| Optical characteristics and solar photodegradation of dissolved organic matter in Arkansas River, USA |
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| 作者姓名： | Faye ZHAO Xiaodong MA |
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| 作者单位： | [1]Yale University, New Haven, CT06511, USA [2]Graduate Institute of Technology, University of Arkansas at Little Rock, 2801 S. Univ. Ave., Little Rock, AR 72204, USA |
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| 摘 要： | Dissolved organic matter （DOM）, a mixture of numerous organic compounds of 30 to 300000 D, exists in all natural water resources including rivers, lakes and oceans, and plays a very important role in global carbon cycle and ecology. The DOM molecules absorb UV light strongly in short wavelengths and prevent microorganisms from being damaged by solar UV irradiation. Meanwhile, the large DOM molecules are then photodegraded into inorganic carbon and smaller organic molecules which are easier for bacterioplankton to digest. The Arkansas River is one of the largest rivers in the US, and a major input of organic materials to the Mississippi River and Gulf of Mexico. However, the photochemical properties of the DOM in the river water have not been investigated. To study this photodegradation process of the Arkansas River, water samples from the river were collected, filtered, sealed into quartz flasks, and exposed to sunlight for up to 15 hours. Some samples were retrieved from the flasks at certain time intervals. The intensity of the sunlight was measured during the exposure process at 30 min to 1 hr intervals. UV-vis absorption, fluorescence emission, 3D fluorescence spectra and DOM concentrations were determined for all retrieved samples. It was found that the total DOM concentration decreased while the dissolved inorganic carbon （DIC） concentration increased in the samples. UV absorption and fluorescence intensity of DOM decreased exponentially. The disappearance rate of UV absorption varied with wavelength. The loss of integral fluorescence was about 2.6 times that of the UV absorption at the excitation wavelength. In addition, the quantum yields also decreased, and the peak position of 3D fluorescence scan shifted to shorter wavelength.
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| 关 键 词： | 河流 太阳辐射 溶解有机物 水文化学 |
Optical characteristics and solar photodegradation of dissolved organic matter in Arkansas River, USA |
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| Faye ZHAO Xiaodong MA.Optical characteristics and solar photodegradation of dissolved organic matter in Arkansas River, USA[J].Chinese Journal of Geochemistry,2006,25(B08):279-279. |
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| Abstract: | |
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| Keywords: | Arkansas River photodegradation solar irradiation dissolved organic matter UV-vis and fluorescence spectroscopy |
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