湖泊碳酸盐在过去环境变化研究中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

郭金春  马海州  宋恩玉  陈宁 《盐湖研究》2008,16(2):66-72

国内外的研究成果表明,湖泊沉积碳酸盐矿物及其微量元素、同位素分布特征记录了全球或区域古气候环境演变历史,可以从中提取大量定量化的古气候参数。因此,可以根据湖泊碳酸盐矿物的含量和碳、氧同位素变化等信息推知其形成时期的气候环境,重建古环境,揭示气候环境演变的规律。湖泊碳酸盐是一种研究古环境演化重要的代用指标,在过去气候环境变化研究中有广阔的应用前景。  相似文献   

梭梭幼苗死亡与土壤和大气干旱的关系研究   总被引：8，自引：3，他引：5  

田媛  李建贵  赵岩 《中国沙漠》2010,30(4):878-884

以古尔班通古特沙漠南缘沙漠中的一年生梭梭幼苗为研究对象,对环境气象因子、土壤含水率、幼苗根系垂直伸展状况、幼苗死亡动态进行了全生长期的连续监测研究。结果表明,尽管梭梭幼苗根系伸展迅速,当年可达1.5 m,幼苗死亡率动态变化仍然与土壤表层含水率显著相关,而与根区或深层含水率不显著相关。但统计分析结果显示,土壤表层含水率并不总是梭梭幼苗死亡率波动的主导因素。当土壤含水率低至0.82%时,无论大气干旱程度如何,幼苗死亡率都急剧升高;而当土壤含水率高于1.25%时,幼苗可以耐受大气干旱,幼苗死亡只与土壤表层含水率显著相关;当土壤含水率在0.82~1.25%之间时,幼苗死亡率与大气干旱程度（空气饱和差）显著相关。据此我们推测,当土壤表层含水率低于1.25%时,大气干旱主导死亡率的变化;反之,则土壤水分主导。  相似文献   

湖泊无机碳酸盐矿物氧同位素组成差值及其单矿物同位素组成的确定          下载免费PDF全文

曾承  吴鑫  钱晨阳 《盐湖研究》2010,18(1):21-28

湖积物中不同无机碳酸盐矿物常常混杂在一起,其氧同位素组成(δ18O)差异会影响碳酸盐δ18O环境信息提取的可靠性。不同矿物之间δ18O差值明显且幅度不一。20~25℃时生成的白云石比共生的方解石富集18O可能为0‰~9‰不等,亦或方解石比白云石可能更富集18O达0‰~12.3‰。常温状态,相同条件下形成的文石δ18O值较方解石高出0‰~1‰,或者方解石较文石δ18O值高出0‰~4.47‰。镁方解石中MgCO3的mol百分含量每增加1%,其δ18O值相对于纯方解石δ18O值增加0.06‰~0.17‰。在利用碳酸盐δ18O进行气候及环境研究时,不能根据某种差值进行校正,而应进行单矿物测试。由此,对不同无机碳酸盐矿物的分离及同位素测试、推算方法进行了归纳和述评。  相似文献   

Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in response to nitrogen supply and water stress   总被引：1，自引：0，他引：1  

F.Z. Wu  W.K. Bao  Z.Q. Zhou  N. Wu 《Journal of Arid Environments》2009,73(12):1067-1073

A greenhouse experiment was conducted to explore whether additional nitrogen (N) supply could enhance carbon (C) accumulation, and phosphorus (P) use efficiency (NUE_P) of Sophora davidii seedlings under dry conditions. Two-month-old seedlings were subjected to a completely randomized design with three water (80, 40 and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg⁻¹ soil) regimes. Water stress decreased C, N and P accumulation, NUE_P, N and P uptake efficiency (NUtE_N and NUtE_P) regardless of N supply. The S. davidii seedlings exhibited strong responses to N supply, but the responses were not consistent with the various N supply levels. Nl increased C, N and P accumulation, and improved NUE_P, NUtE_N and NUtE_P in the same water treatment. In contrast, Nh did few or even depress effects on C, N and P accumulation, and NUE_P, although NUtE_N and NUtE_P increased with Nh in the same water treatment. Even so, NUE_N decreased with increase of N supply in the same water treatment. The results suggested that appropriate or low N supply should be recommended for S. davidii seedling establishment in dry environment by improving C accumulation and NUE_P.  相似文献   

Functioning of intertidal flats inferred from temporal and spatial dynamics of O<Subscript>2</Subscript>, H<Subscript>2</Subscript>S and pH in their surface sediment   总被引：1，自引：1，他引：0  

Stefan Jansen  Eva Walpersdorf  Ursula Werner  Markus Billerbeck  Michael E Böttcher  Dirk de Beer 《Ocean Dynamics》2009,59(2):317-332

In this article, we describe the dynamics of pH, O₂ and H₂S in the top 5–10 cm of an intertidal flat consisting of permeable sand. These dynamics were measured at the low water line and higher up the flat and during several seasons. Together with pore water nutrient data, the dynamics confirm that two types of transport act as driving forces for the cycling of elements (Billerbeck et al. 2006b): Fast surface dynamics of pore water chemistry occur only during inundation. Thus, they must be driven by hydraulics (tidal and wave action) and are highly dependent on weather conditions. This was demonstrated clearly by quick variation in oxygen penetration depth: Seeps are active at low tide only, indicating that the pore water flow in them is driven by a pressure head developing at low tide. The seeps are fed by slow transport of pore water over long distances in the deeper sediment. In the seeps, high concentrations of degradation products such as nutrients and sulphide were found, showing them to be the outlets of deep-seated degradation processes. The degradation products appear toxic for bioturbating/bioirrigating organisms, as a consequence of which, these were absent in the wider seep areas. These two mechanisms driving advection determine oxygen dynamics in these flats, whereas bioirrigation plays a minor role. The deep circulation causes a characteristic distribution of strongly reduced pore water near the low water line and rather more oxidised sediments in the centre of the flats. The two combined transport phenomena determine the fluxes of solutes and gases from the sediment to the surface water and in this way create specific niches for various types of microorganisms.  相似文献   

湖泊自生碳酸盐氧同位素环境记录研究：（一）环境解释模型          下载免费PDF全文

曾承  王臣旗 《盐湖研究》2009,17(2):1-4

湖泊自生碳酸盐氧同位素组成(δ18OC)在区域气候与环境变化方面的应用研究近年来发展迅速,成果令人瞩目,保存在各类湖泊沉积物柱芯中的δ18OC记录揭示了湖泊水温乃至汇水区域气温,湖泊不同水深处的水温差异、湖泊水位、降水δ18O、冰川融水δ18O、湖水盐度等重要的气候和环境信息。对前人通过研究来自不同类型湖泊、具不同曲线形态的δ18OC记录提出的多种环境解释模型进行了归纳。  相似文献   

基于深度学习的区域生态安全时空模拟与预测     

陈工  李琦  金玲艳  梁贺明  莫玉琴 《地球信息科学学报》2017,19(7):915-923

区域作为人类、自然、社会共同作用和互相影响的复杂系统,对区域进行生态量化建模与模拟仿真,是实现区域可持续发展战略的关键。传统机器学习方法对区域生态系统建模取得了一定的成果,但难以确定学习特征和实现时空模拟。深度学习不需事先确定训练特征,具有优异的特征学习能力,能够提高模型预测精度,因此利用深度学习进行建模具有显著优势。本文使用植被净初级生产力（NPP）、气溶胶光学厚度（AOD）和人口格网数据,充分利用深度学习的优点,采用最优深度神经网络时空模拟,得到了河南省2007-2014年3 km分辨率的生态赤字空间分布图和河南省2015-2020年的生态赤字时间预测结果并进行分析,为区域生态的科学管理和建设供科学依据和参考。  相似文献   

Impact of global warming on drought in China     

Xian Xue  Tao Wang  Jian Guo  YuanHe Yang  Fei Peng  LiChao Liu 《寒旱区科学》2012,4(3):0201-0210

Spatial and temporal change patterns of air temperature (T), precipitation (P), relative humidity (RH), lower vapor pressure (VP), potential evapotranspiration (PET) and drought situation of 690 meteorological stations for all of China were evaluated in this study to understand the effects of warming on regional drought and hydrological processes. Here, the drought extent is expressed by aridity index (AI), which is the ratio of precipitation and reference crop evapotranspiration (ET₀) calculated by FAO Penman-Monteith equation, taking into account air temperature, atmospheric humidity, solar radiation, and wind. Our results indicate that there are different patterns of climate change from 1961 to 2008 and from 1981 to 2008. Little precipitation change occurred in China and ET₀ decreased from 1961 to 2008. But, the warming trend has intensified and the area with significant increasing precipitation has reduced since the early 1980’s and ET₀ has increased in most areas of China from 1981 to 2008 and decreased from 1961 to 2008. The areas affected by drought have shifted from North China and Northeast China to East China and South China since 1981. It is speculated that the increasing warming intensity after 1981 possibly strengthened the power of potential evapotranspiration and resulted in drought in most areas of Northeast China, North China, eastern Southwest China, and especially in East China and South China.  相似文献   

Improvement of Oxygen Release from Calcium Peroxide‐polyvinyl Alcohol Beads by Adding Low‐cost Bamboo Biochar and Its Application in Bioremediation          下载免费PDF全文

Chih‐Hung Wu  Shih‐Hsien Chang  Chi‐Wen Lin 《洁净——土壤、空气、水》2015,43(2):287-295

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Paramagnetic lattice defects in quartz for applications to ESR dating     

《Quaternary Geochronology》2015

Quartz is one of the minerals useful for ESR dating with many applications. Although the study has quite a long history since 1980's, ESR dating of quartz is still in a developing stage. After the basis in physics for the ESR signals in quartz is described, the current status of ESR dating of quartz is summarized for applications to fault gouge, tephra and sediment. Both basic studies for mechanisms and practical applications with independent age controls are still necessary to establish the protocols.  相似文献