西藏玛旁雍错和拉昂错水深、水质特征及现代沉积速率

基于2009年和2010年分别在玛旁雍错和拉昂错开展的2次野外湖泊调查,本文简要报道这2个藏南内流水系湖泊的水深分布、湖水理化特征及湖泊现代沉积速率.测深结果显示玛旁雍错湖盆形状规则,深水区坡度平缓,最大水深为72.6 m;拉昂错北部为较浅的河流冲积扇,通过狭长的水道与开阔的南部湖区相连,南部湖区中心平坦,实测最深处49.03 m;根据水深数据计算的玛旁雍错和拉昂错水量分别为1.462×10¹⁰m³和5.711×10⁹m³.玛旁雍错湖水剖面水质在垂直方向上呈现明显的分层结构,温跃层介于25~35 m之间,温度梯度为0.17℃/m,水体pH、电导率和溶解氧在温跃层具有同步变化特征;拉昂错湖水温跃层与玛旁雍错相比不明显,5~15 m间温度梯度为0.16℃/m,湖水pH与溶解氧呈反相变化,这可能与水生植物呼吸作用有关.2个湖泊湖水的主要离子组成特征除Ca²⁺外基本相同,拉昂错主要离子浓度约为玛旁雍错的3倍,而Ca²⁺则约为玛旁雍错的1/2;利用²¹⁰Pb和¹³⁷Cs方法对玛旁雍错和拉昂错的短岩芯进行了测试,结果表明2个湖泊近代沉积速率分别约为0.31 mm/a和0.65 mm/a.     

NCEP/NCAR再分析资料在纳木错流域湖泊/冰川区适用性分析

利用中国科学院青藏高原研究所纳木错多圈层综合观测研究站在念青唐古拉峰扎当冰川垭口(30.47°N、90.65°E,5800m)和纳木错站(30.77°N、90.99°E,4730m)的逐日平均气温、相对湿度、气压等资料,与同期NCEP/NCAR再分析资料进行了对比分析,讨论了再分析资料在纳木错流域湖泊/冰川区气候变化研究中的适用性.结果表明:扎当冰川垭口和纳木错站气压再分析资料的可信度好于气温,相对湿度稍差:扎当冰川垭口气压和相对湿度再分析值与实测值的差值在冬季偏大,夏季偏小,气温则相反.在研究期间,总体上再分析资料在冰川区的可信度好于湖泊区,再分析资料能很好地反映该地区地面气压、气温和相对湿度的日变化特征,在应用到该地区气候变化的研究时应考虑地形的影响.     

1950年以来青藏高原兹格塘错碳酸盐稳定碳同位素变化及其原因

兹格塘错是青藏高原中部一个典型的半混合型咸水湖泊。本文在~(210)Pb和~(137)Cs定年的基础上,研究了兹格塘错重力岩芯(ZGTC A-1)小于38.5μm细颗粒组分碳酸盐稳定碳同位素1950年以来的变化及其影响因素。对冬夏季湖水水化学特征的分析表明,夏季湖水溶解CO_2呈逸出状态,冬季湖水钙离子浓度是夏季湖水的10倍,据此可以得出兹格塘错碳酸盐矿物主要在夏季沉淀。通过与那曲气象站气象记录对比发现,1950年以来A-1岩芯碳酸盐碳同位素变化与年均温度有很好的相关性,表现出年均温度高时碳同位素偏重,而年均温度低时碳同位素偏轻的特征。兹格塘错1950年以来自生碳酸盐碳同位素的变化是由湖区及水体碳循环(如碳酸盐沉淀,有机质的沉淀与分解,有机碳和无机碳的转化等)的变化引起的,但各种因素的相互作用非常复杂。碳酸盐含量也与温度有关,温度越高,碳酸盐含量越高,同时降水量与碳酸盐含量也存在明显的相关关系。1950年以来有机质含量与温度呈反相关,可能与湖泊生产力的下降有关。     

西藏普莫雍错不同岩芯环境指标的对比研究及其反映的近200年来环境变化

在西藏南部普莫雍错不同位置处采集了四支岩芯沉积物,对其中一支利用~(210)pb和~(137)Cs方法建立了沉积物的年代序列,并对其他三支岩芯的上部沉积物进行了总有机碳、无机碳、粒度及化学元素含量的分析.结合沉积物年代,对不同岩芯的环境代用指标进行对比,讨论了该地区近200年来的环境变化状况.结果表明,不同位置处采集的岩芯其环境指标变化趋势在整体上具有一定的可比性,但在细节变化与环境指标的数值上仍具有明显的差异,显示了湖泊内部沉积状况的空间差异性,这可能是由于采样点水深、水下地形以及与主要补给河流距离的不同而造成的.PY04岩芯环境指标显示普莫雍错湖区环境在约1900AD之前较为稳定;在约1900-1940AD之间湖区环境波动加剧,地表侵蚀增强,沉积速率加快;湖区环境在1940AD左右发生了明显的变化,温度显著升高,沉积物粒度增大,湖泊处于退缩状态,表明湖泊环境向暖干化方向发展.     

班戈错盐湖古湖岸堤石英光释光年代学及其古环境指示意义研究

古湖岸堤是湖泊湖面变化的地貌学证据,通过古湖岸堤沉积年代学研究可重建地质时期湖泊演化历史。青藏高原内陆湖泊众多,保存了大量的第四纪时期古湖岸堤,是研究过去湖泊演化和气候变化信息的重要载体。对青藏高原班戈错盐湖北岸和东岸的低位连续古湖岸堤开展了地貌调查和光释光年代学研究。结果表明班戈错自末次冰消期(13. 5±1. 2 ka BP)以来,湖面整体呈波动下降过程,期间出现了4期湖面稳定阶段,分别在末次冰消期(13. 5±1. 2～11. 2±1. 0 ka BP)、全新世早中期(10. 1±0. 8～6. 5±0. 5 ka BP)、全新世后期(4. 2±0. 4～3. 1±0. 2 ka BP)以及全新世晚期(1. 7±0. 1～1. 2±0. 1 ka BP)。全新世晚期约1. 7 ka BP以后湖面迅速退缩,湖泊蒸发浓缩进入盐湖阶段。在末次冰消期班戈错高湖面形成主要与北半球太阳辐射强度增加引起气温升高,导致区域冰雪融水量增加相关,而在全新世湖面变化主要受印度季风强度变化控制。     

Heavy metals and rare earth elements (REEs) in soil from the Nam Co Basin,Tibetan Plateau

Twenty-eight soil samples collected from the Nam Co Basin, Tibetan Plateau, have been analyzed for heavy metals (Cd, Cr, Ni, Cu, Zn, Pb and Mn), arsenic (As) and rare earth elements (REEs). In addition, for establishing the basic physio-chemical characteristics of the soil, pH, total organic concentration, electrical conductivity, and effective cation exchange capacity were measured. The results indicate that soil in the Nam Co Basin is still at an early alkaline weathering stage (pH = 7.94). Mean concentrations of heavy metals and As decreased as follows: Mn > Cr > Zn > Pb > Ni > Cu > As > Cd. The values of Cd, Cr, As, Pb and REEs in soil from the Nam Co Basin are higher relative to averaged background values over China. The chondrite-normalized diagrams of REEs suggest high REE(ΣLa → Eu)—enrichment, HREE(ΣGd → Lu)—depletion and Eu—depletion. Vertical profiles indicate that both heavy metals (except As) and REEs primarily exist in the surface soil. However, heavy metals and REEs vary in the surface soil between the southern and the northern bank of Nam Co. These differences are controlled mainly by parent materials.     

西藏格林错断层带的基本特征

格林错断层带是一条晚白垩纪以前形成,第四纪以来具明显活动性质的右旋走滑断层。断层带由4条次级走滑断层呈右行右阶羽列排列而成,在两条次级走滑断层的连接部位分别形成孜桂错、格林错、瓦昂错拉分区。格林错断层带是西藏中部地区的主要发震断层之一,全新世以来,至少有4期地震地表破裂沿该断层带发生。第四纪晚期,断层具明显的分段活动性质,并且断层活动有从北西向南东、向南迁移的迹象     

Assessment of soil metal distribution and environmental impact of mining in Katanga (Democratic Republic of Congo)

Metal and metalloid (As, Cd, Co, Cu, Pb and Zn) distribution in soils from the Katanga Copperbelt (Democratic Republic of Congo) is investigated in order to characterize the environmental impacts of mining and smelting activities in that area. The concentrations of Cu, Co, As, Zn, Pb and Cd in soils from mining sites are higher than in non-metalliferous sites and above permissible metal and metalloid concentrations in soils. Moreover, the fractionation and mobility of Co, and Cu in such environment is assessed using the application of both ammonium acetate-EDTA extraction and speciation modeling (WHAM 6). The resulting data set covers wide range of environmental conditions (pH, trace metals concentration, natural soils and soils affected by mining and ore processing). These extractions show that only a small fraction of Cu and Co is mobile, with variation depending on sites: mobility is higher in soils affected by mining and ore processing. The strong affinity of Mn-oxides for Co may explain lower Co mobility in Mn-rich soils. The high Mn and Fe contents of Cu–Co soils from Katanga may actually exert a protective effect against the toxic effects of Co. Finally, Cu–Co speciation modeling of contaminated sites emphasizes that organic matter strongly sorb Cu whereas Co speciation is mostly by Mn content. This type of study leads to a better understanding of metal fractionation and can guide to define different practices of phytoremediation.     

The Effects of Zn, Mn, and Co Accumulation on Growth and Chemical Composition of Fucus vesiculosus L under Different Temperature and Salinity Conditions

Abstract. Combined effects of temperature, salinity, and metal enrichment (Zn, Mn, Co) on the growth rate and chemical composition of Fucus vesiculosus L. were studied in culture. Factorial combinations of two temperatures and three salinities were used. The results indicated that the accumulation of Zn and Mn into algal tissue was enhanced by dilution of the media, whereas Co accumulation exhibited maxima at the medium salinity. Zn accumulation was enhanced by temperature, while the opposite was true for Mn and Co.
In the presence of metals the usual dilution-induced changes in growth activity and chemical composition of Fucus plants were altered, while responses to the temperature factor remained unchanged. In diluted media, growth activity and mannitol content decreased along with a simultaneous increase of protein content. In the presence of Zn and Mn the mannitol content exhibited peaks at the medium salinity; in the presence of Co the dilution-induced pattern remained unchanged. Salinity-induced changes in growth and protein content were altered in the presence of metals. Maxima in growth rates were found at the medium salinity. Growth was higher in extremely diluted media than in scawater, indicating an inversion of responses to the salinity factor. Both the growth rate and mannitol content were lowest under the influence of Zn.     

中太平洋富钴结壳Co元素地球化学特征

对在中太平洋研究区5座海山调查时获取的38个富钴结壳样品中主要金属元素的含量进行了化学分析,探讨了不同海山富钴结壳中Co元素含量的变化规律及结壳中元素间的相关关系,结果表明:(1)5座海山富钴结壳中的各主要金属元素含量相近,38个富钴结壳样品中Co元素的平均含量为0.67%,具有一定的开发前景。(2)不同海山富钴结壳中Co元素含量有一定变化,其变化与富钴结壳的类型、海水水深、地形地貌以及成矿作用等有密切的关系。Co元素在板状结壳中的含量为最高,在钴结核中的含量次之,而在砾状结壳中的含量为最低;富钴结壳中Co元素含量与海水水深呈负相关,浅水区富钴结壳中Co元素的含量明显高于深水区;海山地形地貌对Co元素的含量及富钴结壳的发育有一定影响,海山的椭圆状分支、支脉及边缘部分,Co元素的含量相对较高,富钴结壳发育得较好;Co元素富集成矿作用还主要受锰、铁水成成矿作用的控制。(3)富钴结壳中金属元素之间存在不同程度的相关性。Mn元素分别与Co、Ni、Cu、Zn、Mg、Na、Ba、Ti等元素呈强烈的正相关,而分别与Al、Si、Ca、P、Fe、Sr等元素呈负相关;Co元素分别与Cu、Al、P、Ca等元素呈负相关;Ca元素与P元素呈强烈正相关。