三峡库区消落带土壤中硫酸盐还原菌对汞甲基化作用的影响

为探究三峡水库这一特殊的周期性干湿交替环境中,硫酸盐还原菌(sulfate-reducing bacteria,SRB)是否在汞的生物甲基化过程中起主导作用,本文以库区消落带原土为研究对象,以灭菌土+接种硫酸盐还原菌Desulfovibrio africanus(D.africanus,DSM-2603)为对照(试验A),在每公斤土壤分别添加0、1、5 mg汞浓度条件下,模拟研究原土(试验B)中总汞(THg)和甲基汞(MeHg)含量的动态变化、总硫酸盐还原菌(SRB)数量变化,以及影响土壤中甲基汞含量的环境因子分析.结果表明,淹水状况有利于THg从土壤中释放,且Hg含量越高,释放越快;菌株D.africanus对汞具生态适应性,其菌数与MeHg含量显著正相关:在5 mg·kg~(-1)Hg条件下,D.africanus菌数可达3.65×10~4cfu·g~(-1),MeHg含量也高达7.60×10~4ng·kg~(-1).值得注意的是,试验B处理中,一方面消落区原土中SRB菌数较少,平均仅193 cfu·g~(-1);另一方面,土壤MeHg含量较低:在5mg·kg~(-1)Hg条件下,MeHg含量仅为5.54×10~3ng·kg~(-1),且总SRB菌数与MeHg含量无显著相关性.由此可以推测,在三峡水库消落区这种非严格厌氧土壤环境中,SRB并非优势菌群,其中还存在着其它对生物汞甲基化起主导作用的好氧或兼性厌氧微生物种群.     

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH₂OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl₂ extractable fraction. A large proportion of Cu was bound to the acidic H₂O₂ extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier’s procedure, and the order of mobility was Zn > Cd > Cu  > Pb.     

基于Bayes误差修正的我国能源消费需求组合预测研究

鉴于能源需求系统的复杂性，为了更科学地分析相关经济因素的变化对我国能源需求的影响效应，本文首先利用通径分析法分析了能源需求的主要影响因素及其对能源需求的直接与间接作用，结果表明经济增长、全国总人口、能源消耗结构是决定能源消费需求的主要因素，其中，经济增长为能源需求的主要决定因素，能源消费结构为能源需求的主要限制性因素。在此基础上，文章考虑了多重共线性和预测有效性问题，分别建立了偏最小二乘（PLS）及趋势外推的单一预测模型，然后基于最优组合预测理论建立了偏最小二乘（PLS）——趋势外推组合预测模型。最后，利用Bayes计理论得到了预测误差的概率分布和组合预测的区间估计。结果表明，利用预测误差的Bayes估计来修正组合预测的结果，将得到更为精确的结论。     

Cultural Relevance for Rural Community Development in China: A Case Study in Bai,Jingpo and Huyaodai Communities of Yunnan Province

Abstract

A three-year study over the Bai, Jingpo and Huayaodai communities in Yunnan Province reveals that the community development is significantly influenced in various ways by such cultural factors as the concepts of development; concepts and traditions of inter-community relationships, consumption, marriage and gender; patterns of decision-making and production, resource and income allocation; as well as the role of information dissemination systems, religion and ritual. Based on the analysis over the interactive relevance between each factor and community development, some strategies and methods for dealing with such a cultural relevance in development projects are recommended.     

废活性污泥破乳作用研究初探

利用污水处理厂的废弃活性污泥作为破乳剂，对柴油－水乳状液体系进行了破乳实验研究。结果表明，温度高时活性污泥的破乳效果好，水的脱除率可达９０％。在此基础上将活性污泥用溶剂进行抽提，提取液的破乳作用优于活性污泥。该法既能利用废活性污泥，还为替代化学破乳剂提供了可能性。     

桑蚕蛹资源及其综合开发前景

我国有桑蚕蛹资源５０万ｔ／ａ，干蛹蛋白质高达４８．９８％．氨基酸种类齐全，８种必需氨基酸占４１％。目前大部分蚕蛹仅作为饲料使用，高蛋白资源的浪费极大。蚕蛹可开发２０多种保健食品、纺织、轻化工产品．综合开发经济效益高．具有广阔的开发前景。     

城市可持续发展与城市政府职能

城市作为我国行政区划中重要单元和区域经济活动的中心,城市经济、社会发展直接关系着全国的发展水平,城市可持续发展在我国可持续发展中占有重要的地位。城市政府是推动城市可持续发展的首位力量。本文分析了城市可持续发展面临的主要问题,阐述了城市政府五大主要职能,探讨了城市可持续发展与城市经济社会职能的关系。     

坚持“三个不变”做好企业改制期间安全生产工作

武汉钢铁（集团）公司在改制期间针对安全工作出现的新情况,坚持“安全第一,预防为主”的方针不变,坚持以安全生产责任制为中心不变,坚持严格管理,严格考核不变,保证了改制期间的安全生产工作。     

开化县外向型创汇林业的战略模式

我国森林资源少,消耗量大,林业建设资金短缺。如何发展当前的林业生产、筹集林业建设资金,开化县的外向型创汇林业为我们走出了一条具有中国特色的外向型林业建设道路。本文就开化县发展外向型创汇林业的优点、出口创汇的主要对策、主要商品、发展潜力及其前景进行了论述,对目前正在探索适合我国国情的、解决我国林业“两危”的战略对策提供了现实的典型范例。