京津冀“以电代煤”替代大气污染物排放清单

本研究建立了基于人工神经网络的民用散煤燃用量估算模型,得到了京津冀地区“以电代煤”替代民用散煤大气污染物排放清单.结果表明：截止到2018年,京津冀地区“以电代煤”替代散煤用户约259万户,每年可减少散煤燃烧约706.6万t,减少PM_2.5、NO_x、SO₂的排放量分别约为2.81,0.76,2.17万t.其中,北京市和天津市实施效果较为明显,占京津冀地区“以电代煤”散煤替代总量的62.01%和22.82%.基于调研数据得到京津冀各市燃煤量月分布系数,1月份分布系数最大,燃煤量占比为27%~40%.     

Influence of particle size on the aggregation behavior of nanoparticles: Role of structural hydration layer

More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and pH all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.     

高温高湿巷道内不稳定换热系数影响因素分析及模型建立*

为研究高温高湿巷道不稳定换热系数的变化规律,采用Fluent软件对高温高湿巷道内的热湿交换进行数值模拟,通过单因素和正交模拟实验探讨风流温度、风流速度、岩石导热系数、原岩温度以及巷道当量直径对高温高湿巷道不稳定换热系数的影响。研究结果表明:高温高湿巷道不稳定换热系数随时间的变化规律与普通巷道一致,均与通风时间呈负相关,但通风时间为1 a的高温高湿巷道不稳定换热系数较普通巷道增加了12.5%。通过单因素分析得到风流速度、岩石导热系数和当量直径与不稳定换热系数呈正相关。通过极差分析得到各因素对不稳定换热系数的影响程度为:岩石导热系数>当量直径>风流速度>风流温度>原岩温度。利用SPSS软件对正交实验数据进行拟合,建立不稳定换热系数的计算模型,拟为高温高湿巷道内热负荷计算及井下风温预测提供参考。     

粉煤灰对垃圾填埋场黄土垫层的改性试验

通过击实、渗透试验得到粉煤灰改性-黄土的最佳配比为10%。对压实黄土和压实粉煤灰改性-黄土,分别用清水和渗滤液进行室内渗透试验,结果表明:渗滤液在压实粉煤灰改性黄土中的渗透系数≤1.0×10-7cm/s,在压实黄土中的渗透系数≤1.0×10-5cm/s,前者可作为填埋场防渗垫层,后者可作为填埋场防渗保护垫层。对COD、NH3-N的去除效果前者优于后者。     

大气封闭型扩散浓度估算模式细探

从大气封闭型扩散实际反射路径分析入手,引入上下边界不同的反射率与污染物衰减系数,得出比以往公式更具一般意义的大气封闭型扩散的污染物浓度估算公式,特别适用于边界具有一定吸收能力与污染物质有衰减的情况,从而有效改进污染贡献的估算精度.文中展示的示意图,纠正了以往示意图的错误.      

Assessment of soil and soil-gas radon activity using active and passive detecting methods in Korea

Radon ((222)Rn) is a carcinogenic gas produced by the radioactive decay of radium ((226)Ra). It has been reported that soil and soil-gas are primary factors that could cause indoor radon problems. Six sites were selected for this study--Sanbook, Gangcheon, Jikyeong, Choojung, Geumsung and Homyoung--each was classified according to bedrock type. In order to investigate soil-gas radon activities and radon emanating power, innovated active and passive detecting methods were developed and applied under both field and laboratory conditions. Statistical analysis of results confirmed that the radon activity values measured using either active or passive methods under field or laboratory conditions could be interchangeable with each other.     

甘肃省城镇不同收入水平群体家庭生态足迹计算

生态足迹是测度环境可持续发展的新方法。家庭生态足迹H(ousehold EcologicalFootprint,H EF)是利用生态足迹方法研究家庭消费所产生的环境影响。通过计算不同收入水平群体的家庭生态足迹,比较不同收入水平群体H EF差异,可以进一步揭示各收入水平群体间存在的“生态足迹掠夺”和生态足迹占用公平性。在阐述家庭生态足迹内涵意义及计算方法的基础上,以甘肃省2002年城镇不同收入水平群体为例进行实证研究。通过计算得到甘肃省2002年不同收入群体的家庭生态足迹分别为:最高收入群1.412×106ghm₂,高收入群1.131×106ghm₂,较高收入群1.860×106ghm₂,中等收入1.793×106ghm₂,较低收入群1.536×106ghm₂,低收入群0.724×106ghm₂,最低收入群0.578×106ghm₂,全省平均1.265×106ghm₂;分析经济收入与家庭生态足迹的关系表明,每增加1000元人均可支配收入,将增大0.2ghm₂家庭生态足迹;引入生态足迹掠夺及总生态足迹掠夺,并进一步计算生态足迹不公平系数为0.24,表明收入不同引起的足迹消费的不公平不突出。     

钐染毒对小鼠脏器系数和睾丸酶活性的影响

为了研究稀土元素钐对雄性小鼠脏器系数和睾丸内酶活性的影响,将小鼠分组分别自由饮用含硝酸钐0,4,20,100,500mg/L的水,3个月后处死小鼠,称量体重和主要脏器重量,并测定睾丸内乳酸脱氢酶(LDH)、酸性磷酸酶(ACP)、碱性磷酸酶(ALP)和三磷酸腺苷酶(ATP酶)活力.结果表明,20,100mg/L剂量组小鼠附睾脏器系数明显低于对照组;100,500mg/L剂量组LDH酶活力明显受到抑制,且染毒剂量与LDH酶活力呈剂量-反应关系;各处理组ALP酶活力明显升高,而ACP酶活力不受影响;3种ATP酶活力都随钐浓度的增加有“低促高抑”的趋势.钐亚慢性染毒对小鼠生殖性腺具有一定的毒性作用,其中LDH和ALP可作为稀土元素钐作用于睾丸的标志酶.     

三油酸甘油酯-醋酸纤维素复合膜萃取水体中痕量有机氯农药的研究

以三油酸甘油酯-醋酸纤维素复合膜(TECAM)萃取作为监测水体中痕量有机氯农药的方法．探讨分析过程中的影响因素和优化条件,结果表明,膜萃取分析方法对17种有机氯农药的平均加标回收率为53％-111％,对强疏水性污染物表现出较高的回收率．利用该方法在南方某自来水厂各工艺段水体中检测出了滴滴涕及其代谢产物、六六六等五种有机氯农药．     

Mechanism of calcium mitigating membrane fouling in submerged membrane bioreactors

Two parallel membrane bioreactors (MBRs) were operated under different calcium dosages (168.5, 27 mg/L) to gain a better understanding of the mechanism of retarding membrane fouling by adding calcium. The results showed that the particle size of sludge flocs increased and the particle size distribution tended to be narrow at the optimum dosage (168.5 mg/L). Calcium was effective in decreasing loosely bound extracellular polymeric substances (LB-EPS) in microbial flocs and soluble microbial products (SMP) in the supernatant at the dosage of 168.5 mg/L by strengthening the neutralization and bridging of EPS with flocs. Furthermore, the amount of COD_S and COD_C decreased in both the mixed liquor and the fouling cake layer on the membrane surface. In order to compare the filtration characteristics of cake layers from the MBRs with the two calcium dosages, the specific cake resistance and the compressibility coefficient were measured. The specific cake resistance from the MBR with optimum dosage (168.5 mg/L) was distinctly lower than that with low dosage (27 mg/L). The compressibility coefficient of the cake layers under two dosages were respectively attained as 0.65, 0.91. Scanning electron microscopy (SEM) and three-dimensional confocal scanning laser microscope analysis (CLSM) images were utilized to observe the gel layer directly.