engleski

Mechanisms of Land-Sea Interactions - The Distribution of Metals and Sedimentary Organic Matter in Sediments of a River-Dominated Mediterranean Karstic Estuary

A small, microtidal, and river-dominated estuary was investigated, as a model for the land-sea interactions of a typical karstic Mediterranean environment, on the distribution of metals (Cu, Pb, Zn, Cd) and the characteristics, distribution, and origin of sedimentary organic matter (SOM). The longitudinal distribution of heavy metals in sediments follows the sedimentation dynamics and deposition pattern of river-borne, clayey mineral particles. The highest concentration of metals was found in the restricted upper part of the estuary, characterized by rapid deposition of clayey particles and terrestrial sedimentary organic matter, and decreases toward the open sea. The vertical distribution of metals in sediment cores depends on the prevailing pH and Eh conditions. Significant increases of the concentrations of metals in the uppermost strata are the result of recent anthropogenic inputs. The share of the terrestrial component in sedimentary organic matter (SOM), estimated by C/N ratios and δ 13C values, rapidly decreases with distance from the river mouth. The small vertical variation in δ 13C values of SOM indicates that a fast sedimentation rate overrides the diagenetically determined decomposition. The results obtained indicate that river-borne inorganic particles, natural terrigenous organic material, and anthropogenic metal loads are trapped in sediments of the estuarine system. Under the prevailing conditions, there is no transport towards the open sea.

Clays; Estuary; Geochemistry; Metals; Sediments; Sedimentary Organic Matter

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