54
R. Ferrara
Hildebrand et al. 1980) from 1974 to 1977 and that reported by Ferrara et al.
(1998a, in press) conducted from 1993 to 1994.
2.2
Main Sources of Atmospheric Mercury
In the remarkable report published by ORNL, the impact of the mining and
refining activity on both terrestrial and aquatic environments is discussed. No
data are, however reported on mercury concentrations in the air and on
atmospheric fluxes from the main sources, probably because of the scarce
analytical methodologies available some 20 years ago. Due to this lack of
information, the field campaigns performed by the Institute of Biophysics
(National Research Council, Italy) and the Lund Institute of Technology (Univ. of
Lund Sweden) were mainly devoted to the determination of mercury emissions,
using both flux chamber (Xiao et al. 1991) and LIDAR techniques developed at
the University of Lund: this laser spectroscopy technique in fact allows a direct
and total valuation of emissions from both spatially extended non-homogeneous
sources and point sources.
A total mercury flux of about 800 g/h was determined above the village of
Almaden (Ferrara et al. 1997) on September 24th 1993 when all the furnaces
were in operation. The most important mercury vapour sources and an
estimate of the mercury emitted from these individual sources present in the
district are:
- stack of the ore-roasting furnaces (~600 g/h),
- area of the refining complex (~lOo g/h),
- roasted cinnabar banks (~80 g/h),
- ventilation systems of the mine (~15 g/h),
- contaminated soil around the Almaden village (~5 g/h).
The total mercury flux from the Almaden district represents around 0.1% of
the present global anthropogenic emission rate (Hudson et al. 1995).
2.3
Mercury in the Air over Almaden
In Fig. 3 the distribution of atmospheric mercury concentration over the
Almaden village is reported together with the position of the sampling stations.
As was predictable, the highest mercury concentrations (20 ~lg/m3) were
measured inside the refining and smelting plant of Almaden (St. 1). Particularly
high values (5 ~lg/m3) were found also close to the ventilation systems of the mine
galleries (Sts. 16, 17, 18). The particular orography of the site and the direction of
the prevailing winds during the summer and autumn months favour the
occurrence of high levels above the village. In the main square (St. 26) values of
the order of 1 ~lg/m3 were often observed. The determinations performed at the
R. Ferrara
Hildebrand et al. 1980) from 1974 to 1977 and that reported by Ferrara et al.
(1998a, in press) conducted from 1993 to 1994.
2.2
Main Sources of Atmospheric Mercury
In the remarkable report published by ORNL, the impact of the mining and
refining activity on both terrestrial and aquatic environments is discussed. No
data are, however reported on mercury concentrations in the air and on
atmospheric fluxes from the main sources, probably because of the scarce
analytical methodologies available some 20 years ago. Due to this lack of
information, the field campaigns performed by the Institute of Biophysics
(National Research Council, Italy) and the Lund Institute of Technology (Univ. of
Lund Sweden) were mainly devoted to the determination of mercury emissions,
using both flux chamber (Xiao et al. 1991) and LIDAR techniques developed at
the University of Lund: this laser spectroscopy technique in fact allows a direct
and total valuation of emissions from both spatially extended non-homogeneous
sources and point sources.
A total mercury flux of about 800 g/h was determined above the village of
Almaden (Ferrara et al. 1997) on September 24th 1993 when all the furnaces
were in operation. The most important mercury vapour sources and an
estimate of the mercury emitted from these individual sources present in the
district are:
- stack of the ore-roasting furnaces (~600 g/h),
- area of the refining complex (~lOo g/h),
- roasted cinnabar banks (~80 g/h),
- ventilation systems of the mine (~15 g/h),
- contaminated soil around the Almaden village (~5 g/h).
The total mercury flux from the Almaden district represents around 0.1% of
the present global anthropogenic emission rate (Hudson et al. 1995).
2.3
Mercury in the Air over Almaden
In Fig. 3 the distribution of atmospheric mercury concentration over the
Almaden village is reported together with the position of the sampling stations.
As was predictable, the highest mercury concentrations (20 ~lg/m3) were
measured inside the refining and smelting plant of Almaden (St. 1). Particularly
high values (5 ~lg/m3) were found also close to the ventilation systems of the mine
galleries (Sts. 16, 17, 18). The particular orography of the site and the direction of
the prevailing winds during the summer and autumn months favour the
occurrence of high levels above the village. In the main square (St. 26) values of
the order of 1 ~lg/m3 were often observed. The determinations performed at the