TiO2气溶胶快速去除空气中的芥子气模拟剂

在自制反应器内,通过喷射法将纳米TiO_2分散成气溶胶形式,用以降解空气中的芥子气模拟剂二乙基硫醚(DES)。利用自行设计的一套气溶胶沉降行为评价装置,对TiO_2气溶胶的释放条件进行了优化。系统研究了相对湿度、反应温度、光强、催化剂加入量、反应物浓度等因素对DES降解速率和彻底矿化速率的影响。结果表明:TiO_2气溶胶对2.80 mg/L(近似芥子气快速致死浓度)DES降解的半衰期由涂覆型TiO_2的34.5 min缩短至8.5 min;TiO_2气溶胶光催化降解DES的最佳相对湿度为35%,此时CO_2最快生成速率可达34.64μg/(L·min),150 min内彻底矿化比例达66.1%;对于1.5 L反应器,催化剂加入量为30 mg时降解DES的量效比达到最佳状态;TiO_2气溶胶光催化适用于含低浓度DES空气的快速净化。     

2006 年南京冬季浓雾雾水的化学组分

利用2006 年12 月24~27 日南京外场观测试验资料和采集到的雾水样品化学分析资料,从雾水的化学组成及同月采集的雨水的比较、雾水离子间的相关性、雾水离子浓度与污染气体的关系等几方面,分析了南京雾水的化学特征.结果表明,南京雾水pH 值介于4.24~7.27,多呈酸性;雾水离子浓度随时间有较大变化,这与雾的宏观和微物理结构有关;雾水中离子浓度与同时期(2006 年12 月上旬)雨水中的离子浓度以及污染气体的浓度变化趋势有一致性.如,雾水SO4₂^-和NO₃^-的浓度在25 日14:30~19:55 有1 个峰值,而污染气体的峰值则相对提前,大约在13:00~14:00,随后气体和离子的浓度都逐渐降低.     

羌塘高原高寒草地植物地上地下碳氮生态化学计量特征及其影响因素北大核心CSCD

研究高寒草地的植物生态化学计量特征对认识极端气候背景下的草地生态系统功能与服务具有重要的意义. 选择羌塘高原高寒草地作为研究区,分析东西走向60个样点植物地上、地下部分的碳（C）、氮（N）含量与C：N的分布特征,及其各自的主要驱动因素. 结果表明：高寒草地植物地上部分C、N含量（38.22%、1.82%）均高于地下部分（31.11%、1.15%）,但C：N（22.08）却小于地下部分（28.88）,且地上部分C含量、C：N与地下部分存在显著性差异（P 〈 0.05）. 干燥指数与植物地上部分C含量（R^2 = 0.072,P 〈 0.05）以及C：N（R^2 = 0.15,P 〈 0.005）呈负相关关系,却与植物地下部分C：N（R^2 = 0.53,P 〈 0.001）呈正相关关系;此外,年均降水量（R^2 = 0.13,P 〈 0.005）与地上部分C含量呈负相关关系,总生物量（R^2 = 0.13,P 〈 0.01）及植被总盖度（R^2 = 0.12, P 〈 0.01）与地下部分C含量呈正相关关系;海拔与地上部分C：N亦呈正相关关系（R 2= 0.15,P 〈 0.005）,而年均温却与地下部分C：N呈负相关关系（R^2 = 0.31,P 〈 0.001）. 可见,水热条件是影响羌塘高原植物地上、地下C含量以及C：N差异的主要因素,而干燥指数可以作为较好的度量指标. （图7 表1 参46）     

水质化学需氧量、高锰酸盐指数和生化需氧量之间的关系

在我国 ,对工业废水和生活污水的化学需氧量测定主要采用重铬酸钾法 ,对清洁水和轻度污染的地表水多用高锰酸钾法 (高锰酸盐指数 )。由于测定体系酸碱度的不同 ,高锰酸钾法又有酸性法与碱性法之分。生化需氧量是一项测定耗氧量的生物方法 ,相对地表示水样中微生物可分解的有机物量。一般对于同一水样 ,ＣＯＤ、酸性高锰酸盐指数(酸性法 )、碱性高锰酸盐指数 (碱性法 )和ＢＯＤ5 这4个测试数值之间存在以下 3种数量关系 ,了解这些基本关系对分析测试工作有较大的帮助。1　酸性高锰酸盐指数 >碱性高锰酸盐指数高锰酸钾的氧化能力随溶液的酸碱…     

硫酸锰催化法测定高氯根气田水化学需氧量

文章针对高氯根气田水特点,使用硫酸锰代替GB／T11914—1989《水质化学需氧量的测定重铬酸盐法》中的硫酸银作为催化剂,确定了硫酸锰催化法测定化学需氧量的试验条件。分别在4个实验室间开展比对测试,并对川西北气矿3个典型井站高氯根气田水开展现场应用,测定结果的相对偏差均在规定范围内,取得了良好的应用效果。     

泸沽湖沉积物－水界面扩散作用对上覆水体基本化学组成的影响

通过云南泸沽湖－－半封闭深水湖泊湖水和沉积物孔隙中Ｃａ＾２＋、Ｋ＾＋、Ｎａ＾＋、ＨＣＯ３等基本组分及ＰＨ等剖面分布的研究，结果表明，这些基本组分可以自底部沉积物向上覆体扩散迁移，定量地估算了扩散通量及其对上覆水体的影响程度，说明湖泊沉积物－水界面作用在控制整个水体水化学基本组成中的起着重要的作用。     

Selective extraction and separation of Fe, Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.     

东莞：污染减排半年预警

8月3日,市环保局召开了2009年上半年污染减排预警会议,对全市污染减排工作进行了半年预警。据介绍,今年东莞市化学需氧量年减排任务为1．75万吨,上半年上报化学需氧量减排量为1．55万吨,环保部核定减排量为1．01万吨;     

Combined fluorescence and electrochemical investigation on the bindinginteraction between organic acid and human serum albumin

Human serum albumin (HSA) is a plasma protein responsible for the binding and transport of fatty acids and a variety of exogenous chemicals such as drugs and environmental pollutants. Such binding plays a crucial role in determining the ADME (absorption, distribution, metabolism, and excretion) and bioavailability of the pollutants. We report investigation on the binding interaction between HSA and acetic acid (C2), octanoic acid (C8) and dodecanoic acid (C12) by the combination of site-specific fluorescent probe, tryptophan intrinsic fluorescence and tyrosine electrochemistry. Two fluorescent probes, dansylamide and dansyl-L-proline, were employed in the displacement measurement to study fatty acid interaction with the two drug-binding sites on HSA. Intrinsic fluorescence of tryptophan in HSA was monitored upon addition of the fatty acids into HSA. Electrocatalyzed response of the tyrosine residues in HSA by a redox mediator was used to investigate the binding interaction. Qualitatively, observations made by the three approaches are very similar. HSA did not show any change in either fluorescence or electrochemistry after mixing with C2, suggesting there is no significant interaction with the short-chain fatty acid. For C8, the measured signal dropped in a single-exponential fashion, indicative of independent and non-cooperative binding. The calculated association constant and binding ratio is 3.1×106 L/mol and 1 with drug binding Site I, 1.1×107 L/mol and 1 with Site II, and 7.0×104 L/mol and 4 with the tryptophan site. The measurement with C12 displayed multiple phases of fluorescence change, suggesting cooperativity and allosteric effect of C12 binding. These results correlate well with those obtained by the established methods, and validate the new approach as a viable tool to study the interactions of environmental pollutants with biological molecules.     

Concentrations and chemical forms of potentially toxic metals in road-deposited sediments from different zones of Hangzhou, China

The 25 road-deposited sediments were collected from five different land-use zones (industrial, residential, commercial, park, and countryside) in Hangzhou, China. The concentrations of metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in these samples were determined using the ICP-AES after digestion with the mixture of HNO3-HF-HCl (aqua regia), and chemically fractionated using the modified BCR (the European Community Bureau of Reference) sequential extraction procedure. The highest metal concentration level was detected in the sample from industrial zone and commercial zone having heavy traffic. While the lowest metal level was noted in the street dust sample from residential zone, park, and countryside zone. The mobility sequence based on the sum of the BCR sequential extraction stages was: Zn (80.28%), Pb (78.68%), Cd (77.66%) ＞ Cu (73.34%) ＞ Mn (67.92%) ＞ Co (41.66%) ＞ Ni (30.36%) ＞ Cr (21.56%), Fe (20.86%). Correlation analysis and principal component analysis were applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. Factor analysis showed that these areas were mainly contaminated by three sources, namely lithology, traffic, and industry.