Fulvic acid in microlayer waters of the Gerlache Inlet Sea (Antarctica): Their distribution in dissolved and particulate phases

In this work we studied the distribution of humic compounds between microlayer and subsurface waters. Both dissolved (DFA) and particulate (PFA) matter were considered. Humic acids were not found. The amount of total particulate matter is the same both in microlayer and subsurface waters. Conversely, particulate organic matter and fulvic acid concentrations were greater in microlayer waters. Enrichment factors (microlayer PFA/subsurface PFA and microlayer DFA/subsurface DFA) show a greater presence of fulvic acids in the microlayer. Moreover, the enrichment process is greater for the particulate phase. C/N values both in microlayer and subsurface waters are greater for DFA with respect to PFA and C/N values for DFA of microlayer are greater than that of subsurface waters. So DFA could be older than PFA, and DFA of subsurface waters younger than that of microlayer waters. For PFA S/C ratios in microlayer waters are greater than that of subsurface waters, underlining that the enrichment process is selective as regards sulphur-containing structures.