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61.
Accurate rainfall distribution is difficult to acquire based on limited meteorological stations, especially in remote areas like high mountains and deserts. The Hexi Corridor and its adjacent regions (including the Qilian Mountains and the Alxa Plateau) are typical districts where there are only 30 available rain gauges. Tropical Rainfall Measuring Mission (TRMM) data provide a possible solution. After precision analysis of monthly 0.25 degree resolution TRMM 3B43 data from 1998 to 2012, we find that the correlations between TRMM 3B43 estimates and rain gauge precipitation are significant overall and in each station around the Hexi Corridor; however, the biases of annual precipitation differ in different stations and are seriously overestimated in most of the sites. Thus, Inverse Distance Weighting (IDW) interpolation method was used to rectify TRMM data based on the difference between TRMM 3B43 estimates and rain gauge observations. The results show that rectified TRMM data present more details than rain gauges in remote areas where there are few stations, alt- hough they show high coherence of distribution. Precipitation decreases from southeast to northwest on an annual and seasonal scale. There are three rainfall centers (〉500 mm) including Menyuan, Qilian and Toson Lake, and two low rain- fall centers (〈50 mm) including Dunhuang and Ejin Banner. Meanwhile, precipitation in most of the study area presents an increasing trend; especially in northern Qilian Mountains (〉5 mm/a), Badain Jaran Desert (〉2 mm/a), Toson Lake (〉20 mm/a) and Qingtu Lake (〉20 ram/a) which shows a significant increasing trend, while precipitation in Hala Lake (〈-2 mm/a) and Tengger Desert (〈-3 mm/a) demonstrates a decreasing trend.  相似文献   
62.
This paper continues the investigations of Clemens and Hartwig from 1992 on the proportion of garbage used as nesting material in the Kittiwake colony at Bulbjerg in the Jammerbugt in Northwest Denmark. Whereas in the year 1992 plastic garbage items were included in 39.3% of 466 Kittiwake nests in the Bulbjerg colony, in 2005 57.2% of 311 nests contained plastic debris. Although it has been forbidden to dispose of plastic garbage into the marine environment since the implementation of the MARPOL 73/78-Agreement/Annex V (Regulation for the Prevention of Pollution by Ship Waste) of 1989 and especially since the declaration of the North Sea as a MARPOL-Special Area for garbage in 1991, the pollution of the oceans and the North Sea is still an ubiquitous problem, particularly with regard to plastic waste. Plastic waste is presumably not used preferentially for nest-building, but in the context of available nesting material in the waters surrounding the breeding colony. Therefore the share of garbage parts in nests of certain species of birds is an indicator of the amount of waste in the natural environment in the vicinity of their breeding site.  相似文献   
63.
The Berre Lagoon has been under strong anthropogenic pressure since the early 1950s. The opening of the hydroelectric EDF power plant in 1966 led to large salinity drops. The zooplankton community was mainly composed of two common brackish species: Acartia tonsa and Brachionus plicatilis. Since 2006, European litigation has strongly constrained the input of freshwater, maintaining the salinity above 15. A study was performed between 2008 and 2010 to evaluate how these modifications have impacted the zooplankton community. Our results show that the community is more diverse and contains several coastal marine species (i.e., Centropages typicus, Paracalanus parvus and Acartia clausi). A. tonsa is still present but is less abundant, whereas B. plicatilis has completely disappeared. Strong predatory marine species, such as chaetognaths, the large conspicuous autochtonous jellyfish Aurelia aurita and the invasive ctenophore Mnemiopsis leidyi, are now very common as either seasonal or permanent features of the lagoon.  相似文献   
64.
lINTRoDUCTlONTheSouthernPiedmo12tph}siographicregioninthesoutheasternUnitedStatescoversaboutl6.5millionhae\tendingl2OOkmtYomsouthernVirginiatoeast-centralAlabamaandliesbetweentheAppalachianMountainsandthesouthernCoastalPlain(Carrekeretal.,l977).ThePiedmontslopessoutheast\\ardtbrapproximatel}25Oto3ookmtYom35omabovesealeveladjacenttothemountainsto]OOmabo\7esealevela1ongthesoLltheasternedge.Thislbothillsregionisdissectedbymanystreams.Thetopograph}isgentI}rolling,x`ithgentletomoderates…  相似文献   
65.
应力扰动影响地震的复发,并对了解地震周期和地震危险性具有重要的作用。加州帕克菲尔德圣安德烈斯断层上的大量重复地震为检查重复事件对中强地震发生的反应提供了难得的机会。使用高分辨率地震台网目录获得的187个M-0.4~1.7级地震重复序列,我们发现重复事件序列的复发时间到接近M4—5地震时缩短了,说明是由大地震触发的。该触发效应在5km左右的距离内最明显,相应的静态同震应力变化为0.6~26.6kPa,并随距离衰减。我们还发现从1993至1998年复发间隔相应地缩短了。这种几年经久不衰复发加速反映了1990年代初断层滑动加速并提高了加载速率。  相似文献   
66.
给出了一种短周期瑞雷(Rg)波的自动检测器,其目的是用于三分量台站所记录到的区域(<2.5°震中距)事件。该检测器以17~22s的瑞雷波自动检波方法为模型;我们已经修改了用在近距离和短周期的算法。我们对该检测器在印度中部一群定位很好的矿山爆破和该地区一组地面实测事件进行了检验。Rg波检测器结合了半自动的事件检测系统和定位算法,并被用在连续数据上。为进行前置滤波,对傅里叶方法和基于小波的方法进行了评估。在小波前置滤波后,我们看到了用Rg波检测器估算的后方位角标准偏差的样本,它与系列事件fk3CP波的后方位角相当。结果表明,用Rg震相后方位角定位与用小信噪比的初至震相后方位角定位这两种方法是兼容的。相对于傅里叶前置滤波而言,我们更推荐小波前置滤波,因为在近距离上,在低信噪比的背景上检波,小波前置滤波的一致性更好。  相似文献   
67.
1 Introduction Enantiornithines were the dominant birds nearly worldwide throughout the entire span of the Cretaceous (Chiappe, 1995; Feduccia, 1996). The adaptive radiation of opposite birds is little known besides the disparity of rostral morphology in Boluochia (Zhou, 1995), Longipteryx (Zhang et al., 2001), Longirostravis ( Hou et al., 2004), and the presence of stomach contents that reflect a diversity of diets. Like the structure of rostrum, differentiation of the locomotor apparatu…  相似文献   
68.
Authigenic gypsum crystals, along with pyrite and carbonate mineralization, predominantly calcites were noticed in distinct intervals in a 32 m long piston core, collected in the gas hydrate- bearing sediments in the northern portion of the Krishna-Godavari basin, eastern continental margin of India at a water depth of 1691 m. X-ray diffraction and energy dispersive spectrum studies confirm presence of pyrite, gypsum, calcite, and other mineral aggregates. The occurrence of gypsum in such deep sea environment is intriguing, because gypsum is a classical evaporite mineral and is under saturated with respect to sea water. Sedimentological, geochemical evidences point to diagenetic formation of the gypsum due to oxidation of sulphide minerals (i.e. pyrite). Euhedral, transparent gypsum crystals, with pyrite inclusions are cemented with authigenic carbonates, possibly indicating that they were formed authigenically in situ in the gas hydrate-influenced environment due to late burial diagenesis involving sulphate reduction and anaerobic oxidation of methane (AOM). Therefore, the authigenic gypsums found in sediments of the Krishna-Godavari and Mahanadi offshore regions could be seen as one of the parameters to imply the presence of high methane flux possibly from gas hydrate at depth.  相似文献   
69.
The role of endosymbiotic diatoms as pro-oxidant stressors in porifera has been investigated in the Antarctic sponge Haliclona dancoi in which the presence of diatoms is influenced by marked seasonal variations during the austral summer. Both chlorophaeopigments and frustules were absent in sponge tissues sampled in early November at the beginning of the summer and increased from the mid of December with slightly shifted temporal trends. The efficiency of antioxidant defenses in the sponge showed a marked response to symbionts with clearly enhanced values corresponding to the peak of diatoms.  相似文献   
70.
Andrew  M.  Gombos  William  G.  Powell  Ian  O.  Norton  万玲 《海洋地质》2009,(4):43-51
印度最大的油气聚集区位于西印度,具有独特的构造事件集中发生。中生代沿元古代活动带构造方向的裂谷作用形成了印度海岸的被动边缘盆地。Campanian期(83.5—70.6Ma),马达加斯加与印度发生分离,南北向正断层传播进入到Cambay Graben地区。在初始德干Reunion热点之上,晚Maastrichtian(70.6—65.5Ma)隆起在西北印度海岸产生了伸展应力场,形成盂买高断块。早古新世,德干溢流玄武岩喷发后,伸展在薄弱的地壳中继续,引起了孟买地堑和Surat坳陷沉降的加强、Seychelles微大陆从印度分离以及孟买高地上正断层的重新活动。孟买地堑和Surat(Danahu)坳陷在热沉降期间充填了富有机质页岩,在缓慢沉降的盂买台地上发育了始新-中新世浅水碳酸盐,海平面波动产生了次生孔隙的发育。晚第三纪成熟的Surat(Danahu)坳陷页岩生成烃类,运移至孟买高的碳酸盐储层。Canlpanian构造事件之后,Konkan—kerala和印度东海岸的较老盆地并未受到影响,缺乏有利的成藏要素是该地区的特点。  相似文献   
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