上甸子区域本底站大气痕量活性气体的变化规律

利用TE公司C系列气体监测仪,于2005年1月1日-12月31日,在北京上甸子区域大气本底站连续观测SO2,CO,NO-NO2-NOx和O3的浓度.分析了晴天、雨天、霾天和沙尘天气条件下,不同气体的变化特征及影响因素.结果表明:(1)痕量活性气体在不同天气条件下具有不同的浓度及日变化特征,晴天和雨天日变化最小,而霾天日变化最大;(2)风向和风速是影响上甸子气体浓度变化的重要因素,同时,夏季降水对SO2和NOx的去除作用较为明显;(3)上甸子O3白天最大值与夜间最小值的比值低于4,远低于城区,不利于光化学污染的形成.     

生物栅净化系统生物膜微生物群落结构动态的ERIC-PCR指纹图谱分析

用ERIC-PCR指纹图谱技术分析富营养化水体生物栅处理系统中2个工况7个净化池在不同监测时期微生物群落结构动态变化与主要污染物降解效果变化的关系.结果表明,采用生物栅技术的2～7号净化池的CODCr、总氮、氨氮、总磷的去除率较对照池分别提高了13.3%～58.6%、23.6%～65.8%、15.5%～72.9%和16.8%～76.9%,表明生物栅技术在污染物去除方面起到了重要作用.随着系统的运行微生物多样性指数逐渐增大,工况1第1次和第2次生物膜样品的微生物多样性指数分别为1.77～1.91和1.96～2.35.设置凤眼莲的3个净化池填料生物膜微生物种类较未设置植物的净化池丰富.在工况2中,HRT为7.5h的3号、5号和7号反应池填料生物膜ERIC-PCR指纹图条带数比HRT为4h的2号、4号和6号要多,而根系生物膜上的微生物群落结构受HRT的影响小.研究表明,随着系统的运行,系统中微生物种群多样性指数增加,系统逐渐进入良好的稳定状态.图5表5参9     

慢生根瘤菌交叉结瘤及其系统发育关系的研究

选用包括6株花往根瘤菌[Bradyrhizobium sp.(Arachis)]在内的13株慢生根瘤菌，进行了6种豆科植物结瘤试验及共系统发育分析。研究结果表明，慢生根瘤菌与试验的豆科宿主植物间普遍存在交叉结瘤，还发现有些菌株在原宿主外的豆科植物根部形成类根瘤的现象。16S rDNA和23S rDNA的PCR－RFLP分析揭示出这些菌株rDNA基因的差异性，不同宿主来源的慢生根瘤菌株可以同属一个rDNA类型，而从同一宿主中分离的根瘤菌菌株可分属多种不同的rDNA类型，研究结果表明，采用rDNA PCR-RFLP等遗传背景分析的手段，可能筛选出广谱的根瘤菌力株，表4参8。     

有机化学品生物富集因子定量结构-活性关系模型

依据经济合作与发展组织(OECD)关于定量结构-活性关系(QSAR)模型构建和使用导则,将780个有机化合物,以4:1的比例随机划分为训练集(624个化合物)和验证集(156个化合物),通过多元线性回归(MLR)方法构建了一个包含12个描述符的有机化合物鱼类生物富集因子(BCF)的QSAR模型。QSAR模型的调整决定系数R2ad j=0.809,去一法交叉验证系数Q2LOO=0.803,外部验证系数Q2EXT=0.732,表明模型具有较好的拟合优度、稳健性和预测能力。采用欧几里德距离方法表征模型应用域,通过威廉姆斯图分析模型离群点,并对模型进行机理解释。所构建的模型,可以用于预测应用域内有机化学品的生物富集因子。     

Factors affecting simultaneous nitrification and denitrification in an SBBR treating domestic wastewater

An aerobic sequencing batch biofilm reactor (SBBR) packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification. The SBBR is advantageous for creating an anoxic condition, and the biofilm can absorb and store carbon for good nitrification and denitrification. An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification. Volumetric loads of TN dropped dramatically and effluent TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L. The efficiency of simultaneous nitrification and denitrification (SND) increased with increasing thickness of the biofilm. The influent concentration hardly affected the TN removal efficiency, but the effluent TN increased with increasing influent concentration. It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements. At optimum operating parameters, the TN removal efficiency of 74%–82% could be achieved.     

趋磁细菌的分子生物学研究进展

趋磁细菌菌体内含有磁小体,能够沿地球磁力线方向定位、运动.趋磁细菌和磁小体的研究具有重要的理论意义和应用价值.本文对趋磁细菌及其胞内产物磁小体作了介绍,论述了该领域分子生物学方面的研究进展,包括与磁小体相关的基因和蛋白的研究、趋磁细菌遗传体系及基因组方面的研究等,展望了该领域今后的发展前景.图3表1参35     

天津地区鱼塘水、悬浮物、沉积物和鱼体中的DDT

采样测定了天津地区2典型鱼塘鲫鱼、鲢鱼、水、悬浮物、沉积物和鱼塘周边表土中的DDT及其代谢产物含量。结果发现,2鱼塘各主要介质以及鱼体肌肉和器官中都富集了较高浓度的DDT。鲫鱼和鲢鱼肌肉中DDT的含量分别为(66.4±2.7)ng·g-1和(24.3±23.4)ng·g-1。肝胰脏、肠和鱼鳃中DDT含量一般高于肌肉,其中肠的富集量最大,是肌肉的3倍以上。生物富集系数(lgBCF)分别为3.7和3.3。2鱼塘鱼体和各相含量有较大差别,鱼塘介质中悬浮物富集浓度最高。表土污染相对严重地区的鱼塘中各介质和鱼体DDT含量均高于另一污染较轻的鱼塘。污染严重鱼塘的DDE/ΣDDT含量比值也相对较高,反映早期污染残留的重要特征。尽管如此,仍然较高的DDT含量以及悬浮物中很低的DDE/ΣDDT含量比值说明很可能还有污染源存在。     

A nonparametric procedure for analyzing repeated measures of spatially correlated data

Many agricultural, biological, and environmental studies involve detecting temporal changes of a response variable, based on data observed at sampling sites in a spatial region and repeatedly over several time points. That is, data are repeated measures over time and are potentially correlated across space. The traditional repeated-measures analysis allows for time dependence but assumes that the observations at different sampling sites are mutually independent, which may not be suitable for field data that are correlated across space. In this paper, a nonparametric large-sample inference procedure is developed to assess the time effects while accounting for the spatial dependence using a block bootstrap. For illustration, the methodology is applied to describe the population changes of root-lesion nematodes over time in a production field in Wisconsin.     

Impact of photosynthesis and transpiration on nitrogen removal in constructed wetlands

To determine the impact of photosynthesis and transpiration on nitrogen removal in wetlands, an artificial wetland planted with reeds was constructed to treat highly concentrated domestic wastewater. Under different meteorological and hydraulic conditions, the daily changes of photosynthesis and transpiration of reeds, as well as nitrogen removal efficiency were measured. It was found that net photosynthesis rate per unit leaf area was maintained on a high level (average 19.0 μmol CO₂/(m²·s)) from 10:00 to 14:00 in July 2004 and reached a peak of 21.1 μmol CO₂/(m²·s) when Photon Flux Density was high during the day. Meanwhile, TN and NH₄ ⁺-N removal efficiency rose to 79.6% and 89.6%, respectively—the maximum values observed in the test. Correlation coefficient analysis demonstrated a positive correlation among photon flux density, net photosynthetic rate, transpiration rate, and TN and NH₄ ⁺-N removal efficiency. In contrast, there was a negative correlation between stomatal conductance and TN and NH₄ ⁺-N removal efficiency. Results suggest that the photosynthesis and transpiration of wetland plants have a great impact on nitrogen removal efficiency of wetlands, which can be enhanced by an increase in the photosynthesis and transpiration rate. In addition, the efficiency of water usage by reeds and nitrogen removal efficiency could be affected by the water level in wetlands; a higher level boosts nitrogen removal efficiency.     

星湖沉积物特性研究

以肇庆星湖为研究对象，研究了其沉积物的各种特性。研究表明：(1)星湖沉积物的矿相(晶体物)主要为石英、伊利石、长石、绿泥石等；(2)沉积物中的TP、TN含量，基本随湖水交换和季节变化而变化，与交换量有着简单反比关系，其TP的含量在0．03％～0．06％之间，TN在0．19％～0．28％之间，内负荷较为严重；(3)沉积物的沉降存在很大的不均衡性；(4)沉积物营养物的释放受环境因子影响，其中溶解氧对N、P的释放都有较大的影响，温度对P的影响较N多一些，而保持水体中性，则有利于水体的稳定。