电感耦合等离子体质谱法测定铅合金中的微量杂质元素镉和锡

铅合金中的镉和锡由于含量较低,国家标准方法均为单一元素分析,步骤繁琐,检出限高,难以达到理想的检出要求。本文建立了应用电感耦合等离子体质谱法(ICP-MS)测定铅合金中微量级(μg/g级)杂质元素镉和锡的分析方法。采用单一的低浓度硝酸溶解铅合金,用低温慢溶的方式使样品溶解更加完全,减少了多离子对仪器的干扰;通过铅基体匹配和加入酒石酸保证了标准与样品介质的一致性,同时避免了锡的水解;以~(103)Rh作为内标元素,~(111)Cd和~(118)Sn作为测量同位素克服了质谱干扰。方法检出限为镉0.05 ng/g、锡0.04 ng/g,比国家标准方法的检出限(1~6μg/g)低,精密度小于4%。该方法试剂用量少,减少了处理样品的复杂性,实现了合金中微量级元素的准确测定。     

Correction of the ionospheric distortion on the MARSIS surface sounding echoes

Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the Mars Express (MEX) spacecraft has made numerous measurements of the Martian surface and subsurface. However, all of these measurements are distorted by the ionosphere and must be compensated before any analysis. We have developed a technique to compensate for the ionospheric distortions. This technique provides a powerful tool to derive the total electron content (TEC) and other higher-order terms of the limited expansion of the plasma dispersion function that are related to overall shape of the electron column profile. The derived parameters are fitted by using a Chapman model to derive ionospheric parameters like n₀, electron density primary peak (maximum for solar zenith angle (SZA) equal 0), and the neutral height scale H.

Our estimated ionospheric parameters are in good agreement with Mars Global Surveyor (MGS) radio-occultation data. However, since MARSIS does not have the observation geometry limitations of the radio occultation measurements, our derived parameters extend over a large range of SZA for each MEX orbit.

The first results from our technique have been discussed by Safaeinili et al. [2007, Estimation of the total electron content of the Martian ionosphere using radar sounder surface echoes. Geophys. Res. Lett. 34, L23204, doi:10.1029/2007GL032154].     

山东省三级地下水监测站网建设思考

随着国家地下水监测工程的启动,国土资源部提出了国家、省、市新的三级地下水监测站网建设要求。该文介绍了各级地下水监测站网的基本概念、主要建设内容,各级地下水监测站网建设服务对象、基本要求,细化了各级地下水监测站网建设要求,规范了建设行动。     

Evidence for chemical evolution in spectra of high redshift galaxies

Using a sample of 57 VLT FORS spectra in the redshift range 1.37< z < 3.40 and a comparison sample with 36 IUE spectra of local ( ) starburst galaxies we derive CIV equivalent width values and estimate metallicities of starburst galaxies as a function of redshift. Assuming that a calibration of the CIV equivalent widths in terms of the metallicity based on the local sample of starburst galaxies is applicable to high-z objects, we find a significant increase of the average metallicities from about 0.16 Z _⊙ at the cosmic epoch corresponding to z ≈ 3.2 to about 0.42 Z _⊙ at z ≈ 2.3. A significant further increase in metallicity during later epochs cannot be detected in our data. Compared to the local starburst galaxies our high-redshift objects tend to be overluminous for a given metallicity. This revised version was published online in August 2006 with corrections to the Cover Date.     

非饱和砂土抗拉强度的试验研究

含水合物土的抗拉强度特性对含水合物地层的稳定评估具有重要意义。以黏质粉土为赋存介质,利用四氢呋喃(THF)合成含水合物土试样,在冷冻库中利用改进后的单轴拉伸装置研究了含水合物土单轴抗拉强度特性。试验结果表明水合物饱和度、试样干密度、细粒含量对含水合物土的抗拉强度存在明显影响。随着水合物饱和度的增加,抗拉强度呈现指数函数的增长趋势。干密度和细粒含量对抗拉强度的影响在不同的水合物饱和度情况下影响不同,在低水合物饱和度情况下,干密度和细粒含量的增加会使抗拉强度增强;而在较高的水合物饱和度情况下,抗拉强度则随着干密度和细粒含量增加而降低。此外,通过分析含水合物土的波速特性,建立抗拉强度与波速之间的经验关系式。这一关系式对采用声波来估算含水合物土试样的抗拉特性具有重要的参考意义。     

NUMERICAL STUDY ON DOMINATING FACTOR AND KEY AREA OF EL NINO CYCLE FORMATION*

A coupled model,which is employed to study the dominating factor and key area of El Nino cycle formation,consists of a dynamical ocean model and a statistical atmospheric model.The coupled model with seasonal forcing successfully reproduces the El Nino event cycle which exhibits quasi-regular oscillations with a preferred period of about 4 years.The results show that the heat content(HC) is transported between the eastern and the western tropical Pacific areas.The spatial distribution of HC anomalies for four phases of the whole cycle clearly shows a possible formation mechanism of El Nino.Experiments further suggest that sea surface temperature in the tropical Pacific and HC in the central tropical Pacific are the most important factors and the central tropical Pacific is the most important area for determining formation of El Nino cycle.     

福建及台湾海峡地震预警工程架构探索

福建及台湾海峡是海陆板块碰撞到板内地震活动过渡带 ,东侧毗邻台湾板缘地震带 ,西侧为福建内陆板内地震活动区。这是得天独厚的观测研究大陆边缘地震构造带强震活动及板块动力学的良好地域。当前 ,我国进入全面建设小康社会历史时期 ,为防御地震造成社会灾害 ,实现以人为本 ,防患于未然 ,势必需要建构一个实用化的地震预警工程及其机制。本文即是在对福建及台湾海峡近 30多年以来观测研究的基础上 ,提出应用现代空间技术、数字地震、计算机网络等技术架构地震预警工程与机制的一种设想。     

泥浆含砂率对桩基质量的影响

本文通过对泥浆中颗粒的沉降特性分析，从量上得出泥浆性能对泥浆中颗粒的悬浮携渣能力。泥浆是一流变性的流体，对泥浆性能的把握，应综合考虑，而不偏向于某个指标。提出了在实践中对泥浆的正确使用和泥浆性能取用的建议。     

Noril’sk–Talnakh Cu–Ni–PGE deposits: a revised tectonic model

The Norilsk mining district is located at the northwest margin of the Tunguska basin, in the centre of the 3,000×4,000 km Siberian continental flood basalt (CFB) province. This CFB province was formed at the Permo-Triassic boundary from a superplume that ascended into the geometric centre of the Laurasian continent, which was surrounded by subducting slabs of oceanic crust. We suggest that these slabs could have reached the core–mantle boundary, and they may have controlled the geometric focus of the superplume. The resulting voluminous magma intruded and erupted in continental rifts and related extensive flood basalt events over a 2–4 Ma period. Cu–Ni–PGE sulfide mineralization is found in olivine-bearing differentiated mafic intrusions beneath the flood basalts at the northwestern margin of the Siberian craton and also in the Taimyr Peninsula, some 300 km east of a triple junction of continental rifts, now buried beneath the Mesozoic–Cenozoic sedimentary basin of western Siberia. The Norilsk-I and Talnakh-Oktyabrsky deposits occur in the Norilsk–Kharaelakh trough of the Tunguska CFB basin. The Cu–Ni–PGE-bearing mineralized intrusions are 2–3 km-wide and 20 km-long differentiated chonoliths. Previous studies suggested that parts of the magma remained in intermediate-level crustal chambers where sulfide saturation and accumulation took place before emplacement. The 5–7-km-thick Neoproterozoic to Palaeozoic country rocks, containing sedimentary Cu mineralization and evaporites, may have contributed additional metal and sulfur to this magma. Classic tectonomagmatic models for these deposits proposed that subvertical crustal faults, such as the northeast-trending Norilsk–Kharaelakh fault, were major trough-parallel conduits providing access for magmas to the final chambers. However, geological maps of the Norilsk region show that the Norilsk–Kharaelakh fault offsets the mineralization, which was deformed into folds and offset by related reverse faults, indicating compressional deformation after mineralization in the Late Triassic to Early Jurassic. In addition, most of the intrusions are sills, not dykes as should be expected if the vertical faults were major conduits. A revised tectonic model for the Norilsk region takes into account the fold structure and sill morphology of the dominant intrusions, indicating a lateral rather than vertical emplacement direction for the magma into final chambers. Taking into account the fold structure of the country rocks, the present distribution of the differentiated intrusions hosting the Norilsk-I and Talnakh–Oktyabrsky deposits may represent the remnants of a single, >60 km long, deformed and eroded palm-shaped cluster of mineralized intrusions, which are perceived as separate intrusions at the present erosional level. The original direction of sill emplacement may have been controlled by a northeast-trending paleo-rise, which we suggest is present at the southeastern border of the Norilsk–Kharaelakh trough based on analysis of the unconformity at the base of the CFB. The mineralized intrusions extend along this rise, which we interpret as a structure that formed above the extensionally tilted block in the metamorphic basement. Geophysical data indicate the presence of an intermediate magma chamber that could be linked with the Talnakh intrusion. In turn, this T-shaped flat chamber may link with the Yenisei–Khatanga rift along the northwest-trending Pyasina transform fault, which may have served as the principal magma conduit to the intermediate chamber. It then produced the differentiated mineralized intrusions that melted through the evaporites with in situ precipitation of massive, disseminated, and copper sulfide ore. The Norilsk–Kharaelakh crustal fault may not relate to mineralization and possibly formed in response to late Mesozoic spreading in the Arctic Ocean.Editorial handling: P. Lightfoot     

国内外钼资源供需形势分析

全面、系统地建立钼矿石、钼矿粉分析方法,对钼元素研究开发和保障钼矿工业发展具有重要意义。目前多采用酸溶或碱熔样品后进行分析,其不足是测定钼含量的范围窄,消耗样品量大,还需使用大量酸碱,且受仪器限制,分析高含量钼时多需对样品溶液进行数次稀释,使分析步骤更加繁琐。发射光谱法则可避免上述问题,但用之准确分析高含量钼矿石钼矿粉尚有测试方法的瓶颈需要突破。本文研究通过内标元素、分析线对、缓冲剂配比、电流程序等环节的实验分析,建立了固体进样-交流电弧发射光谱法测定钼矿石中高含量钼的分析方法：优化样品与光谱缓冲剂质量比至1∶2,优化分析线对,截取曝光时间35s,采用以国家一级合成硅酸盐光谱分析标准物质和国家一级矿石标准物质组成的自研标准系列制作标准曲线,由全谱交直流电弧发射光谱仪自动扣除分析线和内标线背景后以对数坐标二次曲线拟合计算,使测定范围扩展为500～500800μg/g,检出限为27.38μg/g,相对标准偏差（RSD）为3.28%～8.30%,相对误差为-0.43%～0.73%。结果表明,本文方法在实现绿色分析的同时,在检出限相当、精密度合格的条件下,一次性分析高含量钼的上限从5%提高至50%。