酸雨形成机制及其影响因素的探讨

本文概述了酸雨的形成机制及影响酸雨酸度的因素。重点探讨了致碱物质，如气体氨、含有Ca^2 、Mg^2 的碱性粒子以及海盐氯循环对酸雨的缓冲作用。     

暖风机的可靠性分析与改进

本文介绍了我国出口室内加热器类产品中暖风机在型式试验过程中常见的安全问题,指出其普遍存在的不符合标准的条款和产生的原因,并提出了解决问题的技术途径和预防措施.     

The effect of diesel fuel on common vetch (Vicia sativa L.) plants

When petroleum hydrocarbons contaminate soil, the carbon:nitrogen (C:N) ratio of the soil is altered. The added carbon stimulates microbial numbers but causes an imbalance in the C:N ratio which may result in immobilization of soil nitrogen by the microbial biomass, leaving none available for plant growth. As members of Leguminosae fix atmospheric nitrogen to produce their own nitrogen for growth, they may prove more successful at growing on petroleum hydrocarbon contaminated sites. During a wider study on phytoremediation of diesel fuel contaminated soil, particular attention was given to the performance of legumes versus other plant species. During harvesting of pot experiments containing leguminous plants, a recurring difference in the number and formation of root nodules present on control and contaminated Common vetch (Vicia sativa L.) plants was observed. The total number of nodules per plant was significantly reduced in contaminated plants compared to control plants but nodules on contaminated plants were more developed than corresponding nodules on control plants. Plant performance of Common vetch and Westerwold's ryegrass (Lolium multiflorum L.) was compared to illustrate any difference between the ability of legumes and grasses to grow on diesel fuel contaminated soil. Common vetch was less affected by diesel fuel and performed better in low levels of diesel fuel contaminated soil than Westerwolds ryegrass. The total amount of diesel fuel remaining after 4 months in Common vetch planted soil was slightly less than in Westerwolds ryegrass planted soil.     

Emergency management of reservoirs and water treatment plants in typhoon season: a case study of Ningbo

ABSTRACT

Coastal cities represented by Ningbo are directly or indirectly affected by typhoons each year. By analyzing the past three typical typhoons landing in Ningbo from 2013 to 2016, it was found that before and after the typhoon transit, reservoir and water treatment plant would be made by the destructive impact, including the increasing water level, water volume in a short time, and the deteriorating water quality. Among those, the water quality caused by typhoons increased the water treatment process load, the amount of water purification agents increased significantly, and the emergency response put a great pressure on the inventory of water plants. Based on the statistics and analysis of the basic parameters of the reservoir and water treatment plant during the typhoon season, the emergency management of the typhoon was divided into three situations, namely, pre-typhoon, typhoon period and post-typhoon. Thus, it is effective for the relevant practitioners of the reservoir and water plant to ensure the safe water supply during typhoon season.     

Temporal-spatial variability and fractal characteristics of soil nitrogen and phosphorus in Xinji District, Hebei Province, China

Traditional statistics, geostatistics, fractal dimensions, and geographic information systems (GIS) were employed to study the temporal?Cspatial variability of soil total nitrogen (TN) and total phosphorus (TP) levels in Xinji District, Hebei Province area of the North China Plain from 1980 to 2007. The results indicate that nutrient levels follow normal or lognormal distributions. The TN content was 0.59 ±0.155 g kg^???1 in 2007, an increase of 0.44 g kg^???1 compared with that of 1980. In 2007, the TP content was 1.21 ±0.227 g kg^???1, an increase of 0.01 g kg^???1 from 1980. The geostatistical analysis showed that the distribution of these soil nutrients in the study area exhibits a trend and anisotropy. The range and [C ₀/(C ₀?+?C)] of TN and TP in 1980 were all less than in 2007. The ordinary kriging interpolation method was used to analyze the nutrient contents differences between 1980 and 2007. The results indicate that soil TN levels have increased over the 27-year period, and the area where the TN level had increased by at least 0.4 g kg^???1 was about 61.7% of the district. The area where the TP content increased covered about 58.4% of the district. The variance analysis indicated that land-use type had a clear influence on the distribution and change in TN and TP content. Using the 3-D box-counting dimension method combined with GIS, the fractal dimension of soil nutrient spatial distribution over the two periods showed that in 27 years, the fractal dimension of TN increased from 1.95 to 2.02, and the fractal dimension of TP increased from 1.89 to 2.01, indicating that the complexity of the spatial distribution of all nutrient contents had increased. This study can provide a basis for accurate fertilizing and to enhance the conversion of soil characteristics under different spatial scales.     

导流电解法处理含酚废水的研究

阐述了电解法处理废水的基本原理。通过试验确定了用该法处理含酚废水的最佳工艺条件,出水的酚浓度、pH均达到国家排放标准。该法工艺过程简单,处理效果好,无二次污染。经济分析结果表明,该法处理含酚废水的费用低于传统的电解法。     

SiO2掺杂对V2O5-WO3/TiO2脱硝催化性能的影响

采用溶胶凝胶法制备TiO2-SiO2载体,浸渍法制备出V2O5-WO3/TiO2-SiO2催化剂,利用BET、FESEM、XRD、TGA和激光拉曼对催化剂进行表征,研究催化剂的理化性质。以NH3为还原剂,考察反应温度、SiO2掺杂量、焙烧温度、空速和使用时间对SCR催化还原NO的性能影响。结果表明,V2O5-WO3/TiO2-SiO2催化剂最佳反应温度在250~350℃。SiO2掺杂能提高活性组分V2O5和WO3在载体表面的分散性,制备出的催化剂具有更大的比表面积和更宽的温度区间,提高脱硝活性及稳定性。SiO2掺杂量对催化剂性能影响较大,制备的催化剂中,TiO2/SiO2=2显示了最大催化活性,脱硝率均在60%以上,TiO2/SiO2=0.5制备的催化剂稳定性最差。焙烧温度对催化剂性能也有影响,焙烧温度在500和600℃时,最低脱硝率为58%和23%,最佳焙烧温度为400℃,脱硝率均在80%以上,具有优越的脱硝性能。实验结果还表明,空速对V2O5-WO3/TiO2-SiO2催化剂的影响不大,在20 000 h-1空速下催化剂的使用时间对脱硝率的影响也不大,48 h内能保持在99%左右,非常稳定。     

电渗析技术的新进展

电渗析技术是膜分离技术之一 ,由于具有高效、低能耗等特点已经被多个行业广泛使用。本文阐述了几种新的电渗析技术 ,包括无隔板电渗析、填充床电渗析、双极膜电渗析等 ,并探讨和综述其研究现状和发展前景。     

微分脉冲阴极溶出伏安法测定环境水样中的痕量硒

采用微分脉冲阴极溶出法测定环境水样中的痕量硒,以银电极为工作电极,在酸性介质0.06mol.l^-1HCl-0.07mol.l^-1HNO3溶液中于－0.35V(vs SCE)处富集20min,使Se(IV)电沉积为硒化银,然后,以40mV.s^-1的扫速,在碱性介质2．0mol.l^-1NaOH溶液中阴极溶出至－1.2V(vsSCE),硒化银被还原为银的溶出峰电位约为－0.85V(vs SCE),硒的分析校正曲直到40ng.ml^-1仍然成线性,检测下限为11.5pg.ml^-1,相关系为0.9982,灵敏度为10.93uA/ng.ml^-1,20ng.ml^-1的RSD（n=5)为1．26％,检出限（3σ为3.46pg.ml^-1,环境水样中常见离子的存在不干扰痕量硒的测定。     

制备工艺对V2O5/TiO2 SCR催化剂脱硝性能的影响

围绕SCR脱硝催化剂制备工艺中活性组分负载顺序和钒助溶剂2个关键因素,分别制备了钒钨体系和钒钼体系催化剂,比较了不同条件下制备的催化剂的脱硝活性,并利用X射线光电子能谱分析（XPS）、程序升温还原（H2-TPR）和程序升温脱附（NH3-TPD）等手段进行表征。结果表明,活性组分与助剂同时负载制备的催化剂,其低价钒和化学吸附氧的比例最高,钒的还原温度最低,酸性位数量最多,表现出最好的脱硝活性;相较于常规助溶剂单乙醇胺,以草酸为助溶剂制备的催化剂,其低价钒和化学吸附氧比例更高,氧化还原性能和表面酸性更强,脱硝活性更好。