کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6364334 | 1623068 | 2016 | 10 صفحه PDF | دانلود رایگان |
- SOM's chemical diversity was revealed by its abundant non-redundant formulas.
- Anthropogenic activities affect SOM's complexity and diversity.
- HUSO of SOM was highly associated with apparent humic-like indicators.
- The ratios of aromatics/alipatics discriminate SOMs' diagenesis and the sources.
Few studies have been conducted to examine the spatial heterogeneity of riverine sediment organic matter (SOM) at the molecular level. The present study explored the chemical and molecular heterogeneity of alkaline-extractable SOM from riverine sediments via multiple analytical tools including molecular composition, absorption and fluorescence spectra, and molecular size distributions. The riverine SOM revealed complex and diverse characteristics, exhibiting a great number of non-redundant formulas and high spatial variations. The molecular diversity was more pronounced for the sediments affected by a higher degree of anthropogenic activities. Unlike the cases of aquatic dissolved organic matter, highly-unsaturated structures with oxygen (HUSO) of SOM were more associated with the spectral and size features of humic-like (or terrestrial) substances than aromatic molecules were, cautioning the interpretation of the SOM molecules responsible for apparent indicators. Noting that a higher detection rate (DR) produces fewer common molecules, the common molecules of 23 different SOMs were determined at a reasonable DR value of 0.35, which accounted for a small portion (5.8%) of all detected molecules. They were mainly CHO compounds (>98%), which positively correlated with spectral indicators of biological production. Despite the low abundance, however, the ratios of aromatic to aliphatic substances could be indexed to classify the common molecules into several geochemical molecular groups with different degrees of the associations with the apparent spectral and size indicators.
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Journal: Water Research - Volume 100, 1 September 2016, Pages 222-231