Application of the Chemcatcher‐Metal passive sampler as alternative sampling method for  trace metals in the aquatic environment 

Application of the Chemcatcher‐Metal passive sampler as alternative sampling method for trace metals in the aquatic environment Jördis Petersen1,2, Daniel Pröfrock1, Jose A.C. Broekaert2, Andreas Prange1
Helmholtz‐Centre‐Geesthacht, Institute of Coastal Research, Max‐Planck‐Str. 1, 21502 Geesthacht, Germany, [email protected] 2
University of Hamburg, Department of Chemistry, Inorganic and Applied Chemistry, Martin‐Luther‐King‐Platz 6, 20146 Hamburg, Germany Trace metals are major contaminants in the marine environment due to different input pathways as well as their continuous remobilization from sediments caused by anthropogenic activities. In consequence toxic elements such as Cd, Hg, Ni and Pb are listed as priority substances in the European Water Framework Directive (WFD). Current monitoring approaches are often based on low frequency spot sampling, which provides only snapshot information about the contamination status. A solution to improve the data quality of such monitoring approaches could be the use of passive sampling devices. In comparison to conventional (spot or grab) sampling the application of passive samplers allows the detection of very low contaminant concentrations. Additionally the application of passive sampling devices for trace elements results in a matrix removal, which improves the final analysis in particular when dealing with complex water samples such as sea water. Because of the possibility to sample for a long time period, passive sampling allows the determination of time weighted average concentration of the target contaminants in the water phase, which is often more representative than spot sampling strategies. Due to these interesting features, passive samplers are becoming increasingly importance. In 2011, the European Commission approved a guidance document of the task group on chemical monitoring, in which passive sampling techniques are listed as alternative monitoring tool under the WFD regulations. Additionally an ISO standard (ISO‐5667‐23 2011) has been published in June 2011 dealing with the use of passive sampling in surface waters. The principle of kinetic passive samplers is based on the flux of the analyte from the sampling medium (in our case marine waters) through a diffusion limiting barrier, mostly a membrane, into a receiving phase, which accumulates the analytes. The analyte flux is controlled by a concentration gradient between the sampling medium and the passive sampler. The diffusion process can described by Fick`s first law of diffusion. The Chemcatcher‐Metal consists of a commercial available chelating receiving phase, which builds stabile chelate complexes with divalent or trivalent metal ions using iminodiacetic acid as functional group. A cellulose‐acetate membrane is utilized to control the diffusion process of the metal analytes. Before the Chemcatcher‐Metal could be used in field experiments for measuring free metal ions time‐weighted average water concentrations, calibration laboratory studies are needed to determine the influence of changing field parameters like temperature, pH, water turbulences or salinity on the diffusion process of the analytes through the membrane. Therefore a constant flow‐through exposure system has been developed allowing exposure experiments under field conditions at constant trace metal concentrations. This presentation will focus on the investigation of the influence of varying temperature and water turbulences on the sampling rate of the Chemcatcher‐Metal. Therefore different 14‐days calibration experiments have been conducted followed by the analysis of the trace metal amount of the passive samplers using collision cell ICP‐MS.