向家坝库区沉积物磷形态分布及释放风险

采用改进的连续提取法研究了向家坝库区沉积物中有机磷（OP）和无机磷（IP）的各赋存形态及分布特征,讨论了各形态磷的生物可利用性和释放风险.结果表明,向家坝库区沉积物总磷（TP）含量为388.9~616.4 mg·kg^-1,总体处于安全级别.库区沉积物磷形态以惰性碎屑态无机磷（De-P_i）和残渣态有机磷（Re-P_o）为主,两者共占TP质量分数的60%以上,呈上游高下游低的趋势,流域地质背景是主要的影响因素.以可交换态无机磷（Ex-P_i）、铝结合态无机磷（Al-P_i）、铁结合态无机磷（Fe-P_i）、可交换态有机磷（Ex-P_o）、铁铝结合态有机磷（Fe/Al-P_o）之和来估算生物可利用磷（BAP）,BAP/TP来评价沉积物中磷的释放风险,BAP含量为23.0~91.1 mg·kg^-1,BAP/TP为6.2%~17.1%.向家坝水库沉积物磷的释放风险较低.库区沉积物BAP储量为767.68 t,对向家坝水库上覆水磷浓度的潜在贡献为0.148 mg·L^-1,是导致未来库区水质恶化的重要因素 之一,应加强对库区内源磷的释放管理.     

高速铁路车轮减振降噪优化方法

高速铁路车轮的振动辐射噪声在轮轨滚动辐射噪声中占有很大的比重,而且在1500Hz以上的频段内占主导,对列车车轮进行优化设计,通过改变车轮的形状,可以达到较好的减振降噪效果。本文对高速铁路车轮优化方法进行详细的分析评论,并提出相应的问题和改进的方向。     

紫外吸收剂在湖泊中的分布及其对底栖动物的毒性效应

紫外吸收剂大量用于工业材料和个人护理品中,近年来在水体中不断被检出,同时由于其高度亲脂性,易在底泥和水生生物体内富集,产生潜在的毒性效应,已成为一类新型污染物。本文综述了紫外吸收剂在湖泊环境中的分布和生物富集效应,重点分析了二苯甲酮类等典型紫外吸收剂对底栖动物的药物代谢系统、抗氧化系统及其生长发育的影响及其毒性作用机制,并对未来该领域的研究进行了展望。     

Magnetic graphene-based nanocomposites as highly efficient absorbents for Cr(VI) removal from wastewater

Environmental Science and Pollution Research - Due to the merits of their high adsorption and convenient separation, magnetic graphene-based composites have become a promising adsorbent in terms of...     

Carbonaceous and nitrogenous disinfection byproduct precursor variation during the reversed anaerobic–anoxic–oxic process of a sewage treatment plant

Disinfection byproduct(DBP)precursors in wastewater during the reversed anaerobic–anoxic–oxic(A~2/O)process,as well as their molecular weight(MW)and polarity-based fractions,were characterized with UV scanning,fluorescence excitation emission matrix,Fourier transform infrared and nuclear magnetic resonance spectroscopy.Their DBP formation potentials(DBPFPs)after chlorination were further tested.Results indicated that the reversed A~2/O process could not only effectively remove the dissolved organic carbon(DOC)and dissolved total nitrogen in the wastewater,but also affect the MW distribution and hydrophilic–hydrophobic properties of dissolved organic matter(DOM).The accumulation of low MW and hydrophobic(HPO)DOM was possibly due to the formation of soluble microbial product-like(SMP-like)matters in the reversed A~2/O treatment,especially in the anoxic and aerobic processes.Moreover,DOM in the wastewater displayed a high carbonaceous disinfection byproduct formation potential(C-DBPFP)in the fractions of MW100 k Da and MW5 k Da,and revealed an increasing tendency of nitrogenous disinfection byproduct formation potential(N-DBPFP)with decrease of MW.For polarity-based fractions,the HPO fraction of wastewater showed significantly higher C-DBPFP and N-DBPFP than hydrophilic and transphilic fractions.Therefore,although the reversed A~2/O process could remove most DBP precursors by DOC reduction,it led to the enhancement of DBPFP with the formation and accumulation of low MW and HPO DOM.In addition,strong correlations between C-DBPFPs and SUVA,and between N-DBPFPs and DON/DOC,were observed in the wastewater,which might be helpful for DBPFP prediction in wastewater and reclaimed water chlorination.     

Some extensions on risk matrix approach

This paper introduces the basic concepts of risk as the research background and reviews a widely applied semi-quantitative tool for risk assessment, namely risk matrix approach (RMA) as well as its typical variations. Based on the deep analysis of the essence and defects of RMA, some extensions on risk matrix approach are presented and their superiorities compared with the related quondam methods are demonstrated by a case study. The features and advantages of the new extensions are discussed and the prospects of the future study are addressed.     

正丁醇对柴油机颗粒组分与形貌特征的影响

为探讨柴油机燃用正丁醇-柴油混合燃料降低颗粒排放的机理,采用热重分析仪与场发射扫描电子显微镜,重点对正丁醇-柴油混合燃料燃烧的颗粒形貌特征进行研究,分析了颗粒的组分、微观结构以及粒径分布随w(正丁醇)的变化规律. 结果表明:正丁醇-柴油混合燃料燃烧的颗粒呈团簇状结构,随着w(正丁醇)的增加,团聚程度逐渐提高,排列结构更加紧密;颗粒的粒径逐渐减小,柴油、B5、B10〔B5、B10是指w(正丁醇)分别为5%、10%的正丁醇-柴油混合燃料〕燃烧的颗粒平均粒径分别为1.43、0.85、0.52 μm;颗粒中的主要成分为碳烟,其质量分数约为60%,随着w(正丁醇)的增加,碳烟和可溶有机物组分的质量分数有所增加,硫酸盐、金属等不易挥发组分以及金属元素的质量分数逐渐减少. 研究显示,添加正丁醇,可促进颗粒转化、改善颗粒的氧化过程,使颗粒向小粒径方向移动;由于颗粒中可溶有机物组分含量增加,因此提高了颗粒在碰撞过程中凝并的概率,致使颗粒的团聚程度增加.      

磁载纳米TiO2复合光催化材料的研究进展

磁载纳米TiO2复合光催化剂是一种无污染,制备成本低,催化活性高,在外加磁场下可迅速分离回收和重复使用的光催化材料,在废水的光催化降解中有着诱人的应用前景.本文综述了不同类型磁载纳米TiO2复合光催化材料的制备方法和光催化性能,总结了其在染料、农药、芳香烃及其衍生物、有害无机离子和有毒气体等各种环境污染物处理中的应用,并展望了磁载纳米TiO2复合光催化剂的发展方向.     

辽河表层沉积物重金属生态风险与综合毒性表征

采用ICP-MS测定了辽河26个支流表层沉积物间隙水中7种重金属(Pb、Cu、Cr、Zn、Ni、As、Cd)的含量,并应用间隙水毒性基准单位(IWCTU)和Nemeraw指数(NI)对间隙水重金属生态风险进行了评价;同时利用摇蚊幼虫活体生物毒性测试方法评估了辽河流域26个支流表层沉积物的综合毒性。研究结果显示,辽河支流表层沉积物间隙水7种重金属平均含量为:Pb 3.92μg·L-1,Cu 5.73μg·L-1,Cr 7.21μg·L-1,Zn 4.33μg·L-1,Ni 4.48μg·L-1,As 5.89μg·L-1,Cd 0.29μg·L-1,根据IWCTU值和NI值,柴河、养息牧、亮子河、凡河、付家窝堡、接官厅具有潜在的生态风险;综合毒性表征结果表明,柴河、长沟子河、付家窝堡、柳河、一统河、潮沟河表层沉积物对摇蚊幼虫具有较高毒性。结合重金属毒性和综合毒性分析,认为辽河流域支流表层沉积物毒性应该是由复合污染形成,而不仅仅是重金属污染。     

浅谈大学生诚信教育

诚实守信是中华民族的传统美德,是做人的基本道德标准之一。然而,在市场经济的影响下,在社会处于转轨时期的历史条件下,大学生诚信却存在着不少不尽如人意的地方,其产生原因主要是社会环境、学校教育以及家庭教育之间存在着缺失。鉴于此,应从课堂、教师、校园、社会、法制等方面入手,制造诚信氛围,加强大学生的诚信教育。