西北太平洋山间盆地沉积物有机碳质量累积速率及影响因素

海洋碳汇作用是大洋生态系统的重要生态系统服务功能,不仅影响着海洋生态系统的能量流动,也是元素循环的重要驱动力。本文以中国大洋48航次采集自西北太平洋典型海山区海盆的沉积物样品和资料为基础,对西北太平洋山间盆地沉积物有机碳质量累积速率(F_orgc)特征及影响因素展开初步研究。结果表明,西北太平洋山间盆地有机碳质量累积速率变化范围为1.41～1.73 g/(m²·ka),均值为1.60 g/(m²·ka),以中部偏西海区的有机碳质量累积速率最高;全区平均净初级生产力转移效率约为0.003 1%。西北太平洋山间盆地有机碳质量累积速率和净初级生产力转移效率均低于东太平洋海区和赤道太平洋海区。本区有机碳质量累积速率受水层和沉积层的生物地球化学循环驱动因素,如海洋净初级生产力、沉积物质量累积速率、有机碳含量、氧化还原电位等的综合影响,同时也受距海山距离、水深等地形因子的影响。     

南昌市厚田剖面末次冰期沉积的色度特征及其古环境意义

色度是古环境重建的重要指标之一,常用于黄土高原黄土古气候重建,但其在亚热带湿润区第四纪沉积中的研究十分少见且意义不明。选取鄱阳湖南岸之厚田沙地的沉积剖面为研究对象,进行了色度测试,结合光释光测年结果,将色度参数与其他气候代用指标进行对比,探讨MIS4—MIS2期间的古气候变化特征。结果表明：各色度参数曲线在剖面垂直方向上产生了较大波动,呈现出干冷→暖湿→干冷的多个冷暖震荡。其中L*值曲线的波峰段主要集中在沙丘砂层（HT6、HT4、HT1）,指示MIS4阶段、MIS3b阶段和MIS2晚期阶段为干燥寒冷的气候环境,冬季风增强;a*、b*、C*和h*值曲线的波峰段主要集中在砂质古土壤层（HT5、HT3、HT2）,指示MIS3c阶段、MIS3a阶段和MIS2早期阶段为温暖湿润的气候环境,夏季风增强,反映了该区域在末次冰期受冬季风和夏季风交替影响的气候演变格局。     

基于沉积速率确定海洋沉积物的监测频率

为建立一套海洋沉积物监测频率的设计方法体系,作者根据中国海洋沉积物趋势性监测的特点和存在的问题,结合国内外海洋沉积物监测方案的设计理论和经验,建立了依据沉积速率确定海洋沉积物监测频率的方法和标准;基于~(210)Pb测年法和IDW空间插值法,绘制了中国监测海域的沉积速率空间分布图,并设计了不同空间尺度的海洋沉积物监测频率优化方案。结果显示,中国近岸区域沉积速率高于远海,河口区域沉积速率高,海湾沉积速率差异显著。其中,沉积速率高于1 cm/a的海域,监测频率为每年1次,如黄河口、长江口等河口区域;沉积速率低于1 cm/a的海域,监测周期为5 a,如渤海中部,黄海、东海远海区域等;个别沉积速率极低的海域,监测周期为10 a,如南沙海域(≤2 cm/1 000 a)。监测频率高的区域主要集中在近岸沉积速率高的海域,而近海和远海沉积速率低的区域监测频率可适当降低。     

太平洋中低纬海水中的二氧化碳分布特征及其与海洋环境条件的关系

根据1986年11月至1990年6月进行的中美热带西太平洋海-气相互作用(TOGA)联合考查和1995年10月至1996年6月“中日副热带联合调查”期间获得的14个航次大气和海水CO₂的观测资料,给出了主要观测海区CO₂的源与汇的分布特征:在赤道地区5°N~5°S,130°~165°E观测到的表面水中二氧化碳分压的值超过了大气中二氧化碳分压1.5~4.5 Pa,结果表明该海区对大气CO₂而言是源,但是该值远小于在中赤道测到的+9.1 Pa和在东赤道太平洋所测的+15 Pa的值.由此表明热带太平洋CO₂源的强度是向西减弱的.副热带海区在秋季对大气CO₂而言是较强的源,春季是汇.对影响海水CO₂变化的主要因素温度、盐度等进行了讨论,表明CO₂的分布变化直接受海流、水团、黑潮和ENSO事件影响.     

Sensitivity analysis of nitrogen and carbon cycling in marine sediments

Biogeochemical cycles in coastal sediments encompass numerous interconnected processes and are sensitive to a high number of external forces. Usually a small subset of these factors is considered when developing state-of-the-art models of marine nutrient cycling. This study therefore aims to assess the degree of complexity required in the model to represent the dependency of major biogeochemical fluxes on both intrinsic as well as external factors. For this, a sensitivity analysis (SA) of the generic Integrated Sediment Model (ISM) was performed comparing two different model setups: 1) a back barrier tidal flat in the German Wadden Sea and; 2) a deep sea site in the Argentine Basin. Both setups were first calibrated to fit pore water profiles of SO₄²⁺, NH₄⁺ and CH₄. We then employed a new type of SA that evaluates parameter impact rather than targeting variable change.General structural stability of the model is demonstrated by similar sensitivity patterns of both setups regarding carbon and nitrogen cycling. Mean temperature, organic carbon bio-availability, bacterial adaptation and sediment texture emerge as the most influential parameters of ubiquitous importance. It appears that in coastal settings, transport and sediment mixing and the composition of suspended particles in the bottom water are especially important. The nitrogen cycle displays a high responsiveness to internal feedback mechanisms as well as interdependencies to carbon and metal cycling, which is statistically reflected by sensitivities to 79% of all parameters. In contrast, the carbon cycle appears to be mainly controlled by organic matter decay. The SA also pointed to unexpected responses of the sediment system, which are analyzed by further scenario calculations. These, for example, reveal a nonlinear response of nitrification, denitrification and benthic fluxes of NH₄ and NO₃ to changing bioturbation and bioirrigation due to the interactions of different metabolic pathways.     

广东沿海及海南岛东南部海底表层孢粉分布及其环境意义

为了探讨海洋表层沉积物的孢粉分布与可能陆源地区植被、气候以及孢粉传播机制的关系,为南海古环境研究提供可靠的基础,采用野外取样、室内实验、计算孢粉百分比和孢粉浓度等方法,对广东沿海及海南岛东南部(108°34′12″—120°E,17°—23°43′12″N,水深为37—3370m)40个表层沉积物样品进行孢粉分析,揭示表层孢粉在整个广东沿海及海南岛东南部的分布和传播规律,尤其关注以往未涉及的广东沿岸海域的孢粉分布情况。研究发现草本花粉如禾本科Poaceae、蒿属Artemisia、藜科Chenopodiaceae、十字花科Brassiceae除在广东沿海近岸带含量较高外,一般都低,可能与沿岸热带亚热带草地分布以及水稻、甘蔗、蔬菜种植有关,推测是以冬季表层环流为动力由北向南传播的。松属Pinus花粉百分比高(20%)且传播较远,以珠江口和东沙群岛附近的样点最高,向西南逐渐降低,说明松属花粉是以冬季风为主要动力传播的。近海区域表层沉积的芒箕孢子含量很高(60%),可能与剧烈的人类活动干扰有关。而热带、亚热带阔叶林花粉(如栲属和栎属)的数量却远远低于其在陆地植被中的数量。广东沿岸的栲属Castanopsis、栎属Quercus、三缝孢Trilete-spore等花粉主要来源于海南岛和广东沿岸,可能是随河流及南海北部表层环流输送的。单缝孢及水生植物莎草科Cyperaceae的百分含量以靠近珠江口的样点较高,可能与河流的注入有关。     

酸洗法测定海洋沉积物有机碳和无机碳含量的致命缺陷

Organic and inorganic carbon contents of marine sediments are important to reconstruct marine productivity,global carbon cycle, and climate change. A proper method to separate and determine organic and inorganic carbons is thus of great necessity. Although the best method is still disputable, the acid leaching method is widely used in many laboratories because of its ease-of-use and high accuracy. The results of the elemental analysis of sediment trap samples reveal that organic and inorganic carbon contents cannot be obtained using the acid leaching method, causing an infinitely amplified error when the carbon content of the decarbonated sample is 12%±1% according to a mathematical derivation. Acid fumigation and gasometric methods are used for comparison, which indicates that other methods can avoid this problem in organic carbon analysis. For the first time, this study uncovers the pitfalls of the acid leaching method, which limits the implication in practical laboratory measurement, and recommends alternative solutions of organic/inorganic carbon determination in marine sediments.     

海洋沉积物光释光测年中环境剂量率测量方法对比分析

光释光测年作为一种沉积物绝对测年方法已在第四纪地质研究中得到了广泛应用,提高光释光测年精度和准确度一直是学术界关注的热点,长期以来人们对等效剂量测量程序和计算方法的研究十分丰富,而对环境剂量率的研究则相对较少。本文以琼西南海域ZBW钻孔岩心样品为例,利用电感耦合等离子质谱/发射光谱法（ICP-MS/OES）、中子活化分析（NAA）、γ谱仪法对海洋沉积物环境剂量率进行了对比测量。结果表明,在部分层段3种方法测量的结果存在差异,其原因为：（1）ICP-MS/OES前处理过程中重矿物中的U不完全溶解;（2）ICP-MS/OES测量结果为U、Th、K元素含量,包含了部分非放射性核素含量;（3）NAA测量用的样品量小,存在偶然性误差,样品中非放射性物质的稀释作用影响测量结果;（4）样品中存在铀系不平衡现象,结合研究区沉积环境和高纯锗γ谱仪测量结果进行对比分析表明,铀系不平衡主要来源于自生铀吸收,对环境剂量率的影响约为11%。     

海洋沉积物微量元素地球化学特征对天然气水合物勘探的指示意义

天然气水合物与资源和全球环境变化等重大科学问题密切相关。前期关于甲烷渗漏区地球化学特征的研究主要集中于浅表层沉积物（＜20 m）,而浅层沉积物（＞20 m）地球化学特征知之甚少。为探讨海洋浅层沉积物微量元素特征与天然气水合物勘探的相关关系,对南海神狐海域沉积物进行了4个站位的钻探取样,分析了样品主、微量元素和有机碳地球化学特征,并采用氧化还原状态以及Mo与TOC相关关系的分析方法进行探讨。结果显示,沉积物主量元素特征主要受到陆源碎屑物质输入的主导,与天然气水合物富集无明显关系。水合物赋存段及附近沉积物中Ba和Mo元素高度富集,存在明显的“Ba峰”和“Mo峰”,主要是由于天然气水合物分解释放大量甲烷产生的硫化环境所导致。因此,沉积物中的Ba和Mo富集特征可作为识别可能存在天然气水合物分布的重要地球化学指标。     

海洋沉积物含水率对部分碱金属及碱土金属元素含量的影响及意义

利用电感耦合等离子体光谱仪(ICP-AES)对海洋表层沉积物及上覆海水、海洋沉积物国家标准物质、陆地的水系沉积物及土壤国家标准物质进行检测以对比海洋沉积物含水率对部分碱金属及碱土金属元素分析结果所造成的影响。结果显示海洋沉积物含水率对钠离子影响最大,往往有超过50%的钠离子来自其中所含海水的贡献,而海洋沉积物含水率对钾、钙、镁的影响则较为微弱。因此,研究海洋沉积物化学组分时有必要考虑其所含海水对钠含量的贡献,以期达到不同海洋沉积物化学组分的可比性。     

Sorption behaviour of benzyl butyl phthalate on marine sediments: Equilibrium assessments, effects of organic carbon content, temperature and salinity

Benzyl butyl phthalate (BBP) is an endocrine-disrupting chemical, and its sorption behaviour on marine sediments was investigated. BBP sorption on the sediments was a rapid process, which could reach equilibrium in 6 h. The sorption equilibrium results could be well described by a linear isotherm. The BBP partition coefficient, K_d, varied from 7.16 to 12.54 L/g in approximately proportion to the organic content of the sediments. After H₂O₂ oxidation for removing the organic material from the sediments, the K_d values were reduced by more than 70%, but the organic normalised partition coefficient averaged 2165 L/g for the H₂O₂-treated sediments, which was more than three times of 598 L/g for the raw sediments. The sorption of BBP on the sediments increased with a decrease in temperature and an increase in salinity. A salting constant of 1.14 L/mol was obtained for BBP in artificial seawater. These research findings are of importance to an assessment of the fate and transport of BBP and other similar endocrine-disrupting chemicals (EDCs) in seawater–sediment systems.     

A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

Organic matter in four Quaternary sediment cores from the Gulf of Mexico and one core from the Washington State coast have been analyzed for lignin and stable carbon isotope compositions. Holocene sequences of all five cores contain organic matter with high relative abundances of ¹³C ($\text{δ}{}^{13}\text{C = ?19.0 to ?22.5\% versus PDB}$) and low lignin concentrations, both of which are consistent with a marine origin. Distinctly lower ¹³C concentrations ($\text{δ}{}^{13}\text{C = ?24.0 to ?25.5\%}$) occur in underlying glacial-age sequences from four of the five cores, including the core from the Washington coast where such trends are previously unreported. Although the carbon isotopic compositions of these Pleistocene sediments are typical of predominantly land-derived organic matter, they contain only about 5% of the lignin found in modern sediments of similar $\text{δ}{}^{13}\text{C}$ from adjacent continental shelves. The lignin-poor organic matter in the glacial-age deposits appears to be either marine-derived or terrigenous material that likely was depleted in vascular plant debris at the time of deposition.     

Improved in situ gamma-ray transmission densitometer for marine sediments

The first-generation University of Illinois gamma-ray transmission densitometer, designed for the in situ measurement of sediment bulk density, was modified by incorporating in the detector probe (1) an Americium-241 alpha particle pulser and an anti-walk gain stabilization control to maintain better temperature stability and (2) a small power supply and a IC preamplifier to eliminate the need for a high-voltage coaxial cable between the detector and external signal conditioning electronics package. This second-generation Lehigh University system has been successfully deployed since 1971 in routine use from ships and submersibles in the Atlantic and Pacific Oceans and the Gulf of Mexico. Results are presented of system operations to (1) measure bulk density over the range of 1.2–1.8 Mg/m³ in the Hudson Canyon, (2) penetrate 1.9 m into the seafloor in the San Diego trough and, (3) be lowered to a water depth of 3.6 km in the Gulf of Mexico.     

The relationship between fatty acid distributions and bacterial respiratory types in contemporary marine sediments

Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment. The fatty acid distribution of a mixed culture of sulphate-reducing bacteria isolated from this system showed a good correlation with the lipid distribution of the zone of maximum sulphate-reduction activity within the sediment. Both distributions had significant concentrations of C14 : 0, iso and anteiso C15 : 0, C16 : 0, C16 : 1ω7 and C18 : 1ω7. This was in contrast to the lipid profile of Desulfovibrio desulfuricans obtained by batch enrichment, which was dominated by iso C17 : 1ω7 fatty acids and correlated poorly with the sediment. The bacterial community cultured from the sediment was further differentiated according to respiratory types (aerobic, facultative aerobic and facultative anaerobic) by growth in a chemostat under defined conditions. The fatty acid distributions of these communities were sufficiently different to enable the various respiratory types to be recognized by their particular fatty acid composition. Cyclopropyl fatty acids (?17 and ?19) were present in significant levels only in the aerobic bacteria, while the facultative aerobes had significantly higher C18 : 1ω7 than the other cultures and the facultative anaerobic community was the only culture to have significant amounts of C12 : 0. The fatty acid distribution of Loch Eil sediment over the range C12-19 seemed to be predominantly of bacterial origin and were relatively abundant to a depth of 6 cm. The concentration of cyclopropyl fatty acids was highest in the oxidized surface sediments and decreased with depth as anaerobic conditions began to dominate, indicating that these fatty acids may only be indicative of aerobic sedimentary bacteria. In contrast to the fatty acids characteristic of bacteria, those fatty acids in the range C20-30 attributed to a terrestrial input were found in relatively constant concentrations over the whole 0–12 cm depth profile.     

海底沉积物纵波速度与强度参数关系模型研究

海底沉积物具有质地松软、强度低的特点,其强度参数与海上平台插桩就位、导管架的安装等工程关系紧密,与海上作业安全息息相关。常规钻孔取芯与静力触探等强度参数获取方法成本较高、取样点少,且对沉积物扰动较大,利用易获取的声学资料预测海底沉积物的强度参数具有重要研究意义。本文基于Wood方程、Biot-Stoll模型、Dvorkin等效介质模型等声波传播理论,计算不同物性参数（密度、孔隙度）梯度下的理论纵波速度,结合室内模拟地层声学实验,对比了模型计算声速与实测声速的变化特征,建立了声速与物性参数关系模型。基于室内模拟地层土力学试验,揭示了沉积物物性与抗剪强度、黏聚力等参数之间的关系,建立了物性与强度参数关系模型。以物性参数为桥梁,建立基于声学特征的海底沉积物强度参数预测模型。此模型既避免了原位取样沉积物失水扰动的问题,又弥补了经验公式局限性的缺点,具有普适性与准确性,有效提高无法取样地区沉积物强度参数的精度,提高了经济效益,对浅层的勘探与开发起到了理论指导的作用。     

Organic matter in deepwater sediments of the Northern Gulf of Mexico and its relationship to the distribution of benthic organisms

Sediment samples were selected from 28 sites across the deep (212–3527 m) northern Gulf of Mexico (GOM) as part of the Deep Gulf of Mexico Benthos (DGoMB) program, and analyzed for geochemical parameters related to organic carbon (OC) distribution and characteristics. The results of this study indicate that the OC content of sediments in the deep northern GOM is controlled by several factors; including water depth, overlying water productivity, sediment carbonate content, sediment oxygen exposure time, OC sources, and regional influences. The best correlation between sediment OC content, on a CaCO₃-free basis, and other parameters examined was an inverse correlation of OC with water depth. The OC/SA ratio had a wide range of values and, along with variable sources of sedimentary OC, indicated that the organism-available concentration of metabolizable organic matter may not be simply related to sedimentary OC content. This was perhaps reflected in the observation that benthic macrofaunal and meiofaunal biomass abundances were well correlated with sedimentary OC, but the abundance of bacteria in sediments was not.     

南日群岛东部海域岩芯沉积物有机碳含量和δ13CTOC值的变化特征及古气候环境意义

2008年在南日群岛东部海域用钻机采集长度为1 004 cm的岩芯样品,测试沉积物中总有机碳（TOC）含量、稳定碳同位素比值（δ13CTOC）、碳氮比值（C/N）、碳酸盐含量以及14C数据,分析其垂直剖面上的变化特征,阐明其沉积环境和古气候的指示意义.沉积物TOC含量变化范围为0.44%～0.74%,垂直剖面上总体显示出末次冰期和全新世中期TOC含量较高,全新世早期相对稳定,而全新世中后期TOC波动范围明显增大.C/N值在5.3～14.9之间变化,平均值为8.1;δ13CTOC值范围为-23.07‰～-21.04‰,表明沉积物中的有机质以海洋自生为主,同时混有部分陆源有机质.碳酸盐含量在3.3%～10.9%之间.TOC含量、C/N比值、δ13CTOC值在岩芯垂直剖面上具有很好的相关性.14C测年数据以及各要素测值在垂直剖面上的变化特征表明：自11 250 aBP以来该海域附近古气候有可能经历了以下4个演化阶段：①11 500～9 000 aBP期间气候寒冷、海平面下降,采样点可能为浅水区或潮间带;②9 000～8 000 aBP期间为升温期,气候由寒冷转向温暖;③8 000～4 300 aBP期间,为相对稳定的暖湿期,在后期气候出现小幅的波动;④4 300 aBP至今,气候进入明显的周期性波动期,暖湿和干冷气候多次交替变化;4 300～3 000 aBP期间为相对寒冷的时期;3 000～1 800 aBP期间为较稳定温暖期,1 800～1 000 aBP期间气温快速降低,标志着研究区进入一个新的寒冷阶段,但是自1 000 aBP以来,气候又再次出现转暖的趋势.     

Organic carbon accumulation and sulfate reduction rates in slope and basin sediments of the Ulleung Basin,East/Japan Sea

This study investigated the organic carbon accumulation rates (OCARs) and sulfate reduction rates (SRRs) in slope and basin sediments of the Ulleung Basin, East/Japan Sea. These sediments have high organic contents at depths greater than 2,000 m; this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. The mean organic carbon to total nitrogen molar ratio was estimated to be 6.98 in the Ulleung Basin sediments, indicating that the organic matter is predominantly of marine origin. Strong organic carbon enrichment in the Ulleung Basin appears to result from high export production, and low dilution by inputs of terrestrial materials and calcium carbonate. Apparent sedimentation rates, calculated primarily from excess ²¹⁰Pb distribution below the zone of sediment mixing, varied from 0.033 to 0.116 cm year⁻¹, agreeing well with previous results for the basin. OCARs fluctuated strongly in the range of 2.06–12.5 g C m⁻² year⁻¹, these rates being four times higher at the slope sites than at the basin sites. Within the top 15 cm of the sediment, the integrated SRRs ranged from 0.72 to 1.89 mmol m⁻² day⁻¹, with rates approximately twice as high in the slope areas as in the basin areas. SRR values were consistently higher in areas of high sedimentation and of high organic carbon accumulation, correlating well with apparent sedimentation rates and OCARs. The sulfate reduction rates recorded in the basin and slope sediments of the Ulleung Basin are higher than those reported for other parts of the world, with the exception of the Peruvian and Chilean upwelling regions. This is consistent with the high organic carbon contents of surface sediments of the Ulleung Basin, suggesting enhanced organic matter fluxes.     

Organic carbon and nitrogen isotopes in surface sediments from the western Arctic Ocean and their implications for sedimentary environments

1 IntroductionFor several reasons, the Arctic Ocean and itsmarginal seas are key areas for understanding ocean-ic circulation and global climate system ( Clark,1982; Hansen et al., 1983; Walsh et al., 1996;Overpeck et al., 1997). First, the Arctic Ocean i…     

北冰洋西部沉积物有机碳、氮同位素特征及其环境指示意义

通过对楚科奇海及邻近的北冰洋深水区表层沉积物中有机碳同位素含量(δ13C)、氮同位素含量(δ15N)及生物成因SiO₂(BSiO₂)含量分析,结果表明海源和陆源有机质的分布受海区环流结构和营养盐结构所制约.楚科奇海中西部和楚科奇海台受太平洋富营养盐海水的影响,海洋生产力高,沉积物中海源有机质和BSiO₂含量高;靠阿拉斯加一侧海域海水的营养盐含量和生产力都偏低,沉积物中陆源有机质比重增加;在研究区北部和东北部的楚科奇高地和加拿大海盆,冰封时间较长,营养盐供应少,海洋生产力低,但来自马更些河和阿拉斯加北部的陆源有机质增多,沉积物中BSiO₂含量小于5%,海源有机质百分含量小于40%.由于亚北极太平洋水通过楚科奇海向北冰洋海盆输送,研究区营养盐池表现为开放系统,营养盐的利用率与它的供应成反比,与海洋生产力成反比.