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Comparison of microbial community between two shallow freshwater lakes in middle Yangtze basin, East China 总被引:2,自引:0,他引:2
In order to investigate the role of the microbial community in aquatic ecology and nutrient transformations in the development of eutrophication in large shallow freshwater lakes along Yangtze River, the microbial community in the depth-related sediment in Lake Chaohu and Lake Longganhu were compared. Lake Chaohu is one of the three most polluted lakes in China. However, the neighboring Lake Longganhu, a mesotrophic lake, is relatively pristine. The total phosphorous (TP) and total nitrogen (TN) concentration in water was detected at 0.193 mgl(-1) and 3.035 mgl(-1) for Lake Chaohu, 0.051 mgl(-1) and 0.774 mgl(-1) for Lake Longganhu, respectively. The population of the microorganisms with various ecological nutrient transforming functions (e.g. phosphate solubilizing, denitrifying and cellulose decomposing) and a batch of environmental parameters concerning the nutrient accumulating and transforming (e.g. total organic carbon, total nitrogen, and total phosphorous concentrations) were assayed in the depth-related sediment samples from several defined points in both lakes. The sediment samples from Lake Chaohu showed higher density of actinomycetes (P<0.05) and phosphate-solubilizing bacteria (P<0.001) and less profusion of denitrifying bacteria (P<0.05) and cellulolytic microbes (P<0.001), compared with those of Lake Longganhu. The data suggested that the current microbial community in the sediment of Lake Chaohu is in favor of sustaining or further accelerating the process of the lake eutrophication. A possible positive feedback loop which consists of sustained growth of microorganisms and gradual decline of lake eutrophic status is worth further discussing. 相似文献
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Li J Gao X Goeckner B Kollakowsky D Ramme B 《Journal of the Air & Waste Management Association (1995)》2005,55(3):258-264
The coal-fired electric utility generation industry has been identified as the largest anthropogenic source of mercury (Hg) emissions in the United States. One of the promising techniques for Hg removal from flue gas is activated carbon injection (ACI). The aim of this project was to liberate Hg bound to fly ash and activated carbon after ACI and provide high-quality coal combustion products for use in construction materials. Both bench- and pilot-scale tests were conducted to liberate Hg using a thermal desorption process. The results indicated that up to 90% of the Hg could be liberated from the fly ash or fly-ash-and-activated-carbon mixture using a pilot-scale apparatus (air slide) at 538 degrees C with a very short retention time (less than 1 min). Scanning electron microscope (SEM) evaluation indicated no significant change in fly ash carbon particle morphology following the thermal treatment. Fly ash particles collected in the baghouse of the pilot-scale apparatus were smaller in size than those collected at the exit of the air slide. A similar trend was observed in carbon particles separated from the fly ash using froth flotation. The results of this study suggest a means for power plants to reduce the level of Hg in coal-combustion products and potentially recycle activated carbon while maintaining the resale value of fly ash. This technology is in the process of being patented. 相似文献
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2016年7月于北江清远段采集21个水和表层沉积物样品,采用气相色谱质谱(GC-MS)法测定了样品中的PAHs(多环芳烃)含量,分析了北江水环境中PAHs的污染水平,并对其生态风险进行了评价.结果表明,水中ρ(∑PAHs)介于0.4~110.2 ng/L,表层沉积物中w(∑PAHs)(以干质量计,下同)在54.4~819.8 ng/g之间,平均值分别为41.7 ng/L和424.9 ng/g.与国内水体PAHs污染状况相比,北江清远段水中PAHs污染状况处于中低水平,而表层沉积物污染状况处于中等水平.运用特征比值法对PAHs来源进行分析表明,PAHs主要来源为石油泄漏、化石燃料燃烧.采用商值法对水中PAHs进行生态风险评价,∑PAHs和个别单体的最低风险浓度风险商值大于1.0而最高风险浓度风险商值小于1.0,处于中等污染水平;采用效应区间低、中值法对表层沉积物PAHs进行生态风险评价,仅个别点位表层沉积物中苊烯、蒽和二苯并[a,h]蒽超出生态效应低值,对生态环境潜在负面效应较小.研究显示,北江水和沉积物中PAHs潜在风险处于较低水平. 相似文献
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Aluminum formate (AF), a degradable and non-corrosive coagulant, was synthesized from aluminum hydroxide and formic acid. Polyamidine (PA), as a coagulation aid, was combined with AF for dye wastewater treatment. AF was characterized by XPS, FT-IR, viscosity, zeta potential, mass spectrum and XRD, and the flocculation properties of the dual-coagulation system were characterized by FT-IR and SEM. The results showed that COOH, Al2O3-Al and O2-Al bonds were formed in the AF synthesis process, and AF had a higher molecular weight and higher charge neutralization ability than PAC. The hydrolysates of AF were determined to contain Al13 Al11 and Al2, and the components of AF were confirmed to comprise a mixture including aluminum formate (C3H3AlO6) and its hydrate. When the color removal efficiency reached 100% in jar tests, the optimized dosage of AF/PA was 18.91/0.71 mg/L, while the optimized dosage of PAC/PA was 21.19/0.91 mg/L. According to the variance analysis, the interaction between AF/PA and PAC/PA were insignificant in macroscopic view. FT-IR spectrum indicated AF captured pollutant by means of CCO bond, PAC captured pollutant by δ CH, CC and δ CH. Overall, although the coagulation mechanism of AF was different from that of PAC, AF/PA showed better coagulation efficiency than PAC/PA in dye wastewater treatment. 相似文献
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目的:了解北京地区加油站职业病危害现状。方法:按照国家相关标准规范对北京市137家加油站的工作场所进行了汽油、苯、甲苯、二甲苯和噪声的检测。结果:加油站职业病危害因素浓/强度均符合国家职业接触限值要求,确定汽油为主要职业病危害因素。结论:北京市加油站职业危害较小,但长期接触低浓度的汽油,加之劳动强度大、作业时间长等特点会损害人体的免疫功能。 相似文献
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