Maria Luisa Abelmoschi

Temporal distribution of trace metals in Antarctic coastal waters

Abstract In the framework of the Italian Research Programme in Antarctica, a nearshore station positioned inside the Gerlache Inlet (Terra Nova Bay, Western Ross Sea) was regularly sampled during the Austral Spring 1997/1998, from November to February. In order to evaluate the physical, chemical and biological variations along the water column, measurements of a large number of parameters were performed at a suitable frequency: temperature, salinity, fluorescence, suspended particulate matter, concentration of dissolved and particulate Fe, Cu and Mn, concentration of nutrients and phytoplankton pigments. Samples of pack ice and marine microlayer were also collected and analysed. Elaboration of data with regards to temporal and vertical components provided a good description of temporal distribution of trace metals in the coastal waters of Terra Nova Bay, in relation to the physical and biological processes. Concerning the surface layer, it was found that concentrations are mainly affected by the dynamic of the pack ice melting and phytoplankton activity. The first process influences both the input of metals from meltwaters and the covering of the seawater surface, allowing atmospheric dust input only when all ice has been melted or removed. Direct release from ice of particulate Fe and Cu were clearly shown by surface concentration peaks and by the high concentrations of suspended particulate matter and particulate metals detected in the ice core section interfaced with the seawater. Moreover, a quite complex dynamic dissolved/particulate partitioning was found, which can account for the temporal uncoupling between the maximum values of particulate and dissolved metals. In absence of pack ice, there is evidence of a further input of Fe and Mn due to atmospheric dust brought into the water column through the marine microlayer. This picture is complicated by phytoplankton activity, which removes micronutrients like Fe and Cu from water, incorporating them into organic particulate matter. The dynamic of metal uptake follows that of primary production which, in the studied area, shows a specific trend characterised by two distinct blooms: the first in the second half of December and the second in late summer. In intermediate and deep waters, the vertical distribution of Fe and Mn was characterised by a substantial constant profile until January; then, an increase of particulate metal concentration with depth was observed along with a corresponding decrease of the dissolved concentrations. This trend is typical of these scavenging-type elements which are removed by particulate matter during the sinking process, in the absence of well-defined water column stratification.

Effects of Ice Melting on Cu, Cd and Pb Profiles in Ross Sea Waters (Antarctica)

Abstract In the framework of the Italian Research Programme in Antarctica, evolution of dissolved and particulate Cu, Cd and Pb profiles in the coastal waters of Gerlache Inlet (Terra Nova Bay, Western Ross Sea) was studied during the Austral Summer 1997/98. In order to relate the distributions of trace metals with the physical and biological processes, a series of temperature and salinity measures were made, and water samples were collected to determine nutrients and chlorophyll. Samples of pack ice and marine microlayer (50–150 μm) were also collected and analysed. Concerning the surface layer, it was found that metal concentrations are mainly affected by the dynamic of the pack ice melting and phytoplankton activity. The first process influences both the input of metals from meltwaters and the covering of the seawater surface, allowing atmospheric dust input only when all ice has been melt or removed. Direct release of particulate Cu from ice was clearly shown by surface maxima and by the high concentrations of suspended particulate matter and particulate metals found in the ice core section interfaced with the seawater. Differently, the high amount of Cd in the particulate included in the pack ice seems not to affect the concentration in surface particulate; on the contrary, the corresponding increase of dissolved Cd indicates that it isreleased in dissolved form when the pack ice melts. Surface distribution is further complicated by the effect of phytoplankton activity, which removes Cu and Cd from water, incorporating them into organic particulate. Finally, in absence of pack ice, there is evidence of inputs of Pb and Cu due to atmospheric dust brought into the column water through marine microlayer. In intermediate and deep waters, the vertical distribution of Pb and Cd was characterised by substantially constant profiles, while Cu shown, during the end of the summer and in absence of a well-defined water column stratification, a “scavenging-type” distribution which overlaps its “nutrient-type” behaviour.

Determination of Trace Metals in Antarctic Sediments from Terra Nova Bay - Ross Sea

Abstract Trace metals (Cu, Pb, Zn, Cd, Cr, Ni, Co, Mn) and iron concentration were determined in several sediments collected in the Antarctica (Terra Nova Bay—Ross Sea). Samples were analyzed by inductively coupled plasma (ICP-AES) after selective and total extraction. The results are in good agreement with the data previously collected in the same area.

Determination of trace metals in sea-water by electrothermal atomic absorption spectrometry following solid-phase extraction: quantification and reduction of residual matrix effects

The use of an iminodiacetic resin for trace metal preconcentration from sea-water does not allow a complete removal of the matrix, since significant amounts of alkali and alkaline earth elements are retained by the resin and co-elute with the analytes. The interfering effects due to sodium, potassium, calcium and magnesium on the electrothermal atomization of cadmium, lead, copper, iron and manganese were studied in a multivariate way. The adopted method allowed both an accurate quantification of the signal variations due to the matrix elements and a prediction of the analytical error in the determination by electrothermal atomic absorption spectrometry. In order to reduce the interfering effects, two different approaches were considered: chemical modification and matrix separation by pre-elution with ammonium acetate. A significant decrease of the interfering effects was observed for copper, lead and cadmium, after optimization of the thermal programs and proper choice of the chemical modifier. Differently, strong signal variations caused by the matrix were observed for iron and manganese, for each condition. Matrix separation by selective elution with ammonium acetate was more effective, allowing the complete suppression of matrix effects for all the considered elements. The results were confirmed by the analyses of the sea-water reference materials CASS-3 and NASS-5.

Reduction of interferences in graphite furnace atomic absorption spectrometry by multiple linear regression modelling

Abstract The multivariate effects of Na, K, Mg and Ca as nitrates on the electrothermal atomisation of manganese, cadmium and iron were studied by multiple linear regression modelling. Since the models proved to efficiently predict the effects of the considered matrix elements in a wide range of concentrations, they were applied to correct the interferences occurring in the determination of trace elements in seawater after pre-concentration of the analytes. In order to obtain a statistically significant number of samples, a large volume of the certified seawater reference materials CASS-3 and NASS-3 was treated with Chelex-100 resin; then, the chelating resin was separated from the solution, divided into several sub-samples, each of them was eluted with nitric acid and analysed by electrothermal atomic absorption spectrometry (for trace element determinations) and inductively coupled plasma optical emission spectrometry (for matrix element determinations). To minimise any other systematic error besides that due to matrix effects, accuracy of the pre-concentration step and contamination levels of the procedure were checked by inductively coupled plasma mass spectrometric measurements. Analytical results obtained by applying the multiple linear regression models were compared with those obtained with other calibration methods, such as external calibration using acid-based standards, external calibration using matrix-matched standards and the analyte addition technique. Empirical models proved to efficiently reduce interferences occurring in the analysis of real samples, allowing an improvement of accuracy better than for other calibration methods.

Biogeochemical cycling of Pb in the coastal marine environment at Terra Nova Bay, Ross Sea

The biogeochemical cycle of lead in the marine coastal environment of Terra Nova Bay has been investigated by determining the lead concentration in a large number of matrices: marine sediments, pack ice, snow, seawater, marine microlayer, aerosol and eight species of marine organisms (the bivalve molluscs Adamussium colbecki and Laternula elliptica, the seastar Odontaster validus, the sea urchin Sterechinus neumayeri, the fish Trematomus bernacchii, the seaweeds Iridaea cordata and Phyllophora antarctica, and the nemertine worm Parborlasia corrugatus). The study of solid speciation of sediment showed that the site is not influenced by human activity and is hence suitable to examine natural processes. The concentration values found in the suspended paniculate matter (SPM) of pack ice core, aerosol, marine microlayer and seawater as well as the particulate morphology, investigated by SEM, seem to support the hypothesis that particulate lead is transferred from the atmosphere to the water column through three different mechanisms: (i) release of SPM from the pack ice during its melting, (ii) input from the continental land through wet deposition, (iii) transport by aerosol and marine microlayer. Concentration data both in the whole organism and in some target organs indicated two suitable biomonitor organisms: the bivalva Laternula elliptica (particularly its digestive gland) and the fish Trematomus bernacchii (particularly its bones).

Antarctic Environmental Specimen Bank-First 5 Years of Experience

Abstract The Project on an Antarctic Environmental Specimen Bank (Banca Campioni Ambientali Antartici—BCAA) began in 1994 in order to collect and classify samples from the Antarctic ecosystem to be used for future studies. The objectives of the project are similar to the general aims of the Environmental Specimen Banks, but they specifically focus on the chemical aspects concerning the research activities of the Italian Project on the “Micropollutants Chemistry” (Sector “Chemical Contamination” of the Italian Antarctic Research Programme—PNRA). During these first years the facilities suitable for storing a significant number of specimens (now over 2,000) at different temperatures (from −30°C to −150°C) and a database system, specifically designed for managing and consulting information concerning both the storage of samples and data on their chemical characterisation, have been developed. In addition, a programme for validating the procedures of Antarctic organisms storage by checking the stability of some chemical parameters both in fresh and freeze-dried specimens has been developed.

Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses

AbstractTo provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP–AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP–MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots. FigureRoots, stems and leaves of different Nicotiana langsdorffii genotypes exposed to abiotic stresses were analysed by ICP-AES and ICP-MS, obtaining information on the distribution of 29 major and trace elements in the samples

The occurrence of lead in the bone tissues of Trematomus bernacchii , Terra Nova Bay, Ross Sea

The occurrence of lead in various bone tissues of Trematomus bernacchii was investigated in order to identify the optimal target tissue and to examine potential relationships between bone lead concentration and fish size and age. Lead concentration values found in vertebrae and jaws (0.44 ± 0.13 and 0.41 ± 0.09 μg g−1 of dry weight tissue, respectively) were significantly higher than those in the other bones examined (otoliths, branchiostegal rays and pectoral girdles), indicating a preferential accumulation of lead in these tissues. Hence, vertebrae and jaws were selected as suitable target organs. The significance of T. bernacchii as a marker of lead bio-availability for the marine environment was tested by comparing data with the ones obtained for the Scorpaena notata, a benthic fish living in the more polluted coasts of the Mediterranean Sea, and by correlating the lead content found in the fish bones with the concentration of bio-available lead in the marine sediments on which the two fishes live. Bio-availability was evaluated by solid speciation and size fractionation techniques. All data clearly indicated that the difference in bone lead content between S. notata and T. bernacchii (0.83 ± 0.17 μg g−1 and 0.42 ± 0.08 μg g−1, significant at the 99.9% confidence level) can be ascribed to the concentration of bio-available lead in their respective environment. Finally, no correlation between the lead accumulation in bone tissues and fish size and age was found for either fish species.

Monitoring of heavy metals and butyltin compounds in coastal waters of Ligurian Sea: Results of a mussel watch project

From December 1994 up to October 1995 a “Mussel Watch Project”; was carried out to assess the quality of water of the Ligurian Sea and to identify the possible sources of heavy metal pollution. Several metals and organotin compounds were measured in mussels (Mytilus galloprovincialis, Lam) transplanted in different months from a marine farm to eight sites of the Ligurian coast. Spatial differences and temporal trends in tissue concentrations of Zn, Cu, Ni, Cr, Fe, Al, V, Cd and Mn were evaluated. Concentrations resulted in the same range as those obtained in a previous Mussel Watch Project carried out in the same area. In general, areas of known pollution display high concentrations of these metals, but also some areas not greatly influenced by human activities showed high concentrations of some metals. Data from this study show little evidence of any overall seasonal pattern except for Cu, Zn and V, concentrations of which were a function not only of sampling site, but also of reproductive cycle. Organotin compounds show differences in terms of both concentration and speciation between the investigated sites.