Stratigraphy of total metals in PIRLA sediment cores   总被引：1，自引：0，他引：1  

Stephen A. Norton  Ray W. Bienert Jr.  Michael W. Binford  Jeffrey S. Kahl 《Journal of Paleolimnology》1992,7(3):191-214

Sediment cores from 30 low-alkalinity lakes in northern New England (NE), New York (NY), the northern Great Lakes States (NGLS) of Minnesota, Michigan, and Wisconsin, and Florida (FL) have been dated by ²¹⁰Pb and analyzed for water and organic content, eight major elements (Al, Ti, Fe, Mn, Ca, Mg, Na, K) plus four trace metals (Pb, Zn, Cu, and V). Variations in the percentages of major elements through time are dominated by long-term independent variations in the abundance of SiO₂, FeO, and to a lesser extent Ca and Al. Additional variations are caused by varying proportions of inorganic matter. Major variations in chemistry are generally unrelated to documented distrubances in the watersheds; most disturbances are minor fires or selective logging.Accelerated accumulation of Pb from atmospheric sources into sediment first occurs in sediment dated between 1800 and 1850 in NY and NE, slightly later in the NGLS region, and about 1900 in FL. Modern accumulation rates in all areas are comparable (ca. 1 to 4 g cm^–2 yr^–1). Accumulation rates of Pb in some lakes have declined significantly from 1975 to 1985. Atmospheric deposition of anthropogenic Zn and Cu is also indicated by generally increasing accumulation rates in sediment cores, but the record is not as clear nor are chemical profiles in all lakes parallel to the trends in atmospheric emissions inferred on the basis of fossil fuel consumption, smelting, and other industrial activities. Inter-lake variations in profiles of Cu and Zn are large. Vanadium accumulation rates increase by the 1940s in NY and NE, but not until the 1950s in the NGLS region. This timing correlates with regional trends in the combustion of fuel oil, a major source of atmospheric V.Acidification of some of the lakes is suggested by decreases in the concentration and accumulation rates of Mn, Ca, and Zn in recent sediment, relative to other elements of catchment origin. The decreases generally occur slightly before the onset of acidification as indicated by diatoms. Increased sediment accumulation rates for Fe may indicate the acidification of watershed soils. The use of the accumulation rate of TiO₂ as an indicator of rates of erosion and for normalization of trace metal accumulation rates is in question for lakes where the flux of TiO₂ from the atmosphere varies and is a significant fraction of the total flux of TiO₂ to the sediment.This is the thirteenth of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D. F. Charles and D. R. Whitehead are guest editors for this series.  相似文献   

柴达木察尔汗盐湖贝壳堤剖面介形类组合及其环境意义   总被引：3，自引：0，他引：3       下载免费PDF全文

张虎才  王强  彭金兰  陈光杰 《第四纪研究》2008,28(1):103-111

柴达木盆地察尔汗贝壳堤剖面记录了约39.7～17.514CkaB.P.期间古湖泊高湖面扩张、收缩的演化历史。剖面中丰富的介形类,皆为我国东部山间盆地～平原区系与西部高原区系常见种。依据青海地区现代介形类分布调查,可知研究剖面高湖面发育期为淡水湖,其中高分异度介形类组合代表近静水的浅湖环境,单种或近单种土星介大量出现层位指示缓流水环境,大量原生双壳类共生可能指示静水、较深水环境。据地层中介形类分布,自下而上划分为7个组合-沉积环境带,分别为:①少量湖沼种出现（积水洼地形成带）——湖泊前期,②单种缓流水种连续出现（湖泊初始形成带）——高湖面初始形成期,③高分异度组合、介形类富集（浅水大湖带）——高湖面水深加大期,④中分异度组合、介形类少量出现（深湖带）——高湖面最盛期,⑤中分异度组合、介形类少量出现、双壳类连续富集（湖泊变浅带）——高湖面略下降期,⑥缓流水介形类繁盛、双壳类多少不等（湖泊水位下降带）——古湖泊退缩期和⑦介形类稀少带——古湖泊快速消亡期。贝壳堤剖面所见双壳类在现代介形类调查区域没有发现,它们在地层中的出现,进一步指示大体相当MIS3阶段时期柴达木盆地比现代更温暖的气候背景,降水条件好于现代。  相似文献   

基于空间信息技术的堰塞湖库容分析方法研究     

陈晓玲  陆建忠  蔡晓斌  李辉  殷守敬 《遥感学报》2008,12(6)

快速准确计算堰塞湖库容,对了解地震堰塞湖险情具有重要的意义.利用遥感和地理信息系统等空间信息技术,提出了一种基于像素的三维水面的计算动库容的方法,能准确计算水面为曲面,包括动库容在内的总库容.该方法利用遥感影像提取水体边界线,与DEM求交后可得到带高程的边界点,利用空间插值技术获得三维水面,然后利用库容计算模型求解.同时,在分析该算法计算效率的基础上,提出了基于河流分段的库容计算优化算法,最后通过实验对比分析了该方法的合理性和优越性.  相似文献   

长江中下游湖泊沉积物铅污染记录——以洪湖、固城湖和太湖为例   总被引：13，自引：8，他引：5       下载免费PDF全文

姚书春  薛滨  朱育新  夏威岚  李世杰 《第四纪研究》2008,28(4):659-666

2002～2005年在长江中下游的洪湖、固城湖和太湖分别采集了沉积物柱样钻孔,测定了总有机碳（TOC）和金属元素包括Pb,Al,Fe,Ti等,并采用²¹⁰Pb和¹³⁷Cs进行了近代沉积物定年。研究结果表明,洪湖钻孔平均沉积速率为0.15cm/a,固城湖平均沉积速率在0.067cm/a,太湖平均沉积速率为0.35～0.41cm/a。根据湖泊沉积物中铅元素与参考元素（Al,Fe和Ti）浓度和TOC的相关关系建立了回归方程,线性关系极显著（p<0.001）。根据回归方程获取了钻孔中铅的背景值变化,研究表明近代沉积物中金属铅不仅仅来源于自然的作用,而人类活动导致铅的累积发生时间都在20世纪70年代,从一个侧面也说明利用沉积物铅含量变化进行断代存在可能性。对太湖钻孔而言,其污染程度要高于洪湖和固城湖。研究结果表明近30年来洪湖和固城湖人为造成湖泊沉积物铅累积量在不断增加,其沉积物铅污染有进一步加重的趋势,应受到科学家和管理部门的关注。  相似文献   

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Playa——A Coupled Model of Reactive olute Transport and Chemical Equilibrium in a Multi-component Underground Brine System     

LI Wenpeng  LIU Zhenying 《《地质学报》英文版》2008,82(5)

Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea oftransport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory.Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/Magnesium in the mining of salt deposits in Qarhan Salt Lake.  相似文献   

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Piaya——A Coupled Model of Reactive Solute Transport and Chemical Equilibrium in a Multi-component Underground Brine System     

LI Wenpeng 《《地质学报》英文版》2008,(5)

Firstly,the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory.The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented,which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake.And secondly,with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference,a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile,the model was applied to model potassium/magnesium transport in Qarban Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarban Salt Lake.  相似文献   

青海省柴达木盆地西北缘盐类矿产遥感预测研究     

张彤蕴  朱谷昌  杨自安  石菲菲  张建国 《矿产与地质》2008,22(6):551-555

利用ETM多光谱遥感图像,在对盐湖区的遥感影像特征和主要地物光谱特征分析的基础上,通过波段组合变换,压抑粘土及砂砾层等地物的影响,将盐类矿产信息增强提取出来。对比前人的钾盐矿田勘查成果,所提取的盐类信息异常与现代新盐带、湿盐滩和现正在开采的钾盐矿区十分吻合。结合区域地质背景与成矿条件的分析研究,圈定了4个预测区、9处有利地段,为进一步盐类矿产勘查提供了科学依据和目标地。  相似文献   

太湖流域土壤重金属元素污染历史的重建:以Pb、Cd为例   总被引：5，自引：1，他引：4  

成杭新  赵传冬  庄广民  夏威岚  刘英汉  杨柯  聂海峰 《地学前缘》2008,15(5):167

太湖是位于长江下游的一个大型浅水湖泊,通过对4个代表太湖不同沉积环境的湖底沉积剖面的137Cs和210Pb沉积定年,重建太湖湖底沉积物和太湖来水流域土壤Cd、Pb的污染历史。结果显示:1980年以前,太湖底积物中Cd、Pb含量与流域内的自然背景含量相当,1980年以后,湖底沉积物中的Cd、Pb含量显著增高,这与我国大规模工业化进程的起始时间基本一致,推测工业化进程是湖底沉积物中Cd、Pb含量增加的主要原因。1900年以来太湖湖底沉积物中累积含有Cd和Pb分别为146t和25980t,其中苕溪来水提供的Cd和Pb分别为40t、6777t,宜溧河来水提供的Cd、Pb分别为36t、6023t,其他来水(洮、滆、运河)提供的Cd、Pb分别为71t、13179t,其他来水是太湖Cd、Pd累积的主要输入途径。Cd、Pb累积的高峰期为20世纪80—90年代,1980年以来,运河来水Cd、Pb的输出通量为28.26t、3419t;苕溪流域Cd、Pb的输出总量分别为13.70t、1585t,其中人为源的Cd、Pb为8.90t、610t,人为源输出的Cd、Pb通量占总输出量的64.96%和38.47%;宜溧河流域Cd、Pb的输出总量分别为10.09t、1063t,人为源的Cd、Pb分别6.96t和500t,人为源输出的Cd、Pb通量占总输出量的68.68%和47.08%,表明太湖流域人类活动所导致的Cd已超过自然剥蚀过程,因此削减工业化进程中的Cd、Pb排放总量,控制太湖运河来水的输出通量是改善太湖底积物Cd、Pb环境质量的关键措施。  相似文献   

The Glueckstadt Graben of the North-German Basin: new insights into the structure from 3D and 2D gravity analyses   总被引：1，自引：0，他引：1  

Tamara Yegorova  Yuriy Maystrenko  Ulf Bayer  Magdalena Scheck-Wenderoth 《International Journal of Earth Sciences》2008,97(5):915-930

The structure of the Glueckstadt Graben has been investigated by use of 3D gravity backstripping technique and by 2D gravity and magnetic modelling. Subtracting the gravity effects of the Meso-Cenozoic sediments together with Permian salt reveals a positive residual anomaly within the Glueckstadt Graben. This anomaly includes two local maxima over the Westholstein and Eastholstein Troughs. The 2D gravity models point to the presence of a high-density body within the lower crust of the Glueckstadt Graben. In addition, the results of 2D magnetic modelling indicate that the central part of the high-density body is overlain by an area with high susceptibility. Most probable, the formation of this high-density body is a result of complex poly-phase tectonic history of the study area. Finally, the results of gravity modelling indicate that Permian salt is not homogeneous. 3D gravity analysis and, especially, 2D gravity modelling have distinguished the differences in degree of salt saturation in salt-rich bodies, and elucidate the proportion of Rotliegend salt.  相似文献   

松辽盆地白垩纪湖泊水体温度与古气候温度估算   总被引：2，自引：0，他引：2  

申家年  王庆红  何江林  卢双舫 《吉林大学学报(地球科学版)》2008,38(6)

湖泊沉积物沉积的第一场所是湖底,湖底温度的高低影响沉积有机质的保存,也影响湖底下部地层的温度。了解古水体温度尤其是古水底温度情况成为评估松辽盆地白垩系生物气勘探前景的必要研究内容之一。根据已有的古气候研究成果与现今气候对比,得出白垩纪松辽盆地年平均气温约为14~24℃。再根据水库温度的计算方法和利用已有的古纬度及古水深的研究成果计算得出,白垩纪松辽盆地古湖盆水体表面温度为17~25℃;水深大于20 m的深湖区,水底温度为6.2~12.5℃;湖底最深处温度为4.0~11.3℃;青山口组和嫩江组沉积时期,湖水分层明显,湖底温度季节性变化很小且温度较低,约为8℃。湖底的低温对松辽盆地白垩纪生物气勘探是有利的。  相似文献