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火焰原子吸收法测定水中锰的不确定度分析 总被引:1,自引:0,他引:1
测量不确定度是表征合理地赋予被测量值的分散性,与测量结果相联系的参数.通过火焰原子吸收法对水中锰测定不确定度进行分析,确定锰测量不确定度最主要来源是工作曲线.通过合理选择不确定度分量,建立有效的质量控制程序,优化评定过程,达到时不确定度合理分析的目的. 相似文献
223.
Jian Zhou Zegang Wang Zhiwei Huang Chao Lu Zhuo Han Jianfeng Zhang Huimin Jiang Cailin Ge Juncheng Yang 《环境科学学报(英文版)》2014,26(3):650-661
The responses of sulfur (S) uptake assimilation-related genes' expression in roots of two rice cultivars to cadmium (Cd), bensulfuron-methyl (BSM) and their co-contamination (Cd+BSM) were investigated by gene-chip microarray analysis and quantitative real-time PCR (QRT-PCR) technology. Treatments of Cd and Cd+BSM induced expression of sulfate transporter and permease genes, and promoted sulfate uptake in rice roots. Cd+BSM could alleviate Cd toxicity to cv. Fengmeizhan seedlings, probably due to Cd+BSM promoting greater S absorption by seedlings. Cd and Cd+BSM induced expression of sulfate assimilation-related genes, and thus activated the sulfur assimilation pathway. Cd and Cd+BSM induced expression of phytochelatin synthase and metallothionein genes, and induced expression of glutathione S-transferases (GSTs), glutathione synthase (GS) and S- containing antioxidation enzyme genes, which detoxified Cd2+. It is suggested that (to cope with the toxicity of Cd, BSM and their co-contamination) the S uptake and assimilation pathway was activated in rice roots by increased expression of related genes, thus enhancing the supply of organic S for synthesis of Cd or BSM resistance-related substances. 相似文献
224.
根据样品中被测元素的特点,采用硝酸-氢氟酸-高氯酸-硼酸-硝酸和硝酸体系,对电路板中金属元素进行消解,用电感耦合等离子体原子发射光谱法对电路板中的金属元素含量进行定量分析。该方法具有简单、准确的特点,可以快速分析电路板中的金属元素含量。 相似文献
225.
The nitrogen changes and the nitrogen mass balance in a free water surface flow constructed wetland (CW) using the four-year monitoring data from 2008 to 2012 were estimated. The CW was composed of six cells in series that include the first settling basin (Cell 1), aeration pond (Cell 2), deep marsh (Cell 3), shallow marsh (Cell 4), deep marsh (Cell 5) and final settling basin (Cell 6). Analysis revealed that the NH4+-N concentration decreased because of ammonification which was then followed by nitrification. The NO4+-N and NO4+-N were also further reduced by means of microbial activities and plant uptake during photosynthesis. The average nitrogen concentration at the influent was 37,819 kg/year and approximately 45% of that amount exited the CW in the effluent. The denitrification amounted to 34% of the net nitrogen input, whereas the accretion of sediment was only 7%. The biomass uptake of plants was able to retain only 1% of total nitrogen load. In order to improve the nutrient removal by plant uptake, plant coverage in four cells (i.e., Cells 1, 3, 4 and 5) could be increased. 相似文献
226.
Huirong Lin Chengsong Ye Lu Lv Clark Renjun Zheng Shenghua Zhang Lei Zheng Yidong Zhao Xin Yu 《环境科学学报(英文版)》2014,26(8):1763-1768
A combined approach of physicochemical extraction and sulfur K-edge X-ray absorption near-edge structure(XANES) spectroscopy was applied to characterize the extracellular polymeric substances(EPS) of typical bacterial biofilms in this study. Physicochemical analysis showed variation of the contents of DNA,polysaccharide and protein in different fractions of EPS in different mediums. The sulfur K-edge XANES analysis yielded a variety of spectra.Spectral fitting of the XANES spectra utilizing a large set of model compounds showed that there was more reduced sulfur in both LB-EPS(loosely bound EPS) and TB-EPS(tightly bound EPS) of all the biofilms in LB medium than in R2 A medium. More oxidized sulfur was identified in LB-EPS than that in TB-EPS,suggesting different niches and physiological heterogeneity in the biofilms. Our results suggested that the sulfur K-edge XANES can be a useful tool to analyze the sulfur speciation in EPS of biofilms. 相似文献
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制备了3种乙酰胺-无机盐类低共熔离子液体,测定了其物理性质并将其应用于SO2气体的吸收。结果表明,这些低共熔离子液体具有和传统离子液体相似的性质,例如熔点低、粘度低、密度高、电导率高以及较宽的液态范围。此类离子液体对SO2气体有较好的吸收能力,而且吸收量和温度的关系满足二次多项式方程。红外光谱结果表明吸收是可逆的,回收的离子液体可高效重复使用至少5次。乙酰胺-硫氰酸钠(3∶1)对SO2的质量分数吸收量为0.554 g/g(20℃,1 atm),具有吸收量高、成本低和易回收的优势,是一个很有前景的SO2吸收剂。 相似文献
229.
对桂林市3个城区交警按年龄、工龄、工种和性别比例采集尿样44件,测定和研究尿样汞浓度分布状况,并采集普通人群发样128件加以对照。结果表明,车流量越大,从事交警的工龄越长,交警尿样中汞浓度越高。从事外勤工作交警尿样汞平均浓度高于内勤工作交警。桂林市交警尿样汞平均浓度为(2.372±0.657)μg/L,是普通人群(0.348±0.193)μg/L的6.82倍。对交警与普通人群以及外勤交警与内勤交警尿样的汞浓度分别进行独立样本t检验,差异性均显著。男性交警尿样汞平均浓度为(2.429±0.628)μg/L,略高于女交警(2.114±0.722)μg/L。对不同性别交警尿汞浓度进行独立样本t检验,差异性不显著。无铅汽油的使用降低了大气中铅的污染,但汞的污染依然存在,应当引起高度重视。 相似文献
230.