Discerning natural and anthropogenic organic matter inputs to salt marsh sediments of Ria Formosa lagoon (South Portugal)

24 páginas.- 8 figuras.- 4 tablas.- 122 referencias.- Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-09235-9) contains supplementary material, which is available to authorized users.

Sedimentary organic matter (OM) origin and molecular composition provide useful information to understand carbon cycling in coastal wetlands. Core sediments from threors’ Contributionse transects along Ria Formosa lagoon intertidal zone were analysed using analytical pyrolysis (Py-GC/MS) to determine composition, distribution and origin of sedimentary OM. The distribution of alkyl compounds (alkanes, alkanoic acids and alkan-2-ones), polycyclic aromatic hydrocarbons (PAHs), lignin-derived methoxyphenols, linear alkylbenzenes (LABs), steranes and hopanes indicated OM inputs to the intertidal environment from natural—autochthonous and allochthonous—as well as anthropogenic. Several n-alkane geochemical indices used to assess the distribution of main OM sources (terrestrial and marine) in the sediments indicate that algal and aquatic macrophyte derived OM inputs dominated over terrigenous plant sources. The lignin-derived methoxyphenol assemblage, dominated by vinylguaiacol and vinylsyringol derivatives in all sediments, points to large OM contribution from higher plants. The spatial distributions of PAHs (polyaromatic hydrocarbons) showed that most pollution sources were mixed sources including both pyrogenic and petrogenic. Low carbon preference indexes (CPI > 1) for n-alkanes, the presence of UCM (unresolved complex mixture) and the distribution of hopanes (C29–C36) and steranes (C27–C29) suggested localized petroleum-derived hydrocarbon inputs to the core sediments. Series of LABs were found in most sediment samples also pointing to domestic sewage anthropogenic contributions to the sediment OM. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

The authors received funding from EU Erasmus Mundus Joint Doctorate fellowship (FUECA, University of Cadiz, Spain) for Mukesh Kumar. The research was supported by EU contract numbers FP7-ENV-2011, Grant agreement no: 282845 and FP7- 534 ENV-2012 Grant agreement no: 308392 and also from MINECO project INTERCARBON (CGL2016-78937-R).

Peer reviewed