额尔齐斯金矿带岩金矿床成矿特征浅析

额尔齐斯金矿带是我国阿尔泰地区一条重要的金矿带,成矿地质条件优越,通过对多拉纳萨依、赛都、阿克塔斯和科克萨依4处典型金矿床的对比研究,总结了带内金矿床的基本特征并探讨了其成矿环境,认为在晚古生代造山带后碰撞伸展构造环境下,壳幔混源成因的花岗岩类岩脉为金成矿的主要物质来源,韧性—脆韧性构造变形是成矿的必要条件,韧性剪切—岩浆耦合成矿作用是金矿床成矿的关键,控制着金矿体的形成与产出。     

广东河台金矿滑痕线理与金矿体的关系及成矿意义

为了确定河台金矿的成矿动力学机制,文章研究了河台金矿滑痕线理与金矿体的关系。研究表明,两组滑痕线理均与金矿体有伴生关系;滑痕线理的两组侧伏角(10°~35°和42°~70°)与金矿体的两组侧伏角(20°~29°和45°~70°)一致;可能与滑痕线理形成有关的两组时间(187~192Ma和(141±6)~(157.1±1.0)Ma)与金矿体的两组形成时间(169~(175±4.3)Ma和(121.9±14.1)~(152.5±3.1)Ma)一致。以上研究表明,滑痕线理与金矿体有成因联系。结合前人研究成果,提出河台金矿沿滑痕线理发生滑动的减压过程中,很可能引发含金热液沿滑动方向的泵吸作用与减压沸腾成矿作用,进而决定了滑动方向控制了金矿体的延伸方向。脆—韧性剪切成矿期缓侧伏角的滑动作用(10°~35°)控制了缓侧伏角的矿体(20°~29°);热液成矿期陡侧伏角的滑动作用(42°~70°)控制了陡侧伏角的矿体(45°~70°)。     

陕西石泉—旬阳地区金矿床控矿因素与成矿模式

陕西石泉—旬阳地区是重要的金矿聚集带。文章以长沟和黄龙矿区为例,阐述了研究区矿床地质特征,重点分析了矿区构造、赋矿围岩等控矿因素,探讨了云煌岩脉与成矿的关系,认为韧性剪切带是区内矿体的重要控矿条件。研究区金矿床含金石英脉中石英流体包裹体均一温度集中于160~280℃之间,表明为低-中温成矿;富含金的黄铁矿Rb-Sr等时线年龄为(208±0.88)Ma,表明成矿时代为印支晚-燕山早期,该期的推覆剪切构造控制本区金矿形成。在上述综合研究的基础上,初步建立该区金矿床的成矿模式。     

新疆阿勒泰赛都金矿含金石英脉锆石U-Pb年龄及其地质意义

新疆阿勒泰南缘赛都金矿是典型的大型韧性剪切带型金矿。采用原位激光剥蚀同位素质谱(LA-ICP-MS)对赛都金矿含金石英脉中锆石定年,获得含金石英脉的形成年龄为310±3Ma,结合前人报道相关年代学资料,表明赛都金矿经历了三期主要构造-热液活动-成矿作用,发生的时间分别是310Ma、290Ma和270Ma左右。这一研究结果不仅准确地确定了赛都金矿的成矿时代和成矿阶段,而且对阿勒泰南缘额尔其斯构造带的演化提供了重要的新资料。     

东天山西凤山金矿花岗岩锆石U-Pb年龄、地球化学及其对成岩成矿时代的限定

为探讨西凤山金矿岩浆活动与成矿作用关系,对赋矿花岗岩类岩体(脉)(花岗岩、花岗斑岩、石英斑岩)分别进行了LA-ICP-MS锆石U-Pb同位素定年,获得加权平均年龄为(329.5±4.3) Ma、(324.6±4.6) Ma和(320.0±4.0) Ma,成岩时代为晚石炭世。地球化学表明,花岗岩具有富硅、略富铝,富钠低钾特征,属于钙碱性-高钾钙碱性、过铝质系列,具有Ⅰ型花岗岩特征。稀土元素配分曲线为平缓型,轻重稀土元素分馏明显,负Eu异常,微量元素富集Rb、Th和K,亏损Nb、Sr、P。综上所述,岩体形成于哈萨克斯坦-准噶尔板块与塔里木板块碰撞造山环境,成岩时代(329～320 Ma)早于成矿时代(272 Ma);相应成矿作用与康古尔韧性变形带的变形过程相耦合,具有韧性剪切带型金矿的特点。     

新疆阿克塔斯金矿地球物理特征及物探找矿方法技术组合

新疆富蕴县阿克塔斯金矿床,位于额尔齐斯深大断裂南侧,属额尔齐斯多金属聚矿带,文章通过对新疆富蕴县阿克塔斯金矿区的高精度磁测资料的处理解译,初步建立了宏观的矿区构造格架,利用激电中梯工作圈定了硫化物富集地段,并根据激电测深工作确定了有利的找矿部位,通过钻探验证,在激电异常部位发现了金矿,取得了良好的找矿效果。     

粤东金坑锡铜多金属矿区花岗岩锆石U-Pb年龄和辉钼矿Re-Os年龄及其地质意义

广东揭西县金坑铜锡多金属矿床位于粤东地区西北部莲花山断裂带南西段,是粤东锡铜多金属成矿带近年来发现的一处中—大型铜锡铅锌多金属矿床。采用LA-ICP-MS锆石U-Pb法和辉钼矿Re-Os法对矿区与成矿有关的细粒花岗岩及与锡石共生的辉钼矿进行定年,获得该矿床成岩年龄为(141.0±0.3)Ma,辉钼矿Re-Os同位素年龄为(141.3±1.0)Ma,两者年龄接近,表明成岩成矿关系最为密切。并结合细粒花岗岩主微量元素分析结果表明细粒花岗岩具有高硅富碱特点,属于高分异的I型花岗岩,这种岩浆演化末端产物细粒花岗岩有利于成矿金属元素富集,为本区成矿提供巨量的物源与热源。结合成岩成矿年龄研究与主微量分析,初步认为成矿地质体为早白垩世细粒花岗岩,并探讨该矿床的成因及其成矿动力学背景。     

广东金坑铜锡铅锌矿床成矿地质体研究

金坑铜锡铅锌矿区位于广东莲花山断裂带南西段,为中型热液充填交代铜锡铅锌矿床。文章在综合前人大量研究成果资料基础上,从成矿地质体与成矿的时空关系、物质来源方面进行系统分析研究。主微量元素与Hf同位素表明细粒黑云母花岗岩为高分异的I型花岗岩,并为成矿提供了巨量的物源和热源;硫、铅、氢氧稳定同位素证明成矿物质来源于深源岩浆,成矿流体以岩浆水为主并混入部分大气水,成矿环境为低盐度、中高温;岩浆岩LA-ICP-MS锆石U-Pb定年发现,细粒黑云母花岗岩成岩年龄为(141.0±0.3)Ma,矿床中与锡石毒砂共生的辉钼矿进行Re-Os同位素定年发现,成矿年龄为(141.3±1.0)Ma;由此初步认为该区成矿地质体为早白垩世细粒黑云母花岗岩。     

阿尔金断裂北侧英格里克韧性剪切带地质特征、锆石U-Pb年龄及其对加里东运动时限的讨论

阿尔金断裂带是中亚大陆内部、出露于青藏高原北部边缘的一条重要的走滑断裂带,为古生代经历过陆壳俯冲碰撞而形成的高压-超高压变质岩带。笔者在阿尔金断裂北侧发现了近东西向分布的英格里克韧性剪切带,这其中发育有大量韧、脆韧性变形构造,对其进行岩石学、运动学及年代学研究可为阿尔金断裂带研究提供一定依据,也为了解中国西部地区构造发展史提供了参考。通过岩石学分析,韧性剪切带内卷入岩石可分为2种,一是早期地质体经裂解作用形成的大型岩块,如新太古代-古元古代石英片岩岩块、长城纪大理岩岩块、蓟县纪角闪岩岩块和震旦纪角闪岩岩块,又有小型大理岩岩块、角闪岩块;二是经强烈挤压形成的基质,如糜棱岩化角闪岩、石英片岩、含炭质绿泥片岩,二者中"网结状构造"。在剪切带内发现有剪切透镜体,长英质条带,强直片麻理,鞘褶皱、紧闭同斜褶皱,左行不对称褶皱、石榴子石残斑、斜长石残斑。通过观察薄片可发现岩石中普遍发育有σ、δ型旋转碎斑、S-C组构,"云母鱼""长石鱼""拉丝"状石英,波状消光、亚晶粒旋转重结晶及核幔构造,眼球状长石斑晶形成"旋转雪球构造",显示两期变质事件的石榴子石的环带状构造,石榴石变斑晶的斜长石、石英冠状边。在韧性剪切带中识别出韧性剪切褶皱、糜棱岩带(韧性剪切带)和脆性断裂三期构造,分别代表了构造期次的早晚。应用LA-ICPMS锆石U-Pb定年法对3件样品进行分析,年龄峰值分别为1850~1950 Ma、900~1100 Ma和300~600Ma;1450~1550 Ma、950~1150 Ma和400~500 Ma;550~650 Ma。由此可确定英格里克韧性剪切带形成于加里东运动早期,为陆壳俯冲产物,并经受了多期次构造运动。     

南秦岭陕西酒店金矿区闪长岩脉时代、脆—韧性剪切带与成矿关系探讨

酒店金矿区位于陕西省安康北部金矿田西段,区内闪长岩脉、脆—韧性剪切带发育。目前该区内已发现同类型金矿床10余处。文章针对酒店金矿床中出露的闪长岩脉利用(LA-ICP-MS)进行锆石U-Pb同位素测年,其年龄值为(187. 5±3. 8) Ma,时代为早侏罗世。结合区内印支晚期—燕山早期脆—韧性剪切带与金矿化关系,认为该地区闪长岩脉中不含金,仅为金元素富集提供了有利的物理化学环境。金矿(化)体多产于闪长岩脉上、下盘叠加同时期脆—韧性剪切带形成的褶皱片岩中。     

质子低场核磁共振技术表征建筑石膏水化进程

基于溶解-析晶理论，根据X射线衍射和热重分析结果，将建筑石膏的水化进程划为4个水化阶段，并利用质子低场核磁共振技术研究了不同水膏比m_W/m_G和聚羧酸系减水剂(PCE)掺量下，新拌浆体横向弛豫时间T₂分布、T₂加权平均值■与主峰峰面积S_main随水化时间的变化规律.结果表明：■和S_main的变化趋势与水化阶段均具有良好的相关性；增大m_W/m_G可以使建筑石膏水化阶段出现的时间提前，而掺加PCE则对建筑石膏有明显的缓凝作用.     

不同构造环境花岗岩类的Na2O和K2O含量变化特征

结合花岗岩类的构造环境,通过对大量的岩石地球化学数据统计分析,总结了不同类型花岗岩的Na_2O和K_2O的含量变化,认为不同构造类型花岗岩的Na_2O和K_2O的含量变化可以用鲍文反应序列来解释。在一个构造演化越到晚期,岩浆分异程度越高,形成的花岗岩含K矿物越来越多,K_2O含量越高,Na_2O含量越低,反之,形成的花岗岩类K_2O含量越低,Na_2O含量越高。因此,可以认为,在早期大陆裂谷期由于岩石圈壳幔作用强烈,花岗岩分异程度中等,Na_2O含量略小于或约等于K_2O;到大洋形成时期,洋中脊出现,岩浆分异的程度应该非常低,Na_2OK_2O;收缩环境下形成的花岗岩分异程度较低,因此,岛弧环境的花岗岩Na_2OK_2O;大洋闭合陆陆碰撞环境形成的花岗岩分异程度适中,Na_2O≈K_2O;造山环境的花岗岩分异程度较高,Na2_O﹤K_2O。花岗岩的Na_2O和K_2O的含量变化及Na_2O/K_2O值基本可以反映花岗岩的构造环境。     

Spatial distribution of radionuclides in soil around a coal-fired power plant: 210Pb, 210Po, 226Ra, 232Th, 40K emitted with the fly ash and 137Cs from the worldwide weapon testing fallout

To determine the effect of airborne emissions of radionuclides from coal-fired power plants on the environment, the concentrations of the most important radionuclides were measured in soil samples from the local environments (0.4–5.2 km) as well as in fly ash. The spatial distribution of the radionuclides in the soil did not indicate any significantly increased concentrations in the area downwind of the plant compared to other areas; the ratios ²¹⁰Pb/²²⁶Ra and ²¹⁰Po/²²⁶Ra were within the range observed for unaffected soils. The emissions from the plant, though present, are obviously too small to significantly change the natural local distribution pattern of the radionuclides in the soil. A highly significant correlation between ⁴⁰K and ²³²Th was observed which was independent of the different types of soils found in this area. The concentration of ¹³⁷Cs in topsoil, which is the result of worldwide fallout from nuclear weapons testing, varied at some places even within a small distance (～ 2 km) by up to one order of magnitude. Furthermore, it was observed that the concentration of ¹³⁷Cs in soils from cropland was on average a factor of 2 less than in those from grassland. This variability has to be considered in planning monitoring programs around nuclear power plants, which may also release this radionuclide.     

Biogeochemical factors influencing net mercury methylation in contaminated freshwater sediments from the St. Lawrence River in Cornwall, Ontario, Canada

The activity of various anaerobic microbes, including sulfate reducers (SRB), iron reducers (FeRP) and methanogens (MPA) has been linked to mercury methylation in aquatic systems, although the relative importance of each microbial group in the overall process is poorly understood in natural sediments. The present study focused on the biogeochemical factors (i.e. the relative importance of various groups of anaerobic microbes (FeRP, SRB, and MPA) that affect net monomethylmercury (MMHg) formation in contaminated sediments of the St. Lawrence River (SRL) near Cornwall (Zone 1), Ontario, Canada. Methylation and demethylation potentials were measured separately by using isotope-enriched mercury species (²⁰⁰Hg²⁺ and MM¹⁹⁹Hg⁺) in sediment microcosms treated with specific microbial inhibitors. Sediments were sampled and incubated in the dark at room temperature in an anaerobic chamber for 96 h. The potential methylation rate constants (K_m) and demethylation rates (K_d) were found to differ significantly between microcosms. The MPA-inhibited microcosm had the highest potential methylation rate constant (0.016 d⁻¹), whereas the two SRB-inhibited microcosms had comparable potential methylation rate constants (0.003 d⁻¹ and 0.002 d⁻¹, respectively). The inhibition of methanogens stimulated net methylation by inhibiting demethylationand by stimulating methylation along with SRB activity. The inhibition of both methanogens and SRB was found to enhance the iron reduction rates but did not completely stop MMHg production. The strong positive correlation between K_m and Sulfate Reduction Rates (SRR) and between K_d and Methane Production Rates (MPR) supports the involvement of SRB in Hg methylation and MPA in MMHg demethylation in the sediments. In contrast, the strong negative correlation between K_d and Iron Reduction Rates (FeRR) shows that the increase in FeRR corresponds to a decrease in demethylation, indicating that iron reduction may influence net methylation in the SLR sediments by decreasing demethylation rather than favouring methylation.     

硅藻土/泥炭藓基负载g-C3N4-TiO2的光催化调湿性能

通过煅烧法制备具有异质结构的g?C3N4?TiO2光催化剂,然后与硅藻土/泥炭藓基调湿材料复合得到自然光驱动光催化调湿材料,并通过小室试验测试其降解甲醛和调湿的效果.采用X射线衍射仪(XRD)、环境扫描电子显微镜(ESEM)、紫外-可见分光光度计(UV?Vis)、傅里叶红外光谱仪(FTIR)和荧光光谱仪(PL)等研究了g?C3N4?TiO2/硅藻土/泥炭藓光催化调湿材料降解甲醛及温湿度调节的机制.结果表明:在尿素与TiO2质量比为5:1,520℃条件下煅烧制备的g?C3N4?TiO2光催化剂降解甲醛的效果最好,具有牢固的异质结,能有效减少光生电子和空穴的重组中心,使TiO2禁带宽变窄;由于光催化-吸附协同效应,NTD?5在自然光照下能够有效地将试验小室内的甲醛浓度和相对湿度分别控制在0.1 mg/m3和60％左右,同时还具有1～2℃的温度调节作用.     

Enhance the photocatalytic activity for the degradation of organic contaminants in water by incorporating TiO2 with zero-valent iron

Titanium dioxide (TiO₂) has become the most popular photocatalyst in treating persistent organic pollutants. The main disadvantage of TiO₂ is the diminishing photocatalytic activity over time due to the electron-hole pair recombination. Many studies have aimed to prolong the photocatalytic life of TiO₂. Among them, incorporation of zero-valent iron (ZVI) is one of the approaches. In this study, a novel nano TiO₂/Fe⁰ composite (NTFC) was synthesized from a nano neutral TiO₂ sol and a nano zero-valent iron (nZVI), both prepared in our laboratory. The structure, composition and physical property of the NTFC are characterized. The photocatalytic activity of the NTFC was evaluated by the reductive decolourization of an azo dye, Acid Black-24 (AB-24), and was found superior to those of nZVI and nano neutral TiO₂ sol. Evidence suggests that the enhanced activity of NTFC is highly correlated to the ratio of ferrous to ferric ion in the system. The quantities of ferrous and ferric ions in the nZVI and NTFC systems were monitored separately. In the nZVI system, the concentration of ferric ions decreased significantly with time while a high level of ferrous ions was maintained in the NTFC suspension. The ferrous/ferric ratio of the NTFC suspension was substantially increased after irradiation by UV. Evidence from EPR analysis suggests that the excited electrons in the conduction band of the TiO₂ can be trapped by the half reaction of Fe³⁺/Fe²⁺, reducing the probability of electron-electron hole pair recombination and sustaining the catalytic life of TiO₂. Corrosion tests further proved that by incorporating TiO₂ with zero-valent iron the surface oxidation of nZVI can be effectively prevented.     

HVAC air-quality model and its use to test a PM2.5 control strategy

This paper presents a MATLAB^® Simulink air-quality model of a commercial building with a heating, ventilation, and air conditioning (HVAC) system in Fairbanks, Alaska. Outdoor and indoor real-time fine particulate matter (PM_2.5) levels were measured at this building during a summer wild-fire smoke episode and then during a winter period. The correlation coefficient between the model-predicted and the measured indoor concentrations was 0.99 for the summer and 0.98 for the winter, justifying the usability of the model for further studies. An HVAC control algorithm was developed that reduces the indoor PM_2.5 levels. The algorithm was tested using the HVAC Simulink model and the outdoor PM_2.5 data from the summer smoke episode. The average indoor PM_2.5 level with this control algorithm was 65% lower than with the regular control. Thanks to the PM_2.5 control strategy being automatically engaged only during episodes, it was shown to have the potential of significantly reducing the indoor PM_2.5 levels without significantly compromising the purpose of the original control strategy.     

Traffic pollution affects tree-ring width and isotopic composition of Pinus pinea

This study presents new evidence that radiocarbon, combined with dendrochronological and stable isotopes analysis in tree rings and needles, can help to better understand the influence of pollution on trees. Pinus pinea individuals, adjacent to main roads in the urban area of Caserta (South Italy) and exposed to large amounts of traffic exhaust since 1980, were sampled and the time-related trend in the growth residuals was estimated. We found a consistent decrease in the ring width starting from 1980, with a slight increase in δ¹³C value, which was considered to be a consequence of environmental stress. No clear pattern was identified in δ¹⁵N, while an increasing effect of the fossil fuel dilution on the atmospheric bomb-enriched ¹⁴C background was detected in tree rings, possibly as a consequence of the increase in traffic exhausts. Our findings suggested that radiocarbon is a very sensitive tool to investigate small-scale (i.e. traffic exhaust at the level crossing) and large-scale (urban area pollution) induced disturbances.     

Greywater treatment by UVC/H2O2

Greywater treatment by UVC/H₂O₂ was investigated with regard to the removal of chemical oxygen demand (COD). A COD reduction from 225 to 30 mg l⁻¹ (overall removal of 87%) was achieved after settling overnight and subsequent irradiation for 3 h with 10 mM H₂O₂. Most of the contaminants were removed by oxidation since only 13% COD was removed by settlement.The removal of COD in the greywater followed a second-order kinetic equation, r = 0.0637[COD][H₂O₂], up to 10 mM H₂O₂. A slightly enhanced COD removal was observed at the initial pH of 10 compared with pH 3 and 7. This was attributed to the dissociation of H₂O₂ to O₂H⁻. The treatment was not affected by total concentration of carbonate (c_T) of at least 3 mM, above which operation between pH 3 and 5 was essential. The initial biodegradability of the settled greywater (as BOD₅:COD) was 0.22. After 2 h UVC/H₂O₂ treatment, a higher proportion of the residual contaminants was biodegradable (BOD₅:COD = 0.41) which indicated its potential as a pre-treatment for a biological process.     

Effect of COD/SO4ratio and Fe(II) under the variable hydraulic retention time (HRT) on fermentative hydrogen production

The effect of chemical oxygen demand/sulfate (COD/SO₄²⁻) ratio on fermentative hydrogen production using enriched mixed microflora has been studied. The chemostat system maintained with a substrate (glucose) concentration of 15 g COD L⁻¹ exhibited stable H₂ production at inlet sulfate concentrations of 0-20 g L⁻¹ during 282 days. The tested COD/SO₄²⁻ ratios ranged from 150 to 0.75 (with control) at pH 5.5 with hydraulic retention time (HRT) of 24, 12 and 6 h. The hydrogen production at HRT 6 h and pH 5.5 was not influenced by decreasing the COD/SO₄²⁻ ratio from 150 to 15 (with control) followed by noticeable increase at COD/SO₄²⁻ ratios of 5 and 3, but it was slightly decreased when the COD/SO₄²⁻ ratio further decreased to 1.5 and 0.75. These results indicate that high sulfate concentrations (up to 20,000 mg L⁻¹) would not interfere with hydrogen production under the investigated experimental conditions. Maximum hydrogen production was 2.95, 4.60 and 9.40 L day⁻¹ with hydrogen yields of 2.0, 1.8 and 1.6 mol H₂ mol⁻¹ glucose at HRTs of 24, 12 and 6 h, respectively. The volatile fatty acid (VFA) fraction produced during the reaction was in the order of butyrate > acetate > ethanol > propionate in all experiments. Fluorescence In Situ Hybridization (FISH) analysis indicated the presence of Clostridium spp., Clostridium butyricum, Clostridium perfringens and Ruminococcus flavefaciens as hydrogen producing bacteria (HPB) and absence of sulfate reducing bacteria (SRB) in our study.