Fate and transport of volatile organic compounds in glacial till and groundwater at an industrial site in Northern Ireland

Volatile organic compound (VOC) contamination of subsurface geological material and groundwater was discovered on the Nortel Monkstown industrial site, Belfast, Northern Ireland. The objectives of this study were to (1) investigate the characteristics of the geological material and its influences on contaminated groundwater flow across the site using borehole logs and hydrological evaluations, and (2) identify the contaminants and examine their distribution in the subsurface geological material and groundwater using chemical analysis. This report focuses on the eastern car park (ECP) which was a former storage area associated with trichloroethene (TCE) degreasing operations. This is where the greatest amount of volatile organic compounds (VOCs), particularly TCE, were detected. The study site is on a complex deposit of clayey glacial till with discontinuous coarser grained lenses, mainly silts, sands and gravel, which occur at 0.45–7.82 m below ground level (bgl). The lenses overall form an elongated formation that acts as a small unconfined shallow aquifer. There is a continuous low permeable stiff clayey till layer beneath the lenses that performs as an aquitard to the groundwater. Highest concentrations of VOCs, mainly TCE, in the geological material and groundwater are in these coarser lenses at ∼4.5–7 m bgl. Highest TCE measurements at 390,000 μg L⁻¹ for groundwater and at 39,000 μg kg⁻¹ at 5.7 m for geological material were in borehole GA19 in the coarse lens zone. It is assumed that TCE gained entrance to the subsurface near this borehole where the clayey till was thin to absent above coarse lenses which provided little retardation to the vertical migration of this dense non-aqueous phase liquid (DNAPL) into the groundwater. However, TCE is present in low concentrations in the geological material overlying the coarse lens zone. Additionally, VOCs appear to be associated with poorly drained layers and in peat <3.0 m bgl in the ECP. Some indication of natural attenuation as VOCs degradation products vinyl chloride (VC) and dichloromethane (DCM) also occur on the site.     

The Fate of High-Angle Dipping Slabs in the Subduction Factory: an Integrated Trace Element and Radiogenic Isotope (U, Th, Sr, Nd, Pb) Study of Stromboli Volcano, Aeolian Arc, Italy

The subaerial part of the Stromboli stratovolcano was builtup in the last 100 kyr through six periods of activity; theerupted magmas record the largest compositional variation ofall the Aeolian arc volcanoes (calc-alkaline, shoshonitic, andpotassic alkaline magma series). The trace element characteristicsof the less evolved magmas of each period of activity are coherentlycorrelated with their radiogenic isotope (Sr, Nd, Pb) composition,and are typical of volcanic arc rocks. In terms of U-seriesisotopes, samples from the different magma series have both²³⁸U and ²³⁰Th excesses, and this distinctive feature providesadditional constraints on source enrichment processes withinthe mantle wedge and on the mechanism of partial melting. Overallthe complete set of data demonstrates that the genesis of thedifferent magma series at Stromboli can be accommodated in amantle source that experienced two distinct enrichment processesby different parts of the subducting oceanic crust of the Ionianslab. The first was caused by supercritical liquids originatingfrom the basaltic and sedimentary parts of the subducting slabat >5 GPa and 900°C. The second was induced by aqueousfluids, again originating from the basaltic and sedimentaryparts of the slab, released from a shallower part of the subductedIonian slab (< 5 GPa and 800°C). U–Th disequilibriaconstrain the timing of the first metasomatic event (Stage I:supercritical liquids) at >435 ka, whereas the second event(Stage II: aqueous fluids) occurred at 100 ka. The high-angledip of the Ionian slab (70°) caused the superimpositionof the metasomatizing agents of the two enrichment processesin the same volume of the mantle wedge, explaining the occurrenceof such different magma series in a single volcanic edifice.The U–Th disequilibria provide evidence for dynamic meltingof the metasomatized mantle wedge combined with an ageing effectresulting from the restoration of secular equilibrium afterthe perturbation caused by the U-rich aqueous fluids of StageII. The trace element and radiogenic isotope (U, Th, Sr, Nd,Pb) signature of the mantle source of the magmas at Stromboliis thus dependent upon the amount of supercritical liquids andaqueous fluids released by the two components of the subductedslab, whereas the distinctive ²³⁸U and ²³⁰Th excesses of themagmas result from a combination of mantle ageing and time-dependentdynamic melting. The geochemical and radiogenic isotope signatureof the mantle source beneath Stromboli places important constraintson the isotopic polarity from Southern Latium to the Aeolianarc attributed to the effect of a HIMU mantle component followingeither lateral inflow of foreland mantle material or upwellingof a mantle plume in the centre of the Tyrrhenian basin. Ourgeochemical model demonstrates that the high ²⁰⁶Pb/²⁰⁴Pb ofthe putative ‘HIMU’ mantle component could be equallyformed during metasomatism of the pre-existing mantle wedgeby either the supercritical liquid (Stage I) or aqueous fluid(Stage II) released by the subducted altered basalt of the Ionianplate. KEY WORDS: radiogenic isotopes; U–Th disequilibria; mantle metasomatism; supercritical liquid; aqueous fluid; Stromboli     

台风暴雨矿渣型泥石流形成机制与动力特征——以兴宁乌石坑沟泥石流为例

受台风“尤特”登陆影响,台风暴雨直接激发兴宁乌石坑沟特大矿渣型泥石流灾害,物源巨大,潜在危害极大。笔者等通过现场调绘及室内试验,对本次泥石流的形成机制及动力特征进行研究,旨在为此类泥石流致灾机理及危害性评价提供借鉴。研究表明,其独特的流域地形特点为泥石流形成的基本因素,以沟道堆积物为主的丰富矿渣型物源是基础条件,高强度的台风暴雨是直接激发因素,与矿山开采、矿渣随意堆放等人为因素共同作用扩大了灾害规模。泥石流形成过程与动力特征为前期强降雨—崩滑碎屑流—矿渣型泥石流—台风暴雨—沟道堵塞雍高—溃决、规模放大。     

原位生成离子液体分散液液萃取-高效液相色谱法测定水样中的莠去津

本文引入绿色溶剂离子液体作为萃取剂,建立了超声辅助-原位生成离子液体分散液液微萃取水样中莠去津的方法。即处理5 m L水溶液样品,以80μL的[HMIM]Cl为萃取剂,加入400μL配对离子交换剂双三氟甲磺酰亚胺锂盐(Li NTf2),通过原位生成的疏水性离子液体[HMIM]NTf2,对水中莠去津进行液液微萃取,经辅助超声10 min后4000 r/min离心8 min,结合高效液相色谱测定莠去津。莠去津的检出限为0.01mg/L,方法线性范围为0.01~0.5 mg/L,加标回收率(100.4%~106.7%)显著优于直接离子液体分散液液萃取法(67%)。这种原位生成离子液体微萃取技术有望应用于更广泛的有机污染物分析检测中。     

X射线荧光光谱-X射线衍射-红外光谱联用技术鉴别锰矿与锰冶炼渣

鉴别锰矿与锰冶炼渣对于锰矿进口贸易和环境保护具有重要意义,由于锰冶炼渣与一些锰矿具有相似的元素组成,都含有锰和硅铝镁钙等杂质元素,仅从元素含量的高低无法准确将其鉴别。本文按国别收集我国主要进口锰矿及不同工艺的主要锰冶炼渣作为研究样品,应用X射线荧光光谱、X射线衍射及傅里叶变换红外光谱技术相结合,建立了锰矿与锰冶炼渣的鉴别方法。在元素组成上,锰冶炼渣的硅含量较高,水淬渣和空气冷却渣的钙含量较高。在物相上,锰矿的特征物相包括软锰矿、氧化锰、方锰矿、菱锰矿等;而锰冶炼渣因为经过冶炼的过程存在硅酸铁、锰橄榄石等特征峰,从而对样品属性进行鉴别。红外光谱显示,锰矿在600~400 cm~(-1)范围内有两个强吸收带,并单独或者同时在1420 cm~(-1)处有特征吸收峰;而锰冶炼渣在960 cm~(-1)左右有宽强吸收峰。本法建立了锰矿的物相谱图库及锰冶炼渣的物相特征,并充分利用红外光谱技术作了有力佐证,确定了锰矿及其冶炼渣的主要区别点。     

页岩气藏超低含水饱和度形成模拟及其意义

页岩气属于非常规天然气,资源丰富,开发潜力巨大。含水饱和度是控制致密气藏持续生产最关键的储层参数,然而现阶段对页岩气成藏中超低含水饱和度是否存在尚存在疑问。选取川渝地区页岩露头岩样,采用气驱法模拟了成藏过程中含水饱和度变化,结合川南页岩气储层地质特征,建立了生烃排驱的地质模型,提出了气携液的概念模型。结果表明,页岩气藏存在超低含水饱和度现象;页岩气成藏过程中大量生烃产生排驱效应与气携液作用,有利于页岩气储层超低含水饱和度的形成,气携液作用、裂缝和高温环境加速了含水饱和度降低;超低含水饱和度增加页岩气储层吸附能力,增大储层可流动孔喉范围,提高气相传输能力,但在工程作业过程中加大水相渗吸速率,强化水相滞留效应,使页岩气藏水相圈闭损害潜力更大。在页岩气有利区评价、气藏钻完井、开发过程中,须倍加重视超低含水饱和度这一客观事实和其衍生的工程作业问题。     

化学激发酸性矿渣粉胶砂性能试验研究

以28天最优配方激发酸性矿渣粉为胶凝材料进行试验,分析了质量浓度、灰砂比、减水剂掺量、搅拌时间4个因素对砂浆流动度、失水率、干缩率、抗压强度的影响规律,并且针对灰砂比这一因素将水泥与矿渣粉胶凝材料浆液性能进行了对比。最后选取了合适的比例进行正交试验来优化各因素组合,使砂浆综合性能达到最优。     

武汉地区建筑废弃泥浆泥水分离试验研究

针对武汉地区不同地层、不同工艺产生的建筑工程废弃泥浆,通过光谱仪分析了其主要化学成分,并通过过滤、真空抽滤、离心以及不同絮凝剂的正交试验,以上清液浊度和清液率为主要指标对废弃泥浆泥水分离效果进行评价。试验发现：废弃泥浆固相颗粒以有机质为主;采用过滤方式取得的清液浊度较低,但清液率较少;采用真空抽滤方式处理废弃泥浆可以获得较多的上清液;采用离心方式能处理除含特细颗粒外的多数废弃泥浆;正交试验表明阳离子絮凝剂（PAM）处理废弃泥浆效果较好。     

转炉高温熔渣显微结构研究

传统的炉渣岩相分析方法是在显微镜下观察其冷凝渣的岩相结构,并以此来推测该炉渣在高温下的行为。但炉渣在由熔融态逐渐冷却的过程中,会发生物理、化学变化,故用冷凝渣结构来反映炉渣高温状态是有缺陷的。为此,试用热台高温显微镜进行了炉渣高温显微结构研究,并与冷凝渣进行了对比。１　研究方法１－１　试验设备采用英国１２Ｄ型热台高温显微镜,进行了高温熔渣研究。该高温显微镜是以热电偶、发热体和样品支架为一体的微型高温炉为主体,ＰｔＲｈ热丝炉可迅速将约０－１ｍｇ试样加热到１６５０℃以上,并可利用放大５０倍的显微镜…     

河北山前平原地下水^32Si年龄初探

＾３２Ｓｉ是放射性同位素,半衰期约１４０ａ可以测定５０～１０００ａ地下水的年龄,本文用Ｆｅ（ＯＨ）３共沉淀法从天然水中提取ＳｉＯ２回收率可达３０％～９８％,然后提取和纯化＾３２Ｐ,将Ｈ３ＰＯ４溶液和Ｐｉｃｏ－ｆｌｏｕｒ＾ＴＭＬＬＴ混合制备计数溶液,用液体闪烁计数法测量中＾３２Ｐ的放射性,本底计数为４．８０ｃｐｈ,仪器效率为４５．３４％,然后用公式计算样品的＾３２Ｓｉ放射性浓度和地下水的＾３２Ｓｉ年