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991.
�봨8������ر����Ѵ��������乹������ 总被引:7,自引:2,他引:5
???ò??GPS????8????????????????????????????????????????????????????????:?????????-?????????γ?????200 km???????????????????????-????????????γ?????75 km?????????????????????????????????????????????????????????????????????????????????????????????? 相似文献
992.
十屋断陷是断坳叠置的复合盆地,充填了巨厚的断陷地层。其深部地层包括登娄库组、营城组、沙河子组以及火石岭组。在十屋断陷深部沉积了沙河子组-营城组和登娄库组两套烃源岩和良好的储盖层组合;由于断陷构造运动,形成大量的断裂构造和不整合面,构成了油气运移的有效通道,同时还形成有效断裂、断鼻构造圈闭以及不整合圈闭。综合分析认为,十屋断陷深部具有有利油气成藏生储盖组合。主要有下生上储式、自生自储式和上生下储式三种成藏模式。 相似文献
993.
与直井相比,水平井开发具有缩短油井井距,扩大泄油面积,提高临界锥流量,更好地控制注入流体、改善波及效率等优势。在相同采液量的情况下,水平井可以降低采液强度,减缓含水上升速度。特高含水期河流相储集层的顶部是剩余油富集区,利用水平井技术挖掘正韵律厚油层顶部剩余油,取得了很好的开发效果,最终采收率较直井开发提高了14个百分点。 相似文献
994.
盐城海岸带湿地景观格局变化研究 总被引:3,自引:0,他引:3
利用4个时相的陆地卫星遥感影像及相关资料,在遥感和地理信息系统技术支持下,对盐城国家级自然保护区的核心区和缓冲区进行了景观格局分析。结果表明,从1988~2002年,淤泥质滩涂面积增长了13.33%;分形维数从1.0991上升到1.1166,蔓延度指数从76.4426下降到53.1142,表明研究区形状趋于规则,人为干扰程度增大,景观有破碎有上升的趋势,该边缘生境异质性在逐步增强;人类对滩涂的影响增加,逐渐成为影响该生态系统的主要力量。 相似文献
995.
Onshore sandbar migration at Tairua Beach (New Zealand): Numerical simulations and field measurements 总被引:1,自引:0,他引:1
B. van Maanen P.J. de Ruiter Giovanni Coco K.R. Bryan B.G. Ruessink 《Marine Geology》2008,253(3-4):99-106
We observed the onshore migration (3.5 m/day) of a nearshore sandbar at Tairua Beach, New Zealand during 4 days of low-energy wave conditions. The morphological observations, together with concurrent measurements of waves and suspended sediment concentrations, were used to test a coupled, wave-averaged, cross-shore model. Because of the coarse bed material and the relatively low-energy conditions, the contribution of the suspended transport to the total transport was predicted and observed to be negligible. The model predicted the bar to move onshore because of the feedback between near-bed wave skewness, bedload, and the sandbar under weakly to non-breaking conditions at high tide. The predicted bathymetric evolution contrasts, however, with the observations that the bar migrated onshore predominantly at low tide. Also, the model flattened the bar, while in the observations the sandbar retained its steep landward-facing flank. A comparison between available observations and numerical simulations suggests that onshore propagating surf zone bores in very shallow water (< 0.25 m) may have been responsible for most of the observed bar behaviour. These processes are missing from the applied model and, given that the observed conditions can be considered typical of very shallow sandbars, highlight a priority for further field study and model development. The possibility that the excess water transported by the bores across the bar was channelled alongshore to near-by rip-channels further implies that traditional cross-shore measures to judge the applicability of a cross-shore morphodynamic model may be misleading. 相似文献
996.
��Ӷ��Ѵ������ֽ�������ЧӦ 总被引:1,自引:1,他引:0
????????????????????????β??????????????1985??2006??β?????仯??????????1???????????????????????????????????????????????????????????????????????????2????????????????????????????????1?λ??????????£??????????ε?????????????????????1?γ????????仯?????3?? ????????????????仯?????????????????仯???????????????????????????? 相似文献
997.
998.
999.
为了解红树林不同潮位沉积物中底栖真核生物群落分布,基于18S rRNA基因采用高通量测序方法分析了广西北仑河口陆缘、林中和海缘3个潮位红树林沉积物中底栖生物群落结构。结果表明,北仑河口潮间带红树林沉积物中底栖生物多样性丰富,Shannon-Wiener指数变化范围在6. 08~6. 73之间; PCA分析表明潮间带中底栖生物群落差异较大,陆缘红树林中扁形动物、节肢动物和软体动物相对丰度较高,林中区域中纤毛虫、环节动物和轮虫相对丰度较高,海缘红树林中硅藻相对丰度较高;红树林中主要OTUs有桡足类的太平洋纺锤水蚤(Acartia pacifica)、硅藻类的海链藻(Thalassiosira sp.)、纤毛虫类的前管虫(Prorodon teres)、多毛类的小头虫(Capitella sp.)。高通量测序方法能较全面反映红树林区微型/小型底栖生物群落,研究结果为丰富红树林底栖生物群落研究和解析底栖生物在红树林生态系统发挥的作用提供基础数据。 相似文献
1000.
P.P. Povinec J. de Oliveira E.S. Braga J.-F. Comanducci J. Gastaud M. Groening I. Levy-Palomo U. Morgenstern Z. Top 《Estuarine, Coastal and Shelf Science》2008
Stable isotopes, tritium, radium isotopes, radon, trace elements and nutrients data were collected during two sampling campaigns in the Ubatuba coastal area (south-eastern Brazil) with the aim of investigating submarine groundwater discharge (SGD) in the region. The isotopic composition (δD, δ18O, 3H) of submarine waters was characterised by significant variability and heavy isotope enrichment. The stable isotopes and tritium data showed good separation of groundwater and seawater groups. The contribution of groundwater in submarine waters varied from a few % to 17%. Spatial distribution of 222Rn activity concentration in surface seawater revealed changes between 50 and 200 Bq m−3 which were in opposite relationship with observed salinities. Time series measurements of 222Rn activity concentration in Flamengo Bay (from 1 to 5 kBq m−3), obtained by in situ underwater gamma-spectrometry showed a negative correlation between the 222Rn activity concentration and tide/salinity. This may be caused by sea level changes as tide effects induce variations of hydraulic gradients, which increase 222Rn concentration during lower sea level, and opposite, during high tides where the 222Rn activity concentration is smaller. The estimated SGD fluxes varied during 22–26 November between 8 and 40 cm d−1, with an average value of 21 cm d−1 (the unit is cm3/cm2 per day). The radium isotopes and nutrient data showed scattered distributions with offshore distance and salinity, which implies that in a complex coast with many small bays and islands, the area has been influenced by local currents and groundwater–seawater mixing. SGD in the Ubatuba area is fed by coastal contaminated groundwater and re-circulated seawater (with small admixtures of groundwater), which claims for potential environmental concern with implications on the management of freshwater resources in the region. 相似文献