Predicting organic carbon-water partitioning of hydrophobic organic chemicals in soils and sediments based on water solubility

For predicting organic carbon-water partitioning of organic pollutants in soils and sediments, a simple empirical relationship is derived from Raoult's law and fitted to data sets of experimental organic carbon normalized partition coefficients (K(oc)) and aqueous solubilities (S(i)) of 64 hydrophobic organic chemicals (HOCs) from literature including mono- and polycyclic aromatic hydrocarbons, halogenated monoaromatic and alkyl hydrocarbons, and polychlorinated biphenyls. Although over 5 orders of magnitude are covered in sorptivity (logK(oc)), the new relationship (logK(oc)=-0.85 logS(i)-0.55) predicts K(oc) with an average absolute deviation of only 0.23 log units. The relationship between K(oc) and S(i) is inverse and slightly nonlinear. The product of K(oc) times S(i) (=K(oc)( *), which indicates the theoretical maximum contaminant loading at its solubility limit per unit mass of organic carbon) is 0.098kgkg(-1) and 0.012kgkg(-1) for compounds with water solubilities of 1gL(-1) and 1mugL(-1), respectively.     

Effects of chlorine on the decrease of estrogenic chemicals

The effects of chlorination on the elimination of three estrogenic chemicals such as 17beta-estradiol, nonylphenol and bis-phenol A were investigated using yeast two-hybrid assay (YTA), estrogen receptor (ER) competition assay (ER-CA), and high-performance liquid chromatography/mass spectrometry (LC/MS). The results of YTA, ER-CA and the analysis of LC/MS indicated that the estrogenic activity of the above-mentioned three endocrine disruptors were significantly reduced as a result of chlorination. The decrease in estrogenic activity paralleled a decrease in estrogenic chemicals under the influence of free chlorine. One common characteristic of estrogenic chemicals is the presence of a phenolic ring. Considering that a phenolic ring is likely to undergo some sort of transformation in an aqueous chlorination solution, the above-mentioned results may be applied to the rest of the estrogenic chemicals in natural waters.     

Effects of toxic metals and chemicals on biofilm and biocorrosion

Microbes in marine biofilms aggregated into clusters and increased the production of extracellular polymeric substances (EPS), by over 100% in some cases, when the seawater media containing toxic metals and chemicals, such as Cd(II), Cu(II), Pb(II), Zn(II), AI(III), Cr(III), glutaraldehyde, and phenol. The formation of microbial cluster and the increased production of EPS, which contained 84-92% proteins and 8-16% polysaccharides, accelerated the corrosion of the mild steel. However, there was no quantitative relationship between the degree of increased corrosion and the toxicity of metals/chemicals towards sulfate-reducing bacteria, or the increased EPS production.     

Effects of loading rate on rock fracture: fracture characteristics and energy partitioning

By means of the Scanning Electron Microscope (SEM), an examination was performed of the fracture surfaces (including their vertical sections) of both Fangshan gabbro and Fangshan marble specimens fractured at the loading rates MPa m^1/2 s⁻¹. The results showed that one or more branching cracks near the fracture surfaces of dynamic rock specimens were clear and the cracks increased with increasing loading rates. However, such branching cracks were rarely seen near the static fracture surfaces. In addition, with the aid of the Split Hopkinson Pressure Bar (SHPB) testing system and a high-speed framing camera, the energy partitioning in the dynamic fracture process of a short rod (SR) rock specimen was analysed quantitatively. The total energy W_L absorbed by an SR specimen in the dynamic fracture process mainly consisted of the fracture and damage energy W_FD and the kinetic energy W_K of flying fragments. The energies W_L and W_K could be quantitatively calculated through stress wave measurement and high-speed photography in the SHPB testing system. Thus, the fracture and damage energy W_FD could be obtained. The results showed that: (1) the energy W_K increased with an increase in the impact speed of the striker bar or the loading rate; (2) the energy W_FD for dynamic rock fracture was markedly greater than that for static rock fracture, and the W_FD increased with an increase in the impact speed of the striker bar or the loading rate; and (3) the value W_L/W_B (W_B is the energy input into the loading system) in the case of dynamic fracture is much lower than that in the case of static fracture. In addition, the ratio decreases with an increase in the loading rate or the impact speed of the striker bar. This means that the energy utilisation decreases when the loading rate or the impact speed of the striker bar rises. Finally, some application problems are discussed in the paper.     

管理专业多媒体模拟实验室的构建

工商管理专业和工程管理专业的培养目标是使学生具有分析问题、解决问题的能力 ,将来更好地为社会服务。结合这两个专业的特点 ,从指导思想、实验室布局、软件系统和实验内容等方面提出了管理专业多媒体模拟实验室的构建方案 ,并对实验室建设和管理问题进行了探讨     

Effects of dissolved humic materials on acute toxicity of some organic chemicals to aquatic organisms

The influence of dissolved humic materials (DHM) on the acute toxicity of diazinon, tetrabromobisphenol-A (TBP), 4-chloroanilin (4-CA) and pentachlorophenol (PCP) was evaluated using the zebrafish (Brachydanio rerio Hamilton-Buchanan) and waterflea (Daphnia magna Straus). The 96-h LC₅₀ (zebrafish) and 48-h EC₅₀ values for four chemicals were determined in the presence of 0, 0.5, 5.0 and 50 TOC mg/l. The effects of DHM on the toxicity of four test chemicals to B. rerio were not observed in all of the DHM treatments. In the daphnid toxicity test, DHM significantly reduced the toxicity of diazinon and 4-CA, while no reduction of the toxicity of TBP and PCP was observed. These results indicate that the interaction between DHM and chemicals can alter the toxicity of some chemicals to D. magna.     

Effects of surface run-off on the transport of agricultural chemicals to ground water in a sandplain setting

An experiment was conducted at a depressional (lowland) and an upland site in sandy soils to evaluate the effects of surface run-off on the transport of agricultural chemicals to ground water. Approximately 16.5 cm of water was applied to both sites during the experiment, representing a natural precipitation event with a recurrence interval of approximately 100 years. Run-off was quantified at the lowland site and was not detected at the upland site during the experiment. Run-off of water to the lowland site was the most important factor affecting differences in the concentrations and fluxes of the agricultural chemicals between the two sites. Run-off of water to the lowland site ppears to have played a dual role by diluting chemical concentrations in the unsaturated zone as well as increasing the concentrations at the water table, compared to the upland site. Concentrations of chloride, nitrate and atrazine plus metabolites were noticeably greater at the water table than in the unsaturated zone at both sites. The estimated mass flux of chloride and nitrate to the water table during the test were 5-2 times greater, respectively, at the lowland site compared to the upland site, whereas the flux of sulfate and atrazine plus metabolites was slightly greater at the upland site. Results indicate that matrix flow of water and chemicals was the primary process causing the observed differences between the two sites. Results of the experiment illustrate the effects of heterogeneity and the complexity of evaluating chemical transport through the unsaturated zone.     

Predicting optimum backwash rates and expansion of multi-media filters

A new model for predicting the optimal expansion of dual and tri-media beds is developed and tested experimentally. This is used to determine the height of filter weirs in order to prevent the loss of filter media during backwash. For more accurate prediction of the expansion of the dual and tri-media filter beds it was assumed in an earlier work that the ratios of the porosities of tightly compacted beds and the porosities of the expanded beds are equal. This heuristic assumption for prediction of the exact expansion of the multi-layer filter beds is now verified theoretically.     

多媒体教室声学设计

保证教室和其他教学用房具有良好的声学听闻条件,使学生(特别是儿童)的健康和正常的发育得到保障,是学校建筑设计中最基本的要求之一;通过一多媒体教室实例,采用计算机仿真以及声学参数计算,给出其声学评价,并提出了改造建议.     

Effects of de-icing chemicals sodium chloride and potassium formate on cadmium solubility in a coarse mineral soil

Excessive use of sodium chloride (NaCl) as de-icing chemical causes environmental problems, such as elevated chloride concentrations in groundwater. On vulnerable sites, this can be avoided by using alternative organic de-icing chemicals, such as potassium formate (KHCOO). The environmental impacts of KCHOO are, however, not well known. This study reports the potential effects of NaCl and KCHOO on mechanisms controlling the mobility of cadmium (Cd) in roadside soils as a result of vehicular traffic. Changes in the solubility of Cd in a coarse mineral soil treated with these two de-icing chemicals were studied in a 50-day incubation experiment under four different moisture and temperature combinations and an initial soil Cd concentration of 3 mg kg(-1). After incubation, the distribution of soil Cd into different fractions was analyzed using a sequential extraction method. Soil pH and soil redox potential were recorded and the occurrence of Cd-Cl complexes in the soil was estimated using published stability constants. During incubation, KCHOO lowered the soil redox potential, but this was not accompanied by a decrease in the sorption capacity of oxides and the release of oxide-bound Cd into soil solution. On the other hand, elevated pH (from 4.3 to 6.7-8.5) in the formate treatments increased the sorption of Cd onto the oxide surfaces (up to 80% of total sorbed Cd). In the NaCl treatments, cation competition and formation of Cd-Cl complexes increased the water-soluble Cd fraction. Consequently, the amount of bioavailable Cd was 3.5 times smaller in the KCHOO than in the NaCl treatments.     

Adsorption of synthetic organic chemicals by carbon nanotubes: Effects of background solution chemistry

With the significant increase in the production and use of carbon nanotubes (CNTs), they will be inevitably released into aquatic environments. Therefore, the fate and transport of CNTs in aqueous solutions have attracted extensive attention. In the present work, the effects of natural organic matter (NOM), solution pH and ionic strength on adsorption of three synthetic organic chemicals (SOCs) by both pristine and surface functionalized single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) were investigated. The three SOCs (phenanthrene, biphenyl, and 2-phenylphenol) with different planarity, polarity, and hydrogen/electron-donor/acceptor ability, representing typical scenarios for the SOC-CNT interactions, were employed as probe molecules. Among the three background solution characteristics examined, NOM showed the most significant effect on SOC adsorption, while solution pH and ionic strength exhibited minimal or negligible impacts. The presence of NOM greatly suppressed the SOC adsorption by CNTs, and the impact on the SWNTs was higher than that on the MWNTs. The planarity and hydrophobicity of SOCs were two important factors determining the effects of NOM, solution pH and ionic strength on their adsorption by CNTs.     

危险化学品安全存储研究

从危险化学品的定义、范围出发,研究了不同类别的危险化学品的存储原则及管理方法.认为国家应从法律法规、标准规范层面规范危险化学品的存储,并落实各种制度的实施,通过教育、培训等手段,防范危险化学品存储事故的发生.     

化学危险品仓库的安全防火探讨

化学危险物品仓库是指一些专门用于存储易燃易爆化学品的区域,常见的化学危险物品有化学试剂、化学农药等,这些物品存放到仓库中容易发生爆炸、火灾,此时就要落实化学危险物品仓库的防火技术,这样才能提高化学危险物品仓库使用过程中的安全性.文章主要探讨化学危险物品仓库中防火技术的应用.     

电子教材在土木工程施工教学中的应用研究

1998年颁布了新的普通高等学校本科专业目录 ,其中设立了新的土木工程专业和工程管理专业 ,要求学生掌握的知识体系更加完善 ,而土木工程施工即是其中一门十分重要的专业课。土木工程施工教学如何改革 ,已探讨了多年 ,然而教学改革收效甚微 ,其中一个根本原因即在于该课程实践性太强 ,传统教材无法使学生做到理论与实践相结合 ,显然原有教学模式和教材均不能满足新形势下的教学。本文提出土木工程施工技术课程教材改革的重要内容———电子教材的的主要内容和应用前景。     

有机液体危险化学品泄漏处置策略研究

试验研究了利用高分子吸收剂处置有机液体危险化学品泄漏的相关技术,试验结果表明：高分子吸收剂可抑制有害液体的挥发;条装吸收剂可实现对流淌的液体危险化学品的100%拦截。在此基础上利用高分子吸收剂设计能够拦截有机液体危险化学品并报警的智能井盖,还可将吸收剂用于泄漏事故处置及泡沫灭火后处置。     

Fire-retardant effects of individual chemicals on Douglas Fir Plywood

The authors studied the effects of individual chemicals on flame spread, smoke density, and the heat index of Douglas Fir Plywood. Three types of tests were performed in an effort to establish a correlation relationship between test methods.     

试论危化品爆炸事故的现场处置

近年来,我国的爆炸事件数量有了明显增多的趋势,各种意外因素均有可能在一定程度上导致爆炸事件的产生,而其中一大部分的危险品爆炸与危化品有较为密切的关联,所以相关工作人员需要做好危化品爆炸事故现场的处置,并做好相应的预防,这对人员安全甚至我国的社会稳定来说都有积极的影响.     

Halon replacement chemicals: Perspectives on the alternatives

Halon 1301 has served as a be all and end all fire extinguishing chemical for 20 plus years. Its rapid extinguishing action, coupled with its low toxicity, low installed system cost and cleanliness, had made many addicts to its use in place of the traditional not-in-kind alternative approaches (water, carbon dioxide, powders, and foams). Unfortunately for the fire protection community, it, along with all other chlorine and bromine containing halogens, is being phased out of production and use due to its now well established contribution to adverse impact on stratospheric ozone. The history of the theory and experimental verification of ozone depletion and the state of local, national and global regulations pertaining to the control of ozone depleting substances will not be addressed here except for the following observation: The realization by Rowland and Molina in 1973 (published in 1974) that stratospheric chlorine could destroy ozone occurred at around the same time that halon 1301 was becoming a major factor in industrial and commercial fire protection.Presented at the International Telecommunications Fire Protection Symposium, New Orleans, Louisiana, May 15, 1992 (Revised August 19, 1992)