The influence of increased iron concentration on survival and growth of seedlings and young plants of eelgrass Zostera marina          下载免费PDF全文

Xi‐Tao Wang  Qian Zhang  Yan‐Shan Liu  Pei‐Dong Zhang  Wen‐Tao Li 《Marine Ecology》2017,38(3)

Iron (Fe) is an essential nutrient for plants but toxic at high concentrations. We subjected seedlings and young plants of eelgrass Zostera marina to different seawater iron concentrations (500, 600, 700, 800, 1,000 and 1,500 μg/L) for 30 days under controlled laboratory conditions. Natural seawater without added iron (500 μg/L) was used as reference seawater. No sediments were provided to avoid iron scavenging by particle surfaces in the sediment. We measured plant response in terms of survivorship, morphology, growth rate and productivity. Survival analysis combined with morphological, dynamic and productive assessment suggested that the optimum seawater iron concentration for the establishment of Z. marina seedlings and young plants is 700 μg/L. The no observed effect concentration, lowest observed effect concentration, lethal concentration that caused an increase in mortality to 10% of that of the control, and the effect concentration that caused a decrease in growth to 10% of that of the control values of young plants were significantly lower than those of seedlings, implying an increased sensitivity to high Fe concentrations (>1,000 μg/L). This study further develops our understanding of the physiological ecology of the early life stages of Z. marina and provides data that could prove helpful in the development of successful eelgrass restoration and conservation.  相似文献   

琼东南盆地北礁地区梅山组丘形反射特征     

李俞锋  蒲仁海  胡宝清  樊笑微  李斌  邓东  王飞  郭瑞川 《海洋学报》2017,39(12):53-62

目前琼东南盆地北礁凹陷中中新统梅山组顶部丘形反射引起广泛关注,但对其成因有不同认识。本文通过高精度二维、三维地震、钻井资料,研究丘形反射的特征。研究表明北礁地区梅山组顶部发育近东西向展布的长条形丘体,丘间为水道,丘内为中-弱振幅的地震反射,与西南部强振幅水道砂岩形成鲜明的对比,波阻抗反演揭示丘内为低波阻抗,属泥岩范畴。梅山组塑性丘内地层发生重力扩展,在其上覆的脆性地层（强振幅砂岩和弱振幅泥岩）发育多边形断层,反推出梅山组形成于深水环境,丘为泥丘,沉积环境分析也认为北礁凹陷中中新世为半深海沉积,梅山组的丘-谷分别对应上覆地层的谷-丘,认为是底流剥蚀/沉积成因。本文的研究对南海北部丘形反射的认识有重要意义,并可降低油气探勘风险。  相似文献   

Expected Sliding Distance of Vertical Slit Caisson Breakwater     

Dong Hyawn KIM 《海洋工程》2017,31(3):317-321

Evaluating the expected sliding distance of a vertical slit caisson breakwater is proposed. Time history for the wave load to a vertical slit caisson is made. It consists of two impulsive wave pressures followed by a smooth sinusoidal pressure. In the numerical analysis, the sliding distance for an attack of single wave was shown and the expected sliding distance during 50 years was also presented. Those results were compared with a vertical front caisson breakwater without slit. It was concluded that the sliding distance of a vertical slit caisson may be over-estimated if the wave pressure on the caisson is evaluated without considering vertical slit.  相似文献   

Succession and seasonal variation in epilithic biofilms on artificial reefs in culture waters of the sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis>     

刘立明  杜荣斌  张晓凌  董双林  孙世春 《中国海洋湖沼学报》2017,35(1):132-152

Periphytic biofilms in aquaculture waters are thought to improve water quality, provide an additional food source, and improve the survival and growth of some reared animals. In the Asia- Pacific region, particularly in China, artificial reefs are commonly used in the commercial farming of sea cucumbers. However, few studies have examined the epilithic biofilms on the artificial reefs. To gain a better understanding of the succession of epilithic biofilms and their ecological processes in sea cucumber culture waters, two experiments were conducted in culture waters of the sea cucumber Apostichopus japonicus in Rongcheng, China, using artificial test panels. On the test panels of succession experiment, more than 67 species were identified in the biofilms. On the test panels of seasonal variation experiment, more than 46 species were recorded in the biofilms. In both experiments, communities of epilithic biofilms were dominated by diatoms, green algae and the annelid Spirorbis sp. In the initial colonization, the dominant diatoms were Cocconeis sp., Amphora spp. and Nitzschia closterium in June, which were succeeded by species of Navicula, Cocconeis and Nitzschia (July to September), and then by Licmophora abbreviata, Nitzschia closterium and Synedra spp. in the following months. A diatom bloom in the autumn and filamentous green algae burst in the summer were also observed. Ecological indices well annotated the succession and seasonal changes in epilithic communities. Multidimensional scaling (MDS) analysis found significant differences in diatom community composition among months and seasons. Fast growth of biofilms was observed in the summer and autumn, whereas the biomass of summer biofilms was largely made up of filamentous green algae. Present results show that the components of epilithic biofilms are mostly optimal foods of A. japonicus, suggesting that biofilms on artificial reefs may contribute important nutritional sources for sea cucumbers during their growth seasons. Future works should include quantitative determination of the contribution of epilithic biofilms to the diet of A. japonicus, potential roles of epilithic biofilms in regulating the water quality of sea cucumber ponds, and the regulation of epilithic biofilms in sea cucumber culture ponds.  相似文献   

农牧交错带农田土壤风蚀PM10释放特征     

南岭  董治宝  肖锋军 《中国沙漠》2017,37(6):1079-1084

粉尘释放是风蚀造成危害的一个重要过程。以农牧交错带沙区和非沙区农田土壤为研究对象,利用室内风洞模拟实验,实时监测了风蚀过程中释放的PM₁₀,分析了PM₁₀的动态变化特征,以深入认识土壤风蚀粉尘释放机理。结果表明：非沙区农田土壤风蚀强度远低于沙区农田,与风速呈指数函数关系;非沙区农田的土壤粉尘释放在不同风速下均以气流直接抬升模式为主,平均PM₁₀通量与风速呈线性函数关系,最大PM₁₀通量与风速呈幂函数关系;沙区农田的土壤粉尘释放在风速增大到一定程度后呈气流直接抬升和砂粒跃移冲击复合模式,最大PM₁₀通量增加不明显,但平均PM₁₀通量明显高于非沙区农田;对于沙区和非沙区农田而言,平均PM₁₀通量与风蚀速率呈对数函数关系。  相似文献   

Design and performance of a novel multi-function debris flow mitigation system in Wenjia Gully,Sichuan     

F.Z. Liu  Q. Xu  X.J. Dong  B. Yu  J.D. Frost  H.J. Li 《Landslides》2017,14(6):2089-2104

The post-earthquake debris flows in the Wenjia Gully led to the exposure of the shortcomings in the design of the original conventional debris flow mitigation system. A predicament for the Wenjia mitigation system is a large amount of loose material (est. 50 × 10⁶ m³) that has been deposited in the gully by the co-seismic landslide, providing abundant source material for debris flows under saturation. A novel design solution for the replacement mitigation system was proposed and constructed, and has exhibited excellent performance and resilience in subsequent debris flows. The design was governed by the three-phase philosophy of controlling water, sediment, and erosion. An Early Warning System (EWS) for debris flow that uses real-time field data was developed; it issues alerts based on the probabilistic and empirical correlations between rainfall and debris flows. This two-fold solution reduces energy of the debris flow by combining different mitigation measures while minimizing the impact through event forecasting and rapid public information sharing. Declines in the number and size of debris flows in the gully, with increased corresponding rainfall thresholds and mean rainfall intensity-duration (I-D) thresholds, indicate the high efficacy of the new mitigation system and a lowered debris flow susceptibility. This paper reports the design of the mitigation system and analyzes the characteristics of rainfall and debris flow events that occurred before and after implementation of the system; it evaluates the effectiveness of one of the most advanced debris flow mitigation systems in China.  相似文献   

The δ18O of UST Quartz in Two Porphyry Deposits,China          下载免费PDF全文

Huanchun Qu  Maoyu Sun  Pu Dong 《Resource Geology》2017,67(1):109-115

The unidirectional solidification textures (UST) quartz is generally thought to form from fluids exsolved from shallow intrusions and/or magma chambers, but such an idea is still poorly constrained from the evidence of stable isotopes. In this study, we report for the first time the δ¹⁸O of quartz that shows UST from the Qulong Cu–Mo and the Yechangping Mo porphyry deposits in China. The analysis results show that the UST quartz samples from the Qulong deposit have δ¹⁸O values ranging from +6.2 ‰ to +7.6 ‰, which are similar to that of quartz phenocrysts (+6.7 ‰ to +7.8 ‰). In contrast, the UST quartz samples from the Yechangping porphyry Mo deposit yield a high δ¹⁸O value (+10.0 ‰). The δ¹⁸O_water value of Yechangping UST quartz (+8.5 ‰) is also higher than that of Qulong (+4.6 ‰ to +5.8 ‰). Hydrothermal biotite from potassic alteration and sericite from early phyllic alteration at Qulong have similar δ¹⁸O values to UST quartz, suggesting the involvement of magmatic fluids during this stage of deposit evolution.  相似文献   

Evaluation of CBM reservoir fracture characteristics by azimuthal AVA inversion     

Yiming Zhuang  Shouhua Dong  Haibo Wu  Yaping Huang 《Arabian Journal of Geosciences》2017,10(3):66

Exploitation of coalbed methane (CBM) is directly affected by the strike and density of fractures, particularly because fractures can act as conduits for water and gas (after desorption). To realize the azimuthal amplitude versus angle (AVA) inversion for a CBM reservoir, we treated reservoirs whose fractures are aligned vertically as being equivalent to a horizontal transverse isotropic medium and simplified the P-P wave reflection coefficient formula to an approximately linear equation. Then, we adopted a modified damping least squares algorithm to solve the azimuthal AVA inversion problem. With edited macro-bins, corrected residual moveout, and normalized amplitude, the azimuthal gathers exhibited unambiguous azimuthal AVA characteristics. The #3 CBM reservoir in the Qinshui Basin was selected for a case study. The density and strike of the reservoir fractures were obtained and analyzed, and the reservoir was divided into three classes according to fracture density. Finally, in comparison with the gas production data, we confirmed that the inversion results and reservoir classification were both reasonable and credible.  相似文献   

The potential hydrothermal systems unexplored in the Southwest Indian Ocean   总被引：1，自引：0，他引：1  

Yanhui Suo  Sanzhong Li  Xiyao Li  Zhen Zhang  Dong Ding 《Marine Geophysical Researches》2017,38(1-2):61-70

Deep-sea hydrothermal vents possess complex ecosystems and abundant metallic mineral deposits valuable to human being. On-axial vents along tectonic plate boundaries have achieved prominent results and obtained huge resources, while nearly 90% of the global mid-ocean ridge and the majority of the off-axial vents buried by thick oceanic sediments within plates remain as relatively undiscovered domains. Based on previous detailed investigations, hydrothermal vents have been mapped along five sections along the Southwest Indian Ridge (SWIR) with different bathymetry, spreading rates, and gravity features, two at the western end (10°–16°E Section B and 16°–25°E Section C) and three at the eastern end (49°–52°E Section D, 52°–61°E Section E and 61°–70°E Section F). Hydrothermal vents along the Sections B, C, E and F with thin oceanic crust are hosted by ultramafic rocks under tectonic-controlled magmatic-starved settings, and hydrothermal vents along the Section D are associated with exceed magmatism. Limited coverage of investigations is provided along the 35°–47°E SWIR (between Marion and Indomed fracture zones) and a lot of research has been done around the Bouvet Island, while no hydrothermal vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of hydrothermal systems along these two sections. An off-axial hydrothermal system in the southern flank of the SWIR that exhibits ultra-thin oceanic crust associated with an oceanic continental transition is postulated to exist along the 100-Ma slow-spreading isochron in the Enderby Basin. A discrete, denser enriched or less depleted mantle beneath the Antarctic Plate is an alternative explanation for the large scale thin oceanic crust concentrated on the southern flank of the SWIR.  相似文献   

国内互联网地图POI存在的涉密问题及其解决办法     

左栋  张雨心 《测绘通报》2016,(9):108-111

随着基于互联网及各类导航设备的电子地图和地理信息服务的迅速发展,互联网地图上涉及国家安全保密信息的泄露和传播问题日益凸显,严重损害了国家利益,威胁着国家安全。承载这些涉密信息的最重要的载体便是POI。本文对我国互联网地图POI存在的涉密问题及其产生原因进行了分析,并从行政管理和软件技术两个方面提出了互联网地图POI涉密问题的解决办法,使互联网地图在更好地服务于社会公众的同时,确保国家主权与安全不受侵犯与威胁。  相似文献