中国南海表层沉积硅藻的分布及其与环境关系探讨          下载免费PDF全文

孙美琴  蓝东兆  王遹其  薛蕾 《海洋科学进展》2014,32(4)

通过对中国南海62个站位表层沉积硅藻的分析,查明研究海区硅藻的种类组成及分布特点。共鉴定到硅藻56属的235个种(包括变种和变型),以热性外洋种为优势,伴有一定量的近岸广布种。总体上,南海硅藻丰度变化呈现从陆架向陆坡至海盆递增的趋势。根据表层沉积硅藻中具有指示意义的硅藻种的分布和生态变化,划分6个硅藻组合带,各组合分别反映不同的海洋环境,其分布主要受到海洋环流的影响,表现为黑潮暖流、印度洋暖水的入侵以及沿岸流对南海表层沉积硅藻分布的影响。与南海相邻海区硅藻种类比较结果表明,研究海区表层沉积硅藻种类组成与临近的菲律宾海域相似程度最大,其次是中国东海海域、太平洋东北部海域。  相似文献   

渤海湾中部表层沉积物中多环芳烃分布及其来源     

冉涛  李双林  张敏  张念礼 《海洋地质前沿》2014,30(12):30-35

通过对渤海湾中部海域19个站位表层沉积物样品中检测出的13种优控多环芳烃(EPAs)进行同分异构体、甲基菲、GC—MS定量等分析,探讨了研究区沉积物中多环芳烃分布特征、输入来源和污染水平,结果表明,研究区表层沉积物中多环芳烃总含量为2.1~374.8ng/g,平均值为33.1ng/g,多环芳烃总含量呈现出由近岸区向深海区递减的趋势,除最高值BG-60站位外,研究区与其他地区相比污染水平为中—低;化合物组成上以3~4环为主,5~6环次之,从多环芳烃组成以及异构体和甲基菲比值分析表明,研究区沉积物中PAHs以燃烧来源为主,石油类产品和石油化工燃料燃烧贡献最大,煤、木材燃烧贡献次之;高含量的菲和4个高成熟度异常点证实石油烃PAHs污染客观存在。  相似文献   

渤海南部海域柱状沉积物中氮的形态与有机碳的分解   总被引：16，自引：4，他引：16  

马红波  宋金明  吕晓霞 《海洋学报》2002,24(5):64-70

海洋沉积物中氮形态的研究是研究其生物地球化学循环的重要前提,柱状沉积物中氮的形态分布在一定程度上反映了其早期成岩作用的进程及结果.利用分级浸取分离方法首次对渤海南部海域自然粒度下5个柱状沉积物样品进行了分析,依据是否可由试剂提取将其分为可转化态和非转化态,系统地研究了可转化态中各形态氮的分布特征及早期成岩作用.研究表明,渤海南部海域自然粒度下柱状沉积物中,OSF-N和IEF-N是可转化态氮的优势形态.各形态氮的含量随深度变化趋势不同,成岩作用亦不同.沉积物中有机氮的分解速率常数为15.51×10-3a,且对各生源要素的分解速率常数有N>P>C>Si;OC/TN比值远小于OC/ON,说明沉积物中保留了大量无机氮(IN)和非转化的有机氮,OC/ON值随深度增加而减小是由于沉积物中富集了ON;柱状沉积物中,表层比深层可转化态氮占其总量的比例高,在局部区域由于深层沉积物中氮的“再活化”导致二者几乎相同.  相似文献   

巢湖沉积物粒度特征与沉积环境   总被引：9，自引：0，他引：9  

顾成军  戴雪荣  张海林  何小勤 《海洋地质前沿》2004,20(10):10-13

利用巢湖湖底柱样沉积物的粒度资料分析了巢湖湖底沉积物粒径的组成、大小等粒度特征;初步探讨了柱样采样点位置的沉积环境及其沉积过程,以期能为巢湖流域恢复过去环境变化提供参考。通过对沉积物粒度实验分析发现,巢湖靠近河口地区的沉积物粒度在深度上变化幅度大,颗粒物相对较粗,而在湖心位置,沉积物随深度变幅小、连续性好,沉积物的颗粒细。两者的差别分别反映了它们之间不同的沉积环境。  相似文献   

Experiments on the resuspension of estuarine sediments containing benthic diatoms     

V. N. de Jonge  J. van den Bergs 《Estuarine, Coastal and Shelf Science》1987,24(6)

A laboratory system was used to test the effect of water flow on the resuspension of mud and sand sediments and, specifically, benthic diatoms from the Ems estuary, The Netherlands. Current velocities generated by two rotating cylinders in a cylindrical tank were determined by a small float and a laser Doppler velocimeter. At low angular velocities, the amount of suspended matter increased linearly with angular velocity and the float current velocity. However, at higher angular velocities, the increase in current velocity was less because of the strong turbulence: concomitantly, the current velocity boundary layer (δ) became thinner and the suspended matter concentration increased rapidly. The dominant diatom species from the sandy sediment were suspended in two distinct groups, one of which consisted of the species Navicula aequorea, Navicula salinicola, Ophephora martyi and Opephora pacifica, and was more exclusively bound to sand grains than the other. The benthic diatom species inhabiting the silty sediment did not show this difference. The most important shortcoming in the experiments was the inability to determine the radial and vertical velocity components. This precluded reliable calculations of the shear stress. The data presented emphasize the importance of finding a method to determine the shear stress under experiments and field conditions so that direct comparisons can be made. Despite this it is assumed that, just as under the experimental conditions discussed, under natural conditions in shallow waters resuspension starts at current velocities as low as ca. 10 cm s⁻¹.  相似文献   

长江口外沉积物中多环芳烃结构类型的分布   总被引：5，自引：0，他引：5  

唐运千  林壬子 《海洋学研究》1991,9(1):52-59

本文采用色谱—质谱—质谱—计算机系统技术,分析了长江口外两个表层沉积物中多环芳烃组分,并探讨了其有机质的来源和地球化学特征。  相似文献   

黄河落淤治理巨野煤田塌陷区可行性初探   总被引：2，自引：0，他引：2       下载免费PDF全文

黄文峰  朱昶  张洪波  成广宇  张楠 《山东国土资源》2006,22(6):126-129

巨野煤田自南向北呈条带状分布。北依黄河，南接万福河。洙水河、洙赵新河、郓鄄河、郓巨河等黄河支流倾斜穿过矿区，这为大面积利用黄河落淤治理沉陷地区提供了天然的运输河道和动力，通过合理疏通和开挖河道引流落淤并配合使用远距离输沙技术，将使巨野煤田恢复沃野千里成为可能。  相似文献   

Effect of mining and related activities on the sediment trace element geochemistry of lake coeur D'Alene,idaho, USA. Part I: Surface sediments     

Arthur J. Horowitz  Kent A. Elrick  Robert B. Cook 《水文研究》1993,7(4):403-423

During the summer of 1989 surface sediment samples were collected in Lake Coeur d'Alene, the Coeur d'Alene River and the St Joe River, Idaho, at a density of approximately one sample per square kilometre. Additional samples were collected from the banks of the South Fork of the Coeur d'Alene and the Coeur d'Alene Rivers in 1991. All the samples were collected to determine trace element concentrations, partitioning and distribution patterns, and to relate them to mining, mining related and discharge operations that have occurred in the Coeur d'Alene district since the 1880s, some of which are ongoing. Most of the surface sediments in Lake Coeur d'Alene north of Conkling Point and Carey Bay are substantially enriched in Ag, As, Cu, Cd, Hg, Pb, Sb and Zn relative to unaffected sediments in the southern portion of the lake near the St Joe River. All the trace element enriched sediments are extremely fine grained (mean grain sizes « 63 μm). Most of the enriched trace elements, based on both the chemical analyses of separated heavy and light mineral fractions and a two step sequential extraction procedure, are associated with an operationally defined Fe oxide phase; much smaller percentages are associated either with operationally defined organics/sulphides or refractory phases. The presence, concentration and distribution of the Fe oxides and heavy minerals indicates that a substantial portion of the enriched trace elements are probably coming from the Coeur d'Alene River, which is serving as a point source. Within the lake, this relatively simple point source pattern is complicated by a combination of (1) the formation of trace element rich authigenic Fe oxides that appear to have reprecipitated from material solubilized from anoxic bed sediments and (2) physical remobilization by currents and wind driven waves. The processes that have caused the trace element enrichment in the surface sediments of Lake Coeur d'Alene are likely to continue for the foreseeable future.  相似文献   

Directional errors in remanent magnetization of non-cubic soft sediment specimens measured with spinner magnetometers     

William K. Steele 《Geophysical Journal International》1989,96(2):333-341

Summary. This paper assesses theoretically and experimentally the errors in palaeomagnetic directions introduced by measuring rectangular but non-cubic blocks of soft sediments in slow speed spinner magnetometers. Plastic boxes commonly used for this purpose hold samples 21 × 21 × 15 mm. This study models the response of Schonstedt and Molspin spinners to such specimens and presents the results of experiments in which the remanent magnetization (RM) of obsidian blocks, both as cubes and after subsequent cutting to fit within the boxes, was measured to determine actual instrument behaviour. These experiments indicate that the error introduced by use of specimens of the above dimensions may be as much as 8.5° for the smallest specimen-sensor separation in the Schonstedt spinner. For the Molspin spinner and for the next smallest specimen-sensor separation in the Schonstedt instrument, the error is smaller but nevertheless non-negligible.  相似文献   

LOESS IN THE LONGXI BASIN OF GANSU PROVINCE     

文启忠  郑洪汉  韩家懋  王俊达  林绍孟  乔玉楼  魏兰英  刁桂仪 《中国地理科学(英文版)》1991,1(4):370-380

The Nuanquangou loess section in the Longxi Basin has been examined in terms of stratigraphic investigation,. including 14C dating, paleomagnetic polarity, spore-pollen diagram, and mineral and chemical analyses. The results indicate that the section is one of the ancient loess sections with a continuous sedimentation and composed of homogeneous materials with abundant carbonate. The Brunhes / Matuyama boundary and the Jaramillo event were recorded in the section. Stratigraphically,this section can be divided into the Holocene and the Pleistocene loess. The latter includes Malan, Lishi and Wucheng loess in descending order. They were developed at about 1.2 Ma ago, whereas the Nuanquangou loess section possesses some local characteristics different from those observed in other areas.  相似文献