Evidencing the natural and anthropogenic processes controlling trace metals dynamic in a highly stratified estuary: The Krka River estuary (Adriatic, Croatia)

Abstract

Distributions of trace metals (TM), organic carbon, SPM and physico-chemical parameters were studied in the highly stratified Krka River estuary in winter/summer periods. The nonconservative behaviour of Zn, Cd, Pb and Cu in the brackish layer (plume), easily spotted due to very low inputs by the river, was mainly caused by their inputs from the pleasure boats, nautical marinas and harbour (e.g. release from antifouling paints). Contrarily, Ni and Co followed near-conservative behaviour. The extremely low SPM discharged by the river,

Evaluation of Discrete and Passive Sampling (Diffusive Gradients in Thin-films – DGT) Approach for the Assessment of Trace Metal Dynamics in Marine Waters – a Case Study in a Small Harbor

“…The specific measurement procedures followed published protocols. [2] Concentrations of trace metals were determined by means of standard addition method. A certified "Seawater Reference Material for Trace Metals" -NASS-5 (NRC CNRC) was used for validation of the analysis.…”

“…[8,33] Effective diffusion coefficients (determined in separate controlled experiments) operational for brackish/seawater conditions were used for all calculations. [2,34] Error bars in figures represent the upper and the lower measured dissolved metal concentrations for that deployment period (samples taken at the beginning and at the end of deployment period) and/or DGT-labile concentrations of metals measured in each of the two DGT devices. If not visible, error bars are within the size of the symbol.…”

“…They can enter into the aquatic system through erosion processes, [1] but could be also released by different human activities that have great impact on coastal areas and can directly or indirectly contribute to contamination. [2][3][4] In natural waters, trace metals exist in different physical forms and chemical species, which regulate their biogeochemical cycle [5] as well as their potential toxicity for organisms. Due to the complexity of the aquatic environment, the speciation of trace metals is a very challenging, and different approaches have been applied.…”

“…[5][6][7][8] The most common approach providing sufficient information to understand general behavior of trace metals distribution is based on discrete sampling and the measurement of dissolved and total metal concentrations. [2,4,9] However, for a greater understanding of the behavior and the interactions of trace metals with other constituents (including biota), specific techniques were developed and widely applied, providing valuable information on the trace metal speciation. [6,[10][11][12][13][14][15][16][17] Bioavailability of trace metals is of primary concern when considering if trace metals serve as nutrients or as toxicants.…”

“…[30] In shipyards, harbors and marinas local sources of contamination are Cu and Zn stemming from paint waste. [2,31,32] The purpose of this study is to evaluate a multimethodological approach, consisting of classical discrete grab sampling, passive sampling using DGT technique and a chemical speciation modeling, for the assessment of the spatial and temporal distribution, as well as the operational speciation of trace metals in a small harbor (Sušak port in Rijeka harbor, Croatia, Adriatic Sea) having various transshipment activities and which is also under permanent influence of freshwater inflow receiving various forms of waste.…”