Level and distribution of DDT in surface soils from Tianjin, China

One hundred and eighty eight surface soil samples were collected from the Tianjin area to study the contamination of DDT and its metabolites. Measurements were taken for p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDE, o,p'-DDD and o,p'-DDT for all samples. The results indicated that p,p'-DDT and p,p'-DDE were the predominant contaminant compounds in the surface soil samples, with mean concentrations of 27.5 and 18.8 ng g(-1) respectively. No significant differences in DDT concentrations were found between the soils from wastewater treated irrigated areas and other areas, suggesting that wastewater irrigation is not an important source of DDT in the area. However, the spatial distribution of soil DDTs levels in the area did correlate well with early direct application rates of pesticides. In addition, both pH level and organic carbon content are also known factors affecting the level of DDT and its metabolites. Although it was assumed that the use of these chemicals was banned in the early 1980s, the current concentration levels appear to be too high to be mere residuals after 20 years degradation.     

Study on the investment value and investment opportunity of renewable energies under the carbon trading system

China has promised to start the national carbon trading system in 2017. In the carbon trading system, the renewable energy projects may obtain additional benefits through the Certified Carbon Emission Reduction (CCER) trade. As the carbon price fluctuates along with the market conditions, such fluctuation enables the renewable power projects to acquire the rights of an option, i.e. it may contain an even higher value due to the uncertainties in the future. While making an investment decision, the renewable power companies may choose to make the investment immediately, or postpone the investment and accumulate more information to increase the return of investment; and for immediate investments, the return must be sufficient to exceed the potential value of a waiting option. To study the investment in renewable power projects subject to the fluctuation of carbon price, this paper adopts the trinomial tree model of real options to estimate the net present value (NPV) and real option value (ROV) of three types of renewable power projects; according to the decision-making rules of real options to defer, all the three types of projects will exercise the option to postpone the investment decision. This thesis also calculates the benchmark prices of the three types of renewable projects at different times, in the two situations of having no government subsidy and having the government subsidy, so as to determine the investment opportunity of a project. The benchmark price decreases gradually along with the increase of government subsidy, indicating that the government subsidy will stimulate the investment in renewable projects. The benchmark price also increases gradually along with the lapse of time, indicating that the uncertainty will increase together with the time span and thus requires an even higher carbon price to determine the investment opportunity. This thesis also analyzes the sensitivity of factors affecting the investment in renewable projects and draws the conclusion that the fluctuation of carbon price is positively related with the benchmark price of renewable power projects, which indicates that the fluctuation of carbon price increases the option value of an investment but postpones the time of investment. As the China’s carbon trading system improves gradually, the carbon price will reach a stable status, thus stimulate the power companies to invest in the renewable projects.     

聚合硅酸氯化铝铁的制备及其絮凝性能

利用盐酸酸洗废液制备聚合硅酸氯化铝铁（PSAFC）,并用PSAFC处理造纸脱墨废水,考察了各种因素对絮凝效果的影响。实验结果表明：在废水pH为6、PSAFC加入量为240mg／L、搅拌转速为150r／min、搅拌时间为2min,静置时间为25min的条件下,COD、浊度、色度的去除率分别为87．2％,99．2％,94．5％;PSAFC的絮凝效果明显好于市售的聚合氯化铝和聚合氯化铁.     

氢氧化钾生产废水的膜处理技术改进

采用膜分离集成新工艺,对氢氧化钾生产废水传统处理工艺进行改造.通过改进离子交换树脂再生技术,去除废水污染物;增加预处理措施,延长离子膜的使用寿命;采用超滤-纳滤-反渗透工艺,降低能耗;清污分流,减少废水排放量;调控除硝工艺中氯化钡用量,解决重金属的累积问题.处理后的淡水作为循环水补充用水,浓缩水用于生产过程溶解氯化钾.     

Distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface water and sediments from Baiyangdian Lake in North China

Persistent organochlorine compounds, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs) were analyzed in surface water and sediments from Baiyangdian Lake, North China. Total concentrations of HCHs, DDTs and PCBs in surface water were in the range of 3.13-10.60, 4.05-20.59 and 19.46-131.62 ng/L, respectively, and total concentrations of HCHs, DDTs and PCBs in sediments were 1.75-5.70, 0.91-6.48 and 5.96-29.61 ng/g dry weight, respectively. Among the groups of HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) and DDTs (sum of DDT, DDD and DDE), the predominance of β-HCH, DDE and DDD in water and sediment samples was clearly observed. This observation suggested that β-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD. For PCBs, penta-, hexa- and hepta-chlorinated congeners were the most abundant compounds in the both phases. Furthermore, the partitioning of chlorinated compounds between sediment and water was investigated to understand their transport and fates in aquatic ecosystems. The results indicated that average logs of organic carbon-normalized sediment-water partition coefficients (logK_oc') for OCPs varied between 3.20 and 5.53, and for PCBs, logK_oc' values ranged from 3.19 to 5.57. The observed logK_oc' was lower than their equilibrium logK_oc predicted from linear model, which may be attributed to the solubility enhancement effect of colloidal matter in water phase and the disequilibrium between sediment and water.     

地质灾害防治集对论优态共存准则

地质灾害是威胁人民生命与财产安全、影响经济社会可持续发展的重大问题.我国是世界上地质灾害最严重的国家之一,加强地质灾害防治关乎国计民生.地质灾害是自然作用和人类活动影响下地质环境恶化的结果,其孕育与发展受多重因素制约,过程具有诸多不确定性,给灾害预警及防灾减灾带来影响.借助系统工程中处理不确定性的"集对分析"理论,剖析了地质灾害防治中相关因素及其作用与转化,探讨了系统不确定性的分析与处理方法,提出了地质环境开发利用与生态环境保护相互协同的优态共存准则,以助于有效保障人与社会的安全和发展,并为灾害学研究提供有益借鉴.     

基于人工神经元网络的滑坡稳定性预测评价

由于滑坡岩土体的结构与物理力学性质表现在宏观和微观上有着不连续性和高度的非线性等特点,其稳定性受地质因素和工程因素等综合影响,岩土体变形、演化规律的非线性和内在因素的非线性决定了滑坡是一个复杂多变的非线性系统.根据滑坡失稳的非线性特征,将人工神经元网络BP模型应用到滑坡稳定性的评价预测中,借助MATLAB的人工神经元网络工具箱,以国道G324上的86个滑坡数据为训练和预测样本对模型进行了实验和验证,结果表明,所建立的滑坡稳定性预测方法具有较高的预测精度.     

中国天然水体中五氯酚的浓度水平、管理及来源分析

五氯酚(PCP)属内分泌污染物,也是可对生物产生复合毒性的有机污染物。五氯酚及其钠盐曾被用作杀螺剂在我国血吸虫病流行疫区大范围长时间使用。为了解PCP在中国水环境中的污染现状,在阐述中国PCP的生产使用状况基础上,重点论述中国水环境介质中PCP的污染分布及影响因素。中国多地河流水环境中均存在PCP,其中沿长江流域的长江、洞庭湖、鄱阳湖PCP残留量较高,虽均在限值范围内,但PCP污染范围有从主要江河、湖泊等向沿海海域蔓延的趋势。PCP使用历史、用药区域类型、区域PCP消耗量等均会影响PCP的残留量,血吸虫病疫区PCP残留量明显高于对照区,在PCP及其钠盐显著减少使用后(2003年以后),施药历史仍然影响着水体介质中PCP的残留情况,PCP虽已停用,但其对环境所造成的不良影响还在持续。与国外研究相比,我国水环境介质中的PCP污染偏高且有上升趋势,这可能与部分区域近年来重现血吸虫病后施药控制有关。未来一段时期内有关PCP及其环境副产物在环境介质中的迁移转化规律、人群暴露评估、污染介质修复技术以及其替代品的研制都将是研究重点领域。     

松嫩平原芦苇湿地退化与修复过程中土壤细菌和甲烷代谢微生物的群落结构

湿地是全球CH₄重要的源与汇.受人为活动和气候条件影响,我国湿地退化严重,相关部门近年来已逐步开展湿地生态修复的工作.为研究湿地退化与修复过程中细菌和甲烷代谢微生物群落结构的响应,以松嫩平原芦苇湿地为研究对象,采集原始未退化芦苇湿地土壤、退化的和正在修复的芦苇湿地土壤,采用基于细菌16S rRNA基因、产甲烷菌mcrA基因和甲烷氧化菌pmoA基因的高通量测序技术研究细菌和甲烷代谢微生物的多样性和群落组成.结果表明,芦苇湿地退化导致土壤细菌和产甲烷菌的α多样性降低,甲烷氧化菌的α多样性升高,而细菌和产甲烷菌的α多样性与土壤含水率呈显著正相关关系,含水率越高的湿地土壤产甲烷菌的多样性也越高.原始未退化芦苇湿地土壤中细菌Rhizobiales和产甲烷菌Methanobacteriaceae的相对丰度较高;湿地退化导致根际促生菌Rhizobiales的相对丰度下降,致病菌Burkholderiaceae、耐污染细菌Sphingomonas、抗辐射细菌Rubrobacter以及Type Ⅰ型耐受极端环境的甲烷好氧氧化菌Methylobacter、Methylomonas和Methylococcus的相对丰度上升;正在修复的芦苇湿地土壤中细菌Bacillus和产甲烷菌Methanosarcinaceae、Methanomicrobiaceae以及Type Ⅱ型甲烷好氧氧化菌Methylocystis的相对丰度较高.因此,不同的芦苇湿地状态可以间接改变土壤性状进而改变湿地甲烷代谢菌群落结构.     

台风暴雨灾害风险区划更新实证分析

在缺失原始资料情况下,通过加权处理旧区划图和新的资料,是区划图更新的一个重要途径。以广东省台风暴雨灾害为例,说明如何应用加权更新模型进行区划图更新,并对其进行了检验。实例证明,在原区划理论和方法不变的情况下,通过加权处理新旧资料,可以满意地更新自然灾害风险区划图。