Isolation, identification and arsenic-resistance of Acidithiobacillus ferrooxidans HX3 producing schwertmannite

Schwertmannite, a ubiquitous mineral present in iron oxyhydroxides formed in iron- and sulfate-rich acid media, favors incorporation of some toxic anions in its structure. We reported an iron-oxidizing bacterial strain HX3 from a municipal sludge that facilitates the formation of pure schwertmannite in cultures. Ferrous iron oxidation by the isolated strain HX3 was optimum at an initial pH of 2.0-3.3 and temperature of 28-35°C. Pure schwertmannite was found through bacterial oxidation of ferrous iron at an initial pH 2.8and temperature 28°C. Following 16 S rDNA gene sequence analysis the bacterial strain HX3 was identified as Acidithiobacillus ferrooxidans. The arsenic-resistance A. ferrooxidans HX3 showed the potential of environmental application in arsenic removal from the As（Ⅲ）- and iron-rich acid sulfate waters directly by As（Ⅲ） adsorption or the formation of schwertmannite in the environment.     

石化企业伤亡事故率的系统动力学仿真

针对石化企业伤亡事故率的复杂性和与企业运行的系统相关性,为了科学地预测伤亡事故率,提出了利用系统动力学对石化企业伤亡事故率进行仿真试验的方法.在对石化企业伤亡事故率进行了系统动力学分析之后,建立了石化企业伤亡事故率系统动力学仿真模型,对某石化企业进行了仿真试验,并分析了仿真试验的结果.试验应用表明,利用系统动力学对石化企业伤亡事故率进行仿真是科学有效的.     

输油管道腐蚀的修复方法

采用各种修复技术恢复腐蚀输油管道的完好性,对于确保其正常运营具有重要意义.综述了工程上广泛应用的各种修复技术及修复工艺.     

Study of inclusion complex of beta-cyclodextrin and nitrobenzene

beta-cyclodextrin can react with nitrobenzene to form an inclusion complex which is characterized by (1)H NMR and powder X-ray diffractometry. The ratio of beta-CD to NB in inclusion complex is determined as 1:1. At 25 degrees C, the dissociated constant, K(D), of the inclusion complex is measured as 6.5 x 10(-3) M in neutral solution (pH=7.0), but in alkali (pH=13.5), K(D) is 3.2 x 10(-2) M which is much larger than that measured in neutral.     

Effects of environmental factors on organochlorine pesticide residues in soils of the Guanting Reservoir area, China

Topsoil samples from 56 sites around the Guanting Reservoir, China, were measured for HCH and DDT concentrations. The total soil HCH content (including alpha-, beta-, gamma-, and delta-isomers) in these soil samples ranged from 0 to 7.33 ng x g(-1), with a mean of 0.69 ng x g(-1). These levels were considerably lower than those of the total DDT soil contents (including pp'-DDE, pp'-DDD, op'-DDT, and pp'-DDT), which ranged from 0 to 76.01 ng x g(-1), with a mean of 9.46 ng x g(-1). DDT was also found to be the major pollutant in the soil samples, accounting for approximately 93% of the total organochlorine pesticide (OCP) contents. Several environmental factors including land use, soil texture, soil taxonomy, and microbial biomass were considered to be responsible for the OCP levels observed. The data provide some insight into the effects of environmental conditions such as soil formation, agricultural cultivation, nutrient enrichment, and other anthropogenic activities on the degradation of OCPs in soils. Although the OCP residues currently are below the maximum limits set for use on agricultural land in China, and only rarely would such levels pose significant ecological concern, OCPs are highly persistent in soil and bioaccumulative. The data provided in this study are considered crucial for reservoir remediation, especially since the Guanting Reservoir will serve as one of the main drinking water sources for Beijing in the foreseeable future.     

Effect of Earthworm（Pheretima sp.） Density on Revegetation of Lead/zinc Metal Mine Tailings Amended with Soil

The objective of this study was to investigate the effects of earthworm density on the availability of nutrients and heavy metals in metal contaminated soils. Pb/Zn mine tailings were mixed throughly with a red yellow podzolic soil at the ratio （w/w） of 75：25. Earthworms （Pheretima sp.） were introduced to the mixture at four different densities, zero, three, six and nine individuals per pot planted with ryegrass （Loliun multiflorum）. The results indicated that earthworm activity significantly enhanced ryegrass shoot biomass. However, as denser earthworm population was introduced, shoot biomass tended to decrease. Earthworm activity significantly increased soil pH and availability of N, P and K in the tailings and soil mixture. There was a general tendency that uptake of Zn by ryegrass increased after earthworm inoculation, although the increase in extractable Zn in tailings and soil mixture was not significant. On the contrary, there seemed to be a lower uptake of Pb by ryegrass under earthworm inoclation, despite the fact that higher extractable Pb concentrations were observed. The present project indicated that the improved growth of ryegrass was due to improved nutrient availability and other soil conditions, by inoculation of earthworms at an appropriate rate. Further studies are needed to illustrate the relationship between metal availability and earthworm activity in the field.     

某高速公路大中桥人工挖孔桩施工安全控制技术

人工挖孔灌注桩是指主要采用人工挖孔成桩,具有施工机具操作简单,占有施工场地小,对周围建筑物影响小,桩质量可靠,可全面展开,缩短工期,造价较低等优点.近年来在工程中得到广泛应用.但挖孔桩在施工过程中,工人在井下作业,劳动条件差,安全事故多,桩基施工中发生安全事故以挖孔桩为最多.所以在实际施工中要针对以上情况采取必要的措施,防止事故的发生.做好开工前的人工挖孔桩从诞生之日起就与安全事故联系在了一起,由于施工环境的恶劣性和不可预见性,使从事这一工作的人员始终处于高度危险状态之下,加之现场安全措施的不健全,使得这种形式的桩体在施工时尤其需要加以安全方面的预防.笔者通过对人工挖孔桩施工安全控制来分析如何预防这类安全事故的发生.     

某炼化企业催化汽油吸附脱硫装置职业病危害控制效果评价

通过资料调研、现场调查与检测，将获取的资料与法律、法规和标准要求相比较，对某炼化企业催化汽油吸附脱硫装置进行了职业病危害控制效果评价。     

金属冶炼工艺重大危险因素分析及预防措施

从冶金企业金属冶炼生产的特点着手,通过统计近年来金属冶炼过程中发生的较大及以上的典型事故案例,分析金属冶炼过程中的重大危险因素及可能导致的事故后果,提出了相应的预防措施。