Grain size composition and transport of sedimentary organic carbon in the Changjiang River(Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

Surface sediments from the Changjiang River （Yangtze River） Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon （OC） concentration, and stable carbon isotope composition （δ13C）. Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand （〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm） and silt （0.025-0.063 mm） fractions by wet-sieving fractionation methods, and further into silt- （0.004-0.025 mm） and clay-sized （〈0.004 mm） fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions （〈0.025 ram） was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways： one was a result of the Changjiang River Diluted Water （CDW） northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.

楚科奇海百年尺度冻土有机碳的埋藏及其对气候变化的响应

在全球变暖的背景下,北极出现了冻土退化、夏季海冰减少、陆地径流输入增加和沿岸侵蚀加剧等一系列变化。随着全球变暖,封存于冻土中的有机碳(Organic Carbon,OC)正在向海加速迁移和释放,这将影响北冰洋的碳循环的格局,但目前鲜有证据能直接证实这一推论。本文通过分析楚科奇海两根百年尺度沉积岩芯的木质素和碳同位素,讨论了其所埋藏的有机质的来源和剖面变化情况。结果显示楚科奇海柱状沉积物中的有机碳来源于陆生C3植物的草本组织和海洋源生产的混合贡献;沉积物中木质素的绝对含量Σ8呈现上升趋势,证明随着全球变暖,更多的陆源物质被输运到楚科奇海。本研究表明人类活动引起的全球变暖确实增加了冻土有机碳向海的迁移,陆源输入增强导致的木质素含量增加是百年尺度下全球变暖导致冻土融化增强的直接证据。

密切党同人民群众血肉联系的现实挑战和对策

当前,密切党同人民群众血肉联系的实践面临部分党员干部宗旨意识淡薄、廉洁自律意识淡化、不能密切联系人民群众、群众工作方法亟待创新等挑战。在新的“赶考”之路上,密切党同人民群众的血肉联系,必须聚焦现存问题,强化理想信念教育,不断增强宗旨意识,增强党员干部廉洁自律意识,完善党密切联系人民群众的相关制度,创新群众工作方法,推动贯彻全过程人民民主。

象山港水体的磷酸盐及其对赤潮的潜在影响

根据2012年5月和2017年10月在象山港海域的调查结果,研究了象山港磷酸盐的来源、分布和消耗。磷酸盐浓度在两次的调查中均呈现由港顶向湾口逐渐降低的趋势,说明港顶区有较高浓度磷酸盐的输入,可能主要来自生活污水和海水养殖。磷酸盐、硝酸盐和盐度在象山港外湾的分布特征说明长江和钱塘江是外湾水体磷酸盐的一个重要来源;此外,磷酸盐、硝酸盐和盐度在牛鼻山水道和佛渡水道的差异分布说明,陆地径流可能经由佛渡水道向象山港贡献了一部分的磷酸盐。内湾水体的磷酸盐分布受控于内外湾水体混合和浮游植物的同化作用,磷酸盐在水体停留时间较长的内湾发生了明显的消耗,相比于保守混合模型的估算值,磷酸盐在象山港内湾中的净消耗比例在2012年5月和2017年10月分别约为20%和9%。2017年秋季观测到的磷酸盐浓度[(1.88±0.31)μmol/L]与2002-2005年在同季节观测到的结果相比增加超过了50%,N/P值下降明显,这一变化可能会导致象山港内引发藻华的藻类种群发生变化,同时也可能会引发更为严重的赤潮。

白令海及西北冰洋有机质来源与新鲜程度的脂肪酸指示

白令海、西北冰洋等高生产力海域在北冰洋“生物泵”中起到重要作用;海水升温、海冰消退等北极快速变化,将强烈影响该海域“生物泵”的结构与规模,并在沉积物中有机质的来源与新鲜程度上有所体现,可用脂肪酸加以指征。对第五次、第六次中国北极科学考察在以上海域采集的表层沉积物进行脂肪酸含量(以沉积物干重计)及组成分析,结果显示楚科奇海陆架总脂肪酸含量非常高((97.15±55.31)μg/g),白令海盆最低((15.00±1.30)μg/g),加拿大海盆、楚科奇海陆坡、白令海陆架居中(分别为(88.65±3.52)μg/g,(70.35±11.32)μg/g与(38.28±14.89)μg/g)。海源脂肪酸占总脂肪酸比例最高(86.82%±7.08%),陆源次之(8.45%±6.62%),细菌最低(4.63%±2.24%);硅藻指数(16:1ω9/16:0)在楚科奇海陆架(>0.82)、白令海陆架边缘(>0.65)较高,其他区域均较低。脂肪酸结果表明:(1)该海域沉积有机质主要来自海源,陆源贡献小;在北部、南部楚科奇海陆架、白令海陆架边缘,硅藻生物量占主要优势;细菌脂肪酸比例显著低于温暖海域,指示低温抑制细菌活动。(2)楚科奇海陆架区硅藻生产力高、细菌活动弱,新鲜有机质沉降效率高,但对未来海水升温、浮游植物群落变化也较为敏感。(3)加拿大海盆、楚科奇海陆坡的浮游植物群落由绿藻与金藻主导。以上结论说明脂肪酸可指示表层沉积物中有机质的来源与新鲜程度;未来,脂肪酸有望进一步揭示北冰洋“生物泵”对北极快速变化的响应。

Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea,Arctic Ocean

The content of organic carbon （OC） normalized to the specific surface area （SSA） of sediment is widely used to trace variations in OC loading （OC/SSA）. This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea, a typical Arctic marginal sea. Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area. Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River, the slope sediments possess lower OC loading. This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes. The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments. Moreover, shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do. The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea.

Composition of algal pigments in surface freshen layer after ice melt in the central Arctic

Seasonal meltwater input creates a thin freshen layer in surface seawater under ice, which largely shifts the algae assemblages. Our recent observation of photosynthetic pigments in the high Arctic showed that ice bottom and 5 m of seawater under ice contained relatively high concentration of fucoxanthin, while chlorophyll b and lutein were the major diagnostic pigments in ice-water interface and 0 m of seawater under ice. Additionally, a notable change of dominant phytoplankton occurred in the top 5 m of seawater under ice, from chlorophytes-dominated at surface to diatoms-dominated at 5 m depth, which might attribute to the sharp salinity gradient （salinity from 12.5 to 28.1） in the surface seawater under ice. Our results imply that phytoplankton community in surface layer under ice would become more chlorophytes in the future warming Arctic Ocean.

Distribution and Sources of Organic Matter in Surface Sediments of the Northern Bering and Chukchi Seas by Using Bulk and Tetraether Proxies

The organic matter (OM) preserved in Arctic Ocean sediments is of great importance to the global carbon budget. How-ever, works that apply multiple proxies to determine the distribution and concentration of organic carbon (OC) in the surface sedi-ments of the northern Bering and Chukchi Seas remain limited. Here a multiproxy approach based on bulk OM parameters and the branched vs. isoprenoid tetraether (BIT) index was used to investigate the distribution and sources of OM in the surface sediments of the northern Bering and Chukchi Seas. Binary and ternary mixing models were applied to trace the contribution of different OC sources to the total OC in the study area. The δ13C values of the sediments provided by the binary model showed that the proportion of terrestrial OC fell in the range of 27.4%–79.8% (46.2% on average). The BIT index returned the lowest fraction (4.8%–27.3%, 12.0% on average). The ternary mixing model was employed to determine the plant-, soil-, and marine-derived fractions of the total OM. The ternary model showed that 11.5%±6.3%, 31.4%±9.5%, and 57.1%±12.4% of OM in the sediment of the study area was derived from soil, plants, and marine sources, respectively. The differences in OM composition between the west and east sides of the Chukchi Sea were controlled by OM inputs from key water masses (i.e., Anadyr Water and Alaska Coastal Water), river discharge, and the nutrient supply from the Pacific inflow that supports marine productivity.

Response of phytoplankton community to different water types in the western Arctic Ocean surface water based on pigment analysis in summer 2008

Nutrients and photosynthesis pigments were investigated in the western Arctic Ocean during the 3rd Chinese Arctic Research Expedition Cruise in summer 2008. The study area was divided into five provinces using the K- means clustering method based on the physical and chemical characteristics of the sea water, and to discuss the distribution of the phytoplankton community structure in these provinces. CHEMTAX software was performed using HPLC pigments to estimate the contributions of eight algal classes to the total chlorophyll a （TChl a）. The results showed that on the Chukchi Shelf, the Pacific Ocean inflow mainly controlled the Chl a biomass and phytoplankton communities by nutrient concentrations. The high nutrient Anadyr Water and Bering Shelf Water （AnW and BSW） controlled region have high Chl a levels and the diatom dominated community structure. In contrast, in the region occupied by low-nutrient like Alaska Coastal Water （ACW）, the Chl a biomass was low, with pico- and nano-phytoplankton as dominated species, such as prasinophytes, chrysophytes and cryptophytes. However, over the off-shelf, the ice cover condition which would affect the physical and nutrient concentrations of the water masses, in consequence had a greater impact on the phytoplankton community structure. Diatom dominated in ice cover region and its contribution to Chl a biomass was up to 75%. In the region dose to the Mendeleev Abyssal Plain （MAP）, controlled by sea-ice melt water with relatively high salinity （MW-HS）, higher nutrient and Chl a concentrations were found and the phytoplankton was dominated by pico- and nano-algae, while the diatom abundance reduced to 33%. In the southern Canada Basin, an ice-free basin （IfB） with the lowest nutrient concentrations and most freshened surface water, low Chl a biomass was a consequence of low nutrients. The ice retreating and a prolonged period of open ocean may not be beneficial to the carbon export efficiency due to reducing the Chl a biomass or intriguing smaller size algae growth.

夏季洪水对长江口及邻近海域颗粒有机碳分布与来源的影响

基于2020年7月洪水期间采集的长江口及邻近海域的温度、盐度、总悬浮物(Total Suspended Matter,TSM)质量浓度、颗粒有机碳(Particulate Organic Carbon,POC)质量浓度和颗粒有机碳稳定同位素(δ^(13)C_(POC))等数据,分析了洪水事件对该区域POC分布与来源的影响。结果显示,研究区域内POC和盐度呈显著负相关(r^(2)=0.41,p<0.01),与TSM呈显著正相关(r^(2)=0.92,p<0.01),表明咸淡水的混合是影响POC分布的重要因素。研究区域东北部表层海水POC质量浓度局部升高,并且δ^(13)C_(POC)值显示为海源信号,表明浮游植物生产是影响该海域POC分布的另一重要因素。此外,由于高径流量形成的稀释效应,洪水事件会降低陆源输入的POC质量浓度,研究区域东南侧偏轻的δ^(13)C_(POC)也表明,洪水事件会扩大陆源POC在东海的影响范围。

Interannual Variations of Phytoplankton, Zooplankton and Chlorophyll a in the Arctic Seas and Their Relations to ENSO and AO

To study effects of variations in climate-marine environment in the Arctic Ocean on ecology,based on the actual and reestablished data by biomarkers of algae in sediment in 1997,1999,2003,2008,and 2010,the interannual and spatial variations of phytoplankton,zooplankton and chlorophyll a concentration in the Chukchi Sea and the Bering Sea as well as their relations to El Nino-Southern Oscillation( ENSO) and Arctic Oscillation( AO) were analyzed. The results show that there were spatial and temporal anomalies in the phytoplankton community structure reestablished by biomarkers of algae in the Chukchi Sea and the Bering Sea in 1999 and 2010. The total content of biomarkers( brassicasterol,dinosterol,C37 alkenones and chlesterol) in sediment collected in 2010 was far lower than that in 1999,but brassicasterol was dominant in the two years,that is,diatom was dominant,which was consistent with the actual structure and distribution of phytoplankton community in 1999 and 2010; there were great changes in the dominant species of plankton in the two seas in 1999 and 2010,which could be regarded as the ecological response of the North Pole under the background of global warming. Chlorophyll a concentration in the water of the Bering Sea was 0. 720 μg/dm^3 at 0 m and 0. 765μg/dm^3 at 10 m in 1997 and 0. 723 μg/dm^3 at 0 m and 0. 731 μg/dm^3 at 10 m in 2003,and the concentration was very close to each other,which was affected by El Ni1 o and the negative phase of AO. It was 0. 395 μg/dm^3 at 0 m in 1999 and 0. 399 μg/dm^3 at 0 m and 0. 357 μg/dm^3 at 10 m in 2008,which was influenced by La Ni1 a and the positive phase of AO. The phases and intensity of AO and ENSO had various effects on the quantity and dominant species of phytoplankton and zooplankton in the Chukchi Sea and the Bering Sea. During the period of AO with positive or negative phase and El Ni1o( in 1997 and 2003),their combination was favorable to the growth of phytoplankton and zooplankton,while the combination of negative phase of AO and La Nina( in 2010) had adverse effects on the growth of phytoplankton. The combination of AO with positive phase and strong La Nina( in 1999 and 2008) had small effects on phytoplankton community.

Seawater nutrient and chlorophyll α distributions near the Great Wall Station, Antarctica

We examined the influences upon nutrient, temperature, salinity and chlorophyll a distributions in Great Wall Cove（GWC） and Ardley Cove（AC）, near the Chinese Antarctic Great Wall Station, using measurements taken in January 2013 and other recent data. Nutrient concentrations were high, with phosphate concentrations of 1.94（GWC） and 1.96（AC） μmol·L-1, DIN（dissolved inorganic nitrogen） concentrations of 26.36（GWC） and 25.94（AC） μmol·L-1 and silicate concentrations of 78.6（GWC） and 79.3（AC） μmol·L-1. However, average concentrations of chlorophyll a were low（1.29 μg·L-1, GWC and 1.08 μg·L-1, AC）, indicating that this region is a high-nutrient and low-chlorophyll（HNLC） area. Nutrient concentrations of freshwater（stream and snowmelt） discharge into GWC and AC in the austral summer are low, meaning freshwater discharge dilutes the nutrient concentrations in the two coves. Strong intrusion of nutrient-rich water from the Bransfield Current in the south was the main source of nutrients in GWC and AC. Low water temperature and strong wind-induced turbulence and instability in the upper layers of the water column were the two main factors that caused the low phytoplankton biomass during the austral summer.

《共产主义运动中的“左派”幼稚病》中列宁的党建思想及其当代价值

1920年,列宁撰写了《共产主义运动中的“左派”幼稚病》一书,全面总结了俄共(布)领导革命的基本经验,揭示了一些西欧国家在共产主义运动中所犯的“左”的错误及其根源。书中列宁关于党的建设思想的主要内容包括:无产阶级政党要发挥好先锋队作用,密切联系群众,加强自身建设。重温本书中列宁关于党的建设的论述,有助于我们坚定马克思主义的指导地位、坚持推进马克思主义中国化时代化、坚持党的群众路线、坚定不移全面从严治党。

Comparison of Phytoplankton Communities Between Melt Ponds and Open Water in the Central Arctic Ocean

Climate warming has a significant impact on the sea ice and ecosystem of the Arctic Ocean.Under the increasing numbers of melt ponds in Arctic sea ice,the phytoplankton communities associated with the ice system are changing.During the 7th Chinese National Arctic Research Expedition cruise in summer 2016,photosynthesis pigments and nutrients were analyzed,revealing differences in phytoplankton communities between melt ponds and open water in the central Arctic.Photosynthetic pigment analysis suggested that Fuco(5-91μg m^-3)and Diadino(4-21μg m^-3)were the main pigments in the open water.However,the melt ponds had high concentrations of Viola(7-30μg m^-3),Lut(4-59μg m^-3)and Chl b(11-38μg m^-3),suggesting that green algae dominated phytoplankton communities in the melt ponds.The significant differences in phytoplankton communities between melt ponds and open water might be due to the salinity difference.Moreover,green algae may play a more important role in Arctic sea ice ecosystems with the expected growing number of melt ponds in the central Arctic Ocean.

延安时期党的自我革命实践与当代启示论析

中国共产党的百年历史,可谓是一部激浊扬清的自我革命史。延安时期作为党历史上的重要时段,党的自身建设水平得到了显著提高。中国共产党基于当时的国情和革命任务,以壮士断腕、刀刃向内的勇气在全党范围内从思想、政治、组织、作风四个方面进行了深入的自我革命实践。新时代推进党的自我革命需要与马克思主义中国化时代化同向发力、贯彻以“政治建设为统领”的方针、充分发挥组织路线的作用、贯彻“三个务必”的作风要求。

十八大以来中国共产党消解脱离群众危险的新探索

人民群众是我们党的执政之基、力量之源,群众资源是我们党须臾不可或缺的执政资源,脱离群众的危险是我们党当前面临的最大危险。十八大以来,中国共产党对于如何消解脱离群众的危险进行了一系列探索,主要包括:开展群众路线教育实践活动,消解党脱离群众的危险;开启全面从严治党新征程,消解党脱离群众的危险;树立以人民为中心的发展思想,消解党脱离人民群众的危险。

在党的建设视角下重思列宁与波格丹诺夫的决裂

列宁与波格丹诺夫的决裂在列宁生平研究、列宁思想史研究中都是一个绕不开的“事件”。从党的建设视角重思列宁与波格丹诺夫的决裂,有助于深化对这一事件本身的认识,也有利于回应西方反列宁主义学者借此事件对列宁的污蔑,并通过将其作为棱镜更好地把握列宁的建党理论。1905年革命后,列宁与波格丹诺夫在党的任务、党的自身建设方向及党的策略上发生了分歧,这些分歧的实质在于二者对马克思主义、对党的性质、对党的基本原则的理解不同,在党的建设上的不同观点加深了二者的分歧并最终导致了组织上的决裂。列宁与波格丹诺夫的决裂启示我们必须正视党内争论、必须警惕党内“小团体”现象、必须勇于批评和自我批评。

中共五大创设监察委员会的原因探赜

党的五大创设监察委员会,是革命时期党的自身建设的伟大壮举,是响应共产国际要求、适应中国共产党发展状况和地位变化、加强党内团结统一的需要,同时中国共产党早期监察工作的实践探索也为创设监察委员会提供了可能。监察委员会的创立,基本确立了党内监督的基本模式,一定意义上加强了党内民主,是大革命时期党的自我革命的突出成果之一。

农村基层党组织群众组织力评价指标体系建构探论

农村群众工作是党提高执政成效、夯实执政根基的基础性工作。建构科学有效的农村基层党组织群众组织力评价指标体系,是为了考量农村基层党组织的建设质量及其组织、动员、领导和凝聚群众等各方面的综合能力,做到心中有“数”。评价指标的设定,应以习近平以人民为中心的思想、农村基层党组织的执政功能以及农村基层党组织组织、动员和服务群众的内聚力与外溢力等为依据,遵循动态性、系统性与导向性的构建原则,建构一个系统化的指标集合。科学评价农村基层党组织群众组织力,对提升农村基层党组织群众工作的制度化水平,建立农村基层党组织与群众之间沟通与反馈的平台,健全农村基层党组织的监督评价机制等具有重要现实意义。

党执政成效的内涵、影响因素及评价论析

执政成效是党在一定的政治生态条件下,利用其可以利用的执政资源获取的执政成果和效益。就其内涵而言,执政成效是党执政成本和执政成果的统一,是党执政能力的集中表现及其自身建设质量的直接反映,体现着党对执政规律认识和把握的程度。影响党执政成效的因素主要包括执政资源、执政成本、执政理念、执政方式和执政能力等。评价党的执政成效主要涉及评价主体、评价指标、评价维度等几个方面的内容。