离心脉冲静电除尘模型的除尘性能实验研究

介绍了一种直筒式离心脉冲静电除尘器，研究了其除尘效率与入口风速，直流基础电压，入口粉尘浓度等操作因素的关系；测定了在不同入口风速，不同供电情况下除尘器的分级效率，结果表明，离心脉冲静电除尘器具有结构简单，阻力损失低，除尘效率高等优点；脉冲供电能显著提高除尘器的分级效率。对粒径小于2μm的粉尘的捕集，入口风速为6.97m/s至12.79m/s时，脉并非中供电与直流供电相比，其分级效率提高10%-23%；与旋风相比，其分级效率提高37%-66%。     

Methylmercury and total mercury in estuarine organisms from Rio de Janeiro, Brazil

Guanabara Bay (GB), located in the Rio de Janeiro State, is still a productive estuary on the south-eastern Brazilian coast. It is an ecosystem heavily impacted by organic matter, oil and a number of other toxic compounds, including Hg. The present study aimed to comparatively evaluate the aquatic total mercury (THg) and MeHg contamination, and the ratios of MeHg to THg (% MeHg), in 3 species of marine organisms, Micropogonias furnieri-carnivorous fish (N = 81), Mugil spp.--detritivorous fish (N = 20) and Perna perna--filter-feeding bivalves (N = 190), which are widely consumed by the population. A total of 291 specimens were collected at the bay in different periods between 1988 and 1998. THg concentrations were determined by cold vapour AAS with stannous chloride as a reducing agent. MeHg was extracted by dithizone-benzene and measured by GC-ECD. Analytical quality was checked through certified standards. All organisms presented both low THg and MeHg concentrations and they were below the maximum limit of 1,000 micrograms Hg.kg-1 wet wt. as established for human intake of predatory fish by the new Brazilian legislation. Carnivorous fish showed higher THg and MeHg concentrations, and also % MeHg in muscle tissues, than organisms with other feeding habits and lower trophic levels. The average of THg concentrations in carnivorous fish was 108.9 +/- 58.6 micrograms.kg-1 wet wt. (N = 61) in 1990 and 199.5 +/- 116.2 micrograms.kg-1 wet wt. (N = 20) in 1998, but they presented different total length and body weights. The average THg content in detritivorous fish was 15.4 +/- 5.8 micrograms.kg-1 wet wt., whereas THg concentrations ranged from 4.1 to 53.5 micrograms.kg-1 wet wt. for the molluscs. The THg and MeHg contents of mussel varied according to the sampling point and water quality. MeHg concentration in detritivorous fish was similar to MeHg concentration in molluscs, but there was a significant difference in the MeHg/THg ratio: the carnivorous fish presented higher MeHg percentages (98%) than the detritivorous fish (54%) and the molluscs (33%). Weight-normalised average concentration of THg in carnivorous fish collected in 1990 (0.18 +/- 0.08 microgram.g-1/0.7 kg wet wt.) and in 1998 (0.16 +/- 0.09 microgram.g-1/0.7 kg wet wt.) presented no significant difference (t = 1.34; P < 0.5). In conclusion, the low THg and MeHg concentrations in the organisms from the GB ecosystem, are related to its eutrophic conditions and elevated amounts of suspended matter. In this situation, Hg could be strongly complexed or adsorbed by the particulate, which would dilute the Hg inputs and reduce its residence time in the water column, with a consequent decrease in its availability to organisms.     

生物质热解焦油脱除方法研究进展

生物质热解焦油的产生不仅降低了热解效率,影响设备运行,更危害着人类健康。通过介绍生物质热解焦油的特性及危害、对比分析目前各种不同除焦方法(文丘里法、旋风分离法、电捕焦法、高温裂解法和催化裂解法)的特点及应用前景,得出采用多种方法组合的形式进行联合除焦可显著提高焦油脱除效率。寻找用于湿法除焦的可再生利用的有机溶剂,开发经济、高效、长寿命的催化剂将成为生物质热解焦油脱除技术开发的重点。     

用脉冲电旋风除尘器处理催化剂厂分子筛尾气

介绍了脉冲电旋风除尘器的工作原理及用其处理催化剂分子筛尾气的试验情况。试验结果表明,分子筛尾气很适合脉冲电旋风除尘处理,除尘效果较好,在进气含尘质量浓度为1324．9mg／m^3时,除尘效率达89．4％左右,粉尘驱进速度达0．15～0．17m／s,比常规电除尘技术提高1倍左右。     

热带胶园土壤磷素形态和生物有效性

采用Hedley的磷素分级方法研究热带胶园土壤磷的形态,结果表明、热带胶园土壤磷主要以ResidualP、NaOH－Po和NaOH－Pi形态存在;各种形态磷的损失质量分数均高于38％;其中ResidualP和NaOH－Po的损失量最高,分别占全磷损失量的52％和16％,它们是长期耕作条件下热带胶园土壤磷两种最重要的有效磷源。     

Physico-chemical characterization of Residual Household Waste for energy recovery in insular territories: Case study of Reunion Island

Waste-to-energy is a promising approach to face the current challenge of waste overproduction in Reunion Island, a French territory. In this particular context of an isolated and tropical territory, it is essential to study the properties of potential feedstocks to choose the most appropriate conversion process. This article reports on the composition of Residual Household Waste from Reunion Island and its physico-chemical parameters. Twelve representative samples of Residual Household Waste were subjected to thermal and elemental analysis. The results showed that their composition had a significant influence on the physico-chemical properties, including calorific value. Residual Household Waste from the selective sorting (rich in wood, plastic, and sanitary textiles) as well as dry mixed RHW are the most interesting for energy recovery. Due to their high volatile matter and high carbon content, and their low moisture content, these types of waste have a high calorific value exceeding 18 MJ/kg. Furthermore, the RHW sample comply with the environmental and health criteria applied by French regulations concerning halogen and heavy metal. Thus, it seems that Residual Household Waste can be an alternative to conventional fuels used in incineration or pyro-gasification processes. However, the study also points the need for a pre-treatment process for these wastes. Indeed, it is necessary to sort them correctly in order to avoid the risks of pollution and important maintenance. And more importantly, drying beforehand is unavoidable to improve combustibility and obtain optimal energy conversion.     

旋流气浮除油装置预处理含油污水

在河南油田开展旋流气浮除油装置的现场试验,考察进水流量和曝气量对旋流气浮除油装置除油效果的影响。试验结果表明:在进水流量为1.8 m³/h、曝气量为0.5 L/min时,除油率最高达到96.03%;在不添加任何药剂的条件下,装置处理效果稳定;连续运行6 d内,进水含油量为174.57~1 193.15 mg/L时,出水含油量可以保持在137.38 mg/L以下,除油率为58.58%~94.53%。     

气旋活动对福岛核污染物扩散影响的模拟研究

基于拉格朗日粒子扩散模式FLEXPART-WRF,根据Stohl推导的日本福岛第一核电站核事故(下称福岛核事故)发生后40 d内的137Cs排放量数据,对核污染物在中尺度区域的扩散传输进行数值模拟研究,并选取近5年3次典型气旋个例(北方气旋、南方气旋和缓慢移动气旋)进行敏感性试验,以分析不同气旋系统对污染物扩散的影响. 结果表明:福岛核事故发生后,受中纬度西风带影响,核污染物主要向东部太平洋方向扩散;核事故发生后的5 d,受北方气旋和日本南部局地中尺度气旋2次气旋过程的影响,核污染物对日本本土部分地区影响较大,但影响时间不长. 典型气旋个例的敏感性模拟试验结果表明:北方气旋和南方气旋均可使核污染物对日本本土造成一定的影响,但由于气旋移动速度较快,影响日本岛的时间较短,沉降量也较小;当出现缓慢移动气旋影响日本和周边地区时,可致污染物影响日本岛的时间延长,并直接进入东亚大陆.      

The distribution,metabolism and toxicity of 14c-DDT in model aquarium tanks with fish and sediment simulating a tropical marine environment

Studies conducted on the distribution, fate and metabolism of DDT in a model ecosystem simulating a tropical marine environment of fish, Gobious nudiceps, Lethrinus harak, Gobious keinesis, Gobious nebulosis and white shrimp (Panaeus setiferus), show that DDT concentration in the water decreases rapidly within the first 24?h. Rapid accumulation of the pesticide in the biota also reaches a maximum level in 24?h before gradually declining. The bioaccumulation factors calculated for the fish species (G. keinesis) and white shrimp (P. Setiferus) were 270 and 351, respectively, after 24?h. There was a steady build up of DDT residues in the sediment during the first 24?h which continued to a maximum concentration of 6.66?ng/g in the seawater/fish/sediment ecosystem after 3 weeks and 5.27?ng/g in the seawater/shrimps/sediment ecosystem after 2.7 days. The depuration of the accumulated pesticide was slow with only 54% lost in G. nudiceps within 3 days of exposure in fresh sea water. By contrast, depuration was fast in the white shrimp, which lost 97% of the accumulated pesticide under the same conditions. DDT was found to be toxic to two of the fish species (G. nebulosis and L. harak) and to white shrimp, and the degree of toxicity was dependent on the particular species. The 24?h LC₅₀ at room temperature for the fish species G. nebulosis and white shrimp was found to be 0.011 and 0.116?mg/kg, respectively. These levels are comparable to the ones recorded for the temperate organisms. Degradation of DDT to its primary metabolites, DDE and DDD, was found in all the compartments of the ecosystem with DDE being the major metabolite in the fish, shrimps and sediment, while in seawater, DDD dominated as the major metabolite.     

热带增宽及其对中国东部亚热带森林植被的影响

全球气候变暖已是不争的事实,现今气候变暖的趋势已由每百年（1901--2000）增加0．6℃的记录升高为0．74℃（1906—2005）。其中高纬度地区增温特别显著,成为世界关注的热点。与之对比,热带地区的气候变化以及热带森林对它的反应报道甚少。事实上,自1970s中期以来,热带温度是每lO年升高0．26oC;同时气候模型预测到本世纪末热带地区温度将上升2．1-4．5℃。这些预测是有根据的,但究竟不是直接的证据。因此,本文综合了许多专家对热带地球物理学和大气层特性的多年观测、分析和研究的成果,其结论认为：至少自1979年以来许多热带大气层固有的特征发生变化并向地球极地推进和位移,这些根据是：（1）热带高空的哈德利环流增强并向极地扩展;（21位于热带边缘的亚热带射流向极地移动;（3）热带亚热带对流层顶高度和位置的变化;（4）热带高空平流层臭氧柱总量浓度的变化。据上述特征的变化证明数十年来热带向极地增宽纬度2°～5°（～8°）,一般确认为2．5°。由于热带增宽的驱动,广东50年的气温记录表明气候持续变暖,按增暖趋势推算,预估到2020年,现在的雷州半岛南部可能变成中热带;广东东南沿海将由目前的南亚热带变为北热带（占全省面积约1／3）;其余大部分地区为南亚热带;中亚热带基本上将退出广东（仅剩下东北角一偶）。此预测意味着南岭地区将成为南亚热带的边缘地。