连续退火机组氮气窒息事故分析及预防对策

介绍了某冷轧厂连续退火机组发生的一起氮气窒息事故,分析了水淬槽氮气产生的机理、事故发生的原因,提出了预防氮气窒息事故的对策措施.     

两次金汞齐—冷原子吸收光谱法测定大气中的痕量气态总汞

本文作者在已有仪器的基础上进行简单改装，建立了两次金汞齐—冷原子吸收光谱法测定大气中的微量气态总汞的方法。研究表明，这种方法最低检出限为０．０５ｎｇ；１００μｌ饱和汞蒸气连续测定结果表明其相对标准偏差＜１．４１％。在０～２．０ｎｇ汞量范围内标准工作曲线线性关系良好。运用该法，对贵州省万山汞矿、丹寨汞矿、清镇汞污染农田、省农科院和中国科学院地球化学研究所等地大气气态总汞进行了测定。这种分析方法还可以运用到其它环境样品微量汞的测定。     

A fluorescence-based bioassay for aquatic macrophytes and its suitability for effect analysis of non-photosystem II inhibitors

Background, Goals and Scope During the last years the miniaturization of toxicity test systems for rapid and parallel measurements of large quantities of samples has often been discussed. For unicellular algae as well as for aquatic macrophytes, fluorescence-based miniaturized test systems have been introduced to analyze photosystem II (PSII) inhibitors. Nevertheless, high-throughput screening should also guarantee the effect detection of a broad range of toxicants in order to ensure routinely applicable, high-throughput measuring device experiments which can cover a broad range of toxicants and modes of action others than PSII inhibition. Thus, the aim of this study was to establish a fast and reproducible measuring system for non-PSII inhibitors for aquatic macrophyte species to overcome major limitations for use. Methods A newly developed imaging pulse-amplitude-modulated chlorophyll fluorometer (I-PAM) was applied as an effect detector in short-term bioassays with the aquatic macrophyte species Lemna minor. This multiwell-plate based measuring device enabled the incubation and measurement of up to 24 samples in parallel. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal care products (PPCPs), which are often detected in the aquatic environment. The I-PAM was used (i) to establish and validate the sensitivity of the test system to the three non-PSII inhibitors, (ii) to compare the test systems with standardized and established biotests for aquatic macrophytes, and (iii) to define necessary time scales in aquatic macrophyte testing. For validation of the fluorescence-based assay, the standard growth test with L. minor (ISO/DIS 20079) was performed in parallel for each chemical. Results The results revealed that fluorescence-based measurements with the I-PAM allow rapid and parallel analysis of large amounts of aquatic macrophyte samples. The I-PAM enabled the recording of concentration-effect-curves with L. minor samples on a 24-well plate with single measurements. Fluorescence-based concentration-effect-curves could be detected for all three chemicals after only 1 h of incubation. After 4–5 h incubation time, the maximum inhibition of fluorescence showed an 80–100% effect for the chemicals tested. The EC50 after 24 h incubation were estimated to be 0.06 mg/L, 0.84 mg/L and 1.69 mg/L for paraquatdichloride, alizarine and triclosan, respectively. Discussion The results obtained with the I-PAM after 24 h for the herbicide paraquat-dichloride and the polycyclic aromatic hydrocarbon alizarine were in good accordance with median effective concentrations (EC50s) obtained by the standardized growth test for L. minor after 7 d incubation (0.09 mg/L and 0.79 mg/L for paraquat-dichloride and alizarine, respectively). Those results were in accordance with literature findings for the two chemicals. In contrast, fluorescence-based EC50 of the antimicrobial agent triclosan proved to be two orders of magnitude greater when compared to the standard growth test with 7 d incubation time (0.026 mg/L) as well as with literature findings. Conclusion Typically, aquatic macrophyte testing is very time consuming and relies on laborious experimental set-ups. The I-PAM measuring device enabled fast effect screening for the three chemicals tested. While established test systems for aquatic macrophytes need incubation times of ≥ 7 d, the I-PAM can detect inhibitory effects much earlier (24 h), even if inhibition of chemicals is not specifically associated with PSII. Thus, the fluorescence-based bioassay with the I-PAM offers a promising approach for the miniaturization and high-throughput testing of chemicals with aquatic macrophytes. For the chemical triclosan, however, the short-term effect prediction with the I-PAM has been shown to be less sensitive than with long-term bioassays, which might be due to physicochemical substance properties such as lipophilicity. Recommendations and Perspectives The results of this study show that the I-PAM represents a promising tool for decreasing the incubation times of aquatic macrophyte toxicity testing to about 24 h as a supplement to existing test batteries. The applicability of this I-PAM bioassay on emergent and submerged aquatic macrophyte species should be investigated in further studies. Regarding considerations that physicochemical properties of the tested substances might play an important role in microplate bioassays, the I-PAM bioassay should either be accompanied by evaluating physicochemical properties modeled from structural information prior to an experimental investigation, or by intensified chemical analyses to identify and determine nominal concentrations of the toxicants tested. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, PAHs and PPCPs which are often detected in the aquatic environment. Nevertheless, in order to ensure a routinely applicable measuring device, experiments with a broader range of toxicants and samples of surface and/or waste waters are necessary. ESS-Submission Editor: Dr. Markus Hecker (MHecker@Entrix.com)     

Subcellular distribution and toxicity of cadmium in Potamogeton crispus L

The submerged macrophyte Potamogeton crispus L. was subjected to varying doses of cadmium (0, 20, 40, 60 and 80 μM) for 7 d, and the plants were analyzed for subcellular distribution of Cd, accumulation of mineral nutrients, photosynthesis, oxidative stress, protein content, and ultrastructural distribution of calcium (Ca). Leaf fractionation by differential centrifugation indicated that 48-69% of Cd was accumulated in the cell wall. At all doses of Cd, the levels of Ca and B rose and the level of Mn fell; the levels of Fe, Mg, Zn, Cu, Mo, and P rose initially only to decline later. Exposure to Cd caused oxidative stress as evident by increased content of malondialdehyde and decreased contents of chlorophyll and protein. Photosynthetic efficiency, as indicated by the quenching of chlorophyll a fluorescence (Fv/Fm, Fo and Fm), decreased significantly, the extent of decrease being directly proportional to the concentration of Cd. Increased amounts of precipitates of calcium were noticed in the treated plants, located either outside the cell membrane or in chloroplasts, mitochondria, the nucleus, and the cytoplasm whereas control plants showed small deposits of the precipitates around surface of the vacuole membrane and in the intercellular space but rarely in the cytoplasm. Photosynthetic efficiency and oxidative stress could be used as indicators of physiological end-points in determining the extent of Cd phytotoxicity.     

复合式吸收器采样还原一体化冷原子吸收法测定大气中的汞

目的研制一种高效率采集大气中汞的吸收器.方法利用一种集大泡式与玻砂板式吸收器为一体的复合式吸收器采样,并使采样还原一体化冷原子吸收法测定大气中汞.结果平均吸收率为96%,变异系数在4%～12%之间.结论复合式吸收器采样吸收效率高,适合于大气中微量汞的测定.     

Growth, photosynthetic and respiratory responses to sub-lethal copper concentrations in Scenedesmus incrassatulus (Chlorophyceae)

In the present paper we investigated the effects of sub-lethal concentrations of Cu²⁺ in the growth and metabolism of Scenedesmus incrassatulus. We found that the effect of Cu²⁺ on growth, photosynthetic pigments (chlorophylls and carotenoids) and metabolism do not follow the same pattern. Photosynthesis was more sensitive than respiration. The analysis of chlorophyll a fluorescence transient shows that the effect of sub-lethal Cu²⁺ concentration in vivo, causes a reduction of the active PSII reaction centers and the primary charge separation, decreasing the quantum yield of PSII, the electron transport rate and the photosynthetic O₂ evolution. The order of sensitivity found was: Growth > photosynthetic pigments content = photosynthetic O₂ evolution > photosynthetic electron transport > respiration. The uncoupled relationship between growth and metabolism is discussed.     

The use of physiological characteristics for comparison of organic compounds phytotoxicity

The influence of intact (FLT) and photomodified (phFLT) fluoranthene (0.05, 0.5 and 5 μmol l⁻¹) and herbicide Basagran (5, 20, 35 and 50 nmol l⁻¹) on the germination, growth of seedlings and photosynthetic processes in pea plants (Pisum sativum L., cv. Garde) was investigated. The germination was significantly inhibited already by the lowest concentration (0.05 μmol l⁻¹) of FLT and phFLT, while Basagran caused inhibition only in higher concentrations (35 and 50 nmol l⁻¹). The growth of roots was significantly inhibited by higher concentration 5 μmol l⁻¹ of both FLT and phFLT and the shoot of seedlings was significantly influenced only by photomodified form. The length of root and shoot was inhibited already by concentration 5 nmol l⁻¹ of Basagran. Organic compounds applied on chloroplasts suspension influenced primary photochemical processes of photosynthesis. In chlorophyll fluorescence parameters, the significant increase of F₀ values and the decrease of F_V/F_M and Φ_II values by application of FLT (0.5 and 5 μmol l⁻¹) and phFLT (0.05, 0.5 and 5 μmol l⁻¹) was recorded. The maximum capacity of PSII (F_V/F_M) was influenced by the highest (50 nmol l⁻¹) and the effective quantum yield of PSII (Φ_II) already by the lowest (5 nmol l⁻¹) concentration of Basagran. Hill reaction activity decreased and was significantly inhibited by higher concentration (0.5 and 5 μmol l⁻¹) of FLT and phFLT and already by the lowest concentration (5 nmol l⁻¹) of Basagran.     

Heavy metals' content of automotive shredder residues (ASR): evaluation of environmental risk

Every year between 8 and 9 millions of vehicles in the European Union arrive to their end of life. Car wastes can have a very high metal content, falling into hazardous waste class. A preliminary evaluation of these wastes could be made by metals' leaching test runs which is the main objective of the present study. Evaluation of the total metal content was carried out by X-ray fluorescence and the mobility of these metals using two simple standardized extractions such as the TCLP (Toxicity Characterisation Leaching Procedure) of the US EPA and the German leaching test DIN 38414-S4. Additionally, an extraction test with acetone was performed in order to recognise metals bounded to organic matter. The results show that the total metal content of the ASR can overpass the established values for inert residues. Lead and zinc contents are fairly well correlated with grain-size, whilst other metals' contents do not exhibit clear grain-size dependence.     

卷烟膨胀烟丝生产线冷端CO_2泵装置的优化改进

为解决干冰膨胀烟丝生产线冷端液体工艺泵因机械密封长期超压和气缚现象造成损坏发生CO2泄漏而导致紧急停机抢修的问题,对干冰膨胀线冷端工艺罐系统进行了优化改进。在工艺泵吸口前管路引一根气相平衡管至工艺罐顶部,当泵吸口前管路有CO2液体时,输送管路内气化的CO2气体通过气相平衡管线释放回工艺罐内,不会进入工艺泵体内。应用结果表明,工艺泵内的憋压和气缚现象消失了,机械密封受到保护。改造前机械密封平均一个季度更换一次,改造后机械密封使用5年未损毁,达到保护干冰膨胀线冷端工艺泵机械密封的目的。     

典型可燃物燃烧烟尘物化特性差异性研究

开展对典型可燃物燃烧烟尘的物化特性差异性研究,是全面了解烟尘信息的基础.基于可控条件下的燃烧试验,对典型可燃物燃烧烟尘物理特性和化学组分进行了分析.通过对比分析汽油燃烧烟尘、聚苯乙烯燃烧烟尘、ABS燃烧烟尘及柴油烟尘和正庚烷烟尘的透射电镜图片,对透射电镜图的紧凑性、复杂性及灰度值进行了深入分析,探讨了燃烧烟尘的物理差异性.利用固相微萃取-气质联用技术(SPME-GC-MS),对汽油燃烧烟尘、聚苯乙烯燃烧烟尘、ABS燃烧烟尘化学组分进行了分析和对比.通过燃烧烟尘的特征物质组分的分析,得到3种燃烧烟尘在特征物质的分布和出峰时间等方面的差异性.这些差异性可作为对烟尘来源及燃烧条件等因素判别的依据.