苯酚、菲在BS-12/DTAB复配修饰膨润土上吸附的差异

为了探究复配修饰膨润土吸附疏水性不同的污染物的差异,采用阳离子型表面修饰剂十二烷基三甲基溴化铵(DTAB)对两性表面修饰剂十二烷基二甲基甜菜碱(BS-12)修饰膨润土进行复配修饰,采用批处理法研究复配修饰膨润土总修饰比例对苯酚和菲的等温吸附影响,并对比不同温度、pH值和离子强度条件下供试土样对苯酚和菲吸附量、热力学参数的差异.结果表明:随着总修饰比例的增大,复配修饰膨润土对苯酚及菲的吸附能力逐渐增强,0~50%CEC修饰比例下,菲的吸附率大于苯酚的吸附率,当修饰比例超出50%CEC后,苯酚的吸附率大于菲的吸附率,总修饰比例超出150%CEC后,膨润土对苯酚的吸附率变化趋于平缓,而对菲的吸附率开始呈下降趋势;随着土样总修饰比例的增大,温度对苯酚及菲吸附量的抑制效果降低;在KNO_3浓度为0.001~0.1 mol·L~(-1)时,苯酚及菲的吸附量均随着KNO_3浓度的增大而增大;随着pH值的升高,苯酚的吸附量逐渐增大,在pH=7处达到最大,而菲的吸附量则始终呈降低趋势.热力学参数显示,随着总修饰比例的增大,复配修饰土样对苯酚和菲的吸附自发性增强,混乱度增大,当总修饰比例超出150%CEC后,自发性减弱,混乱度下降.     

菲和镉单一及复合污染条件下在毛蚶体内的富集动力学研究

采用室内半静态双箱动力学模型实验,研究了菲和镉单一及复合污染条件下在毛蚶(Anadara subcrenata)体内的生物富集,通过对富集与释放过程中毛蚶体内菲和Cd的富集量进行非线性曲线拟合,获得了菲和Cd单一及复合污染条件下在毛蚶体内的吸收速率常数k1、释放速率常数k2、生物富集因子BCF、生物半衰期B1/2和平衡状态下最大富集量CA max等动力学参数。实验结果表明,菲和Cd在实验前期富集速率较高,8 d以后富集速率减缓,释放阶段与富集阶段相似。毛蚶对菲的BCF值为37.80,远大于Cd的BCF值13.12,且生物半衰期时间更长,菲更容易在生物体内富集。菲和Cd联合暴露条件下,在毛蚶体内的CA max和BCF值均大于单一作用,说明二者同时暴露时,毛蚶对菲和镉的吸收富集均有所增强。实验模型拟合度较好,输出值和实测值之间无显著性差异,拟合方程和拟合参数可信。     

植物根系质外体溶液的提取方法研究:以多环芳烃为例

根系质外体溶液中多环芳烃(PAHs)的分析对于阐明植物根系PAHs吸收运移机制及阻控意义重大.然而,迄今鲜有便捷成熟的植物根系质外体溶液提取方法的报道.为此,本研究以小麦为材料,菲为PAHs的代表,探究了植物根系质外体溶液的真空渗透离心提取方法.结果表明,小麦根系质外体菲提取量随真空度、真空时间、离心速率、离心时间的增加而增大;小麦根系质外体六磷酸葡萄糖脱氢酶(G6PDH)活性随真空度、真空时间、离心速率、离心时间的增加而升高.依据质外体溶液受原生质污染程度小于1%且尽量提取完全的原则,真空渗透离心提取法的最佳真空度为70 k Pa,最佳真空时间为10 min,最佳离心速率为3 068 r·min-1,最佳离心时间为15 min.研究结果可为污染物的植物根系质外体运输研究提供有效、简便的方法支撑.     

采用固定化技术处理土壤中菲、芘污染物

采用动胶杆菌(Zoogloea sp.)固定化技术包埋来降解土壤中菲、芘污染物,在不同接种量、不同系列浓度下,对降解效果进行了测定.结果表明:5%的接种量最为合理,在168h时,固定化细菌对菲、芘的降解率达84.89%和76.94%;而在相同条件下土著菌降解仅达到27.85%和19.65%,因此动胶杆菌(Zoogloea sp.)具有更好的降解能力.另外,还用电镜观察研究了动胶杆菌在载体中的分布形态,表明了固定化细菌降解土壤中菲、芘具有较高的优势.     

A Biosurfactant-Enhanced Soil Flushing for the Removal of Phenanthrene and Diesel in Sand

In order to examine the potential of biosurfactants in soil remediation, and to investigate the effects of several operating conditions, such as flow rate, biosurfactant concentration and surfactant type, biosurfactant-enhanced soil flushing was conducted. In the biosurfactant-enhanced soil flushing process, the removal efficiency increased as the flow rate decreased. Rhamnolipid showed no effect on the removal efficiency of phenanthrene and diesel from sand in the concentration range 0.3-0.5%. However, rhamnolipid showed higher efficiencies for the removal of phenanthrene and diesel from sand than Tween 80. Based on total recovery, following an equivalent pore volume flush, it was more difficult to remove diesel than phenanthrene. In order to obtain the specific removal efficiency, more pore volumes of surfactant solution may be required in field applications. Under optimum conditions, the biosurfactant removed as much as 70% of the phenanthrene and 60% of the diesel in the sand. These results indicate that the use of biosurfactants in the flushing process is favorable, not only with respect to the environment, but also on removal efficiencies.     

Uptake and accumulation of phenanthrene and pyrene in spiked soils by Ryegrass(Lolium perenne L.)

Phytoremediation has long been recognized as a cost-effective method for the removal of polycyclic aromatic hydrocarbons （PAHs） from soil. A study was conducted to investigate the uptake and accumulation of PAHs in root and shoot of Lolium perenne L. Pot experiments were conducted with series of concentrations of 3.31-378.37 mg/kg for phenanthrene and those of 4.22-365.38 mg/kg for pyrene in a greenhouse. The results showed that both ryegrass roots and shoots did take up PAHs from spiked soils, and generally increased with increasing concentrations of PAH in soil. Bioconcentration factors（BCFs） of phenanthrene by shoots and roots were 0.24- 4.25 and 0.17-2.12 for the same treatment. BCFs of pyrene by shoots were 0.20-1.5, except for 4.06 in 4.32 mg/kg treatment, much lower than BCFs of pyrene by roots （0.58-2.28）. BCFs of phenanthrene and pyrene tended to decrease with increasing concentrations of phenanthrene and pyrene in soil. Direct uptake and accumulation of these compounds by Lolium perenne L. was very low compared with the other loss pathways, which meant that plant-promoted microbial biodegradation might be the main contribution to plant-enhanced removal of phenanthrene and pyrene in soil. However, the presence of Lolium perenne L. significantly enhanced the removal of phenanthrene and pyrene in spiked soil. At the end of 60 d experiment, the extractable concentrations of phenanthrene and pyrene were lower in planted soil than in non-planted soil, about 83.24%-91.98% of phenanthrene and 68.53%-84.10% of pyrene were removed from soils, respectively. The results indicated that the removal of PAHs in contaminated soils was a feasible approach by using Lolium perenne L.     

有机粘土矿物对水中低浓度菲的吸附性能和机理

分别选用十六烷三甲基溴化铵(HDTMA-Br)、四甲基溴化铵(TMA-Br)、聚乙二醇(PEG)表面活性剂改性天然粘土矿物,研究其对水中低浓度多环芳烃类难降解有机物菲的吸附性能和机理,并讨论了有机粘土的用量对吸附菲的性能的影响,验证了有机粘土矿物吸附菲后的稳定性.3种有机粘土矿物对菲的吸附等温线均呈中凹型,表现为分配系数(Kp)逐渐增大,表明吸附是分配作用和溶剂化效应共同作用的结果.根据Kp及土样有机碳含量(foc)所得的经有机碳归一化的分配系数(Koc)基本为常数,远远高于天然土壤/沉积物的Koc.在相同实验条件下,3种有机粘土矿物中HDTMA改性粘土矿物对菲的吸附性能最强,PEG改性粘土矿物次之,TMA改性粘土矿物最差.     

垃圾防渗粘性土对多环芳烃菲(PHEs)的吸附作用研究

研究了持久性有机污染物多环芳烃菲(PHEs)在垃圾防渗粘性土中的吸附机理规律及其吸附模型,探讨了pH值及土样颗粒等影响因素对吸附效果的作用机制,提出了垃圾填埋场防渗粘性土的优化设计。结果表明:菲在粘性土中的吸附过程包括4个阶段,达到吸附平衡的时间为9h;吸附等温线符合Freundlich模型,相关系数为0.98,属于非线性等温吸附;菲的水-土分配系数Kd为0.01,有机碳和水之间的分配系数为14.29;当pH值7.42时,土样对菲的吸附量随pH值的增大而迅速增大;pH值7.42的酸性环境中,对菲的吸附量也变大,但是随着酸性的加强,当pH值6.74之后,吸附能力不再有明显变化;菲的最大吸附量与土体的粘粒含量、比表面积呈正比,由大到小顺序为粘性土粉质粘土细砂。     

玉米幼苗对镉、菲单一与复合污染的生理生化响应

通过室内盆栽实验研究了玉米幼苗在镉、菲污染胁迫14 d后的生理生化响应,并探讨了镉、菲单一与复合污染对玉米幼苗的毒性效应及其致毒机制.结果表明,单一镉(0～50 mg/kg)污染时,镉处理对玉米幼苗地上部分和根系生物量以及可溶性蛋白都无显著影响;随镉处理浓度的增加,玉米幼苗叶片SOD酶活性表现为先增加后降低的趋势,而P...     

Kinetics study of aqueous sorption of phenanthrene to humic acids and sediments

IntroductionThesorptionofhydrophobicorganiccontaminants(HOCs)onnaturalgeosorbentsplaysasignificantroleintheirtransport,degradationandultimatefateintheaquaticenvironment (Alexander,1995 ;Luthy ,1997;Weber,2 0 0 1) .Sincethelate 1970s,theorganicmatter(OM)ha…