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1.
To prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. Plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. The objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits. Root penetration into layers of various sealing materials, such as clayey moraine (clay, 8-10%; silt, 22-37%; sand, 37-55%; gravel, 15-18%), moraine (unspecified), 6-mm bentonite (kaolin clay) fabric, lime and clay, Cefyll (mixture of pulverized coal fly ash, cement and water) and a mixture containing biosludge (30-35%) and bioashes (65-70%), was investigated. In the field, roots were studied by digging trenches alongside vegetation growing in 3- and 10-year-old mine sites. In the greenhouse root growth of Betula pendula, Pinus sylvestris, Poa pratensis and Salix viminalis were studied in compartments where the plants had been growing for 22 months. The results from the field experiment indicated that roots are able to penetrate both deep down in the cover layer (1.7 m) and also into the sealing layers of various materials, and even to penetrate hard Cefyll. The addition of nutrients in the top cover reduced deep root growth and thereby also penetration through the sealing layer. Low hydraulic conductivity of the sealing layer or a thick cover layer had less effect on root penetration. In the greenhouse experiment roots did not penetrate the thin bentonite fabric, due to low pH (2.1-2.7) that was created from the underlying weathered mine tailings. The clayey moraine was penetrated by all species used in the greenhouse experiment; Pinus sylvestris had the greatest ability to penetrate. To prevent root penetration of the other sealing layer, a suitable condition for the plants should be created in the upper part of the cover layer, namely a sufficient amount of plant nutrients. However, to define such a condition is difficult since different plant species have different requirements. 相似文献
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Cardiac anomalies may occur in isolation or can be part of a genetic syndrome. In this article, we describe some of the genetic syndromes commonly associated with cardiac anomalies where there are other sonographic features that may aid accurate prenatal diagnosis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Paul Uvebrant Eva Björck Nils Conradi Klas-Henry Hökegård Tommy Martinsson Jan Wahlström 《黑龙江环境通报》1993,13(7):651-657
A family with two siblings, 10 and 8 years old, both with clinical and ultrastructural evidence of juvenile neuronal ceroid lipofuscinosis is described. The family was found to be informative for the restriction fragment length polymorphisms (RFLPs) detected by the probes pCJ52–95Ml (locus D16S148) and pCJ52-94Tl (locus D16S159) flanking the juvenile neuronal ceroid lipofuscinosis locus, CLN3. The parents were both heterozygous using these probes, while their two children with juvenile neuronal ceroid lipofuscinosis were both homozygous. Chorionic villi analysis showed that the fetus was heterozygous and had inherited the one allele of the mother which was not found in the two siblings. This suggested that the fetus had derived one healthy allele from the mother, the risk for a double crossing-over being less than 1 per cent. Electron microscopy showed no fingerprint inclusions in chorionic villi. The child was investigated at 6 months of age and found to be healthy, as new fingerprint inclusions were found at electron microscopy and no vacuolated lymphocytes were found in the blood smear. Due to the risk of heterogeneity, both DNA-based analysis and electron microscopy on chorionic villi are recommended for prenatal examination for juvenile neuronal ceroid lipofuscinosis. 相似文献
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Per Nyberg Eva Bergstrand Erik Degerman Olof Enderlein 《Ambio-人类环境杂志》2001,30(8):559-564
通过对瑞典维纳恩、韦特恩、梅拉伦和哈马伦四大湖泊中上层鱼类种群生物学的研究得出,适宜区域里鱼苗在生长季节尽早孵化,并在冬季到来之前达到一定的体长,对鱼苗的成活是至关重要的.一般认为,这不仅是为了适应春季浮游动植物的生长,同时也是为了避免被捕食.相对于秋季产卵的欧白鲑(Coregonus albula)来说,通过对春季产卵的胡瓜鱼(Osmerus eperlanus)和梭鲈(Stizostedion lucioperca)的研究,我们更容易得出上述的结论.冰融之后欧白鲑苗的迅速孵化对鱼类的种群生长较为有利.在贫营养性、掠食性鱼类很少的湖泊中,冰融化之后水温的快速回升对种群的补充较为有利,而在富营养性的湖泊中,由于存在被捕食的压力,情况就大不一样了.研究结果表明秋季产卵群体较难适应全球变暖的趋势,不同年份鱼类在年种群生长强度方面存在着较大的差异,这可用生活史来予以解释. 相似文献
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本研究的目标是增加关于模型生成数据被用作水质管理的交流工具时,地方利益相关者接受该数据的知识.研究地区选在瑞典西南部的伦讷(R(o)nne(a))河流域.结果表明,模型生成数据起到了联合因素的作用.同时,利益相关者与提供的数据有关,主要问题为未考虑到的污染源、测定污染时缺乏信任、自然变化和延迟效应的影响的不确定性.确定了4组影响利益相关者接受模型生成数据的因素对其实际应用的信心,对所涉及的参与人员或对话资料提供者(如专家、决策者、媒体)的信心,参与者的社会特征(如年龄和职业),和数据的交流方式(如交流的语气、小组的构成、持续时间、对话的地理尺度).对给定的模型生成数据实际应用的公平性的感知,也是接受与否的一个重要因素. 相似文献
9.
退化的半干旱农业生态系统土壤碳的积累--危险和潜力 总被引:4,自引:0,他引:4
Lennart Olsson Jonas Ardo 《Ambio-人类环境杂志》2002,31(6):471-477
<京都议定书>意味着新的可能性:人类将把生物圈作为碳库进行管理.无论从环境还是社会经济的观点来看,把农业生态系统作为碳库是最合适可行的.非洲地区退化的生态系统显著受益于土地管理的改善(碳积累计划的一部分).在非洲有大面积的这样的农业生态系统,对它们的恢复是一个亟待解决的问题.我们同意UNEP的观点:<气候变化公约>、<联合国防治沙漠化公约>以及<联合国生物多样性公约>相互之间将会产生潜在而重要的促进作用.我们调查了苏丹半干旱农业生态系统土壤碳含量增加的潜力,发现延长休耕期将使土壤碳增加,而农业边缘区转变成牧场后碳储量将在100年内恢复到天然萨王纳的80%.碳增汇带来的经济收益将会对这些农业生态系统的家庭经济产生显著的贡献. 相似文献
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Environmental Science and Pollution Research - Traditional medicine (TM) also known as folk medicine consists of medical knowledge systems that were developed over generations in various countries... 相似文献