福建海坛岛青峰老红砂旋回沉积的粒度特征及其古环境意义   总被引：1，自引：0，他引：1  

申健玲  李志忠  靳建辉  邓涛  姜锋  苑秀全  于晓莉  赖海成 《中国沙漠》2016,36(4):972-982

福建海坛岛青峰老红砂剖面以棕红色砂层和黄橙色砂层的交替旋回变化为显著特征。通过野外考察、采样和测定分析,对青峰老红砂剖面的粒度特征及其古气候意义进行深入研究。结果表明：（1）青峰剖面棕红色砂层以细砂为主,黄橙色砂层以中砂为主,细砂-中砂在剖面上呈现明显的交替旋回变化;（2）棕红色砂层和黄橙色砂层的粒度频率曲线均以单峰加一细尾为主,含有一定量的粉砂、黏土;概率累积曲线以滚-跳-悬三段式为主,但两种砂层在组分含量、斜率等方面存在差异;（3）粒度参数呈现明显的波动旋回变化,可能指示沉积时期区域风力、搬运动力、化学风化强度方面发生了周期性变化,即棕红色砂层显示了暖湿气候条件下的红壤化过程,黄橙色砂层则显示凉干气候条件下的黄壤化过程。因此,青峰老红砂旋回沉积表明第四纪晚期以来,福建东部沿海的古气候古土壤可能经历了南亚热带（赤红壤）和暖温带（黄壤）的交替变迁。  相似文献   

快速城镇化背景下海岛农村居民点空间演变——以福建海坛岛为例     

苏木兰  戴文远  黄华富  郭强  黄剑彬 《热带地理》2016,36(6):1005-1018

以平潭综合实验区主岛--海坛岛为研究区,基于 2000、2009 和 2013 年 3 期 SPOT 遥感数据,运用单一土地利用动态度、马尔科夫转移矩阵模型、最近邻点统计量、核密度估计、探索性数据分析和空间“热点”探测方法定量分析海坛岛农村居民点时空分布特征及其演变规律,并从景观生态学角度深入分析农村居民点空间分布特征的影响因素。结果表明：1）2000―2013 年间农村居民点扩张明显,面积共增加 399.69 hm² ,主要转自耕地和林地,后期（2009―2013 年）的增量、增速均比前期（2000―2009 年）大,说明综合实验区的成立对海坛岛农村居民点扩张产生重要影响。2）海坛岛农村居民点扩展主要形式：一是块状扩展,即沿原有斑块向四周蔓延式向外扩展;二是带状扩展,即沿各乡镇的交通干线向两侧或某侧扩展。3）2000、2009 和 2013 年海坛岛农村居民点的空间分布均表现出显著的聚集特征,呈现高密度小规模集聚分布与低密度大规模集聚分布格局,且随时间变化,农村居民点集聚程度不断提高。4）坡度、地形起伏度、道路和河流等景观要素对海坛岛农村居民点的布局有显著影响,农村居民点主要分布在地势平坦、坡度平缓（0~10°）、近水源（距河流＜1 500 m）以及交通便利（距离道路＜500 m）的地方,且扩张趋势明显;反之,农村居民点分布明显较少。  相似文献   

Mathematical modelling of sea water intrusion,Nauru Island     

F. Ghassemi  A. J. Jakeman  G. Jacobson 《水文研究》1990,4(3):269-281

A two-dimensional finite element model for density dependent groundwater flow was calibrated to simulate sea water intrusion in Nauru Island in the Central Pacific Ocean. Nauru Island occupies an area of 22 km² and supports a population of 8500. The island has been mined for its phosphate deposits and current reserves indicate that the mine has about eight years life remaining. The water supply of the island is about one third dependent on imported water which is also used as ballast on the phosphate ships. Imported water will not be available in the future, and a hydrogeological investigation shows that the island is underlain by a fresh water layer, less than 5 m thick. The freshwater layer overlies a thick transition zone of brackish water which in turn overlies sea water. Simulation of several management options shows that it is possible to substitute current importation of fresh water by careful extraction from the groundwater resources of the island.  相似文献   

Denitrification in Qi''ao Island coastal zone, the Zhujiang Estuary in China   总被引：1，自引：0，他引：1  

WANG Hu  ZHOU Huaiyang  PENG Xiaotong  YANG Qunhui  QIN Chaomei  YIN Xijie  CHEN Guangqian 《海洋学报(英文版)》2009,28(1):37-46

Samples of sediments and the overlying water were collected in the Qi'ao Island coastal zone, the Zhujiang (Pearl River) Estuary (ZE). Denitrification rates, sediment oxygen demand (SOD) , and fluxes of inorganic nitrogen compounds were investigated with N2 flux method, using a self-designed continuous flow through and auto-sampling system. The results indicate that the denitrification rates varied between 222 and 908 μmol/(m2·h) with an average of 499 μmol/(m2·h). During incubation, the sediments absorbed dissolved oxygen in the overlying water with SOD ranging from 300 to 2 363 μmol/(m2·h). The denitrification rates were highly correlated with the SOD (r2 =0.77) regardless of the NO3- + NO2- concentrations in the overlying water, organ- ic carbon contents in sediments and water temperature, suggesting that the SOD was probably the main environ-mental factor controlling the denitrification in the Qi'ao Island coastal zone. There was a net flux of NO3- + NO2-into the sediments from the overlying water. The NH4+ flux from sediments into water as the result of mineraliza-tion was between 12. 3 and 210. 3 μmol/(m2·h) ,which seems limited by both organic carbon content in sedi-ment and dissolved oxygen concentration in the overlying water.  相似文献   

涠洲岛潮滩表层沉积物中重金属的空间分布及其环境质量评价   总被引：2，自引：0，他引：2  

唐璐璐  陈志华  印萍  张军强 《海洋湖沼通报》2009,(2)

根据2006年4月对涠洲岛潮滩表层沉积物的调查资料,分析了表层沉积物中重金属元素Hg、Cu、Pb、Zn、Cd、Cr、As的含量水平及空间分布特征,运用单因子评价法对其环境质量进行了评估,并通过相关性分析、因子分析探讨了几种重金属元素的物源.结果表明:涠洲岛潮滩环境质量状况良好,各元素均未达到污染水平,多数地区存在Cu的玷污,个别地区存在As的玷污;各分析元素较多的累积在人为活动相对频繁的XKZ、W05断面附近区域;Hg、Cu、Zn、Cr显著正相关,以环境背景来源为主,Pb、As较多的受到人为因素的影响.  相似文献   

西南极纳尔逊岛Stansbury半岛火山岩地质特征初论          下载免费PDF全文

郑祥身 《极地研究》1990,2(4):28-35

纳尔逊岛Stansbury半岛被玄武质、玄武安山质熔岩和火山碎屑岩以及沉积火山碎屑岩所覆盖。区域火山岩地层对比证明其是在形成长城站地区火山岩的同一火山作用下发育起来的。据地质接触关系和岩石组合特点,初步认为该半岛火山岩地层可以进一步划分为三个岩性段,分别形成于两期火山作用。该半岛的主要构造线方向平行于菲尔德斯海峡,这在地貌特征及次火山岩的分布上得到了证实。  相似文献   

Characteristics of bottom dissolved oxygen in Long Island Sound,New York     

Younjoo J. Lee  Kamazima M.M. Lwiza 《Estuarine, Coastal and Shelf Science》2008

The variability of bottom dissolved oxygen (DO) in Long Island Sound, New York, is examined using water quality monitoring data collected by the Connecticut Department of Environmental Protection from 1995 to 2004. Self-organizing map analysis indicates that hypoxia always occurs in the Narrows during summer and less frequently in the Western and the Central Basins. The primary factor controlling the bottom DO, changes spatially and temporally. For non-summer seasons, the levels of bottom DO are strongly associated with water temperature, which means DO availability is primarily driven by solubility. During summer, stratification intensifies under weak wind conditions and bottom DO starts to decrease and deviate from the saturation level except for stations in the Eastern Basin. For the westernmost and shallow (<15 m) stations, bottom DO is correlated with the density stratification (represented by difference between surface and bottom density). In contrast, at deep stations (>20 m), the relationship between oxygen depletion and stratification is not significant. For stations located west of the Central Basin, bottom DO continues to decrease during summer until it reaches its minimum when bottom temperature is around 19–20 °C. In most cases the recovery to saturation levels at the beginning of fall is fast, but not necessarily associated with increased wind mixing. Therefore, we propose that the DO recovery may be a manifestation of either the reduced microbial activity combined with the depletion of organic matter or horizontal exchange. Hypoxic volume is weakly correlated to the summer wind speed, spring total nitrogen, spring chlorophyll a, and maximum river discharge. When all variables are combined in a multiple regression, the coefficient of determination (r²) is 0.92. Surprisingly, the weakest variable is the total nitrogen, because when it is excluded the coefficient r² only drops to 0.84. Spring bloom seems to be an important source of organic carbon pool and biological uptake of oxygen plays a more crucial role in the seasonal evolution of bottom DO than previously thought. Our results indicate that the reassessment phase of the Long Island Sound Total Maximum Daily Load policy on nitrogen loading will most likely fail, because it ignores the contributions of the spring organic carbon pool and river discharge. Also, it is questionable whether the goal of 58.5% anthropogenic nitrogen load reduction is enough.  相似文献   

Factors controlling dissolved silica in coral reef surface water of Urasoko Bay, Ishigaki Island, Japan     

Kazuo Abe 《Journal of Oceanography》2008,64(6):961-967

From August 2006 to August 2007, the concentrations of dissolved silica (Si(OH)₄) were monitored in the surface water of Urasoko Bay and the mouth of the stream that runs into the bay. Urasoko Bay is located on the northern coast of Ishigaki Island, Okinawa, Japan, which is in a subtropical area of the North Pacific Ocean and is surrounded by a relatively poorly developed fringing reef. Added to these samples were freshwater from the upstream area and brackish water that exudes at the beach site, which were collected from April to June 2007. Rainwater samples were also collected during the study period. The concentration of Si(OH)₄ generally decreased from upstream to the bay site, and, on clear days, Si(OH)₄ data from all study sites (the bay, beach, stream mouth, and upstream) plotted against salinity fell on a single straight line. When the influence of rainwater was, the results were scattered below the straight line, which suggests dilution by rainwater with a much lower Si(OH)₄ concentration. These findings show that offshore seawater, rainwater, and upstream freshwater regulate the concentration of Si(OH)₄ in the surface water of Urasoko Bay.  相似文献   

Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)     

Ursula Werner  Anna Blazejak  Paul Bird  Gabriele Eickert  Raphaela Schoon  Raeid M.M. Abed  Andrew Bissett  Dirk de Beer   《Estuarine, Coastal and Shelf Science》2008,76(4):876-888

We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 μm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O₂ m⁻² h⁻¹ and was strongly correlated with Chl a content, which lay between 31 and 84 mg m⁻². An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2–1.0 mmol Ca²⁺ m⁻² h⁻¹). The sediments of at least three stations were net calcifying. Sedimentary N₂-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N₂ m⁻² h⁻¹ and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N₂-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.  相似文献   

Investigating internal waves east of the Hainan Island using optical satellite remote sensing data   总被引：1，自引：1，他引：0  

杨顶田 《热带海洋学报》2009,28(5):29-34

Marginal water of east Hainan Island was an area that internal waves occurred frequently, however, few studies was found and mechanism for internal waves formation was unclear. In the paper, China Brazil earth Resources Satellite data (CBERS) was used to detect and calculate distribution, direction, wavelength and amplitude of internal waves in marginal water of east Hainan Island and the mechanism of internal waves formation was also analyzed, results showed that direction of internal wave was off shoreward and wavelength was about 150-200m . The mechanism for internal wave’s formation can be postulated as by upwelling or tide tracing back.  相似文献