Impact of depositional and biogeochemical processes on small scale variations in nodule abundance in the Clarion‐Clipperton Fracture Zone

Manganese nodules of the Clarion–Clipperton Fracture Zone (CCFZ) in the NE Pacific Ocean are highly enriched in Ni, Cu, Co, Mo and rare-earth elements, and thus may be the subject of future mining operations. Elucidating the depositional and biogeochemical processes that contribute to nodule formation, as well as the respective redox environment, in both water column and sediment, supports our ability to locate future nodule deposits and to evaluate the potential ecological and environmental effects of future deep-sea mining. For these purposes we studied the local hydrodynamics and pore-water geochemistry with respect to the nodule coverage at four sites in the eastern CCFZ. Furthermore, we carried out selective leaching experiments at these sites in order to assess the potential mobility of Mn in the solid phase, and compared them with the spatial variations in sedimentation rates. We found that the oxygen penetration depth is 180–300 cm at all four sites, while reduction of Mn and NO₃⁻ is only significant below the oxygen penetration depth at sites with small or no nodules on the sediment surface. At the site without nodules, potential microbial respiration rates, determined by incubation experiments using ¹⁴C-labeled acetate, are slightly higher than at sites with nodules. Leaching experiments showed that surface sediments covered with big or medium-sized nodules are enriched in mobilizable Mn. Our deep oxygen measurements and pore-water data suggest that hydrogenetic and oxic-diagenetic processes control the present-day nodule growth at these sites, since free manganese from deeper sediments is unable to reach the sediment surface. We propose that the observed strong lateral contrasts in nodule size and abundance are sensitive to sedimentation rates, which in turn, are controlled by small-scale variations in seafloor topography and bottom-water current intensity.     

对重金属和辐射污染的土壤和地下水的微生物修复

由重金属和辐射产生的环境污染在世界范围内产生了一系列问题.利用特殊的微生物如金属还原和耐金属细菌对环境中的金属和辐射污染进行处理具有非常好的前景.现场的生物修复的成功应用将对清除污染环境中的重金属和辐射提供潜在方法.最近的研究还关注于了解在微生物群体内重金属和辐射对微生物的作用.生物毯和生物膜是在生物修复中具有代表性的两种微生物群落的机能.金属的种类和价态变化、转移过程以及微生物代谢作用是对金属和辐射生物修复的三种重要的组成部分.结合以上三方面,可以更好的了解自然中的微生物和生物修复过程之间的关系.     

论贵东岩体东西部花岗岩岩石学特征和铀成矿条件差异性

通过对贵东岩体花岗岩岩石学特征和铀地球化学性状的系统研究,认为贵东岩体主体花岗岩是由有一定时间间隔的三期花岗岩在空间上的复合,即东部的下庄岩体、东南部的鲁溪岩体和西部的隘子岩体,三期花岗岩为不同源区地壳物质部分熔融的产物。东部下庄岩体的富铀性和铀的强烈活化,使它成为该区唯一有利的成矿铀源体,阐明了贵东岩体东部成矿西部不成矿的根本原因,指出今后的找矿重点还应放在东部地区。     

甘肃省西成铅锌矿田矿源层的确定及其Pb—Zn活化机理研究

本文以地层地球化学、同位素地球化学等理论为指导,论证了西成铅锌矿田成矿金属物质主要来自基底前泥盆系;在查明矿田成矿物理化学条件和基底地层铅锌赋存形式的基础上,以成矿模拟实验为手段,探讨了基底地层中成矿元素Pb、Zn的活化机理及其控制因素。     

PARAMETERIZATION OF MOBILIZATION AND TRANSPORT OF SAND-DUST DURING BLACK STORM AND MESOSCALE NUMERICAL EXPERIMENTS*

The typical black storms or sand-dust storms in the northwestern China are generated and developed through an interaction between the specific large scale circulation pattern and mesoseale systems.The passing by/over a huge sand-abundant desert of a strong cold front with intensive frontal zone at mid and lower levels is a necessary condition for the formation and development of a black storm or a severe sand-dust storm.In order to investigate the mechanism of the sand-dustmobilization,transport and sedimentation during the black or sand-dust storms,a parameterization scheme of sand-dust source-sink terms and an equation of transport for the sand-dust were proposed and incorporated into the MM4 mesoscale model.The modified MM4 model was applied to the "May 1993" black storm case and succeeded in reproducing the evolution of the weather systems associated with the black-storm,the sand-dust concentration at surface layer and its vertical distribution,and the sand-dust sedimentation and transport.Our results show that the numerical simulating method by using a mesoscale model,with inclusion of an equation of the sand-dust transport and a parameterization scheme of the sand-dust source-sink terms,is a promising approach to study the mechanism for sand-dust mobilization,transport and sedimentation during a sand-dust storm event.     

Pb and Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

Vertical profiles of dissolved and particulate ²¹⁰Po and ²¹⁰Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O₂/H₂S interface facilitates the aerobic dissolution of MnO₂. In contrast, Fe(II) concentrations begin to increase only at the O₂/H₂S interface depth. Activity profiles reveal that dissolved ²¹⁰Po and ²¹⁰Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both ²¹⁰Po and ²¹⁰Pb are highly enriched at the O₂/H₂S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in ²¹⁰Po, ²¹⁰Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated.     

南极拉斯曼丘陵高级区假蓝宝石及有关矿物组合的形成过程

通过对南极拉斯曼丘陵含假蓝宝石矿物及有关组合的研究,得知假蓝宝石的成分以富镁、铁、铝但贫硅为特征,其粒间及粒内成分的变化均较为明显,这种变化主要表现为以钙契尔马克代换(Mg, Fe) + Si = 2Al为主的类质同象置换。在形成假蓝宝石的高级变质-深熔作用过程中,岩石矿物组合的变化主要是多阶段变质造成的,如浅-暗色组分发生了分离,其中含镁铁组分多的矿物较早结晶,而镁铁组分的分离使得相对富Fe的矿物较早结晶,即晚期形成的镁铁质矿物更富Mg组分,并形成递进演化的不同阶段的组合。假蓝宝石的出现与组分的活动有关,而不仅仅是由岩石成分决定的。变质矿物组合的多次递进演化,反映了活动组分的不断变化,以及体系组分相当程度的开放性。含假蓝宝石的变质岩石之原岩未必是富镁泥质岩。本区假蓝宝石成分的多变性主要是环境成分而不是pT变化所引起的,假蓝宝石形成于840~880℃,并没有达到超高温（>1 000℃）的条件,其形成与高级变质-深熔作用过程中组分渗透和扩散的共同作用有关。     

半宽金矿床的物质来源及成因讨论

半宽金矿床的成矿物质具有多源性.微量元素特征显示金矿床的成矿物质来自混合岩.同位素研究表明含矿流体为岩浆成因,但有变质流体和天水的混合.稀土元素特征反映矿质来自下地壳或地幔,是下地壳物质重熔的结果,但受到上壳岩石的混染.矿床的成因为岩浆活化的金矿床.     

烧房沟滑坡型泥石流工程治理及效果分析

国内对泥石流治理措施谷坊坝、格栅坝的作用和效果研究较多,而对滑坡型泥石流的综合治理措施和效果研究较少。2010.8.14强降雨过程导致汶川震区映秀镇烧房沟滑坡型泥石流暴发,通过分析其运动过程和现状沟道特征,结合滑坡堵点和沟道深切的特点,治理工程采用防堵防切综合工程结构形式:上游谷防群+中游抗滑桩、挡土板和肋板护脚护底+下游3座格栅坝+渡槽明洞跨越G213,并分析各分项工程作用:减弱龙头动能+控制LS01堵点、保护鞋尖+拦粗放细、顺畅排导。最后利用2010.8.14与2013.7.10的历史降雨量和固体参与量对比、工程治理前后动储量对比和各分项工程治理前后的沟道特点对比,验证了烧房沟滑坡型泥石流综合治理工程的效果良好。为今后震区滑坡型泥石流工程防治提供参考。     

Geochemical and mineralogical control on the mobility of arsenic in a waste rock pile at Dlouhá Ves,Czech Republic

A waste rock pile with initial high sulfide (10–20 wt.%) and low carbonate content (1–2 wt.%) located at Dlouhá Ves in the Czech Republic has been investigated in two profiles (excavation and outcrop) using powder X-ray diffraction, electron microprobe analysis, bulk composition analysis and Mössbauer spectroscopy. The mobility of arsenic and other contaminants was evaluated by leaching experiments. The primary source of the arsenic was arsenopyrite, which was significantly oxidized in both profiles. The principal As-bearing phase at the excavation profile was goethite, located at the top of the profile, and minerals of the jarosite group which were found down to its base. Melanterite, rich in copper and zinc, was found in a sulfide-rich, lower part of the profile together with anglesite. At the outcrop profile, minerals of the jarosite–beudantite group, scorodite and kaňkite prevail and no Fe(II)-minerals were found. The paste pH was lower at the excavation profile (minimum about 1.9) than at the outcrop profile (minimum of about 2.8). Processes in the pile are affected by the pyrite/arsenopyrite ratio, where high pyrite content decreases the As/S ratio and results in the formation of jarosite group minerals and low pH conditions. Where arsenopyrite predominates, sulphides are coated by scorodite and other Fe–As phases like schwertmannite, which limit their further oxidation.