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191.
水环境中耐热大肠菌群的抗生素耐药性与质粒谱研究 总被引:5,自引:0,他引:5
用滤膜法、mFC培养基从5种水体中分离出疑似耐热大肠菌162株,用API微生物分析系统鉴定到种,以Kirby-Bauer法分析其对人畜常用10种抗生素的耐药性,碱裂解法小量制备各菌株质粒DNA做质粒谱分析.结果表明,埃希氏大肠杆菌为优势菌,占分离菌总数的96.3%.除分离自泉水的3株外,其它菌株都对3种及3种以上抗生素耐药,多重耐药率为98.1%.不同水体分离菌株对氧氟沙星、诺氟沙星、庆大霉素、丁胺卡那霉素、链霉素的耐药率有显著性差异(P<0.005).92株菌(56.8%)提取到大小为0.90~158.83kb、数量为1~6个的质粒,有81种质粒谱型.70株(43.2%)未提取到质粒的细菌中有67株为多重耐药.具有相同质粒谱型的菌株耐药谱都不相同.未发现质粒谱与抗生素耐药性间有明显相关性.图1表3参15 相似文献
192.
本文通过对赤水紫色森林土壤发育特点的研究,总结出划分紫色森林土壤剖面的方法,解决了紫色森林土壤剖面划分不清楚,研究人员之间各自划分的结果不能对比的问题,为进一步研究紫色森林土壤打下了基础。 相似文献
193.
194.
采用流动式采样与气相色谱-质谱联用法研究了意大利撒丁岛Noak’s Ark自然生态区四种主要灌木树种Juniperus phoenicea(腓尼基桧),Pistacia lentiscus(黄连木),Phillyrea angustifilia,Chamaerops humilis(欧洲矮棕)的排放速率和排放特征。结果表明,JuniPerus phoenicea(腓尼基桧),Pistacia lentiscus(黄连本),Phillyrea angustifilia主要排放萜烯类化合物,其中包括α-蒎烯、β-蒎烯、苎烯、戊花烃、莰烯、β-水芹烯、桧烯、β-香叶烯和3-蒈烯等;Chamaerops humilis(欧洲矮棕)主要排放异戊二烯。在标准条件下(温度30℃,PAR为1000μmo1.m^-2.s^-1),四种树种的排放速率分别为0.15、2.10、0.20和1.87μg/g(DW).h。 相似文献
195.
Bobo Wu Tongran Wu Yangyang Cui Aiping Lian Ye Tian Renfei Li Xinyu Liu Jing Yan Yifeng Xue Huan Liu 《环境科学学报(英文版)》2023,35(2):513-521
Over the past decade, the emission standards and fuel standards in Beijing have been upgraded twice, and the vehicle structure has been improved by accelerating the elimination of 2.95 million old vehicles. Through the formulation and implementation of these policies, the emissions of carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxides (NOx), and fine particulate matter (PM2.5) in 2019 were 147.9, 25.3, 43.4, and 0.91 kton in Beijing, respectively. The emission factor method was adopted to better understand the emissions characteristics of primary air pollutants from combustion engine vehicles and to improve pollution control. In combination with the air quality improvement goals and the status of social and economic development during the 14th Five-Year Plan period in Beijing, different vehicle pollution control scenarios were established, and emissions reductions were projected. The results show that the emissions of four air pollutants (CO, VOCs, NOx, and PM2.5) from vehicles in Beijing decreased by an average of 68% in 2019, compared to their levels in 2009. The contribution of NOx emissions from diesel vehicles increased from 35% in 2009 to 56% in 2019, which indicated that clean and energy-saving diesel vehicle fleets should be further improved. Electric vehicle adoption could be an important measure to reduce pollutant emissions. With the further upgrading of vehicle structure and the adoption of electric vehicles, it is expected that the total emissions of the four vehicle pollutants can be reduced by 20%-41% by the end of the 14th Five-Year Plan period. 相似文献
196.
文章按照《制定地方大气污染物排放标准的技术方法》建立了蚕桑区大气氟化物允许排放速率牟模型,根据蚕桑区氟污染特征,污染危害特征和污染气象特征确定模型参数,提出了浙江省杭嘉湖蚕桑区大气氟化物排放标准,并分析了标准的经济和技术可行性。 相似文献
197.
西安城市交通干道汽车污染物排放因子 总被引:3,自引:0,他引:3
在西安城市交通隧道内设3 个空气监测点,对通过隧道的汽车排气形成的污染物浓度、隧道内风速、过往隧道的交通量进行采样、观测和统计。根据实测数据用大气扩散方程求得西安城市道路汽车平均单车 C O、 H C 和 N Ox 排放因子分别为33279 ±12158 、3577 ±1816 和4605 ±1981 mg/m·veh 。与国外的成果相比,中国城市道路汽车 C O 和 H C 排放因子分别是国外发达国家汽车排放因子的2 ~9 倍和3 ~9 倍,而中国城市汽车 N Ox 排放因子约为发达国家汽车排放因子的二分之一。 相似文献
198.
重庆城区机动车排放污染研究 总被引:5,自引:0,他引:5
通过调查研究首先弄清重庆城区主干道机动车排放污染的现状,算出机动车排污负荷在城区道路大气环境中的分担率,利用美国EPA推荐的MOBILES模型计算城区道路机动车排放的综合排放因子,由此估算重庆城区机动车排放总量并预测2005、2010年的发展趋势。 相似文献
199.
Huan Liu Yangwen Jia Cunwen Niu Yongde Gan 《Journal of the American Water Resources Association》2019,55(5):1349-1366
Water resources have become a barrier hampering socioeconomic development. Changes in the spatial distribution of water use profile have direct impacts to regional water use efficiency. However, the related research is inadequate, and a more suitable way to analyze regional water use profile is necessary. The Gini coefficient and location quotient, two reliable methods commonly used in discussing the spatial distribution of elements, were introduced and calculated. Taking Gansu Province as the study area, the concentration effect of industrial water use was the strongest, followed by domestic, environmental, and agricultural water use. However, a balanced distribution of agricultural water use failed to be coordinated with the production conditions, the center of Gansu’s grain production should be established to enhance the scale effect of agricultural production. The industrial agglomeration effect remained weak, and each region’s dominant industries need to be developed vigorously. Gansu’s domestic water use was consistent with its population distribution, but it is necessary to reduce the water use gap between urban and rural areas. With a growing awareness of environmental protection, environmental water use exhibited a more balanced distribution. Overall, the methods are simple and have good applicability, and the results can provide a reference in water use optimization. 相似文献
200.
Richao Wang Zibing Yuan Junyu Zheng Cheng Li Zhijiong Huang Wenshi Li Yan Xie Yiran Wang Kaiyang Yu Lejun Duan 《环境科学学报(英文版)》2020,32(10):138-150
Speciated characterization of Volatile Organic Compounds (VOCs), including oxygenated VOCs (OVOCs), from construction machinery and river ships in China is currently lacking. In this regard, we conducted field measurement on speciated VOC (including OVOC) emissions from six construction machinery and five river ships in the Pearl River Delta (PRD) region to identify VOC emission characteristics. We noticed that OVOC emissions from construction machinery and ships accounted for more than 50% of the total VOC emissions, followed by alkenes, aromatics and alkanes. Formaldehyde and acetaldehyde were the most emission species, accounting for 61.8%-83.2% of OVOCs. For construction machinery, the fuel-based emission factors of roller, grader and pile driver were 3.12, 3.12 and 7.36 g/kg, respectively. With the rigorous restraint by the national emission standards, VOC emissions of construction machinery had decreased considerably, especially during stage Ⅲ. Ozone formation potential was also significantly reduced due to the significant decrease in emissions of OVOCs and alkenes with higher reactivity. For river ships, the fuel-based emission factors of cargo ships and speedboat were 1.46 and 0.44 g/kg, respectively. VOC emissions from construction machinery and river ships in Guangdong Province in 2017 were 8851.0 and 4361.0 ton, respectively. This study filled the knowledge gaps of reactive gas emissions from different kinds of non-road mobile sources over the PRD, and more importantly, highlighted the necessity in adding OVOC measurement to give a complete and accurate depiction of reactive gas emissions from non-road mobile sources. 相似文献