楚科奇海和加拿大海盆表层沉积物中好气异养细菌的地理分布     

高爱国  陈皓文 《极地研究》2007,19(3):231-238

本文用MPN法测定楚科奇海和加拿大海盆表层沉积物中好气异养细菌(GAB)的含量,并对其地理学分布进行分析。结果表明,研究区GAB的检出率高达100%。4℃时GAB的含量范围、平均含量为4.00×102-2.40×106个.g-1、1.71×106个.g-1。25℃时GAB的含量范围、平均含量为2.40×105-2.40×107个.g-1、1.10×107个.g-1。无论是含量范围,还是平均含量,均是25℃时的培养结果大于4℃时的培养结果。GAB含量的地理分布趋势是随纬度增高,含量呈降低趋势。在经度变化上则为由东向西,含量呈降低趋势。对沉积物所处水深的分析,表明其在4℃培养得出来的GAB含量随水深增加有下降的趋势,25℃培养出来的GAB含量受环境影响较小,与水深变化关系不明显。  相似文献   

灰色GM(1,1)残差修正模型在滑坡预测中的对比应用   总被引：2，自引：0，他引：2  

李秀珍  孔纪名  王成华 《山地学报》2007,25(6):741-746

在传统GM(1,1)模型的基础上,经过不同方式的残差修正,分别建立了一阶残差修正GM(1,1)模型和二阶残差修正GM(1,1)模型。根据滑坡的监测资料,对变形曲线为光滑型滑坡(如黄龙西村滑坡、某滑坡)和阶跃型滑坡(如新滩滑坡、洒勒山新滑坡)分别建立了传统GM(1,1)模型和一阶、二阶残差修正模型,并对不同滑坡各模型的预测精度进行了分析比较。结果表明,残差修正GM(1,1)模型的预测精度明显高于传统GM(1,1)模型的预测精度。对变形曲线为光滑型的滑坡,二阶残差修正GM(1,1)模型的预测精度一般高于一阶残差修正GM(1,1)模型的预测精度;对变形曲线为阶跃型的滑坡,一阶残差修正GM(1,1)模型的预测精度高于二阶残差修正GM(1,1)模型的预测精度。  相似文献   

Why is Shirase Glacier turning its flow direction eastward?     

Kazuki Nakamura  Koichiro Doi  Kazuo Shibuya 《Polar Science》2007,1(2-4):63-71

We applied an image correlation method to Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR) data obtained from 1996 to 1998 to examine flow velocity within Shirase Glacier, Antarctica. From the grounding line to the downstream region of the glacier, the obtained ice-flow velocity was systematically higher on the western streamline than the eastern. The differences between the two streamlines were 0.31 km/a in 1996 and 0.37 km/a in 1998, significantly larger than the error estimate of 0.03 km/a. The direction of ice flow was about 312° at the grounding line and changed to 327° at 10 km, 346° at 20 km and 2° at 30 km downstream from the grounding line. The total accumulated deflection is 50° to the east. Under the assumption of the conservation of ice mass across the glacier, the observed eastward change in flow direction can be explained by an asymmetric deepening of bedrock topography, that is, across the 8 km width of the glacier, the eastern side is 50 m (10%) deeper than the western side. This eastward turning of flow direction appears to be accelerated by tributary inlets, that flow to the north and northeast at 60–75% of the velocity of inlets on the western streamline.  相似文献   

Natural and anthropogenic aquatic environmental changes reconstructed by paleolimnological analyses in Lake Kitaura,central Japan     

Tomonori Naya  Yoshihiro Tanimura  Yutaka Kanai  Fujio Kumon  Kazuo Amano 《Journal of Paleolimnology》2007,37(4):547-563

In order to assess the recent anthropogenic environmental changes in Lake Kitaura, central Japan, changes during the past few centuries were reconstructed from results of radiometric and tephrochlonological age determination, magnetic susceptibility measurements, total organic carbon analyses, total nitrogen analyses and fossil diatom analyses on a sediment core from the lake. A total of six major and sub-zones are recognized according to the diatom fossil assemblages, and we discuss aquatic environmental change in Lake Kitaura mainly based on these diatom assemblage change. Zone Ia and Zone Ib (older than AD 1707) are marine to brackish. In Zone IIa (AD␣1707–AD 1836), most of the brackish diatoms disappeared, and were replaced by freshwater species indicating a decrease in salinity. We interpret the salinity decrease in Zone I–IIa as a sea-level fall during the Little Ice Age. The salinity of the lake decreased to near freshwater conditions in Zone IIb (AD 1836–AD 1970), which could arise from alteration in River Tone or development of a sandspit in the mouth of River Tone in addition to sea-level change. In Zone IIIa (AD 1970–AD 1987), the diatom assemblage indicates a freshwater environment, and sedimentation rates increase rapidly. These changes reflect sedimentary environment change and an ecosystem transition due to the construction of the tide gate. In Zone IIIb (AD 1987–AD 2002), the diatom flux (valves cm⁻² y⁻¹) increased and species composition changed. The changes in Zone IIIb show a good agreement with limnological monitoring data gathered from the lake. These paleolimnological data suggest that the recent human-induced changes of the aquatic environment of the lake after the 1970s exceed rates during the period concerned in this study.  相似文献   

Spatial Analysis Techniques as Successful Mineral-Potential Mapping Tools for Orogenic Gold Deposits in the Northern Fennoscandian Shield,Finland   总被引：1，自引：0，他引：1  

Vesa Nykänen  V. Juhani Ojala 《Natural Resources Research》2007,16(2):85-92

Geoscientific Information Systems (GIS) provide tools to quantitatively analyze and integrate spatially referenced information from geological, geophysical, and geochemical surveys for decision-making processes. Excellent coverage of well-documented, precise and good quality data enables testing of variable exploration models in an efficient and cost effective way with GIS tools. Digital geoscientific data from the Geological Survey of Finland (GTK) are being used widely as spatial evidence in exploration targeting, that is ranking areas based on their exploration importance. In the last few years, spatial analysis techniques including weights-of-evidence, logistic regression, and fuzzy logic, have been increasingly used in GTK’s mineral exploration and geological mapping projects. Special emphasis has been put into the exploration for gold because of the excellent data coverage within the prospective volcanic belts and because of the increased activity in gold exploration in Finland during recent years. In this paper, we describe some successful case histories of using the weights-of-evidence method for the Au-potential mapping. These projects have shown that, by using spatial modeling techniques, exploration targets can be generated by quantitatively analyzing extensive amounts of data from various sources and to rank these target areas based on their exploration potential.  相似文献   

近年国外传统村镇旅游研究进展及启示   总被引：1，自引：0，他引：1  

王莉  陆林  卢松 《地域研究与开发》2007,26(5):79-84

近年来,随着传统村镇旅游的日益兴起,有关传统村镇的旅游学研究日益受到学术界重视和关注.总结了国内外关于传统村镇的旅游学研究进展,指出国外研究成果主要集中在传统村镇旅游发展影响研究、传统村镇旅游发展与文化原真性保持之间的关系、传统村镇旅游可持续发展等方面.国内研究与之相比,在研究内容、方法、领域、深度等方面仍有很大差距,有待进一步扩展和深入.今后应注意以下几方面问题:研究内容流于表层,应加强研究领域的延伸和深度的扩展;研究方法、手段较为单一,研究理论和方法焏待提高;理论研究滞后于旅游发展实践的现状焏待改善.  相似文献   

National and institutional productivity and collaboration in Antarctic science: an analysis of 25 years of journal publications (1980–2004)     

Prabir G. Dastidar 《Polar research》2007,26(2):175-180

  相似文献   

基于3S技术和USLE的深圳市茜坑水库流域土壤侵蚀强度预测研究     

ZHAO Yan-xin  ZHANG Wan-shun  Wang Yan  Wang Ting-ting 《福建地理》2007,(3)

基于RS、GPS和GIS(3S技术)的集成提出了USLE 6大因子的算法,在建立的专题地理信息数据库基础上,运用USLE对深圳市茜坑水库流域的土壤侵蚀强度进行预测和估算.结果表明:整个流域90.5%的区域土壤流失强度为中度以下,强度侵蚀以上的区域虽然仅占整个流域面积的9.5%,但是年土壤侵蚀量达到了整个流域土壤侵蚀量的49.4%.流域土壤侵蚀强度和植被覆盖情况明显相关,茜坑水库流域的东北山区部分是整个流域的严重侵蚀区.研究证明:在3S技术集成支持下,采用USLE对流域的土壤流失强度进行预测和估算的方法具有直观、方便、快捷的优点,成果能充分满足小流域水土保持工作的需要.  相似文献   

Application of the normalized surface magnetic charge model to UXO discrimination in cases with overlapping signals     

F. Shubitidze  K. O'Neill  B.E. Barrowes  I. Shamatava  J.P. Fernndez  K. Sun  K.D. Paulsen 《Journal of Applied Geophysics》2007,61(3-4):292-303

This paper presents an application of the normalized surface magnetic charge (NSMC) model to discriminate objects of interest, such as unexploded ordnance (UXO), from innocuous items in cases when UXO electromagnetic induction (EMI) responses are contaminated by signals from other objects. Over the entire EMI spectrum considered here (tens of Hertz up to several hundreds of kHz), the scattered magnetic field outside the object can be produced mathematically by equivalent magnetic charges. The amplitudes of these charges are determined from measurement data and normalized by the excitation field. The model takes into account the scatterer's heterogeneity and near- and far-field effects. For classification algorithms, the frequency spectrum of the total NSMC is proposed and investigated as a discriminant. The NSMC is combined with the differential evolution (DE) algorithm in a two-step inversion procedure. To illustrate the applicability of the DE–NSMC algorithm, blind test data are processed and analyzed for cases in which signals from nearby objects frequently overlap. The method was highly successful in distinguishing UXO from accompanying clutter.  相似文献   

Application of Load/Unload Response Ratio in the Study of Seismicity in the Region of Iran     

Zhang Langping 《中国地震研究》2007,21(2):147-155

The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and analysed in this paper. The tempo-spatial scanning of LURR in the region of Iran during January 1, 2003 to March 31, 2006 has been conducted, with 1 year as a time-window, 1 month as a time-step, and the comparison of the LURR anomalous regions in 2004 with the actual earthquakes with M≥5.0 in the next year (2005) is also given, which shows that 11 earthquakes with M≥5.0 occurred in LURR anomalous regions while 12 earthquakes with M≥5.0 in LURR regions in 2005. Furthermore, the seismicity in this region is studied by investigating the evolvement of the anomalous LURR regions.  相似文献