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Lee Seokjae Yang Subin Lee Dongjoon Choi Hangseok Won Jongmuk 《Hydrogeology Journal》2023,31(5):1245-1257
Understanding contaminant transport in clay-containing soils is critical for accurate prediction of the travel distances of contaminants and for the design and implementation of corresponding remediation plans. This study examined the breakthrough behavior of methylene blue (MB) through sand-illite mixtures using laboratory soil-column experiments at five inlet concentrations, three flow rates, and five illite contents. Kinetic and equilibrium adsorption tests were performed to evaluate the maximum adsorption capacities of the sand and illite used in the soil-column experiments. In addition, the bed efficiency, MB saturation, and adsorption rate were calculated to quantitatively describe the observed breakthrough curves. The observed breakthrough curves, bed efficiencies, MB saturations, and adsorption rates in this study demonstrated the presence of a threshold illite content of ~10% for the adsorption efficiency of contaminants. This implies the need to evaluate the threshold clay content for accurate predictions of contaminant transport through gap-graded clay-containing soils.
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随着勘探区域逐渐从陆地过渡到海洋,勘探目标逐渐趋于复杂化,高精度成像方法已经成为海洋油气勘探的瓶颈技术。高斯束偏移是一种灵活且高效的深度域偏移方法,对实际资料成像具有较好的适应性。该文发展了一种适应于海洋观测系统的高精度高斯束偏移方法,首先将海上接收的共偏移距地震记录进行加窗局部倾斜叠加,通过数学变换将共炮域公式推广到共偏移距域,再从炮点和检波点分别进行射线追踪,最后采用数据驱动的方式进行成像。一方面,考虑到地下介质的各向异性,引入了各向异性射线追踪方程;另一方面,根据有效信号和干扰信号在τ-p域中的相干性差异,在高斯束偏移过程中对地震信号进行控制,降低偏移剖面中的随机噪声,提高同相轴的连续性,最终实现了一种VTI介质共偏移距域数据驱动控制束偏移理论方法。在实现算法的基础上,通过各向异性洼陷模型、修改的SEG/Hess VTI模型及海上实际资料成像试处理,结果表明:各向异性参数对共偏移距道集中的大偏移距信息成像质量改善明显;当地层各向异性不能忽略时,新方法能够更加准确地恢复地下的复杂构造;新方法能够在一定程度上提高低信噪比数据的偏移成像效果。 相似文献
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新元古代—早古生代华南裂谷系的格局及其演化 总被引：13，自引：0，他引：13
本文运用地层、构造与地质事件的综合研究方法,对新元古代—早古生代华南裂谷系的格局及其演化进行了研究。该裂谷系发生于晋宁期造山(约820Ma)后不久的青白口纪晚期(约815Ma),有皖浙赣堑垒带、湘桂台阶式斜坡带和南华裂谷海盆3个部分。皖浙赣堑垒带由"两谷两隆"组成,火山活动强烈,消亡于"青白口纪"末(约780Ma)。湘桂斜坡带拥有武陵(红板溪)、雪峰(灰板溪)和钦杭西段(黑板溪)3个台阶式斜坡。南华裂谷海盆以南岭中央海盆为核心,外侧有武夷、岭南两个水下裂陷块体和闽中裂谷等。海盆于志留纪时由东向西逐渐闭合造山,以"北贴西拼"为主要运动方式,形成了复杂的复合构造格局。由于南岭与岭南块体不同步的向西推移并南北贴合形成了河池-定南挤压转换式拼接带,出现了南岭东西向构造带的雏形。钦杭裂谷是华南裂谷系的主干和主要海水通道,其南端的钦州残留裂谷海槽于中二叠世末才宣告封闭。华南裂谷系的形成发展是华南地史上的一个重大事件,对后期地质构造以及岩浆成矿活动都具有重要的约束作用。 相似文献
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E. A. G. Schuur B. W. Abbott W. B. Bowden V. Brovkin P. Camill J. G. Canadell J. P. Chanton F. S. Chapin III T. R. Christensen P. Ciais B. T. Crosby C. I. Czimczik G. Grosse J. Harden D. J. Hayes G. Hugelius J. D. Jastrow J. B. Jones T. Kleinen C. D. Koven G. Krinner P. Kuhry D. M. Lawrence A. D. McGuire S. M. Natali J. A. O’Donnell C. L. Ping W. J. Riley A. Rinke V. E. Romanovsky A. B. K. Sannel C. Schädel K. Schaefer J. Sky Z. M. Subin C. Tarnocai M. R. Turetsky M. P. Waldrop K. M. Walter Anthony K. P. Wickland C. J. Wilson S. A. Zimov 《Climatic change》2013,119(2):359-374
Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing. 相似文献
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T. M. Midhuna Biswadip Gharai Subin Jose P. V. N Rao 《Journal of the Indian Society of Remote Sensing》2017,45(4):685-697
Satellite-based measurements of aerosols are one of the most effective ways to understand the role of aerosols in climate in terms of spatial and temporal variability. In the present study, we attempted to analyse spatial and temporal variations of satellite derived aerosol optical depth (AOD) over Indian region using moderate resolution imaging spectrometer over a period of 2001–2011. Due to its vast spatial extent, Indian region and adjacent oceanic regions are divided into different zones for analysis. The land mass is sub divided into five different zones such as Indo Gangetic Plain (IGP), Indian mainland, North Eastern India (NE), South India-1 (SI-1), South India-2 (SI-2). Oceanic areas are divided into Arabian Sea and Bay of Bengal. Arabian Sea is further divided as three zones viz. Northern AS (NAS), Central AS (CAS) and Eastern AS (EAS) zones. Bay of Bengal is divided as North BoB (NBoB), West BoB (WBoB), Central BoB (CBoB), and East BoB (EBoB). The study revealed that among all the land regions, IGP showed the highest peak AOD value (0.52 ± 0.17) while SI-2 showed the lower values of AOD in all the months compared to all India average. The maximum AOD is observed during premonsoon season for all regions. During the winter, average AOD levels were substantially lower than the summer averages. Peak of aerosol loading (0.35 ± 0.159) is observed in March over NE region, whereas in all other regions, peak is observed during May. Frequency distribution of long term AOD (<0.2, 0.3–0.5, >0.5) shows a shift of frequency distribution of AOD from <0.3 to 0.3–0.5 during the study period in all regions except IGP. In IGP shift of frequency of AOD values occurs from 0.3–0.5 to >0.5. Oceanic areas also shows seasonal variation of AOD. Over Arabian Sea, high AOD values with greater variations were observed in summer monsoon season while in Bay of Bengal it is observed during winter monsoon. This is due to the high wind speed prevailing in Arabian Sea during monsoon season which results in production of more sea salt aerosol. Highest AOD values are observed over NAS during monsoon season and over NBOB during winter season. Lowest AOD values with its lower variations observed in both the central region of Arabian Sea and Bay of Bengal. 相似文献
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