低浓度苯系物在新疆干旱区土壤中的吸附行为研究

采集新疆干旱区石化废水库附近区域土壤,以苯、甲苯、乙苯、二甲苯(间、对二甲苯)等典型苯系物为研究对象,系统研究低浓度苯系物在干旱区土壤上的吸附行为,分析土壤有机质含量,溶液p H、溶液含盐量、温度对苯系物吸附的影响。结果显示土壤对低浓度苯系物的吸附16 h达到平衡;吸附等温线经拟合后符合Henry直线型吸附模型;土壤对苯系物的吸附量随着土壤有机质含量的增加而增加,土壤有机质含量与吸附量呈显著正相关(P0.01,R2≥0.919);溶液p H值对吸附过程无明显作用;随着溶液含盐量增大,土壤对苯系物的吸附量表现为先减小,再稳定;温度升高会抑制土壤对苯系物的吸附作用。     

佳木斯市新装修居室室内空气污染现状与防治对策

介绍了室内空气中主要污染物甲醛和苯系物的采样方法,并应用酚试剂分光光度法测定室内空气中甲醛的含量、气相色谱-质谱法测定室内空气中苯系物的含量,对所测定的数据进行分析讨论,进而提出防治对策。     

北京市道路空气中挥发性有机物时空分布规律

为研究城市交通道路空气中挥发性有机化合物(VOCs)的污染状况、变化规律和不同道路类型的浓度特点,于2008年5月—2009年7月对北京市3种典型道路(街道峡谷、交叉道路和开阔道路)进行空气质量监测. 采用气相色谱法测定道路空气中非甲烷烃(NMHCs)、苯系物(苯、甲苯和二甲苯)的质量浓度. 结果表明:北京市道路空气中挥发性有机化合物污染比较严重,其中ρ(NMHCs)日均值为1.0～3.3 mg/m3,ρ(苯系物)日均值为8.8～80.0 μg/m3. 污染物浓度日变化多呈现双峰型. 选取1,4,7和10月为不同季节的代表月份,7月的ρ(NMHCs)和ρ(苯系物)均最高,10月最低. 3种典型道路中,街道峡谷的污染物质量浓度高于另外2种道路. 道路附近的挥发性有机物质量浓度主要受到机动车排放、气象条件和地形条件等的影响.      

大学校园室内BTEX浓度水平变化规律及健康风险

采用Tenax-TA吸附/热脱附-气相色谱法(TD-GC)对大学校园室内外空气中5种苯系物(BTEX,苯、甲苯、乙苯、间/对-二甲苯和邻二甲苯)的平均浓度进行了检测。检测结果显示,5种苯系物的平均浓度均低于国家标准值。被测空气的苯系物中甲苯所占比例最大,为27.9%～32.0%。室内BTEX浓度稍高于室外,多数采样点的室内浓度与室外浓度比值(CI/CO)大于1.0。通风可有效降低空气中苯系物浓度。大学校园室内空气中的苯对学生的致癌风险为3.67×10-7～1.09×10-6。     

活性炭纤维吸附苯系物影响因素的研究

研究了吸附法去除室内苯系物。实验用活性炭纤维(ACF)作为苯系物的吸附剂,苯、甲苯作为苯系物的代表物。研究苯系物的浓度、气流量及填充密度等条件对活性炭纤维吸附性能的影响。实验结果表明:初始浓度大的苯系物穿透时间短;当两组分气体(苯、甲苯)混合吸附时,吸附能力强的甲苯有置换吸附能力弱的苯的现象发生;气流量加大会较快到达穿透点和吸附饱和点,使穿透曲线发生左移,曲线斜率不变;填充密度对穿透时间与饱和时间都有影响,密度大有利于吸附。     

试析气相色谱法测定环境空气中苯系物的要点

随着我国城市化进程的不断加快,我国的环境污染问题越来越严峻。苯系物作为空气污染物中的重要一种,其对人体的健康有着非常大的危害。本文从气相色谱法测定环境空气中苯系物浓度的原理及方法出发,对影响测定结果的因素进行了分析。     

关于固相萃取技术富集水中苯系物的探讨

苯系物尤其是苯、甲苯和二甲苯作为重要溶剂和基本化工原料,被广泛应用于油漆、农药、医药、有机化工等行业,由此而产生的废水、废气便成为河流、空气和地下饮用水等有机污染物的重要来源。除苯是已知的致癌物以外,其它几种化合物对人体和水生生物均有不同程度的毒性。在我国水环境中优先控制污染物黑名单中,苯、甲苯、乙苯及二甲苯的三种异构体均榜上有名。因此,测定水中苯系物含量对环境保护具有重要的意义。本文基于固相萃取（SPE）技术富集水样中苯系物的思路,选择苯、甲苯、乙苯、对二甲苯、邻二甲苯、苯乙烯和异丙苯作为目标化合物,对C18键合相吸附剂富集水中苯系物的吸附和脱附过程的参数优化进行了研究,为建立一种简便、高效的水中苯系物的检测方法提供了依据。     

土壤中苯系物的吹扫捕集-气相色谱-质谱测定方法

采用吹扫捕集-气相色谱-质谱联用(PT-GC-MS)法,研究了污染土壤中苯系物(包括苯、甲苯、乙苯、对间二甲苯、邻二甲苯和异丙苯)的测定方法,优化了吹扫捕集作为北京潮土中苯系物预处理方法的参数. 结果表明,吹扫时间11 min,解吸温度190 ℃和解吸时间0.5 min为最佳的吹扫捕集方法参数. 采用PT-GC-MS法测定土壤中的苯系物的平均加标回收率为99.0%～103.9%,相对标准偏差为10.3%～17.5%(n=7);苯系物的检出限为1.6～2.8 μg/kg,定量限为5.4～9.6 μg/kg. 将研究结果与文献中的苯系物监测质量控制参数进行比较发现,由于采用有机质含量低、砂质壤土质地的北京潮土为研究对象,使该试验的回收率均高于文献中的结果;同时,相对标准偏差和检出限与文献中的结果也存在差异,主要是由于挥发性污染物所赋存的介质及实验仪器操作条件不同所致.      

气相色谱法分析废气中的挥发性苯系物

建立活性炭吸附二硫化碳解析,气相色谱法分析废气中的苯系物方法.以8种苯系物为研究对象,从基本参数着手,探求分析的最佳条件.该方法操作简便,灵敏度高,能够符合日常工作的要求.     

工业污染场地土壤苯系物的检测方法比较研究

以工业污染场地为研究对象,比较和分析了静态顶空、吹扫捕集和固相微萃取等3种前处理方法对土壤中苯系物的气相色谱检测结果差异.结果表明,静态顶空和吹扫捕集两种方法均可对土壤苯系物进行定性定量分析,固相微萃取因土壤有机污染物对萃取探头造成溶解损害而不能检测.静态顶空法检测苯系物各组分的回收率为95.2%～98.2%,吹扫捕集...     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.