| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋環境資訊學系 === 99 === Abstract
The purpose of this study is to understand the variation of seawater transparency at Bisha Fishing Harbor in Keelung, Taiwan by using Secchi disk, and then analyze the possible factors that may influence its variation. After measuring every week for a year, the result shows that the average seawater transparency at Bisha Fishing Harbor is low to 4.8 ±1.3 meters in summer, and it’s because that plankton would perform photosynthesis under the sunshine; in contrast, the transparency in winter is high to 7.6 ±2.0 meters. From the continuous measurements for 30 days, the result shows that there is a variation period of 4~5 days by using Fast Fourier Transformation. According to the analysis of correlation, it indicates that the transparency is somehow related to the wind speed variation, but not correlated with tides. We can find that during typhoon and strong northeast monsoon periods, the transparency reduces dramatically because of the sediments disturbed by stormy waves. During the measuring period, we also found a lot of artificial interference, for example, the floating garbage and greasiness on the sea, human activities around the port, construction progressed in embankments and so on. These factors may influence the seawater transparency indirectly, and lower the visibility of the sea.
Keywords: Secchi disk, Transparency, Bisha Fishing Harbor
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