aral Sea, whereas the northern Aral Sea has experienced little change. In the meanwhile, permanent ice and snow in upper reach of ASB has retreated considerably. Annual retreating rates of the permanent ice and snow were respectively 6233and 3841 km^(2) in upper reaches of Amu river basin(UARB) and Syr river basin(USRB). One of major reasons is that climate has become warmer in ASB. The climate change has caused serious water deficit problem. The water deficit had an increasing trend since the 1990s and its increasing rates was 3.778 billion m^(3) yearly on average. The total water deficit was 76.967 billion m^(3) on average in the whole area of ASB in the 2010s. However, up reaches of Syr river basin(USRB), a component area of ASB, had water surplus of 25.461 billion m^(3). These conclusions are useful for setting out a sustainable development strategy in ASB.

新背景下构建“图们江国际合作大湾区”的思考——以拓展我国图们江出海权为导向

图们江出海权益问题是我国近代以来备受关注的重要历史问题之一。我国拥有图们江出海的相关权利和法理依据,但权益行使却一直跌宕起伏。现阶段,百年大变局下全球秩序面临重构,东北亚局势也呈现出深刻变化,中俄朝政治、经贸合作日益强化。新背景为我国图们江出海权益带来新的契机和挑战。从东北亚格局演进的新背景出发,在充分阐释我国拥有图们江出海的法理依据和相关权利的基础上,主张对我国拥有图们江的相关权益进行整体规划,进而提出新时期构建“图们江国际合作大湾区”开发计划的三个阶段设想,并试图探索现阶段应着手解决的对策建议。

北部湾港平陆运河江海联运方案研究

平陆运河始于西江航运干线中上游的西津枢纽水库支流平塘江口,终于北部湾港,是优化提升全国水运网络、加快建设国家综合立体交通网的联网工程,是建设西部陆海新通道、加快建设交通强国的标志性工程。根据《国家综合立体交通网规划纲要》部署,北部湾港总体规划正在编制,需要统筹考虑平陆运河江海联运枢纽空间布局和平面布置方案。综合考虑平陆运河江海联运量、北部湾港各港区建港条件和资源容量,以及既有港口资源利用情况,按照“就近转运、用足存量”的原则,因地制宜提出分货类的江海联运枢纽布局,制定了大小泊位能力匹配、运输组织高效的平面布置方案,同时也提出明确防城港域航区划分、研究开通防城港水运疏港通道(皇城坳运河)、有序推进现状码头升级改造等建议,为平陆运河建设投产后江海联运平稳运行提供技术支撑。

刁口河河道及局部海域物理模型测控系统研究

淤积、延伸、摆动、改道是黄河口主要演变规律,黄河治理必须给黄河入海留有出路。刁口河作为备用流路、分洪通道、生态补水通道,其战略地位十分突出。因此,借助于物理模型试验手段开展刁口河相关重大问题研究至关重要。针对刁口河河道及局部海域实体物理模型,设计了一套潮汐模拟测控系统。该系统运行可靠、试验精度高,可实现上游流量、下游水位及流向等多边界耦合控制,为黄河治理提供技术支撑。

盐城市近年来入海河流涉氮污染物特征分析

研究以盐城入海河流水质中氮类污染物为研究对象分析相其污染特征,研究表明:盐城市入海河流氨氮浓度均达到地表水Ⅲ类水标准,总氮平均浓度高于湖库总氮标准Ⅴ类标准限值。在2018-2022年连续五年的评价时段内氨氮浓度具有显著下降趋势,总氮浓度指标呈一定的下降趋势,趋势不显著。盐城市入海河流总氮和氨氮月均值均具有春冬季氨总氮浓度水平高于夏秋季的季节性变化的特征。盐城市入海河流涉氮污染物中,硝态氮含量居三氮之首。入海河流总氮和氨氮浓度分布与近岸海域无机氮在时间上和空间上存在明显一致性,陆域污染物入海依然是近岸海域污染的主要来源。

秋冬季浮游植物群落结构特征及其环境因子关系——以珠江口南沙海域为例

为探究珠江口南沙海域浮游植物群落结构特征及其与环境因子的关系,分别于2021年10月(秋季)、2022年2月(冬季)对珠江口南沙海域的浮游植物及海水温度、盐度、营养盐浓度等环境因子进行了调查。结果表明:本次调查共鉴别出浮游植物160种,其中包括硅藻38属96种,甲藻7属19种,裸藻13属16种,绿藻11属13种,蓝藻9属13种,隐藻2种,金藻1种。硅藻为主要类群,占总种数的60%。优势种(Y≥0.02)有8种,硅藻占6种,如颗粒直链藻、美丽星杆藻等。浮游植物细胞丰度季节变化明显,秋季细胞丰度平均为731.39×104 cells/m 3,冬季为75.52×104 cells/m 3。Shannon-Wiener多样性指数(H′)、物种均匀度Pielou′s指数(J′)平均值分别为2.70和0.57。浮游植物细胞丰度与环境因子相关性关系在不同季节差异显著,秋季活性磷酸盐与浮游植物细胞丰度呈极显著正相关关系。

长江口邻近海域大型底栖生物群落结构分析

2004年5月的调查共获大型底栖生物50种,种数和丰度的优势生物为多毛类动物,而底栖鱼类和螠虫的生物量占明显优势。长江口大型底栖生物平均生物量为17.57g/m2,平均丰度为150ind./m2。生物量和丰度密集区集中在盐度25度线附近海域。根据Bray-Curtis相似性系数聚类分析和多维排序尺度分析,长江口大型底栖生物可划分为四个群落:Ⅰ圆筒原盒螺-滩栖阳遂足-棘刺锚参-背蚓虫群落;Ⅱ圆筒原盒螺-钩虾群落;Ⅲ背蚓虫-奇异稚齿虫-不倒翁-尖叶长手沙蚕-近辐蛇尾群落;Ⅳ短叶索沙蚕-长吻沙蚕-纽虫群落。通过引入环境变量的二维MDS图分析,长江口大型底栖生物群落分布与底层盐度、有机物具有较大的相关性。生存环境短时间内的剧烈变化是导致群落Ⅱ和Ⅳ种群贫乏的重要原因之一。河口区悬浮粉砂颗粒的短期快速沉降现象可能也是导致群落Ⅱ和Ⅳ种群贫乏的另一重要原因。

长江口邻近海域赤潮发生区基本特征初探

对长江口邻近海域与赤潮的发生有密切关系、可能影响赤潮生物的生长、迁移、聚集、休眠以及竞争等的一些主要环境特征 ,如流系结构和水团、冲淡水及其转向、上升流、锋面、营养盐的输入及其来源、浮游生物群落特征等进行了综述 ,对该海域赤潮发生的历史记录从时间、地点、赤潮类型等方面作了归纳分析 ,并对 2 0 0 2年在该赤潮发生区开展的现场调查的初步结果作一简略介绍 .

东海赤潮高发区春季溶解氧和pH分布特征及影响因素探讨

根据2002年4月27日—5月2日长江口邻近海域的大面调查,分析了东海溶解氧及pH值的分布特征,并对长江口外溶解氧低值区的成因及其与赤潮发生的关系进行了初步探讨。结果表明,调查海域pH值呈近岸低、外海高的分布趋势,溶解氧整体处于过饱和状态,呈近岸高、外海低的分布趋势。4月下旬在调查海区东南部底层已开始出现溶解氧低值区,面积约为15400km2,该水域表观耗氧量AOU一般在1.50mg/L以上,并伴随有氧的亏损发生,形成原因主要是水交换较弱和有机物分解耗氧。溶解氧低值区可能是有机碎屑的沉降汇集区,随着夏季温度的升高及长江丰水期的到来,有机碎屑有可能在台湾暖流的影响下产生西、北向的爬升而造成溶解氧低值区扩大和溶解氧含量的进一步降低。

长江口海域赤潮成因及其防治对策

对长江口海域的赤潮发生形势进行了系统总结与分析 ,探讨了长江口海域赤潮灾害的成因及其防治对策。长江口及邻近海域是我国赤潮高发区 ,自20世纪80年代以来赤潮发生越来越频繁 ,赤潮生物种类增加 ,2002年首次发生了有毒亚历山大藻(Alexandriumsp.)赤潮 ,赤潮危害程度在增大 ,这与长江口海域的环境和生物条件、河口最大浑浊带、长江上游大型水利工程建设以及全球气候变化对长江口海域赤潮高发区的影响有直接关系 ,同时河口海域甲藻孢囊也是赤潮发生的种源。建议建立赤潮立体监测体系、赤潮信息管理系统、海产品赤潮毒素卫生检疫制度和赤潮应急响应机制 ,全面加强长江口海域的赤潮监控与防治工作。

中国南海北部神狐海域高饱和度天然气水合物成藏特征及机制

基于中国南海北部神狐海域GMGS3钻探区内岩心、测井、二维及三维地震数据综合分析,对黏土质粉砂储集层高饱和度扩散型天然气水合物分布特征、差异聚集机理及其成藏机制进行研究。研究结果表明:高饱和度水合物通常对应着高电阻率、低声波时差,强似海底反射(BSRs),且在BSRs下部可能存在泥底辟及气烟囱等形式的流体渗漏现象;水合物储集层以黏土质粉砂细粒沉积物为主,局部存在具有较高孔渗性的粉砂细粒沉积物;水合物类型以Ⅰ型为主,在Ⅰ型水合物层的底部可能存在Ⅱ型水合物;水合物气源为热解气、微生物气混合成因,来自白云凹陷中心深部的热成因气通过断层和泥底辟及气烟囱向浅层运移并与原位生物气混合,直至运移至水合物温度、压力稳定区域中富集形成高饱和度水合物;流体运移输导系统影响和控制了高饱和度水合物差异聚集成藏。

长江口外海域沉积物中有机物的来源及分布

通过分析长江口外海域不同区域有机碳和氮的分布特征及其影响因素,了解了底部沉积物中有机碳和氮同位素的生物地球化学特征,探讨二者对长江口外海域底部沉积物中有机物来源的指示意义。运用质量混合模型,计算了长江输入的陆源有机物的贡献及其空间变化。结果表明,长江口外海域沉积物中TOC和TN的分布和东海陆架的环流体系有着密切关系,与环流的分布相对应,如果大致沿31oN和123oE作为分界线,整个研究区的TOC和TN的分布可划分为4个具有不同分布特征的区域。TOC、TN、!13C和"15N分别与沉积物的平均粒径呈线性相关关系,因此,粒度效应是控制长江口外海域沉积物中有机物分布和稳定同位素碳、氮的一个重要因素。研究区内的C/N比值能够在一定程度上体现有机物的来源信息,但#15N表现出了与C/N和$13C不同的区域分布和变化特征。陆源有机物来源比重较高的区域与长江口外海域赤潮突发频率最高的地区相对应。长江口附近沉积物中的陆源有机物来源最高,超过了50%,且等值线呈舌状向东北方向凸出,表明了长江冲淡水的影响。陆源颗粒态有机物沉海底后,要不断经历早期成岩作用和生物作用,因此在在相同地点,陆源有机物对沉积物中有机物的贡献,要明显小于对悬浮颗粒态有机物的贡献。

埕岛海域波浪引起不同区域土体的液化程度

收集埕岛海域地区近十余年的地质勘察资料,汇总该区地质灾害的类型及其分布情况,发现该区存在着凹坑、冲沟、滑塌、泥流舌、海底穿刺、粗糙海底和埋藏古河道等地质灾害,在海域西北、中部和东南部均有分布,简要探讨形成机理,计算波浪循环荷载在海床中产生的循环应力比,以及根据标贯击数和黏粒含量建立土体的循环阻抗比,然后,计算不同风浪等级下每个钻孔1m深度处土体抗液化安全系数,采用surfer8.0软件绘制安全系数等值线图。发现抗液化性能较好的区域主要分布在海域中部三块地区,随着风浪等级增大,整个区域内液化面积也逐渐扩大,海域东南地区有少量油井和管线分布,区地质灾害发生频率较高,土体抗液化性能较差,工程设施应重视较大风浪期间土体液化对其安全性能的影响。

珠江口南沙海域浮游植物群落结构特征

基于2015年4月(丰水期)和2015年11月(枯水期)珠江口南沙海域的调查资料,分析该海域浮游植物的种类组成、优势度、细胞丰度及多样性。共鉴定出浮游植物5门44属76种,硅藻为最主要优势种群。丰水期优势种有2种,分别为新月筒柱藻(Cylindrotheca closterium)和中肋骨条藻(Skeletonema costatum);枯水期优势种有3种,分别为萎软海链藻(Thalassiosira mala)、中肋骨条藻和有棘圆筛藻(Coscinodiscus spinosus)。丰水期和枯水期浮游植物细胞丰度分别为651.91×104个·L-1和129.21×104个·L-1,2个时期细胞丰度分布都表现为近岸向离岸递增的趋势。调查海区的浮游植物Shannon-Wiener多样性指数(H')和Pielou均匀度指数(J')的平均值在丰水期分别为1.64和0.40,而在枯水期分别为1.58和0.41,多样性总体处于较低水平。典范对应分析结果表明,丰水期影响浮游植物群落结构的主要环境因子为盐度、温度、总氮和p H,枯水期为温度、透明度、磷酸盐和盐度。

大港滩海地区地震沉积学研究

在井点少、井网不规则的滩海地区,基于井资料的研究方法对储集层研究精度低,难以满足油藏开发研究的需要。在大港埕海油田Ⅰ区开展地震沉积学研究,通过纵向与平面信息相互约束和标定,实现对辫状河心滩单砂层内部结构的细致刻画。对地震资料进行相位转换和地层切片处理,利用切片上的振幅特征对研究区心滩砂体平面分布进行解释,并通过不同深度的地层切片特征研究心滩演化过程。研究发现,研究区馆I1-1小层上部心滩单砂层可以划分为3次洪水期形成的心滩沉积。通过直井和水平井组的解剖研究,验证了地层切片揭示的沉积特征及演化规律,在此基础上建立了研究区沉积模式,对指导研究区水平井开发和无井区储集层沉积特征精细研究具有重要意义。