Selenium fractions in organic matter from Se-rich soils and weathered stone coal in selenosis areas of China

A high degree of association between Selenium (Se) and organic matter has been demonstrated in natural environments, but Se fractions and speciation in organic matter is unclear. In this study, a method for quantifying organic matter associated with Se (OM-Se) was developed to investigate Se fractions in organic matter in Se-rich soils and weathered stone coal from Enshi, China, where Se poisoning of humans and livestock has been documented. Initially, Se was extracted using water and a phosphate buffer. Subsequently, OM-Se was extracted using NaOH, and then speciated into Se associated with fulvic acids (FA-Se) and humic acids (HA-Se). Both FA-Se and HA-Se were further speciated into the weakly bound and strongly bound fractions using a customized hydride generation reactor. The results show that FA-Se (1.91-479 mg kg⁻¹) is the predominant form of Se in all Se-rich soils and the weathered stone coal samples, accounting for more than 62% of OM-Se (3.07-484 mg kg⁻¹). Weakly bound FA-Se (1.33-450 mg kg⁻¹) was prevalent in the total FA-Se, while weakly bound HA-Se (0.62-26.2 mg kg⁻¹) was variable in the total HA-Se (1.15-32.5 mg kg⁻¹). These data indicate that OM-Se could play a significant source and sink role in the biogeochemical cycling of Se in the supergene environment. Weakly bound FA-Se seems to act as a potential source for bioavailable Se, whereas strongly bound HA-Se is a possible OM-Se sink which is not readily transformed into bioavailable Se.     

光催化氧化处理有机废水

介绍了光催化氧化法的原理,对光催化氧化法处理有机废水的可行性进行了试验,探讨了ＣＯＤ随反应时间的变化规律及催化剂用量,温度、浓度的影响。试验表明,光催化氧化可降解象洗涤剂这样难降解的有机物,反应１２０ｍｉｎＣＯＤ去除率可达５０％以上。     

Agricultural Non-Point Source Pollution in China: Causes and Mitigation Measures

Non-point source (NPS) pollution has been increasingly serious in China since the 1990s. The increases of agricultural NPS pollution in China is evaluated for the period 2000-2008 by surveying the literature on water and soil pollution from fertilizers and pesticides, and assessing the surplus nitrogen balance within provinces. The main causes for NPS pollution were excessive inputs of nitrogen fertilizer and pesticides, which were partly the result of the inadequate agricultural extension services and the rapid expansion of intensive livestock production with little of waste management. The annual application of synthetic nitrogen fertilizers and pesticides in China increased by 50.7 and 119.7%, respectively, during 1991-2008. The mitigation measures to reduce NPS pollution include: correct distortion in fertilizer prices; improve incentives for the recycling of organic manure; provide farmers with better information on the sound use of agro-chemicals; and tighten the regulations and national standards on organic waste disposal and pesticides use.     

河南境内黄河流域集中式城市饮用水源水有机污染特性研究

摘要为探查和研究与公众生命健康关系密切的饮用水有机污染现状,采用GC／MS、HPLC、GC／ECD等多种分析技术,对河南省黄河流域部分饮用水水源地分平、丰、枯三期进行了有机物监测和研究。12个点位三期共检出599种有机物．根据毒性资料筛选出62种主要污染物。主要有毒化合物的浓度水平绝大多数远低于我国新颁布的“集中式生活饮用水地表水源地特定项目标准限值”．个别点位的极个别化合物如苯并(a)芘有超标现象．显示出明显的潜在危害作用。     

前处理方法对测汞结果影响分析

本文通过测定三种前处理方法消解后水样中汞的浓度,分析了前处理方法对测定结果的影响,以及三种前处理方法的适用条件。     

重点行业VOCs自动监控存在的问题及建议

对全国范围内石化、化工、包装印刷、工业涂装4个重点行业的VOCs自动监控设施的安装、运行和管理等情况进行调研、分析。研究发现,重点行业VOCs自动监控设施存在覆盖率不足、规范化不够、监测结果比对难、管理应用少等问题,并提出了细化自动监控设施安装要求、规范仪器市场秩序、提高自动监控质量、完善自动监控技术规范和标准、强化以用促管等建议,旨在为规范指导VOCs自动监控设施的建设、运行和提高VOCs自动监控数据的质量提供技术支撑。     

Determination of heterogeneous reaction mechanisms: A key milestone in dust explosion modelling

Reaction kinetics is fundamental for modelling the thermal oxidation of a solid phase, in processes such as dust explosions, combustion or gasification. The methodology followed in this study consists in i) the experimental identification of the reaction mechanisms involved in the explosion of organic powders, ii) the proposal of simplified mechanisms of pyrolysis and oxidation, iii) the implementation of the model to assess the explosion severity of organic dusts. Flash pyrolysis and combustion experiments were carried out on starch (22 μm) and cellulose (53 μm) at temperatures ranging from 973 K to 1173 K. The gases generated were collected and analyzed by gas chromatography. In this paper, a semi-global pyrolysis model was developed for reactive systems with low Damköhler number. It is in good agreement with the experimental data and shows that both carbon monoxide and hydrogen are mainly generated during the pyrolysis of the solid, the generation of the latter compound being greatly promoted at high temperature. A simplified combustion model was also proposed by adding two oxidation reactions of the pyrolysis products. In parallel, flame propagation tests were performed in a semi open tube in order to assess the burning velocity of such compounds. The laminar burning velocity of cellulose was determined to be 21 cm s⁻¹. Finally, this model will be integrated to a predictive model of dust explosions and its validation will be based on experimental data obtained using the 20 L explosion sphere. The explosion severity of cellulose was determined and will be used to develop and adjust the predictive model.     

两级曝气生物滤池工艺的小试研究

对两级曝气生物滤池(上向流-下向流)处理生活污水进行了试验研究。试验表明,两级曝气生物滤池在水力负荷小于4m/h,进水COD浓度变化范围为100~500mg/L,一级气水比为3∶1~5∶1,二级气水比为1∶1~2∶1的条件下,出水水质稳定,出水水质达到生活杂用水水质标准。     

有机污染场地土壤热解吸技术研究进展

文章在总结国内外研究的基础上,介绍热解吸技术原理、分类及典型旋转干燥热解吸系统,重点梳理热解吸技术运行参数(加热温度、停留时间和载气)、土壤性质(质地、粒径、含水率和有机质)和污染物性质(种类、浓度和形态)对热解吸效率影响的研究现状,评述热解吸技术强化措施(添加剂、联合其他技术)、动力学研究(常用模型、研究现状)、热解...