小球藻对Pb2+吸附及其亚细胞分布研究

通过溶液培养小球藻Pb2+暴露实验分析小球藻对Pb的富集以及亚细胞分布情况.结果表明:小球藻对Pb的富集总量随暴露浓度、暴露时间的增加而增加.运用差速离心法研究了小球藻中Pb在亚细胞中的分布,热力学实验与动力学实验的细胞分布结果均表明含细胞壁等残渣部分(组分I)中Pb的浓度远高于含细胞核、叶绿体、线粒体等细胞器膜系统(组分II)和可溶蛋白等细胞溶质部分(组分III)中Pb的浓度.采用动力学模型与等温线方程对实验数据进行拟合,结果表明小球藻对于Pb2+的生物吸附过程适宜用Elovich方程和二级吸附速率方程采描述,生物吸附平衡可用Langmiur等温式和Freundlich等温式来描述,小球藻对于Pb2+的生物吸附为非均相的扩散过程.     

Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying organisms, and enzyme activities in a rice-oilseed rape cropping system

DMPP （3,4-dimethylpyrazole phosphate） has been used to reduce nitrogen （N） loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N （NH4^＋- N and NO3^--N） leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone （UA）, urea ＋ 1% DMPP （DP）, and no fertilizer （CK）, have been carded out. The results showed that DP enhanced the mean NH4^＋-N concentrations by 19.1%-24.3%, but reduced the mean NO3^--N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO3^--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system.     

厦门市酸雨分布特征与气象条件的关系分析

厦门市是我国酸雨控制区之一。文章利用1992～2005年厦门市的探空、降水量和酸雨资料来分析厦门市不同气象条件对降水酸度、酸雨出现率的影响,分析结果表明:(1)不同等级的降水对降水酸度和酸雨出现率有明显影响,相对于夏、秋二季,冬、春二季的降水酸度更酸,酸雨出现率更高。(2)K指数、850～700hPa层的冷暖平流对酸雨污染没有明显影响。(3)酸雨出现率随着1500m高空风速的增大而增多,风向变化对降水酸度和酸雨出现机率的影响不大。(4)逆温对酸雨污染的有一定的影响。     

几种常用农药在菠菜中的残留动态研究

在露地栽培条件下,研究了氯氰菊酯、氰戊菊酯、毒死蜱和百菌清在菠菜生产中的残留降解动态.试验结果表明,不同农药在菠菜体内的降解速度有很大差异,其残留量随用药后时间的延长而减少.在推荐用量和加倍用量叶面喷洒处理条件下,毒死蜱的半衰期分别为3.95 d和4.61 d,氯氰菊酯的半衰期分别为5.03 d和5.88 d,氰戊菊酯的半衰期分别为5.26 d和7.22 d,百菌清的半衰期分别为2.63 d和3.39 d.在试验的4种农药中,氰戊菊酯的半衰期最长,百菌清的半衰期最短.因此,在菠菜生产中使用农药时,应充分考虑所用农药的半衰期,严格掌握安全间隔期,确保生产的菠菜达到无公害菠菜的质量标准要求.     

Degradation of MTBE and TBA by a new isolate from MTBE-contaminated soil

Methyl ten-butyl ether （MTBE）, a gasoline additive, possesses serious problems to the environmental health. In the present study, a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. The isolate was identified as Chryseobacterium sp., a new species capable of degrading MTBE. In order to enhance its degradation ability, selected environment factors were investigated. The results showed that the optimal temperature was in the range of 25-30℃, the pH was 7.0, the inoculum size was 2 × 10^8 CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L. The maximum MTBE utilization rate （Vmax） was 102 nmol MTBE/（mg cell protein.h）. Furthermore, it was found that the isolate could also degrade tert-butyl alcohol （TBA）. The degradation rates of TBA were much faster than those of MTBE. The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration. Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture.     

芦苇和香蒲对重金属钼的吸收特性研究

研究了水生植物芦苇和香蒲对重金属钼的吸收特性.通过短期室内水培实验,对比考察了2种植物对重金属钼的耐毒性、动态去除率、吸收过程及富集情况,并对在不同浓度营养液中植物对重金属钼吸收的影响进行了分析.结果表明,2种植物钼中毒导致其茎叶发黄、蒸腾能力下降,在钼浓度为2～20 mg.L-1时,香蒲对重金属钼的耐毒性较芦苇强.香蒲对重金属钼的去除率高于芦苇,在钼浓度为2 mg.L-1时,香蒲和芦苇去除率分别为87%和62%.2种植物对重金属钼的吸收是一个动态平衡过程,且以被动吸收为主.香蒲对钼的富集量较芦苇高,且植物地上部重金属积累量大于根部,符合超积累植物特征之一.营养液浓度的增加不会提高植物对重金属钼的吸收量,反而会因离子竞争等因素使去除率有所下降.芦苇和香蒲对溶液中钼的吸收均具有显著效果,香蒲吸收效果较芦苇好.     

AGILENT分光光度计化学工作站的故障维护

由美国Agilent 8453紫外-可见分光光度计和化学工作站构成的检测系统,人机监控介面良好,可以准确测量未知样浓度[1]。在某次检测过程中,化学工作站主机意外故障,维护后恢复正常使用。文章叙述并总结了维护要点。     

氮形态对人工湿地氮去除效果的影响

采用水平潜流人工湿地处理TN质量浓度为20～25 mgL,氮形态分别以NH4+-N,NO3--N和有机氮为主的生活污水,分析了氮形态时人工湿地N去除效果的影响.试验结果显示:相应的TN去除率分别为47.2%,71.6%和33.1%.表明人工湿地主要适用于水的深度处理,实现污水中N的无机化特别是将N转化为NO3--N,可显著提高人工湿地的N去除效果.     

测定水中总氮的消解方法

废水中总氮测定的预处理一般采用经典的压力蒸汽灭菌器消解,其缺点是消解时间较长、操作较为繁锁。经多次试验并查阅了相关资料,可以用COD消解仪、电热恒温干燥箱和微波炉代替压力蒸汽灭菌器进行消解。在保证测量准确性和精度的前提下,可以节约时间、简化操作步骤,提高工作效率。     

河南省典型炭素企业VOCs排放特征及臭氧生成潜势分析

挥发性有机物（VOCs）是主要的臭氧前体物之一,控制VOCs排放是打赢“蓝天保卫战”的重要组成部分.研究工业源VOCs排放特征和对O₃生成贡献对制定和修订相关VOCs排放标准、有针对性控制VOCs排放具有重要意义.炭素行业是非金属制品业的重要组成部分,属于高污染行业,对该行业有组织VOCs排放的研究鲜见文献报道.本文选取河南省某典型炭素企业Y炭素厂作为研究对象,通过实地采样分析了不同工序有组织和车间内、外无组织117种VOCs排放特征,计算臭氧生成潜势（OFP）并评估了不同VOCs类别和物种对O₃生成的贡献.研究表明,Y炭素厂排放因子为0.031 g·kg^-1,其中焙烧工序有组织VOCs排放量最大.总有组织排放占比较大的VOCs类别有烯烃（23.56%）、烷烃（21.24%）、芳香烃（18.17%）、卤代烃（15.34%）和含氧化合物（8.95%）等,占比较大的VOCs物种有乙烯（18.2%）、乙烷（11.5%）、苯（8.66%）和 乙炔（7.15%）等.车间内无组织排放占比较大的VOCs物种则为萘和四氯化碳等.总有组织排放的VOCs中,烯烃、芳香烃和含氧化合物的OFP占比较大,分别为71.72%、11.35%、10.05%,其中乙烯、丙烯的OFP占比分别为52.91%和13.98%,是需要重点治理的O₃生成前体物.