共查询到20条相似文献，搜索用时 140 毫秒
1.
Minority population and sustainable development in mountain regions a case study of the Tibetan inhabited region in Sichuan, China 总被引：1，自引：0，他引：1
《地理学报(英文版)》1998,(4)
ＩｎｔｒｏｄｕｃｔｉｏｎＳｕｓｔａｉｎａｂｌｅＤｅｖｅｌｏｐｍｅｎｔｈａｓｂｅｃｏｍｅａｃａｔｃｈｗｏｒｄｉｎｔｈｅｐｒｅｓｅｎｔｗｏｒｌｄｓｉｎｃｅｔｈｅＳｕｍｍｉｔＭｅｅｔｉｎｇｉｎＲｉｏｄｅＪａｎｅｉｒｏｉｎＪｕｎｅ1992(ＵＮＣｏｎｆｅｒｅｎｃｅｏｎＥｎｖｉｒｏｎｍｅｎｔａｎｄＤｅｖｅｌｏｐｍｅｎｔ).Ａｌｔｈｏｕｇｈｉｔｉｓｎｏｔａｃｏｎｃｅｐｔｔｈａｔｃａｎｂｅｕｓｅｄａｓａｂａｓｉｓｆｏｒｅｉｔｈｅｒｔｈｅｏｒｙｏｒａｃｔｉｏｎ(Ｗｉｂａｎｋｓ,1994)ａｎｄｍｅａｎｓｄｉｆｆｅｒｅｎｔｔｈ… 相似文献
2.
3.
The 40 Ar 39 Ar ages of hornblendes in Grt Pl bearing amphibolite from the Larsemann Hills, East Antarctica and their geological implications 
下载免费PDF全文
下载免费PDF全文 １ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｐａｒｔｏｆｅｘｔｅｎｓｉｖｅｌａｔｅＰｒｏｔｅｒｏｚｏｉｃｍｏｂｉｌｅｂｅｌｔｏｆＥａｓｔＡｎｔａｒｃｔｉｃａ,ｔｈｅｕｐｐｅｒａｍｐｈｉｂｏｌｉｔｅｔｏｇｒａｎｕｌｉｔｅｆａｃｉｅｓｈｉｇｈ－ｇｒａｄｅｍｅｔａｍｏｒ... 相似文献
4.
5.
An unidentified geophysical event recorded with L&R-ET gravity meter at Zhongshan Station,Antarctica 下载免费PDF全文
下载免费PDF全文 ＡｎｕｎｉｄｅｎｔｉｆｉｅｄｇｅｏｐｈｙｓｉｃａｌｅｖｅｎｔｒｅｃｏｒｄｅｄｉｔｈＬ＆Ｒ－ＥＴｇｒａｖｉｔｙｍｅｔｅｒａｔＺｈｏｎｇｓｈａｎＳｔａｔｉｏｎ，ＡｎｔａｒｃｔｉｃａTX＠郝晓光Ａｎｕｎｉｄｅｎｔｉｆｉｅｄｇｅｏｐｈｙｓｉｃａｌｅｖｅｎｔｒｅｃｏｒ... 相似文献
6.
7.
中国农村资源,环境与发展的可持续性评估：SEEA方法及其应用 总被引：19，自引：4，他引：15
基于一体化核算体系（Ｓｙｓｔｅｍ ｏｆ Ｅｎｖｉｒｏｎｍｅｎｔａｌ－Ｅｃｏｎｏｍｉｃ Ａｃｃｏｕｎｔｉｎｇ简写为ＳＥＥＡ）分析１９９０￣１９９６年间中国农村的资源净产值、环境净产值和真实储蓄。表明中国农村经济发展的资源与环境代价巨大。资源净产值每年损失幅度为２１￣１４２６亿元,平均占农村总产值的１．７２％;环境净产值每年损失幅度为６０４￣１０５９亿元,平均占农村总产值的２．３３％;真实储蓄在－１２ 相似文献
8.
测定了三元体系ＲＥＣｌ３（ＲＥ＝Ｄｙ，Ｙｂ）－ＨＯＡｃ－Ｈ２Ｏ（３０℃）的平衡态的溶度数据并绘制了相应的溶度图。在两个体系中分别得到了ＤｙＣｌ３．６Ｈ２Ｏ和ＹｂＣｌ３．６Ｈ２Ｏ两种固相。依据ＨＯＡｃ和ＤｙＣｌ３．６Ｈ２Ｏ和ＹｂＣｌ３．６Ｈ２Ｏ有盐析作用这一结论得到了一种制备ＤｙＣｌ３．６Ｈ２Ｏ和ＹｂＣｌ３．６Ｈ２Ｏ的ＨＣｌ－ＨＯＡｃ法。同时， 在分析测定酸的重百分浓度时，利用“差减法”得到了Ｈ的准 相似文献
9.
10.
用NCEP／NCAR再分析辐射资料估算月平均地表反照率 总被引：16，自引：1，他引：15
本文利用１９７９年￣１９９５年１７年平均的ＮＣＥＰ／ＮＣＡＲ（Ｎａｔｉｏｎａｌ Ｃｅｎｔｅｒ ｆｏｒ Ｅｎｖｉｒｏｎｍｅｎ－ｔａｌ Ｐｒｅｄｉｃｔｉｏｎ／Ｎａｔｉｏｎａｌ Ｃｅｎｔｅｒ ｆｏｒ Ａｔｍｏｓｐｈｅｒｉｃ Ｒｅｓｅａｒｃｈ,美国国家环境预报中心／美国国家大气研究中心）再分析辐射资料估算了全球月平均地表反照率．从所得结果的时空分布来看,用ＮＣＥＰ／ＮＣＡＲ辐射资料得到的全球地表反照率基本 相似文献
11.
渤海湾北岸表层沉积中的有孔虫群及其生态环境 总被引：2，自引：0，他引：2
我们对渤海湾北岸177个表层沉积物样品进行了有孔虫分析。经鉴定,未发现浮游有孔虫,底栖有孔虫共计82种,其中包括一新种Jadammina planata He et Li sp.nov.根据不同的环境中沉积物内有孔虫群属种组合不同,大体可归纳为二种组合:一是河口、海滩、泻湖、滨海平原等滨海边缘环境组合,在南堡以东该组合称为厚壁转轮虫——显孔鼓室希望虫组合,南堡以西称为厚壁转轮虫——多变假小九字虫组合,二是分布在水深10米以内的近岸浅海环境组合,称为厚壁转轮虫——缝裂希望虫组合。在不同环境中,有孔虫壳体数量的变化是有规律的,一般在泻湖中有孔虫含量最多,滨岸沙坝处最少,沙坝脊部有时为零,向海方向至近岸浅海共含量又有逐渐增多的趋势。 相似文献
12.
The Present foraminiferal distribution (live + dead) in Freemansundet between Barentsøya and Edgeøya, Svalbard, has been compared with assemblages in raised marine Holocene deposits in Guldalen on Edgeeya. Four distinct foraminiferal assemblages were identified in Freemansundet, the Elphidium excavatum-Cassidulina reniforme assemblage, the Elphidium hallandense assemblage, the Cibicides lobatulus assemblage and the Elphidium incertum-Haynesina orbiculare assemblage. Four assemblage zones (Zones A-D) have been established in the glaciomarine to marine sediment sequence in Guldalen. Only two of the recent fauna! types were represented here. The Elphidium excavatum-Cassidulina reniforme assemblage, which reflects a proximal glacier environment, was found in the lowermost Zone A (the Elphidium excavatum Zone) and in Zone C (the Elphidium excavatum-Cassidulina reniforme Zone) in the Guldalen stratigraphy; the Elphidium incertum-Haynesina orbiculare assemblage, which reflects ameliorated shallow water conditions, was found in the uppermost Zone D in Guldalen. The marine sequence in Guldalen represents a relatively short period of time during the Early Holocene (ca 9700 to 8300 BP). The succession of the foraminiferal assemblages suggests that the deglaciation was interrupted by a cold period with glacial stagnation just after 9600 bp (Zone B. the Astrononion gallowayi-Nonionellina labradorica Zone). 相似文献
13.
南极乔治王岛长城湾活有孔虫和死有孔虫的比较分析 总被引：1，自引：0，他引：1
本文对中国首次南极考察队在长城湾采集的海底底质样品作了有孔虫分析,初步查明有孔虫属种,并揭示了长城湾有孔虫组合和分布规律。 相似文献
14.
15.
Sediment chemistry and arcellacean community composition were analyzed to study the ecological effects of copper mine-derived acidic and metal-rich waters in a freshwater bay in eastern Finland. To track spatial and temporal changes in the bay, 32 mine-impacted (top) and pre-impact (bottom) samples were analyzed from 16 short sediment cores taken along a transect extending from the pollution source. In addition, short cores from the impacted and reference sites were studied. Recent sediments displayed a geochemical gradient from the inner bay, where mine water is discharged, to the outer bay. Inner bay sites were enriched with C, S, and Fe, whereas Mn was depleted, but has precipitated in the outer bay. Among the heavy metals, Cu, Al, Zn, and Ni concentrations had increased in the inner and mid bay, while Co and Cd concentrations had increased at mid-bay sites. The change from the natural to mine-impacted condition was also seen in faunal gradients. According to ordination and distance measures, the greatest changes in species composition occurred in the inner bay, with fairly small changes in the outer bay. Numerical methods suggested that metals (Cu, Pb, Al, Zn, Cr), redox-sensitive elements (Fe, Mn), organic carbon and nutrients could be related to changes in arcellacean assemblages. Geochemical changes in the impacted core started at ~20 cm with increases in S alternating with peaks in Cr and Mg. Heavy metal concentrations increased markedly at 10 cm, after the active mining period, suggesting the beginning of acid mine drainage. Geochemical changes at ~20 cm were already apparent in the arcellacean assemblages, but the most notable change coincided with the geochemical shift at 10 cm, with signs of decreased pH. Numerical methods suggest that mining-related metals Co, Cu, Zn and Ni co-vary with arcellaceans, but Al appears to behave independently with respect to the species data. 相似文献
16.
本文分析了西格陵兰Disko湾的表层沉积物硅藻,发现并统计了分属于39个属的78个硅藻种及其变种。应用对应分析方法,对Disko湾表层沉积硅藻组合进行了分类:组合Ⅰ为Fragilariopsis cylindrus-Fragilariopsis oceanica组合,主要分布在西格陵兰Disko湾南部的近岸和外海处;组合Ⅱ为Detonula confervaceae休眠孢子-Thalassiosira nordenskioeldii组合,都分布在Dis-ko湾北部海域。其中,根据海流等环境要素的不同,组合Ⅰ又可进一步划分为两个亚区:组合Ⅰa为F.cylindrus-F.oceanica-Pauliella taeniata组合,主要分布于沿岸海区;组合Ⅰb为F.cy-lindrus-F.oceanica-Thalassiosira antarcticavar.borealis休眠孢子-Thalassiosiracf.antarcticavar.borealis组合,分布于外海区域。 相似文献
17.
Spatial variability of chironomid death assemblages in the surface sediments of a fluctuating tropical lake (Lake Naivasha,Kenya) 总被引：1，自引：0，他引：1
Studies addressing within-lake variability of fossil chironomid assemblages are very few, and all deal with hydrologically
stable temperate lakes where the question of spatial integration mostly relates to the mixing of faunal assemblages associated
with shallow, warm-water habitat and those associated with deeper, cold-water habitat. Here we study within-lake variability
of surface-sediment chironomid assemblages in the fairly large (∼100–170 km2 since 1983) and shallow (Z
max = 5–8 m) fluctuating tropical lake basin of Lake Naivasha, Kenya, and compare the patterns observed with those in two smaller
adjacent basins, one similarly shallow (Lake Oloidien, 5.1–5.7 km2, 5–8 m), the other deep and stratified (Crescent Island
Crater, 1.9 km2, 14–17 m). Chironomid assemblages were analysed in core-top samples and surface sediments along inshore to offshore transects,
and how well individual samples represented the total (basin-wide mean) subfossil assemblage was considered both in terms
of taxon richness and taxon percent composition. Within-lake variability of subfossil chironomid concentrations (with generally
higher absolute values in nearshore samples) could be explained by effects of sediment winnowing and focusing, whereas between-lake
variability reflected their relative susceptibility to wind-driven sediment disturbance or bottom anoxia. In all study lakes,
but most significantly in lakes Naivasha and Oloidien, species distribution in the subfossil chironomid assemblages showed
a strong nearshore to offshore gradient, which in these shallow lakes, reflects the dominant control of substrate and food
quality on species distribution in the living community. Particularly in the larger basins, nearshore samples better represented
the total lake assemblage than offshore samples, because the former always contained a component of mud-dwelling species whereas
the latter often lacked a component of macrophyte-dwelling species. Our results show that although sedimentation dynamics
in the shallow, wind-stressed Lake Naivasha is dominated by frequent resuspension and random sediment redistribution, the
near- to offshore gradient in chironomid habitat remains imprinted on subfossil assemblages. We conclude that also in shallow
fluctuating lakes, given sufficient size, incomplete pre-burial spatial integration of habitat-specific chironomid assemblages
can be exploited for within-lake calibration of environmental gradients. 相似文献
18.
Adriana García 《Journal of Paleolimnology》1999,21(3):307-323
Charophyte (Charales, green macroscopic algae) assemblages found in Quaternary shoreline sediments from Salina del Bebedero, Argentina, are described in detail, illustrated, and statistically analysed. Fossil gyrogonites, Late Pleistocene and Holocene in age, of Chara cf. hispida var. major (Hartman) Wood, Chara halina García, Chara hornemannii Wallmann, Chara bulbillifera (Donterberg) García, Lamprothamnium haesseliae Donterberg and Lamprothamnium succinctum (Braun ex Ascherson) Wood were identified. A comparison with extant charophyte species of similar ecological requirements allowed for an accurate systematical determination and provided useful data for complementary palaeoecological and palaeobiogeographical approaches. On this basis, a reconstruction of palaeo-salinities for the Salina del Bebedero lake, represented by eleven palaeo-beaches, is proposed. Also the associations of charophytes with the ostracods Cyprideis sp., Limnocythere sp., Pampacythere sp., Cypridopsis sp., Darwinula sp., Ilyocypris gibba (Randohr) Brady and Norman, and the foraminifers Ammonia sp., Elphidium gunteri Cole, Quinqueloculina sp., and one species of Discorbacea are analysed, since they are present in both the fossil and modern environments. 相似文献
19.
Ara Cho Daekyo Cheong Jin Cheul Kim Dong-Yoon Yang Jin-Young Lee Kaoru Kashima Kota Katsuki 《Journal of Paleolimnology》2018,60(4):553-570
Hwajinpo is the largest lagoon in Korea and is located along the east coast of the country. It possesses Holocene sediments that provide an important record of past climate change. We studied the evolution of Hwajinpo Lagoon using grain size data and diatom assemblages in an 11.0-m core (HJ02), which was obtained at the mouth of a small river that drains into the lagoon. Core chronology was established with accelerator mass spectrometry 14C dates and optically stimulated luminescence dates. Diatom assemblages and grain size analysis revealed that estuarine conditions in the inner lagoon area transitioned to an open embayment ca. 8 ka as a result of sea-level rise. Around 7.8 ka, the open bay became a semi-closed bay as a consequence of development of a sand barrier. After the bay was semi-closed, marine water inflow was increasingly restricted as the sand barrier developed, and the semi-closed bay became a completely enclosed, low-salinity, brackish lagoon around 6 ka. There was an erosional hiatus between 5.5 and 1.7 ka (7.0 m depth), likely caused by river flooding and a switch in the location of drainage along the delta. The lagoon became oligohaline around 1.6 ka, likely because of increasing precipitation associated with an intensified Asian summer monsoon. This increase in precipitation resulted in expansion of the sand bar by sediment inflow, driven by agricultural development in the area. About 1000 years ago, the diatom assemblage was similar to the modern assemblage, suggesting the lagoon’s current geomorphic conditions had been established. 相似文献
20.
Dorthe Klitgaard-Kristensen Hans Fetter Sejrup Haflidi Haflidason 《Polar research》2002,21(2):275-282
This paper compiles new and previously published data on recent calcareous benthic foraminifera (dead and living assemblages) in surface sediment samples from the northern North Sea area, focussing on the dead benthic foraminifera and their relation to the environment. Five dead benthic foraminiferal assemblages have been identified. In Scottish coastal areas Cibicides lobatulus and Rosalina sp. dominate in areas with strong current activity and coarse-grained sediments, whereas C. lobatulus and Trifarina angulosa dominate at similar conditions in the Norwegian coastal areas. Cassidulina laevigata assemblages occur in areas influenced by inflow of Atlantic water into the northern North Sea. In the central part of the Norwegian Channel Uvigerina mediterranea prevails in fine-grained sediments with high organic content and possibly low oxygen content. This species' restricted distribution to the Norwegian Channel could possibly be related to the availability of food. Bulimina marginata and Hyalinea balthica dominate on the Fladen Ground where seasonal stratification is pronounced. This presumably leads to a decrease in the oxygen content in the bottom-waters during part of the year. 相似文献