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111.
Seismic noise induced by the seismic source during continuous profiling reduces the signal-to-noise ratio and hence the data quality. This noise is largely dependent on the shot interval. In this paper, the noise amplitude of refraction seismic records from a special experiment is analysed as a function of the shot interval. An empirical exponential relationship between mean peak noise amplitude and shot interval is deduced. By increasing the shot interval, the induced noise can be minimized on all successive records. This results in an improvement of the data, predominantly the signal-to-noise ratio. Because the seismic signal and the shot-induced noise have nearly the same spectra, the chance of improving the signal-to-noise ratio by stacking is significantly reduced. 相似文献
112.
113.
This study takes cognizance of the fact that the TIOMIN (TIOMIN Resources Inc. of Canada) project has resulted in controversy over its handling of environmental issues and especially the Environmental Impact Assessment (EIA). The authors address many of the protracted issues that have slowed the development of the mining project in Kwale. The main emphasis is on the impacts of the mining and mineral separation processes on the environment, including the governing legislation, the role of consultation and public participation, and socioeconomic issues. In their public documents TIOMIN has specified neither the type of minerals it wants to extract from the area nor their chemical composition. It is well known, however that the titanium minerals and zircon targeted have impurities of iron, thorium and uranium. In the absence of an Environmental Management Plan, the effects of stockpiling radioactive wastes and other impurities that could possibly lead to environmental degradation in both the terrestrial and marine environments have not been publically addressed. The measures proposed to mitigate ecological damage as a result of the establishment of a minerals processing plant in the area seem inadequate. Pollution resulting from accidental spillage or breakage could have significant impact on marine life and residents living near the mining site. Other issues that have not been addressed satisfactorily pertain to the use of surface and underground water. The area already faces a huge water deficit and the calculations presented on aquifer recharge and stream flow rates do not indicate the large quantities of water that would be required in the mineral processing plant. The project, if approved in its present state, risks violation of international conventions. Furthermore, it could cause a conflict between Kenya and Tanzania in the event of an oil spill at the proposed ship loading facility at Shimoni. The proposed mining area includes the district's most fertile land, is home to many fisherfolk and is a major tourist destination. An analysis of the effects of this project on other available opportunities must be thoroughly understood to ascertain the economic and environmental benefits and costs of the mining venture. The proposed compensation rate of $1,000 per acre, for resettlement for example, appears to be grossly inadequate. Compensation should take into account family size and structure family assets and the cost of relocation. 相似文献
114.
Naoto Ebuchi 《Journal of Oceanography》2006,62(2):171-183
Seasonal and interannual variations in the East Sakhalin Current (ESC) are investigated using ten-year records of the sea
level anomaly (SLA) observed by the TOPEX/POSEIDON (T/P) altimeter. The T/P SLA clearly documents seasonal and interannual
variations in the ESC along the east coast of Sakhalin Island, although sea ice masks the region from January to April. Estimates
of surface current velocity anomaly derived from T/P SLA are in good agreement with drifting buoy observations. The ESC is
strong in winter, with a typical current velocity of 30–40 cm s−1 in December, and almost disappears in summer. Southward flow of the ESC is confined to the shelf and slope region and consists
of two velocity cores. These features of the ESC are consistent with short-term observations reported in previous studies.
Analysis of the ten-year records of T/P SLA confirms that the structure of the ESC is maintained each winter and the seasonal
cycle is repeated every year, although the strength of the ESC shows large interannual variations. Seasonal and interannual
variations in the ESC are discussed in relation to wind-driven circulation in the Sea of Okhotsk, using wind stress and wind
stress curl fields derived from European Centre for Medium Range Weather Forecasts (ECMWF) reanalysis data and a scatterometer-derived
wind product. Seasonal and interannual variations of the anticyclonic eddy in the Kuril Basin are also revealed using T/P
SLA. 相似文献
115.
2003年西北太平洋热带气旋活动特征分析 总被引:1,自引:0,他引:1
本文综述了2003年西北太平洋上热带气旋活动特征,并对西北太平洋副热带高压特征量及赤道东太平洋海温与常年进行比较和相关分析,从而找出2003年西北太平洋热带气旋活动特征的成因。 相似文献
116.
117.
Graham P. Wilson Angela L. Lamb Melanie J. Leng Silvia Gonzalez David Huddart 《Estuarine, Coastal and Shelf Science》2005,64(4):685-698
Microfossil analysis (e.g. diatoms, foraminifera and pollen) represents the cornerstone of Holocene relative sea-level (RSL) reconstruction because their distribution in the contemporary inter-tidal zone is principally controlled by ground elevation within the tidal frame. A combination of poor microfossil preservation and a limited range in the sediment record may severely restrict the accuracy of resulting RSL reconstructions. Organic δ13C and C/N analysis of inter-tidal sediments have shown some potential as coastal palaeoenvironmental proxies. Here we assess their viability for reconstructing RSL change by examining patterns of organic δ13C and C/N values in a modern estuarine environment. δ13C and C/N analysis of bulk organic inter-tidal sediments and vegetation, as well as suspended and bedload organic sediments of the Mersey Estuary, U.K., demonstrate that the two main sources of organic carbon to surface saltmarsh sediments (terrestrial vegetation and tidal-derived particulate organic matter) have distinctive δ13C and C/N signatures. The resulting relationship between ground elevation within the tidal frame and surface sediment δ13C and C/N is unaffected by decompositional changes. The potential of this technique for RSL reconstruction is demonstrated by the analysis of part of an early Holocene sediment core from the Mersey Estuary. Organic δ13C and C/N analysis is less time consuming than microfossil analysis and is likely to provide continuous records of RSL change. 相似文献
118.
渤海裸甲藻和链状亚历山大藻的麻痹性贝毒毒素分析 总被引:1,自引:0,他引:1
目的:分析渤海裸甲藻(Gymnodinium sp.)和链状亚历山大藻(Alexandrium catenella)的麻痹性贝毒毒素,为渤海天津海域的赤潮研究积累基础数据。方法:通过实验室培养裸甲藻和链状亚历山大藻,选取对数生长期、平台生长期的裸甲藻以及平台生长期的链状亚历山大藻,利用高效液相色谱法(HPLC)对这两种微藻进行麻痹性贝毒(PSP)毒素分析。结果:裸甲藻细胞内不含有麻痹性贝毒(PSP);链状亚历山大藻细胞内含有C毒素和GTX1-4毒素,该微藻每个细胞毒素含量约为10.81 fmol/cell。结论:裸甲藻细胞内虽不含有麻痹性贝毒(PSP),但不能排除其含有其它毒素的可能。链状亚历山大藻细胞内含有麻痹性贝毒(PSP),属于有毒微藻,需要对其进行密切监测。 相似文献
119.
南海北缘东部盆地油气资源研究 总被引:5,自引:0,他引:5
南海北缘东部的珠江口盆地及台西南盆地蕴藏着十分丰富的油气资源,根据区域构造背景、盆地发育分布的特点及中、新生代的油气地质条件,结合含油气构造、油气田、油气井的分布规律,利用油气资源评价的理论、方法,对区内的油气资源进行了综合研究,并按照油气资源状况划分出油气富集区、油气潜力区、油气远景区,在此基础上,再进一步划分出4条油气富集带、11条油气潜力带、8条油气远景带,充分显示了该区石油、天然气的分布规律和油气地质特点,为商业性的勘探开发和理论研究奠定了基础。 相似文献
120.