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212.
Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) extracted by Soxhlet extraction (S-PAHs) with dichloromethane and routine accelerated solvent extraction (A-PAHs) with 1:1 toluene/methanol, respectively, were investigated in 24 soil samples from two cities in the center of the Pearl River Delta, South China. Polycyclic aromatic hydrocarbons, methylphenanthrene and perylene, in two soils, two sediments, and an immature oil shale were also sequentially extracted by accelerated solvent extraction (ASE) with each of four different organic solvents for three times. The A-PAHs' concentrations are 2.41 times the S-PAHs' concentrations. For sequential three ASEs, PAHs in the first extract account for 56 to 67% of their total concentrations in the sequential three extractions and toluene displays the best extraction performance among the four solvents. Diagnostic ratios of PAHs in Soxhlet extraction, routine ASE, and sequential ASE with each solvent for a given sample are very similar, suggesting their identical petrogenic and pyrogenic sources in the soils and sediments. But the PAH ratios for the shale have an obvious petrogenic origin. The perylene/5-ring PAH ratios indicate a diagenetic source, especially in the shale and sediments. The correlation analysis shows that A-PAHs/S-PAHs is better associated with the contents of total organic carbon (TOC) than those of black carbon (BC). The above results indicate the significant petrogenic origin of PAHs and the important effect of organic matter on their extraction and distribution in the investigated field soils/sediments. 相似文献
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基于遥感技术的长江三角洲海岸带生态系统服务价值评估 总被引:2,自引:0,他引:2
长三角海岸带是长江三角洲与东海间的重要过渡性区域,基于联合国千年评估提出的生态系统服务框架,以生态学为原理、以遥感反演技术为手段、借助经济学方法,对2005年及2008年长三角海岸带的10项生态系统服务价值进行了评估。结果表明,长三角海岸带2005及2008年的生态系统服务总价值分别为1 235.92、1 493.04亿元,与长三角地区实际GDP对比得出,生态系统服务价值实际降低,海岸带生态环境退化;对于不同的生态系统来说,林地、耕地、湿地的生态系统服务价值较高,为增强生态系统可持续发展应重点加以保护;对于不同的生态系统服务功能来说,旅游娱乐服务、土壤保持、调节水源为价值量最大的3项服务,而调节空气质量、精神文化服务、养分循环为价值量最小的3项服务。 相似文献
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Occurrence of veterinary antibiotics in animal wastewater and surface water around farms in Jiangsu Province, China 总被引:7,自引:0,他引:7
The objective of this investigation was to obtain a broad profile of veterinary antibiotics residues in animal wastewater and surface water around large-scale livestock and poultry farms in Jiangsu Province of China. Therefore, 53 samples collected from 27 large-scale animal farms in 11 cities and counties of Jiangsu Province in 2009, were monitored for 10 selected veterinary antibiotics using solid phase extraction and high performance liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) techniques. Ten veterinary antibiotics were found in animal wastewaters, eight antibiotics were detected in pond waters, and animal farm-effluents and river water samples were contaminated by nine antibiotics. The most frequently detected antibiotics were sulfamethazine (75%), oxytetracycline (64%), tetracycline (60%), sulfadiazine (55%) and sulfamethoxazole (51%) which were detected with a maximum concentration of 211, 72.9, 10.3, 17.0 and 63.6 μg L−1, respectively. The maximum concentration of 0.55 μg L−1 for cyromazine, 3.67 μg L−1 for chlortetracycline, 0.63 μg L−1 for sulfadoxine, 39.5 μg L−1 for doxycycline and 0.64 μg L−1 for sulfaquinoxaline were determined in the collected samples. In general, the maximum concentration of the selected veterinary antibiotics was detected in animal wastewaters except for chlortetracycline in animal farm-effluents. In addition, residue levels of selected veterinary antibiotics in animal wastewater and surface water around the farms were related to animal species and have a high spatial variation. 相似文献
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人工湿地中抗生素抗性大肠杆菌和抗性基因的去除与分布 总被引:1,自引:0,他引:1
抗生素的滥用导致抗生素抗性菌和抗性基因随生活污水和养殖废水的排放在环境中肆意散播,其去除及环境行为越来越受到关注。采用K-B纸片法测定了9套不同工艺构型模拟人工湿地中大肠杆菌对7种抗生素的抗性率,并应用多重PCR检测磺胺类sul1、2、3与四环素tetA、B、C、D抗性基因,探究人工湿地对抗性菌的去除效率及抗性菌、抗性基因的分布规律。结果显示,人工湿地能有效去除污水中70%左右的抗性大肠杆菌,有效降低了细菌抗性的传播风险;共计分离出535株大肠肝菌中有378株对一种以上抗生素有抗性性,以四环素、磺胺类和氨苄西林抗性率最高,达到25%以上,其他4种抗性率较低,不足20%;2种抗性基因的检出率都在70%以上;对不同采样点大肠杆菌的抗性性及抗性基因的比较发现,各部分大肠杆菌的抗性水平、多重抗性指数(MRI)以及抗性基因(sul、tet)检出率和组合数表现出:基质≥出水>进水,推测抗性菌被湿地基质截留,在基质生物膜上发生抗性基因的重组,并释放抗性菌,提高了出水中抗性水平和抗性基因检出率。 相似文献
220.
This paper examines the complex social reality of mixed ethnic residential areas, as reflected in drawn perceived neighbourhoods of Jews and Arabs living in homogenous and mixed neighbourhoods in Jaffa, Tel Aviv. Through in-depth interviews conducted among 89 Jaffa's residents, it illustrates how different perceptions about the residential area and its residents (including attitudes, emotions, feeling of fear/safety, collective identity and tolerant relations) are reflected in the form, size and consensus area of residents' perceived neighbourhoods. The study finds a clear association between tolerant attitudes and the size and consensus area of the perceived neighbourhoods. Arabs perceive their neighbourhood as significantly larger than Jews do and are characterised by a larger consensus area. These findings are explained by the Arab's strong social cohesion, common national identity, rootedness in Jaffa, as well as by tolerant attitudes towards Jaffa's Jewish population. The study demonstrates the interrelation between the spatial, social and perceptual dimensions associated with the mixed residential area, and illustrates how these dimensions are reflected in drawn perceived neighbourhoods. 相似文献