西北太平洋楚科奇海沉积物-水界面营养盐输送通量估算   总被引：2，自引：1，他引：1  

张海舟  庄燕培  朱庆梅  李宏亮  刘小涯  陈法锦  卢勇  陈建芳 《海洋学报》2015,37(11):155-164

陆架区沉积物间隙水的营养盐再生是水体营养盐补充的重要途径之一。楚科奇海陆架区中部沉积物间隙水中的营养盐分布,是物理和生物扰动较弱状态下的沉积物-水界面的典型分布。本文对中国第4次北极科学考察采集的4个多管短柱沉积物样品及多管样站位的上层水样进行分析,得到沉积物间隙水、上覆水以及水柱中营养盐数据。结果表明,沉积物间隙水各营养盐浓度均先随沉积深度增加而呈指数快速升高,记为Ⅰ层;然后进入沉积物再矿化作用与营养盐移出速率相互抵消的稳定变化层,营养盐浓度在该阶段基本不变,记为Ⅱ层;最后是营养盐缓慢递减层,记为Ⅲ层,由于该层有机质降解作用耗尽氧气,NO-3和PO3-4被还原细菌利用而失去氧离子。通过双层模式和Fick第一扩散定律,计算得出楚科奇海沉积物-水界面硅酸盐、磷酸盐和硝酸盐的扩散通量分别为1.660mmol/(m2·d)(以Si计量)、0.008mmol/(m2·d)(以P计量)、0.117mmol/(m2·d)(以N计量)(以R06站为例)。四个调查站位沉积物中硅酸盐的扩散通量分别为3.101mmol/(m2·d)(以Si计量,CC1站)、1.660mmol/(m2·d)(以Si计量,R06站)、1.307mmol/(m2·d)(以Si计量,C07站)、0.243mmol/(m2·d)(以Si计量,S23站),含量呈现明显的纬度分布特征。沉积物间隙水N*的分布表明,楚科奇海沉积环境具有很强的反硝化过程,沉积物脱氮作用是硝酸盐一个重要的汇。  相似文献   

长江口几种优势桡足类对微型浮游动物的摄食研究     

汤宏俊  孙松 《海洋与湖沼》2015,46(1):148-156

利用现场海水培养实验,结合浮游动物网样数据,研究长江口邻近海域几种优势桡足类(中华哲水蚤、背针胸刺水蚤、太平洋纺锤水蚤和精致真刺水蚤)对微型浮游动物的摄食影响。结果表明,精致真刺水蚤虽然属于肉食性种类,但几乎不摄食微型浮游动物;其余三种杂食性桡足类中华哲水蚤、背针胸刺水蚤和太平洋纺锤水蚤对微型浮游动物(纤毛虫+异养甲藻)的摄食率分别为0.66、0.09和0.59μg C/(ind·d),分别占其日总摄食量的29%、24%和37%。其中,异养甲藻在初始生物量和对桡足类饵料贡献上分别占整个微型浮游动物的30%和28%,是微型浮游动物中一个重要的组成类群。中华哲水蚤对微型浮游动物的摄食率与初始食物浓度有显著的正相关关系,并且对体长20μm纤毛虫的清滤率要明显高于对体长20μm的纤毛虫(P0.01)的清滤率,表明其偏好摄食较大个体的食物。通过Chesson选择性指数显示,尽管微型浮游动物在生物量上远小于浮游植物,但桡足类能优先选择摄食微型浮游动物;进一步结合网采浮游动物数据,获得各站三种优势桡足类丰度平均占桡足类总丰度的77%,但它们对微型浮游动物现存生物量的摄食压力仅为0.8%,表明桡足类对微型浮游动物群落的下行控制作用并不明显,仍有大部分微型浮游动物生物量未通过摄食途径进入到桡足类群落中。  相似文献   

2009-2013年普里兹湾表层水体中生物硅的变化及其与气候事件的关系_*     

扈传昱  韩正兵  孙维萍  陈际雨 《海洋与湖沼》2015,46(2)

提要：利用中国南极科学考察期间获得的颗粒物样品,对南大洋普里兹湾海域水体中生物硅的含量分布及年际变化情况进行了分析。研究结果显示：在2013年夏季普里兹湾表层水体中生物硅含量在0.38-8.62μmol/ dm₃之间变化,平均为1.55±1.86μmol/ dm₃。生物硅在表层水体中的空间分布趋势是在67°S以南湾内区域表层水体中的含量明显高于67°S以北的湾外区域,最大值出现在普里兹湾陆架区,生物因子是表层水体生物硅含量分布的主控因子。根据不同年份即25、26、27、28、29次南极科学考察期间获取的数据研究显示,普里兹湾表层水体中生物硅含量存在明显的年际差异。结合历史数据分析表明,气候事件对普里兹湾海冰变化有明显的影响,因而对相应年份该海域浮游植物数量种群结构也会产生一定的而影响,从而导致了表层水体中生物硅含量的年际差异。  相似文献   

Natural background and anthropogenic inputs of polycyclic aromatic hydrocarbons (PAH) in sediments of South-Western Barents Sea     

Stepan Boitsov  H.K.B. Jensen  Jarle Klungsyr 《Marine environmental research》2009,68(5):236-245

Polycyclic aromatic hydrocarbons (PAH) were measured in sediment cores from 13 locations in South-Western Barents Sea as part of a detailed study of the Norwegian seabed under the MAREANO program. The generally low PAH levels found, an average around 200 ng g⁻¹ dry weight for sum PAH, indicate low inputs of petroleum hydrocarbons to the marine environment in the area. Differences in PAH composition and various PAH ratios indicate a natural, mostly petrogenic origin of PAH in sediments from the open sea locations, while the fjord locations show higher pyrogenic PAH contents with an increase towards upper sediment layers, indicating low inputs from human activities. Petrogenic PAH levels increase in deeper sediments at open sea locations, also when normalised to total organic carbon (TOC) contents, suggesting natural leakages of oil-related hydrocarbons in the area.  相似文献   

地幔富硅交代与大陆岩石圈的演化   总被引：4，自引：0，他引：4  

陈立辉  周新华 《地学前缘》2001,8(3):141-146

富硅交代是弧下地幔中熔体岩石相互作用的主要表现形式 ,是造成古老克拉通陆下岩石圈地幔富硅的主要机制。在弧下地幔捕掳体中 ,橄榄岩被来自俯冲洋壳物质部分熔融生成的含水富硅熔体交代后 ,斜方辉石含量的增加使全岩富集SiO2 ,斜方辉石显示异常低的Al2 O3和Cr2 O3,微量元素上表现为强烈富集LILE ,强烈亏损Nb ,Ta和Ti。在古老克拉通地幔岩样品中 ,方辉橄榄岩具过剩的斜方辉石 ,橄榄石的Ni含量与斜方辉石的组成含量成正比 ,而和橄榄石的x(Mg) /x(Mg +Fe2 +)值没有正比关系 ,被解释为亏损的地幔橄榄岩和来自俯冲板片的富硅熔体相互作用的结果。熔体岩石相互作用最终导致了陆下岩石圈地幔富集SiO2 ,这种被含水富硅熔体改造后的地幔岩石的部分熔融可能是造成陆壳富硅富镁的主要原因。含水富硅熔体对岩石圈地幔的影响程度也可能是大陆岩石圈增生或裂解、增厚或减薄的关键因素之一。  相似文献   

硅灰石合成多孔二氧化硅 ——工艺条件与产物性质研究   总被引：4，自引：1，他引：4  

陈庆春  王廷吉  周萍华  彭人勇  CHEN Qing-chun  WANG　Ting-ji  ZHOU Ping-hua  PENG Ren-yong 《华东地质学院学报》2001,24(1):64-66

在一系列硅灰石酸处理实验基础上，研究了产物性质与反应速度、反应时间、中和最终pH值等工艺条件的关系。结果表明，工艺条件不同，物理性质也大不相同。  相似文献   

The role of diagenetic carbonate concretions in the preservation of the original sedimentary record   总被引：1，自引：0，他引：1  

A. El Albani  D. Vachard  W. Kuhnt  & J. Thurow 《Sedimentology》2001,48(4):875-886

The Upper Cretaceous organic rich limestones and marls of the Tarfaya basin of southwest Morocco contain numerous calcite concretions, which formed during early diagenesis. Relative textural similarities are observed both in the concretions and in the host sediments. However, the biological content of the concretions is considerably higher than in the host marls and limestones. Evidence for fossil dissolution in the host marls, and the absence of concretions in some fossil-rich zones, suggest that the difference in fossil abundance between the concretions and host rock is a function of dissolution, rather than preferential precipitation in fossil-rich areas. Consequently, the carbonate concretions appear to represent the 'memory' of the sediment and allow quantification of the original biological components and are potential tools for estimating the original biological material deposited in the soft sediments.  相似文献   

Geochemical processes controlling silica concentrations in groundwaters of the Salado River drainage basin, Argentina   总被引：1，自引：0，他引：1  

P. Miretzky  V. Conzonno  A. Fernndez Cirelli 《Journal of Geochemical Exploration》2001,73(3)

Chemical analyses of dissolved silica in the shallow groundwater of the lower part of the Salado River drainage basin indicate that silica values averaged 60 ppm. The groundwaters are oversaturated in relation to quartz, Na-plagioclase, K-feldspar, and the weathering of quartz and aluminosilicates appear to have little control on silica concentrations in solution. Groundwater is undersaturated with respect to amorphous silica present in the loessic sediments, and these sediments are specially important in the control of the groundwater composition. The sources of amorphous silica are volcanic glass shards and biogenic silica derived from plant (silicophytoliths, diatom frustules) or animal remains (sponge spicules) also present in the Pampean loess. Silicophytoliths and diatoms have also been reported in A soil horizon samples. The dissolution of amorphous silica most likely controls the high dissolved silica concentrations in groundwater.  相似文献   

Rapid formation of rock varnish and other rock coatings on slag deposits near Fontana,California     

Ronald I. Dorn  Norman Meek 《地球表面变化过程与地形》1995,20(6):547-560

Manganiferous rock varnish, silica glaze and iron skins have formed on 20- to 40-year-old slag piles near Fontana, southern California. Rapid rock-varnish formation is associated with an unidentified cocci bacterium that grows rapidly in culturing experiments, combined with the likelihood that Mn-rich solutions flow over slag surfaces. A new model is proposed for the formation of silica glaze, involving soluble Al-Si complexes and the nature of wetting films. Iron skins occur where runoff is concentrated, and where iron bacteria grow. Observations indicate: (i) substrate can be important in supplying Mn, as well as maintaining a stable surface and channelling runoff to microspots where varnish grows; (ii) ignorance of boundary layer pH/Eh conditions makes chemical-physical models of varnish formation speculative; (iii) the balance between cementation of recently nucleated varnishes and erosional shear stresses is poorly understood, but is probably an important limiting factor on varnish growth rates; and (iv) there must be at least two steps in biotic varnishing-accretion of Mn-Fe in casts, followed by cementation of clays by either in situ cast residue or Mn-Fe remobilized from casts. Varnish accretion may be limited by the rate at which both steps occur. Rapid development of readily distinguishable manganiferous rock varnishes at this post-1952 site highlights the danger of speculation on the ages of landforms based solely on the appearance of rock-varnish coatings.  相似文献   

^29Si,^27Al Magic—Angle—Spinning Nuclear Magnetic Resonance（MAS NMR） Studies of Kaolinite and Its Thermal Transformation Products     

He Hongping  Hu Cheng  Guo Jiugao  Zhang Huifen 《中国地球化学学报》1995,14(1):78-82

²⁷Al,²⁹Si MAS NMR studies of kaolinite and its thermal transformation products show that in the kaolinite-mullite reaction series there is an extensive segregation of Al₂O₃ and SiO₂ and the reaction of Al₂O₃ with SiO₂ to form mullite is the main path of mullite formation. At about 850° C, the peak intensity of A1(V) reaches its maximum and with the further rise of temperature the A1(V) signal completely disappears. At about 950°C, γ-Al₂O₃ accounts for about 71% of the material phases containing Al atoms. In the series there is no obvious presence of Al-Si spinel. The²⁷Al and²⁹Si MAS NMR spectra show that there is an obvious difference between the temperature points for Al-O₂(OH)₄ octahedral sheet collapsing and Si-O₄ tetrahedral sheet breaking down.  相似文献