Abstract This study aims to understand the influence of weathering and human perturbation on spatial and temporal variability of major and trace element distributions in the Kaoping River basin. The collected data are used to elucidate the production, transport and export of major and trace elements from the Kaoping River basin. Experimental results show that the weathering index of the Kaoping River basin is rather high. The significant loss of major ions and enrichment of iron and aluminum from river suspended matter indicate the characteristic of high weathering rate in most tropical rivers. Particulate Si/Al mole ratios range from 1 to 2 showing that the distributions of dissolved and particulate matter are largely controlled by the weathering process of kaolinite and /or smectite formation. During the study period (2002), the physical and chemical weathering rates were estimated about 655.8 and 416.2 g/m2/yr, respectively. Both physical and chemical weathering rates are much lower than those estimated by Yang (2001) during the period of 1999-2000 [3601 g/m2/yr (physical weathering rate), 1146 g/m2/yr (chemical weathering rate)], due to significant difference in river discharge. However, the estimated physical and chemical weathering rates are still much higher than the world averages of physical (150 g/m2/yr) and chemical (33-40 g/m2/yr) weathering rates. The marked difference between this and Yang¡¦s estimates is caused from large difference in river discharge. Silicate weathering was estimated about 97.09 ¡Ó 2.41% of total chemical weathering in the Kaoping River basin. The temporal variations of enrichment factor (EF) for most particulate trace metals (Mn, Zn, Cu, Cr, Pb, Cd, and Hg) reveal a greater pollution status in the dry season than in the wet season. Spatial variations of EF also reveal a greater pollution in the downstream zone than in the upstream zone. Time-series observation showed that concentrations of particulate trace elements were inversely correlated with discharge. The significant correlation between the fluxes of dissolved and particulate trace elements and discharge suggesting that river discharge controlled largely the fluxes of major and trace elements. The annual variations of elemental fluxes were determined critically by the annual difference of river discharge. The distributions of particulate organic carbon (POC) and particulate nitrogen (PN) were similar between suspended matter in the Kaoping River and surface sediments in the Kaoping Canyon. The data of £_13Corg show that about 77.2% of organic matter derived from the Kaoping River basin deposit in the Kaoping Canyon. The Kaoping Canyon appears to play an important role on the transport and deposition of organic matter from the Kaoping River basin.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第21186号 / 人博第858号 / 新制||人||204(附属図書館) / 29||人博||858(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 小木曽 哲, 教授 石川 尚人, 教授 酒井 敏, 准教授 飯塚 毅 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DGAM