292
A. Gnamus and M. Horvat
figures lungs, spleen, myocardium and fat tissue concentrations are added. From
the predator species the corresponding tissues were collected for comparison,
except for the brain tissues, endocrine glands and fur, which were not available.
Soft tissues were macerated on sterilized glass plates using a clean scalpel. A
homogeneous mass was obtained and aliquots of the mass sampled for total and
Me-Hg determination. Fur samples were cut into small pieces with a pair of
scissors. Laboratory tools and ware needed for preparation of samples were
washed with an aqueous detergent solution, steamed in hot nitric acid vapour,
rinsed with double distilled Hg-free water and dried. To avoid changes in the
tissue water content the processing of the homogenized animal tissues were
carried out immediately after maceration.
3.2
Determination of Total Mercury (T-Hg)
3.2.1
Soil Samples
T -Hg in soil profile samples was determined by cold vapour atomic fluorescence
spectrophotometry - CV AFS. An aliquot of homogenized soil profile sample
(100 to 300 mg) was digested with 10 ml of an acid mixture (HN0 3 :H2 S0 4 , 7:3 v!
v) in a closed Teflon digestion vessel ("'30 ml) at 70 DC for 4 h. After the
digestion, 1 ml of strong oxidizing solution was added (1 ml of BrCI) and the
sample was diluted to 25 ml with MilliQ water. An aliquot of the digested sample
was then transferred to the reaction vessel containing 20-30 ml of MilliQ water
with 5 ml of HCI and 0.5 ml of SnCl2 to reduce Hg2+ to HgD. The Hg vapour was
then swept from the solution with nitrogen at 450 ml min-' through a soda lime
trap onto gold-coated silica sand. The mercury collected on the trap was then
released into the CV AFS analyzer (Brooks Rand: Model-2) by heating (600 DC)
the trap for 2 min. Peak area integration was used for quantification of Hg (Liang
and Bloom 1993). Some of the soil profile T-Hg contents were also measured by
neutron activation analysis, NAA (Byrne and Kosta 1974).
3.2.2
Plant and Animal Samples
An aliquot of homogenized tissue samples, 150 to 300 mg (dry weight for plant
tissues and wet weight for animal tissues) was carefully weighed and introduced
into a 15-ml Pyrex ampoule and 2 ml of 70% HN0 3 (Merck-MOS Selectipur)
added. Ampoules were sealed and heated at 90 DC for 24 h. The mineralized
samples were diluted with double distilled water (DDW) and the total mercury
(T-Hg) content in aliquots was determined by gold amalgamation cold vapour
atomic absorption spectrometry (CV AASj Horvat et al. 1986) using an LCD
Milton Roy Mercury Detector (Model 1255) and computer-guided reduction!
amalgamation software.
A. Gnamus and M. Horvat
figures lungs, spleen, myocardium and fat tissue concentrations are added. From
the predator species the corresponding tissues were collected for comparison,
except for the brain tissues, endocrine glands and fur, which were not available.
Soft tissues were macerated on sterilized glass plates using a clean scalpel. A
homogeneous mass was obtained and aliquots of the mass sampled for total and
Me-Hg determination. Fur samples were cut into small pieces with a pair of
scissors. Laboratory tools and ware needed for preparation of samples were
washed with an aqueous detergent solution, steamed in hot nitric acid vapour,
rinsed with double distilled Hg-free water and dried. To avoid changes in the
tissue water content the processing of the homogenized animal tissues were
carried out immediately after maceration.
3.2
Determination of Total Mercury (T-Hg)
3.2.1
Soil Samples
T -Hg in soil profile samples was determined by cold vapour atomic fluorescence
spectrophotometry - CV AFS. An aliquot of homogenized soil profile sample
(100 to 300 mg) was digested with 10 ml of an acid mixture (HN0 3 :H2 S0 4 , 7:3 v!
v) in a closed Teflon digestion vessel ("'30 ml) at 70 DC for 4 h. After the
digestion, 1 ml of strong oxidizing solution was added (1 ml of BrCI) and the
sample was diluted to 25 ml with MilliQ water. An aliquot of the digested sample
was then transferred to the reaction vessel containing 20-30 ml of MilliQ water
with 5 ml of HCI and 0.5 ml of SnCl2 to reduce Hg2+ to HgD. The Hg vapour was
then swept from the solution with nitrogen at 450 ml min-' through a soda lime
trap onto gold-coated silica sand. The mercury collected on the trap was then
released into the CV AFS analyzer (Brooks Rand: Model-2) by heating (600 DC)
the trap for 2 min. Peak area integration was used for quantification of Hg (Liang
and Bloom 1993). Some of the soil profile T-Hg contents were also measured by
neutron activation analysis, NAA (Byrne and Kosta 1974).
3.2.2
Plant and Animal Samples
An aliquot of homogenized tissue samples, 150 to 300 mg (dry weight for plant
tissues and wet weight for animal tissues) was carefully weighed and introduced
into a 15-ml Pyrex ampoule and 2 ml of 70% HN0 3 (Merck-MOS Selectipur)
added. Ampoules were sealed and heated at 90 DC for 24 h. The mineralized
samples were diluted with double distilled water (DDW) and the total mercury
(T-Hg) content in aliquots was determined by gold amalgamation cold vapour
atomic absorption spectrometry (CV AASj Horvat et al. 1986) using an LCD
Milton Roy Mercury Detector (Model 1255) and computer-guided reduction!
amalgamation software.