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近年来,Staub和Cohen（1979）、Kra-vits等（1981）、Taylor等（1981）详细地研究了煤层中非煤夹层的成因和形态、古河道对泥炭沼泽的冲刷、侵蚀以及潮道的影响等。这些研究有助于确定煤层厚度变化速度及相对连续性,并用来预测厚煤远景区和可采界限,使开采效率更高。实际上,这种研究也是对成煤模式研究的重要补充。 相似文献
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煤层的很多参数,如煤层厚度变化、连续性、煤中硫分、灰分和痕量元素的含量以及煤层顶底板岩石开采技术条件和瓦斯含量等,是煤田勘探中评价煤矿床的重要因素,也是矿山设计和矿井开发中最关心的问题。若在煤田地质勘探期间,就能在一定程度上预测这些参数和煤层特征及其变化趋势、最有远景的可供开采地区及开采中可能遇到的种种问题,这样,不但解决了地质勘探和矿井开发中的实际问题;而且也可指导勘探和开采,大大地提高经济效益。 相似文献
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作为形成于特提斯和东部亚特提斯海盆上的世界最大的内陆咸水湖里海 ,多年来已引起研究工作者极大的兴趣。里海东南部的海湾是研究最差的海区 ,对它的研究进行得最不正规和最不系统。对这个海湾产生兴趣是因为没有河流注入的这些海湾最完整地反映了里海盆地的海平面升降机制。本文对土库曼湾的沉积条件进行了研究 ,并在原有方法的基础上利用古生态资料 ,试图确定近百年来底栖生物群落的变化。沉积层的测年是在里海—亚速海盆外来种群剖面分布基础上进行的 ,而它们的进入时间为已知。对深达０．４５ｍ的表层沉积物采用了肉眼和镜下研究 ,然后… 相似文献
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Ramos-Gómez J Martins M Raimundo J Vale C Martín-Díaz ML DelValls TA 《Marine pollution bulletin》2011,62(7):1538-1549
Sediment toxicity assessments using caged organisms present advantages over using laboratory and native community studies. The use of caged Arenicola marina in sediment toxicity assessments was evaluated. Lugworms were exposed in situ to sediments from coastal and port areas in Spain for seven days, and the activities of the biotransformation enzymes ethoxyresorufin O-deethylase, dibenzylfluorescein dealkylase and glutathione S-transferase, the activities of the antioxidant enzymes glutathione reductase and glutathione peroxidase and lipid peroxidation were then analyzed as biomarkers. Biomarker results and sediment physicochemical data were integrated. Cádiz Bay (SW Spain) sediments presented metal contamination that was not linked to a biochemical response. In LPGC Port (SW Spain), Pb contamination exhibited a moderate toxic potential, while PAHs, and presumably pharmaceuticals, provoked biochemical responses that efficiently prevented lipid peroxidation. In Santander Bay (N Spain), exposure to PAHs and, presumably, pharmaceuticals induced biomarker responses, but lipid peroxidation occurred nevertheless. These results indicated that caged A. marina were effective for the assessment of sediment quality and that the selected biomarkers were sufficiently sensitive to identify chemical exposure and toxicity. 相似文献
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Sea urchin embryo-larval development (ELD) and fertilization tests have been widely used in ecotoxicity studies and are included in regulatory frameworks. Biological processes occur naturally within a range of salinity that depends on the species considered. In an attempt to determine the optimum range of salinity, ELD and fertilization bioassays were performed at different salinities (15-40.5‰) with two species of Atlantic sea urchin: Arbacia lixula and Paracentrotus lividus. In the ELD assay, the optimum range of salinity was wider for A.?lixula (29-35.5‰) than for P.?lividus (29-33‰). In the fertilization assay with P.?lividus as a bioindicator species, the highest percentage of fertilization (90%) was obtained at salinities of between 29 and 33‰. More research on A.?lixula is required, since the fertilization success was below 60%. The results of the present study demonstrate that salinity may be a confounding factor in interpreting ELD test results. 相似文献
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Natural attenuation of septic system nitrogen by anammox 总被引：1，自引：0，他引：1
Robertson WD Moore TA Spoelstra J Li L Elgood RJ Clark ID Schiff SL Aravena R Neufeld JD 《Ground water》2012,50(4):541-553
On-site disposal of sewage in septic systems can lead to groundwater plumes with NO(3)(-)-N concentrations exceeding the common drinking water limit of 10 mg/L. Currently, denitrification is considered as the principal natural attenuation process. However, at a large seasonal-use septic system in Ontario (256 campsites), a suboxic zone exists where nitrogen removal of up to 80% occurs including removal of NH(4)(+)-N. This zone has both NO(3)(-)-N and NH(4)(+)-N at >5 mg/L each. In the distal NH(4)(+)-rich zone, NH(4)(+)-N concentrations (8.1 ± 8.0 mg/L) are lower than in the proximal zone (48 ± 36 mg/L) and NH(4)(+)-N is isotopically enriched (concentration-weighted mean δ(15)N of +15.7‰) compared to the proximal zone (+7.8‰). Furthermore, δ(15)N-NH(4)(+) isotopic enrichment increases with depth in the distal zone, which is opposite to what would result if nitrification along the water table zone was the mechanism causing NH(4)(+) depletion. Bacterial community composition was assessed with molecular (DNA-based) analysis and demonstrated that groundwater bacterial populations were predominantly composed of bacteria from two Candidatus genera of the Planctomycetales (Brocadia and Jettenia). Together, these data provide strong evidence that anaerobic ammonium oxidation (anammox) plays an important role in nitrogen attenuation at this site. 相似文献
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洋中脊正断层的几何形状Ｔ．Ａ．Ｍｉｎｓｈｕｌ等正断层在缓慢扩张的洋中脊轴部地形中有重要意义,也是确定深海丘陵形态的主要因素。微震和远震的证据表示存在延伸到地壳和上地幔中中等倾角（３０°～６０°）的洋中脊断层（Ｔｏｏｍｅｙ等,１９８５）。从潜水器中已发... 相似文献