CHAPTER 14
Mercury Concentrations in Sea Water Sampled with the New "Marikiki"
Sampler
R. Capelli, V. Minganti, and R. De Pellegrini
ABSTRACT
During a series of oceanographic cruises (December 1993, June 1994, December 1994, and July
1997) in the area of the buoy IIODAS Italia 1" in the Ligurian Sea (43
0
48.90'N 09° 06.80'E), a new
sampling bottle for deep sampling of sea water for trace metals analysis at nglilevel was tested.
The reactive mercury concentration was determined directly on board the oceanographic vessel,
immediately after the sampling by reduction with tin (II) chloride, pre-concentration on gold, and
atomic fluorescence detection. Mercury concentrations ranged between 0.06 and 0.90 nglL with
an average of 0.22 ngll for samples collected in December 1993,June and December 1994. Higher
values were found (mean 0.41 ngll, range 0.27-0.61 ng/l) in samples collected in July 1997.
Introduction
In order to investigate the biogeochemical cycle
of mercury, the concentration of both organic
and inorganic forms of the metal in all components of the ecosystem (air, water, organisms and
sediments) must be determined. In the environment mercury concentrations range from ng/m3
(air) to ngll (water) to ~g/g (organisms and sediments), and different analytical methods with
the required sensitivity and accuracy have been
developed.
As far as sea water is concerned, mercury is
present at concentrations of a few ng/I or even
less. Regarding the Mediterranean, there are data
for the presence of mercury at the surface
(Ferrara and Maserti 1986; Copin-Montegut et al.
1986; Minganti et al. 1993), but very few data on
mercury concentrations at different depths
(Cossa et al. 1997; Ferrara and Maserti 1988).
At present, determination of pg or ng of mercury has been made possible by highly sensitive
analytical methods such as atomic fluorescence
and atomic absorption spectrometry and preconcentration on metals such as silver and, especially, gold. However, there are still some difficulties connected with the purity of reagents and of
all materials used during the sampling. storage
and analytical procedures. It is possible to
choose materials and reagents that allow to
reduce sample contamination to a minimum,
while sampling remains the most difficult procedure, particularly if it has to be carried out at
depths in excess of 10-15 metres.
After examining the various available equipment to sample sea water at different depths, a
new sampling device was designed and tested
which combines a simple sampling procedure
with the possibility to obtain contamination-free
samples (Capelli et aI. 1998). With this sampling
equipment a series of sea water samples have
been collected at different depths, near the buoy
ODAS Italla -1, in the Ligurian Sea, in order to
verify if reactive mercury concentrations can be
used as a tracer of the different water masses.
Materials and Methods
Sampling
Sea water samples were collected during offshore investigations carried out in December
1993, June 1994, December 1994 and July 1997 in
co-operation with C.N.R. (Italian National
Research Council) on board MIV Urania. The
Dipartimento di Chimica e Tecnologie Farmaceutiche ed Alimentarl, Universita di Genova, Via Brlgata Salerno, 16147 Genova,
Italy
P.M. Faranda, L. Guglielmo. G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
© Springer-Verlag ltaIia 2001
Mercury Concentrations in Sea Water Sampled with the New "Marikiki"
Sampler
R. Capelli, V. Minganti, and R. De Pellegrini
ABSTRACT
During a series of oceanographic cruises (December 1993, June 1994, December 1994, and July
1997) in the area of the buoy IIODAS Italia 1" in the Ligurian Sea (43
0
48.90'N 09° 06.80'E), a new
sampling bottle for deep sampling of sea water for trace metals analysis at nglilevel was tested.
The reactive mercury concentration was determined directly on board the oceanographic vessel,
immediately after the sampling by reduction with tin (II) chloride, pre-concentration on gold, and
atomic fluorescence detection. Mercury concentrations ranged between 0.06 and 0.90 nglL with
an average of 0.22 ngll for samples collected in December 1993,June and December 1994. Higher
values were found (mean 0.41 ngll, range 0.27-0.61 ng/l) in samples collected in July 1997.
Introduction
In order to investigate the biogeochemical cycle
of mercury, the concentration of both organic
and inorganic forms of the metal in all components of the ecosystem (air, water, organisms and
sediments) must be determined. In the environment mercury concentrations range from ng/m3
(air) to ngll (water) to ~g/g (organisms and sediments), and different analytical methods with
the required sensitivity and accuracy have been
developed.
As far as sea water is concerned, mercury is
present at concentrations of a few ng/I or even
less. Regarding the Mediterranean, there are data
for the presence of mercury at the surface
(Ferrara and Maserti 1986; Copin-Montegut et al.
1986; Minganti et al. 1993), but very few data on
mercury concentrations at different depths
(Cossa et al. 1997; Ferrara and Maserti 1988).
At present, determination of pg or ng of mercury has been made possible by highly sensitive
analytical methods such as atomic fluorescence
and atomic absorption spectrometry and preconcentration on metals such as silver and, especially, gold. However, there are still some difficulties connected with the purity of reagents and of
all materials used during the sampling. storage
and analytical procedures. It is possible to
choose materials and reagents that allow to
reduce sample contamination to a minimum,
while sampling remains the most difficult procedure, particularly if it has to be carried out at
depths in excess of 10-15 metres.
After examining the various available equipment to sample sea water at different depths, a
new sampling device was designed and tested
which combines a simple sampling procedure
with the possibility to obtain contamination-free
samples (Capelli et aI. 1998). With this sampling
equipment a series of sea water samples have
been collected at different depths, near the buoy
ODAS Italla -1, in the Ligurian Sea, in order to
verify if reactive mercury concentrations can be
used as a tracer of the different water masses.
Materials and Methods
Sampling
Sea water samples were collected during offshore investigations carried out in December
1993, June 1994, December 1994 and July 1997 in
co-operation with C.N.R. (Italian National
Research Council) on board MIV Urania. The
Dipartimento di Chimica e Tecnologie Farmaceutiche ed Alimentarl, Universita di Genova, Via Brlgata Salerno, 16147 Genova,
Italy
P.M. Faranda, L. Guglielmo. G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
© Springer-Verlag ltaIia 2001