城市大气质量模式研究进展

本文通过对大气质量模式发展历史的回顾,及其发展趋势的讨论,认为城市大气质量预报模式的建立与发展主要受以下三个动态因素的支配：（１）政府环境管理目标;（２）科学进步;（３）计算机及信息处理和通讯技术。结合三要素就建立我国城市空气质量预报系统框架进行了讨论。     

Cyanide Removal by Chinese Vegetation. Quantification of the Michaelis-Menten Kinetics (6 pp)

Background Little is known about metabolism rates of environmental chemicals by vegetation. A good model compound to study the variation of rates among plant species is cyanide. Vascular plants possess an enzyme system that detoxifies cyanide by converting it to the amino acid asparagine. Knowledge of the kinetic parameters, the half-saturation constant (Km) and the maximum metabolic capacity (vmax), is very useful for enzyme characterization and biochemical purposes. The goal of this study is to find the enzyme kinetics (KM and vmax) during cyanide metabolism in the presence of Chinese vegetation, to provide quantitative data for engineered phytoremediation, and to investigate the variation of metabolic rates of plants. Methods Detached leaves (1.0 g fresh weight) from 12 species out of 9 families were kept in glass vessels with 100 mL of aqueous solution spiked with potassium cyanide at 23°C for 28 h. Four different treatment concentrations of cyanide were used, ranging from 0.44 to 7.69 mg CN/L. The disappearance of cyanide from the aqueous solution was analyzed spectrophotometrically. Realistic values of the half-saturation constant (KM) and the maximum metabolic capacity (vmax) were estimated by a computer program using non-linear regression treatments. As a comparison, Lineweaver-Burk plots were also used to estimate the kinetic parameters. Results and Discussion The values obtained for KM and vmax varied with plant species. Using non-linear regression treatments, values of vmax and KM were found in a range between 6.68 and 21.91 mg CN/kg/h and 0.90 to 3.15 mg CN/L, respectively. The highest vmax was by Chinese elder (Sambucus chinensis), followed by upright hedge-parsley (Torilis japonica). The lowest vmax was demonstrated by the hybrid willow (Salix matssudana x alba). However, the highest KM was found in the water lily (Nymphea teragona), followed by the poplar (Populus deltoides Marsh). The lowest KM was demonstrated by corn (Zea mays L.). The values of vmax were normally distributed with a mean of 13 mg CN/kg/h. Conclusions Significant removal of cyanide from aqueous solution was observed in the presence of plant materials without phytotoxicity, even at high doses of cyanide. This gives rise to the conclusion that the Chinese plant species used in this study are all able to efficiently metabolize cyanide, although with different maximum metabolic capacities. A second conclusion is that the variation of metabolism rates between species is small. All these plants had a similar KM, indicating the same enzyme is active in all plants. Recommendations and Outlook Detoxification of cyanide with trees seems to be a feasible option for cleaning soils and water contaminated with cyanide. For phytoremediation projects, screening appropriate plant species adapted to local conditions should be seriously considered. More chemicals should be investigated to find common principles of the metabolism of environmental chemicals by plants.     

Distribution of antibiotic-resistant bacteria in chicken manure and manure-fertilized vegetables

Veterinary manure is an important pollution reservoir of antibiotics and antibiotic-resistant bacteria (ARB). However, little is known of the distribution of ARB in plant endophytic bacteria and the number/types of ARB in chicken manure. In this study, 454-pyrosequencing was used to investigate the distribution and composition of ARBs in chicken manure and fertilized vegetables. The prevalence of ARB in the samples of the chicken manure compost recovered from farms on which amoxicillin, kanamycin, gentamicin, and cephalexin were used was 20.91–65.9 % for ARBs and 8.24–20.63 % simultaneously resistant to two or more antibiotics (multiple antibiotic resistant bacteria (MARB)). Antibiotic-resistant endophytic bacteria were widely detected in celery, pakchoi, and cucumber with the highest rate of resistance to cephalexin. The pyrosequencing indicated that the chicken manure dominantly harbored Firmicutes, Bacteroidetes, Synergistetes, and Proteobacteria and that Bacteroidetes was significantly enhanced in farms utilizing antibiotics. In the total cultivable colonies, 62.58–89.43 % ARBs and 95.29 % MARB were clustered in Bacteroidetes with the dominant species (Myroides ordoratimimus and Spningobacterium spp., respectively) related to human clinical opportunistic pathogens.     

没食子酸生产废炭渣的处理

采用热水洗涤法回收没食子酸生产废炭渣中的没食子酸,过滤炭渣经热再生处理得到热再生活性炭。研究了热水洗涤法回收没食子酸和热再生法再生活性炭的最佳工艺条件。实验结果表明,热水洗涤法回收没食子酸的优化工艺条件:废炭渣质量与热水体积比为0.15g/mL,热水洗涤时间为60min,热水洗涤温度为60℃。在此最佳工艺条件下,没食子酸回收量达52mg/g。热再生法再生活性炭的最佳工艺条件为:热再生温度500℃,热再生时间120min。在此条件下制备的热再生活性炭对亚甲基蓝的吸附量达168mg/g,热再生活性炭平均得率为57.1%。     

The variability in nutrient composition of Anaerobic Digestate granules produced from high shear granulation

This study investigates the production of organic fertilizer using Anaerobic Digestate (as a nutrient source) and limestone powder as the raw materials. A two-level factorial experimental design was used to determine the influence of process variables on the nutrient homogeneity within the granules. Increasing the liquid-to-solid ratio during granulation resulted in increased granule nutrient homogeneity. Increasing the processing time and the impeller speed were also found to increase the nutrient homogeneity. In terms of nutrients release into deionized water, the granules effectively released both potassium and phosphate into solution.