Elemental ultra-trace analysis in oceanography

Comprehensive knowledge on the presence and distribution of bioactive metals, e. g. Fe, Al, Cd, Cu, Mn and Zn, in the oceans is of high importance for understanding the entire marine system. International programs such as GEOTRACES are currently studying the biogeochemistry and large-scale distribution of metals and their isotopes in the global marine environment. For the successful accomplishment of a plan like this, analytical techniques are required allowing both, the sensitive and accurate determination of the analytes of interest and a high sample throughput. Aim of the project is the development and optimization of a robust methodological approach for the highly accurate quantification of dissolved metals at ultra-low concentration levels in natural waters based on matrix separation (effective removal of major constituents) and pre concentration of trace metals via solid phase extraction. Important characteristics to be considered within the method development are short cycle times and hence, a high sample throughput and cost effectiveness through full automation of the system for a large number of samples. Main objectives of the project are: Development and implementation of a pre concentration methodology for the analysis of a broad suite of dissolved metals from natural waters Design of an automated high throughput offline pre concentration method for the extraction of the dissolved metals from natural waters Implementation of advanced (isotope dilution based) quantification strategies Application of the developed/optimized pre concentration method on seawater samples Optional method transfer in an online mode with direct coupling to the ICP-MS and the implementation of a simple and rapid approach for transient signal data reduction Amongst the technological and chemical method development, emphasis is also placed on the production of reliable data to be interpreted in a bio geochemical and oceanographic sense to advance our understanding of the way the surface earth works as a biogeochemical system. The proposed research project is planned to be performed at the Ocean Sciences Department of the University of California under supervision of Prof. Kenneth Bruland, who has been deeply involved in the initiation of the international GEOTRACES program. The methodology developed and applied in Prof. Bruland`s research lab will be directly transferred to the BOKU University in Vienna for the accomplishment of upcoming projects dealing with elemental ultra-trace analysis in surface water as currently prepared by Prof. Regina Krachler (University of Vienna) and Prof. Stephan Hann (BOKU University). This will also provide the possibility to cooperate during the return phase following the Schrödinger fellowship.

This project was focused on developing emerging analytical tools for the highly accurate quantification of dissolved metals at ultra-low concentration levels in seawater. Comprehensive knowledge on the presence and distribution of bioactive metals, e. g. iron, copper, manganese, cadmium and zinc in the oceans is of high importance for understanding the entire marine system, thus methods for their determination have been well implemented and international programs such as GEOTRACES are currently studying the biogeochemistry and large-scale distribution of metals and their isotopes in the global marine environment. However, the determination of silver and other precious metals, which are not included in environmental monitoring programs, is showing increasing interest with respect to their concentrations and distributions in oceanic, coastal, estuarine, riverine and ground waters. Given the well-known potential dangers posed by these elements for both natural environments and human health, analytical methods capable of accurately monitoring their distribution in environmental samples are essential. However, precise and accurate quantification of these elements is challenging due to the complex matrices and ultra-low concentrations in the fmol kg-1 and pmol kg-1 range. To address this goal, an advanced and robust methodology capable of selectively and quantitatively analysing silver, palladium, platinum and gold in seawater has been developed based on solid phase extraction of their anionic chloro-complexes utilizing a strong anion exchange resin for matrix separation (effective removal of major constituents) and pre-concentration prior to the determination by inductively coupled plasma - sector field mass spectrometry, to accurately map their distribution in our environment. Main aspects involved with respect to method development were short cycle times and hence, a high sample throughput, cost effectiveness, low hazardous to health with respect to the chemicals used and multi-element capability. The applicability of the method was demonstrated on a suite of reference samples and depth profiles collected during the 2nd U.S. GEOTRACES Intercalibration cruise 2009 in the eastern North Pacific. In a further step, automatization and miniaturization with respect to sample- and reagent volumes and the adaption for the analysis of water samples with varying chloride contents such as high mineralized groundwater samples, the analytical method could also be implemented for national surface- and groundwater monitoring programs. Considering the rapidly increasing use of silver and platinum group elements for medical and industrial applications, an efficient and economical set of analytical methods capable of mapping of elements in the environment at trace- and ultra-trace levels, which is invaluable for our understanding with respect to the environmental fate and eco-toxicological potential is provided.