Transport and Chemodynamics of Trace Elements in Freshwater and Coastal Sedimentary Systems (TRACESS)
Why do we need TRACESS?
The Planet Earth is a blue planet – with 70 % of its surface covered by oceans and 40 % of the World’s population living within 50 km of a coastline, our heritage, economy and wellbeing are inextricably linked with the marine environment. Lacustrine, estuarine, pericoastal and near-shore marine sediments often contain valuable records of sediment yield history and contaminant transport spanning timescales from decades to millennia. Nevertheless, there are still important gaps in the understanding of the transport of elements in aquatic media and sediment accumulation in diverse but sensitive environments. Although most sediments, by their nature, preserve only a partial record, they may provide a valuable source of data for reconstructing trends in sediment and sediment-associated contaminant transport where long-term sediment monitoring programs are not available. Consequently, in the efforts to evaluate the quality of aquatic habitats and potential threats to human population due to pollution the study of the river suspended materials is becoming more important.
The aim of the proposed project entitled "Transport and Chemodynamics of Trace Elements in Freshwater and Coastal Sedimentary Systems" (TRACESS) is to increase our understanding of the biogeochemical cycles that are important for freshwater and coastal sedimentary systems in karstic areas, using specific groups of elements i.e. anthropogenic and bioactive (Cd, Co, Cr, Cu, Mn, Ni, V, Zn), rare earth elements (REE), redox sensitive elements, toxic elements and compounds (organotin compounds) which were chosen to represent different biogeochemical environments where a suite of geochemical processes can be traced. Sideline research will involve balneochemical investigations of peloid producing environments in pristine and anthropogenically impacted locations along the eastern Adriatic coast.
The composition of aquatic sediment depends on the provenance of sediments, the transport path and the distance to the depositional basin. One of the important objectives of this project will be to study transport of elements in different types of aquatic systems (rivers, estuaries, lakes). Particularly, the role of transport of trace elements on suspended particles will studied, as most of the trace elements are transported mainly in association with particulate phase. Chosen aquatic systems will enable to compare transport processes in polluted and unpolluted environments as well as in rivers, where the horizontal transport and processes are significantly influenced by the river flow, and in lakes where vertical transport of particles is a key process.
Within the frame of this project the geochemistry of trace elements in different freshwater and marine sedimentary systems will be investigated, with emphasis on using different trace elements, or groups of elements (i.e. rare earth elements), in order to elucidate the most important reaction pathways and processes in each system. Particular attention will be paid to the assessment of anthropogenic impacts of toxic metals. Each of the chosen system has its specific characteristics providing environments suitable for investigations of various elemental proxies.
The Mljet lakes are small marine lakes on the island of Mljet which provide an excellent natural model system for investigating the influence of redox gradients in the sediment and bottom water on the geochemical behavior of redox-sensitive elements, their mobility and fluxes to and from the sediment. Elements like Fe, Mn, Mo or U are especially interesting in this respect as they can serve as paleoproxies for reconstructing redox condition in the water column at the time of deposition.
The Novigrad Sea is a karstic estuarine system surrounded by several bauxite deposits (including a now decommissioned aluminum plant). It presents an ideal system for studying the distribution of rare earth elements in estuaries and the processes governing it, as well as the applicability of the use of their concentrations and distribution patterns in sediments as a means of monitoring anthropogenic impacts.
The Neretva river delta, a karstic, microtidal, low-energy deltaic sedimentary system, presents an opportunity to study geochemical processes that govern deposition and distribution of sediments and trace metals under changing estuarine conditions.
Anthropogenic influences (particularly marine traffic and fish farming) on the aquatic systems will be studied and evaluated. Sediments from the coastal area, sampled in areas which are contaminated with TBT (marinas and harbours), will be used to investigate decomposition rates of butyltin compounds and estimate their persistence and consequently their long-term influence on the coastal environment.
The geochemical behavior of elements in freshwater environments will be studied in two largely unpolluted systems located in the Plitvice lakes and the Krka river National Parks, as well as the Sava river which is under significant anthropogenic pressure. In those systems distribution of elements between dissolved and particulate phases will be studied, with a special emphasis on the role of transport of elements on suspended particles and the removal of metals from the water column into sediment.
Study of balneochemical characteristics of peloids will provide relevant information on resources which can be used for health tourism, this being in close agreement with national priorities for scientific research (environment and health).
New analytical methods for element speciation in environmental matrices will be also developed, particularly for elements like Cr, As or Sb for which toxicity depends on the chemical form and determination of the total concentration is not sufficient.
The results of the implementation of this project should be of value to various stakeholders (i.e. educational institutions, ministries and authorities responsible for the protection of the environment and nature, wellness tourism initiatives, environmental-forensic science units, environmental-law enforcement bodies, agencies involved in environmental monitoring programs, water-management authorities, aquaculture enterprises and civilian communities).