石油污染土壤原位生物修复的强化实验研究

为研究添加营养物质和高效降解石油微生物对油污土壤生物修复的作用,通过分层土柱的方法,连续监测了不同条件下不同土层的含水率、石油烃含量、细菌数量及脱氢酶活性。结果表明:添加营养物质同时接种高效微生物可使降解效果明显改善,降解率比在自然条件下提高近50%,而单纯添加营养物质不接种高效微生物可使降解率比在自然条件下提高约25%。降解初期,上层土壤降解效果较好,而到中后期,中下层降解效果好于上层。微生物数量和脱氢酶活性与石油降解率之间存在良好的相关性,脱氢酶活性比微生物数量更能反映修复过程中微生物的存活状态。添加营养物质和高效降解石油微生物对油污土壤原位生物修复具有强化作用。     

基于力学机制的钢筋混凝土柱抗剪承载力模型∗

为了兼顾钢筋混凝土(RC)柱抗剪承载力分析的计算精度和简便性,研究建立了一种基于力学机制的RC柱抗剪承载力简化模型。首先基于变角桁架-拱模型理论,结合变角桁架模型的力平衡条件以及变角桁架模型和拱模型之间的变形协调条件,建立了RC柱抗剪承载力分析的理论模型;然后利用38组试验数据进行统计分析,分别确定了混凝土、箍筋和拱模型的抗剪承载力贡献系数近似取值,在此基础上建立了R C柱抗剪承载力分析的简化模型;最后通过与试验数据进行对比分析,验证了该模型的计算精度和适用性。分析结果表明,该模型不仅可以合理分析混凝土、箍筋和拱作用的抗剪承载力贡献,具有较高的计算精度,而且计算公式较为简洁。     

Wet and dry epoch durations of spatially averaged rain rate,their probability distributions and scaling properties

This article is concerned with the notion of duration of wet and dry epochs in stochastic processes of spatially averaged (instantaneous) rain rate over a given region. Gamma, Lognormal, and Inverse Gaussian parametric families of probability distributions have been considered as candidate models for the distribution of such durations. Goodness of these model's fit to data of dry and wet epoch durations obtained from real time series of spatially averaged rain rate, has been tested with Pearson's -test. The parameters of each of these models have been estimated by maximum likelihood and method of moments, based on TOGA-COARE measurements of tropical rainfall. The hypotheses of independence and identical distribution (i.i.d.) among durations of dry or wet epochs have also been tested using a certain version of the Wald-Wolfowitz test. Finally, the effect of spatial scale on the moments of dry and wet epoch durations has also been investigated, pointing to self-similarity of the underlying random structures over space. The main result of this study is that among the three candidate models, Inverse Gaussian is the one conforming most adequately with all the classical testing criteria implemented here, and also with the newly established scaling behavior of both dry and wet epoch duration processes over space. This is a remarkable finding, considering that the Inverse Gaussian family has recently been also justified from a theoretical viewpoint as a reasonable model for the probability distributions of dry and wet epoch durations.     

立柱和柱式无土栽培系统及其在生菜栽培上的应用

具溢水管 ,容积为 1L的 12只ABS塑料盆钵组装的水培立柱 ,其底部是底座 ,顶部是淋滴装置 ,总高 2 0 0cm ,直径为 15cm .按柱间距 80cm× 80cm排列在面积有A =5 40m2 的非自控玻璃温室内 ,然后再串联和并联成”树林”式栽培整体 .该整体含 6 36根立柱 ,每根立柱的最多种植量有 6 0株 ,总共种植 3816 0株 ,加地面原有种植数 10 314株 ,共有 48474株 ,此为地面原种植量的 4.7倍 .立柱被安装在地面水槽上 ,通过循环灌溉系统 (营养液 )将立柱无土栽培和地面无土栽培组合为一体 ,即谓柱式无土栽培系统 .柱式无土栽培系统全种生菜 ,育苗移栽 ,种后 40d(中后期 ) ,立柱区的光照E =6 80～ 86 0 μEm- 2 s- 1 ,高出生菜光合作用饱和点E =180～ 36 0 μEm- 2 s- 1 .立柱上的小栽培钵的一点底面接触水面 ,使苗的大部分根数生长于水面之上湿润的岩棉之中 ,良好的生长空间加上流动的水柱 ,生菜获得了水、气、肥协调的根部环境 .冬季最高气温平均为θ =2 0℃ ,最低气温平均有θ =3.3℃ ,RH =5 7%～ 71% .种后 5 3d(生长后期 ) ,生菜产量平均有 5 .6kg /m2 ,较CK(平均 1.5kg /m2 )提高 3.7倍 .柱式无土栽培系统是一种高产高效的工厂化生产模式 .图 7表 3参 7     

楼板对钢筋混凝土框架结构受力性能影响

汶川8级地震震害调查发现,这次地震中现浇钢筋混凝土框架结构多发生"强梁弱柱"型破坏,这与规范中"强柱弱梁"抗震设计原则相悖。为探究其原因,采用ABAQUS软件对钢筋混凝土带楼板框架和空框架结构进行了侧向加载情况的性能分析。通过对比纵向梁端钢筋应力变化和柱端钢筋应力变化,以及分析不同侧向位移对应的楼板钢筋的应力变化情况,指出楼板对梁端抗负弯矩能力的增强有很大贡献。研究了节点类型、楼板钢筋材性、侧向位移、梁高、梁跨和板厚等因素对纵向梁端处楼板有效宽度的影响规律,提出了负弯矩作用下梁端处楼板有效宽度的取值方法。     

取代苯乙酮类有机物溶解度和分配系数的测定

本文采用产生柱法测定取代苯乙酮类有机物的水溶解度和正辛醇-水分配系数,与静态法和振荡法测定的水溶解度、摇瓶法测定的正辛醇-水分配系数相比较,证明此方法是可行的,并和分子连接性指数呈良好的相关性。     

生物炭负载硫化改性纳米零价铁去除水中的Cr(Ⅵ)

为研发治理地下水Cr(Ⅵ)污染的可行除铬材料,以碳热法制得生物炭负载纳米零价铁（BC-nZVI）,并通过对BC-nZVI硫化改性制备得到改性材料（M-BC-nZVI）,采用除铬容量、铬铁比（Cr/Fe）、反应活性分析M-BC-nZVI的除铬优势,通过模拟柱试验建立失效速率模型,从而推算M-BC-nZVI完全失效的除铬容量,最后与相关文献数据进行对比,分析M-BC-nZVI除Cr(Ⅵ)的应用可行性。结果表明：M-BC-nZVI材料的除铬容量、Cr/Fe、拟一级反应速率常数（k_obs）分别是BC-nZVI的1.86倍、1.95倍和3.00倍,因此相对于BC-nZVI来说M-BC-nZVI更具除铬优势;各模拟柱在运行过程中无明显堵塞情况,且随着进水浓度的升高,M-BC-nZVI的失效速率常数变大。当失效除铬速率为初始除铬速率的1.0%、进水Cr(Ⅵ)浓度为5 mg/L时,除铬容量最高,可以达到12.70 mg/g;对比M-BC-nZVI与其他文献报道的铁基材料及铁基改性材料的Cr/Fe可知,M-BC-nZVI的Cr/Fe为其他文献的1.06~42.06倍,故从材料的除铬性能来看,M-BC-nZVI应用于可渗透反应墙处理地下水Cr(Ⅵ)污染可行。

     

硅胶分离-气相色谱法测定海水样品中的有机氯农药及多氯联苯

建立了硅胶净化-具电子捕获检测器气相色谱(GC-ECD)测定海水样品中有机氯农药(OCPs)、多氯联苯(PCBs)的方法。海水样品经正己烷萃取,浓缩萃取液后过硅胶层析柱,通过梯度淋洗进行样品的净化和分离,采用GC-ECD进行分析测试。OCPs回收率达70.7%~109.2%,PCBs回收率达92.6%~119.2%。采用GC-MS进行辅助确证,结果表明,方法可行。     

不同状态样品培养下太湖地区黄泥土好气呼吸与CO2产生潜力

土壤呼吸的CO2释放是陆地生态系统快速而活跃的土气交换途径,培养试验常用来讨论土壤的有机碳矿化及其温室气体产生潜力.对太湖地区一个代表性水稻土在水稻收割后采集土壤, 分别进行常规(磨碎土的培养瓶法)和原状土恒温好气培养,测定分析土壤呼吸的CO2释放量,讨论其有机碳矿化与CO2释放潜力.结果表明,该水稻土常规培养CO2呼吸释放速率在CO2-C 12.85 ～ 15.17 mg·kg-1·d-1范围, 而原状土培养CO2呼吸释放速率在CO2-C 2.15 ～ 4.47 mg·kg-1·d-1范围,虽然两者均显著低于文献报道的培养研究结果,但原状土培养下土壤呼吸及CO2产生潜力看起来较大幅度地低于磨碎土常规培养结果,前者与同地区田间监测结果计算的值相当.不但如此,培养中土壤呼吸作用与CO2释放动态格式也发生变化,原状土条件下存在一个较为稳定的低呼吸速率阶段,不同施肥处理下这一阶段的差异十分明显.计算表明,原状土培养下存在微生物潜在可矿化碳的土壤保护作用,这种保护性碳约占土壤有机碳总量的2%左右,较大于Pulleman & Marinissen (2004) 对于草地土壤团聚体有机碳矿化的研究结果.采用磨碎样品的常规培养实验可能会高估水稻土有机碳矿化与CO2释放潜力.     

Fate of atrazine in a soil under different agronomic management practices

Agricultural management affects the movement of atrazine in soil and leaching to groundwater. The objective of this study was to determine atrazine adsorption in a soil after 20 years of atrazine application under agronomic management practices differing in tillage practice (conventional and zero tillage), residue management (with and without residue retention) and crop rotation (wheat-maize rotation and maize monoculture). Atrazine sorption was determined using batch and column experiments. In the batch experiment, the highest distribution coefficient K_d (1.1 L kg^?1) at 0–10 cm soil depth was observed under zero tillage, crop rotation and residue retention (conservation agriculture). The key factor in adsorption was soil organic matter content and type. This was confirmed in the column experiment, in which the highest K_d values were observed in treatments with residue retention, under either zero or conventional tillage (0.81 and 0.68 L kg^?1, respectively). Under zero tillage, the fact that there was no soil movement helped to increase the K_d. The increased soil organic matter content with conservation agriculture may be more important than preferential flow due to higher pore connectivity in the same system. The soil's capacity to adsorb 2-hydroxyatrazine (HA), an important atrazine metabolite, was more important than its capacity to adsorb atrazine, and was similar under all four management practices (K_d ranged from 30 to 40 L kg^?1). The HA adsorption was attributed to the type and amount of clay in the soil, which is unaffected by agronomic management. Soils under conservation agriculture had higher atrazine retention potential than soils under conventional tillage, the system that predominates in the study area.