How aerosol direct effects influence the source contributions to PM2.5 concentrations over Southern Hebei,China in severe winter haze episodes

The aerosol direct effects result in a 3%–9% increase in PM_2.5 concentrations over Southern Hebei. These impacts are substantially different under different PM_2.5 loadings. Industrial and domestic contributions will be underestimated if ignoring the feedbacks. Beijing-Tianjin-Hebei area is the most air polluted region in China and the three neighborhood southern Hebei cities, Shijiazhuang, Xingtai, and Handan, are listed in the top ten polluted cities with severe PM_2.5 pollution. The objective of this paper is to evaluate the impacts of aerosol direct effects on air quality over the southern Hebei cities, as well as the impacts when considering those effects on source apportionment using three dimensional air quality models. The WRF/Chem model was applied over the East Asia and northern China at 36 and 12 km horizontal grid resolutions, respectively, for the period of January 2013, with two sets of simulations with or without aerosol-meteorology feedbacks. The source contributions of power plants, industrial, domestic, transportation, and agriculture are evaluated using the Brute-Force Method (BFM) under the two simulation configurations. Our results indicate that, although the increases in PM_2.5 concentrations due to those effects over the three southern Hebei cities are only 3%–9% on montly average, they are much more significant under high PM_2.5 loadings (~50 μg·m⁻³ when PM_2.5 concentrations are higher than 400 μg m⁻³). When considering the aerosol feedbacks, the contributions of industrial and domestic sources assessed using the BFM will obviously increase (e.g., from 30%–34% to 32%–37% for industrial), especially under high PM_2.5 loadings (e.g., from 36%–44% to 43%–47% for domestic when PM_2.5>400 μg·m⁻³). Our results imply that the aerosol direct effects should not be ignored during severe pollution episodes, especially in short-term source apportionment using the BFM.     

冻土蠕变特性研究现状及展望

对目前冻土蠕变试验研究和模型研究的研究成果进行了总结。从微观蠕变试验和宏观蠕变试验两方面对冻土蠕变的试验研究进行介绍。分经验模型、流变模型和一般的应力-应变-时间模型对冻土蠕变本构模型研究进行分析总结。从试验研究和本构模型研究两方面介绍冻土的动蠕变研究进展。同时,也介绍了冻土与桩基之间冻结强度的研究。目前,冻土蠕变研究大都集中在短期冻结强度,尤其缺乏桩土之间蠕变变形及长期强度的相关研究。随着未来冻土区铁路、公路建设以及民用建筑等级的提高,桩基础将越来越多的被应用。为优化冻土区桩基的设计,在当前有必要加强冻土区桩基蠕变特性的研究。     

Preparation and assay of C-glucosyltransferase from roots of Pueraria lobata

C-glucosyltransferase (EC 2.4.1.X) is one of the key enzymes for the biosynthesis of puerarin. This paper describes the methodology in purification and assay of the enzyme for the first time in Puerarin lobata (Wild.) Ohwi. C-glucosyltransferase from roots of P. lobata was extracted and partially purified by (NH4)2SO4 saturation. The effects of pH, temperature, and substrate concentration on the activity of the enzyme were investigated. The properties of the puerarin produced by C-glucosyltransferase were studied by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The peak activity of C-glucosyltransferase was detected in fraction of by 80% saturation of (NH4)2SO4 and the optimal conditions for enzymatic reaction were 35.5 micromol l(-1) of isoliquiritigenin and 560 micromol l(-1) of UDP-G at pH 8.1, 28 degrees C for 1 h. Mn2+ at 1 mmol l(-1) and Al3+ at 1 mmol l(-1) increased the enzyme activity, while Mg2+ inhibited its activity. The enzyme activity in Nicotiana tabacum and P. lobata were detected under the above assay conditions. Higher activity was found in roots than in leaves and stems of P. lobata, while no enzyme activity was detected in leaves of N. tabacum. It was the first time that activity of C-glucosyltransferase, which transforms isoliquiritigenin to puerarin, was detected in P. lobata.     

栗钙土不同土地利用方式下土壤活性碳酸钙

土壤活性碳酸钙是指土壤中不稳定的、处于自由态、易发生化学反应的那部分碳酸钙。研究用KMnO4滴定法测定了内蒙古栗钙土的活性碳酸钙质量分数,目的是分析土地利用方式对土壤活性碳酸钙的影响。结果表明：201个土壤样品中活性碳酸钙质量分数的均值为20.57g·kg-1,变幅为0.63～135.59g·kg-1;不同土地利用方式下土壤活性碳酸钙质量分数的大小顺序为：退耕地锡林草地乌盟草地耕地;不同土地利用方式下土壤活性碳酸钙质量分数与碳酸钙质量分数均呈现极显著正相关关系;退耕地、乌盟草地、锡林草地的土壤活性碳酸钙质量分数分别与pH以及土壤粘粒质量分数呈现极显著正相关关系,而耕地的则未达到显著性水平,说明土地利用方式影响了土壤中碳酸钙的活性。土壤总碳酸钙质量分数（n=201）、pH（n=198）和粘粒质量分数（n=191）分别可以解释活性碳酸钙73%、13%和27%的变异。碳酸钙活度指数（CAI）包括了碳酸钙质量分数、pH和粘粒质量分数（CAI=pH＋0.01wCaCO3＋0.11wClay）,是基于每个变量对活性碳酸钙的相对影响而构建的,可以解释活性碳酸钙36%的变异（n=191）。     

PSM审核加强美企整束安全管理

在过去的20多年里,美国职业安全与健康管理局（OSHA）出台了很多旨在保护工厂工人安全的法规,工艺安全管理（PSM）规范即是其中之一。该规范要求对有毒、反应性、     

Microbial detoxification of metalaxyl in aquatic system

Four microorganisms, Pseudomonas sp. （ER2）, Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, were isolated from cucumber leaves previously treated with metalaxyl using enrichment technique. These isolates were evaluated for detoxification of metalaxyl at the recommended dose level in aquatic system. The effect of pH and temperature on the growth ability of the tested isolates was also investigated by measuring the intracellular protein and mycelia dry weight for bacterial and fungal isolates, respectively. Moreover, the toxicity of metalaxyl after 28 d of treatment with the tested isolates was evaluated to confirm the complete removal of any toxic materials （metalaxyl and its metabolites）. The results showed that the optimum degree pH for the growth of metalaxyl degrading isolates （bacterial and fungal isolates） was 7. The temperature 30℃ appeared to be the optimum degree for the growth of either fungal or bacterial isolates. The results showed that Pseudomonas sp. （ER2） was the most effective isolate in metalaxyl degradation followed by Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, respectively. There is no toxicity of metalaxyl detected in the supematant after 28 d of treatment with Pseudomonas sp. （ER2）. The results suggest that bioremediation by Pseudomonas sp. （ER2） isolate was considered to be effective method for detoxification of metalaxyl in aqueous media.     

Degradation and mineralization of 2-chloro-, 3-chloro- and 4-chlorobiphenyl by a newly characterized natural bacterial strain isolated from an electrical transformer fluid-contaminated soil

A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis was isolated from a soil contaminated with electrical transformer ?uid for over sixty years using Aroclor 1221 as an enrichment substrate. The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4'- and 4,4'-dichlorobiphenyl as well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustaine...     

如何评估国家层次上的生活满意度

概述 人们应该如何评估国家和个人的福利,即"幸福水平"呢?关于这个问题的答案对于国家甚至国际发展政策的制定至关重要,因为这些政策都清楚地将"变得更好"作为目标.勿庸置疑,如何衡量"更好"就成为了一个关键问题.     

Occurrence and distribution of organochlorine pesticides - lindane, p,p'-DDT, and heptachlor epoxide - in surface water of China

Persistent organochlorine pesticides pollutants (OCPs) have been reported to occur at relatively high concentrations in some Chinese waters. In order to map the distribution of organochlorine pesticides in the surface water throughout China, samples were collected from over 600 sites in seven major river basins and three main internal rivers drainage areas during 2003 and 2004. The surface water samples were analyzed for the representative organochlorine pesticides contaminants including lindane (gamma-HCH), p,p'-DDT and heptachlor epoxide. In general, the most frequently detected compound was lindane, being detected in 83.9% of samples (mean=31.3 ng/l; range <0.17-860 ng/l), and the highest concentration was present in the Yellow River basin. p,p'-DDT was detected in 63.1% of the samples collected (mean=14.6 ng/l; range <0.14-368 ng/l) with the highest concentration present in the Huaihe River basin. Heptachlor epoxide was detected in only 9.3% of water samples (range <0.11-10 ng/l). Measured concentrations for the three compounds were low and rarely exceed the environment quality standard for surface water of China. Lindane was more frequently detected at much higher concentrations in the rivers of northern China compared with those of southern China. The sites with higher concentration of lindane and p,p'-DDT mainly occurred in the Yellow River and Huaihe River basins, so the results of this investigation indicate that the organochlorine pesticide contamination of Yellow River and Huaihe River basins should be of particular concern relative to the other basins. When compared with other regions of the world, it appears that the Chinese surface water is moderately polluted by lindane and p,p'-DDT.