城市垃圾问题及处理对策

中国的城市垃圾问题已经成为比较严重的环境问题之一,目前的垃圾处理存在很多问题.以全过程控制思想为基础,在可持续发展和"三化"原则的指导下,运用环境管理的经济、法律、行政等方法,提出解决城市垃圾问题的城市垃圾管理对策和技术对策,提出了城市生活垃圾多元化综合处理的设想,以求建立适合中国国情的城市垃圾管理体系和垃圾产业化体系.     

基于RuO2-IrO2/Ti和Fe0电极的电氧化-电絮凝处理含Tl废水

基于RuO₂-IrO₂/Ti形稳电极和Fe⁰牺牲电极实现电氧化-电絮凝(EO-EC)一体化处理含Tl (I)废水,并与单一的电絮凝(EC)进行比较,探讨了EO-EC处理含Tl废水的机理.结果表明,相较于单一EC,EO-EC (1:1)组合技术适应于宽pH (4-10)以及电流密度范围(5-20mA/cm²)下含Tl废水高效处理,且不易发生钝化;活性氯以及氧化还原电位在Tl (I)间接氧化Tl (III)过程中扮演重要角色,沉淀分析表明生成的Tl (OH)_3(s)与絮体Fe (OH)_3(am)共沉淀,纤铁矿位点可吸附残留Tl (I).EO-EC一体化技术可满足实际含Tl废水达标处理(<2µg/L)且具有经济可行性.     

An Approach for Evaluating the Effectiveness of Various Ozone Air Quality Standards for Protecting Trees

We demonstrate an approach for evaluating the level of protection attained using a variety of forms and levels of past, current, and proposed Air Quality Standards (AQSs). The U.S. Clean Air Act requires the establishment of ambient air quality standards to protect health and public welfare. However, determination of attainment of these standards is based on ambient pollutant concentrations rather than prevention of adverse effects. To determine if a given AQS protected against adverse effects on vegetation, hourly ozone concentrations were adjusted to create exposure levels that “just attain” a given standard. These exposures were used in combination with a physiologically-based tree growth model to account for the interactions of climate and ozone. In the evaluation, we used ozone concentrations from two 6-year time periods from the San Bernardino Mountains in California. There were clear differences in the level of vegetation protection achieved with the various AQSs. Based on modeled plant growth, the most effective standards were the California 8-hr average maximum of 70 ppb and a seasonal, cumulative, concentration-weighted index (SUM06), which if attained, resulted in annual growth reductions of 1% or less. Least effective was the 1-hr maximum of 120 ppb which resulted in a 7% annual reduction. We conclude that combining climate, exposure scenarios, and a process-based plant growth simulator was a useful approach for evaluating effectiveness of current or proposed air quality standards, or evaluating the form and/or level of a standard based on preventing adverse growth effects.     

Stricter Ozone Ambient Air Quality Standard Has Beneficial Effect on Ponderosa Pine in California

Ambient air quality standards and control strategies are implemented to protect humans and vegetation from adverse effects. We used a process-based tree-growth model (TREGRO) to show that over the past 37 years, changes in O₃ exposure, with accompanying variation in climate, are reflected in changes in the growth of Pinus ponderosa Dougl. ex Laws. in the San Bernardino Mountains near Los Angeles, California, USA. Despite variation in temperature and precipitation over the study period (1963–1999), O₃ exposure consistently reduced simulated tree growth. Simulated growth reductions increased concurrent with increasing O₃ exposure. The maximum growth reduction occurred in 1979. As O₃ exposures decreased during the 1980s and 1990s, effects on growth also decreased. This implies that emission control strategies taken to reduce exposures to attain O₃ standards benefited P. ponderosa growth in the San Bernardino Mountains. This modeling approach provides a powerful tool for solving the difficult problem of evaluating regulatory effectiveness by simulating plant response using long-term climate and air pollution exposure records for a given region.Phone 541 754-4621 Fax 541 754-4799     

Evaluation of ozone exposure indices in exposure-response modeling

In exposure-response modeling, a major concern is the numerical definition of exposure in relating crop loss to O3, yet few indices have been considered. This paper addresses research in which plant growth was regressed for soybean, wheat, cotton, corn, and sorghum against 613 numerical exposure indices using the Box-Tidwell model. When the minimum sum of squared errors criterion was used, optimum performance was not attained for any single index; however, near optimum performances were achieved by two censored cumulative indices and from a class of indices called the generalized, phenologically weighted, cumulative impact indices (GPWCIs). The top-performing GPWCIs accumulated concentrations, used sigmoid weighting schemes emphasizing O3 concentrations of 0.06 ppm (118 microg m(-3)) or higher, and had phenological weighting schemes with greatest weight occurring 20 to 40 days prior to crop maturity. These findings indicate that (1) peak concentrations are important, but lower concentrations should be included in the calculations, (2) increased plant sensitivity occurs between flowering and maturity, and (3) plants respond to cumulative exposure impact.     

泥石流灾情综合评估模式

泥石流灾情综合评估模式是在灾情绝对评估的基础上建立的。首先，建立了泥石流灾情评估的步骤框图；然后依据已有的泥石流灾情评估指标体系对各项指标进行量化分析处理，将得了各灾情评估指标公值分布及其量纲换算法，确定了反映直接损失的灾情绝对评估指标和相对评估指标（直接经济损失占灾区国民收入的比例），并对绝对和相对评估结果的等级进行了划分；最后，建立了绝对评估和相对评估结果对比的灾情综合评估模式。经过实例应用验证，评估结果能较好地反映灾情。     

海外耕地保护的社会化扶持对策及其启示

由于耕地为公众提供了大量的、具有强烈外部性的非生产性功能,很多国家都把耕地保护作为一个公共目标,并通过社会化扶持手段来得到实施.中国作为一个人多地少,人均耕地占有量低的国家,耕地保护任务更加突出,虽然"切实保护耕地"成为我国的一个基本国策,提出要执行"世界上最严格的耕地保护",并制定了耕地总量动态平衡、土地用途管制等一系列耕地保护政策,但耕地保护整体效果却不窖乐观,其中一个原因就是没有形成全社会共同保护耕地的氛围.本文对当今世界耕地保护社会化扶持的政策依据及实践手段进行综合与分析,并结合我国耕地保护的形势,提出了我国耕地保护社会化扶持的一系列对策措施,包括加快耕地产权制度建设,明确耕地保护的责任主体;重视耕地的非生产功能,提高全社会的耕地保护意识;采用综合优惠措施,激励农户的耕地保护行为;完善城镇发展规划,严格控制城镇对耕地的侵占;延长农产晶产业链,增加农业产业的经济收入.     

汕头红树林湿地表层沉积物环境因子对PAHs分布的影响

为了探明红树林湿地表层沉积物环境因子对多环芳烃分布的影响,野外采集了汕头红树林湿地表层沉积物样品,实验室内有机溶剂提取、氧化铝硅胶柱净化和气质联用分析了沉积物多环芳烃的质量分数、CHN元素仪分析了沉积物有机碳和黑碳的质量分数、激光粒度仪分析了沉积物的粒级组成,研究了沉积物有机碳、黑碳和粒度等各环境因子与多环芳烃的相关性.结果表明:有机碳与2～3环、4环和总多环芳烃的质量分数显著相关(P<0.05),表明表层沉积物有机碳的质量分数对PAHs的分布产生了显著的影响;黑碳与2～3环、4环、5～6环和总多环芳烃的质量分数显著相关(P<0.01),表明表层沉积物黑碳的质量分数对PAHs的分布产生了显著的影响;粘粒与2～3环多环芳烃的质量分数显著相关(P<0.05),与4环、5～6环和总多环芳烃的质量分数显著相关(P<0.01),表明表层沉积物粘粒的质量分数对PAHs的分布也产生了显著的影响;多元线性逐步回归分析显示,各回归方程黑碳的偏回归系数值都是最大,沉积物黑碳的质量分数对多环芳烃的质量分数贡献最大,表明黑碳是多环芳烃分布的主要影响因素.     

负载量对氨水吸收CO2的影响规律及添加剂的作用研究

进行了氨法脱碳过程中吸收剂中CO2负载量对CO2脱除率影响的实验研究.结果发现,CO2脱除率随着负载量的增大而显著减小,高负载量(≥0.4)时,增加吸收液中总氨质量分数(吸收液中所有包含氨分子和铵离子的物质,并统一换算成NH3的质量分数)并不能有效地提高CO2的脱除率.同时,分别对有机和无机添加剂进行筛选,选取哌嗪(PZ)和十二水磷酸钠(Na3PO4·12H2O)对吸收剂中高CO2负载鼍条件下的氨水溶液进行改性.实验结果表明,当哌嗪(PZ)浓度与总氨浓度之比为0.08,在吸收荆中CO2负载量为0.4、0.5和0.6的条件下,CO2脱除率可分别提高29.4%、31.0%和21.7%;当Na3PO4·12H2O浓度与总氨浓度之比为0.10,在吸收剂中CO2负载量为0.4、0.5和0.6的条件下,CO2脱除率可分别提高11.0%、11.7%和17.1%.