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1.
Studies of invertebrates from steppe patches in the tundra and taiga zones of Beringia provide additional evidence that these areas could be relict steppes. A number of insect species common to both modern relict steppes and fossil Beringian insect faunal assemblages have been found. These provide important information on the moisture and temperature preferences of some of the surviving members of Pleistocene steppe-tundra insect communities. The most significant species of West Beringian insects are weevils in the genus Stephanocleonus (Coleoptera, Curculionidae), indicators of thermophytic steppe, and the pill beetle Morychus viridis (Coleoptera, Byrrhidae), the indicator of hemicryophytic steppe. The East Beringian invertebrate population of relict steppe is substantially different. Fossil evidence suggests that biotic exchange between the two parts of Beringia was limited during the Pleistocene; populations of steppe insects did not move across the Bering Land Bridge (BLB), while tundra species had more flexibility. The tundra environment reconstructed for the Pleistocene BLB should have facilitated amphi-beringian distributions for most tundra invertebrate species, but apparently only a few species achieved this. 相似文献
2.
O. V. Serebrennikova E. B. Strel’nikova I. V. Russkikh 《Geochemistry International》2017,55(12):1090-1104
The paper presents chromatographic–mass spectrometric data on the individual composition of organic compounds in sapropel-like deposits of lakes in the steppe, forest–steppe, and three taiga natural climatic zones (NCZ) in Khakassia and western Siberia. Data on the individual composition of n-alkanes, carboxylic acids and their esters, thiophenes, phytol, phytone, steroids, and di- and triterpenoids and on their distribution in the sediments show systematic variations in the composition of the organic matter (OM) with increasing ambient temperature and the aridity of the climate. The concentrations of all groups of the compounds in lacustrine sediments decrease southward, and simultaneously esters with long (up to С20) alkyl substituents appear. The concentrations of oxygen-bearing compounds increase among the acyclic structures and triterpenoids, as also do the concentrations of structures ketonic substituents among the steroids. The dominance of the carboxylic acids and their esters by high molecular weight homologues gives way to the dominance of palmic acid and its derivatives. Among n-alkanes, the dominance of С27 and С29 hydrocarbons typical of terrestrial plants gives way to a higher percentage of homologues С21–С25 (macrophytes) and С31 (herbaceous plants). Among the tocopheroles, the concentration of the oxidized form of α-tocopherol (acetate) increases. 相似文献
3.
Milan Chytrý Michal Horsk Ji&#x;í Danihelka Nikolai Ermakov Dmitry A. German Michal Hjek Petra Hjkov Martin Ko
í Svatava Kube&#x;ov Pavel Lustyk Jeffrey C. Nekola V ra Pavelkov &#x;i
nkov Zdenka Preislerov Philipp Resl Milan Valachovi
《Boreas: An International Journal of Quaternary Research》2019,48(1):36-56
Steppe‐tundra is considered to have been a dominant ecosystem across northern Eurasia during the Last Glacial Maximum. As the fossil record is insufficient for understanding the ecology of this vanished ecosystem, modern analogues have been sought, especially in Beringia. However, Beringian ecosystems are probably not the best analogues for more southern variants of the full‐glacial steppe‐tundra because they lack many plant and animal species of temperate steppes found in the full‐glacial fossil record from various areas of Europe and Siberia. We present new data on flora, land snails and mammals and characterize the ecology of a close modern analogue of the full‐glacial steppe‐tundra ecosystem in the southeastern Russian Altai Mountains, southern Siberia. The Altaian steppe‐tundra is a landscape mosaic of different habitat types including steppe, mesic and wet grasslands, shrubby tundra, riparian scrub, and patches of open woodland at moister sites. Habitat distribution, species diversity, primary productivity and nutrient content in plant biomass reflect precipitation patterns across a broader area and the topography‐dependent distribution of soil moisture across smaller landscape sections. Plant and snail species considered as glacial relicts occur in most habitats of the Altaian steppe‐tundra, but snails avoid the driest types of steppe. A diverse community of mammals, including many species typical of the full‐glacial ecosystems, also occurs there. Insights from the Altaian steppe‐tundra suggest that the full‐glacial steppe‐tundra was a heterogeneous mosaic of different habitats depending on landscape‐scale moisture gradients. Primary productivity of this habitat mosaic combined with shallow snow cover that facilitated winter grazing was sufficient to sustain rich communities of large herbivores. 相似文献
4.
Accumulation of heavy metals in soil and uptake by plant species with phytoremediation potential 总被引：14，自引：1，他引：13
J. Nouri N. Khorasani B. Lorestani M. Karami A. H. Hassani N. Yousefi 《Environmental Earth Sciences》2009,59(2):315-323
Contamination of heavy metals represents one of the most pressing threats to water and soil resources, as well as human health.
Phytoremediation can be potentially used to remediate metal contaminated sites. In this study, concentrations of copper, zinc,
iron, and magnesium accumulated by native plant species were determined in field conditions of Hame Kasi iron and copper mine
in the central part of Iran in Hamadan province. The results showed that metal accumulation by plants differed among species
and tissue bodies. Species grown in substrata with elevated metals contained significantly higher metals in plants. Metals
accumulated by plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance exists
widely amongst them. The mentioned species could accumulate relatively higher metal concentrations far above the toxic concentration
in the plant shoots. With high translocation factor, metal concentration ratio of plant shoots to roots indicates internal
detoxification metal tolerance mechanism; thus, they have potential for phytoextraction. The factors affecting metal accumulation
by plant species including metal concentrations, pH, electrical conductivity, and nutrient status in substrata were measured.
Mostly, concentrations of zinc and copper in both aboveground and underground tissues of the plants were significantly, positively
related to their total in substrata, while iron, zinc, and copper were negatively correlated to soil phosphorus. 相似文献
5.
T. I. Moiseenko N. A. Gashkina M. I. Dinu T. A. Kremleva V. Yu. Khoroshavin 《Geochemistry International》2013,51(13):1031-1148
This paper reports the results of an extensive investigation of water chemistry in the small lakes of European Russia and Western Siberia along a climatic gradient. It was demonstrated that small lakes unaffected by any direct contamination can be used as indicators of natural geochemical conditions of water formation, as well as global and regional fluxes of airborne pollution and climate warming. A novel concept was developed for within- and between-zone variability in water chemistry over vast areas of tundra, taiga, forest, and steppe, and contributions of natural and anthropogenic factors to its formation under present-day conditions were estimated. A proposed predictive scenario showed that climate warming will result in an increase in water salinity in southern regions and ubiquitous phosphorus enrichment in terrestrial waters; the hydrologic and geochemical conditions of water formation in northern Siberia will change significantly in response to permafrost thawing. Zonal features in the development of anthropogenically-induced processes in terrestrial surface waters (acidification, eutrophication, and metal enrichment) were determined. It was demonstrated that, in addition to naturally acidified lakes with high contents of humic acids, acid lakes of anthropogenic origin occur over the whole humid region discussed here, and acidification processes were characterized for each subregion. The trophic status of lakes and limitation of their bioproductivity with respect to nutrients were estimated. The concentrations and distribution of trace elements were analyzed in terrestrial waters from various climatic zones of European Russia and Western Siberia, and the first estimates were obtained for the mean concentrations and coefficients of migration of a wide range of elements in terrestrial freshwaters. We distinguished a group of metal (Mo, As, U, Bi, Sb, Cd, Ag, Se, Re, Pb, Cd, W, etc.) the enrichment of which in natural waters results from their global dispersion in the environment. Experimental results and natural observations are presented on the processes of metal ion complexation with humus substances, and sequences of their increasing activity in competing for organic ligands were derived. Data are presented on the speciation of metals depending on natural water chemistry in the tundra, taiga, and steppe zones. The pioneering investigations on the geochemistry of natural waters allowed us to substantiate new regional norms for water quality. 相似文献
6.
7.
The eastern Pontides region is a mountainous terrain favourable for massive sulphide deposits. Besides the known deposits, it is highly likely that there are others to be discovered. This paper, therefore, describes the results of a soil and biogeochemical sampling program to assess the suitability of biogeochemical methods for the exploration of hidden deposits in temperate terrains. Soil sampling in the Pontides is shown to be a reliable follow-up method. It produced a significant geochemical response characterised by extensive Cu and Zn but localised Pb anomalies. Lead therefore is the element which can be used to pinpoint the mineralisation due to its relatively less mobile character. Hydromorphic dispersion enhanced the anomalies indicating that base of slope samples would produce reliable results. Of the plant species sampled, Corylus avellana (hazelnut tree) with deep penetrating roots shows comparable results to soil sampling and could be used to delineate the mineralisation. Rhododendron luteum may also be of help. In both species Pb shows limited dispersion and accumulates in the plants near the mineralised site whereas Cu and Zn tend to move away downslope. This shows that biogeochemical sampling could, with proper attention to species selection, be successfully used as an alternative method in the search of massive sulphide deposits in mountainous terrains with a high rainfall such as the eastern Pontides. 相似文献
8.
9.
基于多层次模糊综合优选找矿远景区 总被引：1，自引：0，他引：1
找矿远景区优选是矿产预测评价中的重要研究内容之一.文章利用多层次模糊综合评价的方法优选西藏冈底斯斑岩铜矿找矿远景区.实践结果表明:该方法不仅能够比较全面地考虑各种因素的影响及其相互作用,实现优选找矿远景区的合理、定量分析,并能在一定程度上反映出影响找矿远景区优选的关键因素,减少了人为主观因素,其优选结果具有客观性和科学性. 相似文献
10.
Lyudmila Mokhova Pavel Tarasov Valentina Bazarova Mikhail Klimin 《Quaternary Science Reviews》2009,28(25-26):2913-2926
In this study we present a recent compilation of 286 modern surface pollen spectra from the southern part of the Russian Far East (42–54°N, 131–141°E) and use it to test the biome reconstruction method. Seventy terrestrial pollen taxa were assigned to plant functional types and then classified to eight regional biomes. When applied to 286 surface pollen spectra, the method assigns about 70% (201 sites) of the samples to the cool mixed forest biome, 17% – to the taiga, 2% – to the cool conifer forest, 3% – to the temperate deciduous forest, and 7% – to the steppe. The steppe reconstruction is characteristic of the pollen spectra from the agricultural areas around Lake Khanka. A visual comparison shows good agreement between pollen-derived biomes and actual vegetation distribution in the region. However, pollen and botanical data, compared with the potential vegetation distribution simulated from the modern climate dataset using the BIOME1 model, demonstrate that spatial distribution of cool mixed forest is underrepresented in the model simulation. The model sets the mean temperature of the coldest month of −15 °C as the factor limiting distribution of the temperate deciduous broadleaf taxa, while vegetation and pollen data from the region demonstrate that this limit should be lowered to −26 °C. Application of the method to the Gur 3–99 pollen record (50°00′N, 137°03′E) demonstrates that tundra vegetation predominated around the site prior to 14 ka BP (1 ka = 1000 cal. years). However, the local presence of boreal trees and mixed forest-tundra vegetation is suggested by relatively high taiga scores. Soon after 14 ka BP the scores of taiga become slightly higher than tundra scores. During 11.4–10.5 ka BP a cool conifer forest is reconstructed. Establishment of the full interglacial conditions is marked by the onset of cool mixed forest by 10.5 ka BP. Between 10.3 and 2.5 ka BP the scores of temperate deciduous forest are close to those of cool mixed forest and become distinctly lower during the late Holocene. 相似文献
11.
This paper presents an integrated effort of a long-term risk analysis for the emergency response of nuclear power plants in
complex terrains. Use of coupled source term, fate and transport, and exposure assessment models associated with eight synoptic
weather patterns successfully provides timely and reasonably accurate long-range prognostic wind fields to simulate the possible
exposure episodes and risk potential. The seamless integration of multi-scale simulation models in accordance with different
release scenarios of process source term in the nuclear power plants permits the simulation of pollutant fate, transport,
and deposition processes in multiple dimensions of atmospheric environment. With the aid of spatial analysis, the assessment
of potential detrimental impacts for the accidental release of various nuclides from nuclear power plants becomes achievable.
The practical implementation of this integrated modeling system was assessed by case studies at one existing nuclear power
plant in southern Taiwan, China. Two- and three-dimensional fly-through visualization technologies make risk assessment practical
and credible based on the differing weather patterns identified at the continental scale in advance. 相似文献
12.
In recent years mineral exploration has concentrated on concealed deposits in regolith-covered terrains. In China, the regolith-covered landscapes mainly include desert windblown sand basins, desert peneplains, semi-arid grassland, loess plateaus, forestry land, alluvial plains and laterite terrains. These diverse regolith-covered areas represent geochemical challenges for mineral exploration in China. This paper provides an overview of recent progress on mechanisms of metal dispersion from the buried ore deposits through the transported cover to the surface and penetrating geochemical methods to detect the anomalies. Case studies show that, in arid and semi-arid desert sand-covered terrains, sampling of fine-fraction (− 120 mesh, < 0.125 mm) clay-rich horizon soil is cost-effective for regional geochemical surveys for sandstone-type uranium, gold, and base metal deposits. Fine-fraction sampling, selective-leaching and overburden drilling geochemical methods can effectively indicate the 210 gold ore body at Jinwozi goldfield. In alluvium-covered terrains, fine-grained soil sampling (− 200 mesh, < 0.074 mm) combined with selective leaching geochemistry shows clear ring-shaped anomalies of Cu and Ni over the Zhouan concealed Cu–Ni deposit. In laterite-covered terrains, the anomalies determined by the fine-fraction soils and selective leaching of absorbed metals on coatings of Fe–Mn oxides coincide well with the concealed deposit over the Yueyang ore deposits at the Zijin Au–Cu–Ag field. Nanoparticles of hexagonal crystals mainly native copper, gold and alloys of Cu–Fe, Cu–Fe–Mn, Cu–Ti, and Cu–Au were observed in gases, soils and ores using a transmission electron microscope (TEM). The findings imply that nanoparticles of gold and copper may migrate through the transported cover to the surface. Uranium is converted to uranyl ions [UO22 +] under oxidizing conditions when migrating from ore bodies to the surface. The uranyl ions are absorbed on clay minerals, because clay layers have a net negative charge, which needs to be balanced by interlayer cations. Nanoparticles of Au and Cu and ion complexes of U are more readily absorbed onto fine fractions of soils containing clays, colloids, oxides and organic matters. Thus, fine-grained soils enriched with clays, oxides and colloids are useful media for regional geochemical surveys in regolith-covered terrains and in sedimentary basins. Fine-fraction soil sampling combined with selective leaching geochemistry is effective for finding concealed ore bodies in detailed surveys. Penetrating geochemistry at surface sampling provides cost-effective mineral exploration methods for delineation of regional and local targets in transported cover terrains. 相似文献
13.
Florent Rivals Gina M. Semprebon 《Boreas: An International Journal of Quaternary Research》2017,46(2):254-263
The geographical distribution of species affects their dietary traits relative to resources available in different latitudes. Dietary traits of Rangifer tarandus, a species with a wide geographical distribution, were investigated using tooth mesowear and microwear methods in eight extant populations from Canada. The data show a latitudinal shift corresponding to a vegetational gradient from the taiga to the tundra, i.e. an increase of lichen consumption from the low to the high latitudes. This pattern is also evidenced in the Pleistocene fossil record of Europe where R. tarandus populations from low latitude localities show a lower consumption of lichen than at higher latitudes. 相似文献
14.
Yu. N. Vodyanitskii E. G. Morgun L. A. Obydenova K. A. Rumyantseva N. V. Chapygina 《Geochemistry International》2009,47(3):297-310
A method is proposed for determining the proportions of soluble Fe oxides (magnetite, FeOFe2O3, and maghemite, γ-Fe2O3) based on the measured magnetic susceptibility before and after treatment of soil with the Tamm or Mehra-Jackson (DCB) reagents. The development of hydromorphism in steppe soils in Ciscausiaia is associated with an increase in the magnetite fraction and, consequently, the average magnetite: maghemite ratio increases from 0.8–0.9 to 1.1. In these soils, smectites facilitate magnetite oxidation to maghemite. Soddy-podzolic and dark humic soils in the Cis-Ural region are noted for low values of the magnetite: maghemite ratio (0.5 on average) due to maghemite predominance. Soils in the Cis-Ural region on cover red-earth clays inherit lithogenic Fe oxides: hematite and maghemite. Hydromorphism in humid environments in northern taiga is accompanied by a significant increase in the magnetite: maghemite ratio to 4–9. Some issues of Fe geochemistry in magnetite and maghemite are considered. 相似文献
15.
为明确高寒草地土壤理化特征及金属元素在有机畜牧生产中的作用,选取青藏高原中东部高山嵩草草甸、草甸化草原、温性草原三种草地类型为研究对象,分析土壤理化性质和重金属元素,并探讨其影响作用。结果表明：三种草地类型群落盖度由大到小依次是高山嵩草草甸（91%） > 草甸化草原（85%） > 温性草原（75%）,草甸化草原的物种数最多达25种,分别是高山嵩草草甸和温性草原的1.47倍和1.92倍。温性草原0~10 cm土层容重分别是高山嵩草草甸和草甸化草原的1.89倍和1.40倍,10~20 cm土层容重分别是高山嵩草草甸和草甸化草原的1.42倍和1.29倍。高山嵩草草甸土壤有机质、全氮含量最高,有机质含量分别是草甸化草原、温性草原的1.20倍和2.65倍,全氮含量分别是草甸化草原、温性草原的1.18倍和2.47倍。温性草原土壤pH值最高达8.46,分别是草甸化草原和高山嵩草草甸的1.04倍和1.10倍。总体来看,重金属元素含量在高山嵩草草甸最高,温性草原最低,草甸化草原居中。三种草地类型土壤7种重金属元素含量都在一级以内,其生态危害指数未出现强污染状况,适合构建示范区发展有机畜牧业。 相似文献
16.
来自中国北方20个典型灌丛群落的54个表土样品的花粉组合特征研究表明除蒿及沙棘灌丛外,其它灌丛中的优势植物种类在表土花粉组合中的百分比多数低于20%。阔叶林区灌丛与荒漠区和草原区灌丛表土花粉组合差别较大。阔叶林区灌丛中常有一定量的中华卷柏,蒿属和藜科百分比之和低于40%,花粉类型多样性指数多高于2.0;而草原区及荒漠区中华卷柏很少出现,蒿藜百分比高于50%,花粉类型多样性指数多低于2.0。落叶阔叶林区灌丛花粉组合中,松蒿比(P/A)大于0.1,而草原及荒漠区灌丛则小于0.1,但草原区灌丛蒿藜比(A/C)大于1,荒漠区则小于1。将松蒿比(P/A)与蒿藜比(A/C)、花粉类型多样性指数联合起来可较好地将荒漠、草原及落叶阔叶林区灌丛分开。 相似文献
17.
《International Geology Review》2012,54(7):609-618
The use of plants as indicators in prospecting for minerals is discussed on a broad scale from the standpoints both of available literature and field experiments. The method of isoline mapping of mineral deposits by means of metal content in ashes of plant parts is detailed,. The author cautions against too broad use of any single species as a “direct” indicator or too heavy reliance on ash content, as some species tend to concentrate certain minerals, regardless of soil composition. Instead, a combination of species as indicators and a combination of factors, such as appearance of leaves, luxuriance of the plant, and color and time of blooms is recommended. The tendency of some minerals to nullify the effect of others–iron counteracting the effect of copper, for instance — is noted, as well as different effects on plants of different salts of the same mineral. In spite of these qualifications and the early, stage of development of this technique, the method has particular merit in areas where the strata overlying the metal-bearing deposits is relatively thick. Analyzing the ash content of leaves of deep-rooted trees is particularly helpful in detecting the presence of an ore mineral in such a situation. — A. Eustus 相似文献
18.
M. A. Ashraf M. J. Maah I. Yusoff 《International Journal of Environmental Science and Technology》2011,8(2):401-416
The degree of contamination by heavy metals (arsenic, copper, lead, tin and zinc) in soil and transfer to plants has been studied. Specimens of plant species from five locations in an area of 10 × 10 m were sampled with their corresponding soils. Thirty six plant species including two shallow water aquatic plants were identified. Soil and plant specimens were analyzed by using inductively coupled plasma optical emission spectrometry. It was found that metal concentration in soil was highly variable while concentration of metals in plants directly depends on the concentration of metals it was rooted. Roots showed highest metal concentration followed by leaves, shoots and flowers. Bioconcentraion factor and translocation factor were calculated, representing Cyperus rotundus L. as a potential tin-hyperaccumulator plant, previously not reported in literature. Plant Species Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were metal accumulator while Acacia podalyriaefolia G. Don, Bulb Vanisium, Dillenia reticulate King, Eugenia reinwardtiana, Evodia roxburghiania Hk. f. clarke, Gleichenia linearis, Grewia erythrocarpa Ridl., Manihot esculenta Crantz, Paspalum conjugatum Berguis, Passiflora suberosa, Saccharum officinarum, Stenochlaena palustris (Burm.) Bedd. and Vitis trifolia Linn. were tolerated plant species. All other studied plants were excluders. Identified plant species could be useful for revegetation and erosion control in metals contaminated ex-mining sites. Morphological changes such as reduction in size, change in color and deshaping have also been observed in plant species with high metal values. 相似文献
19.
Elevated copper concentrations were detected in 20 species from the 1913 herbarium collection of W.M. Docters van Leeuwen at Utrecht. These plants had been collected from Salajar Island (near Sulawesi), Indonesia. Anomalous copper concentrations ranged from 80–600 μg/g (dry weight) in leaves of these species. Values for the same species collected outside of Salajar were invariably far lower () and indicated that the Salajar samples may have been growing over copper-rich substrates. The area has not yet been investigated by other geochemical methods, though extrapolation from the adjacent coast of Sulawesi of presumably similar geology indicates the possibility that the biogeochemical anomalies could be caused by copper-rich tephrites. 相似文献
20.
本研究基于10′×10′空间分辨率运用GIS软件对中国植被分布地理配准数字化,提取获得196个优势植物的地理分布数据以及内插相关的气候因子,运用分位数函数计算获得各个植物地理分布的气候阈值; 在此基础上采用生物气候群组（BAGs）的分类方法,对196个优势植物气候因子数据进行聚类分析,同时结合中国植被的地理分布特征,最后划分出29个BAG组,包括13个乔木组(6个常绿阔叶和2个落叶阔叶群组,4个常绿针叶和1个落叶针叶群组)、10个灌木组(5个常绿灌木和5个落叶灌木群组)和6个草本组。本研究的BAGs划分是建立在较高空间分辨率和定量气候因子阈值的基础上,因此,通过计算获得BAGs气候阈值(包括每日温度变化幅度、地表霜冻频率、月均温度、月降雨量、相对湿度、日照时数和>5℃年积温等),运用生物圈碳循环CARAIB模型,模拟出中国19个生物群区的现代潜在分布。模拟结果较好地表达了中国植被类型的地理分布,尤其较详细地展示了热带、亚热带、温带和高原地区的不同植被类型地理分布格局,但由于东北地区、西部草原以及热带原生植被受人类活动严重干扰,使得模拟结果比该地区的原生植被地理分布的实际面积偏大。总体而言,本研究获得的29个生物气候群组对模拟现代生物群区分布提供了理想的分类依据,其气候阈值也是进行过去和未来生物群区模拟的重要参照数据。 相似文献