Journal
ENVIRONMENTAL POLLUTION
Volume 239, Issue -, Pages 205-214Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2018.03.108
Keywords
Dissolved organic matter; Cu(II); Metal-DOM binding; Allochthonous/autochthonous DOM; Photochemical degradation; Microbial degradation
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Funding
- National Natural Science Foundation of China [51479187, 51522902]
- Wisconsin Sea Grant [R/HCE-16]
- NSF-MRI [1233192]
- Youth Innovation Promotion Association CAS [2016286]
- Division Of Ocean Sciences
- Directorate For Geosciences [1233192] Funding Source: National Science Foundation
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Effects of photochemical and microbial degradation on variations in composition and molecular-size of dissolved organic matter (DOM) from different sources (algal and soil) and the subsequent influence on Cu(II) binding were investigated using UV-Vis, fluorescence excitation-emission matrices coupled with parallel factor analysis, flow field-flow fractionation (FIFFF), and metal titration. The degradation processes resulted in an initial rapid decline in the bulk dissolved organic carbon and chromophoric and fluorescent DOM components, followed by a small or little decrease. Specifically, photochemical reaction decreased the aromaticity, humification and apparent molecular weights of all DOM samples, whereas a reverse trend was observed during microbial degradation. The FIFFF fractograms revealed that coagulation of both protein-and humic-like DOM induced an increase in molecular weights for algal-DOM, while the molecular weight enhancement for allochthonous soil samples was mainly attributed to the self-assembly of humic-like components. The Cu(II) binding capacity of algal-derived humic-like and fulvic-like DOM consistently increased during photo-and bio-degradation, while the soil-derived DOM exhibited a slight decline in Cu(II) binding capacity during photo-degradation but a substantial increase during microbial degradation, indicating source-and degradation-dependent metal binding heterogeneities. Pearson correlation analysis demonstrated that the Cu(II) binding potential was mostly related with aromaticity and molecular size for allochthonous soil-derived DOM, but was regulated by both DOM properties and specific degradation processes for autochthonous algal-derived DOM. This study high-lighted the coupling role of inherent DOM properties and external environmental processes in regulating metal binding, and provided new insights into metal-DOM interactions and the behavior and fate of DOM-bound metals in aquatic environments. (C) 2018 Elsevier Ltd. All rights reserved.
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