宁乡式铁矿成因新解——后生热液成因的地质与地球化学证据

宁乡式铁矿床广泛分布于华南及四川盆地等地区,矿体呈层状产于浅海相细碎屑岩—碳酸盐岩中,局部形态复杂,常见穿切关系及以鲕状赤铁矿为胶结物的角砾状矿石,围岩蚀变弱.矿床及矿石未遭受明显的后期热变质影响.矿石矿物为鲕状赤铁矿,大部分矿床中还共生有磁铁矿、菱铁矿,少量黄铁矿,脉石矿物主要是白云石、方解石.石英砂粒表面遭受溶蚀而不平.矿石中常见完整的化石与鲕粒共存,部分化石被镜铁矿、磁铁矿交代,细粒白云石作为胶结物.矿石碳酸盐的δ13C为-2.8‰～-4‰,δ18O为18.7‰～ 20.7‰,87Sr/86 Sr为0.7132 ～ 0.7176,不同于正常沉积的海相碳酸盐岩,而与密西西比河谷型(MVT)铅锌矿床相似,且自近矿围岩→赤铁矿矿石→磁铁矿矿石→菱铁矿矿石,δ13C、δ18O降低,86Sr/87 Sr升高.地质地球化学特征均显示,宁乡式铁矿可能并非简单的浅海相正常沉积矿床,而更可能是后生的,成矿作用可能与盆地卤水作用有关,沿特定层位交代成矿.     

Copper desorption from Gelidium algal biomass

Desorption of divalent copper from marine algae Gelidium sesquipedale, an algal waste (from agar extraction industry) and a composite material (the algal waste immobilized in polyacrylonitrile) was studied in a batch system. Copper ions were first adsorbed until saturation and then desorbed by HNO(3) and Na(2)EDTA solutions. Elution efficiency using HNO(3) increases as pH decreases. At pH=1, for a solid to liquid ratio S/L=4gl(-1), elution efficiency was 97%, 95% and 88%, the stoichiometric coefficient for the ionic exchange, 0.70+/-0.02, 0.73+/-0.05 and 0.76+/-0.06 and the selectivity coefficient, 0.93+/-0.07, 1.0+/-0.3 and 1.1+/-0.3, respectively, for algae Gelidium, algal waste and composite material. Complexation of copper ions by EDTA occurs in a molar proportion of 1:1 and the elution efficiency increases with EDTA concentration. For concentrations of 1.4, 0.88 and 0.57 mmoll(-1), the elution efficiency for S/L=4gl(-1), was 91%, 86% and 78%, respectively, for algae Gelidium, algal waste and composite material. The S/L ratio, in the range 1-20gl(-1), has little influence on copper recovery by using 0.1M HNO(3). Desorption kinetics was very fast for all biosorbents. Kinetic data using HNO(3) as eluant were well described by the mass transfer model, considering the average metal concentration in the solid phase and the equilibrium relationship given by the mass action law. The homogeneous diffusion coefficient varied between 1.0 x 10(-7)cm(2)s(-1) for algae Gelidium and 3.0 x 10(-7)cm(2)s(-1) for the composite material.     

Laboratory tests of ammonium and barley straw extract as agents to suppress abundance of the harmful alga Prymnesium parvum and its toxicity to fish

Prymnesium parvum is a harmful alga whose blooms can cause fish kills in brackish waters. Two potential suppressants of this alga were tested, ammonium and barley straw extract (BSE), at temperatures of 10, 20 and 30 degrees C. Laboratory batch cultures were grown for 3 weeks at each temperature, with weekly doses of ammonium or BSE at either low or high levels, or a no-dose control treatment. The growth rate of P. parvum during exponential phase was highest at 20 degrees C and lowest at 10 degrees C, and was stimulated by the highest ammonium dose. Only cultures grown at 20 degrees C were toxic to fish. The highest ammonium dose abolished such toxicity and reduced the endpoint population density of P. parvum. BSE did not reduce the exponential growth rate, endpoint density, or toxicity to fish of P. parvum. The results support the use of ammonium additions, but not BSE, to suppress harmful blooms of P. parvum in those circumstances where the possible disadvantages can be managed.     

某鲕状赤褐铁矿流化床磁化焙烧-磁选工艺

采用流化床反应器作为磁化焙烧装置,以高纯N2和CO混合气体作为还原气体,考察了550~800℃下,云南某地区的鲕状赤褐铁矿磁化焙烧-磁选的影响因素. 结果表明,未经过预处理的矿粉采用磁化焙烧-磁选分离,精矿中铁品位可提高至约55%,铁回收率<70%;经过预处理的矿粉,精矿中铁品位可提高至60.18%,铁回收率达85.91%. 预处理矿粉形成了多孔疏松结构,使还原气体易进入铁矿颗粒内部,有利于Fe3O4生成,提高了磁选指标.     

Palatability of Macroalgae that Use Different Types of Chemical Defenses

This study compared algal palatability and chemical defenses from subtropical green algae that may use different types of defense systems that deter feeding by the rock-boring sea urchin Echinometra lucunter. The potential defense systems present include (1) the terpenoid caulerpenyne and its activated products from Caulerpa spp., and (2) dimethylsulfoniopropionate (DMSP)-related defenses in Ulva spp. Secondary metabolites from these chemical groups have been shown to deter feeding by various marine herbivores, including tropical and temperate sea urchins. Live algal multiple-choice feeding assays and assays incorporating algal extracts or isolated metabolites into an artificial diet were conducted. Several green algae, including Ulva lactuca, Caulerpa prolifera, and Cladophora sp., were unpalatable. Nonpolar extracts from U. lactuca deterred feeding, whereas nonpolar extracts from C. prolifera had no effect on feeding. Polar extracts from both species stimulated feeding. Caulerpenyne deterred feeding at approximately 4% dry mass; however, dimethyl sulfide and acrylic acid had no effect at natural and elevated concentrations. E. lucunter is more tolerant than other sea urchins to DMSP-related defenses and less tolerant to caulerpenyne than many reef fish. Understanding the chemical defenses of the algae tested in this study is important because they, and related species, frequently are invasive or form blooms, and can significantly modify marine ecosystems.     

Hydrogen production from Chlamydomonas reinhardtii biomass using a two-step conversion process: Anaerobic conversion and photosynthetic fermentation

Chlamydomonas reinhardtii UTEX 90 accumulated 1.45 g dry cell weight and 0.77 g starch/L during photosynthetic growth using TAP media at 25 ^°C${}^{°}\mathrm{C}$ in presence of 2% _CO2${\mathrm{CO}}_2$ for 3 days. C. reinhardtii biomass was concentrated and then converted into hydrogen and organic acids by anaerobic fermentation with Clostridium butyricum. Organic acids in the fermentate of algal biomass were consecutively photo-dissimilated to hydrogen by Rhodobacter sphaeroides KD131. In the concentrated algal biomass 52% of the starch was hydrolyzed to 37.1 mmol _H2${\mathrm{H}}_2$/L-concentrated algal biomass and 13.6, 25.5, 7.4 and 493 mM of formate, acetate, propionate, and butyrate, respectively by C. butyricum. R. sphaeroides KD131 evolved 5.72 mmol _H2${\mathrm{H}}_2$ per ml-fermentate of algal biomass under illumination of 8 klux at 30 ^°C${}^{°}\mathrm{C}$. Only 80% of the organic acids, mainly butyrate, were hydrolyzed during photo-incubation. During anaerobic conversion, 2.58 mol _H2/mol${\mathrm{H}}_2/\mathrm{mol}$ starch–glucose was evolved using C. butyricum and then 5.72 mol _H2/L${\mathrm{H}}_2/\mathrm{L}$-anaerobic fermentate was produced by R. sphaeroides KD131. Thus, the two-step conversion process produced 8.30 mol _H2${\mathrm{H}}_2$ from 1 mol starch–glucose equivalent algal biomass via organic acids.     

川东飞仙关组鲕滩储层地震响应特征及预测

川东下三叠统飞仙关组鲕滩气藏是川东地区的重要气藏类型之一，“亮点”型反射特征识别鲕滩储层在研究区内成功率较高，但失败的钻井也不少。为了更有效地进行鲕滩储层的预测，结合区内多口成功和失败钻井，从测井、地震反射特征、地震层序等方面进行了分析，指出“亮点”型反射具有多解性和不确定性。通过对钻遇的含气鲕粒岩储层成岩环境的分析，得到了2点认识：①鲕滩白云岩化是其成为有效储层的必要条件；②鲕滩沉积时近于暴露的古地理环境为其白云岩化提供了条件。此外，还利用地震地层学和层序地层学来识别古沉积环境，以排除无效“亮点”。     

Recovery of metallic iron from high phosphorus oolitic hematite by carbothermic reduction and magnetic separation

Abstract

This study aims to provide theoretical and technical basis for economical and rational use of high phosphorus oolitic hematite. Following physical, chemical and microscopic characterisation of high phosphorus oolitic hematite ore the feasibility of separation of phosphorus and metallic iron by reduction roasting and magnetic separation process were investigated. The results indicate that such a process is a feasible and efficient method for iron and phosphorus separation of high phosphorus oolitic hematite. The recovery of metallic iron and dephosphorisation rate is relatively low without additives but is significantly improved by appropriate CaO and Na₂CO₃ addition. With 8%CaO and 3%Na₂CO₃ the recovery of metallic iron and dephosphorisation rate reach 95.1 and 94.0% respectively.     

藻鲕变形及定向性的研究

多数人在研究碳酸盐沉积物(岩)的压实作用时往往注重重荷压实作用,对于侧向挤压的压实作用,则注意不够。本文通过对广西田林县浪平甘硐子中上泥盆统藻鲕颗粒灰岩中藻鲕变形及定向性的研究,确认藻鲕的变形及定向并非重荷压实作用的结果,而是三叠纪中期以前的印支—燕山运动的产物。控制藻鲕变形及定向的因素是构造压实作用、早期胶结作用、颗粒成分、重荷压实作用及溶蚀—充填作用等,其中构造压实作用、早期胶结作用及颗粒成分是主要的因素。     

A novel ocean color index to detect floating algae in the global oceans

Various types of floating algae have been reported in open oceans and coastal waters, yet accurate and timely detection of these relatively small surface features using traditional satellite data and algorithms has been difficult or even impossible due to lack of spatial resolution, coverage, revisit frequency, or due to inherent algorithm limitations. Here, a simple ocean color index, namely the Floating Algae Index (FAI), is developed and used to detect floating algae in open ocean environments using the medium-resolution (250- and 500-m) data from operational MODIS (Moderate Resolution Imaging Spectroradiometer) instruments. FAI is defined as the difference between reflectance at 859 nm (vegetation “red edge”) and a linear baseline between the red band (645 nm) and short-wave infrared band (1240 or 1640 nm). Through data comparison and model simulations, FAI has shown advantages over the traditional NDVI (Normalized Difference Vegetation Index) or EVI (Enhanced Vegetation Index) because FAI is less sensitive to changes in environmental and observing conditions (aerosol type and thickness, solar/viewing geometry, and sun glint) and can “see” through thin clouds. The baseline subtraction method provides a simple yet effective means for atmospheric correction, through which floating algae can be easily recognized and delineated in various ocean waters, including the North Atlantic Ocean, Gulf of Mexico, Yellow Sea, and East China Sea. Because similar spectral bands are available on many existing and planned satellite sensors such as Landsat TM/ETM+ and VIIRS (Visible Infrared Imager/Radiometer Suite), the FAI concept is extendable to establish a long-term record of these ecologically important ocean plants.