Polychlorinated biphenyls (PCBs) and halogenated flame retardants (HFRs) in multi-matrices from an electronic waste (e-waste) recycling site in Northern China

The present study investigated the occurrence of polychlorinated biphenyls (PCBs) and halogenated flame retardants (HFRs) in soil, water, reed, air and dust samples collected from the e-waste recycling region in Ziya Town, Northern China. The results showed that the concentrations of PCBs reached relative high level in environmental matrices in the study area. HFRs including polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), allyl 2,4,6-tribromophenyl ether (ATE), tetrabromoethylcyclohexane (TBECH), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), 2,3-dibromopropyl 2,4,6-tribromophenyl ether (DPTE), 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE) and so on were also widely detected in multi-matrices. Long-range atmospheric transport (LRAT) potentials of non-BDE HFRs were assessed to address the LRAR abilities of these compounds. Analysis of soil–air exchange of PCBs and HFRs showed that soil acted as a secondary source to the atmosphere only for a few low molecular weight compounds, while the direction of the flux of most detected chemicals was from air to soil.     

Chemical oxidation of sulfadiazine by the Fenton process: Kinetics,pathways, toxicity evaluation

This paper investigated sulfadiazine oxidation by the Fenton process under various reaction conditions. The reaction conditions tested in the experiments included the initial pH value of reaction solutions, and the dosages of ferrous ions and hydrogen peroxide. Under the reaction conditions with pH 3, 0.25 mM of ferrous ion and 2 mM of hydrogen peroxide, a removal efficiency of nearly 100% was achieved for sulfadiazine. A series of intermediate products including 4-OH-sulfadiazine/or 5-OH-sulfadiazine, 2-aminopyrimidine, sulfanilamide, formic acid, and oxalic acid were identified. Based on these products, the possible oxidation pathway of sulfadiazine by Fenton's reagent was proposed. The toxicity evaluation of reaction solutions showed increased antimicrobial effects following the Fenton oxidation process. The results from this study suggest that the Fenton oxidation process could remove sulfadiazine, but also increase solution toxicity due to the presence of more toxic products.     

Effect of blue light on early sporophyte development of Saccharina japonica (Phaeophyta)

Growth and photosynthesis in the blade of Saccharina sporophytes are strongly stimulated by blue light. However, little is known about the effect of blue light on the early development and longitudinal photosynthesis profile of Saccharina sporophytes. In this study, S. japonica sporelings were cultured under blue or red light for 8 weeks. Blue light affected longitudinal, tangential cell divisions and tissue differentiation early in sporophyte development. The number of latitudinal cells in the blade under blue light was over fivefold that under red light. In addition, the number of cell layers was higher in the growing point than in the blade under blue light, whereas sporelings grown under red light contained only a single cell layer. Under blue light, the photosynthetic capacities of the growing region, blade and stipe were similar, and the maximum relative electron transport rate was even lower in the growing point than in the blade. The longitudinal photosynthesis profile suggested that blue light stimulated the enzymes participating in light-independent carbon fixation in the growing point and accordingly was less dependent on high light irradiances. Collectively, the results indicated that blue light promotes the early development of S. japonica sporophytes, which was attributed to both photomorphogenetic responses and photosynthetic reactions.     

燃气爆炸作用下房屋裂缝开展的分形模拟

烯气爆炸灾害下房屋裂纹开展有的模式与受均布压力破坏时的相同,在参照实验所得混凝土裂缝的分形维数资源的基础上编制了相应的软件,利用分形插值的方法实现裂缝开展的模拟,模拟结果较好地反映了裂缝发展的真实情况,且较以往的模拟方法节约了大量存储空间。     

Micropollutant removal and disinfection byproduct control by sequential peroxymonosulfate-UV treatment in water: A case study with sulfamethoxazole

UV/peroxymonosulfate (UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole (SMX) was selected as the target micropollutant. Four different operational approaches, including UV alone, PMS alone, simultaneous UV/PMS and sequential PMS-UV, were compared for their differences in SMX removal and disinfection by-product (DBP) formation potentials during chlorine-driven disinfection. Among the four approaches, UV/PMS and PMS-UV achieved over 90% removal efficiencies for SMX without substantial differences. For raw water, the trichloronitromethane (TCNM) formation potential after treatment with PMS-UV was lower than that after UV/PMS treatment. The time interval over which the PMS-UV process was conducted had little effect on the final removal efficiency for SMX. However, a brief (5 min) pre-PMS treatment significantly reduced the TCNM formation potential and the genotoxicity from DBPs. The formation risk for TCNM during chlorination increased markedly with increasing PMS dosages, and the appropriate dosage under these experimental conditions was suggested to be 0.5–1.0 mmol/L. Under alkaline conditions, PMS-UV treatment can enhance SMX degradation as well as dramatically reduced the formation potentials for haloketones, haloacetonitriles and halonitromethanes. This study suggests that proper optimization of UV/PMS processes can remove SMX and reduce its DBP formation.     

Reaction zone structures and propagation mechanisms of flames in stearic acid particle clouds

Reaction zone structures and propagation mechanisms of two representative flames established in stearic acid (CH₃(CH₂)₁₆CO₂H) particle clouds have been investigated. The reacting zone structure was examined by using a micro-electrostatic probe and a high-speed schlieren system. A distinct difference was observed in the ion current fluctuations recorded across the two representative flames propagating through the clouds of the same total mass density of particles and different mass densities of the particles smaller than 60 μm in diameter. When the mass density of smaller particles was high, a single peak was recorded in the ion current fluctuation. On the other hand, when the mass density of smaller particles was low, multi-peaks of various heights and widths were recorded. In the former case, the single peak was considered to be attributable to a unitary and a relatively thin flame started burning in vapor generated by the evaporation of smaller particles in the preheat zone. The flame propagation mechanism in this case was inferred to be similar to that of a usual hydrocarbon–air premixed flame, although the reaction zone thickness is much larger than that of the premixed flame. In the latter case, the multi peaks of various shapes were considered to be attributable to strong combustion at blue spots far behind the schlieren front. The flame propagation in this case was inferred to be supported by the heat release due to combustion at the blue spots.     

水源切换对水厂出水细菌群落的影响

针对水源切换可能造成水厂出水微生物风险的问题,以北京某水厂由本地水源切换为河北水源期间原水和出厂水为研究对象,采用焦磷酸测序技术对水中的微生物种群结构和潜在致病菌进行分析.结果显示,出厂水的细菌多样性显著低于原水,原水和出厂水中的优势菌均为变形菌门(Proteobacteria),所占比例为11.99%~95.48%,其中包括α,β和γ变形菌纲(α, β, γ-Proteobacteria),但相对丰度有较大差异.水源切换后的原水中优势菌为蓝藻门(Cyanobacteria),且该菌在切换后的出厂水中也存在.出厂水中检测到部分潜在致病菌,优势菌包括不动杆菌(Acinetobacter)和代尔夫特菌(Delftia),增加了饮用水的微生物安全风险.PCoA结果显示,水源切换前后原水中细菌群落结构变化较大,但改变水源对出厂水的微生物群落影响较小,水厂能够维持稳定的运行.     

压缩型国家人口问题的经济学根源探究

由予工业化发生的时间、背豢、速度的差异。发展中国家的经济、环境、人口问题呈现出与发达国家不同的特点．从人口学角度分析，具有以下几个特征：人口红利型经济期缩短、人口红利泡沫、人口红利期与实际抚养系数大的矛盾交织等。发展中国家具有的压缩性特征使人口与资源、环境的关系出现了新特征．其中分析人口与经济的关系对建设和谐社会、实现经济社会可持续发展起着十分重要的作用。研究认为引起发展中国家人口问题的经济学根源是：①现代化的产业结构的要求与劳动力现代科学素质普遍低下不相适应；②生产性消费的盲目跟进；③对西方理论的“非本土化”借用。创造“一百英镑技术”型经济模式是解决发展中国家人口问题．保持经济社会稳定持续发展的有效方法。     

我国碳排放权交易机制试点地区的ETS管理效率评价

以我国7个碳排放权交易机制试点地区的碳交易体系(ETS)和19个地区模拟ETS的设计方案、调研数据为基础,采用C2GS2模型作为基本工具构建数据包络分析模型(DEA)对碳交易机制的管理效率进行评价.结果显示,在7个试点地区中,北京、广东、深圳和重庆ETS机制的管理效率为DEA有效;上海和天津ETS处于规模递增阶段,湖北处于规模递减阶段,通过其在有效生产前沿面上的“投影”提出调整方案.建议:ETS覆盖的碳排放量低于地区总排放量的50%;下调中国核证自愿减排量(CCER)的碳抵消比例;紧紧围绕机制所覆盖的企业特征,进行投入要素规模设计;惩罚机制必不可少,但惩罚力度需根据本地区ETS投入要素特点进行设计;对ETS的碳排放上限(减排率)不宜设计过紧,否则可能对地区经济可持续发展能力造成损害.     

Historical change of heavy metals in urban soils of Nanjing, China during the past 20 centuries

Two typical areas, including once commercial and residential quarters of Nanjing, China, were studied by investigating soil properties especially heavy metals of soils in various cultural layers formed in different Chinese Dynasties. The age of the soil profiles was dated by both archaeological and 14C chronological methods. The results showed that urban soils in the old commercial/workshop quarter of Nanjing were generally contaminated by heavy metals Cu, Zn, Pb, but their concentration levels varied significantly among the cultural layers formed in different dynasties. The substantial increase of heavy metals appeared in three historical periods, i.e., South Dynasty (222-589 AD), the earlier Ming (1368-1644 AD) and the late Qing (1644-1912 AD) in one area. The tremendous input and storage of heavy metals in soils was explained by the primitive smelting and the strengthened metal processing activities, which might be due to the requirement of weapon making or other industries, in the changing social conditions of the corresponding periods. Soils in the once noble political, cultural centers did not show significant increase of heavy metals. The difference in the distribution pattern of heavy metals revealed the contrasting history of the site uses. The change of contaminant level in soils is believed to be a reflection of various human activities in the city during the past 20 centuries.