城市污泥好氧堆肥过程中DOM的光谱动态变化特征

跟踪监测了城市污泥堆肥工厂好氧堆肥的一个发酵周期,利用三维荧光光谱技术,结合平行因子分析法,研究了堆肥过程中DOM的动态变化过程.结果 表明,堆肥污泥中DOM主要由4种荧光组分组成,分别为类色氨酸(C1:275nm/350 nm)、类富里酸(C2:240 nm、315/415 nm)、类酪氨酸(C3:275 nm/305 nm)和类胡敏酸(C4:265 nm、360 nm/480nm).随堆肥过程推进,组分C1、C3所占比例先增大后减小,而组分C2、组分CA所占比例升高,表明堆肥腐殖化程度不断增强;由紫外-可见吸收光谱研究发现,SUVA254、SUVA280、A240 ～400逐渐增大,E250/ E365逐渐减小,表明DOM的芳香性和腐殖化程度逐渐增强.通过相关性分析可知,CA与吸收光谱参数在p ＜0.05水平上显著相关,表明CA可以作为评价堆肥腐熟度的指标.     

Can variations in visual behavior measures be good predictors of driver sleepiness? A real driving test study

Objective: The primary purpose of this study was to examine the association between variations in visual behavior measures and subjective sleepiness levels across age groups over time to determine a quantitative method of measuring drivers' sleepiness levels.

Method: A total of 128 volunteer drivers in 4 age groups were asked to finish 2-, 3-, and 4-h continuous driving tasks on expressways, during which the driver's fixation, saccade, and blink measures were recorded by an eye-tracking system and the subjective sleepiness level was measured through the Stanford Sleepiness Scale. Two-way repeated measures analysis of variance was then used to examine the change in visual behavior measures across age groups over time and compare the interactive effects of these 2 factors on the dependent visual measures.

Results: Drivers' visual behavior measures and subjective sleepiness levels vary significantly over time but not across age groups. A statistically significant interaction between age group and driving duration was found in drivers' pupil diameter, deviation of search angle, saccade amplitude, blink frequency, blink duration, and closure duration. Additionally, change in a driver's subjective sleepiness level is positively or negatively associated with variation in visual behavior measures, and such relationships can be expressed in regression models for different period of driving duration.

Conclusions: Driving duration affects drivers' sleepiness significantly, so the amount of continuous driving time should be strictly controlled. Moreover, driving sleepiness can be quantified through the change rate of drivers' visual behavior measures to alert drivers of sleepiness risk and to encourage rest periods. These results provide insight into potential strategies for reducing and preventing traffic accidents and injuries.     

典型岩溶地下河流域水体中硝酸盐源解析

地下河是岩溶地区地下水赋存运动的主要场所和重要水源,近年来,硝酸盐污染严重.为解析典型岩溶地下河流域水体中硝酸盐的来源,利用δ~(15)N-NO~-_3、δ~(18)O-NO~-_3和δ~(18)O-H_2O稳定同位素示踪技术开展研究,并通过SIAR稳定同位素模型,对不同污染源的贡献率进行了定量识别,同时阐明了土地利用类型对流域水体硝酸盐分布及来源的影响.结果表明:①降雨/化肥中的氨盐、土壤有机氮和粪肥污水是流域内水体硝酸盐的主要来源;②流域内水体硝酸盐的转化过程主要以硝化作用为主导,水体硝酸盐氮氧同位素初始值未受分馏影响;③基于SIAR模型,不同端元对流域内水体硝酸盐的贡献比例呈季节性差异,化肥、土壤有机氮和粪便污水对丰水期流域内水体硝酸盐的贡献比例分别为57.07%、 34.06%和8.87%;对流域内枯水期水体硝酸盐的贡献比例分别为34.14%、 33.02%和32.84%.     

POC的结构参数对DMCC发动机排放影响的试验研究

在一台直列4缸增压中冷电控单体泵柴油机的进气道上增加甲醇喷射装置,实现柴油甲醇二元燃料燃烧(DMDF)模式.利用废气分析仪对其主要气体排放进行测量,研究在排气管上加装的柴油颗粒氧化催化转化器结构参数对尾气催化效率的影响,试验结果表明:POC长度越长,对碳烟、THC、和未燃甲醇的转化效果越好,甲醇替代率为30%、POC长度为100 mm时,对碳烟、CO、THC和未燃甲醇的平均净化效率分别为15.00%、91.61%、75.56%、66.96%,长度增加至200 mm后,上述效率明显提高,分别提高到30.37%、99.29%、67.55%、95.44%;POC孔密度增加,POC对碳烟、CO及未燃甲醇的转化效率有小幅增加,甲醇替代率为30%时,孔密度从200目增加到300目,对碳烟、CO和未燃甲醇的催化效率分别从19.61%、94.66%、86.07%提高到23.06%、97.44%和88.56%;POC结构参数的改变对NO_x的转化效率影响不大.     

不同草本植物间作对Cd污染土壤的修复效果

为了研究不同草本植物间作对空心菜Cd吸收效果及污染土壤中Cd移除率的影响,采用盆栽试验,以空心菜茎叶Cd消减率与土壤中Cd移除率为主要指标,研究了空心菜在Cd污染土壤中单作及与10种草本植物（高丹草,苏丹草,狼尾草,黑麦草,苦卖菜,菊苣,籽粒苋,三叶草,紫花苜蓿,紫云英）间作的Cd积累效应与对Cd污染土壤的修复效果.结果表明：不同间作处理对空心菜茎叶与根中Cd含量有显著影响,其中,空心菜与高丹草、苏丹草、狼尾草间作后,空心菜茎叶Cd含量显著降低,空心菜茎叶Cd的消减率分别达到34.0%、35.8%、34.3%;菊苣、籽粒苋、三叶草、紫花苜蓿及紫云英与空心菜间作对空心菜茎叶Cd吸收有不同程度促进作用.间作的不同草本植物对土壤中Cd的吸收间有显著差异,地上部Cd含量范围1.81~12.87mg/kg,最大相差7.1倍;不同间作植物茎叶中Cd含量大小为：苦荬菜 > 菊苣 > 苏丹草≈黑麦草 > 高丹草≈狼尾草 > 紫花苜蓿≈籽粒苋 > 三叶草≈紫云英.不同草本植物与空心菜间作对土壤Cd移除率为0.35%~1.49%,其中,高丹草、苏丹草、狼尾草对土壤Cd的移除率分别达到1.46%、1.49%和1.48%;高丹草、苏丹草、狼尾草间作不仅可以有效降低空心菜Cd含量,同时对污染土壤中Cd具有较高的移除率,在Cd污染农田土壤的间作修复中具有较好的应用价值.     

Sulfur dioxide and o-xylene co-treatment in biofilter: Performance, bacterial populations and bioaerosols emissions

Sulfur dioxide(SO_2) and benzene homologs are frequently present in the off-gas during the process of sewage sludge drying. A laboratory scale biofilter was set up to co-treat SO_2 and o-xylene in the present study. SO_2 and o-xylene could be removed simultaneously in a single biofilter. Their concentration ratio in the inlet stream influenced the removal efficiencies. It is worth noting that the removal of SO_2 could be enhanced when low concentrations of o-xylene were introduced into the biofilter. Pseudomonas sp., Paenibacillus sp., and Bacillus sp. were the main functional bacteria groups in the biofilter. Sulfur-oxidizing bacteria(SOB) and o-xylene-degrading bacteria(XB) thrived in the biofilter and their counts as well as their growth rate increased with the increase in amount of SO_2 and o-xylene supplied. The microbial populations differed in counts and species due to the properties and components of the compounds being treated in the biofilter. The presence of mixed substrates enhanced the diversity of the microbial population. During the treatment process, bioaerosols including potentially pathogenic bacteria, e.g., Acinetobacter lwoffii and Aeromonas sp., were emitted from the biofilter. Further investigation is needed to focus on the potential hazards caused by the bioaerosols emitted from waste gas treatment bioreactors.     

炼油厂自流含油污水系统的安全风险及预防

系统分析了炼油厂自流含油污水系统设计、施工及运行管理方面存在的主要安全风险。针对性地提出了设计方面进行水封、管道合理设计及井盖合理选材,施工方面进行变形污水井整改、污水管道规范施工,运行管理方面做好系统密封、标识、检测并严控着火源、污水合格排放等预防措施,降低含油污水系统安全风险,确保安全运行。     

通用机场噪声影响预测评价问题及对策研究

中国通用航空已进入蓬勃发展的新时期,将不可避免地带来噪声影响问题。通过对目前通用机场噪声影响预测评价工作进行总结,发现通用机场噪声影响预测评价存在现有技术导则及规范的针对性不强,机场噪声评价标准的适用性不强,评价等级和范围确定的合理性不足,且缺乏对噪声预测源强进行实测验证,噪声防治措施研究及有效性论证不足等问题。由此提出积极制定适用性强的技术导则和评价标准,以期更好地指导通用机场噪声影响预测评价工作实践。     

网络系统最佳震灾对策研究：以古交市供水系统为例

以古交市供水管网系统为例,运用网络分析法分析现有网络系统的可靠性,并提出改进措施,为古交市的供水系统提供最佳震灾对策．     

水合二氧化锰界面特性及其除污染效能

研究了水合二氧化锰(δMnO2)的界面特性及其吸附性能.考察了δMnO2的比表面积、粒径分布、表面官能团及ζ电位;探讨了δMnO2对水中亚砷酸盐及腐殖酸的吸附去除效能.结果表明:δMnO2的比表面积为117.4m2·g-1,体积平均粒径为0.11μm;δMnO2表面具有丰富的表面羟基(Mn-OH);随着pH值由1.9升高至10.7,δMnO2的ζ电位由 22.7mV降低至53.5mV,其零电荷点在pH3.0附近.δMnO2对亚砷酸盐(As(III))及腐殖酸(HA)均表现出优良的吸附去除效能,其单位δMnO2质量的最大吸附量分别为137μgAs(III)·mg-1δMnO2和1.01mgTOC·mg-1δMnO2.亚砷酸盐与腐殖酸共存时,腐殖酸的存在使得亚砷酸盐的去除率下降10%—28%;而亚砷酸盐对腐殖酸的去除无明显影响.