矢量波场弹性波Kirchhoff偏移

Based on Kuo and Dai＇s vectorial wave-field extrapolation equations, we derive new Kirchhoff migration equations by introducing unit vectors which represent the ray directions at the imaging points of the reflected P- and PS converted-waves. Furthermore, using the slope of the events on shot records and a ray racing procedure, mirror-image reflection points are found and the reflection data are smeared along the Fresnel zone. The migration method proposed in this paper solves two troublesome imaging problems caused by limited receiving aperture and migration artifacts resulting from wave propagation at the velocities of non original wave type. The migration method is applied successfully with model data, demonstrating that the new method is effective and correct.     

Does canopy wetness matter? Evapotranspiration from a subtropical montane cloud forest in Taiwan

Evapotranspiration (ET) and canopy wetness were measured over a 2‐year intensive field campaign at the Chi‐Lan Mountain cloud forest site in Taiwan. Eddy covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress (Chamaecyparis obtusa var. formosana). ET was 553 mm yr^?1 over the study period with an annual rainfall and fog deposition of 4893 and 288 mm yr^–1, respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon), and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet‐enhanced/dry‐reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning, and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1–3 h, and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6 mm s^–1) as compared with 7.6 mm s^?1 in the dry days. Consequently, the dry‐reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist‐adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog‐free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. Copyright © 2012 John Wiley & Sons, Ltd.     

Modeling of non‐point source nitrogen pollution from 1979 to 2008 in Jiaodong Peninsula,China

Efforts to reduce land‐based non‐point source (NPS) pollutions from watersheds to coastal waters are ongoing all around the world. In this study, annual yield of NPS nitrogen (NPS‐N) pollution in Jiaodong Peninsula, China from 1979 to 2008 was estimated. The results showed that: from 1979 to 2008, NPS‐N yields exhibited significant inter‐annual variations and an increasing trend on decadal scale. High NPS‐N yield was mainly found in east and south parts, as well as the urbanized coastal regions in Jiaodong Peninsula. Among the 32 river basins, the three largest basins yielded more than 41.16% of the NPS‐N. However, some small coastal watersheds along the South Yellow Sea and Jiaozhou Bay had higher per unit area yield. Most of the small watersheds characterized by seasonal runoff had coastal waters pertain to mild and moderate pollution levels. The ratio of watershed area to shoreline length and the up‐stream land use had significant impacts on NPS‐N flux through the shoreline. Among the four adjacent coastal areas of Jiaodong Peninsula, Jiaozhou Bay was the most noteworthy one not only because of high levels of land‐based NPS‐N pollution but also because of its nearly enclosed structure. The combination between integrated coastal zone management and integrated river basin management, land use planning and landscape designing in Jiaodong Peninsula is recommended. Copyright © 2013 John Wiley & Sons, Ltd.     

Emission of phosphine in intertidal marshes of the Yangtze Estuary

Emission of phosphine, a gaseous form of P, is presently considered a potential pathway of the P biogeochemical cycle in aquatic sediments. This study investigated the emission fluxes of phosphine and its potential production mechanisms in the intertidal marshes of the Yangtze Estuary. It is shown that the relatively high emission fluxes of phosphine were measured in warm seasons, with the values of 3.85–24.9 ng m^?2 h^?1 and 4.21–36.5 ng m^?2 h^?1 in August and September, respectively. In contrast, lower fluxes of phosphine appeared in May (1.23–6.32 ng m^?2 h^?1) and January (0.21–0.91 ng m^?2 h^?1). Also, the fluxes of phosphine were generally higher in the freshwater marsh, compared with the brackish marsh. The spatio-temporal pattern of phosphine emissions was observed to be mainly associated with sediment structure, temperature and salinity. Meanwhile, the significant correlations of phosphine emissions with sedimentary P and alkaline phosphatase activities reflect that phosphine probably derives from the microbial transformations of PO₄ and organic P. In addition, it is estimated that approximately 1.08 × 10⁶ g of phosphine is released annually from sediments into the pelagic water of the Yangtze Estuary. Therefore, it is concluded that phosphine emissions may be an important internal source of P, making a significant contribution to the occurrence of algal blooms especially during warm seasons.     

靖边气田北部中奥陶统马家沟组五_4~1储层沉积微相组合与储层非均质性控制因素

中奥陶统马家沟组上部马五41储层是鄂尔多斯盆地靖边气田主力产气段,根据该层段的岩石学特征和沉积构造等,可划分为3个亚相以及9个微相组合。该储层的储集性能具有强烈的非均质性,微观上表现为低孔低渗,以微细喉、细喉为主;纵向上表现为反韵律、随机韵律、均质韵律3种韵律模式,平面上表现为平均岩心孔隙度、渗透率分布的非均一性。沉积微相及微相组合差异性是控制岩石孔隙发育的基础,成岩作用决定了孔隙发育的程度,古岩溶地貌类型对储层分布有着明显制约作用,最终导致该区储集性能在纵横向上的非均质性。     

http://www.sciencedirect.com/science/article/pii/S1674987111001344

The Rehai Geothermal Field,located in Tengcbong County,in central-western Yunnan Province, is the largest and most intensively studied geothermal held in China.A wide physicochemical diversity of springs(ambient to ~97℃;pH from≤.8 to≥9.3) provides a multitude of niches for extremophilic microorganisms.A variety of studies have focused on the cultivation,identification,basic physiology,taxonomy,and biotechnological potential of thermophilic microorganisms from Rehai.Thermophilic bacteria isolated from Rehai belong to the phyla Firmicutes and Deinococcus-Thenmts. Firmicutes include neutrophilic or alkaliphilic Anoxybacillus,Bacillus,Caldalkalibacillus.Caldanaerobacier, Laceyella,and Geobacillus,as well as thermoacidophilic Alicyclobacillus and Sulfobacillus. Isolates from the Deinococcus-Thermus phylum include several Meiothermus and Thennus species.Many of these bacteria synthesize thermostable polymer-degrading enzymes that may be useful for biotechnology. The thermoacidophilic archaea Acidianus.Melal/osp/utera.and Suljolobus have also been isolated and studied.A few studies have reported the isolation of thermophilic viruses belonging to Siphoviridae(TTSP4 and TTSPIO) and Fuselloviridae(STSVl) infecting Thennus spp.and Suljolobus spp..respectively.More recently,cultivation-independent studies using 16S rRNA gene sequences, shotgun metagenomics,or "functional gene" sequences have revealed a much broader diversity of microorganisms than represented in culture.Studies of the gene and mRNA encoding the large subunit of the ammonia monooxygenase(imioA) of ammonia-oxidizing Archaea(AOA) and the tetraether lipid erenarchaeol. a potential biomarker for AOA.suggest a wide diversity,but possibly low abundance,of thermophilic AOA in Rehai.Finally,we introduce the Tengchong Partnerships in International Research and Education(PIRE) project,an international collaboration between Chinese and U.S.scientists with the goal of promoting international and interdisciplinary cooperation to gain a more holistic and global view of life in terrestrial geothermal springs.     

http://www.sciencedirect.com/science/article/pii/S1674987111001319

The microbial diversity in Wuli Area,Qinghai-Tibetan Plateau was investigated using 16S rRNA gene phylogenetic analyses.A total of 117 bacterial and 66 archaeal 16S rRNA gene clones were obtained from the Wuli cold springs.The bacterial clones could be classified into Pwteobacteria,Acidobacteria, Deinococci,Sphingobacteria,Flavobacteria.Nitrospirae,Actinobacteria,Gemmatimonadetes, and unclassified-bacteria;and the archaeal clones could be classified into Crenarchaeota and Thaumarchaeota.Among the major groups,Pwteobacteria and Crenarchaeota were dominant in the bacterial and archaeal 16S rRNA gene clone libraries,respectively.The clone sequences obtained in Wuli cold springs were closely related to those from cold habitats,such as snow/ice/soils on high mountains or at high latitude.Especially,the microbial community composition of Wuli Area was more similar to that in Tibetan glaciers than cold environments of other locations.The data presented in this study have implications for a better understanding of microbial diversity in cold springs on the Qinghai-Tibetan Plateau.     

http://www.sciencedirect.com/science/article/pii/S1674987111001022

This study proposes three models to explain the mechanism of the three major types of mafic dyke swarms.Parallel dyke swarms form in response to a regional stress field,e.g.the mafic dyke swarms in the...     

盐渍土地区岩土工程勘察中水土腐蚀性评价探讨——以渭北东部卤阳湖(卤泊滩)地区为例

卤阳湖(俗称卤泊滩)地处关中平原东部,东西长约30 km,南北宽1.5～7 km,总面积124 km2。卤阳湖土壤盐碱化严重,不宜农作物生长,对其开发中遇到的主要问题是盐渍土勘察、腐蚀性评价和地基处理。卤泊滩地基土属于硫酸盐渍土。     

鄱阳湖流域水化学特征及影响因素分析

在地球表生系统中,化学风化作用强烈改变着岩石、水体、土壤和大气成分,是元素地球化学循环的最主要驱动力。河水溶解物质主要来源于流域内岩石化学风化,同时受到降水、人类活动的影响。文中通过对鄱阳湖流域河水样品的采集和化学成分分析,结合流域地质背景,研究了河水化学成分特征及其影响因素。结果显示,与20世纪80年代相比,本区河水Cl-、SO24-所占比例显著增高,有逐渐酸化趋势;与世界上其他主要河流相比较,该区Ca2+/Na+、Mg2+/Na+、HCO3-/Na+等比值偏低,反映了较强的蒸发岩溶解及人类活动影响特征。该区河水离子特征主要由岩石风化所控制,降水对该区河水溶解物质贡献率为10.3%,农业生产活动对鄱阳湖水溶解物质贡献率为4.9%,矿山活动对饶河丰水期、枯水期离子总量贡献率分别为8.9%、14.6%。