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- Tesi, Tommaso, et al.
(author)
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Source, diagenesis, and fluxes of particulate organic carbon along the western Adriatic Sea (Mediterranean Sea)
- 2013
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In: Marine Geology. - : Elsevier BV. - 0025-3227 .- 1872-6151. ; 337, s. 156-170
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Journal article (peer-reviewed)abstract
- In this study, we investigated the modern organic carbon (OC) cycling along the clinoform-shaped deposit that developed after the attainment of the modern sea-level in the Adriatic Sea (similar to 5.5 kyr cal BP). Newly acquired data were combined with published results to characterize the (i) origin, (ii) diagenesis, and (iii) fluxes of OC along the Adriatic clinoform. delta C-13, Delta C-14, and lignin phenols were used to constrain the composition of CC accumulating in surface sediments. Sediment cores collected at different water depths were used to describe the early diagenesis during burial in different regions. In addition, on the basis of an extensive number of accumulation rates and CC data, we assessed the flux of CC to the seabed and its burial. Our results showed that terrigenous CC is the dominant CC source in the Po prodelta mainly in the form of pre-aged soil-derived CC and vascular plant fragments. Along the clinoform, both Delta 14C and the concentration of lignin-derived phenols decreased with increasing distance from the Po prodelta indicating the influence of an additional pool of aged CC that gradually becomes more important because of its selective preservation during the sediment transport. As a result, degradation rates (k) decreased along the clinoform as a function of the sediment oxidative history. The calculated half-life of reactive OC (t(1/2)) was similar to 14.6 yrs in the Po prodelta whereas topset/forest deposits south of this region exhibited higher values, similar to 100 yrs, indicating the presence of refractory material. In the distal bottomset region, the tip was particularly high ranging from similar to 255 to similar to 912 yrs. Because of the significant southward component of the sediment transport, the CC deposition in the southern surface sediments exceeded the local CC input via rivers (ratio deposition/input 12). Conversely, the northern Adriatic was characterized by a marked imbalance (ratio deposition/input 0.3-0.5). According to our calculations, the CC flux to the seabed along the clinoform was similar to 309 Gg of C per year whereas the OC burial was similar to 180 Gg of C per year, corresponding to an overall burial efficiency of similar to 59%.
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