汞在环境中的污染和迁移转化

本文阐述了汞的污染及其来源和它在环境迁移转化规律 ,提出综合防治措施 ,以消灭汞中毒对人体健康的危害     

我国煤中汞含量水平及洗选过程汞流向分析

介绍了我国煤中汞含量与分布特征、煤中汞的赋存形态,分析了汞释放对环境的影响以及汞的脱除与控制技术。结果表明:我国(华南)晚三叠世(T3)煤中汞含量最高,平均含量为0.26μg/g;贫煤和无烟煤中汞含量最高,平均含量都超过0.20μg/g。含汞较高的晚三叠世、晚二叠世煤田主要分布于华南各地;多数煤中汞含量在0.300μg/g以下,但华南的江西、广西、贵州等地煤中汞含量总体水平较高;汞的赋存形态可分为有机结合态和无机结合态,煤中汞的控制方法可分为利用前脱汞、利用(燃烧)后脱汞和过程中汞形态转化。提出了煤炭洗选过程汞分布、脱除率和汞平衡等计算公式,指出了煤炭洗选过程中汞迁移行为的主要影响因素。     

Obligatory barrier crossing and adaptive fuel management in migratory birds: the case of the Atlantic crossing in Northern Wheatears (<Emphasis Type="Italic">Oenanthe oenanthe</Emphasis>)

Behaviour on migration was often suggested to be selected for time-minimising strategies. Current optimality models predict that optimal fuel loads at departure from stopover sites should increase with increasing fuel deposition rates. We modified such models for the special case of the east Atlantic crossing of the Northern Wheatear (Oenanthe oenanthe). From optimality theory, we predict that optimal time-minimising behaviour in front of such a barrier should result in a positive correlation between fuel deposition rates and departure fuel loads only above a certain threshold, which is the minimum fuel load (f _min) required for the barrier crossing. Using a robust range equation, we calculated the minimum fuel loads for different barrier crossings and predict that time-minimising wheatears should deposit a minimum of 24% fuel in relation to lean body mass (m ₀ ) for the sea crossing between Iceland and Scotland. Fuel loads of departing birds in autumn in Iceland reached this value only marginally but showed positive correlation between fuel deposition rate (FDR) and departure fuel load (DFL). Birds at Fair Isle (Scotland) in spring, which were heading towards Iceland or Greenland, were significantly heavier and even showed signs of overloading with fuel loads up to 50% of lean body mass. Departure decisions of Icelandic birds correlated significantly with favourable wind situations when assuming a migration direction towards Spain; however, the low departure fuel loads contradict a direct non-stop flight.     

建立省级危险源及隐患评估中心的构想

分析了当前全国各地重、特大事故频发势态 ;提出了全社会要形成一套严格防范事故的机制 ;强调了建立省级危险源及隐患评估中心 ,是这套严格防范事故机制的中心环节 ,详细介绍了如何建立省级危险源及隐患中心 ,从其目的、意义、所承担的主要任务、中心内基本结构 ,同时对“评估中心”建成后的水平和对社会稳定的作用作了详细的描述     

新型高分子螯合-絮凝剂制备条件的响应面法优化

以壳聚糖为原料,采用化学合成法将二硫代羧基引入到其高分子链上,制备出一种新型高分子螯合-絮凝剂二硫代羧基化壳聚糖(R′-N-(C=S)-SNa,简称DTCTS).以水样中Cd(Ⅱ)的去除率为考察对象,在单因素实验法的基础上,选取了制备DTCTS的主要影响因素,并采用中心复合设计实验和响应面分析法对DTCTS制备条件进行了优化.结果表明,建立的二次多项式模型回归性显著而失拟项不显著,决定系数R2为0.9829,模型拟合性良好;DTCTS最佳制备条件为:反应物CTS/CS2/NaOH摩尔比1:1.5:2、预反应时间30min、主反应温度60℃,此条件下制备的DTCTS对Cd(Ⅱ)的去除率可达99.52%,与模型预测值相对偏差为0.05%,模型可靠.     

电动力学作用下污染土壤中HCHs的迁移特征

为研究电动力学作用对污染土壤中HCHs迁移的影响及不同HCHs异构体间的迁移特征,以我国西南地区已停产的某HCHs(六六六)生产企业厂区的污染土壤为研究对象,分析反应时间、电压梯度、w(电解质)和pH等因素对HCHs迁移效果的影响. 结果表明:HCHs可以在电场力条件下进行有效迁移,其迁移效果随反应时间的增加而增强,并在192 h后达到稳定;增加电压梯度可以促进HCHs的迁移,最佳电压梯度为3.0 V/cm;最佳w(电解质)为2%;HCHs的迁移效果在pH为5.07时达到最佳. HCHs由阴极向阳极迁移,不同HCHs异构体在阳极的富集程度存在差异,其中α-HCH富集率最高,为210.5%~226.3%;而β-HCH、γ-HCH、δ-HCH富集率分别为72.5%~265.3%、38.5%~79.3%、57.3%~62.6%. 电动试验结束后,阴极处电导率最高,为1.2~324.4 mS/cm. P_(0.6)(距阴极的标准化距离为0.6的采样点)处最低,为0.1~70.1 mS/cm;土壤pH由阴极向阳极逐渐减小,其中阴极pH为10.31~12.05,而阳极pH为0.98~4.56. 研究显示,电动因素会对污染土壤中HCHs的迁移造成不同程度影响;不同HCHs异构体中,α-HCH迁移能力最强,β-HCH次之,γ-HCH和δ-HCH迁移能力较弱.      

Effects of reducing agent and approaching anodes on chromium removal in electrokinetic soil remediation

A soil remediation method combining in situ reduction of Cr(VI) with approaching anodes electrokinetic (AAs-EK) remediation is proposed. EK experiments were conducted to compare the effect of approaching anodes (AAs) and fixed electrodes (FEs) with and without sodium bisulfite (NaHSO₃) as a reducing agent. When NaHSO₃ was added to the soil before EK treatment, 90.3% of the Cr(VI) was reduced to Cr(III). EK experiments showed that the adverse effect of contrasting migration of Cr(III) and Cr(VI) species, which limits the practical application of this technique, was eliminated in the presence of the reducing agent. Furthermore, Tessier fractionation analysis indicated that the reducing agent changed the distribution of the chemical forms of Cr. The AAs-EK method was shown to acidize the soil as the anode moved toward the cathode and this acid front pushed the “focusing” region toward the cathode. After remediation, the pH of the soil was between 1.8 and 5.0 in AAs-EK experiments. The total Cr removal efficiency was 64.4% (except in the “focusing” region) when the reduction reaction was combined with AAs-EK method. We conclude that AAs-EK remediation in the presence of NaHSO₃ is an appropriate method for Cr-contaminated soil.     

A simulation model for Japanese sardine (Sardinops melanostictus) migrations in the western North Pacific

A two-dimensional individual-based model coupled with fish bioenergetics was developed to simulate migration and growth of Japanese sardine (Sardinops melanostictus) in the western North Pacific. In the model, fish movement is controlled by feeding and spawning migrations with passive transport by simulated ocean current. Feeding migration was assumed to be governed by search for local optimal habitats, which is estimated by the spatial distribution of net growth rate of a sardine bioenergetics model. The forage density is one of the most important factors which determines the geographical distributions of Japanese sardine during their feeding migrations. Spawning migration was modeled by an artificial neural network (ANN) with an input layer composed of five neurons that receive environmental information (surface temperature, temperature change experienced, current speed, day length and distance from land). Once the weight of the ANN was determined, the fish movement was solved by combining with the feeding migration model. To obtain the weights of the ANN, three experiments were conducted in which (1) the ANN was trained with back propagation (BP) method with optimum training data, (2) genetic algorithm (GA) was used to adjust the weights and (3) the weights of the ANN were decided by the GA with BP, respectively. BP is a supervised learning technique for training ANNs. GA is a search technique used in computing to find approximate solutions, such as optimization of parameters. Condition factor of sardine in the model is used as a factor of optimization in the GA works. The methods using only BP or GA did not work to search the appropriate weights in the ANN for spawning migration. In the third method, which is a combined approach of GA with BP, the model reproduced the most realistic spawning migration of Japanese sardine. The changes in temperature and day length are important factors for the orientation cues of Japanese sardine according to the sensitivity analysis of the weights of the ANN.     

初期通气和震荡培养提高高浓度乙醇发酵的乙醇浓度和产率

研究了氧气和震荡条件对酿酒酵母高浓度乙醇发酵的影响.结果表明,震荡是提高发酵液乙醇浓度和产率的最重要因素.与静止培养相比,在不通气情况下震荡培养使乙醇浓度提高了69%(从75.8 g L-1提高到128.1 g L-1),在通气条件下乙醇浓度提高了68.7%(从85.2 g L-1提高到to 143.8 g L-1).在最优条件下,两次补料,经54 h发酵,发酵液中乙醇浓度达到143.8 g L-1,乙醇产率与理论产率的比值为0.471 g/g(即92.20%).经分析,通气和震荡条件提高了发酵液中酿酒酵母的生物量和细胞活力.图5表1参12     

正常工况下石油类污染物在非饱和带中的运移特征分析

石油的战略储备对国家安全和经济的持续健康发展有着积极意义,但储备中的滴、漏等现象不可避免地将对地下水造成污染．本文以兰州某拟建石油储备库为例,模拟研究石油类污染物在非饱和带中的运移特征,结论认为在正常工况下,石油类污染物在非饱和带运移特征为：污染物浓度随着时间推移逐渐增加,在50年左右土层达到饱和,将对地下水造成严重污染．图4,参3．