Mercury transportation in soil via using gypsum from flue gas desulfurization unit in coal-fired power plant

The mercury flux in soils was investigated, which were amended by gypsums from flue gas desulphurization (FGD) units of coal- fired power plants. Studies have been carried out in confined greenhouses using FGD gypsum treated soils. Major research focus is uptakes of mercury by plants, and emission of mercury into the atmosphere under varying application rates of FGD gypsum, simulating rainfall irrigations, soils, and plants types. Higher FGD gypsum application rates generally led to higher mercury concentrations in the soils, the increased mercury emissions into the atmosphere, and the increased mercury contents in plants (especially in roots and leaves). Soil properties and plant species can play important roles in mercury transports. Some plants, such as tall fescue, were able to prevent mercury from atmospheric emission and infiltration in the soil. Mercury concentration in the stem of plants was found to be increased and then leveled off upon increasing FGD gypsum application. However, mercury in roots and leaves was generally increased upon increasing FGD gypsum application rates. Some mercury was likely absorbed by leaves of plants from emitted mercury in the atmosphere.     

紧急逃生用自给式氧气呼吸器为船员的安全保驾护航——新版ISO 23269-4：2010国际标准介绍

本文主要介绍了新版ISO 23269-4：2010《船舶和海洋技术-船用氧气呼吸器-第4部分：符合IMO的IBC和IGC法规要求的紧急逃生用自给式氧气呼吸器》国际标准的制定背景、内容以及基本性能试验和要求,以对我国采用该国际标准提供帮助。     

Impact Resistance of Materials for Guards on Cutting Machine Tools—Requirements in Future European Safety Standards

Guards on machine tools are meant to protect operators from injuries caused by tools, workpieces, and fragments hurled out of the machine’s working zone. This article presents the impact resistance requirements, which guards according to European safety standards for machine tools must satisfy. Based upon these standards the impact resistance of different guard materials was determined using cylindrical steel projectiles. Polycarbonate proves to be a suitable material for vision panels because of its high energy absorption capacity. The impact resistance of 8-mm thick polycarbonate is roughly equal to that of a 3-mm thick steel sheet Fe P01. The limited ageing stability, however, makes it necessary to protect poycarbonate against cooling lubricants by means of additional panes on both sides.     

Self-Rated Physical Loads of Work Tasks Among Firefighters

Objectives. The present study sought to identify firefighters’ rated physical demands for the most frequently occurring work tasks and to determine if the ratings differed between full-time and part-time firefighters to help create a basis for the development of physical employment tests for firefighters. Methods. An extensive questionnaire was completed by 125 and 68 firefighters in 2000 and 2010, respectively. The data were analysed with the Mann-Whitney U test and binominal test and ranked on the basis of the responses in each category. Results. Significant differences were seen between the full- and part-time firefighters. The work tasks rated as the most physically strenuous in terms of aerobic fitness, muscle strength, work posture and body control by most respondents were smoke diving upstairs (carrying a hose), victim rescue in different ways, carrying a stretcher over terrain and pulling a hose. Conclusions. Physically strenuous work tasks should be included in the end-point performance variables used to select physical performance tests for firefighters. The part-time firefighters with no experience in several of the work tasks suggests that work-related exercises are important if both groups of firefighters are expected to do similar work.     

Biodegradability of PMMA Blends with Some Cellulose Derivatives

High polymer blends of Polymethyl methacrylate (PMMA) with cellulose acetate (CA) and Cellulose acetate phthalate (CAP) of varying blend compositions have been prepared to study their biodegradation behavior and blend miscibility. Films of PMMA–CA, and PMMA–CAP blends have been prepared by solution casting using Acetone and Dimethyl formamide(DMF) as solvents respectively. Biodegradability of these blends has been studied by four different methods namely, soil burial test, enzymatic degradation, and degradation in phosphate buffer and activated sludge degradation followed by water absorption tests to support the degradation studies. Degradation analysis was done by weight loss method. The results of all the tests showed sufficient biodegradability of these blends. Degradability increased with the increase in CA and CAP content in the blend compositions. The miscibility of PMMA–CA and PMMA–CAP blends have been studied by solution viscometric and ultrasonic methods. The results obtained reveal that PMMA forms miscible blends with either CA or CAP in the entire composition range. Miscibility of the blends may be due to the formation of hydrogen bond between the carbonyl group of PMMA and the free hydroxyl group of CA and CAP.     

硝化抑制剂的加量对生化需氧量值影响的探讨

BOD作为衡量水体受有机污染程度的重要指标,其反映的可生化降解性是其他参数无法替代的。在5日生化培养时间内,硝化作用的耗氧量取决于是否存在足够数量的能进行此种氧化作用的微生物,许多二级生化处理的出水和受污染较久的水体中,往往含有大量硝化微生物,因此测定这种水样时应抑制其硝化反应。通过对特定水体硝化抑制剂添加与否及加量多少对BOD5测定结果的影响,分析并探讨抑制特定水体硝化过程的最佳条件。在严格质量控制的基础上,对特定行业和环境水体的实际样品进行硝化抑制剂添加与否和加量及时间培养曲线等对比实验,通过所得到的比对数据以化学需氧量值与BOD5之间关系为基准,对硝化抑制剂的加量进行了探究。     

Recovery of copper from contaminated soil by flushing

In this work the development of a process for the recovery of copper from contaminated industrial soils is presented. Experimental tests on a standard soil contaminated with a solution of copper chloride were carried out. The metal was extracted from the contaminated soil by flushing with a 0.1 M aqueous solution of an ethylenediaminetetraacetic acid (EDTA) sodium salt. A maximum copper extraction efficiency of about 60% was observed. Copper was then separated from the extracted solution by precipitation with sodium hydroxide after addition of ferric sulfate.     

Social network analysis and valid Markov chain Monte Carlo tests of null models

Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary analysis of a network of associations among eagle rays.

Bioaccessibility of metals in soils: comparison between chemical extractions and in vitro tests

It is well-known that the total metal content in soils is not a good indicator of their harmful effects, leading to an overestimation of risks. Toxicological and environmental hazards depend on the chemical species and on its bioavailability to target organisms. Because a good estimation of bioavailability is difficult, a good compromise is to assess bioaccessibility, defined as the maximum amount of a pollutant which is potentially absorbable by a target organism. This study presents a comparison of different strategies to measure metal bioaccessibility in soils. Three procedures were applied to real soil samples with different levels of metal contamination: pseudo-total metal attack, selective sequential extractions and in vitro tests (deliberately developed to simulate human or mammals digestion). Considering the first step of the selective extraction procedure, which can provide the bioaccessible fraction for deposit-feeder organisms, data obtained for each metal were lower than those obtained from in vitro tests. Therefore, it is possible to highlight that this extraction tends to underestimate metal bioaccessibility in soils for humans, while in vitro tests certainly will overestimate bioaccessibility for organisms as invertebrates. If the sum of first and second step of sequential procedure is considered, results are quite similar to those obtained from in vitro tests, but this kind of procedure would require two days of work rather than a few hours required to perform an in vitro test. Results highlight the diversity among the differently defined bioaccessible fractions and the need to apply the most suitable procedure depending on the target organism.     

工业聚合氯化铝的形态分布及混凝效果

对铝浓度为2.50mol·l-1的聚合氯化铝.采用Al-Ferron络合比色法和烧杯混凝实验对样品的形态分布和混凝性能进行了研究.结果表明:三个工业系列样品中Al的形态分布规律基本一致,Ala随盐基度的升高而逐渐降低;Alc随盐基度的升高而升高;Alb则先随盐基度的升高而升高,达到最大值后,再随盐基度的升高而降低.同一系列样品在相同加药条件下,盐基度愈高,混凝效果愈好,Alb含量愈高,混凝效果并不一定愈好.因此,提高Alb不一定能提高混凝效果,工业产品的质量控制以及追求目标应当是尽量提高盐基度,而不是Alb的含量.