碩士 / 國立成功大學 / 地球科學系專班 / 96 / Owing to its hot/humid weathers and strong tectonic activities, Taiwan is considered as a region that has the highest chemical weathering in the world. This study is focused on discussion of the variations of chemical compositions in the Zengwen estuary. These concentration variations of major and trace elements are strongly influenced by, seasonal variability of precipitation,in particular during typhoon. Episode.From June 2006 to June of 2007, 60 river waters at Sailee Bridage and 12 at Konghok Bridage along the Zengwen River ,as well as 2 rains, in wet and dry seasons were analyzed for major（i.e.Na、K、Mg、Ca、Cl、S、Si）and trace elements（i.e.Rb、Ba、Al、Cr、As、Br、Sr、Zn）by SF-ICP-MS.
These results show high Mg, Ca, K, SO42- during lower runoff periods,because of purging effect of river water onto the bedrocks and caused major ions dissolution. When the water flow is greater than 38m3/s, these elements were diluted. The average ratios of Mg/Cl, Ca/Cl and Na/Cl is 1.166, 2.20 and 2.252, respectively in rainy seasonThese ratios are high than seawater values, probably reflecting weathering of chlorite, Mg mineral, carbonate and Na feldspar. The average ratios of Mg/Cl, Ca/Cl and Na/Cl is 0.095, 0.024 and 0.885, respectively in dry season, similar to IAPSO values of Mg/Cl = 0.1,Ca/Cl = 0.019 and Na/Cl = 0.86. These chemical ratios indicate clear seawater influence. The Ca/Cl ratio increases about 90 times from dry to wet season, whereas Na/Cl increased only 2.5 times. In addition, the slope in the (Ca/Cl)n vs. (Na/Cl) n plot is 1.3 in wet season,reflecting preferential weathering of Ca-bearing minerals.Na and Br in the river water at Konghok Bridage is13.47 and 66.87 times respectively higher than the Sailee Bridage in wet season; whereas the differences between the two stations reduced to 1.47 and 2.46 times, respectively. It appears Zengwen River waters tend to be more fresh water in wet season. This agrees also with Ca and Mg concentrations.The Multivariate Principle Component and Factor Analysis Method were applied to evaluate main controlling factors of the river water chemical compositions. The most important factors are rock weathering, sea water, the Zengwen reservoir discharge, runoff and precipitation.
| Identifer | oai:union.ndltd.org:TW/096NCKU5135011 |
| Date | January 2008 |
| Creators | Hui-chen Hsu, 許慧真 |
| Contributors | Chen-Feng You, 游鎮烽 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 100 |
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