期刊
CHEMOSPHERE
卷 194, 期 -, 页码 405-413出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2017.11.172
关键词
Dissolved organic matter; Dissolved black carbon; Photochemistry; Apparent singlet oxygen quantum yield; Spectroscopic indices; Predictive models
资金
- National Key Basic Research Program of China [2014CB441103]
- National Natural Science Foundation of China [21407073, 21622703, 21507056]
- Philosophy and Social Science Foundation of Higher Education Institutions of Jiangsu Province [2017SJB0234]
- Natural Science Foundation of Higher Education Institutions of Jiangsu Province [17KJB120004]
- National Natural Science Foundation of Jiangsu [BK20150568]
Dissolved black carbon (DBC) is ubiquitous in aquatic systems, being an important subgroup of the dissolved organic matter (DOM) pool. Nevertheless, its aquatic photoactivity remains largely unknown. In this study, a range of spectroscopic indices of DBC and humic substance (HS) samples were determined using UV-Vis spectroscopy, fluorescence spectroscopy, and proton nuclear magnetic resonance. DBC can be readily differentiated from HS using spectroscopic indices. It has lower average molecular weight, but higher aromaticity and lignin content. The apparent singlet oxygen quantum yield (Phi(singlet) (oxygen)) of DBC under simulated sunlight varies from 3.46% to 6.13%, significantly higher than HS, 1.26% 3.57%, suggesting that DBC is the more photoactive component in the DOM pool. Despite drastically different formation processes and structural properties, the Phi(singlet oxygen) of DBC and HS can be well predicted by the same simple linear regression models using optical indices including spectral slope coefficient (S275-295) and absorbance ratio (E-2/E-3) which are proxies for the abundance of singlet oxygen sensitizers and for the significance of intramolecular charge transfer interactions. The regression models can be potentially used to assess the photoactivity of DOM at large scales with in situ water spectra photometry or satellite remote sensing. (C) 2017 Elsevier Ltd. All rights reserved.
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