AISIT - a new device for remote-controlled sampling of dissolved and particle-bound trace elements in surface waters

An automatic sampling device for water samples (AISIT = automatic intellige nt water sampler for inorganic trace constituents) was developed by the Bec field Company (Isernhagen, Germany) and the GKSS Research Centre within the Euromar Mermaid project. The sampler permits remote-controlled and event-c ontrolled collection of water samples and performs a separation of the diss olved and the particulate phases immediately after sampling. Twenty-four wa ter samples can be collected and assigned to events such as time, tide, cur rent or turbidity. Samples are filtered directly after sampling through 0.4 0 mu m polycarbonate filters and stored for further analysis. Tests on func tionality, modifications of material and improvements in performance were c arried out in the laboratory. Additional effort was exerted to achieve cont amination-free samples and to extend the deployment time of the system. Det ermination of Cd, Cr, Cu, Fe, Mn, Ph and Hg in suspended matter was perform ed by atomic absorption spectrometry (AAS), total-reflection X-ray fluoresc ence spectrometry (TXRF) and inductively coupled plasma-mass spectrometry ( ICP-MS) after digestion with nitric acid. Cd, Pb and Cu in the water column were analysed by anodic stripping voltammetry (ASV). Samples collected wit h a GoFlo water sampler agreed well with samples taken by the AISIT system even at ultra-trace levels in the open sea. The AISIT sampler allows effect ive and systematic research on the behaviour and the transport of trace met als. Daily sampling in the Elbe estuary during a high freshwater discharge event demonstrated the importance of an adaptive sampling strategy to inves tigate the transport of the trace elements from the Elbe River into the Nor th Sea. Measurements directly after a high freshwater event showed that par ticle-hound metals were effectively transported into the coastal zone. (C) 1998 Elsevier Science B.V. All rights reserved.