1951~2014年中国北方地区气温突变与变暖停滞的时空变异性

基于1951~2014年中国北方及周边地区357个气象站点平均最低气温、平均气温和平均最高气温年（月）数据,采用M~K检验等方法,分析了中国北方地区3类气温突变和变暖停滞特征的时空变异性.结果表明：研究区3类气温整体突变年（1978~1999年、1981~2002年、1981~2005年）、分布广泛的普遍突变年（1988年、1989年、1997年）及范围（3a）均依次变晚.整体上,突变年随纬度降低变晚,东北突变早于西北和华北地区.变暖停滞集中于1998和2007年及其前后,3类气温亦依次变晚（1994~2007年、1995~2009年、1998~2010年）,由黄河流域中段向其他方向越来越晚.突变至变暖停滞周期整体随纬度降低缩短（3~30a）,突变越早周期越长.西北地区突变与变暖停滞前后各时段均值温差最大（2.4℃）,温差在1℃左右站点分布最广泛.各时段升（降）温速率整体依次在0.01℃/10a、0.05℃/10a、-0.03℃/10a左右站点分布最广泛,突变后升温最快（0.02~0.16℃/10a）,且西北地区对升温贡献最大,变暖停滞后东北地区对降温贡献最大,2时段按平均最低气温、平均最高气温、平均气温顺序升（降）温速率递减.3类气温波动程度减弱,整体随纬度降低.高纬度、高海拔和山地地区突变和变暖停滞较周边地区偏早或偏晚,特征值较大.整个北方地区3类气温突变、变暖停滞、突变与变暖停滞时间及各时段特征值各自具有自身一致性的普遍规律.     

海域高温油田1株耐高温耐盐硫酸盐还原菌的筛选与生理特性及活性抑制

油田中硫酸盐还原菌(SRP)的生长代谢能产生大量H_2S,会引起油藏酸化和微生物腐蚀等严重的生产和环境问题,而关于油田环境中SRP微生物多样性与生理活性的研究仍十分缺乏.为了深入了解我国渤海湾海域高温酸化油藏中SRP代谢特点并探究其潜在危害控制方法,本研究采用厌氧纯培养技术从渤海湾某高温油田采出水中分离筛选到1株耐高温、耐盐的SRP菌株BQ1,研究了其生理特性,并评价了不同杀菌剂和代谢抑制剂对其产H_2S活性的影响.结果表明,菌株BQ1的细胞呈短杆状,大小为(1.2~2.5)μm×(0.5~0.8)μm,有运动性.尽管BQ1与普通脱硫弧菌(Desulfovibrio vulgaris Hildenborough)的16S rRNA基因序列相似性达99%,但两者生理特性具有明显差异.BQ1可在温度为14~70℃(最适30℃)、p H 6.0~9.0(最适7.0)、盐度为0%~10%条件下生长代谢.BQ1可利用甲酸钠、乳酸钠、乙酸盐等多种碳源,能以硫酸盐、亚硫酸盐、硫代硫酸盐或单质硫为唯一电子受体产生H_2S.次氯酸钠(600 mg·L~(-1))、苄基三甲基氯化铵(300 mg·L~(-1))或NaNO_3(800 mg·L~(-1))对BQ1产H_2S活性无明显抑制效果.戊二醛(50 mg·L~(-1))、溴硝醇(30 mg·L~(-1))、二氧化氯(50 mg·L~(-1))或NaNO_2(70 mg·L~(-1))可抑制BQ1产H_2S活性达30 d以上,是控制渤海湾高温油田微生物酸化的潜在有效抑制剂.     

Phytotoxicity and groundwater impacts of leaching from thermal treatment residues in roadways

The use of coal fly ash (CFA), municipal solid waste incinerator bottom ash (MSWIBA) and flue gas desulfurization residue (FGDR) in road construction has become very common owing to its economical advantages. However, these residues may contain toxic constituents that pose an environmental risk if they leach out and flow through the soil, surface water and groundwater. Therefore, it is necessary to assess the ecotoxicity and groundwater impact of these residues before decisions can be made regarding their utilization for road construction. In this study, the physico-chemical characteristics, leaching and phytotoxicity of these residues were investigated. Specifically, multivariate analyses were used to evaluate the contributions of the leaching constituents of the CFA, MSWIBA and FGDR leachates to the germination index of wheat seeds. B, Ba, Cr, Cu, Fe and Pb were found to be more toxic to the wheat seeds than the other heavy metals. Furthermore, the leached concentrations of the constituents from the CFA, MSWIBA and FGDR were below the regulatory threshold limits of the Chinese identification standard for hazardous wastes. Analyses conducted using a numerical groundwater model (WiscLEACH) indicated that the predicted field concentrations of metals from the CFA, MSWIBA and FGDR increased with time up to about 30 years at the point of compliance, then decreased with time and distance. Overall, this study demonstrated that the risks resulting from MSWIBA, CFA and FGDR leaching could be assessed before its utilization for road construction, providing crucial information for the adoption of these alternative materials.     

Insights into sludge granulation during anaerobic treatment of high-strength leachate via a full-scale IC reactor with external circulation system

In this study, a full-scale internal circulation(IC) reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste(MSW)incineration plant, in which anaerobic sludge granulation was intensively investigated. Results showed that the IC reactor achieved excellent treatment performance under high organic loading rates(OLR) of 21.06–25.16 kg chemical oxygen demand(COD)/(m3? day). The COD removal efficiency and biogas yield respectively reached 89.4%–93.4% and 0.42–0.50 m3/kg COD.The formation of extracellular polymeric substances(EPS) was closely associated with sludge granulation. Protein was the dominant component in sludge EPS, and its content was remarkably increased from 21.6 to 99.7 mg/g Volatile Suspended Solid(VSS) during the reactor operation. The sludge Zeta potential and hydrophobicity positively correlated with the protein/polysaccharide ratio in EPS, and they were respectively increased from-26.2 m V and 30.35% to-10.6 m V and 78.67%, which was beneficial to microbial aggregation. Three-dimensional fluorescence spectroscopy(3 D-EEM) and Fourier transform infrared spectroscopy(FT-IR)analysis further indicated the importance of protein-like EPS substances in the sludge granulation. Moreover, it was also found that the secondary structures of EPS proteins varied during the reactor operation.     

Characteristics of molecular weight distribution of dissolved organic matter in bromide-containing water and disinfection by-product formation properties during treatment processes

The characteristics of dissolved organic matter (DOM) and bromide ion concentration have a significant influence on the formation of disinfection by-products (DBPs). In order to identify the main DBP precursors, DOM was divided into five fractions based on molecular weight (MW), trihalomethane formation potential and haloacetic acid formation potential were determined for fractions, and the change in contents of different fractions and total DBPs during treatment processes (pre-chlorination, coagulation, sand filtration, disinfection) were studied. Moreover, the relationship between bromide concentration and DBP generation characteristics in processes was also analyzed. The results showed that the main DBP precursors were the fraction with MW < 1 kDa and fraction with MW 3−10 kDa, and the DBP''s generation ability of lower molecular weight DOM (< 10 kDa) was higher than that of higher molecular weight DOM. During different processes, pre-chlorination and disinfection had limited effect on removing organics but could alter the MW distribution, and coagulation and filtration could effectively remove organics with higher MW. For DBPs, trihalomethanes (THMs) were mainly generated in pre-chlorination and disinfection, while haloacetic acids (HAAs) were mostly generated during pre-chlorination; coagulation and sand filtration had little effect on THMs but resulted in a slight removal of HAAs. In addition, the results of ANOVA tests suggested that molecular sizes and treatment processes have significant influence on DBP formation. With increasing bromide concentration, the brominated DBPs significantly increased, but the bromine incorporation factor in the processes was basically consistent at each concentration.     

Soot reduction by addition of dimethyl carbonate in normal and inverse ethylene diffusion flames: Nanostructural evidence

Oxygenated fuel represents an attractive alternative as an additive for reducing soot emissions.Dimethyl carbonate(DMC) is an oxygenated compound which is a good option to reduce soot,but the detailed characteristics of soot produced from combustion of hydrocarbon fuels blended with DMC are still lacking. The present research studied the nanostructure and reactivity of soot particles in ethylene/DMC normal and inverse diffusion flames. High resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), and thermogravimetric analysis(TGA)were used to analyze the nanostructure and reactivity of soot. It was found that DMC addition was effective in decreasing the average weights of soot formed in flames. The results of HRTEM images showed that soot particles obtained with DMC addition showed liquid-like material and tight bonding, and exhibited more highly disorganized layers, which give it higher reactivity than soot obtained without DMC addition. Furthermore, HRTEM was used to analyze soot fringe characteristics consisting of fringe tortuosity, fringe length, and fringe separation. XRD was used to crosscheck the results for fringe separation, and was consistent with HRTEM results. In addition, the mass loss curve of TGA experiments showed that DMC addition could enhance the reactivity of soot particles.     

A comparison of chemical MSW compositional data between China and Denmark

Chemical waste compositions are important for municipal solid waste management, as they determine the pollution potentials from different waste strategies. A representative dataset for chemical characteristics of individual waste fractions is frequently required to assess chemical waste composition, but it is usually reported in developed countries and not in developing countries. In this study, a dataset for Chinese waste was established through careful data screening and assessment, named as CN dataset. Meanwhile, a dataset for Danish waste (DK dataset) was also summarized based on previous studies. In order to quantitatively evaluate the reliabilities of CN and DK datasets, the chemical waste compositions in four Chinese cities were estimated by utilizing both of them, respectively. It is indicated that the usage of CN datasets led to significantly lower discrepancies from the actual values based on laboratory analysis in most cases. Within the datasets, the moisture contents of food waste, paper, textiles, and plastics, the carbon content of food waste, as well as the oxygen content of plastics would induce significant divergences, which should be paid special attention when gathering the information. In addition, the fractional waste compositions in China showed similar features with other developing countries but differ significantly with developed countries. Thus the above-mentioned conclusions could also be true in other developing countries.     

A comprehensive classification method for VOC emission sources to tackle air pollution based on VOC species reactivity and emission amounts

In China, volatile organic compound(VOC) control directives have been continuously released and implemented for important sources and regions to tackle air pollution. The corresponding control requirements were based on VOC emission amounts(EA), but never considered the significant differentiation of VOC species in terms of atmospheric chemical reactivity. This will adversely influence the effect of VOC reduction on air quality improvement. Therefore,this study attempted to develop a comprehensive classification method for typical VOC sources in the Beijing–Tianjin–Hebei region(BTH), by combining the VOC emission amounts with the chemical reactivities of VOC species. Firstly, we obtained the VOC chemical profiles by measuring 5 key sources in the BTH region and referencing another 10 key sources, and estimated the ozone formation potential(OFP) per ton VOC emission for these sources by using the maximum incremental reactivity(MIR) index as the characteristic of source reactivity(SR). Then, we applied the data normalization method to respectively convert EA and SR to normalized EA(NEA) and normalized SR(NSR) for various sources in the BTH region.Finally, the control index(CI) was calculated, and these sources were further classified into four grades based on the normalized CI(NCI). The study results showed that in the BTH region,furniture coating, automobile coating, and road vehicles are characterized by high NCI and need to be given more attention; however, the petro-chemical industry, which was designated as an important control source by air quality managers, has a lower NCI.     

粉煤灰提铝中间产物合成4A分子筛对氨氮的吸附行为研究

采用粉煤灰提铝中间产物合成4A分子筛,利用XRD、SEM、热重分析、化学成分分析、阳离子交换容量对4A分子筛进行表征.考察吸附时间、pH、分子筛投加量、氨氮初始浓度、共存阳离子对其吸附性能的影响,研究其对模拟废水中氨氮的吸附效果,并结合准二级动力学方程、吸附等温线研究吸附性能和机理.结果表明,初始浓度为50 mg·L~(-1)、4A分子筛投加量为5 g·L~(-1)、pH值为6~9、吸附时间为80 min时氨氮去除率可达71.34%;随着氨氮初始浓度升高,其去除率降低,吸附容量增加;共存阳离子Na~+、K~+、Ca~(2+)对NH_4~+有强烈的竞争吸附,Mg~(2+)无明显竞争作用.吸附过程符合准二级动力学方程和Freundlich模型.Langmuir吸附等温线显示最大吸附容量为20 mg·g~(-1).