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991.
湖南洞庭湖地区土壤中Hg的来源 总被引:1,自引:0,他引:1
Hg污染已成为全球性的环境问题,尤其是Hg对土壤的污染,因其具有隐蔽性、不可逆性和长期性的特点,对陆生生态系统构成潜在的巨大威胁,因此查明土壤中Hg的来源非常重要。运用生态地球化学填图的指导思想,对湖南洞庭湖地区土壤剖面分析和成土过程研究后发现,表层土壤中Hg含量的高低与成土母质中Hg的含量有很好的对应性,成土过程对土壤中Hg的含量也有显著的影响。 相似文献
992.
对武汉汤逊湖湖泊沉积物T06-1样芯进行了磁性测量、重金属分析和粒度分析,探讨了利用磁参数追踪、指示城市湖泊重金属污染的可行性.结果表明,低矫顽力的亚铁磁矿物主导了沉积物的磁性特征.磁参数χ,SIRM和ARM与重金属Cr,Zn,Cu和Pb呈现较为一致的垂向变化特征:55cm之下,磁参数值和重金属的含量均较低且稳定;在50~10 cm之间,两者基本呈现随深度的减小而增加的趋势,其中在20~10 cm区间,出现小范围内波动;而10cm至表层,元素含量和磁参数值随深度减小而急剧增加.选取粘土(<4μm)对沉积物中Cr,Zn,Cu和Pb进行粒度校正的结果显示:校正后元素的变化趋向于平稳,但在表层的10cm处Cr,Pb,Zn和Cu的含量仍然较高,表明了表层沉积物中金属元素的含量主要受人类活动的影响.相关分析也表明了磁参数χ,SIRM和ARM与重金属Cr,Pb,Zn和Cu之间均呈显著相关关系(0.62≤R≤0.86),表明磁参数可以用于追踪和指示汤逊湖湖泊沉积物重金属污染. 相似文献
993.
三维地震数据可视化原理及方法 总被引:5,自引:0,他引:5
可视化是实现三维地震数据真三维解释的有效方法,本文介绍了三维地震数据可视化的基本原理,论述了用光线投射算法实现可视化的主要步骤,详细推导了合成可视化图像的计算公式,分析了阻光度曲线的物理意义及对可视化图像的调节作用,并用两个实际三维地震数据进行了试验.结果表明该方法能够由原始三维地震数据直接对地质体进行成像,能将分散的、孤立的信息互相联系起来,揭示隐藏在数据中的地质现象和规律. 相似文献
994.
依据1970年以来记录相对完备的MSge;5.0地震序列资料,统计研究了中国大陆余震分布尺度与序列最大地震震级M0及最大地震破裂形式之间的关系. 在95%置信概率下,考虑主震破裂形式, 分序列类型给出了余震分布尺度与M0之间的统计关系. 定性而言,余震分布尺度的对数lgR与M0正相关, 但数据分布较为离散. 分类型来看, 孤立型序列余震分布尺度与M0之间统计相关程度低, 余震分布尺度介于5~60 km之间; 主余型序列lgR与M0正相关; 多震型序列当M0le;6.2时lgR与M0之间相关性不显著,余震分布尺度介于5~70 km之间, 当M0ge;6.3时lgR与M0线性相关. 统计结果还表明, 走滑近走滑及斜滑型主震所导致序列类型比例之间没有显著差异,而倾滑近倾滑型主震(主要为逆断型破裂)所导致的主余型序列所占比例较高, 孤立型及多震型序列所占比例则相对较低. 对比研究显示, 当M0较高时,余震分布尺度主要取决于主震大小而与主震破裂形式关系不明显. 相似文献
995.
Al James 《Geoforum》2007,38(2):393-413
In recent years, economic geographers have drawn extensively upon notions of ‘cultural embeddedness’ to explore how spatially variable sets of cultural conventions, norms, values and beliefs shape firms’ innovative performance in dynamic regional economies. However, our understanding of these causal links remains partial, reinforced by an ‘over-territorialised’ conception of cultural embeddedness which sidelines the role of institutional actors operating outside and across the boundaries of ‘the local’. So motivated, this paper offers a theoretically-informed - and theoretically informing - empirical analysis of the high tech regional economy in Salt Lake City, Utah to explore the everyday causal mechanisms, practices and processes - both local and extra-local - through which firms’ cultural embedding within the region is manifested, performed and (un)intentionally (re)produced. In so doing, this paper aims to further our understanding of the constitutive entanglement and complex interweaving of cultural/economic practices, and to contribute to the development of an in-depth empirical corpus of work which compliments the exciting conceptual developments that have largely dominated cultural economic geography over the last decade. 相似文献
996.
The abundance and preferences of individual invertebrate populations (including zooplankton) closely associated with the substrates provided by aquatic plant structures and open-water areas of Lake Nasser were quantified in this study in order to gain understanding of the importance of submerged macrophyte for invertebrate diversity, and their relation to water properties. The following water parameters were measured: temperature, pH, dissolved oxygen (DO), total dissolved salts, electrical conductivity, turbidity, total suspended solids, carbonate, bicarbonate, nitrate, nitrite, phosphate, sulphate, silica, potassium, total hardness, calcium and magnesium.Five macrophyte species were recorded: Myriopyllum spicatum, Najas horrida, Potamogeton schweinfurthii, Potamogeton pectinatus and Vallisneria spiralis. In total 67 invertebrate species were recorded, comprising 39 Rotifera, 12 Cladocera, 4 Copepoda, 4 Insecta, 2 Protozoa, 2 Ostracoda and one species of Turbellaria, Tardigrada, Annelida and Nematoda. Thirty-seven species were exclusively epiphytic, 11 species were collectively planktonic and 19 species were found in both habitats. The greatest abundance of epiphytic invertebrates occurred in association with N. horrida-P. schweinfurthii community.The results indicated that total suspended solids (TSS), TH and NO2 are the most influential water variables on the distribution of the aquatic macrophyte samples and their invertebrate communities. Also, the study indicates that water variables have a higher impact on the aquatic macrophytes than on the associated invertebrate populations. P, NO3, K, Na, Mg, Cl and DO were the most influential water variables that dictate the distribution of invertebrate groups recorded in the open-water zone. Water temperature, electric conductivity, pH, NO2, SO4−−, SiO3−, CO3−− and turbidity have a lesser influence of the distribution of the invertebrates recorded in this zone. 相似文献
997.
P. Bogaert D. Fasbender 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):695-709
In spite of the exponential growth in the amount of data that one may expect to provide greater modeling and predictions opportunities,
the number and diversity of sources over which this information is fragmented is growing at an even faster rate. As a consequence,
there is real need for methods that aim at reconciling them inside an epistemically sound theoretical framework. In a statistical
spatial prediction framework, classical methods are based on a multivariate approach of the problem, at the price of strong
modeling hypotheses. Though new avenues have been recently opened by focusing on the integration of uncertain data sources,
to the best of our knowledges there have been no systematic attemps to explicitly account for information redundancy through
a data fusion procedure. Starting from the simple concept of measurement errors, this paper proposes an approach for integrating
multiple information processing as a part of the prediction process itself through a Bayesian approach. A general formulation
is first proposed for deriving the prediction distribution of a continuous variable of interest at unsampled locations using
on more or less uncertain (soft) information at neighboring locations. The case of multiple information is then considered,
with a Bayesian solution to the problem of fusing multiple information that are provided as separate conditional probability
distributions. Well-known methods and results are derived as limit cases. The convenient hypothesis of conditional independence
is discussed by the light of information theory and maximum entropy principle, and a methodology is suggested for the optimal
selection of the most informative subset of information, if needed. Based on a synthetic case study, an application of the
methodology is presented and discussed. 相似文献
998.
999.
中天山东段古生代淡色花岗岩的发现及其构造意义 总被引:2,自引:4,他引:2
在吐鲁番地区底坎尔南的中天山构造带,新发现含电气石和石榴石的淡色花岗岩侵入于富铝泥质片岩系中。SHRIMP U—Pb 锆石年代学分析,表明淡色花岗岩的形成不晚于354±16Ma,同时还给出了600~1200Ma 的原岩继承锆石年龄。淡色花岗岩的发现及其形成年龄的确定,表明中天山在354Ma 前具有与陆缘弧背景相似的构造环境,并在354Ma 前完成碰撞过程,为进一步研究古生代天山构造演化提供了新的证据。 相似文献
1000.
A model for estimating the value of sampling programs and the optimal number of samples for contaminated soil 总被引:1,自引:0,他引:1
Pär-Erik Back 《Environmental Geology》2007,52(3):573-585
A model is presented for estimating the value of information of sampling programs for contaminated soil. The purpose is to calculate the optimal number of samples when the objective is to estimate the mean concentration. A Bayesian risk–cost–benefit decision analysis framework is applied and the approach is design-based. The model explicitly includes sample uncertainty at a complexity level that can be applied to practical contaminated land problems with limited amount of data. Prior information about the contamination level is modelled by probability density functions. The value of information is expressed in monetary terms. The most cost-effective sampling program is the one with the highest expected net value. The model was applied to a contaminated scrap yard in Göteborg, Sweden, contaminated by metals. The optimal number of samples was determined to be in the range of 16–18 for a remediation unit of 100 m2. Sensitivity analysis indicates that the perspective of the decision-maker is important, and that the cost of failure and the future land use are the most important factors to consider. The model can also be applied for other sampling problems, for example, sampling and testing of wastes to meet landfill waste acceptance procedures. 相似文献