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771.
Zhao Peng Zhu Tong Liang Baosheng Hu Min Kang Ling Gong Jicheng 《Frontiers of Environmental Science & Engineering in China》2007,1(2):159-165
Agricultural activity is one of the most important sources of aerosol particles. To understand the mass distribution and sources
of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing, particle samples were collected
using a microorifice uniform deposit impactor (MOUDI) in the summer of 2004 in a suburb vegetable field. The distribution
of the particles and their inorganic water-soluble ions in the diameter range of 0.18–18 μm were measured. The dominant fine
particle ions were SO4
2−, NO3
−, and NH4
+. The association of day-to-day variation of the concentration of these ions with temperature, humidity, and solar radiation
suggested that they are formed by the reaction of NH3 released from the vegetable field with the acid species produced from photochemical reactions. Fine particle K+ is likely from vegetation emission and biomass burning. Coarse particles like Ca2+, Mg2+, NO3
−, and SO4
2− are suggested to come from the mechanical process by which the soil particle entered the atmosphere, and from the reaction
of the acid species at the surface of the soil particle. The results show that fertilizer and soil are important factors determining
the aerosol particle over agricultural fields, and vegetable fields in suburban Beijing contribute significantly to the aerosol
particle.
Translated from Environmental Science, 2006, 27(2): 193–199 [译自: 环境科学] 相似文献
772.
At the compacted, north-south line of the ice edge, phytoplankton were sampled during early austral autumn of 1986 in the northwestern Weddell Sea. Cells from discrete water bottle samples from 12 stations on two east-west transects were counted to gain quantitative information on the composition, abundance, distribution, and condition of the phytoplankton in water-column assemblages. Over 70 species were found. The highest numbers of total cells (integrated through the top 150 m) were found in open water, well-separated from and to the east of the ice edge on the southern transect, with 6.01×1010 cells m-2. The relative abundance of diatoms was low at ice-convered stations (< 35% of the total phytoplankton in preserved samples) and high at open-water stations (> 80%); however, the relative abundance of the prymnesiophyte Phaeocystis sp. was high at ice-covered stations (> 60%) and low at open-water stations (< 16%), with lower absolute abundances than during a previous austral-spring phytoplankton increase. In the open ocean, the dominants were the pennate diatoms Fragilariopsis cylindrus, Pseudonitzschia prolongatoides, F. curta, and a small form of the centric diatom Chaetoceros dichaeta in chains. Although the three pennate diatoms were frequently dominant in number, they represented less biomass than C. dichaeta in open waters. Mean phytoplankton abundance was low (0.2×106 cells l-1) but, overall, the diatom cell density (0.14×106 cells l-1) was similar to that found previously during a northward transect from ice-covered to ice-free water at the Weddell-Scotia Sea ice edge (spring 1983). The phytoplankton spatial patterns in the two autumn transects differed, with the more southerly transect exhibiting a higher abundance of diatoms and dinoflagellates. The ratio of full to empty diatoms was higher on the southern transect, indicating a healthy population, while lower ratios of full/empty frustules on the northern transect suggested a generally declining population. However, Phaeocystis sp. was more abundant on the northern transect. 相似文献
773.
774.
The major emission sources of carbon dioxide, methane, nitrous oxide and CFCs in China have been identified, and the emission trends has been estimated. Besides fossil fuel combustion, human respiration and biomass burning are important sources. Some feasible abatement measures on energy conservation, afforestation and biomass recycling have been discussed. 相似文献
775.
钢材混酸酸洗中NO_x与酸雾综合治理技术的研究与应用 总被引:1,自引:0,他引:1
采用硝酸与其它酸的混合酸对特殊钢进行表面处理时,会产生大量的NOx和其它挥发性酸雾,是冶金企业的主要污染源之一。在金属酸洗过程中以投加化学抑制剂的方法控制NOx污染,同时以水洗涤、吸收的方法治理其它挥发性酸雾,是治理这种污染的行之有效的综合治理技术。本文简要介绍了化学抑制法控制NOx的基本原理,模拟试验的方法以及综合治理技术在工程中应用情况,以供参考。 相似文献
776.
硫酸盐还原——甲烷化两相厌氧处理工艺中的回流比研究 总被引:4,自引:0,他引:4
以硫酸盐还原—产甲烷两相厌氧新型工艺处理含高浓度硫酸盐有机废水,气提塔出水的回流比的操作选择十分关键。根据、电离平衡理论及最佳工艺条件要求(液相中的C_L(H_2S)≥208mg/L,c(S~(2-))≤500mg/L)推导出估算回流比的模型为[Bc_0(SO_4~(2-))/1500-1]/η≤R≤[Bc_0(SO_4~(2-))(1.49×10~(pH-7) 1)~(-1)/588-1]/η。以该模型为依据处理SO_4~(2-)浓度为10000mg/L合成废水时,得到总COD去除率和总硫酸盐还原率分别为92.6%和97.6%。 相似文献
777.
康冠军 《石油化工环境保护》2004,27(3):20-25
针对洛阳石化PTA污水处理装置存在的主要问题,通过分析,提出了相应对策,优化了生产操作,提高了装置的处理水平,保证了污水的达标排放。 相似文献
778.
779.
The atmospheric concentrations of dimethylsulfide (DMS) and carbon disulfide (CS2) were measured concurrently with relevant environmental parameters at Gosan, Jeju Island, Korea during 5-26 April 2001. The mean concentrations for these two compounds were 18.7+/-17.9 and 6.4+/-9.9 pptv, respectively. Results of our analysis indicated that relative temporal variations between DMS and CS2 can be best described by dividing the whole data set into three different periods which reflect the variable transport patterns of air masses into the study area. (Periods I, II, and III denote: 5-10, 10-18, and 19-26 April.) The environmental conditions during those three periods varied greatly. The effects of continental and/or oceanic processes were evident for certain periods, yielding diverse relationships between DMS and CS2 in both absolute and relative terms. Most observed variations were best explained in terms of an interplay between source/sink processes and air mass transport patterns. The sea-to-air flux of DMS, when estimated using our measurement data during this study period, was approximately 4 micromole m(-2)d(-1). 相似文献
780.
Encapsulation technology is being investigated as a method for controlling pH in situ at contaminated groundwater sites where pH may limit remediation of organic contaminants. This study examined the effectiveness of using KH2PO4 buffer encapsulated in a pH-sensitive coating to neutralize pH in laboratory sand columns (1.5-1) under a simulated groundwater flow rate and characterized the pattern of capsule release in the flow-through system. Denitrification was used in the columns to increase the pH of the pore water. Each of three columns was equipped with three miniature mesh wells to allow contact of the buffer with column pore water, but capsules (15 g) were inserted into only one column (amended). The two other columns served as amendment (no buffer) and abiotic (no denitrification) controls. Oxidation-reduction potential, dissolved organic and inorganic carbon, NH4+, NO3- +NO2-, PO(4)3-, and pH were measured in the influent, two side ports, and effluent of the columns over time. Near complete conversion of 80 mg N/1 of nitrate and 152 mg/l of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the amendment control column. The amended column maintained the target pH of 7.0 +/- 0.2 for 4 weeks until the capsules began to be depleted, after which time the pH slowly started to increase. The capsules exhibited pulses of buffer release, and were effectively dissolved after 7.5 weeks of operation. Base-neutralizing capacity contributed by the encapsulated buffer over the entire study period, calculated as cation equivalents, was 120 mM compared to 8 mM without buffer. This study demonstrates the potential for this technology to mediate pH changes and provides the framework for future studies in the laboratory and in the field, in which pH is controlled in order to enhance organic contaminant remediation by pH-sensitive systems. 相似文献