Variation in indoor levels of polycyclic aromatic hydrocarbons from burning various biomass types in the traditional grass-roofed households in Western Kenya

Biomass burning as fuel in the traditional grass-roofed rural households of Western Province of Kenya in open fire places, in poorly ventilated conditions, lead to accumulation of soot under the roofs. This study characterized and quantified the polycyclic aromatic hydrocarbons (PAHs) in accumulated soot in these households and determined the variation in PAHs concentrations with fuel biomass type. Soot samples collected from the households were extracted, cleaned and analysed by gas chromatography. The PAHs were identified using retention times, verified by gas chromatographic mass spectral analysis and quantified from peak area responses using the internal standard method. The PAHs levels significantly varied (P ≤ 0.05) with biomass type in the order: dung ≥ indigenous trees ≥ exotic trees ≥ shrubs and crop residues. Use of dung and wood from indigenous trees as fuel should be discouraged since they are higher emitters (P ≤ 0.05) of carcinogenic PAHs.     

芳烃羟化酶与鲫鱼组织富集多环芳烃和代谢释放的关系

为了解芳烃羟化酶与多环芳烃在鱼体内代谢的相互关系,揭示多环芳烃在生物体中的分布、迁移和转化规律,采用放射性同位素示踪方法,研究了多环芳烃¹⁴C－2,6－二甲基萘在鲫鱼鳃、肝、肌肉、胆、脂肪、肾等7种组织中的富集和释放;对鲫鱼各组织富集的多环芳烃释放与芳烃羟化酶（AHH）的相关性进行了分析。结果表明,鲫鱼7种组织均能对多环芳烃富集,不同组织表现出不同的富集水平和释放水平;多环芳烃在鱼体中的释放速度与芳烃羟化酶活力水平及其酶促产物呈负相关。     

Microbial changes in rhizospheric soils contaminated with petroleum hydrocarbons after bioremediation

Effects of bioremediation on microbial communities jn soils contaminated with petroleum hydrocarbons are a scientific problem to be solved. Changes in dominate microbial species and the total amount of microorganisms including bacteria and fungi in rhizospheric soils after bioremediation were thus evaluated using field bioremediation experiments. The results showed that there were changed dominant microorganisms including ] ] bacterial strains which are mostly Gram positive bacteria and 6 fungal species which were identified. The total amount of microorganisms including bacteria and fungi increased after bioremediation of microbial agents combined with planting maize. On the contrary, fungi in rhizospheric soils were inhibited by adding microbial agents combined with planting soybean.     

ASE萃取-SPE净化-HPLC法测定土壤中多环芳烃

建立了加速溶剂萃取-固相萃取净化-高效液相色谱测定土壤中16种多环芳烃的方法,优化了试验条件.方法线性关系良好,16种多环芳烃的检出限在0.412 ng/g～3.974 ng/g之间,空白加标试验的相对标准偏差在1.2%～12.7%之间,基质加标回收率在60.4%～126%之间.实际样品的测定结果表明该方法分离效果好,能够满足土壤分析的要求.     

Enhanced carbon tetrachloride degradation by hydroxylamine in ferrous ion activated calcium peroxide in the presence of formic acid

• Complete CT degradation was achieved by employing HA to CP/Fe(II)/FA process. • Quantitative detection of Fe(II) regeneration and HO• production was investigated. • Benzoic acid outcompeted FA for the reaction with HO•. • CO₂•⁻ was the dominant reductive radical for CT removal. • Effects of solution matrix on CT removal were conducted. Hydroxyl radicals (HO•) show low reactivity with perchlorinated hydrocarbons, such as carbon tetrachloride (CT), in conventional Fenton reactions, therefore, the generation of reductive radicals has attracted increasing attention. This study investigated the enhancement of CT degradation by the synergistic effects of hydroxylamine (HA) and formic acid (FA) (initial [CT] = 0.13 mmol/L) in a Fe(II) activated calcium peroxide (CP) Fenton process. CT degradation increased from 56.6% to 99.9% with the addition of 0.78 mmol/L HA to the CP/Fe(II)/FA/CT process in a molar ratio of 12/6/12/1. The results also showed that the presence of HA enhanced the regeneration of Fe(II) from Fe(III), and the production of HO• increased one-fold when employing benzoic acid as the HO• probe. Additionally, FA slightly improves the production of HO•. A study of the mechanism confirmed that the carbon dioxide radical (CO₂•⁻), a strong reductant generated by the reaction between FA and HO•, was the dominant radical responsible for CT degradation. Almost complete CT dechlorination was achieved in the process. The presence of humic acid and chloride ion slightly decreased CT removal, while high doses of bicarbonate and high pH inhibited CT degradation. This study helps us to better understand the synergistic roles of FA and HA for HO• and CO₂•⁻ generation and the removal of perchlorinated hydrocarbons in modified Fenton systems.     

多环芳烃污染土壤的微生物修复技术

对生物修复技术中的微生物进行了分类,并阐述了微生物生物降解土壤中多环芳烃（PAHs）的基本原理。在此基础上,分析了国内外微生物生物修复技术的发展概况,采用图示法重点综述了原位处理技术和非原位处理技术的工艺流程,并列举了相应的工程应用实例。     

AHH activity, tissue dose and DNA damage in different tissues of the scallop Chlamys farreri exposed to benzo[a]pyrene

A collaborative study was performed on scallops (Chlamys farreri) exposed to 0.5, 3 and 10 microg/L benzo[a]pyrene (B[a]P) for 20 days. The levels of aryl hydrocarbon hydroxylase (AHH) activity, B[a]P accumulation and DNA strand break were assayed in the gill and digestive gland. Results showed that AHH activity and B[a]P accumulation were significantly related to B[a]P dose. AHH activity was induced and then became stable gradually. B[a]P accumulation increased first and showed an incoming plateau. DNA strand break levels in the 0.5 and 3 microg/L B[a]P groups remained high and significantly different from control values until day 6, followed by a reduction in the gill and no recovery in the digestive gland. The 10 microg/L B[a]P groups remained significantly lower than control until the end. These results suggested that the application of comprehensive indices may give information on the actual exposure of organisms to pollutants, and also information on toxic effects.     

苯和甲苯硝化及磺化反应热危险性分级研究

首先介绍了化工工艺热安全性的内涵,并从反应过程热危险性分析的方法学出发,介绍间隙、半间歇化学反应工艺热危险性分级研究的总体思路及方法。然后,围绕甲苯和苯的硝化、磺化反应,用全自动反应量热仪(RC1e)和加速度量热仪(ARC)测定其反应过程的绝热温升(△Tad)、目标反应所能达到的最高温度(TM)、分解反应最大速率到达时间(θD)等参数。运用风险评价指数矩阵法(方法1)和基于失控过程温度参数的热危险评估法(方法2)分别对其硝化和磺化反应过程的热危险性进行了分级评估。结果表明,这两种方法具有良好的一致性;给定工艺条件下甲苯和苯的一段硝化反应过程的热危险度等级较低;而磺化反应的热危险较高。尽管这两种方法还有一定的局限性,但对于间歇、半间歇合成工艺的本质安全化设计、工艺热危险性的评估具有重要的参考价值和实用意义。     

室内多环芳烃污染源的化学组成特征研究

运用环境舱模拟源排放的方法采集了烹调油烟与环境烟草烟雾的样本,对18种PAHs进行了定量分析.比较了不同食用油与不同品牌香烟产生PAHs组成特征的差异,初步建立了2类室内PAHs来源的化学成分谱.结果表明:烹调油烟中3环以下的PAHs为主体,Fluo,Pyr和Flu相对含量较为稳定;香烟烟雾以3～4环组分为主体,Flu,Phe,InP和BaA较为稳定,Cor含量较烹调油烟而言显著增加.2类源的ρ(BaA)/ρ(Chy),ρ(BeP)/ρ(BaP)与ρ(InP)/ρ(BghiP)稳定且存在显著差异,可以用来解析室内PAHs以及PAHs暴露的来源.运用等效毒理学因子估算了其危害程度,结果表明:每100 g食用油在烹调过程(60 min)中释放产生PAHs的毒理学效应仅为吸烟过程中每g烟草所产生PAHs毒理效应的一半.      

Estimation and comparison of night-time OH levels in the UK urban atmosphere using two different analysis methods

Night-time OH levels have been determined for UK urban surface environments using two methods,the decay and steady state approximation methods.Measurement data from the UK National Environmental Technology Centre archive for four urban sites(Bristol,Harwell,London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study.Three reactive alkenes,namely isoprene,1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method.Hourly measurements o...