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Die Bestimmung und überwachung von Quecksilber in der Umwelt ist


Die Bestimmung und überwachung von Quecksilber in der Umwelt ist

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									Design and deployment of automated FI instrumentation for in the situ
determination of mercury in natural waters

Keywords: Mercury speciation; atomic fluorescence; preconcentration; Tamar estuary.

Personnel: Paul Worsfold and |Mike Foulkes (supervisors), Kirsten Leopold (Postdoctoral

Funding body: Bayerische Forschungsstiftung

Project duration: April 2008 – November 2008-05-20

The worldwide risk assessment of mercury in the environment is of great interest. The
European Union lists mercury as one of the 33 priority pollutants and therefore its
monitoring in the hydrosphere is regulated by law. However, analytical methods used for
the routine determination of mercury at the ultra-trace level (pg l-1 to ng l-1 range) in natural
waters (cold vapour – atomic fluorescence / absorption spectrometry; CV-AFS, CV-AAS)
have significant drawbacks: They are time consuming, require a lot of manual process
steps, use many reagents, some of which are extremely toxic and have high blank values
due to reagents, storage and sampling procedures.
Therefore, the aim of this research project is to develop a flow-injection analysis system
(FIAS) for the simple and rapid determination of total dissolved mercury in natural waters.
It is based on the separation and enrichment of mercury on a catalytically active nano-gold
surface directly from the aqueous sample. For sensitive detection of mercury the
enrichment column is dried and heated to release mercury vapour into the flow-through
cell of an atomic fluorescence spectrometer (AFS). The direct enrichment of dissolved
mercury species from the aqueous sample has several advantages compared with
standard methods: No reagents are necessary for decomposition or cold vapour
generation; low contamination risk; fully automated system and therefore useful for
shipboard and other in situ monitoring. First investigations of real seawater samples with
the newly developed FI method are very promising.
The emphasis will be on the construction and deployment of automated FI instrumentation
for the in situ determination of mercury in natural waters, i.e. outside the laboratory. A
second aim will be to map the distribution of mercury in the Tamar catchment by shipboard
and/or bankside deployments in order to provide immediate, high quality analytical
information with good temporal and spatial resolution. This could enable detection of
trends in the distribution of mercury and transient events such as pollution incidents. The
obtained set of data – dissolved mercury concentrations in seawater, estuary, rivers and
other freshwaters – could be enhanced by measuring in addition other important
parameters, e.g. temperature, salinity, dissolved organic carbon, mercury bound to
particles/colloids, etc. Interpretation of the data sets should help to increase our knowledge
of mercury biogeochemistry in the aquatic system.

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