基于组合权物元分析模型的地下水水质评价

针对以往地下水水质评价中多采用单一权重法确定各评价指标权重的不足,提出基于主客观组合权重的权重计算模式,并运用权重风险度计算公式选出相对合适的组合权重,再与物元分析理念相结合,构建用于评价地下水水质的组合权物元分析模型。应用该模型对阜新新邱露天煤矿排土场淋溶水的地下水污染区的12个监测点水质进行综合评价。结果表明:研究区的1#～5#监测点水质均达到Ⅱ级以上,符合国家饮用水标准要求;6#～12#监测点水质均受到不同程度的污染,已不能饮用。评价结论与灰色关联分析法和模糊综合评价法所得结论基本一致。     

不同分子量的腐殖酸存在下2种无机砷的生物毒性效应研究

水环境中天然有机质会与砷形成络合物,进而影响砷的迁移、转化和生物毒性。研究利用超滤方法将腐殖酸(humic acid, HA)分为5个不同分子量的组分,以大型溞为受试生物,探究了不同分子量HA存在下砷对大型溞的毒性效应。结果表明,不同分子量的HA均缓解了As(Ⅲ)和As(Ⅴ)对大型溞的氧化应激损伤和细胞膜损伤,并降低了砷对MT的诱导量。其中1～30 k Da的HA对砷的缓解效果最好,1 k Da的HA毒性缓解效果最差,可能的原因是HA与砷的络合增加溶液中络合态砷的含量,而络合态砷难以进入细胞并被生物利用。不同分子量的HA对砷毒性的缓解差异与其跟砷的络合比例不同有关。     

Evaluation of the spontaneous combustion characteristics of coal of different metamorphic degrees based on a temperature-programmed oil bath experimental system

Research on the micro- and macrocharacteristics of different metamorphic degrees of coal helps improve the control and protection techniques used during spontaneous combustion. Nine coals with different properties were thoroughly investigated in this study. Fourier transform infrared spectroscopy and a self-designed temperature-programmed oil bath experimental system were adopted to analyze the molecular structure and macrocharacteristic parameters of the spontaneous combustion of coal. Additionally, the influence of particle size on spontaneous combustion was considered. Various functional groups were employed as microcharacteristic parameters to capture the principal active groups in oxidation. The gas production rate, oxygen consumption rate, gas concentration, heat energy release rate, and characteristic temperatures were evaluated as macrocharacteristic parameters to investigate the changes in coal during oxidation. The results establish that the microcharacteristics of coal molecules determine the degree of spontaneous combustion based on intrinsic properties and that changes in the macrocharacteristics of the spontaneous combustion of coal reflect the microstructural changes. The contents of the hydroxyl groups, carbonyl groups, alkyl ether and aryl ether in the coal molecules gradually decrease with the metamorphic increase. Oxygen-containing functional groups have higher reactivities and easily react with oxygen, causing the macroparameters, such as the oxygen consumption rate, the gas generation rate and the heat energy release rate, to consistently decrease with the increase of the metamorphic degree. Small-particle-size coal molecules have more active aliphatic hydrocarbons, oxygen-containing functional groups and a larger specific surface area, increasing the chances of adsorbing the oxygen of active groups and promoting the reaction between coal and oxygen. The experimental results indicate that coal samples with higher metamorphic degrees or larger sizes exhibit lower tendencies toward spontaneous combustion. Evaluation of the spontaneous combustion of coal based on a temperature-programmed oil bath experimental system is of great practical importance for preventing the spontaneous combustion of coal during storage, processing and utilization and can serve as a convenient reference for production safety in mining applications.     

基于SPA-VFRM的城市要害系统综合应急能力研究

为反映城市要害系统综合应急能力的发展现状及过程,在分析城市要害设施系统构成与面临的主要灾害类型基础上,提出从充分性、精确性、抵御性和及时性4个维度评价应急能力的思路,建立城市要害系统综合应急能力评估指标体系,并应用层次分析法与变异系数法确定指标综合权重,结合集对分析（SPA）与可变模糊识别模型（VFRM）构建城市要害系统综合应急能力的评价模型;运用该模型实证分析某市要害系统综合应急能力发展现状。实证表明:该市要害系统综合应急能力呈现“波浪式升高”的动态发展趋势,灾害抵御能力是构成综合应急能力的主要方面;3种方法的评价结果排序基本一致,表明该模型的评估结果稳健、可靠,能够有效反映城市要害系统综合应急能力发展情况。     

Effect of low-molecular weight organic acids on phosphorus release and phytoavailabilty of phosphorus in phosphate rocks added to soils

Phosphorus (P) is critically needed to improve soil fertility in many parts of the world. The use of water-soluble P fertilizers, e.g., single super-phosphate and triple super-phosphate in developing countries to improve crop production has been limited primarily by their high cost. The presence of indigenous phosphate deposits in some countries provides an incentive for direct application or local chemical treatment at low cost to improve the solubility of low reactive phosphate rocks (PRs). The use of naturally occurring low-molecular weight organic acids (LMWOAs) that are produced in soil as microbial metabolites or plant exudates from dead or living cells represents a new perspective in PR research. The LMWOAs contain various functional groups that may play a significant role in PR dissolution. Little information is available, however, about the potential of LMWOAs in releasing P from PRs. This study reports P release from 12 PRs, four each of low, medium, and high reactivity, obtained from various deposits (Kodjari, Tahoua, North Carolina, Gafsa, Khouribga, Tilemsi Valley, Central Florida, Sechura, Minjingu, North Florida, Hahotoe, and Parc W) using nine LMWOAs containing mono-, di-, and tri-carboxylic groups and a mineral acid (H₂SO₄). Laboratory studies showed that the organic acids are effective in releasing P from low and medium reactive PRs, but very ineffective in releasing P from high reactive PRs. The average amounts of P released by all the organic acids from the three types of PRs were 65.5 mmol kg⁻¹ PR from the low reactive PRs, 55.1 mmol kg⁻¹ from the medium, and 11.1 mmol kg⁻¹ from the high; those released from across all the PRs were 21.9 by the mono-carboxylic acid group, 54.2 by the di-carboxylic acid group, and 57.0 mmol P kg⁻¹ by the tri-carboxylic acid group. The P released was negatively correlated with the equilibrium pH, but positively correlated with Ca released from the PRs. Laboratory incubation studies on the release of P from PRs added to soils with or without organic acids and incubated at 25 °C for 15, 30, and 45 days showed that the percentage of plant-available P released varied considerably from 0.95 in the Kodjari PR to 40.1% in the North Carolina PR and was related to PR reactivity. A greenhouse study with corn (Zea mays L.) grown for 60 days on soils treated with PRs or with PRs mixed with organic acids showed that corn response to addition of oxalic or citric acid varied with P rates and PR sources, suggesting that organic acids have potential as amendments for increasing plant-available P in PR-treated soils.     

多环芳烃的零阶价分子连接性指数与正-辛醇/水分配系数

本文建立了准确预测多环芳烃(PAHs)及其烷基衍生物的正-辛醇/水分配系数(Kow)模型。模型表明PAHs的分配性质可用零阶价分子连接性指数(~°x~v)描述,~°x~v数值与PAHs的logKow成正比。应用本模型可以预测大范围PAHs的logKow值。     

印染废水混凝脱色技术的分子结构基础

印染废水的混凝脱色效果取决于染料分子的分子结构及其在水中的分子分散状态和染料的染色机制。大量研究结果表明，所选用的染料分子的分子结构决定了印染废水混凝脱色技术的混凝机制和混凝效果，合成絮凝剂与选择絮凝剂应充分考虑染料分子的分子结构与空间构型。     

Purification and molecular weight distribution of a key exopolysaccharide component of Bacillus megaterium TF10

Extracellular polymeric substances (EPS) are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions. Extracellular polysaccharides (EP) in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag''s reagent. Chemical characteristics, functional groups, and molecular weight (MW) distribu-tion of EP were compared with the harvested EPS and soluble microbial products (SMP). We found that the polymers of lower MW and free proteins were successfully removed by Sevag''s reagent. The higher MW components of EPS were predominantly polysaccharides, while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.     

Characteristics of molecular weight distribution of dissolved organic matter in bromide-containing water and disinfection by-product formation properties during treatment processes

The characteristics of dissolved organic matter (DOM) and bromide ion concentration have a significant influence on the formation of disinfection by-products (DBPs). In order to identify the main DBP precursors, DOM was divided into five fractions based on molecular weight (MW), trihalomethane formation potential and haloacetic acid formation potential were determined for fractions, and the change in contents of different fractions and total DBPs during treatment processes (pre-chlorination, coagulation, sand filtration, disinfection) were studied. Moreover, the relationship between bromide concentration and DBP generation characteristics in processes was also analyzed. The results showed that the main DBP precursors were the fraction with MW < 1 kDa and fraction with MW 3−10 kDa, and the DBP''s generation ability of lower molecular weight DOM (< 10 kDa) was higher than that of higher molecular weight DOM. During different processes, pre-chlorination and disinfection had limited effect on removing organics but could alter the MW distribution, and coagulation and filtration could effectively remove organics with higher MW. For DBPs, trihalomethanes (THMs) were mainly generated in pre-chlorination and disinfection, while haloacetic acids (HAAs) were mostly generated during pre-chlorination; coagulation and sand filtration had little effect on THMs but resulted in a slight removal of HAAs. In addition, the results of ANOVA tests suggested that molecular sizes and treatment processes have significant influence on DBP formation. With increasing bromide concentration, the brominated DBPs significantly increased, but the bromine incorporation factor in the processes was basically consistent at each concentration.     

煤质粉末活性炭自燃和热稳定性分析

针对煤质粉末活性炭最显著的热危险特性——自燃危险性进行试验。采用粉尘层最低着火温度测定系统对煤质粉末活性炭进行自燃试验,测定煤质粉末活性炭的最低着火温度;采用SDT Q600热重分析仪测定煤质粉末活性炭在氮气和空气气氛中以20℃/min的速率升温至700℃时的热解和燃烧特性,通过TG/DTG曲线计算其着火温度,并进行热稳定性评价。粉尘层自燃试验结果表明,煤质粉末活性炭最低着火温度为400℃,具有自燃危险性,易形成阴燃;氮气气氛中热解试验表明,热解过程经历了室温~120.0℃和280.0~700.0℃两次轻缓失重阶段,646.44℃时挥发分热失重速率最大,对应热失重速率峰值为0.082 6%/℃,自燃危险性较低;空气气氛中燃烧试验表明,燃烧过程经历了室温~95.5℃和300.0~600.0℃两次剧烈失重阶段,分别为吸附水分受热蒸发和氧化生成的有机官能团分解脱附导致,565.35℃时挥发分热失重速率最大,对应热失重速率峰值为13.20%/min,粉末较强的氧气吸附效应和较低的导热系数导致其自燃倾向较高,火灾危险性较大。