Monoterpene concentrations in and above a forest of scots pine

Diurnal and vertical ambient air measurements of the monoterpenes have been made in and above a Scots pine (Pinus sylvestris) forest of central Sweden, within the boreal northern coniferous biome. Sampling was done with Tenax TA, and analysis by GC and ion trap detection. Daytime mixing ratios were on the order of tenths of a ppbv from the forest floor to the top of the forest, and a factor of 2 or 3 lower above the forest. Mixing ratios at night were at the ppbv level, highest near the forest floor and the crown, and decreased with height above the forest. The highest total concentration observed was 8 ppbv inside the forest at 3 am (GMT). The average terpene composition was 3-carene 32%, -pinene 29%, limonene 18%, -pinene 10%, -phellandrene 7%, camphene 5%, and sabinene at less than 2%. The 3-carene/-pinene ratio varied with wind direction and speed, relative humidity, and wet/dry vegetation, but not with ozone or NO₂ concentration, solar radiation, or temperature. Variations in the observed terpene composition at the sampling site are mainly caused by the influence of other vegetation in the vicinity of the site. It would seem that wet Scots pine emits more 3-carene relative to -pinene than does dry pine.     

High-resolution sedimentary record of lead in the coastal mud of the East China Sea in the past one hundred and fifty years

In the East China Sea （ECS）, there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence （XRF） techniques and Thermal Ionization Mass Spectrometry （TIMS） were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the ＂Reform and Open Policy＂ in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River （Yangtze River） catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition.     

Heavy metals in freshly deposited sediments of the river Subernarekha, India: an example of lithogenic and anthropogenic effects

Heavy metal distribution patterns in river sediments aid in understanding the exogenic cycling of elements as well as in assessing the effect of anthropogenic influences. In India, the Subernarekha river flows over the Precambrian terrain of the Singhbhum craton in eastern India. The rocks are of an iron ore series and the primary rock types are schist and quartzite. One main tributary, the Kharkhai, flows through granite rocks and subsequently flows through the schist and quartzite layers. The Subernarekha flows through the East Singhbhum district, which is one of India’s industrialised areas known for ore mining, steel production, power generation, cement production and other related activities. Freshly deposited river sediments were collected upstream and downstream the industrial zone. Samples were collected from four locations and analysed in <63-μm sediment fraction for heavy metals including Zn, Pb, Cd and Cu by anodic stripping voltammetry. Enrichment of these elements over and above the local natural concentration level has been calculated and reported. Sediments of the present study are classified by Muller’s geo-accumulation index (I _geo) and vary from element to element and with climatic seasons. During pre-monsoon period the maximum I _geo value for Zn is moderately to highly polluted and for Cu and Pb is moderately polluted, respectively, based on the Muller’s standard. Anthropogenic, lithogenic or cumulative effects of both components are the main reasons for such variations in I _geo values. The basic igneous rock layer through which the river flows or a seasonal rivulet that joins with the main river may be the primary source for lithogenic components.     

Experimental and numerical studies of rock salt strain hardening

The work presented in this paper comes as part of a research program dealing with the thermomechanical behaviour of rock salt. It aims to study laboratory and in-situ long-term behaviour by means of creep tests with deviator and temperature changes. The laboratory results, using a triaxial multi-stages creep tests, highlighted the strain hardening character of rock salt. Furthermore, the in-situ results, using a borehole dilatometer multi-step creep test, have shown that the drilling is carried out in a weakly stressed pillar. The interpretation of the laboratory results, using the J.LEMAITRE law, did not indicate full agreement with all the test results. As a result a ‘double’ J.LEMAITRE model, which takes into account a double strain hardening variable, has been put forward. The validation of this model on the laboratory creep tests is very satisfactory. Furthermore, the activation energy seems satisfactory to represent the influence of the temperature. The in-situ behaviour modelling is clearly more complex than the modelization based on laboratory tests. In fact, it seems that if the rock salt behaviour is maintained by J.LEMAITRE law, it is necessary to vary with the stress, at least, one of the parameters assumed constant in the basic law.     

大气CO2浓度升高对土壤中不同粒级碳的影响

不同粒级土壤中的碳有着不同的周转规律，在高CO2浓度条件下，它们含量的变化将在一定程度上反映土壤碳是累积还是减少，对明确土壤碳的变化趋势有重要意义．采用田间培养试验初步模拟研究在高CO2浓度条件下土壤不同粒级碳的分布．结果表明，加入秸秆培养1年，由于CO2浓度升高的原因导致在低氮（LN）、常规氮（NN）和高氮（HN）水平下土壤中碳分别增加0．01、1．10、1．22g／kg，表现为粒级〈53μm土壤颗粒中碳分别增加1．53、2．19、2．70g／kg．粒级〈53μmm土壤颗粒碳量的增加，主要是由于其重量分配百分数显著增加36．2％，碳浓度增加5．4％；粒级〉250μm和250～53μm土壤颗粒部分虽然其碳浓度分别增加20．8％和17．3％（P〈0．05），怛由于重量分配百分数分别显著降低22．8％和36．1％，结果碳量降低．试验表明高CO2浓度导致不同粒级土壤的分配及碳浓度的变化；高氮施肥水平下有增加土壤碳量特别是小粒级土壤碳量的趋势．     

龙永煤田危机矿山资源接替的几种勘探模式

通过龙永煤田现有煤矿状况调查分析发现：许多矿井已步入“花甲之年”，接近矿井服务年限。为了保障我省能源安全，应当采用有效勘探方法，方能使它们“返老还童”。研究发现危机矿山延长服务年限的几种勘探模式是：其一为扩大（延伸）勘探模式；其二为小型井田（块段）勘探模式；其三为资料分析研究模式。经探采对比发现，采用这三种勘探模式后，产生了巨大的经济效益，使一大批老矿井青春再度焕发。     

图像平滑算法比较研究及改进策略

图像平滑作为去除图像中含有噪声的图像增强处理技术，是各种与图像有关软件中必不可少的功能模块。文中在分析噪声模型的基础上，对均值平滑、中值平滑、边缘保持平滑等技术从图像处理空间域中的算法原理、实现方法及效率等方面进行了详细比较。针对图像中含有的不同噪声模型，通过多次试验，得出了值得从事图像处理研究者参考的结论。这将有助于提高图像处理软件开发的效率。     

内陆盆地的盐分布与平衡分析研究

在总结已有研究成果和系统分析水文、土壤、灌溉、水盐监测资料的基础上,应用系统分析方法、水盐运移理论和水盐平衡原理,通过对盆地、流域、灌区、农田和土壤剖面等不同层次盐分分布与盐平衡分析计算,分析了内陆盆地不同层次的“干排盐”形成与特征,认为干排盐是必不可少的,必须系统地考虑不同层次干排盐出路与动力条件,才能有效地治理灌区盐渍化问题。     

半无限空间中圆形孔洞周围SH波的散射

建立了求解在含有圆形孔洞的弹性半空间中SH波散射与圆形孔洞附近动应力集中问题的解析方法。利用SH波散射的对称性和多极坐标的方法，构造了一个可以预先满足半空间自由表面上应力自由边界条件的圆形孔洞对SH波散射的波函数。利用这一波函数，则可将该问题转化成对一个圆形孔洞散射的求解问题。该问题的解答最终又可归结为对一组无究代数方程组的求解问题，并可利用截断有限项的方法对其进行计算，最后给出了有关圆形也洞附近动应力集中问题的算例和数值结果，并讨论了波数与圆孔至自由边界距离变化对动应力集中的影响。