2004年入冬后清远市首次低温霜冻分析

本文通过分析2004年12月5～14日清远市北部地区出现的大面积连续低温霜冻天气,发现低温的出现与850hPa的负变高和露点温度有一定的对应关系,霜冻出现和结束与环流形势密切相关。     

Mega-blowouts in Qinghai–Tibet Plateau: Morphology,distribution and initiation

Blowouts are wind-eroded landforms that are widely distributed in the north-eastern part in Qinghai–Tibet Plateau (QTP), China. These blowouts are thought to form in response to climate change and/or human activity but little is known about their morphodynamics. Using field surveys, remote sensing and geographic information system (GIS) spatial analysis, the distribution and morphology of blowouts are analysed and their initiation considered. Results show the QTP mega-blowouts are some of the largest in the world. The orientations of the trough shaped blowouts are parallel with the prevailing wind, but the saucer and bowl-shaped blowouts are influenced by bi-directional transport. Whilst regional patterns of blowout shape and size were observed to reflect the extent of aeolian sediments and wind regimes, the relationship between the different morphological parameters showed consistency. During initial stages of development, the length to width ratios of blowouts increase rapidly with area but after they reach a mega size this relationship stabilizes as blowouts widen. Initial luminescence dating shows that blowouts appear to have initiated ~100 to 500 years ago, coinciding with the Little Ice Age (LIA) climate event when northwest winds are known to have intensified. Further work is required to confirm this initiation period and establish the significance of mega blowouts for landscape degradation and human activities. © 2018 John Wiley & Sons, Ltd.     

地震波传播的微分几何描述

本文以复杂介质中的走向函数为基础,引入走时场的微分流形,从微分几何观点看,复杂介质中的射线方程即为流形上的测地线方程,复杂介质中的标量波动方程即为流形上的协变标量场方程,从而建立起复杂介质中地震波传播的微分几何描述,文中还讨论该方法在射线追踪,波场变换等方面的应用。     

铜矿岭不稳定斜坡类型识别与工程地质分区

高速公(铁)路路基、隧道和桥梁工程等常常因地质灾害的存在而影响正常使用,尤其是类型不明的不稳定斜坡,明确地质灾害类型是影响不稳定体治理方案的首要任务.以宜巴高速公路铜矿岭不稳定斜坡为研究对象,采用野外地质调查、工程地质分析和监测数据分析的方法,判明了铜矿岭不稳定斜坡类型.野外调查结果表明该不稳定斜坡上部为残坡积物,下部...     

风和台湾暖流引起东海沿岸上升流数值计算

运用三维数值模型,首先计算了夏季风和台湾暖流引起的东海沿岸上升流。结果表明,风和台湾暖流的作用都可产生顺岸呈带状分布的上升流,风生上升流在２０ｍ至３０ｍ水层速度较大,其值一般为１．０×１０－３ｃｍ／ｓ;而台湾暖流形成的上升流则在３０ｍ以下速度较大,其值在浙南和闽北一般为１．０×１０－３ｃｍ／ｓ,在舟山近海为０．５×１０－３ｃｍ／ｓ。此外,运用Ｅｕｌｅｒｉａｎ－Ｌａｇｒａｎｇｉａｎ方法数值探讨了东海沿岸上升流区海水的源地。逆追踪结果表明,潮因子和风因子对沿岸上升流的贡献都是局地的,即仅能将上升流区附近下层的海水带到沿岸上层;台湾暖流则可将台湾海峡北口的深层水带到闽浙沿岸上层,使闽浙沿岸出现低温、高盐水。     

北武夷篁碧矿区逆冲推覆构造及其与钼、铅-锌成矿作用关系

北武夷篁碧矿区出露走向北北东、倾向北西西的逆冲推覆构造。野外观察表明,推覆构造在形成过程中一方面错断了先期形成的辉钼矿（体）,另一方面其派生的北西西向张裂隙又控制了晚期铅锌矿体的分布。结合辉钼矿Re-Os同位素年龄（154Ma）、赋矿火山岩的SHRIMP锆石U-Pb年龄（138Ma,131Ma）和主要推覆构造断裂带中钾...     

Carbon dioxide emissions from the Three Gorges Reservoir,China

Carbon dioxide (CO₂) emission from the river-type reservoir is an hotspot of carbon cycle within inland waters. However, related studies on the different types of reservoirs are still inadequate. Therefore, we sampled the Three Gorges Reservoir (TGR), a typical river-type reservoir having both river and lake characteristics, using an online system (HydroCTM/CO₂) and YSI-6600v2 meter to determine the partial pressure of carbon dioxide (pCO₂) and physical chemical parameters in 2013. The results showed that the CO₂ flux from the mainstream ranged from 26.1 to 92.2 mg CO₂/m² h with average CO₂ fluxes of 50.0 mg/m² h. The CO₂ fluxes from the tributary ranged from ?10.91 to 53.95 mg CO₂/m² h with area-weighted average CO₂ fluxes of 11.4 mg/m² h. The main stream emits CO₂ to the atmosphere the whole year; however, the surface water of the tributary can sometimes act as a sink of CO₂ for the atmosphere. As the operation of the TGR, the tributary became more favorable to photosynthetic uptake of CO₂ especially in summer. The total CO₂ flux was estimated to be 0.34 and 0.03 Tg CO₂/year from the mainstream and the tributaries, respectively. Our emission rates are lower than previous estimates, but they are in agreement with the average CO₂ flux from temperate reservoirs estimated by Barros et al. (Nat Geosci 4(9):593–596, 2011).     

磷灰石固定水溶性铅离子研究进展

羟基磷灰石与天然磷灰石均能有效地固定水溶性铅离子,１ｇ羟基磷灰石或改性活性天然磷灰石除去水溶液中的铅离子量可以高达８００ｍｇ;其反应机理以磷灰石的溶解与铅的磷酸盐矿物的沉淀为主,伴有表面吸附作用。羟基磷灰石和改性活化天然磷灰石可用于含铅废水的处理,而性能良好的天然磷灰石在对铅污染水体、土壤及废弃物进行原地改良方面具有广阔的前景。     

一个新的铋亚碲酸盐矿物—平谷矿

平谷矿是在北京市平谷县一小型金矿氧化带中发现的一种新矿物。共生和伴生矿物有褐铁矿、孔雀石、磷氯铝矿、泡铋矿、自然金、银金矿、石英、方解石和白钨矿。通常呈粒状集合体出现，单体板柱状，极为细小（0．3～0．6μm），黄绿色，玻璃至金刚光泽。实测密度＝8．44g／cm3，计算密度8．64g／cm3。维氏硬度449～572kg／mm2，相当摩氏硬度5～6。反射率＝13．25％，折射率＞2．0，计算折射率为2．145，电子探针分析结果Bi2O379．56％、TeO220．17％，总和99．73wt％，化学式Bi5。8043Te2。1475O13理想式Bi6Te2O13。X射线粉晶分析主要强线3．146（100）（12）、2．841（80）（200）、2．694（20）（040）、1．695（20）（321）、1．956（10）（240）、1．631（10）（16），斜方品系，a＝0．5689（1），b＝1．0791、c＝0．5308（1）um，晶胞体积V＝0．3258um3，Z＝1。