SD-3A型自动测氡仪检查标定中应注意的问题

本文以安徽省庐江台在日常的维护和标定工作中所取得的数据为依据,结合多次检查标定的经验,简述了SD-3A型自动测氡仪在日常观测和检查标定过程中应特别注意的几个问题,如仪器工作方式的选择、及时调整仪器工作高压、仪器避光问题、标定气路选择等,文章分析了导致这些问题出现的原因及对观测结果的影响,并给出了正确的操作方法,确保仪器产出的数据真实、连续、可靠.     

一种气溶胶测量仪器标定系统的设计及性能评估

对气溶胶测量仪器进行准确标定是保证大气环境及污染源颗粒物测量数据质量的重要前提.本研究搭建了一套多分散在线标定气溶胶测量仪器的系统,该系统采用超声气溶胶发生装置产生多分散颗粒物,并用空气动力学粒径谱仪对颗粒物粒径分布进行测量.评测结果表明该系统干燥腔室内气溶胶稳定、均匀,且符合对数正态分布.以采样器为例,已有研究多使用单分散离线标定方法对采样器切割性能进行标定,该方法操作繁琐、实验周期长.利用多分散在线标定系统对PM_(2.5)和PM_(10)双级虚拟撞击采样器进行标定,并与单分散离线标定方法进行了对比,两套系统的标定结果呈现较好的一致性,但多分散在线方法大大缩短了标定实验周期.     

基于单片机原理的土壤盐分实时观测系统

土壤中盐分浓度的观测是研究土壤盐分运移问题的前提与基础,目前所用的土壤盐分浓度观测仪器在完成多点长时间实时观测任务时存在较大的困难,迫切需要研发多点长时间连续观测的土壤盐分实时观测系统。基于单片机原理开发了土壤盐分实时观测系统,新研发的土壤盐分实时观测系统主要包括信号采集单元、数据处理单元和上位机控制单元3个功能模块,可同时对多个土壤盐分传感器所采集的土壤盐分浓度数据进行实时显示、传输、储存,具有反应灵敏、精度高、仪器轻便等特点。通过将该系统应用于一维土柱盐分运移试验中的土壤盐分浓度观测,结果表明该系统可持续稳定运行500 h以上,且工作性能稳定、数据观测准确,证明其在土壤盐分浓度观测中具有可靠性。基于单片机原理的土壤盐分实时观测系统在室内与野外土壤盐分运移试验中具有良好的应用前景。     

北京地区大气气溶胶光学厚度的观测和分析

利用中国科学院大气物理研究所研制的中分辨率太阳-天光光谱自动观测系统(MORSAS)于北京对太阳直射光谱和天空散射光谱进行准连续观测,其中无云情况(包括晴天和浑浊天气)下的观测资料用于获取大气气溶胶光学厚度.该仪器与一台美国NASA主持的国际气溶胶观测网仪器CIMEL CE-318太阳光度计进行对比观测,二者所得结果一致性较好.作者给出了近3年北京地区大气气溶胶光学厚度和表征粒子谱宽度的Angstrom指数(a)的变化情况.与20世纪90年代中期相比,近3年北京秋冬季气溶胶光学厚度有所减小,表明北京的环境治理有一定成效;而春季气溶胶光学厚度则在近2年有明显增加,源自沙尘天气,且Angstrom指数亦变小,表明大粒子比例增加,因此需要加强对沙尘源的治理.     

GD—L2型流气式固体氡源标定测氡仪的方法及影响因素浅析

GD—L2型流气式固体氡源具有操作简便、体积小、易携带、氡产生率较稳定的性能,与RN—150型负压氡源相比较,它最大的特点就是常压下开放式采样,标定K值的准确度往往受操作熟练程度和气压等气候条件的影响。为减小误差提高K值准确度,标定时采用"双连法"对被标仪器和闪烁室进行采样,根据标定时当地的气压和温度对恒流采样泵流速进行改正,实地验证气压等因素对标定结果的影响,本文还对标定方法和技巧进行定性分析和阐述。     

夏秋季北京及河北三城市的大气污染联合观测研究

为评估北京西南方向城市群对北京大气污染的影响,于2009年夏秋季节（2009年7月16日～10月15日）,利用自动在线大气环境观测仪器,对北京及太行山东侧河北省的3个城市涿州、保定和石家庄进行了大气污染物PM10、NOx和O3的联合观测研究.结果表明,夏秋季节4个城市的首要污染物均为可吸入颗粒物（PM10）,平均质量浓...     

北京2011年10月连续重污染过程气团光化学性质研究

于2011年10月份对北京市大气痕量气体、颗粒物及单颗粒组成进行了观测,分析了观测期间各项污染物的关系、单颗粒物物理化学特征及气团光学性质,并结合后向气流轨迹分析了污染物来源.结果显示,2011年10月份存在3次明显的重污染过程:第1次过程区域性特征明显,气团光化学年龄较长,主要来源于河北省和山西省交界处;第2次过程呈区域与局地性叠加特征,气团光化学年龄开始呈现缩短趋势,气团主要来源于河北省;第3次过程中局地特征较明显,气团光化学年龄较短,主要来源于京津及河北省中北部.     

APS-SMPS-WPS对南京夏季气溶胶数浓度的对比观测

为了对比3321型空气动力学粒径谱仪(APS)、3081/3085型气溶胶粒径谱仪(SMPS)和宽范围粒径谱仪(WPS)对气溶胶数浓度的观测性能,于2010年夏季在南京信息工程大学校内使用上述三台仪器进行了同步观测.将得到的数据进行对比,并结合校内自动气象站的气象资料对0.01~10μm气溶胶粒子的数浓度、日变化规律及谱分布特征进行分析.结果表明,3台仪器在总体数浓度变化趋势上表现出较好的一致性,但相同粒径段的粒子浓度NSMPS>NWPS>NAPS.SMPS比WPS尺度分辨率高,粒径范围在0.02~0.2μm时,SMPS与WPS相关性较好;APS测量气溶胶数浓度谱的连续性较WPS好.3种仪器在观测日变化趋势上都表现出双峰型,但SMPS的峰值浓度和出现峰值的粒径范围均高于或大于WPS.各类气象条件及降水对仪器间的测量误差影响不大.     

基于腔衰减相移光谱法的二氧化氮分析仪的设计与应用

基于腔衰减相移光谱法设计了一套二氧化氮在线分析仪,通过优化测量参数,该仪器可长期稳定运行,其时间分辨率为60 s,检出限为0.191 ppb,在0~300 ppb范围内,NO₂气体浓度与相位正切信号值具有较好的二次拟合关系,R²为0.9995.另外,该仪器在泰安站进行了长期外场观测,并与改装后的进口商品化仪器PKU-Thermo 42i-TL进行比对实验,结果表明,两者的测量结果一致性较好,R²=0.9811,表明其具有良好的运行稳定性和测定结果准确性,适用于环境大气二氧化氮浓度的在线监测.外场观测结果表明,春季泰安站二氧化氮浓度均值为12.39 ppb,有明显日变化规律.     

银川台小口子泉水氡对比观测实验研究

本文以小口子泉模拟水氡观测为基础进行日常观测实验.通过加密观测、升高鼓泡水温和降低鼓泡水温实验,认为小口子泉水氡与泉点气温、鼓泡水温变化有关;不同的鼓泡水温对观测氡值有一定影响,但是影响幅度不大.通过不同的观测仪器对比实验,发现不同的观测仪器之间存在系统误差,但不影响观测资料的正常变化形态和幅度.两次实验可以为台站观测人员和分析预报人员掌握观测资料动态变化的影响因素、剔除非地震异常干扰提供帮助.     

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.