鈾系和釷系同位素比值的不平衡現象已成功的成為研究地表的風化過程和風化速率變化的指標，然而在台灣，利用量測鈾系和釷系放射性同位素活度的不平衡對於颱風引起的風化及侵蝕機制，此方法卻從未曾受到重視。為此，本研究即提出利用γ-能譜儀建立一系列颱風引起懸浮沈積物的放射性同位素活度，藉由210Pb/226Ra 和 228Th/228Ra的不平衡間比值的不平衡關係，來探討濁水溪流域的風化過程。

本研究分為兩部分，在第一部份中提出了利用γ-能譜儀進行放射性活度測量的優勢及所受限之處，並建立一套測量樣品的標準流程。其中，經由γ射線能量校正，樣品幾何校正及γ-射線自吸收的校正之後的量測結果，非常符合利用α-能譜儀的方法的測量值，並且也相符於比對實驗中其他同樣利用γ-能譜儀方法7個實驗室量測結果，更加證實了本研究利用γ-能譜儀進行放射性活度測量的精確度及可信賴性。

在第二部分中則提出了利用γ-能譜儀對颱風引起的濁水溪懸浮沈積物的量測結果，其中，用來探討化學風化的 228Th/228Ra皆相當接近於1，表示濁水溪流域的化學風化相當弱，台灣地區典型的快速物理風化才是主控此流域的主要因素。然而在敏督利颱風強烈侵蝕下所帶來的濁水溪下游懸浮沈積物中，210Pb/226Ra的比值明顯大於1，其原因是受到大量注入附近農耕地有機顆粒所造成的稀釋效應之故，相較於艾利颱風僅注入少量的有機顆粒， 210Pb/226Ra的比值亦相對的達到平衡。

Uranium and Thorium- series disequilibria have been used successfully in the study of weathering processes and rates. However, typhoons induced continental weathering and erosions translate process mechanism were never concerned by measuring the radioisotopes (radionuclides) activities disequilibrium in Taiwan. In this study, typhoons induced Choshui Riverine total suspended sediment (TSS) of 210Pb/226Ra and 228Th/228Ra disequilibrium were analysis to study the weathering processes by using gamma spectrometry in Choshui River.

In part 1, the advantage and limitation by using gamma spectrometry were proposed to determine the samples radioisotopes activities. The measurement through the standard sequence of processes and careful correction for (1) gamma-ray energy, (2) samples geometry and (3) gamma-ray self-absorption, are well agreed with other method such as alpha spectrometry. Results of comparison experience are also confirmed with performed by other 7 laboratories indicate the reliable and accuracy in this method.

In part 2, ratios of 228Th/228Ra results in typhoons induced Choshui Riverine TSS are all close to unity represent the typical rapidly physical weathering process with negligible chemical weathering dominated in Choshui River watershed. On the other hand, obviously 210Pb/226Ra disequilibria in downstream owing to numerous organic particles input from agriculture field by intense erosion in Typhoon Mindulle event. Nevertheless, insufficient amount of Typhoon Aere induced organic particles were inserted make the disequilibrium of 210Pb/226Ra ratios unclear occurred.

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