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991.
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Potential of different species for use in removal of DDT from the contaminated soils 总被引:3,自引:0,他引:3
Dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-DDD and p,p'-DDE (DDTs in this study included DDT, DDD and DDE), are frequently detected in agricultural soils even though its usage in agriculture was banned in 1980s or earlier. In this study, eleven plants including eight maize (Zea mays) cultivars and three forage species (alfalfa, ryegrass and teosinte) widely cultivated in China were grown in the soils spiked with DDTs to investigate their potential for removal of DDT from the contaminated soils. The plants varied largely in their ability to accumulate and translocate DDTs, with the bioconcentration factor (BCF; DDT concentration ratio of the plant tissues to the soils) ranging from 0.014 to 0.25 and the translocation factor (TF; DDT concentration ratio of the shoots to the roots) varying from 0.35 (Zea mays cv Chaotian-23) to 0.76 (Zea mays spp. mexicana). The amount of DDT phytoextraction ranged from 3.89mug (ryegrass) to 27.0mug (teosinte) and accounted for <0.1% of the total initial DDTs spiked in the soils. After 70d, the removal rates reached 47.1-70.3% of the total initial DDTs spiked in the soils with plants while that was only 15.4% in the soils without plant. Moreover, the higher removal rates of DDTs occurred at the first 20d of experiment, and then the removal rate decreased with time. The highest amount of DDTs phytoextracted was observed in teosinte, followed by Zea mays spp. mexicana, but the highest removal rate of DDTs was found in maize (Zea mays cv Jinhai-6). Even though phytoextraction is not the main removal process for DDTs, the plant species especially Zea mays cv Jinhai-6 showed high potential for removing DDTs from the contaminated soils. 相似文献
994.
采用K2FeO4预氧化-FeCl3混凝联合去除水中的As3+,考察了适宜的K2FeO4预氧化时间、Fe3+和Fe6+加入量,分析了预氧化pH、混凝pH、碳酸盐和腐殖酸浓度对该工艺去除As3+效果的影响.实验结果表明:K2FeO4预氧化的适宜时间为2 min;加入质量浓度为2.4 mg/L的Fe6+和14.0 mg/L的Fe3+能使处理后水样中的As3+浓度符合GB--57492006<生活饮用水卫生标准>(As3+质量浓度小于0.01 mg/L);预氧化pH在4~9范围内,对K2FeO4预氧化-FeCl3混凝去除As3+的效果影响不大;FeCl3混凝阶段适宜的pH为6.0~8.5.碳酸盐对K2FeO4预氧化-FeCl3混凝去除As3+的效果基本没有影响;腐殖酸的存在使As3+的去除率有一定程度的降低. 相似文献
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Zhang Q Li Z Zeng G Li J Fang Y Yuan Q Wang Y Ye F 《Environmental monitoring and assessment》2009,152(1-4):123-131
In the study, multivariate statistical methods including factor, principal component and cluster analysis were applied to analyze surface water quality data sets obtained from Xiangjiang watershed, and generated during 7 years (1994-2000) monitoring of 12 parameters at 34 different profiles. Hierarchical cluster analysis grouped 34 sampling sites into three clusters, including relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) sites, and based on the similarity of water quality characteristics, the watershed was divided into three zones. Factor analysis/principal component analysis, applied to analyze the data sets of the three different groups obtained from cluster analysis, resulted in four latent factors accounting for 71.62%, 71.77% and 72.01% of the total variance in water quality data sets of LP, MP and HP areas, respectively. The PCs obtained from factor analysis indicate that the parameters for water quality variations are mainly related to dissolve heavy metals. Thus, these methods are believed to be valuable to help water resources managers understand complex nature of water quality issues and determine the priorities to improve water quality. 相似文献
997.
高校宿舍火灾数值仿真模拟 总被引:4,自引:1,他引:3
高等院校的学生人数众多,住宿比较密集,存在不少安全隐患,宿舍火灾对学生的自身安全和财物安全构成重大威胁。宿舍灭火以及人员疏散的关键在于掌握火灾发生中的重要参数变化。笔者采用美国国家标准和技术研究院(NIST)开发的FDS(Fire Dynamic Simulator)软件,建立高校宿舍模型,对宿舍火灾进行全尺寸模拟。通过模拟实验给出了火灾发生过程中烟气运动、纵向温度变化和氧气浓度变化的规律,最后笔者提出一种有效的灭火防灾方案,并进行模拟和验证,为学校防火防灾决策提供有力的依据。 相似文献
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Fish tissues from different fishery types (freshwater farmed, seawater farmed and seawater wild) were analyzed for organochlorine pesticides (OCPs), with the aim to further our understanding of bioaccumulation, and reflect the state of different fishery environments. Significantly higher SigmaOCP levels were found in seawater farmed fish than others, and among three freshwater farmed species, the lowest levels occurred in filter-feeding fish (bighead carp). Liver contained the highest SigmaOCP levels, while no significant differences were found among other tissues. Among DDT components, p,p'-DDT was abundant in seawater fish, while for freshwater fish, p,p'-DDE was the predominant congeners, except for northern snakehead (34% for p,p'-DDE and 30% for p,p'-DDT). The new source of DDTs to freshwater fish ponds was partly attributed to dicofol, whereas sewage discharged from the Pearl River Delta and anti-fouling paint were likely the DDTs sources to seawater farmed fish. 相似文献