纳米Al_2O_3和Cd联合暴露对铜锈环棱螺体内Cd的生物积累和抗氧化酶活性的影响

金属氧化物纳米颗粒的广泛应用导致它们大量地释放到水环境中,其独特的理化性质有可能改变水环境中其他共存污染物(如重金属)的生态毒性。为评价沉积物中纳米氧化铝(Al2O3-NPs)对重金属Cd生态毒性的影响,采用底栖生物慢性暴露研究了Al2O3-NPs存在条件下Cd在底栖动物铜锈环棱螺体内生物积累的变化和Cd对肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与脂质过氧化指标丙二醛(MDA)以及Ⅱ相反应的关键酶谷胱甘肽-S-转移酶(GST)的影响。结果表明,低Cd浓度(5μg·g-1)时,Al2O3-NPs对Cd生物积累没有影响;中、高Cd浓度(25、100μg·g-1)时,Al2O3-NPs显著促进Cd的生物积累,Al2O3-NPs对Cd的生物转运具有明显的携带效应。低Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的SOD活性与对照组相比均没有显著差异;中Cd浓度时,SOD活性显著升高,而高Cd浓度时,SOD活性显著下降,而且Al2O3-NPs处理组的SOD活性显著低于无Al2O3-NPs处理组,Al2O3-NPs的存在加重了Cd对肝胰脏细胞的氧化胁迫或损伤。高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的MDA水平均显著升高,但Al2O3-NPs处理组的MDA水平显著低于无Al2O3-NPs处理组,进一步证明Al2O3-NPs对Cd氧化损伤的增强作用。中、高Cd浓度时,无Al2O3-NPs处理组和Al2O3-NPs处理组的GST活性均显著下降,但Al2O3-NPs处理组的GST活性均显著低于无Al2O3-NPs处理组,同样说明了Al2O3-NPs对Cd毒性的增强作用。本研究提供了在沉积物-底栖动物体系中Al2O3-NPs促进重金属生物积累的证据,而且Cd毒性的变化与肝胰脏中Cd的生物积累水平的变化基本一致,在中、高Cd浓度下,由于Al2O3-NPs的存在显著促进了Cd的生物积累,因而增强了Cd对铜锈环棱螺的生态毒性。     

全氟辛烷磺酸(PFOS)和多壁碳纳米管(MWCNTs)复合对斑马鱼外周血红细胞DNA的损伤

为了评价全氟辛烷磺酸(PFOS)和多壁碳纳米管(MWCNTs)对水环境及鱼类的影响,以斑马鱼为模式生物,研究了PFOS和MWCNTs复合对斑马鱼外周血红细胞的DNA损伤。将成年斑马鱼暴露于PFOS(0.2、0.4、0.8、1.6 mg·L-1)、MWCNTs(50 mg·L-1)、PFOS+MWCNTs(0.2+50、0.4+50、0.8+50、1.6+50 mg·L-1)和对照溶液中30 d后,断尾取血进行微核试验和彗星试验。结果表明:PFOS和MWCNTs均可造成斑马鱼外周血红细胞的DNA损伤。1.6 mg·L-1PFOS处理组的微核率、Olive尾矩及尾长分别为(36.3±0.25)‰、(87.91±14.90)μm和(250.49±34.71)μm。PFOS与MWCNTs复合后,斑马鱼外周血红细胞的DNA损伤效应明显降低。复合处理组斑马鱼外周血红细胞的微核率、Olive尾矩及尾长均低于PFOS单独处理相。1.6 mg·L-1复合处理组的微核率、Olive尾矩及尾长比PFOS单独处理组分别降低了24.7%、68.9%、52.4%。因此,在实验浓度范围内,MWCNTs可以降低PFOS对斑马鱼外周血红细胞的DNA损伤。     

磺化石墨烯对小麦幼苗生长及生理生化指标的影响

随着石墨烯生产量和使用量的不断增大,其对生态环境的风险逐渐引起了环境学家的关注。采用水培试验,探究了磺化石墨烯(SGO)对小麦幼苗的生长、抗氧化酶活性及脂质过氧化的影响。结果表明:在培养10 d后,低浓度磺化石墨烯对小麦根系的生长有显著促进作用(P0.05),200 mg·L-1浓度处理与对照处理相比提高了84.3%,随着浓度增加促进作用逐渐减弱,1 000 mg·L-1时与对照相比提高了19.9%。但对小麦地上部的生长没有影响。磺化石墨烯处理的小麦幼苗根系和叶片组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)及丙二醛(MDA)都呈现先下降后上升的趋势。当磺化石墨烯浓度低于200 mg·L-1时,处理组小麦抗氧化酶的活性及MDA含量相对于对照处理大都有所降低,说明低浓度时磺化石墨烯没有对小麦的生长产生氧化胁迫,这与磺化石墨烯可能具有一定的抗氧化能力有关,而高浓度时由于产生氧化胁迫使各项生理生化指标逐渐上升。本实验结果为石墨烯材料对植物的毒理学研究提供了基础数据。     

Mass concentrations and temporal profiles of PM10, PM2.5 and PM1 near major urban roads in Beijing

Mass concentrations of PM₁₀, PM_2.5 and PM₁ were measured near major roads in Beijing during six periods: summer and winter of 2001, winter of 2007, and periods before, during and after the 2008 Beijing Olympic Games. Since the control efforts for motor vehicles helped offset the increase of emissions from the rapid growth of vehicles, the averaged PM_2.5 concentrations at roadsides during the sampling period between 2001 and 2008 fluctuated over a relatively small range. With the implementation of temporary traffic control measures during the Olympics, a clear “V” shaped curve showing the concentrations of particulate matter and other gaseous air pollutants at roadsides over time was identified. The average concentrations of PM₁₀, PM_2.5, CO and NO decreased by 31.2%, 46.3%, 32.3% and 35.4%, respectively, from June to August; this was followed by a rebound of all air pollutants in December 2008. Daily PM₁₀ concentrations near major roads exceeded the National Ambient Air Quality Standard (Grade II) for 61.2% of the days in the non-Olympic periods, while only for 12.5% during the Olympics. The mean ratio of PM_2.5/PM₁₀ near major roads remained relatively stable at 0.55 (±0.108) on non-Olympic days. The ratio decreased to 0.48 (±0.099) during the Olympics due to a greater decline in fine particles than in coarse-mode PM. The ratios PM₁/PM_2.5 fluctuated over a wide range and were statistically different from each other during the sampling periods. The average ratios of PM₁/PM_2.5 on non-Olympic days were 0.71.     

Development of pretreatment protocol for DNA extraction from biofilm attached to biologic activated carbon (BAC) granules

The biologic activated carbon (BAC) process is widely used in drinking water treatments. A comprehensive molecular analysis of the microbial community structure provides very helpful data to improve the reactor performance. However, the bottleneck of deoxyribonucleic acid (DNA) extraction from BAC attached biofilm has to be solved since the conventional procedure was unsuccessful due to firm biomass attachment and adsorption capacity of the BAC granules. In this study, five pretreatments were compared, and adding skim milk followed by ultrasonic vibration was proven to be the optimal choice. This protocol was further tested using the vertical BAC samples from the full-scale biofilter of Pinghu Water Plant. The results showed the DNA yielded a range of 40 μg·g^-1 BAC (dry weight) to over 100 μg·g^-1 BAC (dry weight), which were consistent with the biomass distribution. All results suggested that the final protocol could produce qualified genomic DNA as a template from the BAC filter for downstream molecular biology researches.     

Sorption of tetracycline to sediments and soils: assessing the roles of pH,the presence of cadmium and properties of sediments and soils

Batch sorption experiments were conducted to evaluate the sorption behavior of tetracycline (TC, H₃L) on sediments and soils in the presence and absence of cadmium (Cd), as affected by pH and properties of sediments and soils. The results indicated stronger nonlinearity and higher capacity of TC sorption on sediments than on soils. Sorption of TC also strongly depended on environmental factors and sediment/soil properties. Lower pH facilitated TC sorption through a cation exchange mechanism, which also took place at pH values above 5.5, where TC existed as a zwitterion (H₂L⁰) or anions (HL^- and L^2-). When pH was above 7, however, ligand-promoted dissolution of TC might occur due to TC weakening the Al-O bond of aluminum oxide and the Fe-O bond of iron oxide. Natural organic matter (NOM) plays a more important role in TC sorption than cation exchange capacity (CEC) and clay contents. The presence of Cd (II) increased TC sorption on both sediments and soils, which resulted from the decrease of equilibrium solution pH caused by Cd²⁺ exchange with H⁺ ions of sediment/soil surfaces. The increase of TC sorption was also related to the formation of TC-Cd complexes, where Cd²⁺ acted as a bridge between the sediment/soil and TC.     

Three-dimensional hydrodynamic modeling of the Chicago River, Illinois

We present and describe results from a three-dimensional model applied to the Chicago River under a wet weather condition. Chicago River is an integral part of Chicago, the third largest city in United States, for recreational, commercial and industrial purposes. Although the flow in the Chicago River is supposed to be from north to south, the flow acquires a three-dimensional nature at various points in the river. The reasons for the three dimensionality of the flow can be attributed to the dynamic boundary conditions generated by combined sewer overflow (CSO) events during wet weather conditions, as well as the presence of confluences of various branches of the river with creeks and slips. This work presents the hydrodynamic application and validation of a three dimensional numerical model, which was used to simulate the flow in the Chicago River for a period of 8?days in September of 2008, during which the torrential rains in the city of Chicago led to intense CSO events. The numerical model used for the aforementioned exercise is the Environmental Fluid Dynamics Code (EFDC) which solves the three dimensional vertically hydrostatic, free surface, turbulence averaged equations of motions for a variable density fluid. The results obtained by the numerical model were validated with the help of stage values obtained from the USGS gauging station [Station No. 05536123] present inside the domain of interest. It was estimated that during the storm September 2008, several billion gallons of water were discharged into Lake Michigan from the Chicago River Controlling Works to prevent city flooding. The 3D model also provides a tool for the management of the waterways, in particular for future analysis of different alternatives being considered to reverse the Chicago River once again with the goal of preventing the passage of invasive species (e.g. Asian carp) towards the Great Lakes.     

Magnetic semiconductor nano-photocatalysts for the degradation of organic pollutants

Photocatalytic degradation of organic pollutants using suspended and dispersed semiconductor nano-photocatalysts in wastewater holds unique advantages, including high activity, low cost, solar utilization, and complete mineralization. But the recovery and reuse of photocatalysts are difficult because the fine particles are easily discharged in waters. Immobilization of photocatalysts on supports such as glass and zeolite results in decreased activities due to the low specific area and slow mass transfer. Furthermore, a large amount of the photocatalysts will result in colored contamination. Therefore, it is necessary to develop photocatalysts with a separation function for the reusable and cyclic application. In order to take advantage of the high activity and enable the semiconductor nano-photocatalysts to be reused, the concept of magnetic photocatalysts with separation function was raised. We review the photocatalytic principle, structure, and application of the magnetic semiconductor catalysts.     

灰色聚类法综合评价滴水湖水系环境质量

将滴水湖水系看作一个灰色系统进行研究,利用灰色聚类理论,以地表水环境标准和富营养化分级标准为基础建立灰类评价体系,确定聚类指标的隶属度和标准灰类的权重,得到各聚类指标对标准灰类的聚类系数,最大聚类系数关联的等级即水体质量等级。2010年,每2周1次对滴水湖水系11个监测点的溶解氧（DO）、化学需氧量（CODMn）、五日生化需氧量（BOD5）、总磷（TP）、总氮（TN）、氨氮（NH3-N）、透明度（SD）及叶绿素a（Chl.a）进行监测,取各指标的年均值,建立灰类评价系统。结果表明：滴水湖水源大治河及引水干道随塘河处水质属于Ⅳ类～Ⅴ类,呈富营养化和极度富营养化状态;闸外引水河芦潮引河段水质类型为Ⅲ类,为富营养化水平;闸内引水河道水质总体呈现富营养化状态,水质类型为Ⅲ类;滴水湖湖区水体质量良好,水质类型为Ⅲ类,呈中营养水平。     

冷藏技术对发光细菌活性及毒性测试性能的影响

由于发光细菌的在线毒性监测技术受到了细菌生物活性稳定性保持问题的制约,探索一种脱脂牛奶菌悬液冷藏复苏方法,以提高发光细菌活性的保持时间。比较了明亮发光杆菌新鲜菌液冷藏、冻干粉菌悬液冷藏和脱脂牛奶菌悬液冷藏对发光细菌生物活性的影响,同时,比较了不同渗透压调节液对菌悬液急性毒性测试的灵敏度和稳定性的影响。结果表明,质量分数为25%的脱脂牛奶可提高发光细菌生物活性的稳定性,菌悬液冷藏7d后复苏,相对发光率仍可达92%。2%NaCl和10%蔗糖为渗透压调节液时,冷藏至第7天的发光细菌脱脂牛奶菌悬液对重金属毒性测试的灵敏度,与新鲜菌液基本相同,但添加蔗糖降低了其对有机物的测试灵敏度。利用发光细菌脱脂牛奶冷藏菌悬液对Zn~(2+)进行连续7d的毒性测试,EC_(50)的变异系数小于15%,结果稳定性良好。