共查询到19条相似文献,搜索用时 62 毫秒
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苔藓对大气沉降重金属元素富集作用的研究 总被引:10,自引:0,他引:10
利用超热电子活化法(ENAA)、原子吸收法(AAS)和原子荧光法(HG-AFS)测定了采自远郊和浙江西天目山自然保护区4个不同地点12种苔藓中19个重金属元素含量。结果表明,北京地区大气重金属沉降污染程度远高于浙江西天目山地区。与欧洲苔藓中重金属浓度比较,该12种苔藓偏高。经种间校正后的各种苔藓可互相替代作为生物监测器。 相似文献
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SRXRF研究苔藓植物对Pb/Fe/Cr污染的生物监视和累积特征 总被引:2,自引:0,他引:2
为研究苔藓植物对环境污染的累积特性和生物监视机理,用加入不同浓度的Pb、Fe、Cr培养基对二代扩繁后的小立碗藓进行胁迫试验,用同步辐射X射线荧光分析技术(SRXRF)测定藓体内金属元素含量,用微束荧光扫描技术(μ-SRXRF)分析了Cr、K等元素在苔藓叶和茎中的精细分布特征。结果表明,在单一重金属或复合重金属元素的胁迫下,藓体内污染金属元素的含量与培养基中相应元素的浓度呈现正相关,小立碗藓的受伤害程度随重金属元素浓度的增加而加重。重金属的胁迫导致小立碗藓吸收K、S等营养元素的能力急剧下降,且小立碗藓茎中K的吸收浓度由于受到过量Cr的拮抗作用而逐步降低。 相似文献
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为探讨石生苔藓硫同位素组成特征对区域性大气硫源的指示作用,连续两年采集鄱阳湖生态经济区内的石生苔藓样品,测定δ34S值;并结合已有的雨水、煤的硫同位素值等相关研究数据进行对比分析。样品δ34S值均偏正,平均为+4.9‰,取值范围为+1.9‰~+9.6‰;石生苔藓δ34S值与空气中SO2浓度呈负相关关系;南昌、抚州两市苔藓δ34S值的取值范围与其对应城市大气降水δ34S值的变化区间相接近;研究区内土壤相对富集重硫,且土壤中可溶性硫主要受大气硫沉降影响。结果表明,石生苔藓的硫同位素组成对区域性大气硫源具有指示意义,鄱阳湖生态经济区大气硫沉降的硫源主要来自人为成因硫和生物成因硫,可能还有远距离传输硫等其他硫源的影响。 相似文献
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本文叙述了染色体畸变分析作为生物剂量计的国内外研究概况。文中较详细地介绍了离体照射诱发染色体畸变的剂量-效应关系及其在事故受照人员剂量估算中的应用状况,对局部照射和分次照射条件下确定剂量-效应关系的有关问题进行了分析,对今后研究动向作了简要讨论。 相似文献
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辐射生物剂量计在核事故受照人员剂量估算及辐射生物效应研究中具有重要的作用,被视为"金标准"的染色体畸变分析不能满足大批量快速检测的要求.因此,找到更为快速、简便的生物剂量计成为放射生物剂量学的研究热点.研究发现,电离辐射能够诱导转录调节网络中的基因表达发生变化,有希望成为辐射生物剂量计.涉及较多的是p53通路相关基因,... 相似文献
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L.K. Boamponsem J.I. Adam B.J.B. Nyarko 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(9):1492-1501
In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area. 相似文献
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B. M. Clark N. F. Mangelson L. L. St. Clair J. S. Gardner L. S. Cooper L. B. Rees P. G. Grant G. S. Bench 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1999,150(1-4):248-253
In order to better understand the distribution pattern of mineral elements in lichen tissues, thin sections (15 μm) of the foliose, vagrant soil lichen Xanthoparmelia chlorochroa were examined using proton microprobe Particle induced X-ray emission (PIXE). This technique was used to make two-dimensional scans, with 5 μm resolution, across tissue cross sections of the test species. Element maps for Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and As have been prepared. Several elements are strongly localized in the element maps. PIXE data are complimented with STIM, light micrographs, and SEM images. Preliminary data suggest that nuclear microprobe techniques may be useful in elucidating element absorption and transport mechanisms in lichens. 相似文献
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M. Döbeli M. Mallepell A.M. Müller 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(24):3057-3059
Material removal induced by HIBS (Heavy Ion Backscattering Spectrometry) analysis has been investigated. For this purpose the thickness of thin metal films deposited on graphite was measured as a function of fluence of the Si and Ti projectile ion beam. Steady state erosion rates are in fair agreement with surface sputtering rates calculated by SRIM. For some layers however, the first few monolayers are removed at a much faster rate. A comparison with standard He RBS is made and consequences for the applicability of HIBS are discussed. 相似文献
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设计一套可以观测重金属运移的装置,实验发现:当重金属中加入U、Th等α放射源后,放射源的α衰变能够使重金属产生明显的向上运移,这是因为重金属与He核形成团簇,当团簇的密度比空气小时,重金属团簇便可以向上运移。 相似文献
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Progress in theoretical research into track structure and energy deposition distribution of heavy ions in introduced,and some research results are given,such as a Monte Carlo model of heavy ion track structure calculation,frequency distribution of energy deposition inside a electron track and radial dose distribution around a heavy ion path.Moreover,research direction in future is also analysed. 相似文献
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重离子束对牧草的改良 总被引:3,自引:0,他引:3
采用80MeV/u^20Ne^10 离子束贯穿处理豆科与禾本科牧草种子,大田和根尖细胞观测的结果表明,随着贯穿剂量的增加,幼苗生长明显减弱,呈负相关性。而染色体畸变率和微核率随剂量的增加而显著增加,呈正相关性。同时,从大田长势来看,禾本科牧草比豆科牧草对重离子辐射敏感性强,禾本科牧草适宜剂量为20-30Gy,豆科牧草为150Gy。 相似文献