硝酸-氢氟酸酸溶电感耦合等离子体质谱法测定黑钨矿单矿物中稀土元素

黑钨矿单矿物通常混入铬、钙、镁、钴、钪和稀土等元素,属于富含稀土型矿物,准确测定黑钨矿中的稀土元素对判定黑钨矿矿床的成因相当重要。黑钨矿单矿物样品经硝酸-氢氟酸高压密闭溶解,蒸干除去氢氟酸,以硝酸提取使稀土元素进入溶液,钨则以钨酸的形式从溶液中沉淀而分离,采用电感耦合等离子体质谱法测定稀土元素的含量。用Rh、Re双内标校正,有效地降低了分析信号漂移对分析结果的影响;Ba对153Eu干扰、Pr、Ce对157Gd干扰,采用分析软件在线扣除。该方法消除了钨基体元素的干扰,复溶沉淀实验表明残留稀土相对量小于10%,稀土元素的测定值与过氧化钠碱熔法的结果相符。方法加标回收率为94.2%～104.0%,相对标准偏差小于10%,检出限小于0.026μg/g。方法简便,准确度高,检出限低,适用于黑钨矿单矿物的分析。     

华南富铀花岗岩和产铀花岗岩特征

文章简要叙述了我国南方5省(区)富铀花岗岩和产铀花岗岩概况,详细讨论了产铀花岗岩的主要特征:断裂构造发育,蚀变作用非常强烈,经常有二云母花岗岩出现,中基性和酸性脉岩比较发育。正是这些特征,决定了它们产出铀矿床的能力。     

A study on resonance Rayleigh scattering spectra of Humic Acid (HA)

This paper deals with the influences of pH, acidity and ionic intensity of the solutions on the resonance Rayleigh scattering spectra and fluorescence spectra of humic acid. When the pH value is low and the acidity and ionic intensity are high, the resonance Rayleigh spectra and fluorescence spectra both show a tendency of increasing, though the former’s intensity is much higher. In combination with the transmission electron microscope data, the factors leading to the occurrence and enhancement of the resonance Rayleigh scattering spectra of humic acid were explored. It is considered that particle enlargement caused by aggregation, the increase of heterogeneity, the increase of hydrophobility, the formation of interface, etc., are the factors leading to the occurrence and enhancement of the resonance Rayleigh scattering spectra of humic acid. As the intensity of the resonance Rayleigh scattering spectra of humic acid is much higher, resonance Rayleigh scattering spectroscopy can be used as a newly developed spectrum technology, which is more sensitive and simpler, to study humic acid and its complicated behaviors.     

农业活动对岩溶作用碳汇的影响:以重庆青木关地下河流域为例

以受农业活动影响强烈的重庆青木关地下河流域为研究对象,利用CTDP300多参数水质自动记录仪、WGZ-1型光电数字水位计、HOBO小型气象站在线自动监测电导率、水位以及降雨等数据,并获取流域耕地面积数据,于2010年分月采集地下水样,分析常规水化学和地下水溶解无机碳δ13C,初步探讨流域农业活动对岩溶作用过程和碳汇的影响,发现农业活动对岩溶作用过程产生明显的影响,进而影响到岩溶地质碳汇。地下水水化学以及地下水δ13CDIC值证实了流域地下水DIC是碳酸、硝酸和硫酸共同溶蚀碳酸盐岩的产物;每月碳酸溶蚀碳酸盐岩产生DIC占地下水中总DIC的比例在55.53%～81.25%之间,雨季(62.98%)普遍低于旱季(74.86%);碳酸溶蚀碳酸盐岩产生的DIC的量为14.67×106mol/a,其中岩溶作用产生的净CO2汇量为7.335×106mol/a,而硝酸和硫酸溶蚀碳酸盐岩产生的DIC总量为7.48×106mol/a,约占地下水中总DIC的33.8%,单位面积耕地上硝酸和硫酸溶蚀碳酸盐岩产生DIC的强度为1.89×106mol/(km2.a)。人类活动引入的硝酸和硫酸参与碳酸盐岩的溶解并改变了区域碳循环。     

Heavy-metal loadings related to urban contamination in the Kooloonbung Creek catchment,Port Macquarie,New South Wales

Urbanisation and industrial development lead to contamination of estuaries and streams with dispersed loadings of heavy metals and metalloids. Contributions of these elements also occur from natural sources. This study provides baseline geochemical data on the respective natural and anthropogenic inputs of Cu, Pb, Zn, Cd, As, Sb, Cr, Ni, Mn and S to estuarine, fluvial and wetland sediments, and adjacent soils, in the Kooloonbung Creek catchment that drains the Port Macquarie urban area in north coastal New South Wales. There have been anthropogenic additions of Cu, Pb, Zn and As from dispersed urban sources at Port Macquarie, but they are restricted to the local catchment and do not impact on the adjacent Hastings River estuary. The most contaminated sediments display enrichment factors up to 20 × for Cu and Pb, 9 × for Zn and 5 × for As relative to local background values. However, only one value (for Pb) exceeds National Water Quality Management Strategy interim sediment quality guideline (high) values. On the other hand, sediments and local soils are commonly strongly enriched in Cr, Ni and Mn, reflecting adjacent ultramafic and mafic rock substrate and lateritic regolith. Concentrations of Cr and Ni are commonly well above interim sediment quality guideline (high) values for sediments, but are in mineralogical forms that are not readily bioavailable. Sediment and soil quality guideline values consequently need to recognise natural enrichments and the mineralogical siting of heavy metals. Although dissolved concentrations of heavy metals in stream waters are commonly low, there is evidence for mobility of Cu, Zn, Fe and Al. Parts of the Kooloonbung Creek wetland area lie on sulfidic estuarine sediments (potential acid sulfate soils). Experimental oxidation of uncontaminated and contaminated sulfidic sediments leads to substantial dissolution of heavy metals under acid conditions, with subsequent aquatic mobility. The results warn about disturbance and oxidation of potential acid sulfate soils that have been contaminated by urban and natural heavy-metal sources.     

Electron spin resonance dating of Quaternary bone material from Tasmanian caves—A comparison with ages determined by aspartic acid racemization and C14

Abstract

Fourteen bone samples are analysed to test the usefulness of equivalent dose (ED) determinations by electron spin resonance (ESR) as a rapid method of determining relative age and making an estimate of absolute age. ED values are compared with eight aspartic acid dates and two C¹⁴ dates. The latter are dates on charcoal found in close association with bone at archaeological sites. For samples less than 25 000 years old an excellent correlation is obtained when ED values are compared with dates obtained by the other two methods. The relationship suggests that ED values can be converted to estimates of bone age by assuming a mean annual dose rate of 0.1 rad/yr. Age determinations provide little evidence to support earlier suggestions that elements of the Late Pleistocene megafauna survived until the end of the Pleistocene. Bone material at some sites in the‐Florentine Valley and near Montagu appears to be much older than had previously been believed. Only one site (Main Cave, Montagu) containing megafaunal elements appears to be terminal Pleistocene in age but the possibility of reworking of megafauna material from nearby older sites cannot be excluded. ESR dating has considerable potential as an exploratory dating tool but can only be applied to dense, unaltered bone samples. Attempts to analyse five samples from Kutikina Cave in Western Tasmania were unsuccessful because of post‐depositional contamination of the bone.     

降尘矿物在柠檬酸中的溶出顺序研究

针对自然降尘进行的物相、成分分析表明该降尘的物相组成非常复杂,以石英、方解石、钠长石、白云石、云母为主要物相成分。为探讨降尘中矿物在有机酸中的溶解情况,进一步揭示其对人体的危害程度。本文以西宁降尘为研究对象,并选择柠檬酸为代表有机酸,分别用XRD、FTIR及ICP-AES等方法对柠檬酸处理前后降尘的残余固体及反应上清液进行分析。结果表明,降尘中方解石在经柠檬酸作用10 min后完全溶解,白云石在16 h内基本溶解完全,根据红外分析结果,Si—O、Al—O结构未发生明显破坏。然而,溶出元素结果显示,Al、Si的溶出量随着溶解时间的增长而缓慢增加,说明柠檬酸对Si—O四面体及Al—O八面体也造成了一定的破坏作用。通过分析降尘中3种难溶矿物在相同条件下的溶解速率可以得出,在整个溶解过程中,钠长石的溶解速率高于绢云母,而石英的溶解速率在不同的溶解时间有着较大的差异。根据3种纯矿的溶解速率推断三者的溶解顺序,钠长石明显先于云母溶解,石英的溶解先后顺序还有待进一步研究。通过降尘及纯矿在柠檬酸中溶解过程中不同时刻的元素溶出比例及矿物溶出速率可以得出除石英外4种主要矿物的溶解顺序为:方解石,白云石,钠长石,绢云母。     

乌东德水电站水垫塘边坡雾化雨入渗数值分析

高坝泄洪雾化雨入渗是影响其水垫塘边坡稳定的关键因素之一。为分析乌东德水电站水垫塘边坡受泄洪雾化雨影响程度,选取水垫塘边坡典型断面,建立二维非饱和、非稳定渗流计算模型,采用有限元法模拟泄洪雾化雨入渗过程,分析雾化雨入渗条件下坡体饱和区范围及压力水头的变化规律,同时对比研究坡面防护措施的效果。结果表明,对于坡体内部渗透性上强、下弱的部位,随着入渗补给量的持续增加,在阻水部位压力水头会逐渐升高;当坡面采取弱透水材料防护后,可显著减少坡面雾雨入渗量,从而显著降低雾化雨入渗对坡体渗流场的影响     

降雨入渗非饱和黏土边坡稳定性的极限平衡条分法研究

考虑非饱和黏土边坡的基质吸力和渗流力,根据水位线位于滑面上、下的临界平衡状态,分别建立了滑体条块极限平衡状态下力和力矩平衡式,获得了降雨条件下非饱和黏土边坡稳定性的极限平衡条分法计算式。通过试验、参量变换以及作用力的位置关系可以确定相关参量,并采用数值计算求解临界平衡状态下滑体条块的相互作用力系数和非饱和边坡安全系数。案例结果表明：考虑渗流力时的非饱和黏土边坡安全系数比不考虑渗流力的安全系数降低约13.8%,且考虑渗流力作用的条间力作用系数变化率明显大于不考虑渗流力的结果;当降雨强度超过一定值时,坡面径流很快形成,边坡出现不稳定的时间基本相同。     

黏土颗粒间液桥从形成至断裂时毛细力的演化规律

通过土颗粒间形如液桥的水分毛细力认识和解释非饱和土的持水特性日趋为土力学界所关注。为研究黏土颗粒间液桥毛细力的演化规律,将黏土颗粒其简化为一对平行的片状颗粒,不考虑黏土颗粒表面的粗糙度。以Young-Laplace方程为基础,推得表征黏土颗粒间液桥毛细力关于固-液接触角和液桥体积的无量纲表达式;再令该无量纲表达式为0,绘制出固-液接触角与无量纲液桥体积的关系曲线,将1/3＜vLB＜1范围划分为液桥的断裂区、形成区和消失区,这种分区方法对描述黏土样在毛细阶段和吸附阶段的持水特性至关重要。最后,分析了液桥形成时毛细力与液桥体积和固-液接触角的关系,结果表明：当固-液接触角一定时,液桥的毛细力随其体积增大呈递增趋势,而当液桥体积一定时,其毛细力随固-液接触角增大呈先增后减的趋势。