260
V. MiklavCic
mass poisoning, permanent injuries and deaths that occurred in Japan,
Minamata (1956) and Niiagata (1965), and in Iraq (1972) as a result of the
negligent use of Hg preparations. At the end of the 1960s, reports of increased Hg
content in birds and some types of fish were published in Sweden (Johnels and
Westermark 1969). The above-mentioned disasters and findings met with a
worldwide response, resulting in limitation of the further production and broad
industrial use of this unique liquid metal. The Hg crisis and falling demand (and
price) led to a decision on the gradual shutdown of the Idrija Mine, which was
passed by the Slovene Assembly in 1987. It was foreseen that the mine would be
gradually shut down by 2006 and that monitoring of the consequences of the
shutdown process would be conducted until 2009.
Mass poisonings with organic Hg compounds triggered numerous internationally coordinated studies of the harmful effects of Hg on the environment, its
toxic effects on living organisms and the transformation of inorganic Hg into
more toxic organic Hg forms, particularly methylmercury. In the early 1970S
(1969-1974), when Hg production in the Idrija Mine was at its peak, the research
group of the Department of Nuclear Chemistry at the J. Stefan Institute, headed
by Prof. Lado Kosta, in collaboration with the Research Unit of the Idrija
Mercury Mine, began intensive studies of the Hg ecological cycle in the Idrija
region. These studies, which were undertaken as a response to the previously
mentioned contamination with mercury compounds and based on the fact that
Idrija and its immediate surroundings offered an ideal location for studies of this
kind, involved monitoring of uptake, spread and transformation processes of Hg
in the Idrija region, with the objective of determining the health hazards existing
in the area due to the presence and harmful effects of Hg. These studies were of
great importance at that time, which is evident from the fact that similar studies
undertaken at the Almaden Mercury Mine, with the strong financial support of
the University of Rochester, were in their initial phase in 1974.
The studies dealt with Hg circulation in practically all ecological systems and
were complemented by the development and upgrading of analytical methods for
determining sub microgram quantities of Hg in a broad range of samples from
the area, as well as methods for tracing other Hg compounds. New techniques
and improved methods for determining the total Hg content and methylmercury
(MeHg) content were introduced in order to study the uptake and distribution of
this element in the ground, air, water, plants, animals and man. The analytical
methods used were based on neutron activation and volatilization of mercury
under specific conditions (Kosta and Byrne 1969; Byrne and Kosta 1974), gas
chromatography of volatile organic Hg compounds (Zelenko and Kosta 1973),
and in the determination of mercury values in air by fiameless atomic absorption
(Kosta et al. 1974).
Mining activities, the roasting of ore and the use of ore residues, as well as the
naturally increased Hg content in the ground have heavily contaminated Idrija
and its surroundings with Hg. The Idrija ore deposit contains rocks enriched
with cinnabar originating from periods up to Middle Triassic. Native Hg can be
found primarily in Carboniferous clastic rocks which reach the surface in the
western part of the ore deposit in the so-called Pront area (Mlakar 1974). The
hazard of Hg contamination to humans and the environment increased during
V. MiklavCic
mass poisoning, permanent injuries and deaths that occurred in Japan,
Minamata (1956) and Niiagata (1965), and in Iraq (1972) as a result of the
negligent use of Hg preparations. At the end of the 1960s, reports of increased Hg
content in birds and some types of fish were published in Sweden (Johnels and
Westermark 1969). The above-mentioned disasters and findings met with a
worldwide response, resulting in limitation of the further production and broad
industrial use of this unique liquid metal. The Hg crisis and falling demand (and
price) led to a decision on the gradual shutdown of the Idrija Mine, which was
passed by the Slovene Assembly in 1987. It was foreseen that the mine would be
gradually shut down by 2006 and that monitoring of the consequences of the
shutdown process would be conducted until 2009.
Mass poisonings with organic Hg compounds triggered numerous internationally coordinated studies of the harmful effects of Hg on the environment, its
toxic effects on living organisms and the transformation of inorganic Hg into
more toxic organic Hg forms, particularly methylmercury. In the early 1970S
(1969-1974), when Hg production in the Idrija Mine was at its peak, the research
group of the Department of Nuclear Chemistry at the J. Stefan Institute, headed
by Prof. Lado Kosta, in collaboration with the Research Unit of the Idrija
Mercury Mine, began intensive studies of the Hg ecological cycle in the Idrija
region. These studies, which were undertaken as a response to the previously
mentioned contamination with mercury compounds and based on the fact that
Idrija and its immediate surroundings offered an ideal location for studies of this
kind, involved monitoring of uptake, spread and transformation processes of Hg
in the Idrija region, with the objective of determining the health hazards existing
in the area due to the presence and harmful effects of Hg. These studies were of
great importance at that time, which is evident from the fact that similar studies
undertaken at the Almaden Mercury Mine, with the strong financial support of
the University of Rochester, were in their initial phase in 1974.
The studies dealt with Hg circulation in practically all ecological systems and
were complemented by the development and upgrading of analytical methods for
determining sub microgram quantities of Hg in a broad range of samples from
the area, as well as methods for tracing other Hg compounds. New techniques
and improved methods for determining the total Hg content and methylmercury
(MeHg) content were introduced in order to study the uptake and distribution of
this element in the ground, air, water, plants, animals and man. The analytical
methods used were based on neutron activation and volatilization of mercury
under specific conditions (Kosta and Byrne 1969; Byrne and Kosta 1974), gas
chromatography of volatile organic Hg compounds (Zelenko and Kosta 1973),
and in the determination of mercury values in air by fiameless atomic absorption
(Kosta et al. 1974).
Mining activities, the roasting of ore and the use of ore residues, as well as the
naturally increased Hg content in the ground have heavily contaminated Idrija
and its surroundings with Hg. The Idrija ore deposit contains rocks enriched
with cinnabar originating from periods up to Middle Triassic. Native Hg can be
found primarily in Carboniferous clastic rocks which reach the surface in the
western part of the ore deposit in the so-called Pront area (Mlakar 1974). The
hazard of Hg contamination to humans and the environment increased during