热分解技术在修复多氯联苯污染土壤中的应用

针对我国土壤中PCBs的污染特点,介绍了一种修复土壤的热分解技术,并详述了该技术的工作流程、影响因素、处理效率等问题。最后对该技术的发展趋势进行了展望,并对其在推广过程中可能遇到的困难进行了分析。     

用生物填料塔处理三甲胺废气

为解决废气中有机胺类物质的恶臭污染问题,采用自制生物填料塔处理三甲胺废气,考察了生物填料塔运行的主要影响因素及对三甲胺废气的净化效果。实验结果表明,在进气中三甲胺质量浓度为80.00mg/m3、气体流量为0.3m3/h(停留时间不小于30s)、循环液喷淋密度为0.5m3/(m2.h)的条件下,三甲胺去除率达99.9%,净化后气体能达到国家二级排放标准;生物填料塔对三甲胺的总去除量与容积负荷呈直线关系,相关系数达0.9949,表明三甲胺废气的生物净化效果显著。     

硫化法制备废水处理用光催化剂La3NbS2O5

采用高温硫化法制备了具有可见光活性的La3 NbS2 O5光催化剂,运用X射线衍射谱图、扫描电子显微镜照片、比表面积和紫外-可见漫反射光谱对La3 NbS2 O5的结构、物理性质和光吸收性能进行了表征.以亚甲基蓝为目标降解物,考察了硫化温度、催化剂加入量和制备方法对亚甲基蓝降解率的影响.实验结果表明,当硫化温度为800...     

广州近地面臭氧浓度特征及气象影响分析

利用2015年广州市近地面逐时臭氧(O_3)观测资料及气象数据,分析了广州地区近地面的O_3浓度时空分布特征及其与气象因子的关系.结果表明:广州地区城郊的O_3浓度高于中心城区;广州地区近地面的O_3浓度超标时间主要出现在4—9月,8月O_3浓度最高,3月O_3浓度最低;O_3浓度日变化呈现"单峰型"分布,早上7:00—8:00出现最低值,15:00达到峰值;O_3浓度与气温呈正相关,当气温高于30℃时,O_3浓度随温度升高增加明显;与相对湿度呈负相关,当相对湿度大于60%时,O_3浓度显著降低;当气压小于1010 hpa时,与气压呈负相关,当气压大于1010 hpa时,与气压呈正相关;当风力为2~3级吹西北偏西至西南偏西风区间时,O_3浓度最高,说明广州偏西部可能存在O_3污染源区;O_3浓度在晴天最高,其次是少云和多云天气,最低是在雨天.总体而言,气温高、日照长、辐射强、气压低、湿度小及2~3级的风力是广州地区近地面产生高浓度O_3的主要气象因素.当广州O_3浓度出现超标时,气温变化范围为25.9~37.4℃,相对湿度变化范围为29%~83%,气压变化范围为989.4~1009.1 h Pa,风速变化范围为0.7~5.8 m·s~(-1),紫外辐射强度日最大1 h均值最小为32.6 W·m~(-2),10:00—14:00均值最小为27.3 W·m~(-2).     

Estimating the variance in before-after studies

Problem

To simplify the computation of the variance in before-after studies, it is generally assumed that the observed crash data for each entity (or observation) are Poisson distributed. Given the characteristics of this distribution, the observed value (x_i) for each entity is implicitly made equal to its variance. However, the variance should be estimated using the conditional properties of this observed value (defined as a random variable), that is, f(x_i|μ_i), since the mean of the observed value is in fact unknown.

Method

Parametric and non-parametric bootstrap methods were investigated to evaluate the conditional assumption using simulated and observed data.

Results

The results of this study show that observed data should not be used as a substitute for the variance, even if the entities are assumed to be Poisson distributed. Consequently, the estimated variance for the parameters under study in traditional before-after studies is likely to be underestimated.

Conclusions

The proposed methods offer more accurate approaches for estimating the variance in before-after studies.     

高原山区城市重气泄漏扩散的风洞试验研究

进行重气泄漏扩散环境风洞试验,研究高原山区城市中重气泄漏扩散规律.结果表明,高原山区城市重气泄漏扩散存在1个危险风速,该风速下环境中重气浓度达到最大值,同时黏滞系数也达到最大值.通过多项式拟合可求出危险风速.当地年平均风速条件下,重气浓度随下风距离增加而减小,而在排放源下风向500 m外,随着距离的增加,重气浓度的变化趋缓;重气浓度在横风向上呈偏态分布;在垂直方向上随着高度的增加而减小,而高度超过20 m后重气浓度随高度的变化较小.     

溶藻细菌DC-L14的分离、鉴定与溶藻特性

从滇池蓝藻水华集聚区分离获得一株溶藻细菌DC-L14,经16S rDNA序列分析鉴定为Lysinibacillus fusiformis;小白鼠毒性试验初步显示该菌株未产生小白鼠中毒毒素;该菌能使铜锈微囊藻905聚集成团,沉于瓶底,最终黄化;该菌作用4 d,使惠氏微囊藻107、绿色微囊藻102、水华束丝藻和水华鱼腥藻的叶绿素a下降率最高为70.1%.最低为65.5%,平均为67.2%;当细菌处于稳定生长期时溶藻效果最强,共培养4 d能使铜锈微囊藻905的叶绿素a含量下降82.1%;离心沉降后检测,发现菌体本身无溶藻效果,而无菌上清液与原菌液溶藻效果相同,高温处理后的菌液溶藻能力增强,推测该细菌是通过分泌溶藻物质溶藻,该物质可能为非蛋白质类,高温可能有利于溶藻物质的释放.图4表1参25     

Contributing institutional factors of rural environmental pollution in the process of modernization in China —In the perspective of the efficiency of environmental management system

With the development of rural pollution, its characteristic and institutional factor should be studied for pollution control through economics and sociology. Based on the data gathered from investigations by several government sectors, rural environmental pollution can be divided into two types by its sources: internal source type and external source type. The internal source type is the main component of rural pollution at present, which can be further divided into three types. Research shows that the contributing institutional factors of rural pollution issues and the effectiveness of environmental management system over rural pollution can be summarized as distinctiveness. In essence, the rural pollution issue results from the dualism of rural and urban areas’ inadaptability to rural modernization. In detail, the contributing factors can be summed up on three institutional levels. There are obvious loopholes in rural environmental management system which, in the meantime, is incapable and inadaptable to rural pollution control. There exist similar questions in the related public service system, which are intensified by inappropriate reform which brought about incompatible incentive in the recent years. However, in the eleventh five-year plan period, there are advantageous trends in the three institutional levels.     

淮海经济区核心区污染排放对重点区域城市PM2.5贡献研究

基于WRF-CMAQ空气质量模型，采用开关污染源排放的敏感性试验方法，定量分析了淮海经济区核心区污染排放对京津冀区域、"2+26 "大气污染传输通道城市、汾渭平原地区和长三角区域PM_2.5的贡献.结果表明，对京津冀区域，污染贡献比例最大值出现在10月份，同时对不同城市的贡献值在10%以内变化；对" 2+26"大气传输通道城市，影响的时空差异变化明显，其中对聊城市、菏泽市和济南市的贡献值均超过了10%；对汾渭平原地区的贡献总体较弱，最大贡献值低于5%；对长三角区域，贡献值在不同城市间的时空差异变化明显.考虑到淮海经济区地处京津冀和长三角过渡地带，且对京津冀和长三角区域PM_2.5影响较大，建议尽快将淮海经济区核心地区纳入国家大气污染重点控制区.     

FeCl3改性污泥生物炭对水中吡虫啉的吸附性能研究

以脱水污泥为原料,制备污泥生物炭（SBC）和FeCl₃改性污泥生物炭（Fe-SBC）处理低浓度吡虫啉（IMI）废水（浓度为10 mg·L^-1）,考察SBC和Fe-SBC对IMI的吸附性能及影响因素,并探究其吸附机理.采用SEM、XRD、FTIR、BET及元素分析等探得污泥生物炭FeCl₃改性成功.Fe-SBC对IMI的最大吸附量为4.915 mg·g^-1,是SBC的1.97倍,表现出更好的IMI吸附性能.pH和离子强度的变化对Fe-SBC的吸附性能影响较小,最大波动幅度分别为4.4%和7.8%.两种生物炭对IMI的吸附均符合准二级动力学模型,Freundlich模型可以更好地描述其等温吸附曲线.热力学研究表明,SBC吸附IMI是非自发吸附,而Fe-SBC是自发吸附.Fe-SBC对IMI的吸附机理包括静电作用力、氢键作用力及π-π键相互作用力.多次热解再生后的Fe-SBC对IMI的去除率仍可达93.088%.