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851.
A strain Pandoraea pnomenusa LX-1 that uses dichloromethane(DCM) as sole carbon and energy source has been isolated and identified in our laboratory. The optimum aerobic biodegradation of DCM in batch culture was evaluated by response surface methodology. Maximum biodegradation(5.35 mg/(L·hr)) was achieved under cultivation at 32.8°C, pH 7.3, and 0.66% NaCl. The growth and biodegradation processes were well fitted by Haldane's kinetic model, yielding maximum specific growth and degradation rates of 0.133 hr-1and 0.856 hr-1, respectively. The microorganism efficiently degraded a mixture of DCM and coexisting components(benzene, toluene and chlorobenzene). The carbon recovery(52.80%–94.59%) indicated that the targets were predominantly mineralized and incorporated into cell materials. Electron acceptors increased the DCM biodegradation rate in the following order: mixed oxygen iron sulfate nitrate. The highest dechlorination rate was 0.365 mg Cl-/(hr·mg biomass), obtained in the presence of mixed electron acceptors. Removal was achieved in a continuous biotrickling filter at 56%–85% efficiency, with a mineralization rate of 75.2%. Molecular biology techniques revealed the predominant strain as P. pnomenusa LX-1. These results clearly demonstrated the effectiveness of strain LX-1 in treating DCM-containing industrial effluents. As such, the strain is a strong candidate for remediation of DCM coexisting with other organic compounds. 相似文献
852.
Tree species and temperature change arising from seasonal variation or global warming are two important factors influencing N2O and NO emissions from forest soils. However, few studies have examined the effects of temperatures(5–35℃) on the emissions of forest soil N2O and NO in typical subtropical region. A short-term laboratory experiment was carried out to investigate the influence of temperature changes(5–35℃) on soil N2O and NO emissions under aerobic conditions in two contrasting(broad-leaved and coniferous) subtropical acidic forest types in China. The results showed that the temporal pattern of N2O and NO emissions between the three lower temperatures(5℃, 15℃, and 25℃) and 35℃ was significantly different for both broad-leaved and coniferous forest soils. The effects of temperature on soil N2O and NO emission rates varied between broad-leaved and coniferous forest soils. Both N2O and NO emissions increased exponentially with an increase in temperature in the broad-leaved forest soil. However, N2O and NO emissions in the coniferous forest soil were not sensitive to temperature change between 5℃ and 25℃. N2O and NO emission rates were significantly higher in the broad-leaved forest soil as compared with the coniferous forest soil at all incubation temperatures except 5℃. These results suggest that the broad-leaved forest could contribute more N2O and NO emissions than the coniferous forest for most of the year in the subtropical region of China. 相似文献
853.
Bacterial diversity was investigated in soil samples collected from 13 sites around the Great Wall Station, Fildes Peninsula, King George Island, Antarctica, using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes. The classes α-, β-, and γ-Proteobacteria, as well as the phylum Actinobacteria, were found to be the dominant bacteria in the soils around the Great Wall Station. Although the selected samples were not contaminated by oil, a relationship between soil parameters, microbial biodiversity, and human impact was still seen. Sample sites in human impacted areas showed lower bacterial biodiversity (average H′= 2.65) when compared to nonimpacted sites (average H′= 3.05). There was no statistically significant correlation between soil bacterial diversity and total organic carbon (TOC), total nitrogen, or total phosphorus contents of the soil. Canonical correlation analysis showed that TOC content was the most important factor determining bacterial community profiles among the measured soil parameters. In conclusion, microbial biodiversity and community characteristics within relatively small scales (1.5 km) were determined as a function of local environment parameters and anthropogenic impact. 相似文献
854.
855.
汽车尾气对空气的污染越来越严重,影响人们的健康生活,破坏生态环境。机动车尾气中的氮氧化物是大气污染的主要污染物之一,采取有效措施减少机动车氮氧化物排放对于空气质量的改善具有重要意义。 相似文献
856.
中国以流域为单元实行的统一区域管理虽然已普遍被世界各国政府和学者接受,但在中国并没有形成一个具有统一职权和执行效力的跨区域水环境保护管理机构。以流域水资源管理为例,流域水资源保护机构名义上受水利部与环境保护部的双重领导,但在编制上却是水利部的派出事业单位,负责具体水污染管理事宜的环境保护部门的领导权在实际中并不容易落实。同时水利部和环保部门相应的受各级地方政府领导,其财政权和人事任免权由地方政府掌控,这种地位的不独立性容易使其行为受地方政府意志的支配。另外,在晋升激励和财政分税制的制度背景下,各流域地方政府有意愿和能力干涉环保部门的行为,使各种水环境保护事物让位和屈就于更实惠的地方经济发展。对于此种跨区域水环境保护行政管理体制现存的问题应当进行改善。 相似文献
857.
858.
Manwen Zhang Guixian Feng Wenhua Yin Bing Xie Mingzhong Ren Zhencheng Xu Sukun Zhang Zongwei Cai 《环境科学学报(英文版)》2017,29(12):3-10
Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans(PCDD/Fs) after stricter environmental regulations. PM_(2.5) and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/(kg·day), which far exceeded the tolerable daily intake(TDI) limit(1–4 pg TEQ/(kg·day). Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented. 相似文献
859.
通过理论计算和案例分析,对目前在用加油站油气回收系统的有效运行率进行了分析,阐述加油站三次油气回收装置的配备条件,介绍了加油站油气回收新技术(ORVR),提出了我国应使用新的加油站油气回收技术的结论。 相似文献
860.
Jun Li Aimin Li Yan Li Minhui Cai Gan Luo Yaping Wu Yechao Tian Liqun Xing Quanxing Zhang 《Frontiers of Environmental Science & Engineering》2022,16(4):47