放射性松散污染真空吸尘装置的设计

针对普通工业吸尘器的局限性,根据放射性松散污染收集操作的需要及放射性废物最小化要求,提出了应用于放射性工作环境中的真空吸尘器设计方案。经旋风分离、滤袋过滤、高效过滤三级分离后,放射性松散污染可得到有效收集,尾气排放可达到核级排放标准,可达到保护环境、保护工作人员的效果,并实现放射性废物最小化。     

Simultaneous removal of phenanthrene and cadmium from contaminated soils by saponin, a plant-derived biosurfactant

Batch experiments were conducted to evaluate the performance of saponin, a plant-derived biosurfactant, for simultaneously removing phenanthrene and cadmium from the combined contaminated soils. Results showed that phenanthrene was desorbed from the contaminated soils by saponin with the partition of phenanthrene into surfactant micelle, meanwhile cadmium was effectively removed from the contaminated soils by the complexation of cadmium with the external carboxyl groups of saponin micelle. The efficiencies of saponin for the removal of phenanthrene and cadmium from the contaminated soils were greater than that of Triton X100 and citric acid, respectively. At concentration of 3750 mg/L, saponin has a removal rate of 87.7% and 76.2% of cadmium and phenanthrene, respectively, from the combined contaminated soil. The removals of cadmium and phenanthrene from the soils were not obviously constrained each other. Thus, saponin has the potential for the removal of heavy metal and PAHs from the combined contaminated soils.     

介质阻挡放电处理甲苯及其放电参量的研究

采用等离子体反应器介质阻挡放电产生低温等离子体处理甲苯,在分析负载等效电路的基础上,利用电压-电荷Lis-sajous图形法对气体放电过程中的放电参量进行测量研究,并探讨了相关工况参数对甲苯去除率的影响.研究结果表明,该反应器所得能量随着电压的增大而增大;气隙等效电容随着外加电压和气隙厚度的增大而减小;电压较低时.电介质等效电容变化不大,随着电压的增大迅速升高,当电压达到一定值后,电介质等效电容变化平缓;该反应器采用粗电极对甲苯的去除率优于细电极;甲苯的去除率随着放电功率的上升而提高,但是能量效率却呈降低的趋势.此外,研究发现甲苯的初始浓度与气体流量与甲苯的去除率呈反比,而与甲苯的绝对去除量呈正比.     

Distribution of phthalate esters in topsoil: a case study in the Yellow River Delta, China

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area of China. To assess the current status of phthalate esters (PAEs) of soil residues, soil samples (0～20 cm) (n?=?82) were collected in Bincheng District, at the geographic center of the YRD. PAEs were detected in all topsoil samples analyzed, which indicated that PAEs are ubiquitous environmental contaminants. Concentrations of 11 PAEs are in the range of 0.794～19.504 μg g^?1, with an average value of 2.975 μg g^?1. It was presented that PAEs pollution in this area was weak and monotonously increasing along the rural–urban gradient. Higher concentrations were observed from roadsides (and/or gutters), densely anthropogenic activities areas (such as the urbanization and industrialization), and agriculture influence district, which mainly originated from construction waste, municipal sewage, agricultural waste and pesticide, discarded plastic effusion and atmospheric depositions. Concentrations of PAEs were weakly positivity correlated with soil organic carbon content and pH, which suggested both of them can affect the distribution of PAEs. The concentration of di (2-ethylhexyl) phthalate and di-n-butyl phthalate dominated in the 11 PAEs, with the average values of 0.735 and 1.915 μg g^?1, respectively, and accounted for 92.1 % of the whole PAEs’ concentrations. No significant differences of PAE congeneric profiles were observed between our work and others previously reported, which is consistent with the use of similar commercial PAEs around the world.     

Impacts of Nomad Sedentarization on Social and Ecological Systems at Multiple Scales in Xinjiang Uyghur Autonomous Region,China

China’s government is now promoting the Nomad Sedentarization Project (NSP) in large areas of grassland as a solution for ecological restoration and poverty alleviation. To examine the effects of this policy, we conducted in-depth interviews at two of the project’s sites and examined the social and ecological systems at village, county, and catchment scales in Jinghe County of Xinjiang. We found that (1) the NSP in one village greatly improved the household standard of living and changed their resource utilization modes; (2) the success in this village can be attributed to resources imported from the social and ecological systems at larger scales, and could not be repeated in a second nearby village with different constraints; and (3) the NSP is poorly adapted to local ecosystem characteristics, and may therefore have negative impacts at larger scales. To avoid these problems, holistic assessments are necessary to judge the NSP’s impacts on social and ecological systems at multiple scales, and the program must be implemented cautiously to account for the potential risks in ecologically vulnerable areas.     

Reduction of nitrobenzene with sulfides catalyzed by the black carbons from crop-residue ashes

In this paper, three types of black carbons (BCs) named R-BC, W-BC, and C-BC were derived from rice straw ashes, wheat straw ashes, and corn straw ashes, respectively. Under room temperature and in an anaerobic aqueous solution, these three types of BCs could catalyze the reduction of nitrobenzene (NB) by sulfides rather than only act as the superabsorbent. The catalytic activities of BCs derived from different crop-residue ashes were very different and in the order of R-BC > W-BC > C-BC, since the reaction rate constants (k _obs) of NB with the BCs in the presence of 3 mM sulfides were 0.0186, 0.0063, and 0.0051 h^?1, respectively. The key catalytic active sites for NB reduction were evaluated, with four types of modified BCs and two types of tailored graphite as the model catalysts. The results indicated that BCs probably had two types of active sites for NB reduction, the microscopic graphene moieties and the surface oxygen functional groups. Since the sulfides and BCs often coexist in the environment, this BC-catalyzed reduction technology of NACs may be applied as an in situ remediation technique without the need for reagent addition.     

竹制填料生物接触氧化工艺处理污染河水

针对受污染的湖溪河水质特征,以传统弹性塑料填料做对比,研究以竹球和竹丝为填料的生物接触氧化工艺,考察填料的挂膜时间、生物量和污水处理效果;确定连续曝气和间歇曝气时反应器的最优运行工况：连续曝气时为HRT：7．5h,DO=3mg／L;间歇曝气时为厌氧1．2h、好氧6．3h交替运行。实验结果表明,与弹性塑料填料相比,竹制填料挂膜速度快,竹球填料的水处理效果最好;连续曝气最优工况下竹球填料反应器中COD、TN、NH3-N和TP的平均去除率分别为66．7％、47．9％、57．1％和30．6％;间歇曝气最优工况下竹球填料反应器中COD、TN、NH3-N和TP的平均去除率分别64．08％、39．95％、60．7％和54．68％;竹制填料可替代传统的塑料填料作为生物接触氧化工艺的载体填料。     

介质阻挡放电净化硫化氢气体的实验研究

采用介质阻挡放电等离子体技术净化恶臭气体硫化氢。考察了电压、频率、硫化氢初始浓度以及停留时间对硫化氢净化效果的影响。结果表明,介质阻挡放电可以有效消除硫化氢污染,硫化氢净化率随电压、频率以及停留时间的增加而升高,随硫化氢初始浓度增加而下降。当电压≥19kV,频率为300Hz,停留时间为1.56s,硫化氢初始质量浓度为30.1mg/m3时,硫化氢净化率接近100%。     

Enhanced desorption of phenanthrene from contaminated soil using anionic/nonionic mixed surfactant

A new approach using an anionic/nonionic mixed surfactant, sodium dodecyl sulphate (SDS) with Triton X-100 (TX100), was utilized for the desorption of phenanthrene from an artificial contaminated natural soil in an aim to improve the efficiency of surfactant remediation technology. The experimental results showed that the presence of SDS not only reduced the sorption of TX100 onto the natural soil, but also enhanced the solubilization of TX100 for phenanthrene, both of which resulted in the distribution of phenanthrene in soil-water systems decreasing with increasing mole fraction of SDS in surfactant solutions. These results can be attributed to the formation of mixed micelles in surfactant solution and the corresponding decrease in the critical micelle concentration of TX100 in mixed solution. The batch desorption experiments showed that the desorption percentage of phenanthrene from the contaminated soil with mixed solution was greater than that with single TX100 solution and appeared to be positively related to the mole fraction of SDS in surfactant solution. Thus, the anionic/nonionic mixed surfactants are more effective for the desorption of phenanthrene from the contaminated soil than a single nonionic surfactant.     

Computer Inference Of Network Of Ecological Interactions From Sampling Data

Both direct and indirect ecological interactions may occur in an ecosystem with large numbers of taxa. Traditional food web technique is a popular tool to measure the quality and health of the environment. Much of works must be done before constructing a food web for an ecosystem especially with many taxa. This food web is generally specific for some ecological interactions and fixed for a set of given species. It is therefore not an effective method for dynamic and prompt assessment of environment. Ecological interactions and their interactive intensity may be detected by sampling biological taxa in the field and by detecting various between-taxa distances or similarities. Network may clearly exhibit the complex interactions among biological taxa. Statistic tests on various distance or similarity measures and computer designs are required to infer the {network. We develop an algorithm and software to infer the network of direct or indirect ecological interactions in ecosystem. It is a prompt and effective tool in monitoring and assessment of the environment. A redundant network may be inferred and drawn by computer based on the statistic tests on sampling data or the pathway information given in HTML file. Dominant taxa may be found in the network. In total of 16 distance and similarity measures, including Euclidean distance, Manhattan distance, Pearson correlation, partial correlation, point correlation, linkage coefficients, Jaccard coefficient etc., are provided to detect taxa pairs with significant parametric or nonparametric similarities, based on randomization tests and ordinary statistic tests. Criteria to use distance and similarity measures are discussed.