金-银建造和金-锑建造矿床形成的物理-化学条件

<正> 金-锑建造和金-银建造矿床广泛发育于世界上许多矿区。但是在所有地方,这两种建造的矿床在空间上都是分离的。在太平洋成矿带中,金-银矿床位于外带;而金-锑矿床位于内带。在两个带相接地段有时形成过渡的金-锑-银建造的矿床。具有数量比值不同的金和锑是上述矿床中的共同点。至于银,它对金-锑建造     

天然金-银系列化合物中的汞及其在升华温度范围内可能存在的形式

详细研究了不同矿石建造矿床的天然金-银系列化合物中汞的分布。对于金-碲化物建造矿床和金-辉锑矿建造矿床中的金来说,其特点是汞含量偏高。天然Au-Ag-Hg体系的固溶体分布很少,在它们当中以金为主体的固溶体占多数。金-银系列化合物中承的热浓集谱,(?)可作为不同金矿建造和矿物类型的矿床的可靠的特征标志。     

金-银建造的矿床类型

<正> 近年来,所获得的关于金-银矿床形成条件的资料,表明了必须准确地说明“金-银建造”概念,以及建造划分准则和矿床分类。多年来,一直认为金-银建造只与年轻的火山岩带有联系(В.Линдгрен,Γ。Шнейдерхен等)。近期通过对研究鄂霍茨克-楚克奇火山岩带中生代矿床和天山古生代矿床的研究,扩大了金-银建造的时代范围,同时对作为最典型的火山岩系列成矿建造之一的金-银建造的认识没有改变。     

营养盐添加对水华蓝藻——卵孢金孢藻生长和竞争影响的原位实验

为探究在水体营养盐浓度持续增加的条件下,卵孢金孢藻(Chrysosporum ovalisporum)的生长趋势和其它藻类的生长响应,在上海滴水湖畔采用39个大桶(100 L)进行不同浓度N、P添加的原位中型模拟实验.结果表明,高浓度营养盐添加可促进卵孢金孢藻和绿藻生物量的增加,加P组二者生物量的增加趋势高于加N组,但差异并不显著(P0.05),加NP组二者生物量的增加趋势显著高于加N组和加P组(P0.001).在加N组和加NP组,卵孢金孢藻相对丰度随营养盐添加量的增加呈显著的下降趋势(P0.05),而在加P组其相对丰度随着P浓度的增加略有上升,但不显著(P0.05).实验结束时,所有处理组中卵孢金孢藻的生物量不占优势,而小粒径藻类[色球藻属(Chroococcus spp.)、空星藻属(Coelastrum spp.)、小球藻属(Chlorella spp.)、四角藻属(Tetraedron spp.)、栅藻属(Scenedesmus spp.)]的生物量随营养盐浓度升高的增加趋势显著高于卵孢金孢藻(P0.05),小型绿藻占据绝对优势,表明在高温和相对静止的条件下,随着水体中营养盐浓度的持续增加,小粒径藻类易替代卵孢金孢藻而占据竞争优势;这与小粒径藻类在高营养条件下代谢速率较高有关,也与绿藻喜静止、高光强的生物学特性有关.小型绿藻占据优势可能成为小型超富营养水体中浮游植物群落在高温季节的演替方向之一.     

锡与金的关系

<正> 近几十年来发现了一系列综合性的金-锡矿床、金-锡-钨矿床。在苏联东北部,锡矿带和金矿带在空间上的掩覆是有规律的。在锡石-硫化物建造的矿石中经常有银存在,这就使我们可以提出关于这种锡-银矿床具有独立建造以及这种矿床在空间上与金-银建造矿床相共生的观点。     

金矿床的同位素地球化学模式

在金-硫化物建造(Ⅰ)和石英-金-硫化物建造(Ⅱ)矿床的典型剖面中,根据硫化矿物沉淀时的物理-化学条件以及硫化矿物集合体的成分,将单元矿带表现出的同位素地球化学分带划分出四个同位素地球化学组合,建立了这两种建造金矿床的同位素地球化学模式。该模式可用于评价矿床深部层位和矿田异常地段的金矿化远景,解释矿化带的内部结构及确定矿化带的侵蚀面水平。     

不同水生植物组合修复城市水体研究

目前城市水体仍面临不同程度的污染问题,以水生植物为主的生态修复是应用较为广泛的技术方法。水生植物修复水体应用过程中存在种植搭配技术方法不科学、修复效果不理想、应用条件不明确等问题。该研究考察在植物物种丰度不同条件下（水生植物植株数量相同、生物量接近,物种丰度不同）,水生植物对水体污染物（总氮、总磷、化学需氧量）削减和对水体溶解氧含量影响的差异。试验设置了2组不同水生植物物种丰度的搭配组合实验组,低丰度实验组为苦草+芦苇,高丰度实验组为金鱼藻+狐尾藻+芦苇+鸢尾。试验进水水质为地表水劣Ⅴ类水质,出水水质稳定保持在地表水Ⅰ类水水质标准,其中高丰度组对化学需氧量的去除效率比低丰度组对化学需氧量的去除效率高14.3%;高丰度组和低丰度组表面底泥TOC含量较初始底泥分别减少了12.3%和7.4%,高丰度组和低丰度组底层底泥TOC含量较初始底泥分别减少了32.8%和30.4%。观察叶片表面发现高丰度组沉水植物叶片表面微生物丰度明显高于低丰度组。通过该研究发现水生植物物种丰度提升有助于增强水体污染物削减效果,提升水体生物多样性,稳定水体生态。     

论元素丰度与环境友好型生产工艺

通过对地壳、海洋及人体中16种元素丰度的分析,得出了环境友好型生产工艺的3个特征,即：整体偏碱性、氧硫比接近2000：1、避免使用低丰度元素。此外还结合上述特征对加压氧化-氰化法和次氯酸钠一步浸金工艺的环境友好性进行了分析。     

金的气相迁移探索

金能生成单原子蒸气金，也能生成气溶胶金，近年又有人认为存在金的气态分子Au2。由于纳米物质的熔点和沸点温度低，在地球内部的温度条件下，丰度值极小的金、稀有元素、贵金属及某些化合物将会气化或生成气溶胶，以地球排气作用的方式迁移到地壳的表层或大气中。     

煤中发现镉矿物

镉对环境和人体健康有巨大的危害 ,但煤中镉的含量一般远低于它在地壳中的丰度 ,所以人们对于煤中镉的关注程度较低。笔者在研究黔西南高砷煤的过程中 ,发现有镉矿物 ,这对于认识镉在成煤过程中的行为和燃煤可能造成的镉污染具有积极的意义。黔西南处于滇 黔 桂微细浸染型金矿区 ,而且同时也处于贵州碳酸盐建造中的Ｈｇ Ｓｂ Ａｓ Ｔｌ成矿带上[1 ] ,中低温成矿元素 (Ｈｇ、Ｓｂ、Ａｓ、Ｔｌ)和卤族元素富集[2 ] 。含有镉矿物的高砷煤产于贵州省黔西南苗族布依族自治州兴仁县 ,为上二叠统龙潭组的无烟煤 ,在该区高砷煤中 ,其砷含量较低 ,但…     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effect of sorbed and desorbed Zn(Ⅱ) on the growth of a green alga (Chlorella pyrenoidosa)

Toxic effect of Zn(Ⅱ) on a green alga (Chlorella pyrenoidasa) in the presence of sepiolite and kaolinite was investigated.The Zn-free clays were found to have a negative impact on the growth of C.pyrenoidosa in comparison with control samples (without adding any clay or Zn(Ⅱ)).When Zn(Ⅱ) was added,the algae in the presence of clays could be better survived than the control samples,which was actually caused by a decrease in Zn(Ⅱ) concentration in the solution owing to the adsorption of Zn(Ⅱ) on the clays.When the solution system was diluted,the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn(Ⅱ) concentration as in the diluted system.This in fact resulted from desorption of Zn(Ⅱ) from the zinc-contaminated clays,although the effect varied according to the different desorption capabilities of sepiolite and kaolinite.Therefore the adsorption and desorption processes of Zn(Ⅱ) played an important part in its toxicity,and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.