A rationale for beach selection by the public on the coast of Wales, UK

Questionnaires were completed by 2306 beach users at 19 Welsh beaches with respect to beach selection parameters. The modal group of respondents was female aged 30–39. Beach choice was primarily determined by clean litter-free sand and seawater, followed by safety. Refreshment facilities and beach awards were deemed minor considerations by the public when choosing a beach to visit. Approximately 58 per cent of respondents were aware of beach award and rating schemes. Of coastal visitors interviewed for this paper, 67 per cent rated a beach as 'important' or 'very important' to their holiday, with just 2 per cent replying that they were unimportant.     

晋城市下河泉水源地开发利用可行性分析

在野外调查和收集现有资料基础上,对下河泉水源地水文地质条件、泉水流量动态、水源地保证程度与可能的环境问题进行了分析,论证了建立下河泉水源地的可行性.     

观光生态农业在生态农业旅游中的应用研究--以北京留民营的发展为例

观光生态农业和生态农业旅游都是近年来新兴的旅游产品,他们也越来越受到游客的青睐.作为观光生态农业模式典型的留民营村备受关注.本文以留民营的发展为例,阐述了观光生态农业在生态农业旅游中的优势,并提出了留民营开发生态农业旅游的模式.     

神头泉流量变化规律研究--灰色系统理论的具体应用

在分析神头泉流量衰减特征的前提下，利用灰色系统理论建立了描述神头泉流量变化规律的数学模型。以1985年为界，神头泉的流量变化过程可分为两个阶段，GM（1，1）模型与灰色预测校正模型则分别用于对这两个阶段的流量变化特征进行刻画。神头泉2000－2004年的流量预测值表明，在神头泉域保证90年代中期的高降水量和朔州市各地下水用户对泉域内的地下水不进行超采的基础上，神头泉的流量在未来的一段时间内会维持1993年以来的增长趋势。     

西昆仑地区塔木MVT型铅锌矿床成矿作用和成矿物质来源探讨

MVT型铅锌矿是西昆仑地区重要的铅锌矿床类型之一.为了探明西昆仑地区该类型矿床的成矿作用过程和成矿物质来源,本文以塔木矿床为例,在野外调研基础上,进行了光片鉴定、铅硫同位素、稀士元素和成矿元素研究,得到矿石中方铅矿的δ34SCDT为-5.04‰～+3.67‰,反映出油田卤水与深层卤水的混合特征;由铅同位素分析结果计算出表面年龄为461～481 Ma(早于泥盆纪438～410 Ma);由稀土元素分析数据得出岩(矿)石/球粒陨石标准化分配模式图表明,成矿物质主要来自地层.因而判定主要成矿物质可能来源于前泥盆系地层.喜马拉雅期逆冲推覆构造作用所引发的大规模热卤水运移、循环过程,导致矿质的进一步富集、沉淀.     

深海热泉生物——人类的基因资源宝库

广泛存在于大洋之中的深海热泉生物群落依靠化学自营维持生存与繁衍，构成了独特的生态系统，是对光合作用生态系统理论的一个挑战和补充，在生物学上有着重要的研究意义，对于揭示生命的起源与拓展生命的生存空间有着重要的学术价值，而且还孕育着广泛而重要的应用价值和商业前景，具体体现在新型医药开发、基因疗法、工业应用以及环境保护等方面。深海热泉生物将是人类最重要的基因资源宝库。     

Analysis and comparison of the tidal gravity observations obtained with LCR-ET20 spring gravimeter

Introduction The tidal variation signals of the solid Earth recorded with the modern measuring techniques can be used to provide effectively the means to cognize the Earths motion, deformation and structure character, especially to monitor the material motion in the Earths interior. In the recent 20 years, the distribution character of the global gravity field has made great progress since the continuous and deep theoretical studies in geophysics and geodesy domains. The successful manufactur…     

Paleolatitudes of the Kerguelen hotspot: new paleomagnetic results and dynamic modeling

The Kerguelen Plateau, a Large Igneous Province in the southern Indian Ocean, was formed as a product of the Kerguelen hotspot in several eruptive phases during the last 120 Myr. We obtained new paleolatitudes for the central and northern Kerguelen Plateau from paleomagnetic investigations on basalts, which were drilled during ODP Leg 183 to the Kerguelen Plateau-Broken Ridge. The paleolatitudes coincide with paleolatitudes from previous investigations at the Kerguelen Plateau and Ninetyeast Ridge (the track of the Kerguelen hotspot) and indicate a difference between paleolatitudes and present position at 49°S of the Kerguelen hotspot. We show that true polar wander, the global motion between the mantle and the rotation axis, cannot explain this difference in latitudes. We present numerical model results of plume conduit motion in a large-scale mantle flow and the resulting surface hotspot motion. A large number of models all predict southward motion between 3° and 10° for the Kerguelen hotspot during the last 100 Myr, which is consistent with our paleomagnetic results.     

3D shear-wave velocity structure of the Eifel plume, Germany

The Quaternary Eifel volcanic fields, situated on the Rhenish Massif in Germany, are the focus of a major interdisciplinary project. The aim is a detailed study of the crustal and mantle structure of the intraplate volcanic fields and their deep origin. Recent results from a teleseismic P-wave tomography study reveal a deep low-velocity structure which we infer to be a plume in the upper mantle underneath the volcanic area [J.R.R. Ritter et al., Earth Planet. Sci. Lett. 186 (2001) 7-14]. Here we present a travel-time investigation of 5038 teleseismic shear-wave arrivals in the same region. First, the transverse (T) and radial (R) component travel-time residuals are treated separately to identify possible effects of seismic anisotropy. A comparison of 2044 T- and 2994 R-component residuals demonstrates that anisotropy does not cause any first-order travel-time effects. The data sets reveal a deep-seated low-velocity anomaly beneath the volcanic region, causing a delay for teleseismic shear waves of about 3 s. Using 3773 combined R- and T-component residuals, an isotropic non-linear inversion is calculated. The tomographic images reveal a prominent S-wave velocity reduction in the upper mantle underneath the Eifel region. The anomaly extends down to at least 400 km depth. The velocity contrast to the surrounding mantle is depth-dependent (from −5% at 31-100 km depth to at least −1% at 400 km depth). At about 170-240 km depth the anomaly is nearly absent. The resolution of the data is sufficient to recover the described features, however the anomaly in the lower asthenosphere is underestimated due to smearing and damping. The main anomaly is similar to the P-wave model except the latter lacks the ‘hole’ near 200 km depth, and both are consistent with an upper mantle plume structure. For plausible anhydrous plume material in the uppermost 100 km of the mantle, an excess temperature as great as 200-300 K is estimated from the seismic anomaly. However, 1% partial melt reduces the required temperature anomaly to about 100 K. The temperature anomaly associated with the deeper part of the plume (250 to about 450 km depth) is at least 70 K. However, this estimate is quite uncertain, because the amplitude of the shear-wave anomaly may be larger than the modelled one. Another possibility is water in the upwelling material. The gap at 170-240 km depth could arise from an increase of the shear modulus caused by dehydration processes which would not affect P-wave velocities as much. An interaction of temperature and compositional variations, including melt and possibly water, makes it difficult to differentiate quantitatively between the causes of the deep-seated low-velocity anomaly.     

金沙江干热河谷土地荒漠化评价方法研究

什么样的退化土地才是荒漠化土地，土地荒漠化的发生发展以及程度和区别等问题的定量确定，至今有关报道甚少。干热河谷是我国西南地区特殊的生态环境类型，自然资源丰富，但土地荒漠化问题十分突出，这一现象的定量认识尤为重要。针对土地景观生态系统的复杂和模糊性，在建立评价指标的基础上，采用模糊综合评判的方法，对土地荒漠化程度进行定量评价，为荒漠化土地的预防和防治提供科学依据和决策支持。