The Impact of Hurricane Katrina on the Coastal Vegetation of the Weeks Bay Reserve,Alabama from NDVI Data

Normalized Difference Vegetation Index (NDVI) data were used to investigate vegetation changes after Hurricane Katrina (2005) for the Weeks Bay Reserve and surrounding area of coastal AL. Landsat 5 satellite images were acquired before landfall (March 24, 2005), after landfall (September 16, 2005), and 8 months after landfall (April 28, 2006). The March 2005 to September 2005 image comparison showed that average NDVI values decreased by 49% after landfall. Continuing into the next year, average NDVI values were −44% lower in April 2006 than they were in March 2005. Among habitat types, the estuarine emergent wetland experienced the largest average NDVI value decrease (−64%). The estuarine emergent wetland NDVI values continued to decrease by −27% from September 2005 to April 2006, whereas other habitats increased in NDVI. This continued suppression of NDVI values was attributed to increased salinity from the storm surge and to regional drought conditions that occurred after landfall. These results provide insight into the sensitivity of coastal vegetation from the interactions of both tropical cyclones and long-term environmental conditions.     

塔北地区变形样式及其分布规律

塔北地区包括库车前陆盆地和塔北前陆克拉通地区两大变形带，在库车前陆盆地，垂向上，主要受滑脱层发育及其展布、构造地层组合及岩层埋深等因素控制，深层一般为被动顶板双冲构造及断变褶皱，中层三角带、冲起构造，浅层为断展，滑脱及底辟褶皱；横向上，与挤压应力大小、地层岩石力学性质、滑脱层发育程度等相关，自造山带前缘向前陆克拉通方向，褶皱一般由紧闭，不对称或倒转变为平缓，开阔，并由断变，断展褶皱变为滑脱褶皱；变     

Characterization of phosphoric acid- and lime-stabilized tropical lateritic clay

The effect of calcium-based stabilizers such as lime on the geotechnical properties of tropical soils has been reported by many researchers. However, the amount of literature available on the micro-structural, molecular, and leaching characteristics of lime and in particular phosphoric acid-stabilized lateritic clays has been limited. This research was carried out in an attempt to identify the time-dependent soil-chemical reactions. In addition, the possible mechanisms that contributed to the stabilization process were discussed in the light of various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry (EDAX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR) etc. Based on the results it was found that in lime-treated samples, the coating action of free iron oxides on clay particles imposed inhibitive effects on the dissolution of clay alumina. On the other hand, in phosphoric acid-stabilized soil, due to the increase in solubility of metal oxides and also the subsequent release of clay alumina the formation of cementitious compounds were more feasible. From engineering point of view, the phosphoric acid-stabilized lateritic soil showed the highest degree of improvement with an approximately threefold strength increase in comparison with the natural soil over an 8-month curing period.     

Spatial pattern of Karst rock desertification in the Middle of Guizhou Province,Southwestern China

Karst rocky desertification is a typical type of land degradation in the Southwestern China. It has great ecological and economical implications for the local people. Landsat images from the middle of Guizhou Province collected in 1974, 1993 and 2001 were used for change detection of the pattern of Karst rocky desertification. The results show the following findings: (1) Desertification area expanded drastically in 27 years, at an increasing rate about 116.2 km²/year. (2) High areas (900–1,500 m) are the most affected. (3) Areas with the slope <5° or >25° are also easily tend to be Karst rocky deserted. (4) The process of Karst rocky desertification is nearly irreversible. Few areas of Karst rocky desertification could be meliorated to non-desertification land. (5) Most of the degraded lands are located in the south and the central of the study region, and the meliorated land areas are sparsely located in the east and the west part of the region. All these findings would provide bases for the decision-making of the local government to improve the Karst rocky desertification     

河流深槽沉积体与油气的关系——以辽河坳陷大25井区为例

河流深槽沉积体是河流沉积的一种特殊沉积体。辽河坳陷第三纪断裂活动强烈，火山岩广泛分布，形成了独特的地貌条件，具备形成河流深槽沉积体的地质条件。本文以辽河坳陷东部凹陷大２５井区为例，对河流深槽沉积体的成因及特征进行探讨，证实了大２５井区巨厚砂砾岩沉积是河流在火山岩古地形的限制下发生急转弯，在其变曲河段的深槽中沉积的深槽沉积体。该沉积体中发育良好的储集空间，有利于油气储集。该类储集体的发现，丰富了辽河坳陷的储层类型，为油气勘探提供了新的领域。     

拉尔玛金矿的生物成矿作用

位于甘、川两省交界处的拉尔玛金矿床,赋存于下寒武统太阳顶群,矿区内岩浆活动不强烈,矿床中断裂构造较发育,矿石矿物种类较齐全。矿石中的生物有机地球化学特征表明其为细菌和低等藻类生物体衍生的生物标志物和遗传特征,证明了太阳顶群中的有机质起源于菌藻类生物。矿石中的金属矿物生物组构有生物有机胶体组构和矿交代生物组构,说明生物成矿作用经历了直接成矿和间接成矿,即两轮聚矿作用,菌藻生物的第一轮聚金主要形成矿源层,生物的两轮聚金结果,形成此矿床。     

Linking the northern hemisphere sea-ice reduction trend and the quasi-decadal arctic sea-ice oscillation

The nature of the reduction trend and quasi-decadal oscillation in Northern Hemisphere sea-ice extent is investigated. The trend and oscillation that seem to be two separate phenomena have been found in data. This study examines a hypothesis that the Arctic sea-ice reduction trend in the last three decades amplified the quasi-decadal Arctic sea-ice oscillation (ASIO) due to a positive ice/ocean-albedo feedback, based on data analysis and a conceptual model proposed by Ikeda et al. The theoretical, conceptual model predicts that the quasi-decadal oscillation is amplified by the thinning sea-ice, leading to the ASIO, which is driven by the strong positive feedback between the atmosphere and ice-ocean systems. Such oscillation is predicted to be out-of-phase between the Arctic Basin and the Nordic Seas with a phase difference of 3/4, with the Nordic Seas leading the Arctic. The wavelet analysis of the sea ice data reveals that the quasi-decadal ASIO occurred actively since the 1970s following the trend starting in the 1960s (i.e., as sea-ice became thinner and thinner), as the atmosphere experienced quasi-decadal oscillations during the last century. The wavelet analysis also confirms the prediction of such out-of-phase feature between these two basins, which varied from 0.62 in 1960 to 0.25 in 1995. Furthermore, a coupled ice-ocean general circulation model (GCM) was used to simulate two scenarios, one without the greenhouse gas warming and the other having realistic atmospheric forcing along with the warming that leads to sea-ice reduction trend. The quasi-decadal ASIO is excited in the latter case compared to the no-warming case. The wavelet analyses of the simulated ice volume were also conducted to derive decadal ASIO and similar phase relationship between the Arctic Ocean and the Nordic Seas. An independent data source was used to confirm such decadal oscillation in the upper layer (or freshwater) thickness, which is consistent with the model simulation. A modified feedback loop for the sea-ice trend and ASIO was proposed based on the previous one by Mysak and Venegas and the ice/albedo and cloud/albedo feedabcks, which are responsible for the sea ice reduction trend.     

Distribution and abundance of thaliaceans in the northwest continental shelf of South China Sea, with response to environmental factors driven by monsoon

The distribution and abundance of thaliaceans were studied in relation to physical and biological variables during summer and winter in the northwest continental shelf of South China Sea. Based on the topography and water mass of the surveyed region, it was divided into three subregions: region I (onshore waters of the east Leizhou Peninsula), region II (onshore waters of the east and southeast Hainan Island) and region III (offshore waters from Leizhou Peninsula to Hainan Island). During summer due to a strong southwest monsoon, a cold eddy and coastal upwelling dominated in regions I and II, respectively, whereas the onshore and offshore waters were vertically mixed during winter due to a strong northeast monsoon. A total of 18 thaliacean species (including 3 subspecies) were collected. The mean species richness was higher in summer compared to winter, with the occurrence of higher values during summer and winter at region II and region III, respectively. The average thaliacean abundance is also higher in summer than in winter, with higher values at region I in summer and no significant difference among three subregions in winter. Doliolum denticulatum and Thalia democratica were the dominant species during summer and winter. The results suggested that the seasonal and spatial distribution of thaliacean richness was considered to be the result of physical factors such as temperature and ocean current in summer and winter. Spatial distribution of thaliacean abundance was affected by chlorophyll a concentration increased by the occurrence of coastal upwelling and cold eddy in summer. Southwest and northeast monsoons are shown to play an important role in shaping the distribution of species richness and abundance of thaliaceans in the northwest continental shelf of South China Sea.     

光栅Bragg地震检波器的传感特性研究(英文)

针对目前石油地震勘探的瓶颈—检波器性能差的问题,设计了一种新型光纤Bragg光栅（FBG）地震检波器,阐述了其工作原理,并从理论上给出了检波器的响应函数等参数。由于FBG的传感优势,这种新型地震检波器动态范围可达94dB,灵敏度高,重量轻,造价低,是理想的新一代地震勘探信号采集单元。