大气环境约束下的中国煤炭消费总量控制研究

煤炭消费过程中排放的大气污染物已成为我国大气污染的重要来源。本文采用WRF-CAMx 空气质量模型定量分析了煤炭消费- 污染物排放- 空气质量之间的影响关系,基于情景分析方法,研究了2020 年、2030年空气质量改善需求对地区大气污染物排放总量与煤炭消费总量的约束作用。在此基础上,结合重点地区行业发展与能源供需等因素,提出各省煤炭消费总量控制目标与控煤对策建议。研究结果表明,要实现2020 年、2030 年空气质量改善阶段性目标,全国煤炭消费总量应分别控制在40.8 亿吨和37.7 亿吨左右,京津冀鲁豫等11 个重点省份2020 年煤炭消费量应控制在15.8 亿吨、2030 年控制在13.1 亿吨,全国煤炭清洁化利用水平需要在当前基础上大幅度提升。     

Treatment of Sulfate/Sulfide-Containing Wastewaters Using a Microbial Fuel Cell: Single and Two-Anode Systems

The microbial fuel cell (MFC) was employed to convert reductive potential in sulfate-laden wastewaters to electricity via reducing sulfate to sulfide by sulfate-reducing bacteria and then oxidizing sulfide to sulfur by exoelectrogens. The excess sulfide presented in the anodic solution inhibited the activities of functional strains in MFC. This study proposed the use of a two-anode system, with a sulfate-reducing bacteria anode and an exoelectrogen (C27) anode in the anodic cell, to efficiently convert reductive potential of sulfate into electricity. The microbial community of sulfate-reducing bacteria anode and the electrochemical characteristics of the studied MFCs were reported.     

Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid

Understanding the effects of oxalic acid (OA) on the immobilization of Pb(II) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(II) by KH₂PO₄, phosphate rock (PR), activated phosphate rock (APR) and synthetic hydroxyapatite (HAP) at different phosphate:Pb (P:Pb) molar ratios (0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or CaCl₂, Community Bureau of Reference (BCR) sequential extraction and toxicity characteristic leaching procedure (TCLP) methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after 120 days was reduced by 100% when soils were amended with APR, HAP and HAP + OA, and the TCLP-Pb was < 5 mg/L for the red soil at P:Pb molar ratio 4.0.Water-soluble Pb could not be detected and the TCLP-Pb was < 5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APRwasmost effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pbmolar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.     

Spatial heterogeneity of lake eutrophication caused by physiogeographic conditions: An analysis of 143 lakes in China

In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, including three very different types of topography, i.e., the first topography ladder(FTL), second topography ladder(STL), and third topography ladder(TTL), were statistically analyzed. Lakes in the FTL and STL, located at high elevation(above1000 m) and low longitudes(lower than 105° E), were sporadically oligotrophic, whereas lakes in the TTL were almost all mesotrophic and eutrophic. The trophic level index(TLI)became higher with the rise of longitude. Two turning points(5 and 15°C) on the curve of TLI as function of the average annual temperature(AAT) corresponded with the AAT in different lake regions in the STL and TTL. Because the responses of TLI to AAT differ significantly, there were variations of nutrient and algal biomass concentrations in different lake regions in the same type of topography ladder. According to the differences in utilization efficiency of total nitrogen or total phosphorus by phytoplankton, China could be partitioned into six lake regions. Scientific nutrient criteria for each lake region shall be established considering these differences in China.     

基于MODIS的湖南省农业干旱监测模型

诸多遥感干旱监测指数已被成功应用于中国北方地区,但在南方湿润地区的应用则相对较少。以湖南省为研究区,结合遥感(RS)、地理信息系统(GIS)技术,利用MODIS增强植被状态指数(EVCI)和温度状态指数(TCI)的复合信息,并根据EVCI和TCI对干旱信息的敏感程度不同,赋予不同的权重值,建立干旱状态指数(DCI)遥感监测模型,并将该模型应用于湖南省农作物的旱情监测,得到了湖南省耕地旱情等级的空间分布图。通过与该省97个气象台站同期获取的综合气象干旱指数(CI)的相关分析与验证,表明DCI与CI指数的线性相关显著,EVCI和TCI的权重分别取值0.4和0.6时为最佳组合,并论证了该模型适宜南方地区的干旱监测。     

基于孔板和文丘里管复合结构空化器的空化效果数值模拟

基于计算软件Fluent,选用在低压区引入空化模型中的混合多相流模型,针对孔板和文丘里管复合空化发生器中孔板在文丘里管喉部前部、中间、后部3种结构对水力空化效果的影响进行了数值模拟计算,获得了汽含率、湍动能以及流线速度矢量分布图等数据。结果表明:文丘里管喉部夹载孔板后空化效果显著提高,而且在文丘里管后部流域中发生了二次空化;空化现象大部分发生在孔板小孔和文丘里管后部,且最高汽含率区域发生在孔板末端区域;多孔孔板置于文丘里管喉部后部时空化效果更加明显。     

Food additives for the synthesis of metal nanoparticles: a review

Environmental Chemistry Letters - Metal nanoparticles have found applications in many fields such as molecular diagnostics, electronic devices and environmental remediation. Nonetheless,...     

Factors affecting the distribution of microplastics in soils of China

● Microplastic (MP) abundance in soil of China was highly heterogeneous. ● MP abundance was higher near large rivers and central land affected by monsoons. ● MP abundance was correlated with longitude, mulching film, and average temperature. ● Factors suitable for predicting MP pollution using models were discussed. Microplastics (MPs) are found worldwide in high abundance, posing a potential threat to ecosystems. Despite the ubiquity of MPs in the environment, very little is known about the regional distribution of MPs and underlying factors affecting this distribution in the field, which likely include human activity, but also features of the environment itself. Here, out of a total of 1157 datapoints investigated in 53 Chinese studies, 9.68% datapoints were removed as outliers in the heterogeneity analysis. This review revealed that the abundance of MPs was highly heterogeneous. In addition, microplastic (MP) distribution maps based on China demonstrated that the highest abundance of MPs tended to occur near large rivers and central land affected by the intersection of two monsoons. The model-fitting and previous studies showed that MP abundance in China was correlated with longitude, agricultural mulching film usage per capita, temperature, and precipitation. However, due to the heterogeneity of MPs and the low matching degree between the current environmental data and the sampling points, this pattern was not as evident as reported in any single study. Factors affecting the distribution of MPs can not be captured by linear relationships alone, and systematic selection of suitable environmental factors and further model optimization are needed to explore the cause of MP pollution in soil. Overall, this review revealed an uneven distribution of MPs and serves as a reference for model prediction to assess and control plastic pollution in natural soil environments.     

京津唐地区地震灾害区域宏观脆弱性变化研究

研究灾害脆弱性的变化有助于深入理解灾害及灾害风险的形成机制。在重新审视承灾体系统灾害脆弱性的分析层次和描述角度之后,深化了对地震灾害区域宏观脆弱性的影响因素和描述指标的再认识,完善了以主成分分析为核心技术的分析该类脆弱性时空变化的数理方法。以此为基础,以1985、1995、2000和2004年为代表时期,对京津唐地区20多年来的地震灾害区域宏观脆弱性的变化做了进一步的分析和总结。主要结论是:研究区地震灾害区域宏观脆弱性20多年来的时空变化可分解为少数几种脆弱性模式的变化;1985年以来,该类脆弱性的空间分异格局整体稳定;但是,各地自身脆弱与否的程度20多年来的变化却很显著——各大中城市市区的脆弱程度显著增强,其他地区整体减弱,且变化幅度前者显著大于后者;研究区地震灾害区域宏观脆弱性的时空变化主要受该地区的人口和经济特别是工商业经济的增长、城市化发展和产业结构的调整等3方面因素所驱动。     

Impact of alkyl methacrylate–maleic anhydride–alkyl methacrylate terpolymers as cold flow improver on crystallization behavior of diesel fuel

Alkyl methacrylate–maleic anhydride–alkyl methacrylate terpolymers (MR₁–MA–MR₂) is one of the widely used cold flow improver. In order to develop more efficient MR₁–MA–MR₂, it is necessary to study the crystallization behavior of n-alkanes when adding MR₁–MA–MR₂ into diesel fuel. In this paper, MR₁–MA–MR₂ is prepared by the reaction of long-chain alkyl methacrylate (MR₁), maleic anhydride (MA), and short alkyl methacrylate (MR₂). The diesel fuel before and after adding MR₁–MA–MR₂ is in situ filtrated at its cold filter plugging point (CFPP) in a manual CFPP apparatus. Extensive measurements of composition variation of n-alkanes are done by gas chromatograph and the results are compared. The experimental results show that after adding MR₁–MA–MR₂, the concentration distribution of n-alkanes in the filtrate is wide and arranges from 8 to 26, and mainly centralizes from 10 to 19. For the precipitate, the concentration distribution of n-alkanes gets richer in the lighter n-alkanes and poorer in the heavier n-alkanes. The concentration distribution of n-alkanes in the crystal solid shows a decreasing trend, especially with high carbon number n-alkanes (heavier than C₂₀). About 60–70% of the residual crystal solid is composed of non-paraffins such as isoparaffin, naphthene and other components. Crystallinities of n-alkanes show a slow decrease trend from C₈ to C₂₀. When the carbon number n-alkanes are heavier than C₂₀, the crystallinities of n-alkanes begin to sharply reduce with an increase of carbon number. The largest decline of crystallinity is C₂₆ n-alkane from 38.39% to 7.90%.