Assessing benzene-induced toxicity on wild type Euglena gracilis Z and its mutant strain SMZ

Benzene is a representative member of volatile organic compounds and has been widely used as an industrial solvent. Groundwater contamination of benzene may pose risks to human health and ecosystems. Detection of benzene in the groundwater using chemical analysis is expensive and time consuming. In addition, biological responses to environmental exposures are uninformative using such analysis. Therefore, the aim of this study was to employ a microorganism, Euglena gracilis (E. gracilis) as a putative model to monitor the contamination of benzene in groundwater. To this end, we examined the wild type of E. gracilis Z and its mutant form, SMZ in their growth rate, morphology, chlorophyll content, formation of reactive oxygen species (ROS) and DNA damage in response to benzene exposure. The results showed that benzene inhibited cell growth in a dose response manner up to 48 h of exposure. SMZ showed a greater sensitivity compared to Z in response to benzene exposure. The difference was more evident at lower concentrations of benzene (0.005–5 μM) where growth inhibition occurred in SMZ but not in Z cells. We found that benzene induced morphological changes, formation of lipofuscin, and decreased chlorophyll content in Z strain in a dose response manner. No significant differences were found between the two strains in ROS formation and DNA damage by benzene at concentrations affecting cell growth. Based on these results, we conclude that E. gracilis cells were sensitive to benzene-induced toxicities for certain endpoints such as cell growth rate, morphological change, depletion of chlorophyll. Therefore, it is a potentially suitable model for monitoring the contamination of benzene and its effects in the groundwater.     

不同草皮构建的湖泊缓冲带对污染物的净化效果研究

选择宜兴地区常见的3种草皮百慕大(Cynodon dactylon)、白花三叶草(Trifolium repens)、高羊茅(Festuca arundinacea),利用自行设计的实验装置模拟构建草皮缓冲带,并模拟宜兴地区降雨时产生的汇流过程和雨量进行太湖缓冲带对陆域面源污染物的净化效果研究.结果表明,草皮缓冲带能有效地截留径流中的SS,3种草皮缓冲带的径流对SS的去除率为百慕大缓冲带＞三叶草缓冲带＞高羊茅缓冲带＞空白对照(不种植草皮的空白土壤),且沿程去除效果增强;草皮缓冲带的渗流对TN、NH3-N、TP净化效果均显著(p＜0.05)高于径流;3种草皮缓冲带在试验槽前0.9m处的污染物去除效果最为明显,湖泊缓冲带的宽度与其污染物截留效果呈正比;总体来说,草皮生物量与其构建的湖泊缓冲带的污染物去除率呈正相关,三叶草和百慕大有较大的地上生物量,其构建的缓冲带表现出较高的污染物去除率,而高羊茅的地上生物量相对较小,其构建的缓冲带污染物去除率也相对较低.     

Si对碳钢耐大气腐蚀性能影响的电化学研究

利用实验室周期浸润加速腐蚀试验来研究不同Si含量的试验钢的平均腐蚀速率.测定试验钢带锈试样的阳极极化曲线和交流阻抗谱,从失重和电化学角度来评价试验钢的耐腐蚀性能.结果表明,随着Si含量的增加,试验钢平均腐蚀速率增加,阳极极化电流增大,锈层电阻变小,试验钢锈层的保护能力变弱,说明Si的添加对试验钢耐工业大气腐蚀性能有恶化作用.     

SO2在碳钢初期大气腐蚀中的作用

通过自建的模拟大气腐蚀系统,借助金相显微镜、扫描电镜(SEM/EDX)、X-射线衍射(XRD)和x-射线光电子能谱(XPS),研究了SO2对碳钢初期大气腐蚀行为的影响,并进一步用原子力显微镜从更微观的角度观察了在SO2环境中初期阶段腐蚀形貌变化.研究结果表明:在SO2污染大气环境中,随SO2浓度的升高碳钢腐蚀加快.在体积分数为5×10(-6)SO2的大气环境中,碳钢和耐候钢表面腐蚀主要以条状物生长,随着SO2浓度的升高,腐蚀产物的形貌发生改变,在体积分数为5×10(-5)SO2的大气环境中,条状锈和胞状锈同时生长.在锈层中S元素以FeSO4·4H2O的形式存在,腐蚀产物中还有γ-FeOOH.SO2在初期阶段加速了碳钢的腐蚀,降低了碳钢的耐蚀性.     

生物质热电厂大气影响评价的研究

为确定生物质能发电环境方面的可行性,分析了生物质能发电的工艺流程,相比于火电的优缺点,并进行了生物质能热电联厂的大气环境影响评价研究。结果表明：预测评价的烟尘、SO2和NO2排放浓度分别为11,63mg／m^3、200．3mg／m^3和378．7mg／m^3,均远低于火力发电的排放值;在不同条件下、不同地点SO2和NO2的1小时、日均浓度也均远低于火力发电的浓度值。说明了生物质能发电在环境友好性方面具有明显的优势。     

20^#钢板镀铬在海洋环境条件下的腐蚀行为分析

本文根据20^#钢板镀铬材料在我国海洋环境的暴露结果,对20^#钢板镀铬材料在我国海洋环境条件下的腐蚀速度及腐蚀原因进行分析。     

基于社会保障功能的耕地保有量测算——以北京市房山区为例

在大城市郊区,社会保障体系还不完善,农民主要依靠土地来保障基本生活。因此,进行基于社会保障功能的耕地保有量的预测研究,对保障社会经济稳定、可持续发展有着重要的理论和现实意义。以北京市房山区为例,利用历年统计数据,从社会保障的角度上提出了耕地保有量测算方法,预测了耕地保有量,并将现状和上轮规划进行了比较。结论表明,北京市房山区非农建设占用耕地的速度趋于缓和,数量有所下降。     

Effects of rare earth elements on the distribution of mineral elements and heavy metals in horseradish

In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.     

人群疏散行为仿真技术研究

提出并建立了一种人群疏散仿真模型。针对疏散空间中障碍物的动态布局,采用网格法获得各障碍物包围盒坐标,依据最短路径原则采用几何法确定每个个体起始疏散路径,解决了人群疏散的空间连续性问题。针对人群疏散时个体之间的差异性,依据个体与个体之间的作用力、摩擦力动态改变个体的行进方向,以及依据人群密度采用人群疏散速度模型实时确定每个个体的运动速度,解决了个体之间的动态避碰、绕行和超越等问题。针对人群疏散时多个出口的选择问题,提出了把出口拥挤状态与个体心理慌乱状态相结合的出口选择方法。最后采用粒子系统实现了上述人群疏散行为的二维仿真并取得了较好的效果。     

发展和完善我国航空安全自愿报告系统的研究

鉴于当前我国航空安全自愿报告系统运行时间短、效果不佳的现状,主要从航空安全自愿报告系统运行、系统平台功能设计及信息处理分析3方面,对国内外大量航空安全自愿报告系统进行研究。指出目前我国航空安全自愿报告系统在系统设计、系统运行及后期的信息处理、信息发布利用等环节存在的问题和制约因素。就协调中立运行机构与系统3大原则之间的冲突,加强系统平台的人性化设计,提高信息分析处理效果,完善信息发布利用机制、提高信息利用度等关键问题给出了新的思路和对策。为我国航空自愿报告系统的完善和发展,提出了切实的改进建议和措施。