Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings,China

To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria(PGPB). It shows that: Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF(Cation Diffusion Facilitator), Hup E/Ure J and CHR(chromate ion transporter) family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid(IAA) secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.     

Sulfide elimination by intermittent nitrate dosing in sewer sediments

The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards, and requires expensive programs for its prevention. The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments. The study was carried out based on lab-scale experiments and batch tests using real sewer sediments. The intermittent nitrate dosing mode and the optimal control condition were investigated. The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment. The oxidation–reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S(nitrate/sulfide)ratio with slight excess nitrate is necessary for optimal conditions of efficient sulfide control with lower carbon source loss. The optimal control condition is feasible for the sulfide elimination in sewer systems.     

Comparison of three-dimensional fluorescence analysis methods for predicting formation of trihalomethanes and haloacetic acids

This work investigated the application of several fluorescence excitation–emission matrix analysis methods as natural organic matter(NOM) indicators for use in predicting the formation of trihalomethanes(THMs) and haloacetic acids(HAAs). Waters from four different sources(two rivers and two lakes) were subjected to jar testing followed by 24 hr disinfection by-product formation tests using chlorine. NOM was quantified using three common measures: dissolved organic carbon, ultraviolet absorbance at 254 nm, and specific ultraviolet absorbance as well as by principal component analysis, peak picking,and parallel factor analysis of fluorescence spectra. Based on multi-linear modeling of THMs and HAAs, principle component(PC) scores resulted in the lowest mean squared prediction error of cross-folded test sets(THMs: 43.7(μg/L)2, HAAs: 233.3(μg/L)2). Inclusion of principle components representative of protein-like material significantly decreased prediction error for both THMs and HAAs. Parallel factor analysis did not identify a protein-like component and resulted in prediction errors similar to traditional NOM surrogates as well as fluorescence peak picking. These results support the value of fluorescence excitation–emission matrix–principal component analysis as a suitable NOM indicator in predicting the formation of THMs and HAAs for the water sources studied.     

Surface modification of polypropylene non-woven fibers with TiO2 nanoparticles via layer-by-layer self assembly method: Preparation and photocatalytic activity

Polypropylene (PP) meltblown fibers were coated with titanium dioxide (TiO₂) nanoparticles using layer-by-layer (LbL) deposition technique. The fibers were first modified with 3 layers of poly(4-styrenesulfonic acid) (PSS) and poly(diallyl-dimethylammonium chloride) (PDADMAC) to improve the anchoring of the TiO₂ nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic TiO₂ nanoparticles to construct TiO₂/PDADMAC bilayer in the LbL fashion. The number of deposited TiO₂/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust TiO₂ loading. The LbL technique showed higher TiO₂ loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue (MB). Results showed that the TiO₂ modified fibers exhibited excellent photocatalytic activity efficiency similar to that of TiO₂ powder dispersed in solution. The deposition of TiO₂ 3 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr. TiO₂-LbL constructions also preserved TiO₂ adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of TiO₂ particles from the substrate outer surface. However, even in the third cycle, the TiO₂ modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.     

Fuelwood assessment at the micro-watershed level:a case study in Garhwal Himalaya,India

Biomass,as fuelwood,is one of the major sources of energy in rural areas,especially in the mountainous regions of the world.As the increasing human population exerts more pressure on the forest thereby inducing an adverse effect on the sustainability of the ecosystem,which consequently causes fuelwood crisis at a local level,this crisis is spatio-temporal in nature.Thus,the major objective of this study is to assess the sustainability of fuelwood at different probable scenarios at a micro watershed level.The present study was conducted in the Phakot watershed,the Tehri Garhwal district of central Himalaya in India,during 2006-2008.Based on the vegetation composition in the study area,the net primary productivity(NPP)value of the Oak forest,and mixed oak and sal forests,was used for the quantification of fuelwood availability in evergreen and deciduous forests,respectively.The fuelwood demand was calculated on the basis of seasonal fuelwood consumption values.Nine probable permutations for availability-demand scenarios assuming the existence of high(H),low(L)and average(A)conditions were analyzed for evaluating the stress.The available annual harvestable fuelwood in the watershed is in the minimum and maximum ranges of 2283.28 to 4066.00 tons,respectively,per year whereas it has a demand of 110.76 tons as the minimum to 3659 tons as the maximum annually.This shows that in the current availabilitydemand scenario,the watershed does not have fuelwood crisis in the present situation but needs to maintain the sustainability of the system.Based on our study,it is concluded that,globally,more spatio-temporal study is required to understand the issues at the local level.     

安大略西北西尔里Cu-Ni矿床的地质学

<正> 本文的目的是讨论西尔里矿床的岩石学、构造地质学和岩石的化学蚀变及其与Cu-Ni矿化的关系。西尔里矿床位于安大略桑德贝西北450km。钻探已圈出一千四百万吨矿石,含铜1.60％。西尔里矿床产于镁铁-超镁铁岩及其剪切带中。     

地面地球化学测量在烃类普查中的综合运用(以列文楚夫凝析气田为例)

根据因子分析,划分出两个基本的成油过程:土壤溶液的氧化还原条件在后生烃影响下向着还原碱性环境的方向转移;由烃氧化微生物群的生命活动引起的次生碳酸盐化作用。地球化学工作的效率和测量工作的合理组合决定于区域的景观-地球化学条件。     

1979—1982年成矿作用研究的进展

<正> 过去的四年中,在成矿作用方面取得了两个主要进展:海底“黑烟囱”(smoker)的发现和矿床模式概念的形成。第一个进展的取得是意想不到的。1978年,由法国、墨西哥和美国科学家联合组成的海洋考察队,在下加利福尼亚南面北纬21°海域勘探东太平洋隆起时发现了不活动的深海热液喷口,在其周围有Zn、Cu和Fe的硫化物沉积物,不久又首次发现了     

闪锌矿中记录的矿体冷却史——日本津茂夕卡岩矿床的一个实例

<正> 引言 众所周知,闪锌矿中常含有磁黄铁矿和(或)黄铜矿的叶片和细点。自Schwartz(1931)等的经典著作发表以来,这些结构一直被解释为出溶产物。本文对含有许多磁黄铁矿和黄铜矿不规则颗粒、叶片和细点的闪锌矿样品进行了详细的电子探针分析和辅助的加热实验研究。这些研究,根据Cu-Fe-Zn-S体系的近代知识,可以对样品中所观测到的结构进行成功的解释。     

Analysis and Modeling on the Spatial Structure of Urban Land Use: A Case of Jinan, China

Based on the data of urban land use obtained by remote sensing interpretation from aero images in 1986 and 2004, the spatial structure of Jinan is studied in this paper with the method of Geographic Information System (GIS). According to the proportion of land for residence, industry and commerce, the urban district can be distinguished into three rings. Compared with the traditional theory of the ring structure in Western coun- tries, they have many distinctive characteristics. The main func- tions of the inner ring include residence, business and banking, but the proportion of residential land (more than 50%) is considerably higher than that of the cities in Western countries. The land proportion for residence and industry in the intermediate ring is equal on the whole. The main land of the outside ring is for industrial use. From 1986 to 2004, great changes have taken place on the land proportion of different types of use. In the inner ring, the land for residential and industrial use has shrunk much while the land for commercial use has increased. In the intermediate ring, the changes of the three types of land use were not very much and the temporal variation was relatively stable. On the contrary, the structure in the outside ring varies acutely. Though most of it is also for industrial use, the proportion of residential land has in- creased much. The three rings can also be divided into several sectors respectively, according to the function of land use clusters. New trends and mechanisms of the changes of land use impacting the urban structure were proposed in the end of the paper.