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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
2.
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
3.
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
4.
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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7.
S. L. Holmberg T. Claesson M. Abul-Milh B. -M. Steenari 《Resources, Conservation and Recycling》2003,38(4):3071
At the district heating plant of Kalmar, Sweden an on-line unit for production of granulated wood ash for nutrient recycling on forest soils is being applied. Currently, the granules are dried by hot air from an oil-fired burner. The objective of this work was to investigate how drying by flue gas affects the hardening of granules, or impacts their chemical composition and properties. Ninety-six granule samples were treated by flue gas from natural gas combustion in a laboratory pilot scale flue gas generator. CO2, CO, O2, C3H8 and NO concentrations were varied during the experiment. Additionally, some samples were treated by flue gas from combustion of sawdust at the heating plant in Kalmar. Drying by flue gases did not affect the chemical composition of granules, but minor effects were seen in their mineralogy. The carbonate content was slightly higher in granules treated with flue gas from natural gas combustion compared to the granules dried by hot air only, when measured by wet chemical methods. Results from XRD analysis imply that the calcite content is higher and the portlandite and arcanite content slightly less in granules treated with flue gas from sawdust combustion compared to the granules dried by hot air only. The results from this investigation showed no negative effects on ash granule composition or physical structure by the use of a flue as a drying medium. 相似文献
8.
Adsorption of carbon dioxide on alkaline modified X zeolites was investigated by temperature programmed desorption (TPD) analysis of these materials previously saturated with CO(2) at 50, 100 and 200 degrees C. Parent X zeolite (in its sodium form) was treated with different sodium and cesium aqueous solutions, using both carbonates and hydroxides as precursors. The resulting materials were characterised by nitrogen physisorption, XRD, and NH(3)-TPD, in order to determine their morphological, crystallographic and chemical properties. Slight desilication phenomena were observed using hydroxides as precursors, whereas the treatment with Cs salts lead to higher crystallinity losses. Several successive adsorption-desorption cycles were carried out in order to check the regenerability of the adsorbents. Cesium-treated zeolites present higher carbon dioxide retention capacities than the sodium treated and than the parent material. When working with these Cs-modified materials, the desorption takes place mainly at temperatures between 250 and 400 degrees C, results of great practical interest, since it allows the use these kinds of materials for adsorption-desorption cycles. The evolution of the retention capacity with temperature is also markedly more positive for Cs-treated zeolite, especially when carbonate is used as the precursor. These materials maintain high retention capacities at 100 degrees C (10mg g(-1)) and even at 200 degrees C (3mg g(-1)), temperatures at which the most of the adsorbents are inactive. 相似文献
9.
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
10.
The fate of Norse farming settlements in southwest Greenland has often been seen as one of the great mysteries of North Atlantic colonization and expansion. Preservation of organic remains in the permafrost of the area of the Western Settlement, inland from the modern capital Nuuk, allowed very detailed study of the phases of occupation. Samples were taken from house floors and middens during the process of archaeological excavations and from insect remains were abstracted and identified in the laboratory. In this study, we present a new paleoecological approach principally examining the fossil fly faunas from house floors. The results of our study provide contrasting detailed pictures of the demise of two neighboring farms, Gården under Sandet and Nipaatsoq, one where abandonment appears as part of a normal process of site selection and desertion, and the other where the end was more traumatic. The level of detail, which was obtained by analysis of the dipterous (true fly) remains, exceeds all previous work and provides insights otherwise unobtainable. 相似文献