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《盐湖研究》2019,(2)
<正>Profile Prof.Zeng De-wen obtained his bachelor Degree(1989) and Master Degree(1992) of the major"Nonferrous metallurgy"in Central South University(CSU),China.After several years of work as research assistant in CSU he was enrolled as Ph.D.student in the Technische Univerisatt Bergakademie Freiberg Germany,under the instruciion of Prof.Wolfgang Voigt in 1999.After 相似文献
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《盐湖研究》2019,(2)
<正>Profile Prof. Fang Chun-hui,as the Second Grade Professor and Doctoral Supervisor,was born in Xianyang City,Shaanxi Province,China,in 1957.He was admitted to the Chemistry Department,Northwestern University,China,after resumed the college entrance examination in 1977,He has been engaged in sci- 相似文献
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Flood risk forecast for China’s Poyang Lake region 总被引：2，自引：0，他引：2
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XINGKexia GUOHuaicheng SUNYanfeng HUANGYongtai 《地理学报(英文版)》2005,15(1):37-43
Water-quality deterioration and eutrophication of the Lake Dianchi have acquired more and more attention in the last few decades. In this paper, the spatial and temporal eutrophication status of the Lake Dianchi was assessed. The comprehensive trophic state index was chosen to assess the trophic status of the Lake Dianchi in the past 13 years. The result reveals that the trophic condition of Caohai is more serious than that of Waihai. Most of time Caohai was in extremely hypereutrophic state from 1988 to 2000. The trophic condition of Waihai had a worsening tendency from 1988 to 2000. Waihai was in eutrophic state before 1995, but it got in a hypereutrophic state after 1995. It was pointed out that TN and TP were the two biggest contributors of CTSIM in both Caohai and Waihai. 相似文献
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The Dongting Lake is located in the south beach of the middle reaches of the Yangtze River. Its catchment, with an area of 262,823 km2 or about 12% of the total Yangtze River catchment, is situated between 28o43?29o32扤 and 112o54?113o8扙, and crosses Hubei and Hunan provinces in administrative division. The main tributaries include Xiangjiang, Zishui, Yuanjiang, Lishui rivers (4 Tributaries) and some local rivers, such as Miluo River, Xinqiang River and other little streams. In the nor… 相似文献
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Celia Martín-Puertas Blas L. Valero-Garcés M. Pilar Mata Ana Moreno Santiago Giralt Francisca Martínez-Ruiz Francisco Jiménez-Espejo 《Journal of Paleolimnology》2011,46(3):405-421
High-resolution geochemical analysis of a 6-m-long sediment core from Zoñar Lake, southern Spain, provides a detailed characterization of major changes in lake and watershed processes during the last 4,000 years. Geochemical variables were used as paleolimnological indicators and complement Zoñar Lakes’s paleoenvironmental reconstruction based on sedimentological and biological proxies, which define periods of increasing allochthonous input to the lake and periods of dominant autochthonous sedimentation. Chemical ratios identify periods of endogenic carbonate formation (higher Ca/Al, Sr/Al and Ba/Al ratios), evaporite precipitation (higher S/Al, Sr/Al ratios), and anoxic conditions (higher Mo/Al, U/Th ratios and Eu anomaly). Higher productivity is marked by elevated organic carbon content and carbonate precipitation (Mg/Ca). Hydrological reconstruction for Zoñar Lake was based on sedimentological, mineralogical and biological proxies, and shows that lower lake levels are characterized by Sr-rich sediments (a brackish lake with aragonite) and S-rich sediments (a saline lake with gypsum), while higher lake levels are characterized by sediments enriched in elements associated with alumino-silicates (Al, K, Ti, Fe, trace and rare earth elements), reflecting fresher conditions. Geochemical indicators also mark periods of higher detrital input to the lake related to human activity in the watershed: (1) during the Iberian Roman Humid Period (650 BC–AD 300), around the onset of the Little Ice Age (AD 1400), during the relatively drier Post-Roman and Middle Ages (AD 800–1400), and over the last 50 years, due to mechanized farming practices. Heavy metal enrichment in the sediments (Cu and Ni) suggests intensification of human activities during the Iberian Roman Period, and the use of fertilizers during the last 50 years. 相似文献
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We used ostracod species assemblages and their δ18O values in a 32-m sediment core from Lake Qinghai, China, along with information from cores collected at other sites in the lake, to infer lake evolution and hydroclimate changes since the last glacial. Dominant ostracod species Ilyocypris bradyi and its low δ18O values showed that Lake Qinghai was small in size or even consisted of several playa lakes, and the 1F core site could have even been in a wetland setting, under cold and dry climate conditions before 15.0 ka. Presence of Limnocythere inopinata with low δ18O values, and absence of I. bradyi after 15.0 ka, indicate the lake area increased or that the playas merged. The decrease or disappearance of ostracods with high δ18O values showed that the lake shrunk under dry climate from 12.0 to 11.6 ka. After 11.6 ka, hydroclimate shifts inferred from ostracod species changes (Eucypris mareotica and L. inopinata) and their δ18O values were as follows: (1) 11.6–7.4 ka—larger, but still small lake area with greater moisture availability under primarily dry climate conditions, (2) 7.4 to 3.2 ka—increasing lake level under a warmer and wetter climate, and (3) 3.2 ka to present—stable, large, brackish lake. The low ratio of lake water volume to runoff, and close proximity of the core site to freshwater input from the river mouth would have resulted in relatively lower ostracod δ18O values when Lake Qinghai was small in area during the interval from 32.0 to 15.0 ka. Lower ostracod δ18O values during interstadials and throughout the entire Last Glacial Maximum and early deglacial (ca. 24.0–16.0 ka) were caused by a greater contribution of seasonal meltwater from ice or snow and low incoming precipitation δ18O values related to cold climate conditions in the region at that time. 相似文献
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This paper investigates the correlations between lake level change, rainfall variability and general atmospheric forcing in
southern Africa. The analysis of fossil diatom assemblages in a sediment sequence from the small, rain-fed Lake Nhaucati,
southern Mozambique, is presented and discussed in relation to regional palaeoclimate data. The accumulation of organic sediments
in Lake Nhaucati began 1,600 years ago when the lake level was rising. Lithology and pollen suggest a low stand at 800 AD,
which correlates with other climate proxies from the summer rainfall region of southern Africa. The diatom assemblage suggests
that lake levels were high between 900 and 1300 AD, with shorter low stands at c.1100 and 1200 AD. The period after 1400 AD
was marked by a slow rate of accumulation and consequently a low temporal resolution. The correlation with other climate proxies
in the summer rainfall region, written sources, and pollen data suggests repeated droughts corresponding to the Little Ice
Age, though the driest periods may have caused complete desiccation of the lake. Higher lake levels are suggested after 1800 AD,
though written sources suggest droughts in the beginning of the twentieth century. The analysis shows a good correlation with
palaeoclimate data from the summer rainfall region and confirms the presence of an anti-phase relationship between the summer
rainfall region of southern Africa and the bi-modal rainfall region of east tropical Africa. It also supports the general
hypothesis that variation in the intensity of the Inter Tropical Convergence Zone is the main agent modulating rainfall over
southern and eastern Africa on centennial timescales. 相似文献
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《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3-4):165-174
The behaviour of the ice-dammed lake, Strupvatnet, Troms County, Norway, is described. Past observations are noted and related to observations in 1959 and to other ice-dammed lakes. Mechanisms for opening and maintaining water flow during a ‘hlaup’ are discussed. It is considered that Liestol's melt widening process operates after initiation by a pressure gradient across the dam. The lake and the internal drainage system of the glacier are thus linked. There is no evidence of lifting of the ice dam at Strupbreen. 相似文献
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Post-isolation (9,600 year BP) sedimentology in Lake Pyhäjärvi, Finland, was studied using sub-bottom echo-sounding and sediment coring. The sediment sequence appeared in the echo-sounding profiles as two sections: (1) a lower section of homogenous, light grey gyttja clays, and (2) an upper section with dark layers of mainly clay gyttjas and gyttjas, here referred to as C_gyttja. We investigated the thickness and volume of sediments as well as their morphology and areas of accumulation. Approximately 77 % of the lake represents areas of accumulation, containing 34 and 1.3 million tons of dry matter and carbon, respectively. Spatial variability in sedimentological properties indicates that accumulation in the Kirkkoselkä sub-basin was focused into the deepest areas since lake isolation. In the Isoselkä sub-basin, however, accumulation was focused partially onto the flanks of the depression, whereas the deepest parts (23–27 m) of the sub-basin represent erosional areas. There appears to have also been sediment re-suspension and re-deposition, as indicated by erosion surfaces. This, combined with dune-like bottom morphology in the accumulation areas, provides evidence for the role of wind-driven bottom currents on sedimentation dynamics in the Isoselkä sub-basin. Increases in Cu and Zn concentrations, driven by Pyhäsalmi mining activities, were used as a geochemical marker for recent sedimentation (RS) between 1966 and 2008. As a consequence of wind-driven bottom currents, 60 % of the metals accumulated in the Kirkkoselkä sub-basin and 40 % accumulated in the Isoselkä sub-basin. There is a spatial correlation between amounts of C_gyttja and RS. In the middle of dune-like C_gyttja formations in the Isoselkä sub-basin, the RS grain size is smaller than in other areas. Variations in RS are greatest along the borders of the accumulation area, likely a consequence of bottom currents in those areas. 相似文献
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Lakes in China have undergone considerable environmental changes during the past 50 years, e.g. lake level, water area changes, as did in the past several thousands years. The enhanced human activities, such as land reclamation, application of chemical fertilizer, land use and cover, irrigation and industrialization in the catchment etc., have played an important role on the recent decades＇ changes of these lakes, although constrained to a great extent by the natural impact. Comparative study on variations of lake volume （water level, depth and area） in the eastern and western lake regions of China during 1950-2000 indicated that, lake volume in the eastern region had approximately undergone a two-stage change, i.e. a dramatic decrease from the 1950s to 1970s, and a continuous increase between the 1980s and 1990s; while, in the western region, lake volume had been decreasing nearly all the time. Further studies on some typical lakes concluded that, climatic change was a primary factor for the variations of lake volume during the past 50 years, although human activities showed important effect. 相似文献
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Melissa L. Chipman Gina H. Clarke Benjamin F. Clegg Irene Gregory-Eaves Feng Sheng Hu 《Journal of Paleolimnology》2009,41(1):57-75
We analyzed sediments of the past 2000 years from Ongoke Lake, southwest Alaska, for organic carbon, organic nitrogen, biogenic
silica (BSi), and diatom assemblages at decadal to centennial resolution to infer limnological changes that may be related
to climatic variation in southwestern Alaska. The chronology is based on a 210Pb profile from bulk sediments and nine AMS 14C ages from terrestrial plant macrofossils. Four of the 14C ages span a core depth interval of 60.5 cm but are statistically indistinguishable from one another with a mean of ~1300
AD, which compromises the determination of temporal trends at Ongoke Lake and comparison with other paleoclimate records.
The diatom record suggests changes in the duration of ice cover and strength of thermal stratification that are probably related
to temperature variation. This variation includes a cold interval around the first millennium cooling (FMC) and a warm interval
spanning the medieval climate anomaly (MCA). However, the lake-sediment record shows no clear signals of temperature variation
for the period of the Little Ice Age (LIA) or the twentieth century. Climatic changes during these periods may have been manifested
through effective-moisture (precipitation minus evapotranspiration) variation in the Ongoke Lake area. We estimate water depths
and infer effective-moisture fluctuations by applying a regional transfer function to our diatom record. Together with inferences
from diatom autecologies, this water-depth reconstruction suggests that effective moisture increased steadily from 50 BC to
350 AD, which was followed by relatively dry conditions between 550 and 750 AD and relatively wet conditions between 750 and
1450 AD. Effective moisture was low from ~1450 to 1850 AD, coinciding with the LIA; an alternative age model places this interval
between ~1315 and 1850 AD. During the past 150 years, effective moisture increased, with estimated water depths reaching peak
values in the second half of the twentieth century. This study offers the first paleolimnological record for inferring centennial-scale
climatic variation over the past two millennia from southwestern Alaska.
相似文献
| Feng Sheng HuEmail: |
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Lakes in China have undergone considerable environmental changes during the past 50 years, e.g. lake level, water area changes, as did in the past several thousands years. The enhanced human activities, such as land reclamation, application of chemical fertilizer, land use and cover, irrigation and industrialization in the catchment etc., have played an im-portant role on the recent decades’ changes of these lakes, although constrained to a great extent by the natural impact. Comparative study on variations of lake volume (water level, depth and area) in the eastern and western lake regions of China during 1950–2000 indicated that, lake volume in the eastern region had approximately undergone a two-stage change, i.e. a dramatic decrease from the 1950s to 1970s, and a continuous increase between the 1980s and 1990s; while, in the western region, lake volume had been decreasing nearly all the time. Further studies on some typical lakes concluded that, climatic change was a primary factor for the variations of lake volume during the past 50 years, although human activities showed important effect. 相似文献
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In arid regions of Central Asia, cyclicity in the humidification behavior of a region shows long-term trends of changes in the water levels of closed lakes. Thus, the last 10 years saw a decrease in the water level by several meters on one of the region’s largest lakes — Hulun Nur (PRC). For water level stabilization on the PRC’s territory, a package of measures is undertaken for a partial Hailar river flow transfer (in the upper reaches of the Argun’ river) to Lake Hulun Nur. It is obvious that the lake’s water level regime will experience substantial changes. This paper discusses a variety of consequences of the river flow transfer and different water management modes, and forecasts the lake’s possible level regime, the Argun’ river discharge and the ecological consequences of measures of this kind for the Russian part of the drainage basin. 相似文献
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Karin Holmgren Jan Risberg Johan Freudendahl Mussa Achimo Anneli Ekblom Joao Mugabe Elin Norstr?m Sandra Sitoe 《Journal of Paleolimnology》2012,48(2):311-322
Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300?years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300?years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC?CAD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150?C1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed. 相似文献
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The distribution of solution lakes on gypsum evaporites isconsidered. Details are given of Lake Inva^rtita (Nucs¸oara), aRomanian lake of this type, in the Arges¸ district. 相似文献
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1 IntroductionPopulation growth and economic development aggrandizes day by day pressure on land resources, which results in serious land degradation and environmental pollution[1]. The status and management of land resources has become one of the highlights of global soil study[2]. Human-induced soil changes and their effects on human lives and eco-environments have received extensive attention[3-7]. Improving soil quality is one of the most important factors for sustaining the global biosphe… 相似文献
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Fossil Trichoptera (caddisfly) remains have been identified and quantitatively recorded in the late-glacial and early-Holocene sediments from Kråkenes Lake, western Norway. The sediment sequence was deposited between 12,300 and 8850 14C BP, covering the Allerød, Younger Dryas, and early-Holocene periods. The first Trichoptera were recorded at 12,000 14C BP, and during the Allerod a diverse assemblage of Limnephilidae taxa developed in the lake. By about 11,400 14C BP the relatively thermophilous Polycentropus flavomaculatus and Limnephilus rhombicus were present, suggesting that the summer water temperature was at least 17 °C. This temperature fell by 5-8 °C at the start of the Younger Dryas, and the thermophilous taxa were replaced within 20-40 14C yrs by Apatania spp., including the arctic-alpine A. zonella, suggesting a maximum summer water temperature of 10-12 °C. The Trichoptera assemblage was impoverished in numbers and in diversity over the next 200 yrs as the severe conditions of the Younger Dryas developed. As soon as temperatures rose and glacial meltwater and silt input ended about 700 14C yrs later, the resident Apatania assemblage expanded immediately, within 10 yrs. About 130 yrs later, thermophilous taxa replaced Apatania, and a much more diverse assemblage than in the Allerod occupied the varied habitats made available by the development of the Holocene lake ecosystem. The 130 yr delay may have been caused by a gradual temperature increase crossing a critical threshold, or by the time taken for thermophilous taxa to migrate from their Younger Dryas refugia. 相似文献