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煤栈作业中产生气载尘埃的原因之一是煤堆的风蚀。煤堆不管在工作(活堆垛)或不在工作(死堆垛)其作业情况对扬尘有很大影响。气象情况更是产生各种不同扬尘的重要因素。 为了预测新建煤场周围空气风蚀的粉尘浓度,不久前,我们编制了一套计算程序,描述大气中高密度气体的扩散过程。采用的程序中考虑了散落物的颗粒直径因素以及煤场的几何形状、面积,大气条件和尘源强度等因素。 为了得到作为大气条件因子的源强的资料,我们在许多国家不同地区的现有煤场周围进行了大量的调试工作。以大流量空气采样器采样后,测定煤场附近的粉尘浓度,分析收集在滤膜上的粉尘,并测定粉尘的粒径。测得的结果与计算程序在不同输入条件下的预报值进行比较,即可求得源强。当这一源强值输入计算程序,即可对设计中的煤栈进行预测。计算结果预测了各种不同情况下,周围区域中的粉尘浓度。一些典型的结果确在意料之中。 相似文献
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对了便于脱硫产物的收集和应用,用沉降法采样,用电子显微镜对产物气溶胶进行粒径分析,实验在民晕放电装置上,模拟含硫烟气在工况条件下,进行,电子显微镜的观测结果显示,脱硫产物粉尘结构疏松,颗粒形态不规则。根据电镜照片的统计结果,得出产物粉尘的数目中粒径NMD为0.40μm,几何标准偏差σ=5.21;质量中位么MMD为2.82μdisplay status 相似文献
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<正> (德国)鲁奇公司研制出一种把静电除尘器和计算机结合在一起的高效除尘装置.该装置以精密的微电子装置为基础.该微电子装置没有时间滞后作用,并控静电除尘器,使整个粉尘收集装置的运行达到最佳化.这是由于有两级开口除尘器控制装置的结果:第一级:由 COROMATIC~R 微型电子计算机装置控制除尘器的高压,其目的在实现最大的粉尘收尘效果;第二级:以 COROMATIC~R 控制装置 相似文献
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由于粒子重新气溶胶化的问题,使沉积在经典的惯性撞击器每一节上的量只有几毫克。因此,在用该种撞击器采集烟道样品的时候,尤其是在采集控制设备的上游样品时,必须把采样时间限制得非常短暂。大容量预分离器就是为解决上述问题而设计的一种装置,现已用单分散气溶胶和干尘对这种装置进行了检验。检验结果是,在流速为14.2升/分(0.5cfm)时,临界空气动力学直径是10.8μm,其相应的Stokes数是0.115;用Detroit Edison飞灰进行检验,结果类同;即,其动力学粒径为11.2μm。在该装置所收集的飞灰粒子中,大于15μm的气溶胶粒子有92.5%是予分离器收集的。 相似文献
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窄脉冲电晕放电烟气脱硫产物粒径分析的实验研究 总被引:1,自引:0,他引:1
为了便于脱硫产物的收集和应用,用沉降法采样,用电子显微镜对产物气溶胶进行粒径分析.实验在窄脉冲电晕放电装置上,模拟含硫烟气在工况条件下(气体流量2m3/h,反应器入口处SO2浓度2000ml/m3,SO2和NH3在通道中停留时间为5s以上,温度60℃、水蒸气体积比7.5%,相对湿度38.2%)进行.电子显微镜的观测结果显示,脱硫产物粉尘结构疏松,颗粒形状不规则.根据电镜照片的统计结果,得出产物粉尘的数目中位径NMD为0.40μm,几何标准偏差σ1=5.21;质量中位径MMD为2.82μm,几何标准偏差σ2=1.43 相似文献
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张克胜 《安全.健康和环境》2021,21(7):47-49
目的调查某石化企业聚乙烯粉尘危害现状,了解聚乙烯粉尘暴露对工人的健康影响。方法对粉尘作业岗位粉尘暴露情况、粉尘防护措施进行现场调查,检测作业现场粉尘浓度。结果聚乙烯生产装置接触聚乙烯粉尘的作业/岗位主要为包装和造粒等岗位。粉尘检测结果显示,时间加权平均浓度0.2~0.7 mg/m~3,短时间接触浓度0.4~4.1 mg/m~3,符合国家标准限值要求,但不同岗位之间,相同岗位不同作业点间有较大的差别,其中以高密度聚乙烯包装工暴露浓度最高。结论企业聚乙烯粉尘职业健康危害管控总体较好,虽然粉尘检测结果未超国家容许浓度,但不同岗位不同场所有较大差别。同时应注意加强职业人群的防控意识,以保护职业人群的身体健康。 相似文献
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Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis (DGGE) and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity (both in gene richness and diversity index values) and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor (50 mg/kg) recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos (150 mg/kg) caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos (250 mg/kg) produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes (bands) responded differently to the impact of agrochemicals: four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera. 相似文献
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Arsenic uptake by arbuscular mycorrhizal maize (Zea mays L.) grown in an arsenic-contaminated soil with added phosphorus 总被引:1,自引:0,他引:1
XIA Yun-sheng CHEN Bao-dong CHRISTIE Peter SMITH F Andrew WANG You-shan LI Xiao-lin 《环境科学学报(英文版)》2007,19(10):1245-1251
The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility. 相似文献
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Several main metabolites of benzo[a]pyrene (BaP) formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone (BP 1,6- quinone), trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP 7,8-diol), 3-hydroxybenzo[a]pyrene (3-OHBP), were identified by high-performance liquid chromatography (HPLC). The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that (1) the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; (2) the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; (3) the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% (w/v), concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites. 相似文献
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Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter. 相似文献
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DING Zhen-hu TANG Qing-he LIU Cai-e WANG Wen-hu ZHUANG Min LIN Yi-ming 《环境科学学报(英文版)》2007,19(2):200-204
Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury (HgT), combinative mercury (Hgc) and gaseous mercury (HgG), and content of total organic carbon (TOC), but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of (HgG,/HgT)1992〉(HgG/HgT)1996〉〉(HgG/HgT)2000. A simple outline of Hg release in landfill could be drawn: with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants (e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum) are capable of enriching more Hg than herbaceous plants. 相似文献
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Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA. 相似文献
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Decomposition of alachlor by ozonation and its mechanism 总被引:1,自引:0,他引:1
Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor. 相似文献
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The influence of the nonionic surfactant Tween 80 on pentachlorophenol (PCP) oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration (CMC). Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme. 相似文献
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Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes 总被引:2,自引:0,他引:2
In this study an effort has been made to use plant polyphenol oxidases; potato (Solanum tuberosum) and brinjal (Solanum melongena), for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation. 相似文献
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Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture 总被引:7,自引:0,他引:7
RemovalofheavymetalsfromsewagesludgebylowcostingchemicalmethodandrecyclinginagricultureWuQitang,NyirandegePascasie,MoCehuiF... 相似文献