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911.
Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel (Pd/foam-Ni) and palladium/polymeric pyrrole film/foam-nickel (Pd/PPy/foam-Ni) composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope (SEM) micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode. 相似文献
912.
ZHAO Xingqing YANG Liuyan YU Zhenyang PENG Naiying XIAO Lin YIN Daqiang QIN Boqiang 《环境科学学报(英文版)》2008,20(2):224-230
The characterization of microbial communities of different depth sediment samples was examined by a culture-independent method and compared with physicochemical parameters, those are organic matter (OM), total nitrogen (TN), total phosphorus (TP), pH and redox potential (Eh). Total genomic DNA was extracted from samples derived from different depths. After they were amplified with the GC-341 f/907r primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis (DGGE). The profile of DGGE fingerprints of different depth sediment samples revealed that the community structure remained relatively stable along the entire 45 cm sediment core, however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. The principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into two groups, which were located 0-20 cm and 21-45 cm, respectively. The sequencing dominant bands demonstrated that the major phylogenetic groups identified by DGGE belonged to Bacillus, Bacterium, Brevibacillus, Exiguobacterium, γ-Proteobacterium, Acinetobacter sp. and some uncultured or unidentified bacteria. The results indicated the existence of highly diverse bacterial community in the lake sediment core. 相似文献
913.
914.
世博园区水体底泥氮磷分布特征 总被引:2,自引:1,他引:1
分析世博园区水体底泥中氮磷营养盐、硫化物和有机质含量,结果表明,硫化物为(4.51±0.12)mg/kg,有机质为(1.73±0.01)%,氨氮为(206.6±1.2)mg/kg,亚硝酸盐氮为(0.041±0.001)mg/kg,硝酸盐氮为(0.066±0.002)mg/kg,总氮为(0.228±0.002)%,速效磷为(192.3±0.5)mg/kg,总磷为(0.247±0.001)%。运用有机指数评价底泥污染,为0.299±0.005,说明污染较严重。 相似文献
915.
Yan ZHANG Xiang GAO Zhenyu ZHONG Xihai DENG Buzhuo PENG 《Frontiers of Environmental Science & Engineering in China》2008,2(3):370-379
Through the use of general sampling and measurement by 137 Cs dating, problems regarding the absence of monitoring data can easily be resolved. Further, weighted values need to be
determined while Environment Quality Comprehensive Index (EQCI) is commonly used as applied in environmental quality comprehensive
evaluation. In order to overcome the subjectivity in determining weights, the modified Analytical Hierarchy Process (AHP)
method was designed. The modified AHP method involved the following key procedures: First, the parameters y
i1 and y
i2 were calculated based on the monitoring data; second, the factors were put in order according to the symbol and value of
y
i1 and y
i2; third, the continuous odd integers, which represented the importance of factors, were given to factors according to their
seating order; and, fourth, the factor weights were determined from the pair-wise comparison matrix calculated by the ratio
of the given odd integers. Therefore, the weights were completely based on the monitoring data. In the present study, the
comprehensive quality of sediments in five sections of Lake Dianchi were evaluated and the results indicated that the current
contamination of sediments in each lake section is much more serious than at any other time in history.
__________
Translated from Environmental Science, 2006, 27(8): 1531–1536 [译自: 环境科学] 相似文献
916.
二氧化锰氧化降解五氯酚的动力学模拟研究 总被引:1,自引:0,他引:1
研究了五氯酚(PCP)在二氧化锰(MnO2)氧化作用下的降解反应动力学,并讨论了无机离子和有机组分对PCP降解动力学的影响.采用n级反应速率模型对PCP降解动力学进行非线性拟合,结果显示n>0.999,这表明一级反应速率模型适用于模拟PCP降解反应.在保证95%置信区间的条件下,采用准一级反应速率模型对0.5 h内的PCP降解动力学进行了非线性拟合,得到的离心法和维生素C破坏法下PcP降解表观速率常数kobs分别是2.86和2.14 h-1.二价金属离子的加入能降低PCP的kobs;当超过MnO2初始浓度2%以上的Mn2 存在时,Mn2 能对PCP的kobs产生显著影响,而其它不同类型和浓度的离子对kobs不产生显著影响.8种酚酸中的咖啡酸、丁香酸和五倍子酸对kobs的抑制作用达到了显著性水平;而肉桂酸、香豆酸、阿魏酸和邻(对)羟基苯甲酸的影响不明显.研究表明,降低PCP降解速率的主要原因是由于导致PCP在MnO2表面的吸附作用减弱或在MnO2表面与PCP发生竞争反应造成的. 相似文献
917.
918.
广州市大气TSP浓度变化及其与气象因子的关系 总被引:1,自引:0,他引:1
利用实地监测大气TSP浓度和局地气象数据,研究了2005年至2006年广州市不同功能区大气TSP浓度变化及其与气象因子的关系。结果表明,工业区大气TSP月平均浓度0.273mg/m3最高,显著高于交通繁忙区的0.207mg/m3;极显著高于商业区的0.180mg/m3、社区的0.155mg/m3和对照郊区的0.142mg/m3。研究显示,广州市大气TSP污染仍然比较严重。广州市大气TSP浓度与降雨呈现负相关性,与温度呈极显著的负相关性,与相对湿度呈显著的负相关性,与风速呈负相关性,与风向的相关性不明显。各功能区大气TSP浓度与局地气象因子也存在类似的规律。 相似文献
919.
南海北部大陆架海洋生态系统演变的Ecopath模型比较分析 总被引:7,自引:1,他引:6
过度捕捞和环境恶化导致渔业资源和海洋生态系统逆向发展.采用EwE5.1(Ecopath with Ecosim)软件,对南海北部大陆架分别建立20世纪80年代末期(1989~1992年)、20世纪90年代末期(1997~2000年)和21世纪初期三个代表时间段的Ecopath(生态通道模型)模型.通过三阶段的流量、生物量、生产量、捕捞量、系统总流量、总循环流量以及Finn's循环指数和Finn's平均路径长度等方面的比较分析,得出近20 a的过度捕捞导致系统与渔业资源逐渐"退化".20世纪90年代末期休渔政策对此有一些缓和作用,但总趋势不变. 相似文献
920.
珠江口及南海近海海域大气多环芳烃分布特征 总被引:3,自引:0,他引:3
分冬、春两次航次分别采集了珠江口及南海近海海域大气气溶胶样品和气相样品,同时以广州和中山作为陆基对照点,对16种EPA优控多环芳烃进行了分析.结果表明,大气PAHs主要以气态化合物为主,总PAHs(气态+颗粒态)的含量范围为49.6~256.6 ng/m3,平均120.7 ng/m3.珠江口海域大气颗粒态多环芳烃季节变化显著,冬、春航次大气颗粒态多环芳烃的含量分别为6.7~18.0 ng/m3和0.4~5.1 ng/m3,冬季航次期间大气颗粒态PAHs含量的高值主要源于大陆气流对城市群大气PAHs污染的输送,另外干冷的季节亦有利于PAHs向颗粒态的富集.与此相反,气态多环芳烃含量的季节差异不明显.在冬季,随东北季风携带的城市粉尘可以将大气中的气态PAHs捕获,而春季航次的大气PAHs主要来源于西太平洋地区的远程输送和PAHs的海-气交换作用.认为受控于季风活动的水、热因子组合特征,是影响珠江口海域大气PAHs含量与分布的主导因素. 相似文献