Further studies of the temperature dependence of the rate coefficients for the reactions of OH with a series of ethers under simulated atmospheric conditions

The following temperature-dependent rate coefficients (k/cm³ molecule^–1 s^–1) of the reactions of hydroxyl radicals with aliphatic ethers have been determined over the temperature range 247–373 K by a competitive flow technique: diethyl ether,k _OH=5.2×10^–12 exp[(262±150)/T]; methyln-butyl ether,k _OH=5.4×10^–12 exp[(309±150)/T]; ethyln-butyl ether,k _OH=7.3×10^–12 exp[(335±150)/T]; di-n-butyl ether,k _OH=5.5×10^–12 exp[(502±150)/T] and di-n-pentyl ether,k _OH=8.5×10^–12 exp[(417±150)/T]. The data have been measured relative to the rate coefficientk(OH + 2,3-dimethylbutane)=6.2×10^–12 cm³ molecule^–1 s^–1 independent of temperature.Previous discrepancies in the room-temperature rate coefficients for the OH reactions with ethyln-butyl ether and di-n-butyl ether, obtained in the flow and static experiments of Bennett and Kerr (J. Atmos. Chem. 8, 87–94, 1989;10, 29–38, 1990) compared with those of Wallingtonet al. (Int. J. Chem. Kinet. 20, 541–547, 1988;21, 993–1001, 1989) and of Nelsonet al. (Int. J. Chem. Kinet. 22, 1111–1126, 1990) have been resolved. The results are considered in relation to the available literature data and evaluated rate expressions are deduced where possible. The data are also discussed in terms of structure-activity relationships.     

Hydrogeological and geochemical study of the springs in San Severino Lucano territory (Southern Italy)

A hydrogeological and geochemical study is presented for the San Severino Lucano region of southern Italy. In this region, groundwater circulation occurs in rocks lithologically different from one another (metaophiolites, carbonate rocks, etc.). Many springs drain this region. The Frido springs are the most important both for their great volume of flow and for their water quality. A water balance estimated for the recharge area of the Frido springs suggests that during the period 1938–1958 the evapotranspiration represents 54.8 percent, runoff 21.2 percent, and infiltration to groundwater 34 percent of rainfall. The springs studied have a meteoric origin and their waters are mostly acid carbonate-alkaline earth type. The reservoir rocks appear to be the only discriminating factors for the chemical composition of the waters analysed.     

The geothermal regime of the northern Yukon and Mackenzie delta regions of northwest Canada — studies of two regional profiles

Temperature data from deep petroleum exploration wells and thermal conductivity estimates based on net rock analysis data have been used to make terrestrial heat flow estimates along two profiles across the sedimentary strata of the Mackenzie Delta, northern Yukon, and offshore Beaufort Sea regions.Both profiles exhibit low heat flow values that range from 34 mWm^–2 to 58 mWm^–2, and little change occurs over large distances in the continental part of the area. Low heat flow values (<40 mWm^–2) occur in the Beaufort-Mackenzie Basin and Rapid Depression, both of which are areas of thick successions of Cretacecus and Tertiary clastic sedimentary strata. High heat flow values of almost 80 mWm^–2 occur to the south in the Taiga Nahoni Foldbelt and values as high as 60 mWm^–2 are indicated along the Aklavik Arch Complex, northeast of Aklavik.The regional variations of effective thermal conductivity are insufficient to account for the heat flow variations along the profiles, and so these may indicate deep radiogenic or other heat sources.     

中国海洋潮汐40年来研究进展

近４０年来我国海洋潮汐的研究获得显著进展。本文分别对潮汐的分析、推算，潮汐谱估计，平均海面，潮波理论和数值研究等方面进行阐述。潮汐分析、推算已有１００多个分潮的模型可供应用，交点订正系统除利用ｆ、ｕ的１１个公式外，还根据Ｗ．Ｈｏｒｎ的ｊ．ｖ模型，利用Ｄ．Ｅ．Ｃａｒｔｗｒｉｇｈｔ新的引潮势展开推出５９个ｊ、ｖ公式，后者理论上更为精确，它反映了近代天文学研究进展的成就。平均海面提出一种随机动态分析、预测模型，能比较可靠地求出平均海面长期变化趋势，并能对未来几年内作出月平均海面的预报。潮波理论结合中国海实际，研究潮汐摩擦规律及其效应，已能说明中国海主要分潮波系统的形成及其分布变化，潮波数值计算和模拟取得很大的发展，有些在建港和海洋开发利用中已经得到应用，是一种很有前途的研究方法。潮汐表的编算水平高、范围遍及各国主要海港，受到用户的欢迎。总起来说，我国海洋潮汐的研究工作，经４０年来的努力，从总体上说达到了国际水平，某些方面居领先地位。但整个潮汐的观测站网、仪器装备、监测水平和精度，仍有待改进提高。     

Geological and petrologic evolution of seamounts near the EPR based on submersible and camera study

Observations from 17 ALVIN dives and 14 ANGUS runs plus laboratory study of basalt samples collected with ALVIN help to constrain the morphologic, volcanic and petrologic evolution of four seamounts near the East Pacific Rise (EPR). Comparison among the four volcanoes provides evidence for a general pattern of near-EPR seamount evolution and shows the importance of sedimentation, mass wasting, hydrothermal activity and other geologic processes that occur on submerged oceanic volcanoes. Seamount 5, closest to the EPR (1.0 Ma) is the youngest seamount and may still be active. Its summit is covered by fresh lavas, recent faults and hydrothermal deposits. Seamount D is on crust 1.55 Ma and is inactive; like seamount 5, it has a breached caldera and is composed exclusively of N-MORB. Seamounts 5 and D represent the last stages of growth of typical N-MORB-only seamounts near the EPR axis. Seamounts 6 and 7 have bumpy, flattish summits composed of transitional and alkalic lavas. These lavas probably represent caldera fillings and caps overlying an edifice composed of N-MORB. Evolution from N-MORB-only cratered edifices to the alkalic stage does not occur on all near-EPR seamounts and may be favored by location on structures with relative-motion-parallel orientation.     

Modelling hourly and daily open‐water evaporation rates in areas with an equatorial climate

Evaporation rate estimation is important for water resource studies. Previous studies have shown that the radiation‐based models, mass transfer models, temperature‐based models and artificial neural network (ANN) models generally perform well for areas with a temperate climate. This study evaluates the applicability of these models in estimating hourly and daily evaporation rates for an area with an equatorial climate. Unlike in temperate regions, solar radiation was found to correlate best with pan evaporation on both the hourly and daily time‐scales. Relative humidity becomes a significant factor on a daily time‐scale. Among the simplified models, only the radiation‐based models were found to be applicable for modelling the hourly and daily evaporations. ANN models are generally more accurate than the simplified models if an appropriate network architecture is selected and a sufficient number of data points are used for training the network. ANN modelling becomes more relevant when both the energy‐ and aerodynamics‐driven mechanisms dominate, as the radiation and the mass transfer models are incapable of producing reliable evaporation estimates under this circumstance. Copyright © 2006 John Wiley & Sons, Ltd.     

Silurian granites of northern Kazakhstan: U-Pb age and tectonic position

The isotopic-geochronological studies of zircons from granites of the Borovoe, Makinsk, and Zhukei massifs located in the eastern part of the Precambrian Kokchetav median massif revealed that they were formed during the relatively brief period from 431 to 423 Ma ago, which allowed them to be united into the Early Silurian Borovoe Complex.     

岩质滑坡的时间预报与水力启动模型

摘 要 岩质滑坡发生时间的适时超前预报是一个世界性难题,之所以长期不得其解,主要是缺乏对滑坡成生机理的明晰认识和未建立正确的量化模型。本文根据我国长江三峡工程库岸和西南山区积累的大量滑坡实例调查资料并参考国外的一些研究成果,排除了地形控制论与地层控制论观点,阐明了滑坡形成的必要条件是斜坡具有易滑结构;滑坡发生的充分条件是有一定强度的诱发因素作用。故而诱发因素的动态变化对滑坡发生的时间具决定意义。 鉴于地下水诱发的岩质滑坡分布最广,为建立正确的水力启动模型,本文归纳了近代典型岩质滑坡的主要特征:（1）滑面是导水性差异最大的贯通面;（2）滑体长度大而厚度小,长厚比多在20左右;（3）滑坡前缘段先启动;（4）临滑前在前缘段有渗水、冒水或喷水现象;（5）出水宽度之和远小于前缘段总宽度。根据这些特征和水力学、水文地质学的成熟理论指出jennings（1970）等人提出的岩质斜坡稳定性模型存在下列问题:（1）未表明贯通面上岩体重力分布状况;（2）空隙水压力的分布特征与前述滑坡现象和水力学原理相悖;（3）未考虑通水率问题。然后,本文按顺向坡中的易滑超倾坡和椅状坡两个类型建立了斜坡稳定性模型和滑坡水力启动临界值（基本）计算公式。提出潜滑面的综合内摩擦角和通水率的确定方法:（1）滑坡反算;（2）对无水压滑坡滑面倾角和渗水边坡通水率进行观测统计;（3）剪切试验和简易水文地质试验;（4）物探方法。 本文还讨论了新模型的实用意义和应用范围,并对解决这类复杂地质灾害问题的研究途径发表了作者的认识,强调了积累经验的重要性。     

多目标区域地球化学调查与生态地球化学--第四纪研究与应用的新方向

多目标区域地球化学调查是继区域化探全国扫面计划之后勘查地球化学的又一项重要进展。要点是以多目标区域地球化学调查为基础,进行生态地球化学评价、评估和预警。以第四纪地球化学巨量信息与生态环境研究相结合,吸纳与综合其他学科的思想、观点、方法和研究成果,进行多学科延伸和社会经济多领域应用,是第四纪研究与应用的新方向,使地学立于21世纪环境科学之林。     

Remote sensing needs and capabilities in West Africa

The greatest advantage of remote sensing over conventional measurements lies in the opportunity to carry out detailed spatio-temporal analysis of land and ocean features on a very frequent basis. This paper analyses the contribution of satellite imagery to atmospheric, geophysical and ocean studies and management in West Africa since the early 1980s.The detailed application of data from optical sensors (e.g. Meteosat,NOAA/AVHRR, SPOT,L andsat TM, etc.) for weather prediction, hydrogeological, landuse/cover and cartographic studies has been acknowledged. However, the use of microwave (e.g. SAR) and optical data for ocean monitoring and studies in the sub-region is still very limited. Even though sufficient remote sensing expertise and infrastructure is perceived in the region, no clearly defined networking or database exists.