碩士 / 國立中央大學 / 應用地質研究所 / 100 / Oil will polluted the coastal area by ocean current,wind, tide or other factors after oil spills from ocean. Moreover, the oil on the coastal area will affected ecosystem environment and people amusement life. The concentration of the BTEX is the index to identify the degree of oil pollution. Benzene, as one of the BTEX compounds, is recognized to be carcinogenicity and high toxicity. It may threat coastwise ecosystem and human health. Therefore, the understanding of benzene transport behavior in costal aquifers is important for predictions of contaminated zones, organization of emergency treatment and designs of remediation plans. This study employs the HYDROGEOCHEM numerical model to simulate two-dimensional benzene pollutants transport procedures in estuary aquifers. A profile estuary aquifer with 1100m in length and 100m in depth in Baldwin County, Alabama, which been polluted in 2010 oil spill event, is considered as study area in the illustrated examples. The objection of this study is to quantify the influence of benzene transport under hydrogeological conditions of tidal fluctuations and beach slopes. With the change of model mesh and modification of boundary condition in HYDROGEOCHEM, the model rational response benzene pollution under tidal fluctuations and beach slopes. Simulation results show that tidal fluctuations will lead to upper saline plume (USP) near the ground surface of the beach slope. Such local circulation flows will trap benzene plume to move toward the land. However, the plume may migrate to deeper aquifers. The sizes and location of benzene plume are highly relevant to the local circulation flows, and the behavior of local circulation flows depends on the effects of tidal amplitudes and surface slopes along coastal lines. Base on the field-scale conditions, results show that a doubled tidal amplitude increasing will lead to the increased plume size with 40m in length and 20m in depth. Additionally, a tripled beach slopes will lead to 50m plume movement toward the land. Simulation results also show that steep beach slopes will enhance self purification (clean) of benzene plumes. The most severe condition is that the large tidal amplitude and small slopes will cause a long self purification (clean) time for benzene plume. This study then employed the simulation results to apply to field-scale coast topographic conditions. The results show that the distance of saltwater wedges and the depth of benzene plumes exists a positive correlation between shapes of coastal lines.
| Identifer | oai:union.ndltd.org:TW/100NCU05503041 |
| Date | January 2012 |
| Creators | Yi-Ming Wei, 魏意銘 |
| Contributors | Chuen-Fa Ni, 倪春發 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 95 |
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