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731.
732.
湿式消解法对冷原子吸收测定生物样品中汞产生的干扰 总被引:3,自引:0,他引:3
用不同的湿式消解法对多种生物样品的进行消解测定,分析了实验的干扰因素,并推荐了比较适宜的消解方法。 相似文献
733.
734.
Qiu Shen Liang Liang Xiang Luo Yanjun Li Lianpeng Zhang 《Environmental monitoring and assessment》2017,189(9):471
Drought is a complex natural phenomenon that can cause reduced water supplies and can consequently have substantial effects on agriculture and socioeconomic activities. The objective of this study was to gain a better understanding of the spatial-temporal variation characteristics of vegetative drought and its relationship with meteorological factors in China. The Vegetation Condition Index (VCI) dataset calculated from NOAA/AVHRR images from 1982 to 2010 was used to analyse the spatial-temporal variation characteristics of vegetative drought in China. This study also examined the trends in meteorological factors and their influences on drought using monitoring data collected from 686 national ground meteorological stations. The results showed that the VCI appeared to slowly rise in China from 1982 to 2010. From 1982 to 1999, the VCI rose slowly. Then, around 2000, the VCI exhibited a severe fluctuation before it entered into a relatively stable stage. Drought frequencies in China were higher, showing a spatial distribution feature of “higher in the north and lower in the south”. Based on the different levels of drought, the frequencies of mild and moderate drought in four geographical areas were higher, and the frequency of severe drought was higher only in ecologically vulnerable areas, such as the Tarim Basin and the Qaidam Basin. Drought was mainly influenced by meteorological factors, which differed regionally. In the northern region, the main influential factor was sunshine duration, while the other factors showed minimal effects. In the southern region and Tibetan Plateau, the main influential factors were sunshine duration and temperature. In the northwestern region, the main influential factors were wind velocity and station atmospheric pressure. 相似文献
735.
Nianliang Cheng Yunting Li Bingfen Cheng Xin Wang Fan Meng Qin Wang Qihong Qiu 《环境科学学报(英文版)》2018,30(7):141-154
Characteristics of two serious air pollution episodes(9–15 January, as the winter case; and30 June to 1 July, as the summer case), which occurred in Beijing in 2013 were investigated and compared using multi-method observations and numerical simulations. During these two air pollution episodes, PM_(2.5) concentrations varied significantly within Beijing, with PM_(2.5) concentrations in southern parts of Beijing being significantly higher than in northern areas. Typically, heavy air pollution episodes begin in the southern parts and disperse towards the northern parts of Beijing. Clearly, synoptic patterns and the stability of atmospheric circulation patterns were the main factors controlling air pollution in Beijing.During the winter case, a warm center above 900 h Pa occurred over Beijing. Meanwhile, in the summer case, although there was only a weak inversion, the convective inhibition energy was strong(over 200 J/k G). This clearly influenced the duration of the air pollution event. Except for the local accumulation and secondary atmospheric reactions in both cases, regional straw burnings contributed a lot to the PM_(2.5) concentrations in summer case.Using the CAMxmodel, we established that regional transport contributed almost 59% to the PM_(2.5) averaged concentration in Beijing in the winter case, but only 31% in the summer case. Thus, the winter case was a typical regional air pollution episode, while the summer case resulted from local accumulation straw burnings transportation and strong secondary atmospheric reactions. Given that air pollution is a regional problem in China, consistent and simultaneous implementation of regional prevention and control strategies is necessary to improve regional air quality. 相似文献
736.
巯基葡聚糖凝胶分离富集二溴邻硝基偶氮胂分光光度法测定汞 (Ⅱ) 总被引:2,自引:0,他引:2
研究了溴代十六烷基吡啶、正丁醇、正庚烷和水自制微乳溶液介质中,汞(Ⅱ)与二溴邻硝基偶氮胂的显色反应,采用巯基葡聚糖凝胶分离共存离子并富集汞(Ⅱ),建立了分光光度法测定微量汞(Ⅱ)的新方法。在pH值为6.00的乙酸-乙酸钠缓冲溶液中,汞(Ⅱ)与试剂形成紫红色络合物,其最大吸收峰位于530nm波长处,表观摩尔吸光系数8为3.3×10^5L/(mol·cm)。在显色液中汞(Ⅱ)质量浓度在8.00μg/L~600μg/L范围内符合比尔定律,检出限为0.003mg/L,水、牛奶、化妆品测定的RSD为1.4%~6.1%,加标回收率为96.8%~105%。 相似文献
737.
考察了钙基膨润土钠化过程中改性剂的用量,矿浆浓度,改性时间等对改性效果的影响,并测试了不同超声反应时间、陈化时间等条件下制备的钠化膨润土的性能,如:膨胀容,膨润值和阳离子交换容量CEC,然后分别以Al13-Cl和Al13-SO4方式嵌入矿物层间域中制备柱撑膨润土,考察和比较了不同陈化时间下2种柱撑膨润土煅烧前后的微观结构,及其对污水中锌离子的吸附去除效果,结果表明,Al13-Cl改性方法制备的柱撑膨润土对锌离子的吸附性能明显优于Al13-SO4柱撑效果。 相似文献
738.
Ya-Zhen Zhou Jie Yang Xiao-Li Wang Yue-Qing Pan Hui Li Dong Zhou Yong-Di Liu Ping Wang Ji-Dong Gu Qiang Lu Yue-Feng Qiu Kuang-Fei Lin 《Environmental science and pollution research international》2014,21(19):11500-11509
Chlorinated hydrocarbons are the most common organic pollutants in groundwater systems worldwide. In this study, we developed bio-beads with immobilized anaerobic bacteria, zero-valent iron (ZVI), and activated carbon (AC) powder and evaluated their efficacy in removing 1,1,1-trichloroethane (TCA) from groundwater. Bio-beads were produced by polyvinyl alcohol, alginate, and AC powder. We found that the concentration of AC powder used significantly affected the mechanical properties of immobilized bio-beads and that 1.0 % (w/v) was the optimal concentration. The bio-beads effectively degraded TCA (160 mg L?1) in the anaerobic medium and could be reused up to six times. The TCA degradation rate of bio-beads was 1.5 and 2.3 times greater, respectively, than ZVI + AC treatment or microbes + AC treatment. Measuring FeS produced by microbial reactions indicated that TCA removal occurred via FeS-catalyzed dechlorination. Analysis of clonal libraries derived from bio-beads demonstrated that the dominant species in the community were Betaproteobacteria and Gammaproteobacteria, which may contribute to the long-term stability of ZVI reactivity during TCA dechlorination. This study shows that the combined use of immobilized anaerobic bacteria, ZVI, and AC in bio-beads is effective and practical for TCA dechlorination and suggests they may be applicable towards developing a groundwater treatment system for the removal of TCA. 相似文献
739.
不同碳源条件下聚磷菌代谢特性 总被引:3,自引:0,他引:3
利用2套SBR系统在厌氧好氧交替条件下对聚磷菌(phosphorus accumulating organisms,PAO)进行富集,分别采用乙酸和丙酸作为碳源。通过对典型周期内磷酸盐,聚羟基烷酸(polyhydroxyalkanoates,PHAs),糖原和多聚磷酸盐变化情况的分析,探讨了不同碳源下,聚磷菌胞内碳源物质的代谢机理以及其对于生物除磷的影响。结果表明,以乙酸为碳源时,PHAs的合成量和分解量都要高于丙酸为碳源,且PHAs主要成分以聚-β-羟丁酸(poly-β-hydroxybutyrate,PHB)为主,污泥的比释磷速率和比吸磷速率都要高于丙酸为碳源的情况。 相似文献
740.
Chao Xu Jinghui Ding Jiguo Qiu Yun Ma 《Journal of environmental science and health. Part. B》2013,48(11):960-966
A highly effective acetochlor-degrading bacterial strain (D-12) was isolated from the soil of a pesticide factory. The strain was identified as Achromobacter sp. based on its 16S rRNA gene sequence. The strain D-12 optimally degrades acetochlor at a pH of 7.0 and a temperature of 30°C in a mineral salts medium (MSM). Approximately 95% of acetochlor was degraded by the stain treated at a concentration of 10 mg L?1 after 5 days of incubation. A chiral high performance liquid chromatography (HPLC) system was used to study the enantioselectivity during the process. However, no obvious enantioselective biodegradation was observed. The primary biodegradation acetochlor products were identified by high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS). The results indicated that the strain D-12 could be applied in the bioremediation of an acetochlor-polluted environment. 相似文献