Effect of alkaline earth metal promoter on catalytic activity of MnO2 for the complete oxidation of toluene

Herein, Na⁺ and Ca²⁺ are introduced to MnO₂ through cation-exchange method. The presence of Na⁺ and Ca²⁺ significantly enhance the catalytic activity of MnO₂ in toluene oxidation. Among them, the Ca-MnO₂ catalyst exhibits the best catalytic activity (T₅₀ = 194°C, T₉₀ = 215°C, E_a = 57.2 kJ/mol, reaction rate 8.40 × 10^?10 mol/(sec?m²) at 210°C. T₅₀ and T₉₀: the temperature of 50% and 90% toluene conversion; E_a: apparent activation energy) and possess high tolerance against 2.0 vol.% water vapor. Results reveal that the increased acidic sites of the MnO₂ sample can enhance the adsorption of gaseous toluene, and the mobility of oxygen species and the content of reactive oxygen species in the catalyst are significantly improved due to the formed oxygen vacancy. Thus these two factors result in excellent catalytic performance for toluene oxidation combining with the weak CO₂ adsorption ability.     

Particle Surface Hydrophobicity and the Dechlorination of Chloro-Compounds by Iron Sulfides

Halogenated aliphatic compounds (HACs) can be reduced by iron sulfides in aqueous systems. Generally, the thermodynamics and kinetics of dehalogenation reactions are controlled by the mineralogical and particle surface characteristics of the iron sulfide, the composition of the HAC and reaction conditions such as component concentrations, pH and Eh. In this theoretical and experimental investigation of CCl₄ and C₂Cl₆ reduction by FeS and FeS₂, the roles of hydrophobic and hydrophilic sites on the iron sulfides were analyzed. Experimental data obtained through zeta potential measurements, were used along with the Gouy-Chapman model and the simple two-layer surface complexation model to relate iron sulfide surface hydroxyl densities to the degree of HAC dehalogenation. The surface hydroxyl site densities of FeS and FeS₂ were found to be 0.11 sites/nm² and 0.21 sites/nm², respectively. During the dehalogenation reaction process, CCl₄ was found to decrease to its first intermediate product CHCl₃ within the first 20 hours followed by a slower process of conversion to CH₂Cl₂. The results also show that FeS is less hydrated (more hydrophobic) than FeS₂. For CCl₄ and C₂Cl₆, FeS is a better dehalogenator than FeS₂. These results imply that particle surface hydrophobicity is a critical factor in surface-mediated dehalogenation of chlorinated compounds.     

对开发建设项目环境影响评价中公众参与内容的探讨

环境影响评价中公众参与的内容应与建设项目的生产性质、污染状况相适应。不同类型的开发建设项目开展的公众参与内容是不同的。对项目公众参与的组织形式及内容进行了探讨，便于指导建设项目的环境影响评价工作。     

Fisher法确定稳定分类数

对Fisher法确定稳定分类数作了一些改进,提出利用β值指标来衡量分类的稳定程度,进而确定合理的分类个数。在实际应用中,证明了该方法是可行的。     

Bioaerosol emissions variations in large-scale landfill region and their health risk impacts

● The airborne bacteria in landfills were 4–50 times higher than fungi. ● Bioaerosols released from the working area would pose risk to on-site workers. ● The safe distance for the working area should be set as 80 m. Landfills are widely complained about due to the long-term odor and landfill gas emissions for local residents, while the bioaerosols are always neglected as another threat to on-site workers. In this study, bioaerosols samples were collected from the typical operation scenes in the large-scale modern landfill, and the emission levels of airborne bacteria, pathogenic species, and fungi were quantified and co-related. The corresponding exposure risks were assessed based on the average daily dose via inhalation and skin contact. It was found that the levels of culturable bacteria and fungi in all landfill samples were around 33–22778 CFU/m³ and 8–450 CFU/m³, and the active-working landfill area and the covered area were the maximum and minimum emission sources, respectively, meaning that the bioaerosols were mainly released from the areas related with the fresh waste operation. Acinetobacter sp., Massilia sp., Methylobacterium-Methylorubrum sp. and Noviherbaspirillum sp. were the main bacterial populations, with a percentage of 42.56%, 89.82%, 70.24% and 30.20% respectively in total bioaerosols measured. With regards to the health risk, the health risks via inhalation were the main potential risks, with four orders of magnitude higher than that of skin contact. Active-working area showed the critical point for non-carcinogenic risks, with a hazard quotient of 1.68, where 80 m protection distance is recommended for on-site worker protection, plus more careful protection measures.     

污染场地风险管控可持续评价指标体系构建及关键影响因素分析

以可持续发展理论和风险管理理念为基本原则的污染场地可持续风险管控已成为当前国际社会场地管理的重要决策问题和研究前沿热点,为明确影响污染场地风险管控可持续发展能力的决定性因素,基于国内外污染场地可持续风险管控相关文献的系统调研,构建契合我国场地管理背景的区域污染场地风险管控可持续评价体系,通过指标综合权重计算判定影响风险管控可持续发展能力的关键因子.结果表明,区域尺度上可能影响我国污染场地风险管控可持续性的指标多达44个,涵盖环境、社会、经济和技术这4个维度,单指标影响程度为0.26%～5.01%(平均值2.27%).潜在风险和温室气体排放(环境指标)、健康与安全和公众参与(社会指标)、管控成本和环保投资(经济指标)、修复周期和修复效果(技术指标)是影响我国污染场地风险管控可持续发展的重要因子,影响程度为1.89%～5.01%(平均值3.58%).具有较强政策敏感性的指标,包括考核指标、投融资创新、名录管理、能力建设、安全利用和制度建设等,对风险管控可持续性已经产生1.18%～3.48%的正向影响,随着政策制度的深入落实与全面地域推广,其对风险管控可持续发展的助力效应将更加明显.     

ERT技术在无机酸污染场地调查中的应用

利用高密度电阻率法对硫酸废液污染的场地进行污染调查,由于硫酸废液侵入土壤,使其介质的溶质浓度发生了改变,导致SO₄2-与地表潜水作用,电传导性提高,被污染土壤含盐量增加,但是电阻率降低与未被硫酸废液侵入的土层形成了一定的电性差异. 通过二维和三维电阻率层析成像(ERT)技术,圈定硫酸废液侵入土壤中的分布范围、侵蚀深度以及扩散羽流等,并对ERT结果进行土工试验异常验证. 结果表明:硫酸废液污染土壤的视电阻率小于6.0 Ω·m,污染区域长度达25.0 m,深度约4.0 m;地表土污染长度为12.0 m,表面宽度约4.0 m,污染土壤的总体积约为222.0 m3.      

杭州城市热岛空间分布及时域-频域多尺度变化特征

利用杭州20个自动气象站逐时数据计算2006年四季各站平均热岛强度,用薄盘样条函数法研究杭州城市热岛的空间变化,发现:夏秋季时较强,而春冬季强度较弱;总体趋势是杭州市丰体城区最大,向外辐散,逐渐减弱.利用2006年2月～2007年2月逐时气象数据,结合Morlet小波变换方法分析了杭州热岛周期变化特征,发现:其在频域上具有多尺度的周期振荡,尺度主要是24 h(日)、168 h(周)和1 490 h(2月).以日为周期的热岛强度与局地气候系统、地面长波辐射、近地层热量交换、人为热的日周期变化有关;而以周为周期的热岛强度变化成因主要与人类活动及城市大气污染物排放的"周末效应"有显著的关系;以2个月为周期的变化特征与一些较大尺度的自然变化相关.结果表明,杭州城市热岛时空变化是天气系统、地面长波辐射、下垫面、大气污染、人为热、人类活动、近地层热量交换等共同作用的结果.     

Medical geochemistry research in Spišsko-Gemerské rudohorie Mts., Slovakia

This study presents an assessment of the potential impact of geological contamination of the environment on the health of the population in Spišsko-Gemerské rudohorie Mts. (SGR Mts.). The concentration levels of potentially toxic elements (mainly As, Cd, Cu, Hg, Pb, Sb, and Zn) were determined in soils, groundwater, surface water, and stream sediments as well as in the food chain (locally grown vegetables). A medical study included some 30 health indicators for all 98 municipalities of the study area. The As and Sb contents in human fluids and tissues were analyzed in one municipality identified to be at the highest risk. Based on element content, environmental and health risks were calculated for respective municipalities. Out of 98 municipalities 14 were characterized with extremely high environmental risk and 10 were characterized with very high carcinogenic risk from arsenic (groundwater). Extensive statistical analysis of geochemical data (element contents in soils, groundwater, surface water, and stream sediments) and health indicators was performed. Significant correlations between element contents in the geological environment and health indicators, mainly cancer and cardiovascular diseases, were identified. Biological monitoring has confirmed the transfer of elements from the geological environment to human fluids and tissues as well as to the local food chain.     

USING REFERENCE SITES AND SIMPLE LINEAR REGRESSION TO ESTIMATE LONG‐TERM WATER LEVELS IN COASTAL PLAIN FORESTS1

ABSTRACT: The ability of regulators, resource managers, and consultants to assess accurately wetland hydrology is crucial when identifying and delineating wetlands. In this study, simple linear regression and long‐term (ten year) New Jersey Pinelands stream gaging and pitch pine lowland water‐level data sets were used to estimate long‐term hydroperiods at lowland test sites with short‐term (two year) records. Separate regression equations were developed for each test site using reference site data and stream gaging data, and two sets of equations for selected test sites were produced using two different short‐term periods of record. Test sites had long‐term records ranging from four to ten years, allowing validation of the regression models. Measured and predicted test site growing season water levels were similar regardless of which short‐term period of record was used. The results based on the stream gaging site data were similar, although the difference between measured and estimated growing season water levels was greater when this approach was used. Excellent agreement was found between measured and estimated frequencies of near‐surface saturation at test sites for each growing season month, and these relationships improved when cumulative, seasonal frequencies were considered. The reference wetland approach used in this study may have its greatest value in regions with both high development pressures and problem wetlands and may provide an effective way of resolving costly wetland delineation disputes.