Interconversions and toxicity changes in hexachlorocyclohexane isomers on dispersion in water

Abstract

Studies on the transformations of hexachlorocyclohexane isomers, α‐, β‐, γ‐ and δ‐, in aqueous solution were carried out at 25 ± 1°C over a period of four weeks. Gas liquid chromatographic technique was used for analysis. The results indicated a loss as well as interconversion of all the four isomers with time. The resulting changes in toxicity of the aqueous solution were studied against Drosophila using topical application. Toxicity studies with aqueous solution of technical hexachlorocyclohexane were simultaneously carried out for comparison. Toxicity of the aqueous solutions of α‐, β‐, and δ ‐isomers showed an increase while that of the γ‐isomer decreased significantly during the four week experimental period. Aqueous solution of technical HCH was equally toxic as that of the γ‐isomer initially and did not show much decrease in its toxicity at the end. Changes in toxicity of the individual isomer solutions were considered to be due, in part, to interconversions of HCH isomers.     

2020年中国低碳经济发展前景研究

中国低碳经济发展涉及众多因素,区分这些因素对制定低碳政策具有重要意义.本文通过构建阻碍中国低碳经济发展影响因素的指标体系,采用图论方法建立影响因素的关联矩阵,运用布尔运算得到各影响因素的层级关系,得出低碳经济发展的主要影响因素为经济粗放式发展、居民低碳意识淡薄和缺乏低碳专业人才.根据主要影响因素从基础情景、低碳情景和受挫情景定量模拟了中国2020年低碳经济发展水平,预测结果表明,在低碳情景下2020年能源消耗总量大致是41亿吨标准煤,C02排放量23亿吨碳当量,煤炭占一次能源需求量的60.5%,石油占18.4%,天然气占7.5%,核能占3.3%,水能占8.5%,其它新能源占2.1%.从终端能源使用部门来看,第二产业尤其是高耗能行业比重大幅下降,现代服务业比重提高,对能源需求下降起到至关重要的作用.但是随着我国经济发展和居民生活水平不断提高,居民能耗呈现不断上升的特点,因此提高居民低碳意识和倡导低碳消费有利于实现我国低碳目标.此情景模拟取得了较好的预测效果,对中国的低碳经济发展政策具有一定的借鉴意义.     

中国CO《,2》排放的影响因素分解与预测

我国正处于2008年美国金融危机影响下,刺激经济一系列政策的落实观测期,要实现单位国内生产总值CO<,2>排放的目标,任务十分艰巨.本文采用投入产出结构分解技术,对1997-2004年我国应对亚洲金融危机时期的CO<,2>排放量变动进行了7因素的分解测算,结果表明经济增长是CO<,2>排放上升的主要驱动力,能源节约是驱动我国CO<,2>排放下降的主要因素,经济结构变动的影响相对较小.特别,国内最终需求、出口成长以及出口结构变动均推动CO<,2>排放上升,国内最终需求结构变动以及能源替代表现出了对CO<,2>排放的抑制影响等.同时,在我国经济"三步走"目标的前提下,结合能源节约设计了CO<,2>排放的3类情景,给出了未来CO<,2>排放的态势预测,提出了加强需求结构调整、能源效率提高以及可再生能源开发利用的保增长与CO<,2>减排并行不悖的建议.     

中国环境污染损失测算及成因探析

环境问题备受关注,环境污染严重影响中国经济的增长质量.本文采用治理成本法测算了1989 -2008年中国环境污染造成的经济损失,利用环境污染经济损失数据,采用协整理论研究了中国环境污染损失与经济增长之间的关系.研究表明,我国经济总量与环境污染之间存在长期均衡关系,经济增长是造成环境污染的基础性原因,并且环境污染状况随经济增长仍有扩大的趋势,至今尚未出现环境库兹涅茨曲线拐点的迹象.然后,本文从产业结构、能源结构和效率角度揭示了环境污染的结构性成因.研究认为,高污染行业在整个国民经济中比重过大是造成环境污染的产业结构方面的成因;以煤炭为主的能源消费和高耗能产品增长过快是造成环境污染的能源结构成因;能源效率低下是造成环境污染的技术性成因;资源能源价格长期偏低和法律法规滞后是造成环境污染的制度性缺陷.最后,针对问题提出,只有切实转变经济增长方式,突出技术创新、健全市场机制、完善环境法规才是解决环境污染问题的根本出路.     

地铁乘客火灾应激反应过程模型构建与分析

为提高地铁乘客的火灾应对能力,基于应激反应模型,构建地铁火灾应激反应过程理论模型;收集357份有效问卷数据,采用因子分析和结构方程模型(SEM),探讨个体特性、特定情境、认知评价、社会支持、应对方式和应对结果6个变量及变量各维度之间的相互影响关系.研究结果表明:个体特性可以正向调节心理反应结果,特定情境变量可以反向调节...     

Imputing Unmeasured Explanatory Variables in Environmental Epidemiology With Application to Health Impact Analysis of Air Pollution

This paper presents the results of a reconsideration of earlier work that finds an association between daily hospital admissions for respiratory distress and daily concentrations of sulphate (lag 1) as well as daily maximum concentrations of ozone (lags 1 and 3). These associations are found even after clustering the data by hospital of admission and accounting for the effects of temperature. We use an adaptation of their generalized estimating equation technique for clustered data, that daily data being for southern Ontario summers from 1983 to 1988. Like them, we adjust for daily maximum temperatures. However, unlike the earlier work returned to ours includes daily average humidity as a potential explanatory variable in our model. Our analysis also differs from theirs in that we cluster the data by census subdivision to reduce the risk of confounding pollutant levels with population size within regions. Moreover, we log-transform the explanatory variables and then high-pass filter the resulting data. We also deviate from the earlier analysis by taking account of measurement error incurred in using surrogate measures of the explanatory variables. To do so we use new methodology designed for our study but of potential value in other applications. That methodology requires a spatial predictive distribution for the unmeasured explanatory variables. Each day about 700 missing measurements for each of these variables can then be imputed over the geographical domain of the study. With these imputations we get a measure of imputation error through the covariance of the predictive distribution. Along with the predictive distribution we require an impact model to link-up with the predictive distribution. We describe that model and show how it uses the imputed measurements of the missing values of the explanatory variables. We also show how through that model, uncertainty about these values is reflected in our analysis and in commensurate uncertainties in the inferences made. Apart from its substantive objectives, our analysis serves to test the new methods with the earlier results serving as a foil. The reassuring qualitative agreement between our findings and the earlier results seems encouraging.     

世纪之交土壤学研究的挑战和契机──从第16届世界土壤学大会看土壤学的未来

第１６届国际土壤学大会包括全会和４５个分会,内容涵盖土壤学所有分支并反映了本世纪土壤学的进展。本文综述了土壤学在全球资源与环境问题中的重要地位,分析了世纪之交土壤学面临的挑战和契机,提出土壤学只有拓展与其它学科以及社会的联系,服务于社会的可持续发展,保持自己的特色并在基础研究和应用研究中不断创新,才能在未来更好地生存和发展。     

1995～2000年河西走廊土地利用变化研究

目前,人类面临的许多环境问题都与土地利用/覆被变化有关。利用1995和2000年两个时期的Landsat5的4、3、2(RGB)波段合成影像的解译结果,采用中国科学院资源环境数据库中的全国1∶100000土地资源利用分类系统,基于GIS软件平台ArcInfo7.1中文版对河西走廊近5年来的土地利用变化进行了研究。结果表明,近5年来,河西走廊发生了大规模的土地利用变化:①土地利用类型斑块数量和总边缘长度基本呈增加之势,表明研究区内景观的破碎程度增加;②土地利用结构变化表现出耕地、林地和建设用地有明显增加,水域、草地和未利用地都呈减少趋势,反映出区域城镇化进程的加快和生态环境恶化的趋势;③土地利用变化的区域差异明显,表现为地处河西走廊西段的酒(泉)嘉(峪关)地区以耕地、林地、水域和建设用地增加,未利用地和草地减少为主要变化特点,走廊中段的张掖市以耕地、林地和建设用地增加,草地、水域和未利用地减少为主要变化特点,走廊东段的武(威)金(昌)地区以耕地和建设用地增加,草地和水域减少为主要变化特点。     

气候变化下中国粮食和水资源的风险分析

介绍了全球气候变化对环境经济影响的复杂性研究的基本框架及模型,给出了用这些模型对中国经济安全模拟的结果。结果表明,全球气候变化条件下,若不考虑不确定性,中国的粮食安全是可以保证的;若考虑不确定性,则在最严重的情况下,中国未来的粮食生产存在7％－8％的缺口。采用最大强度开源的方法,在全球气候变化和保持原有产业结构的条件下,要实现我国2030年的经济目标是不行的。但是,通过调整产业结构,降低单位产出水耗,在保证水资源安全的条件下则是可行的。     

Sensitivity of the Structural Characteristics of Tree Rings to Climatic Changes in Different Climatypes of Scotch Pine

Radial increment and tree-ring structure were studied in the progenies of 16 climatypes growing in the southern taiga subzone. The coefficients of correlation between tree-ring parameters of the local and other climatypes were as high as 0.7–0.9, and the synchronism coefficients were higher than 0.7. Climatypes of northern origin were an exception. The sensitivity of the parameters of the tree-ring late wood decreased with an increase in the latitude at which the seeds for establishing the cultures were collected. Estimation of Euclidean distances in the space of tree-ring parameters showed that the northern climatypes differed from the southern taiga types by no more than 15%. The climatypes from the middle taiga and the forest–steppe exhibited smaller differences (10–11%).