Quantitative reconstruction of the paleosalinity at Qinghai Lake in the past 900 years

Based on the function relationship between the shell length of Limnocythere inopinata and the salinity of its living water in Tibetan Plateau lakes, the paleosalinty of Qinghai Lake in the past 900 years was reconstructed through the measurement of the adult body length of Limnocythere inopinata. Meanwhile, the paleosalinity sequence of Qinghai Lake during the same period was rebuilt by the St/Ca ratio of the shell of Eucypris inflata combined with the St/Ca ratio of living ostracod valves from the species of genus Eucypris inflata and the host water. The paleosalinity results obtained by two different methods were compared and assessed in this paper. To check the result, it was also contrasted with other historical climatic sequences of this area including tree ring and ice core. It was shown that the paleosalinity sequence rebuilt by adult ostracod body length had high reliability, and the paleosalinity reconstruction method by trace elements of ostracod shells was not suitable for Qinghai Lake. From the reconstructed paleosalinty sequence of Qinghai Lake, it can be found that low salinity during 1160-1290 AD showed the humid climate condition on the Mediaeval Warm Period in this area, while the high salinity during 1410-1540 AD, 1610-1670 AD and 1770-1850 AD which was corresponding to the three cold pulses of the Little Ice Age with a dry climate condition. And the high salinity in the latest several decades was consistent with recent warm and dry trends of the climate in this area. The good consistency of the reconstructed palaeosalinity sequence and the precipitation sequence in this area rebuilt by tree ring proves the reconstruction of past lake salinity is reliable.     

A carbon－and oxygen－isotoperecord of recent environ－mental change from Qinghai Lake, NE Tibetan Plateau

A c. 300-year oxygen and carbon isotope record derived from fine-grained and ostracod carbonate from Qinghai Lake testifies to dramatic interannual to illterde-cadal linmologicai change. Fine-grained carbonates, whichare mainly authigenic, are likely to have formed in the epillmnion of the lake and their isotopic composition reflects the summer temperature and, more importantly, the isotopic composition of the near-surface waters, which is mainly afunction of evapor ative concentration. Ostracod shells aresecreted in the benthos of the lake, and their isotopic compo-sition reflects summer bottom-water conditions, together with fractionation effects, which may differ between species.Differences between contemporaneous values from authi-genic carbonates and ostracod shells may provide an indica-tion of stratification within the lake and variations in effec-tive precip itation over the northeast part of the Tibetan Pla-tcau over the past 300 years. A period of moderate evapora-tive concentration, from about 300 to 100 yr BP, was inter-rupted by a marked wet phase from-100 to 40 vr BP. which was in turn followed by a return to drier conditions in the most recent part of the record. The increase in δ^18O values in the latter part of the record accords well with instrumental records of lake-level lowering and salinity increase since about 1955 AD.     

Carbonate verse silicate Sr isotope in lake sediments and its response to Little Ice Age

The ^87Sr/^86Sr ratios of silicate (acid-insoluble,AI,) and carbonate (acid-soluble,AS) of the lake sediments from the Daihai Lake ,Inner Mongolia since the last 500 years are measured respectively ,indicationg that chemical weathering of silicate minerals was in an early stage since the Little Ice Age within the Daihai watershed by combination with mineral constitute,Rb/Sr ratio and CaCO3 content in the sediments,During the Little Ice Age maximum,an evident peak in the ^87 Sr/^86Sr ratios of both silicate and carbonate in sediments suggests that a cold climate condition is unfavorable to dissolving radiogenic stontium from silcate minerals ,Meanwhile,the variation of ^87 Sr/^86Sr ratios of silicate and carbonate also reflects a projected warming climate favorable to intensifying chemical weathering after the Little Ice Age ,Consequently,the ^87 Sr/^86Sr ratio of both silicate and carbonate in inland lake sediment can be used as an effective proxy of the past climate in single watershed.     

东洞庭湖介形类现生种的定量生态信息

以东洞庭湖介形类现生种为研究对象,对其进行野外生态调查,获取该生物定量生态信息,以此为该湖水体污染程度监测与评价奠定必要基础,同时丰富我国介形类现生种生境数据.本研究共发现东洞庭湖介形类现生种4属4种,它们为比利时舍氏玻璃介(相似种) Schellencandona cf. belgica、豆形豆形玻璃介Fabaefo...     

青藏高原通天河盆地五道梁组介形虫壳体Mg/Ca和Sr/Ca地球化学特征及古环境意义

中新世早期青藏高原腹地曾经发育了面积巨大的古大湖,此时恰逢青藏高原的快速隆升关键时期.为研究高原腹地在此期间环境的演化,对五道梁组中介形虫壳体的Mg/Ca 和Sr/Ca的值进行了测试.通天河盆地五道梁组地层中的介形虫壳体的Mg/Ca 和Sr/Ca数值的特征,结合剖面岩性特征,反映了23.8～21.8 Ma前该湖泊区域气候由湿润-干旱-暖湿的演化趋势.其气候的变化可能是此时期青藏高原从快速隆升到剥蚀夷平后高原北部构造隆升活动的结果.该研究为进一步了解青藏高原腹地的古环境探索了一条新的途径.     

Pollen assemblage characteristics of lakes in the monsoon fringe area of China

This paper presents the pollen assemblages from 108 surface sediment samples from 4 lakes （the Lake Daihai, Lake Hongjiannao, Lake Hulunnao and Lake Duikounao） in the monsoon fringe area of China. The herb pollen taxa Artemisia, Chenopodiaceae, Poaceae and Compositae are the major components of pollen assemblages of the 4 lakes and Pinus, Betula, Quercus, Ulmus, Populus, Ostryopsis and Elaeagnaceae are frequently presented, which reflect regional and local vegetation well. The mean similarity coefficients for samples from the Lake Daihai, Lake Hongjiannao, Lake Hulunnao and Lake Duikounao are 0.66±0.17, 0.71±0.11,0.73±0.12 and 0.67±0.12 respectively, so pollen assemblages are relatively consistent in each lake, which shows that focusing and mixing effects have occurred before and after pollen deposition. However, pollen assemblages do differ between sampling sites in each lake. The largest difference is seen in the Lake Daihai, followed by the Lake Duikounao, Lake Hulunnao and Lake Hongjiannao （The mean Euclidean distance is 20.09 ± 11.11, 11.22 ± 3.64, 10.67 ± 4.03 and 8.44 ± 4.51 respectively）. These differences are possibly caused by the differences of focusing and mixing effects, pollen source areas, drainage areas and regional vegetation compositions. The Lake Daihai and Lake Hongjiannao have water deeper than 5 m and strong re-suspension, focusing and mixing effects occur in the lakeshore and shallow water areas, where pollen concentrations are lower than in deeper lake areas. In the Lake Hulunnao and Lake Duikounao, with depths less than 5 m, re-suspension and mixing effects are obvious across the whole lake area, so pollen assemblages and pollen concentrations are more consistent among sampling sites in each lake. Comparison between the lake samples and samples from the inflowing river reveals that wind is primary pollen transportation force in the Lake Hongjiannao, where the consistency of pollen assemblage is conspicuous, while there is greater variation in lakes where pollen input is do     

Speleothem Mg,Sr and Ba records during the MIS 5c-d,and implications for paleoclimate change in NE Sichuan,Central China

Trace metals of Mg, Sr and Ba in a stalagmite (SZ2) collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results indicate that the Mg/Ca, Sr/Ca and Ba/Ca ratios of SZ2 varied between (9500-14700) 10 6 , (54-123) 10 6 and (31-82) 10 6 , respectively. The three records displayed significant millennial scale variations, which correlate with changes in past climate and environment. Lower values of Mg/Ca ratios and higher values of Sr/Ca and Ba/Ca ratios of SZ2 occurred during relatively cold-dry marine isotope stage (MIS) 5d, while the opposite trend was observed during relatively warm-humid MIS 5c. Trace metals in speleothems can be affected by distribution coefficients or trace metal concentrations in solutions from which speleothems precipitate. Temperature is suggested to be the dominant controller of Mg/Ca ratios in SZ2, whereas the Sr/Ca and Ba/Ca ratios may have been influenced by surface soil and atmospheric dust activities and prior calcite precipitation in Suozi Cave. Further investigations are warranted as to whether Sr/Ca and Ba/Ca ratios were affected by temperature and growth rate of the speleothem. The shifts of Mg/Ca, Sr/Ca and Ba/Ca records in SZ2 during the transition from MIS 5d to 5c apparently were earlier than the oxygen isotope record ( 18 O) of the same stalagmite. This possibly indicates (1) that atmospheric dust activity (the mechanism affecting SZ2 Sr/Ca and Ba/Ca ratios) is closely related to temperature, and (2) that temperature changes (dominated by solar insolation) precedes change in speleothem 18 O records which are controlled by both summer monsoons and winter temperatures.     

A carbon- and oxygen-isotope record of recent environ- mental change from Qinghai Lake, NE Tibetan Plateau

An understanding of natural climatic variability is essential for evaluating anthropogenic impacts on recent and future climate[1—3]. Due to the lack of lengthy instrumental records, such an understanding must be gained from natural archives of climate change. Palaeolimnological indicators of past lake levels may provide a sensitive record of changes in effective precipitation in closed basins. This approach is particularly relevant on the Tibetan Plateau, where instrumental records are very…     

Effect of Ca on CO2 corrosion properties of X65 pipeline steel

The effect of Ca²⁺ on CO₂ corrosion to X65 pipeline steel was investigated in the simulated stratum water of an oil field containing different concentrations of Ca²⁺. It is found that Ca²⁺ can enhance the corrosion rate, especially in the Ca²⁺ concentration from 256 to 512 mg/L, which can be attributed to the growing grain size and loosing structure of corrosion scales with increasing Ca²⁺ concentration. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) investigations reveal that a complex carbonate (Fe, Ca)CO₃ forms at high Ca²⁺ concentration due to the gradual replacement of Fe²⁺ in FeCO₃ by Ca²⁺.     

Molecular organic geochemical evidence for paleoenvironmental changes at 11.87–12.28 m in GS-1 sedimentary core, Gucheng Lake, East China

Organic lipids with different occurrence modes in a sedimentary core in a subtropical freshwater lake, Gucheng Lake, were sequentially extracted, separated and analyzed. The down-core variations of OEP index of alkanes, C_18:2/C_18:0 ratios of fatty acids, ratios of bound, fatty acids to free fatty acids, thermo-maturity indices of hopanoid hydrocarbons and rerative concentrations of sedimentary minerals revealed an evident increasing in allochthonous input from rock detritus below 12.28 m in the sedimentary profile. The distribution pattern of tightlybound β-hydroxy fatty acids indicated a difference in bacterial communities above and below the boundary, as well as the gammacerane index may assign a significant change in lake water salinity. The evidence, in general, suggested that a significant paleoenvironmental change had taken place in ca. 9.6 kaBP on the regional basis.     

近300年来岱海流域气候干湿变化与人类活动的湖泊响应

根据岱海60cm柱状岩芯的磁化率、孢粉、粒度等环境指标的分析结果,对历史时期岱海气候干湿变化和人类活动的湖泊记录进行探讨,岱海湖泊沉积记录近300年来的气候干湿变化可划分七个阶段,与历史记载有较好的一致性;频率磁化率高值段对应气候偏湿阶段,低值对应气候偏干阶段,人类活动特别是人口增加和土地开垦,加剧流域水土流失,导致湖泊沉积物中细颗粒组分增加,频率磁化率升高;孢粉Ulmus的变化受流域人口增加的影响。频率磁化率和孢粉是反映岱海历史时期干湿变化和人类活动的重要环境指标。     

The Sr, Nd isotopic composition of lamprophyres in Laowangzhai gold orefield, Yunnan Province

Lamprophyres are widely spread over the Laowangzhai gold orefield in northern Mt. Ailao structure zone, Yunnan Province. Lamprophyres in the orefield are temporally and spatially related to gold mineralization. Lamprophyres in the orefield have anomalous Sr and Nd isotopic compositions, e.g. the 87Sr/ 86Sr ratios (0.706 665-0.707 960, the 87Sr/ 86Sr ratio of sample YLW-44 is 0.709 041) are higher than the modern value of the original mantle (0.704 5), the 143Nd/ 144Nd ratios (0.512 463-0.512 551) are lower than the modern value of the original mantle (0.512 638), and the calculated values ε Sr>0 (28.1-63.7) and ε Nd<0 (-1.34--3.07). The results of investigation indicate that lamprophyres in the Laowangzhai gold orefield with anomalous Sr and Nd isotopic compositions would not be produced as a result of contamination of the primary magma with the isotopic features of MORB by the crust materials high 87Sr/ 86Sr ratios and low 143Nd/ 144Nd ratios in the processes of rising or in the magma chamber, but the result of metasomatism of source mantle.     

Oxygen isotope variation in the water cycle of the Yamzho lake Basin in southern Tibetan Plateau

Given the potential use of stable isotope in the paleoclimate reconstruction from lacustrine records as well as in the local hydrology cycle, it is crucial to understand the processes of stable isotope evolution in catchment in the Tibetan Plateau region. Here we present a detailed study on the water oxygen isotope based on 2 years observation including precipitation, river water and lake water in the Yamzho Lake, south of the Tibetan Plateau. Temporal variation of local precipitation 5180 shows an apparent ＂monsoon cycle＂. In monsoon season, 5180 in waters is lower. In non-monsoon season, δ^18O in precipitation and lake water is higher and higher river δ^18O exists in spring, probably reflecting the effect of land surface evaporation, together with the higher δ^18O values in spring precipitation. It is also found that the surface lake water δ^18O varies seasonally and annually. The lower lake water δ^18O in the late summer is apparently related to the summer monsoon precipitation. The mean δ^18O value of lake water in 2007 is 1.2‰ higher than that in 2004, probably due to the less monsoon precipitation in summer of 2007, as can be confirmed from the precipitation data at the Langkazi meteorological data. It is also found that an obvious shift of vertical lake water δ^18O reflects the fast mixture of lake water. δ^18O values of lake water are over 10‰ higher than those of precipitation and river water in this region due to the evaporation fractionation. The modeled results show that the evaporation process of the lake water is sensitive to relative humidity, and the present lake water δ^18O reflects a relative humidity of 51% in the Yamzho Lake. It shows that the lake will take 30.5 years to reach present lake water δ^18O given a large shift in the input water δ^18O. The modeled results also reveal that surface lake water temperature and inflow δ^18O have slight effect on the isotopic balance process of lake water in the Yamzho Lake.     

Estimation of the rational wa-ter area for controlling wind erosion in the dried-up basin of the Ebinur Lake and its effect detection

The Ebinur Lake region was described as a “Green Labyrinth” in “Xinjiang Map Records: Records of Rivers” published in 1910, however, the ecology and environment in the region have been seriously degenerated due to the impacts of human activities during the recent 40 years. A dried-up lake basin with an area of 107.4 km² forms in its northwestern part, is covered by unconsolidated silt deposit without vegetation, and has become one of the main dust sources of dust weathers in north Xinjiang, and the dust with an annual amount of 4.8×10⁶ t is blown out of the region by strong winds from the Alataw mountain-gap where there are 164 days occurring strong winds in a year. The rational water area and inflow of the Ebinur Lake for improving the ecology in the lake region and effectively controlling wind erosion in the dried-up lake basin are estimated using the water balance equation after analyzing the current ecological problems and the relationship be-tween the granular composition of deposit in the dried-up lake basin and the dust weathers, and the ecological effects in recent years are monitored. It is considered that the water area of the Ebinur Lake for improving the ecology in the lake region and effec-tively controlling wind erosion in the dried-up lake basin should be 800 km² at least, and the annual volume of surface runoff and groundwater recharging the lake should be over 7.92×10⁸ m³.     

Formation mechanisms of megadunes and lakes in the Badain Jaran Desert, Inner Mongolia

Field observations demonstrate that calc-sinters occurred in the lakes of Badain Jaran Desert. 87Sr/86Sr ratios,14C,δ 13C and mineral com-positions of calc-sinters,and 3He/4He,4He/20Ne,δ 18O,δ D,pH and TDS of water from springs and lakes are analyzed in detail. The results indicate that the lake water is supplied through deep fault zone. The “ker-nel” of stabilized dunes in the Badain Jaran Desert perhaps consists of calc-sinters and calcareous ce-mentation layers. Deep-seated groundwater effuses from this “kernel” and recharges to lakes in desert. Precipitation and snowmelt water from the Qing-hai-Tibet Plateau is fed into the Badain Jaran Desert,Gurinai,Wentougaole and Ejinqi areas through the Xigaze-Langshan Fault zone. The isotopic composi-tions of groundwater in the Alax Plateau are abnor-mal due to the strong evaporation of the Gyaring and Ngoring lake water in the headstream of the Yellow River. Groundwater dissolves dissoluble fractions of rocks during its transportation through the fault zone and flows out of the mouth of spring in the Badan Jaran Desert. The dissoluble fractions are finally de-veloped into calc-sinters and calcareous cementation layers around the spring. Calci-sinters are gradually largened and eventually emerge on the surface of lake water. Eolian sands accumulate on the surfaces of calc-sinters and calcareous cementation layers,and eventually develop into dunes. Invasion of magma causes an increase in the temperature of groundwater within the faults. Groundwater evapora-tion provides water vapor for the formation of humid stabilized dunes during its upwelling. Rhizoconcre-tions found in Yihejigede indicate that the dune was formed and remained immovable 4700 years ago. The height of the megadunes is proportional to thermal quantity carried by the groundwater.     

Water balance estimates of ten greatest lakes in China using ICESat and Landsat data

Lake level and area variations are sensitive to regional climate changes and can be used to indirectly estimate water balances of lakes. In this study, 10 of the largest lakes in China, ～1000 km² or larger, are examined to determine changes in lake level and area derived respectively from ICESat and Landsat data recorded between 2003 and 2009. The time series of lake level and area of Selin Co, Nam Co, and Qinghai Lake in the Tibetan Plateau (TP) and Xingkai Lake in northeastern China exhibit an increasing trend, with Selin Co showing the fastest rise in lake level (0.69 m/a), area (32.59 km²/a), and volume (1.25 km³/a) among the 10 examined lakes. Bosten and Hulun lakes in the arid and semiarid region of northern China show a decline in both lake level and area, with Bosten Lake showing the largest decrease in lake level (?0.43 m/a) and Hulun Lake showing the largest area shrinkage (?35.56 km²/a). However, Dongting, Poyang, Taihu, and Hongze lakes in the mid-lower reaches of the Yangtze River basin present seasonal variability without any apparent tendencies. The lake level and area show strong correlations for Selin Co, Nam Co, Qinghai, Poyang, Hulun, and Bosten lakes (R ² >0.80) and for Taihu, Hongze, and Xingkai lakes (～0.70) and weak correlation for East Dongting Lake (0.37). The lake level changes and water volume changes are in very good agreement for all lakes (R ² > 0.98). Water balances of the 10 lakes are derived on the basis of both lake level and area changes, with Selin Co, Nam Co, Qinghai, and Xingkai lakes showing positive water budgets of 9.08, 4.07, 2.88, and 1.09 km³, respectively. Bosten and Hulun lakes show negative budgets of ?3.01 and ?4.73 km³, respectively, and the four lakes along the Yangtze River show no obvious variations. Possible explanations for the lake level and area changes in these four lakes are also discussed. This study suggests that satellite remote sensing could serve as a fast and effective tool for estimating lake water balance.     

广西里湖地下河水化学特征及其影响因素

【目的】岩溶地下水由于储量相对丰富,水质优良,是良好的供水水源。因此,揭示岩溶地下水水化学特征及其影响因素,能够为保护和利用岩溶地下水提供科学依据。【方法】以广西里湖地下河为研究对象,于不同季节对里湖地下河上游到下游的河水进行水化学分析。【结果】里湖地下河水主要阴离子为HCO-3,主要阳离子为Ca2+,水化学类型为HCO3-Ca型,影响水质变化的主要离子为Cl-,NO-3,SO2-4;各离子浓度从上游到下游变化不一致,总体呈现先升高再降低的趋势,季节变化体现在雨季离子浓度偏低,旱季偏高。【结论】地下水地球化学组成受控于碳酸盐岩的自然风化溶解;污染物质主要来源于人类活动的输入,降雨的稀释作用是影响水质季节性变化的主要原因,地下河自身存在的自净能力使得污染物浓度降低,尤其是甘田坝到小龙洞洞穴伏流段水体中部分污染物的浓度显著降低。     

The binding of the anticoagulation factor Ⅰ from the venom of Agkistrodon acutus to activated factor Ⅹ

Anticoagulation factor Ⅰ (ACF Ⅰ) from the venom of Agkistrodon acutus prolonged plasma prothrombin time (PPT) with dose-dependent manner and exhibited marked anticoagulant activity only at the concentration higher than its critical concentration (12 nmol/L). It was discovered that ACFⅠ formed a 1:1 complex with activated coagulation factor (FⅩa) in the presence of Ca2+ ions by the method of polyacrylamide gel electrophoresis. Both native ACFⅠ and decalcified ACFⅠ failed to form complexes with FⅩa in the absence of Ca2+. Sr2+ ions were able to replace Ca2+ ions in the binding of ACFⅠ to FⅩa, but both Ba2+ ions and Tb3+ ions were ineffective. ACFⅠ was a new member of the Ⅸ/Ⅹ-bp family in the C-type lectin superfamily, and had a amino acid composition similar to the other members of this family. It was composed of 251 amino acid residues with a molecular weight of 29 603.6 u on non-reducing condition, determined by MALDI-TOF-MS, and a molecular weight of 14.7 ku on reducing condition, determined by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).     

砗磲高分辨率Sr/Ca温度计:3种物种的对比分析

对采自南海西沙的3种不同种的现代砗磲(库氏砗磲、鳞砗磲、砗蚝)进行了高分辨率Sr/Ca比值分析.结果表明:库氏砗磲和鳞砗磲的Sr/Ca比值呈现出年周期变化并与实测的海表面温度(SST)形成较好的对应;而砗蚝的Sr/Ca比值年周期信号较弱且与温度的对应存在较大的不确定性.通过全年逐月或逐周对应和极端对应,我们共获得了两种砗磲的4个有效的Sr/Ca-SST方程,并能较好地作为Sr/Ca温度计进行温度恢复.对比不同种类的砗磲,其Sr/Ca分布有所不同,相应的Sr/Ca-SST方程也有一定的区别.这项研究为选择性地应用砗磲研究全新世气候变化提供了依据.     

西藏昂仁湖全新世湖相纹层介形类

西藏昂仁全新世湖相沉积纹层发育,其中分析出介形类4属5种,即为Leucocytherella trinoda、L.sinensis、Eucypris gyirongensis、Candona gyirongensis及Ilyocypris biplicata;介形类在纹层中呈现规律性变化,即深色层与浅色层介形类属种组成一致,定量数据揭示浅色层总丰度均大于深色层。根据介形类生态特征推测,浅色层代表盐度较高的年份沉积。