Evolution and biogeochemical cycles of metal species in marine and lacustrine environments

1995/96
Characterization of minor and trace metals in lacustrine ecosystems (Carezza
Lake, Inexpressible Island, Tarn Flat, Edmondson Point). Determinations in
lake waters, sediments, algae and soil. The scientific objectives achieved were
the completion of the yearly temporal sequence and the prosecution of the
collection of historical series of data on the concentrations of minor, trace
and ultratrace metals in samples from lacustrine ecosystems, with the aim of
acquiring information on the distribution among water, soil, algae and
sediments and on their biogeological cycles. The data obtained allow to outline
interesting correlations among the variations of the various investigated
elements, which will become more evident after including the data from the
subsequent sampling campaigns. Sampling of surface water from Gerlache Inlet.
As to seawater samples, we studied the temporal profiles of metal
concentrations with particular regard to the effect of the presence and melting
of ice-pack. Such variations are discussed taking into account the different
chemical forms in which the considered elements are distributed in the
investigated ecosystems.

1996-97
Distribution of pollutants in marine and lacustrine matrices. During the
1996-97 Campaign, no samples were collected either from coastal or open
seawater, or from the lakes investigated during the previous campaigns. The
measurements and determinations on the samples collected during the 1994-95 and
1995-96 Campaigns were completed.

1997-98
Our research activities were aimed at the determination of trace and ultratrace
metals in seawater from Gerlache Inlet and other areas of the Ross Sea. In
particular, we examined samples collected in Gerlache Inlet at different depth
and periods, and depth profiles from six different parts in the open sea and
discussed the temporal and spatial variations observed. The results obtained
were treated with multivariate techniques. As to Carezza Lake, Tarn Flat and
Edmonson Point, the following matrices were samples: water, algae, sediments
and soil from the surroundings of the lakes. The scientific objectives achieved
were again the implementation of yearly temporal sequences of minor, trace and
ultratrace metal determinations in samples collected from the lacustrine
ecosystems, in order to obtain information on the distribution of heavy metals
among water, sediment, soil and algae.

1998-99
Our Operative Unit received samples of surface seawater obtained with the new
device for the collection of surface microlayer. The samples were obtained in
Gerlache Inlet, from which water was collected also in the previous Campaign.
Such samples allow to characterize the enrichment, which takes place also for
metal species, in the marine surface microlayer. Moreover this third year of
activity within the period 1996/99 was dedicated to the completion of the
numerous determinations on samples of lacustrine and marine matrices. We
finished the sets of measurements, already partially carried out, on the
samples collected on the previous campaigns and analyzed the specimen collected
in the 1997/98 campaign. Afterwards, the data obtained were treated with
statistical techniques, in order to obtain as much information as possible.
Moreover, many samples of lacustrine matrices were collected for our Operating
Unit from Carezza Lake. Such samples were analyzed for metal species in order
to prosecute the collection of the yearly temporal sequence of data for
lacustrine ecosystems.

1999/2000
No samplings were performed for our Research Unit, and our activities were
directed mainly to the completion of the analyses of the samples collected in
the previous campaigns.

2000/01
We received samples of seawater sampled from three different depth profiles,
named CA, CA2 and D1. Profiles CA and CA2 are located near Adare Cape, while
profile D1 is located in the polynya zone near Drygalsky Glacier, which
represents one of the most important zones for the formation of high density
waters. Also for these results statistical analyses have been completed in
order to obtain the highest number of information obtainable. In addition
samples of the marine superficial microlayer have been analyzed, sampled from
Gerlache Inlet, and their concentrations were compared with those obtained from
the corresponding subsuperficial layers. For the lacustrine environment,
prosecuting the continuous activities of our Research Unit, we received samples
of the various matrices from Carezza lake (lake water, algae, sediment).

2001/02
Considering that the 2001/2002 campaign involved activities mainly centered on
Terra Nova Bay, coastal seawater samples from Gerlache Inlet were analyzed,
along three vertical profiles (one for each of the three different periods of
the campaign), constituted by four different samples (corresponding to the
surface, the maximum of fluorescence, the thermocline, and the bottom
vicinity). The determinations regarded the concentration of minor and trace
metals. For what regards the lacustrine environment, samples from Carezza lake
were investigated for the determination of metals in water, surrounding soil,
in algae, in sediment. The samples were collected in two different periods:
corresponding to the melting of the ice covering the lake and in a second
period before the closure of the campaign.

2002/03
Taking into account that the activities in Antarctica during the expedition
2002/2003 involved the participation of the Chemical Contamination Sector to
the oceanographic campaign in Ross Sea, our Research Unit took part to the
characterization and to the study of the modifications that oceanic water
masses undergo in the proximity of Antarctica. For this reason we received
seawater samples, for investigating the distribution and the variation of metal
species, with particular regard to the metal traces Cd, Cu, Fe, Mn, Ni, for
characterizing their modifications in different locations of Ross Sea and along
vertical sampling profiles. In addition to these, other elements, present in
higher concentration, have been investigated in order to monitor physical
phenomena and variations involving conservative quantities. Such determination
were directed to the study of the effects of the interaction of the waters from
the Circumpolar Deep Water current with the Ross Ice-Shelf. For characterizing
the interactions and fluxes of the above mentioned waters the distributions
along vertical profiles were investigated in the proximity of Cape Adare, along
the route of the High Salinity Shelf Water towards Cape Adare, in the zone of
formation of the Ice Shelf Water (point F) and in the zone of the mooring
(points H1 and H2). Finally, since our Research Unit pointed out that the
concentrations of the major, minor and trace metals are higher in the lake
water samples collected at the end of the antarctic summer in comparison to
those sampled at the beginning of the summer season, we received for this
campaign two water samples collected from Carezza Lake at the beginning of the
thaw (31/12/2002) and at the end of the antarctic campaign in order to verify
the existence of a temporal trend of the metal concentrations in antarctic
lakes. With reference to this lake we received also a sample of sediment and of
algae.

2003/04
With reference to the lacustrine environment samples from the lakes
Inexpressible Island, Tarn Flat, Edmonson Point were collected. The samples
were analyzed for determining metals in water, surrounding soil, sediment,
algae. For Tarn Flat and Inexpressible Island lakes we determined the metal
content also in the suspended particulate matter. For the marine environment,
the Research Unit received one sediment core taken near the Hells Gate Ice
Shelf and one taken in open ocean near one of the canyons through which shelf
waters flow towards the deepest depths of the Ross Sea.