分层开采工艺对地表沉降的影响研究

分层开采是厚煤开采的经典工艺,这种工艺对地表沉降的影响比较复杂。通过测试原岩物理力学参数,利用有限元软件flac3D对分层和一次采全高时地表沉降进行了数值模拟。结果表明,如果采高较小,砌体梁距煤层较近,且采完上分层后长时间停采,给顶板再生留足时间,分层开采较一次采全高对地表沉降影响要小。     

Stability of a Coal Waste Artificial Reef

The feasibility of using U.K. coal-fired power station waste materials for artificial reef production is being examined. in June, 1989, an experimental artificial reef was constructed in Poole Bay, off the central south coast of the U.K., using three different mixtures of pulverised fuel ash (PFA), flue gas desulphurisation (FGD) gypsum and slurry, stabilized with cement and formed into blocks. Fifty tonnes of 40 × 20 × 20 cm blocks were formed into eight conical reef units replicating three different PFA/gypsum mixtures and one concrete control. the reef structure is 10m below chart datum on a flat sandy sea-bed.

Combustion of coal concentrates the heavy metal content in the resultant ash. the purpose of stabilization of the ash as blocks is twofold: to immobilize heavy metals (or other components) and to provide hard substratum for the attachment of organisms. to examine the effectiveness of this stabilization and hence the environmental compatibility of the block materials, heavy metal (Cd, Cr, Cu, Pb, Mn, Ni, Zn) content of the blocks has been monitored routinely over two years, to determine leaching rates. Sectional profiles indicate partial replacement of calcium content by magnesium. Associated with this there has also been some redistribution of heavy metals. Only in the case of cadmium has there been a detectable loss from the surface of blocks. Chromium and manganese concentrations appear to have increased. the metal content of the reef epibiota (including ascidians, Ascidia mentula; hydroids, Halecium spp.; bryozoans, Bugula spp. and red algae) growing on the ash blocks has been compared to that of epibiota attached to the concrete controls and surrounding sea-bed. to date no evidence of excess bioaccumulation of metals has been detected.

The physical integrity of the ash reef blocks has been maintained. There is evidence that the blocks are increasing in compressive strength.

An indication of the fishery enhancement potential of the experimental structure is given by the presence of eight commercially fished species (crustaceans and molluscs) including lobsters (Homarus gammarus).     

滇池鲤鱼的背景元素调查

通过滇池鲤鱼与松花坝水库和国内外同类鲤鱼的元素含量对比,确认滇池鲤鱼受工业污水的危害影响主要是As、Se。鱼体As、Se含量目前已经超过正常值,Ni、Cr、Cu、Fe、Pb比正常值偏低,其它元素属正常值范围。为了避免过多的元素富集,建议滇池鲤鱼以半年到一年为生长捕捞期为宜。     

基于有限元分析的橡胶减振器优化设计

目的加快橡胶减振器的设计过程。方法分析橡胶材料及Mooney-Rivllin橡胶本构模型特点,介绍橡胶减振器应用特点及隔振设计的相关理论,采用Mooney-Rivllin模型模拟橡胶材料的力学特性,通过引进有限元优化技术,在设计初期保证减振器的刚度特性。结果在某设备减振设计中,采用单轴拉压曲线获取了橡胶材料的Mooney-Rivllin模型参数,以减振器的部分结构尺寸为设计参数,减振器的三向刚度为设计目标,获取了三轴向频率近似相等的隔振系统(轴向频率40 Hz、径向频率40.9 Hz)。通过试验测试,减振系统频率与试验值差别较小,其中轴向差别为2%,径向差别为1%。结论通过引进有限元优化技术,采用合理的橡胶本构模型,可以满足工程精度要求,加速了橡胶减振器的设计过程。     

黔西南喀斯特地区红色风化壳的物源及元素迁移特征

南方喀斯特地区广泛分布着大量的红色风化壳,其成因及形成机制目前还存在争议。本文以贵州黔西南布依族苗族自治州泥凼石林的两处红色风化壳剖面(ND和YK)为研究对象,来探讨风化剖面上覆红土的物源问题,并计算其主、微量元素及稀土元素的迁移规律,认为本研究两处风化壳上覆红土为下伏基岩原位风化形成的,而且两剖面土壤均继承各自基岩的地球化学特征,并由于pH、风化强度等因素的影响表现出了元素迁移特征上的差异性。     

螯合树脂在线富集——火焰原子吸收光度法测定水中微量Cu,Pb,Zn,Cd

对螯合树脂在线富集，火焰原子吸收光度法进行了条件试验。试验证实方法对Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ４个元素检出浓度可达μｇ／Ｌ级，校准曲线性、样品重现性及准确度可满足测定要求。     

Trace Metal Concentration in Roadside Surface Soil and Tree Back: A Measurement of Local Atmospheric Pollution in Abuja, Nigeria

Cadmium, copper, lead, nickel and zinc concentrations were analysed by atomic absorption spectrophotometry in surface soil and tree bark from different districts of Abuja, Nigeria, in order to determine the atmospheric trace metal input in the area.Elevated concentrations of some of the studied metals were observed in the soil and tree bark samples from the commercial/high traffic areas of the city compared to backgroundvalues. In soil samples, the average concentration of the metals were 0.6±0.4, 18.0±4.0, 281±39, 16±4 and66±23 g g^-1 dry weight for Cd, Cu, Pb, Ni and Zn, respectively, whilst the average concentrations in tree bark were 0.3±0.2, 12±4, 133±32, 13±3 and 61±10 g g^-1 dry weight for Cd, Cu, Pb, Ni and Zn, respectively. The trend in trace metal levels suggested that automobile emissions are a major source of these metals as the highest concentrations of Pb and Zn were recorded in the commercial areas of the city known for their high traffic densities. The levels of metal in the study area were relativelylow compared to levels found in some larger and older cities in various countries worldwide.     

The Chemistry of Soils, Rocks and Plant Bioindicators in Three Ecosystems of the Holy Cross Mountains, Poland

In June of 2000, biogeochemical study was carried out in three ecosystems of the Holy Cross Mountains (south-central Poland). This paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil profiles, and plant bioindicators including epiphytic lichen Hypogymnia physodes (L.) Nyl., mosses (Pleurozium schreberi (Brid.) Mitt., Hypnum cupressiforme Hedw. S. Str., Hylocomium splendens (Hedw.) B.S.G.), Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth.), aspen (Populus tremula L.) and English oak (Quercus robur L.). Chemical analyses were performed with ICP-AES and AAS methods in the accredited laboratory (Central Chemical Laboratory of the Polish Geological Institute in Warsaw). The principal objective of this study was to compare the chemical composition of rocks, soils and selected plant bioindicators between investigation sites using the same methods of sample collection, preparation and analyses. The results of this study have shown that there is a high variability in concentrations of elements in plant bioindicators from the same sites that can not be explained only by soil properties or anthropogenic influence. This conclusion indicates that for biomonitoring purposes (especially with vascular plants) we cannot neglect individual features of the species examined.     

Bioindicator organisms: Heavy metal pollution evaluation in the Ionian Sea (Mediterranean Sea—Italy)

Trace metal concentrations of mercury, cadmium, lead and chromium in Patella caerulea, and Mullus barbatus were investigated to provide information on pollution of Ionian Sea, since these metals have the highest toxic potential. High chromium levels (0.47–0.97 g g^–1 ww) were registered in limpet samples collected from two station near the Gulf of Taranto, while elevated concentration of mercury (0.31–1.50 g g^–1 ww) were found in mullet specimens from Sicily. The metal concentrations recorded at the clean stations may be considered as useful background levels to which to refer for comparison within the Mediterranean area. On the contrary, the high levels of chromium and mercury found respectively in the areas near the Gulf of Taranto and at Capo Passero being of concern in terms of environmental health need frequent monitoring.     

A Survey of Trace Metals in Vegetation, Soil and Lower Animal Along Some Selected Major Roads in Metropolitan City of Lagos

The concentration of trace metals (Cd, Cu, Pb and Zn) in a total of 144 samples of grass, soil and lower animal (earthworm, Lybrodrilus violaceous) were collected and analysed for their metallic content. Levels of cadmium ranged from 0.01–0.07 g g^–1; 0.01–0.12 g g^–1 and from trace–0.05 g g^–1 dry weight for plant, soil and animal samples respectively. Mean concentration of copper ranged 0.10–1.48 g g^–1; 0.10–2.90 g g^–1 and 0.01–0.08 g g^–1 for samples in similar order as above. The levels of Pb varied from 0.01–0.14 g g^–1; 0.02–0.23 g g^–1 and from trace–0.07 g g^–1 while that of Zn ranged from 0.19–1.80 g g^–1; 0.51–3.35 g g^–1and 0.01–0.08 g g^–1 also in the same order of samples as mentioned above. Levels of metals in soil samples were higher than the background levels with the exception of Zn but lower than European Union (EU) limits. The results generally revealed the presence of metals in plant and animal samples and metal dynamics up the food chain is highly possible. Acceptable recoveries of the spiking experiment validate the experimental protocol.