Structural and functional chemical properties of marine and coastal sedimentary humic acids: Fid-Bau Portal

Structural and functional chemical properties of marine and coastal sedimentary humic acids

Senesi, N. / Sakellariadou, F.

AbstractHumic acids isoisolated from surface marine and coastal sediments of the North Aegean Sea are characterized by a predominant aliphatic nature associated with nitrogenous functional groups, low levels of organic free radical content, and the presence of fluorophores emitting principally at low wavelength. This suggests a prevalent autochthonous origin (algal sources). Humic acids from subsurface marine sediments are less aliphatic, low in nitrogen content, and rich in free radicals and highly conjugated fluorophores. This suggests the occurrence of extended aging transformations. The presence of lignin-derived components in the coastal river sediment humic acid indicat a high contribution from terrestrial sources for this sample. A combination of organic free radical concentration, C/N ratio, H%, and C/H ratio may be a simple and reliable source indicator for distingusihing marine-derived (algal sources) from terrestrially-derived (vascular plant sources) humic acids. The high ash content and the prevalence of carboxylate over carboxylic groups suggest extended associations of inorganic materials with sedimentary humic acids.