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301.
302.
介绍了用GC/MS法分析大气中挥发性有机污染物。以8种苯系物为试剂进行试验,结果表明:相对标准偏差小于9%,回收率大于95%;当采样量为10L时,8种苯系物的最低检出质量浓度均低于2μg/m^3。 相似文献
303.
Anirban Dutta Venugopal Vasudevan Lata Nain 《Journal of environmental science and health. Part. B》2016,51(1):24-34
An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL?1, 265.6 and 1805.2 µg mL?1 and 1.85 and 16.12 µg mL?1, respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples, however, was degraded up to T4 treatments and was persistent in the T5 treatment. Probably, accumulation of this metabolite inhibited atrazine/cyanuric acid degradation by the enrichment culture in undiluted wastewater. 相似文献
304.
利用高炉瓦斯泥中的锌制备活性氧化锌的研究 总被引:1,自引:0,他引:1
利用高炉炼铁瓦斯泥中的锌,采用火法富集和湿法浸取制取活性氧化锌。考察了温度、时间对火法富集产品中氧化锌含量和原料瓦斯泥中锌挥发率的影响,确定了富集工艺的最佳条件为:在氮气氛围下,温度从常温以10℃/min升温至1 000℃并且在1 000℃下保持1 h,得到的富集产品中氧化锌含量82.24%;瓦斯泥中锌挥发率97%。同时考察了温度、氨水用量、碳酸氢铵用量和液固比等因素对氧化锌浸取率的影响。确定的最佳工艺条件为:浸取温度40℃,氨水用量为理论量的2倍,碳酸氢铵用量为理论量的2倍,液固比4∶1,浸取时间2 h,氧化锌浸取率达99.9%。湿法制得的活性前驱体碱式碳酸锌,经煅烧得到纯度为98.4%的活性氧化锌产品,氧化锌的总回收率达95.3%。 相似文献
305.
Atrazine degrading enrichment culture was prepared by its repeated addition to an alluvial soil and its ability to degrade atrazine in mineral salts medium and soil was studied. Enrichment culture utilized atrazine as a sole source of carbon and nitrogen in mineral salts medium and degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as additional source of carbon and nitrogen, respectively. Biuret was detected as the only metabolite of atrazine while deethylatrazine, deisopropyatrazine, hydroxyatrazine and cyanuric acid were never detected at any stage of degradation. Enrichment culture degraded atrazine in an alkaline alluvial soil while no degradation was observed in the acidic laterite soil. Enrichment culture was able to withstand high concentrations of atrazine (110 μg/g) in the alluvial soil as atrazine was completely degraded. Developed mixed culture has the ability to degrade atrazine and has potential application in decontamination of contaminated water and soil. 相似文献
306.
Heavy metals in respirable suspended particulate matter (RSPM) were analyzed for different seasons, from July 2002 to December
2002, at different locations in Hisar (Haryana, India). The samples were analyzed for Pb, As, Ni, Cu, Mn, Fe and Mg on atomic
absorption spectrophotometer (AAS) in air-acetylene flame. The concentration of heavy metals was more in the studied residential
area followed by industrial area and commercial area. The concentrations of Fe, As, Ni and Mn were found to be more compared
to other metals. Further, the concentrations of all the heavy metals were higher in pre-monsoon (extended summer) and monsoon
followed by post-monsoon, autumn and winter. Meteorology played an important role in concentration of heavy metals in RSPM.
Turbulent conditions resulted in higher concentration owing to re-suspension and external input whereas, low wind speed, low
temperature and high relative humidity favoured low concentration of the pollutants. The evaluation of enrichment factor revealed
that Pb, As, Ni, Cu, and Mn are emitted, chiefly from anthropogenic sources and Fe and Mg are associated with natural sources. 相似文献
307.
Reduced nitrogen has a greater effect than oxidised nitrogen on dry heathland vegetation 总被引:2,自引:0,他引:2
van den Berg LJ Peters CJ Ashmore MR Roelofs JG 《Environmental pollution (Barking, Essex : 1987)》2008,154(3):359-369
We investigated the effects of different ratios of reduced (NH4+) versus oxidised (NO3(-)) nitrogen in deposition on heathland and species-rich grassland vegetation at high nitrogen deposition levels in large mesocosms filled with nutrient-poor soils to which different NH4+/NO3(-) ratios were applied. The response of the forbs, Antennaria dioica, Arnica montana, Gentiana pneumonanthe, Thymus serpyllum, the grasses Danthonia decumbens, Deschampsia flexuosa, Nardus stricta and the shrub Calluna vulgaris was recorded. The forb A. dioica and the grass D.decumbens preferred low NH4+/NO3(-) ratios and were characterised by a negative correlation between NH4+/NO3(-) ratios and biomass and survival, whereas the grasses N. stricta and D. flexuosa showed no correlation with NH4+/NO3(-) ratios. Lime addition eliminated the negative effects of high NH4+ concentrations in deposition for A. dioica and the grass D. decumbens. The implications of these findings for heathland vegetations are discussed. 相似文献
308.
Andrew J. McElrone Jason G. Hamilton Mihai Aldea Evan H. DeLucia 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):108-114
Atmospheric CO2 concentrations are predicted to double within the next century and alter climate regimes, yet the extent that these changes will affect plant diseases remains unclear. In this study conducted over five years, we assessed how elevated CO2 and interannual climatic variability affect Cercospora leaf spot diseases of two deciduous trees. Climatic data varied considerably between the five years and altered disease expression. Disease incidence and severity for both species were greater in years with above average rainfall. In years with above average temperatures, disease incidence for Liquidambar styraciflua was decreased significantly. When significant changes did occur, disease incidence and severity always increased under elevated CO2. Chlorophyll fluorescence imaging of leaves revealed that any visible increase in disease severity induced by elevated CO2 was mitigated by higher photosynthetic efficiency in the remaining undamaged leaf tissue and in a halo surrounding lesions. 相似文献
309.
310.
通过对粤湘赣交界处大东山花岗岩体及其上发育的风化土壤进行野外地质调查、主微量元素和铊(Tl)形态含量分析研究,初步揭示华南花岗岩风化成土过程中Tl的迁移富集规律。研究结果表明:(1)大东山花岗岩及其风化土壤的Tl含量明显超出我国和世界自然土壤Tl含量背景值(~1 mg/kg),证实研究区土壤普遍存在Tl富集现象;(2)风化壳样品组分与花岗岩具有很好的地球化学继承性,是大东山花岗岩原位风化的产物,且母岩成分相对均一;(3)Tl主要为残渣态(> 75%),且Tl与Rb和K具有良好的正相关性,说明风化壳花岗岩和土壤中Tl分别主要存储在含钾硅酸盐矿物(黑云母和钾长石)和粘土矿物(如伊利石)晶格中;(4)质量迁移系数表明Tl在风化壳剖面上层被淋滤出,向下迁移,随后在淀积层发生沉淀、富集;(5)母质C层土壤中残渣态Tl含量与花岗岩相似,但占比明显低。因此,在花岗岩风化成土过程中,伴随着含钾原生矿物的分解,Tl可被释放到风化壳地表环境中进而富集,形成华南花岗岩地区土壤Tl富集现象,对区域土壤质量安全的影响值得关注。 相似文献