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111.
该文以青岛市经济技术开发区为研究区域,利用2003,2007和2010年3个时相的遥感影像,分析了土地利用的变迁状况。研究表明,在研究时段的7年间,耕地面积减少趋势显著,总面积减少了1 727.00hm2;另一方面工矿仓储用地面积直线上升,总面积增加了1 703.12hm2。总体上来说,主要表现为耕地向工矿仓储用地和城镇住宅用地的转化,两者的转化量分别占耕地减少总面积的71.16%和14.35%;其次是林地和空闲地向工矿仓储用地的转化,前者的转化量占林地减少总面积的68.86%。  相似文献   
112.
为进一步探明岗讲斑岩铜-钼矿床蚀变和矿化结构,有效指导下一步勘查工作,利用短波红外光谱技术对矿床内典型剖面上的4个钻孔进行了系统的测试分析.共检测到绢云母类、高岭石类、绿泥石类、硫酸盐类和碳酸盐类等蚀变矿物,其中尤以绢云母类矿物最为发育.对绢云母进行短波红外光谱测试分析显示:在靠近矿体的位置,有较大的伊利石结晶度(≥1.5)和较小的绢云母Al-OH吸收位置(≤2 205 nm);而在远离矿体的位置伊利石结晶度和绢云母Al-OH吸收位置分别为0.8~1.2和2 207~2 209 nm.同时,铁氧化物强度值与氧化矿体的出现具有同步性.表明短波红外光谱的这些特征参数有助于进一步理解岗讲斑岩铜-钼矿床蚀变和矿化结构,有效识别成矿流体性质,有潜力成为该矿区及其他类似矿区有效的找矿指标.  相似文献   
113.
Zhang  Chi  Wu  Shaohong  Leng  Guoyong 《地理学报(英文版)》2020,30(8):1219-1232
Journal of Geographical Sciences - Based on simulations by the Beijing Climate Center climate system model version 2 (BCC-CSM2), the possible changes in net primary productivity (NPP) of the...  相似文献   
114.
Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ13C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ13C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments. In addition to the 91 surface sediment samples, other materials collected in this study cover the main sources of organic material to estuarine sediment. These are: terrestrial organic matter (TOM), including plants and soil samples from the catchment; estuarine and marine suspended particulate organic carbon (POC) from both summer and winter. Results show that the average δ13C of estuarine surface sediment increases from −25.0 ± 1.3‰ in the freshwater environment to −21.0 ± 0.2‰ in the marine environment, with C/N decreasing from 15.2 ± 3.3 to 6.8 ± 0.2. In the source areas, C3 plants have lower δ13C than C4 plants (−29.0 ± 1.8‰ and −13.1 ± 0.5‰ respectively). δ13C increases from −28.3 ± 0.8‰ in the forest soil to around −24.1‰ in both riverbank soil and mangrove soil due to increasing proportion of C4 grasses. The δ13CPOC increases from −27.6 ± 0.8‰ in the freshwater areas to −22.4 ± 0.5‰ in the marine-brackish-water areas in winter, and ranges between −24.0‰ in freshwater areas and −25.4‰ in brackish-water areas in summer. Comparison of the δ13C and C/N between the sources and sink indicates a weakening TOM and freshwater POC input in the surface sedimentary organic matter seawards, and a strengthening contribution from the marine organic matter. Thus we suggest that bulk organic δ13C and C/N analysis can be used to indicate sources of sedimentary organic matter in estuarine environments. Organic carbon in surface sediments derived from anthropogenic sources such as human waste and organic pollutants from industrial and agricultural activities accounts for less than 10% of the total organic carbon (TOC). Although results also indicate elevated δ13C of sedimentary organic matter due to some agricultural products such as sugarcane, C3 plants are still the dominant vegetation type in this area, and the bulk organic δ13C and C/N is still an effective indicator for sources of organic matter in estuarine sediments.  相似文献   
115.
松嫩平原湖泊的分类与分区   总被引:19,自引:4,他引:15  
吕金福  李志民 《地理科学》1998,18(6):524-530
松嫩湖泊群的湖泊具有面积小,湖盆浅,密度大,类型多的特点。根据“成因-水量-水质”三要素的综合分类方案,运用三要素的三个主导指标和三个辅助指标,简明地将松湖泊进行了分类。根据湖泊群的区域环境及湖泊主导类型与类型结合的区域差异,将松嫩湖泊群划分为6个亚区。  相似文献   
116.
The Makgadikgadi–Okavango–Zambezi basin (MOZB) is a structural depression in the south-western branch of the East African Rift System of the northern and middle Kalahari, central southern Africa. In the present day, the mainly dry subbasins of the MOZB are part of a long-lived lacustrine system that has likely existed since Early Pleistocene and from which an extant freshwater fish radiation emerged seeding all major river systems of southern Africa. During hydrologically favourable periods the subbasins were connected as a single mega-lake termed Lake Palaeo-Makgadikgadi. Previous geomorphological studies and OSL dates have provided evidence for repeated mega-lake periods since approximately 300 ka. The environmental and climatic implications of such large scale late Quaternary lake-level fluctuations are controversial, with the duration of mega-lake phases poorly constrained. Here, we present the first evidence for a Marine Isotope Stage (MIS) 5 mega-lake period (about 935–940 m a.s.l.) reconstructed from a diatom-rich, 30-cm-thick lacustrine sediment section, exposed close to a palaeo-shoreline of the Makgadikgadi Basin. Based upon the environmental setting and in comparison with sedimentation rates of other similar lake environments, we tentatively estimated that the highstand lasted approximately 1 ka during MIS 5d–b. The 30-cm section was sampled in 0.5-cm steps. Diatom species diversity ranges from 19 to 30 through the section. The dominant species are Pseudostaurosira brevistriata, Rhopalodia gibberula, Cyclotella meneghiniana and Epithemia sorex. The total of 60 sediment samples provide us with a record at decadal to bi-decadal resolution. Based on diatom assemblages and their oxygen isotope composition (δ18O) we infer an alkaline and mostly oligohaline lake with shallow water conditions prevailing in MIS 5, and is potentially analogous to a Heinrich event. The climate over southern Africa during MIS 5 has been considered very arid but the hydromorphological context of our sediment section indicates that we captured a mega-lake period providing evidence that short-term excursions to significantly higher humidity existed. A hydrologically more favourable environment during MIS 5 than formerly presumed is in line with the early human occupation of the Kalahari.  相似文献   
117.
南极普里兹湾沉积物稀土元素地球化学特征   总被引:1,自引:0,他引:1       下载免费PDF全文
利用中国第29次南极科学考察在南极普里兹湾获取的3个短柱样品,进行了稀土元素测试分析,探讨了普里兹湾海洋沉积物稀土元素特征、分布模式及其控制因素。结果表明,普里兹湾各站沉积物中稀土元素含量各异,但均具有与上陆壳、中山站变质岩相似的页岩标准化配分模式,整体表现为轻稀土富集型,说明其物源一致,具有明显的大陆地壳来源特征。结合沉积物粒度、化学元素、生源指标等分析其分布及富集规律,发现物源是控制研究区稀土元素组成的主要因素,同时生物作用会对稀土元素的含量产生稀释,但"粒度效应"在此并不明显。普里兹湾沉积物短柱稀土元素参数垂向变化,反映了百年尺度内物源输入、沉积环境的变化。各站δCe值普遍具有向下减小的趋势,反映了随深度增加沉积环境的氧化性逐渐减弱的特征。  相似文献   
118.
随着我国经济建设的蓬勃发展,工农业和城市生活产生的污染物日益增多。如何处理这些污染物成了一个急待解决的问题。将污染物化有毒为无毒,当然是最彻底的办法,但这样做花费巨大,我们目前尚难做到。目前最常用的办法是将污染物排放人海。但过多的排放,超过了海洋的自净能力,就会污染海洋环境和海洋资源,进而影响人民的健康。所以,须要对污染物排放人海的方式、地点等加以选择,并对其排放人海的数量、速率等加以控制。这就要求我们了解海区对污染物的净化能力和在国家规定的标准下海区对污染物的最大容量。为了很好地解决这个问题,我们必须了解特定海区对污染物的稀释扩散起重要作用的海水运动情况。1984年5, 8, 10三个月,我们在渤海湾海河口区进行了海上调查,并结合历史资料,以COD 为指示因子,进行了渤海湾有机污染物在潮流作用下稀释扩散的数值计算。  相似文献   
119.
Numerous tephra dispersion and sedimentation models rely on some abstraction of the volcanic plume to simplify forecasts of tephra accumulation as a function of the distance from the volcano. Here we present solutions to the commonly used advection–dispersion equation using a variety of source shapes: a point, horizontal and vertical lines, and a circular disk. These may be related to some volcanic plume structure, such as a strong plume (vertical line), umbrella cloud (circular disk), or co-ignimbrite plume (horizontal line), or can be used to build a more complex plume structure such as a series of circular disks to represent a buoyant weak plume. Basing parameters upon eruption data, we find that depositions for the horizontal source shapes are very similar but differ from the vertical line source deposition. We also compare the deposition from a series of stacked circular disk sources of increasing radius above the volcanic vent with that from a vertical line source.  相似文献   
120.
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