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T. Schondorf et al.
known since the 18th century and was named kyanization after the English
chemist, Kyan.
A 5.5% HgCl2 solution was produced on site by the reaction of Hgo and chlorine
gas. The solution was then diluted to 0.66% for use in the basins. The annual
consumption averaged about 11 t of HgCI2 • Turnover balances lead to the
assumption that an amount of ca. 10-20 t of HgCl2 has been released into the
environment over the operational period of five decades. Most of it may have
entered the soil in the area of the sublimate production, in the storage areas for
treated wood, but especially in the application area itself where dip basins and
supply lines were located. Besides quasi-permanent operating losses, e.g.
overfillings, leaky pipelines and basins, individual accidents occurred such as
the bombing of May 1945, fires, which were extinguished partly by using
sublimate, and other reported incidents.
During the 1970S, construction activities for new residential areas were carried
out on the site of the former plant. Today, with regard to residents as well as to
downgradient ground water abstraction for drinking water purposes (the site is
located within a groundwater protection zone for public water supply), the
contamination of the topsoil and the aquifer has to be considered as an acute risk
to human health.
This chapter will describe and discuss some aspects arising within the scope
of:
1. Hg distribution and its compounds in the topsoil is an important factor for Hg
uptake by plants and for direct oral ingestion of contaminated soil by playing
children. The latter is probably the most crucial exposure path for humans.
Therefore, one part of the risk assessment has to take into account the
bioavailabilty of Hg in the soil.
2. On the other hand, profound knowledge about distribution, penetration,
transport and speciation of mercury in subsoil and aquifer will be required in
order to evaluate the risk for the drinking water wells and to develop methods
for the protection or remediation of the groundwater.
Due to the polluter-pays principle, all measures and actions have to be based
on applicable laws and regulations and restricted to officially accepted standards,
like the German DIN. Nevertheless, some promising new methods are supported
by the Land of Baden-Wiirttemberg, like the investigations on Hg bioavailability
or the determination of mercury phases by solid-phase pyrolysis, which cannot
be imposed by legal rights, but are regarded as reasonable by the competent
authorities.
T. Schondorf et al.
known since the 18th century and was named kyanization after the English
chemist, Kyan.
A 5.5% HgCl2 solution was produced on site by the reaction of Hgo and chlorine
gas. The solution was then diluted to 0.66% for use in the basins. The annual
consumption averaged about 11 t of HgCI2 • Turnover balances lead to the
assumption that an amount of ca. 10-20 t of HgCl2 has been released into the
environment over the operational period of five decades. Most of it may have
entered the soil in the area of the sublimate production, in the storage areas for
treated wood, but especially in the application area itself where dip basins and
supply lines were located. Besides quasi-permanent operating losses, e.g.
overfillings, leaky pipelines and basins, individual accidents occurred such as
the bombing of May 1945, fires, which were extinguished partly by using
sublimate, and other reported incidents.
During the 1970S, construction activities for new residential areas were carried
out on the site of the former plant. Today, with regard to residents as well as to
downgradient ground water abstraction for drinking water purposes (the site is
located within a groundwater protection zone for public water supply), the
contamination of the topsoil and the aquifer has to be considered as an acute risk
to human health.
This chapter will describe and discuss some aspects arising within the scope
of:
1. Hg distribution and its compounds in the topsoil is an important factor for Hg
uptake by plants and for direct oral ingestion of contaminated soil by playing
children. The latter is probably the most crucial exposure path for humans.
Therefore, one part of the risk assessment has to take into account the
bioavailabilty of Hg in the soil.
2. On the other hand, profound knowledge about distribution, penetration,
transport and speciation of mercury in subsoil and aquifer will be required in
order to evaluate the risk for the drinking water wells and to develop methods
for the protection or remediation of the groundwater.
Due to the polluter-pays principle, all measures and actions have to be based
on applicable laws and regulations and restricted to officially accepted standards,
like the German DIN. Nevertheless, some promising new methods are supported
by the Land of Baden-Wiirttemberg, like the investigations on Hg bioavailability
or the determination of mercury phases by solid-phase pyrolysis, which cannot
be imposed by legal rights, but are regarded as reasonable by the competent
authorities.