Effect of ZnCl<Subscript>2</Subscript> impregnation ratio on pore structure of activated carbons prepared from cattle manure compost: application of N<Subscript>2</Subscript> adsorption-desorption isotherms

Activated carbons were prepared from cattle manure compost (CMC) by ZnCl₂ activation with various ZnCl₂/CMC mass ratios. Based on the N₂ adsorption-desorption isotherms, mathematical models including the Dubinin-Radushkevich (DR) equation, the α_s plot, and the Horvath-Kawazoe method were used to analyze the pore structural characteristics of the prepared activated carbons. It was found that for carbons possessing both micro-and mesopores, the DR method provided a more accurate estimation than the α_s method for the extent of microporosity. The effect of the ZnCl₂ impregnation ratio on the pore structure was discussed using the DR method. The results revealed that pore evolution involved three distinct regions with increases in the amount of impregnated ZnCl₂: raising the ZnCl₂/CMC mass ratio from 0.00 to 0.50 resulted in a 19-fold increase in micropore volume (V_me ^D) but caused no change in the mesopore volume (V_me ^D); increasing the ZnCl₂/CMC mass ratio from 0.50 to 1.00 led to an increment in V_mi ^D of about 50% and in V_me ^D of 170%; while raising the ratio from 1.50 to 2.50 caused a slight decrease in V_mi ^D but a 200% increment in the value of V_me ^D.     

新型除磷混凝剂的研制与应用＊

实验以处理金属表面所产生的磷化废水为研究对象,系统地分析了在新型混凝剂的使用过程中,pH值、温度、石灰投入量、沉降时间、助剂A等因素对脱磷效果的影响。结果表明,含磷量为18mg/L、COD为300mg/L、SS为150mg/L、pH值为5.7～6.5的废水,石灰投入量为300mg/L、沉降时间为10min左右、温度为25℃、pH值调节至9.0、加入5mL助剂A处理后,废水中磷含量为0.25～0.35mg/L、COD为80mg/L、SS为60mg/L,满足《污水综合排放标准》(GB8978—1996)中的一级标准。     

论旅游地的环境解说

环境教育是全民的、终身的教育,环境解说是环境教育的重要方式。环境解说一方面有利于保护旅游地的生态环境,另一方面也是国民环境教育网络体系中的重要节点。本文在简要介绍了海外环境解说的理论发展后,总结了美国和我国台湾省国家公园环境解说方面的成功经验,对我国旅游地环境解说系统建设提出了建议。     

Effects of cadmium on glutathione synthesis in hepatopancreas of freshwater crab, Sinopotamon yangtsekiense

Cadmium (Cd) is one of the most deleterious heavy metals in aquatic systems that could promote oxidative damage. To explore the effects of Cd exposure of a freshwater crab (Sinopotamon yangtsekiense) on hepatopancreatic glutathione (GSH) synthesis, crabs were exposed to the reagent with a dose range of 7.25-116.00 mg L(-1) for 48 h. The concentrations of GSH, oxidized glutathione (GSSG), NADPH and NADP(+), as well as the activities of enzymes involved in GSH synthesis, i.e. glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD), gamma-glutamylcysteine synthetase (gamma-GCS) were determined. Progressive depletion of cellular GSH content was observed with the increasing of Cd concentrations, while the level of GSSG remained constant. In response to Cd exposure, crabs showed significant induction of G6PD and NADPH, however, only up to moderate exposures. GR activity remained at a steady level at all exposure concentrations. The activity of gamma-GCS was significantly positively correlated with the Cd concentration. These results suggested that GSH synthesis could be activated against reactive oxygen species induced by lower Cd exposure; under the higher Cd exposure conditions, an inhibition of NADPH-dependant redox cycling and de novo GSH synthesis led to significant decrease in GSH content.     

汞蒸汽被动式检气管的初步研制

初步研制的汞蒸汽被动式检气管是建立在气体分子扩散和化学吸收原理基础上的,新制备的碘化亚铜沉淀和乙醇、甘油、硝酸混合、研碎,伴入经活化的层析硅胶,填充到检气管中,当汞蒸气进入管内时,发生显色反应,检气管显色长度的平方与汞蒸汽浓度及采样时间的乘积成线性关系,检测下限为0.001ug/mL(1h)。该法集采样与分析于一体,结构简单,不需动力,便于携带,操作方便,实验室模拟运用,其灵敏度和标准偏差令人满意。     

Enhanced bioaccumulation of cadmium in carp in the presence of titanium dioxide nanoparticles

In this study adsorption of Cd onto TiO2 nanoparticles and natural sediment particles (SP) were studied and the facilitated transports of Cd into carp by TiO2 nanoparticles and SP were assessed by bioaccumulation tests exposing carp (Cyprinus carpio) to Cd contaminated water in the presence of TiO2 and SP respectively. The results show that TiO2 nanoparticles had a significantly stronger adsorption capacity for Cd than SP. The presence of SP did not have significant influence on the accumulation of Cd in carp during the 25 d of exposure. However, the presence of TiO2 nanoparticles greatly enhanced the accumulation of Cd in carp. After 25 d of exposure Cd concentration in carp increased by 146%, and the value was 22.3 and 9.07 microg/g, respectively. And there is a positive correlation between Cd and TiO2 concentration. Considerable Cd and TiO2 accumulated in viscera and gills of the fish.     

堆肥化过程中微生物群落的动态

通过变性梯度凝胶电泳（DGGE）和平板计数法对堆肥化过程中微生物的区系动态变化进行了研究.结果表明,在堆肥化过程中,微生物数量总的趋势是细菌的数量最多,放线菌次之,真菌的数量最少,中温微生物的数量始终高于高温微生物.当发酵结束后,中温微生物的数量低于发酵初始水平,高温放线菌和高温真菌的数量试验结束后高于初始水平,高温细菌的数量在整个堆肥化过程中变化不大.通过DGGE分析表明,发酵过程中细菌的种类发生了明显的更迭现象.发酵初期Bdellovibrio、Clostridia bacterium、Bacillus、Clostridium等占优势,中期Beta proteobacterium、Petrobacter succinimandens、Nitrospirae bacterium、Clostridium等占优势,后期Clostridium、Beta proteobacterium、Paenibacillus等占优势,而在整个堆肥化过程中Clostridium都是优势种.     

DO C/N对同步硝化反硝化影响的试验研究

在序批式活性污泥反应器(SBR)内,以模拟的城市污水为处理对象,研究DO、C/N等因素对同步硝化反硝化脱氮效率的影响。研究表明:采用连续曝气工艺,在进水COD=200mg/L,NH4+-N=30mg/L条件下,控制DO在0.5～1.5mg/L范围内时,出水TN浓度为1.98～6.3mg/L,TN的平均去除率在80%以上,最高去除率达到93.74%,并可推断出在反应系统内存在好氧反硝化菌;C/N在3.3～10之间时,C/N越高,出水NO3--N浓度越低,SND效果越好。     

造纸黑液处理与多糖资源分级利用研究——分离条件对多糖含量的影响

草浆造纸黑液中含有丰富的聚糖资源,对其中低聚糖进行提取与纯化也是获得功能性低聚糖经济、有效的途径.本文提出了在分离木素的同时,最大限度回收多糖资源的工艺路线,并探讨了pH值、温度、陈放时间等对分离液中多糖含量的影响规律.在酸析黑液pH为4.0～5.0,65～70 ℃并陈化3～4 h的条件下,可从黑液固含量为49.87 g/L的麦草浆中回收多糖7.43 g/L;稻草浆中回收多糖4.91 g/L.这可为草浆造纸黑液的资源多级利用提供技术支撑.     

阳离子型聚丙烯酰胺投加量对絮体性状特征的影响

应用激光粒度仪、影像分析及沉降分析技术研究了阳离子型聚丙烯酰胺(PAM)对混凝过程絮体的粒度、强度及分形维数等微观特性及絮体沉降速率的影响.结果表明,絮体的粒度、强度及分形维数等微观特性与阳离子型PAM的投加量有关,存在一个PAM的最佳投加剂量.在此最佳投加剂量下,系统内絮体的粒度与强度最大、分形维数最小、絮体沉降速率最大.