Adsorption-desorption characteristics of mercury in paddy soils of China

Mercury (Hg) has received considerable attention because of its association with various human health problems. Adsorption-desorption behavior of Hg at contaminated levels in two paddy soils was investigated. The two representative soils for rice production in China, locally referred to as a yellowish red soil (YRS) and silty loam soil (SLS) and classified as Gleyi-Stagnic Anthrosols in FAO/UNESCO nomenclature, were respectively collected from Jiaxin County and Xiasha District of Hangzhou City, Zhejiang Province. The YRS adsorbed more Hg(2+) than the SLS. The characteristics of Hg adsorption could be described by the simple Langmuir adsorption equation (r2 = 0.999 and 0.999, P < 0.01, respectively, for the SLS and YRS). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 111 and 213 mg Hg(2+) kg(-1) soil, respectively, for the SLS and YRS. Adsorption of Hg(2+) decreased soil pH by 0.75 unit for the SLS soil and 0.91 unit for the YRS soil at the highest loading. The distribution coefficient (kd) of Hg in the soil decreased exponentially with increasing Hg(2+) loading. After five successive desorptions with 0.01 mol L(-1) KCl solution (pH 5.4), 0 to 24.4% of the total adsorbed Hg(2+) in the SLS soil was desorbed and the corresponding value of the YRS soil was 0 to 14.4%, indicating that the SLS soil had a lower affinity for Hg(2+) than the YRS soil at the same Hg(2+) loading. Different mechanisms are likely involved in Hg(2+) adsorption-desorption at different levels of Hg(2+) loading and between the two soils.     

Characterizing effects of uncertainties in MSW composting process through a coupled fuzzy vertex and factorial-analysis approach

A coupled fuzzy vertex and factorial-analysis approach was developed in this study for systematically characterizing effects of uncertainties in a municipal solid waste composting process. A comprehensive composting process model was also embedded into the system framework and used to address substrate decomposition and biomass growth, as well as the interactions between moisture contents, temperatures, and oxygen concentrations. The applicability of the proposed method was verified through a custom-made pilot-scale composting system. Results from fuzzy simulation indicated that the fuzzy vertex method could effectively communicate implicit knowledge into dynamic simulations and thus provide valuable information for enhancing composting process control under uncertainty. The factorial analysis was effective in quantifying the proportion to which the uncertainty of each single or interactive effect of model parameters contributes to the overall uncertainty of the system outcomes. Thus, sensitive parameters that may lead to errors or unreasonable predictions can be determined. The proposed study system could not only be used in characterizing combined effects of uncertainties for composting processes, but was also applicable to many other environmental modelling systems.     

三种偶氮染料降解历程在紫外-可见光谱上的表现

本文对基本结构相似的三种偶氮染料橙黄Ⅱ、活性艳红Ｘ－３Ｂ和活性黑Ｋ－ＢＲ水溶液在铁粉还原－光氧化两步法处理中的紫外－可见光谱图作对比分析,依据其结构与特征吸收的关系,初步推测还原铁粉－光氧化法降解染料的历程。     

生产剩余与消费剩余：人与自然和谐的探索

人与自然的和谐是人类社会可持续发展的实践基础和核心议题。本文着重从“生产剩余”和“消费剩余”新的认识视觉 ,通过构建物流循环结构和剖析人与自然的相依关系 ,探索两者之间物质、能量转化的协同机理与和谐准则 ,进而提出了相应的实践对策。     

火电建设项目环境影响评价基础数据库建设方案与应用

针对火电建设项目环境影响评价的特点,提出了火电建设项目环境影响评价基础数据库的资料入库格式和内容要求。结合数据库的分类统计和GIS地理信息系统的空间分析功能,提出了基础数据库的数据处理与统计分析及数据库应用系统的建设方案,并得到初步应用。     

以“生态足迹”的方法衡量青藏高原可持续发展能力

通过论述青海西藏两地环境质量总体向好的结论引证青藏高原生态盈余。用"生态足迹"和"人类发展指数"两种指标来衡量青藏高原的可持续发展能力,结果表明青藏高原有着较好的生态盈余,但人类发展指数值偏低,限制了青藏高原的可持续发展能力。应通过提高公共服务能力,加强生态系统管理,减少碳足迹来实现青藏高原的生态文明。     

焦炉烟气中苯可溶物分析方法探讨

根据现有国家标准方法，通过改进实验条件，在保证了实验数据准确度的前提下，在样品量大和时间紧的情况下，可缩短回流时间，提高分析效率，作到保质保量。     

低温等离子体协同处理Hg~0、NO_x、SO_2的机理研究

低温等离子污染物处理技术具有工艺简单、可协同控制多种污染物、占地面积小等特点,是目前在污染物控制技术领域的研究热点。主要介绍气体放电产生低温等离子体去除污染物过程中存在的O2、CO2气体对污染物去除效率的影响、NO x和SO2对Hg去除效率的影响和加入H2O、NH3、HCl对污染物去除效率的影响研究。     

光合细菌及活性污泥法联用工艺处理明胶废水试验

研究了光合细菌(photo-synthetic bacteria,简称PSB)及活性污泥法联用工艺处理明胶生产过程中产生的高浓度有机废水的可行性。经过光合细菌及活性污泥先后次序的变换,得出了最优处理工艺。结果表明:"PSB+活性污泥"工艺、"活性污泥+PSB"工艺COD去除率平均值分别为94.7%和96.0%;"活性污泥+PSB"工艺有较强的去除钙质和耐冲击负荷的能力,该工艺适合处理此种含高钙、高氯、高碱明胶的废水。     

7B04铝合金海洋性大气腐蚀研究

通过在青岛和海南开展的7B04铝合金户外大气暴露试验,利用失重分析、形貌观察、断面分析和电化学交流阻抗谱等研究了7B04铝合金在海洋性大气环境中的腐蚀动力学规律和腐蚀特征。结果表明,在青岛和海南等海洋性大气环境中,7B04铝合金腐蚀初期以点蚀形式萌生,随后向均匀腐蚀发展;腐蚀过程均经历了腐蚀速率由高到低的过程,且腐蚀失重与时间的关系均可用幂函数显著回归;电化学阻抗谱分析表明当腐蚀产物足够厚时,7B04铝合金海洋性大气腐蚀的电化学过程由侵蚀性离子的扩散步骤来控制。