photochemical reactions of soluble humic substances in seawater

• Main Author: 劉嘉元
• Other Authors: Wei-hsien Wang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/94850452754995828615

碩士 === 國立中山大學 === 海洋資源學系 === 88 === Abstract Humic substances are important photosensitizer for the photochemical reaction in waters. In this study, the photochemical reactions sensitized by humic substances isolated from natural waters were studied. Aldrich humic acid (AHA) and fulvic acids extracted from Kaoping (GFA) and Shitzyywan (SFA) were used for comparison. Humic substances were fractionated by CFF equipped with 10 kD and 1 kD filters. Photosensitized [1O2]SS was measured for different types of humic substances, and different molecular weight fractions of humic substances by using furfurly alcohol as trapping agent and light sources were sun and Hg lamp. The effect of the wavelength of light sources on [1O2] SS was also studied. It is concluded that SHA has better absorption at both ultraviolet and visible regions so that SHA generates more singlet oxygen than GFA and SFA. The HMW fraction ( MW > 10 kD ) has better absorption at ultraviolet region (λ< 400 nm ), however, the LMW fraction absorbs more visible light ( 400 nm <λ< 800 nm ). For all humic substances, HMW fraction generates more singlet oxygen than MMW and LMW fractions. Photochemical reactions sensitized by humic substances were more efficient by irradiating with ultraviolet than with visible light.