戈壁地区公路防沙措施防沙效应的风洞试验

 以穿越河西走廊西部戈壁荒漠的嘉峪关至安西一级公路为研究对象,基于风洞模拟试验,针对不同类型公路路基横断面和防护措施设计模型,采用粒子图像测速系统,研究模型的流场变化,进而探讨戈壁公路风沙危害形成机理及防沙措施。研究结果表明:①由于研究区内风沙活动以不饱和风沙流为主,携沙风对公路路基掏蚀、磨蚀严重,需要对路基边坡进行有效砌护;②为了在公路表面形成输沙通道,中央隔离带地表与行车路面应保持同一高度,隔离带采用空隙度大于30%的疏透型;③在公路两侧沙源丰富地段,公路边坡的坡角应小于40°,并且取消防洪沟,以防止沟内积沙;④在沙源丰富地区,公路两侧由外到内依次铺设草方格、覆盖砾石、设置积沙沟的防沙带,可以减少气流中的含沙量,阻止流沙上路,有效解决公路风沙危害问题。     

近6 ka以来科尔沁沙地东部气候变化记录

 根据科尔沁沙地东部TL剖面磁化率、有机质、化学元素等气候代用指标的变化特征和14C测年结果,分析和讨论了科尔沁沙地6 ka BP以来的气候变化过程。实验数据显示,高频磁化率、低频磁化率、有机质、Al2O3含量变化趋势基本一致,且峰值段对应古土壤层,谷值段对应风成砂层。依据气候代用指标的变化将6 ka BP以来科尔沁沙地气候变化分为3个阶段：Ⅰ.6.0～4.2 ka BP,气候暖湿,夏季风逐渐增强,并占主导,冬季风较弱,与全新世大暖期对应,但存在百年尺度的气候波动,其中：6.0～5.6 ka BP,5.6～5.4 ka BP,4.9～4.2 ka BP气候暖湿;5.6～5.5 ka BP,5.4～4.9 ka BP气候相对冷干。Ⅱ.4.2～1.3 ka BP,气候相对暖湿,与上一阶段相比夏季风有所减弱,但仍强于冬季风,其间也存在次一级波动,3.7～3.6 ka BP,3.4～1.3 ka BP,气候相对暖湿,4.2～3.7 ka BP,3.6～3.4 ka BP气候相对干冷。Ⅲ.1.3～0.65 ka BP以来,气候波动频繁,后期有向暖湿发展的趋势。总体而言,区域气候变化与全球具有较好的一致性。     

基于区位选择的中国区域发展差距研究

中国区域发展差距是区域经济学者关注的重要问题,并形成了多种解释。基于构造的经济活动区位选择模型,认为区位是形成中国区域发展差距的关键原因,接近中心的地区经济活动更为密集,而且由于聚集经济使得工人生产率以及工资水平更高。中国的东部地区靠近亚太经济中心,这一区位优势使东部地区吸引了更多经济资源,而西部的周边地区经济不发达,难以吸引经济资源,从而形成了二者发展水平间的差距。因此,西部要缩小与东部地区的差距,不仅取决于自身努力,也取决于其毗邻地区的经济发展水平。     

Extreme wind gust hazard in Australia and its sensitivity to climate change

For consideration of structural design of buildings and infrastructure in Australia, this paper presents hazard modelling and mapping of extreme wind gusts under the current climate and likely future climate change. Statistical and probabilistic approaches are applied to analyse the daily extreme wind gust data recorded between 1939 and 2007 at 545 anemometer stations around Australia. The estimated hazards are compared with the regional design wind speeds specified by the structural design standard, AS/NZS 1170.2:2011. Our results indicate that, under the current climate, structures in the areas on the west of and around Brisbane, Queensland and Newcastle, New South Wales, may be under higher gust hazard than they are designed for. Sensitivity study shows that these areas are also sensitive to the projected synoptic wind intensity changes. When subjected to ±20 % intensity change and ±50 % occurrence frequency change of tropical cyclones, the northwest coast of Western Australia, the northern part of Northern Territory, and the northeast coast between Cairns and Townsville, Queensland, will experience around ±10 m/s changes in extreme wind gust speeds of 500-year return period.     

Public perception of climate change in China: results from the questionnaire survey

Based on the questionnaire survey, this paper analyzes China’s public perception of climate change in terms of several influence factors and some empirical findings are obtained. We find that some respondents are willing to take individual actions to address climate change, and they pay more attention to climate change or approve that climate change does harm to residents and society; meanwhile, they tend to have confidence in the government to deal with climate change or believe that fiscal and taxation policies are the effective policy measures. However, there are also other respondents unwilling to take actions and argue that climate change proves the natural consequences. Thus, in order to motivate the public to take actions, the paper suggests that the government should widespreadly disseminate relevant knowledge about climate change to the public and guide the work to address climate change and adopt proper fiscal and taxation policies.     

川西龙泉山西坡更新世泥石流的发现及其意义

在川西地区龙泉山西坡首次发现了第四纪泥石流沉积。泥石流沉积相组合为AA1B、AA1C、AA1,反映泥石流为洪积扇扇中沉积组合,具有粘性泥石流的沉积特征。ESR测年及孢粉化石组合特征表明泥石流沉积于早-中更新世温暖湿润的气候环境下。龙泉山泥石流的形成反映了龙泉山早-中更新世之交的构造隆升,以及四川盆地盆地期夷平面的解体,是对早-中更新世之交青藏高原的隆起、季风的加强、暴雨式降水出现的沉积响应,对于研究四川盆地西部及青藏高原东缘第四纪构造运动及古气候特征具有重要的意义。     

Accumulation of heavy metals in the lacustrine sediment of Longgan Lake, middle reaches of Yangtze River, China

Spatial and temporal distribution of heavy metals (Chromium, Copper, Nickel, Lead, and Zinc) in the sediment of Longgan Lake, middle reaches of Yangtze River, China were analyzed to discuss their enrichment characteristics and history in combination with geochronological data and to identify anthropogenic effects. The results showed that the enrichment state of heavy metals was higher in the western versus eastern lake area, although their concentrations behave in the opposite case, which demonstrated that stronger human activities existed in the western lake catchment. The enrichment history of heavy metals pointed out that prior to 1950, the enrichment state was lower in the ambient lake areas illustrating the natural effect on the lake; thereafter the human activities in the catchment enhanced markedly causing an increasing heavy metal enrichment. The increase of heavy metal enrichment in the 1970s occurred in the central lake areas. The temporal difference between the ambient and central areas elucidated that the heavy metal accumulation might be buffered by the lake before they entered the sediment. Correlation analysis revealed that there was a significant correlation between heavy metals in the sediment suggesting their similar sources. Heavy metals were distinctly related to aluminum, calcium, lithium, iron, and organic matters, which could denote their forms in the sediment.     

冈底斯明则-程巴斑岩-夕卡岩型Mo-Cu矿床成矿时代与含矿岩石成因

冈底斯东南缘克鲁-冲木达矿带以发育渐新世斑岩-夕卡岩型Mo-W-Cu成矿作用而有别于冈底斯中新世斑岩-夕卡岩型Cu-Mo-Au矿带,但是对渐新世成矿岩石类型及成因以及渐新世与中新世斑岩成矿作用存在差异的原因尚不清楚,严重制约了该带矿产资源潜力评价.为此,本文选择矿带内程巴斑岩型Mo矿床及明则夕卡岩型Cu矿床开展了成岩与成矿年代学及含矿岩石成因研究.明则矿区与夕卡岩矿化有关的二长岩的结晶年龄为30.4±0.6Ma,表明夕卡岩矿化时代约30Ma,这与程巴斑岩型Mo矿床矿石中辉钼矿Re-Os同位素分析所揭示的约30Ma矿化时代一致.明则二长岩的SiO2含量为55％ ～57％,K2O含量为2.7％ ～5.0％,属于钾玄岩,具有较高的MgO含量(3.5％～6.9％)、Mg#值(57.6～67.2)以及相容元素含量(Cr =34×10-6 ～379×10-6;Ni为48×10-6～116×10-6).而程巴花岗闪长岩的SiO2含量为65％ ～ 67％,K2O含量为3.2％～4.1％,属于高钾钙碱性岩,具有较低的MgO含量(1.7％～2.1％)、Mg#值(49.5～51.1)以及相容元素含量(Cr =20×10-6～39×10-6;Ni为16×10-6 ～25×10-6).二长岩和花岗闪长岩均显示富集轻稀土元素与大离子亲石元素,亏损高场强元素,具有弱的Eu负异常,但二长岩的REE含量明显高于花岗闪长岩,且具有较低的Sr/Y比值(24 ～49),后者Sr/Y比值为54～68.两种岩石均具有类似的Hf同位素组成,二长岩的εHf(t)值为+2.8～+6.8,花岗闪长岩εHf(t)值为+4.2～ +6.1.综合分析表明,二长岩是受大洋板片流体交代的富集岩石圈地幔部分熔融的产物,而花岗闪长岩是增厚的新生下地壳部分熔融的产物,二者在形成过程中可能发生了幔源镁铁质岩浆与壳源长英质岩浆的混合作用,这种壳幔相互作用导致区域斑岩-夕卡岩型Cu-Mo矿化,但由于该区隆升剥蚀强烈,上部的斑岩型Cu矿体基本被剥蚀而没有保存下来,因此现今表现为斑岩型Mo矿床.     

华北深部岩石圈存在弱的新元古代热活动的同位素年代学信息：证据及意义

人们普遍认为华北区别于华南的主要特征在于缺少广泛的新元古代岩浆活动,但原因是什么还不清楚。本文汇总了华北四个地区深源岩石包体中有这样同位素年龄的结果,并就它们所反映的华北当时在Rodinia超大陆裂解中心的位置和可能的岩石圈厚度进行了讨论。这些深源岩石包体分别是辽宁复县古生代金伯利岩中的基性麻粒岩、河北涉县碳酸岩化金伯利岩中石榴石辉石岩、河南信阳中生代火山岩中的橄榄岩及河北汉诺坝新生代玄武岩中橄榄岩。所记录的新元古代年龄信息包括:复县基性麻粒岩锆石0.61Ga的下交点年龄,涉县石榴石辉石岩全岩-单矿物的0.76GaSm-Nd内部等时年龄、信阳橄榄岩锆石的新元古代(>0.64Ga)年龄以及汉诺坝橄榄岩硫化物0.9～0.6Ga的Re-Os年龄。与华南广泛发育新元古代岩浆活动不同,华北有限的新元古代年龄信息(包括地表出现的)可能反映着它们当时在Rodinia超大陆的位置有所不同,即华南更靠近于超大陆裂解的中心、而华北可能远离该中心(如边缘)。位置的差别也预示着当时华南岩石圈的可能比较薄、而华北具巨厚的岩石圈。因此,我们认为弱的热事件和巨厚的岩石圈可能是造成华北新元古代热活动不明显的原因。