Serena Massolo

Geochemical fractionation of trace elements in sediments of Hugli River (Ganges) and Sundarban wetland (West Bengal, India)

A sequential extraction procedure was carried out to determinate the concentrations of 11 elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in different geochemical phases of sediments collected along the Hugli (Ganges) River Estuary and in the Sundarban mangrove wetland, eastern coastal part of India. The chemical speciation of elements was determined using the three-step sequential extraction procedure described by the European Community Bureau of Reference. Total metal concentration was determined using a microwave-assisted acid digestion procedure. Metal concentrations were near the background level except for As for which a moderate pollution can be hypothesized. The mobility order of the metals was: Cd > Mn > Cu > Zn > As > Co > Pb > Ni > Fe > Cr > Al. The highest percentage of Cd (>60%) was found in the most labile phase. Residual fraction was prevailing for Fe, Cr and Al, while Pb was mainly associated with the reducible fraction. Data were compared with Sediment Quality Guidelines to estimate the relationship between element concentrations and adverse biological effects on benthic community, finding the possibility of some toxic effects due to the presence of As in the entire studied area and Cd, only in Calcutta.

Heavy Metals Distribution in Suspended Particulate Matter and Sediment Collected from Vlora Bay (Albania): A Methodological Approach for Metal Pollution Evaluation

Abstract Heavy metals (Al, Fe, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn) content was evaluated in suspended particulate matter and sediment samples collected from Vlora Bay (Albania) in the framework of Centro Internazionale di Scienze del Mare (CISM) Project activities. The trend of the metals (in general, overlapping that showed by the suspended particulate matter distribution), together with the linear correlation values found between metals, suggested the pivotal role of the Vjosa River and of the inner circulation scheme of Vlora Bay on their distribution. The geoaccumulation index, Igeo, was calculated as a criterion to assess if a metal concentration found in the sediment represents contamination level or can be considered as background level. The results show that metals concentrations in sediments can be considered near the background levels found in the Mediterranean Sea, even if some accumulation was found in several stations. The data were compared to Sediment Quality Guidelines considering the ERL (effects range low) and ERM (effects range medium) values, to evaluate the potential effects of sediment-associated metals on aquatic organisms. The Ni value for all samples was above the ERM value, while Cr and As values were in between ERL and ERM. Metal speciation was also evaluated in some sediment samples. Generally, the metals found were associated with the refractory phases, which constitute up to 80% of the total concentration. Moreover, the sampling strategies and the adopted analytical methods were compared to those recommended by national and international regulations.

Heavy metals in albanian coastal sediments

Heavy metals (Fe, Mn, Cr, Ni, Cu, Cd, Pb, Sn) concentration has been determined on 39 coastal sediment samples collected in Albania. The relationship between the heavy metals content and the grain size has been considered. All metals, except Cu and Cd, resulted accumulated in the finest fraction, which constituted up to 95% of most of the considered sediments. A good correlation has been found for Ni, Cr, Fe, Zn, Cu in the entire area, indicating a common origin for these metals in the analyzed sediments. Concentration values fall in the range reported for Dinaric chain derived sediments, revealing, generally, a natural origin of the metal contents. Though in some selected areas such as the Drin and the Skumbin Bay, an antropogenic input of Cr, Fe, Ni and Cu can be observed, as the result of discharging of mines and smelter activities.

Speciation of heavy metals in Albanian coastal sediments

This article presents results on heavy metal (Fe, Mn, Cr, Ni, Cu, Cd, Pb and Zn) speciation in the coastal sediments of Albania. Sediment samples were collected within the framework of the activities of the Interreg Italia–Albania Project, carried out in the Southern Adriatic Sea in 2000–01. This study shows that Albanian coastal sediments are highly influenced by river input, as the decreasing concentrations from coast to offshore confirm. Pb represents an exception of the general trend; meteoric inputs are prevalent for this metal. Ni, Cr, Fe, Zn and Cu correlate significantly and positively in the entire area, indicating a common origin for these metals in the analyzed sediments. All metals result mostly associated to the most refractory phases, which constitute up to 80% of the total concentration. Nevertheless a recent input of Cr, Ni, Cu and Mn can be observed, as the result of mining and industrial activities, in some selected areas, such as the Drin Bay and Durres. Their high concentration in the bioavailable phase can determine toxic effect upon biota.

Spatial and seasonal variability of dissolved oxygen and nutrients in the Southern Adriatic coastal waters

The main objective of this paper is to present vertical and horizontal patterns of dissolved oxygen and nutrients found during four seasonal surveys (March, June, September and December 2000) in the Southern Adriatic Sea coastal waters. The multivariate technique Principal Component Analysis has been applied to our dataset considering the following parameters: seawater temperature, salinity, dissolved oxygen and nutrients (nitrate, nitrite, phosphate, silicate). The resulting plot shows in a self-explanatory way that a seasonal trend was not observable in the investigated period and that no significant differences occur between the stations sampled in the Taranto Gulf and those along the Adriatic coast. Water column stratification persists in all seasons, except in spring, in the shallowest stations. The surface layer is characterized by a low nutrient content. The influence of the Northern Adriatic Surface Water in the Southern Adriatic sub-basin seems to be very low and can be traced by nitrate and silicate only in spring and winter. Regarding deep waters, nitrate distribution shows an increasing gradient moving from the coast to the open sea, having the lowest concentration in the shelf area and the highest in the most offshore stations of the Otranto Strait. In the Otranto Strait area the vertical distributions of physical and chemical parameters show, at middle depths, the inflow of Levantine Intermediate Water, traced by both the maximum of salinity, nitrate and phosphate and the minimum of oxygen. The LIW signal is lost moving northward. The outflow of Adriatic Dense Water is less evident, being traced only in spring by an oxygen increase at the bottom layer in the shelf area. The N:P ratio is highly variable but in the range already observed in the Southern Adriatic, suggesting a P-limitation, which can both contribute to the low primary productivity of the area and support the N:P ratio anomaly of the Eastern Mediterranean.

Simultaneous determination of CFC-11, CFC-12 and CFC-113 in seawater samples using a purge and trap gas-chromatographic system

We have optimized the analytical parameters of a homemade instrument for the simultaneous measurement of the chlorofluorocarbons CCl(2)F(2) (CFC-12), CCl(3)F (CFC-11) and C(2)Cl(3)F(3) (CFC-113) in seawater. Seawater samples are flame sealed into 60 ml glass ampoules avoiding any contact with the atmosphere and stored in cold, dark condition until analysis. In the laboratory, after cracking the ampoule in an enclosed chamber filled with ultra-pure nitrogen, the seawater sample is transferred to a stripping chamber, where ultra-pure nitrogen is used to purge the dissolved CFCs from the seawater. The extracted gases are then cryogenically trapped, subsequently the trap is isolated and heated and the CFCs are transferred by a carrier gas stream into a precolumn and then are separated on a gaschromatographic packed column. To separate adequately CFC-12 from N(2)O, during the early part of the chromatographic run, the gas stream passes through a molecular sieve, which is then isolated and backflushed. The CFCs are detected on an electron capture detector ((63)Ni ECD). After a careful choice of the experimental conditions, the performances of the system were evaluated. The detection limits for seawater samples are: 0.0081 pmol kg(-1) for CFC-12, 0.0073 pmol kg(-1) for CFC-11 and 0.0043 pmol kg(-1) for CFC-113. The reproducibility of replicate samples lies within 5% for the three CFCs. The system has been successfully employed for CFC measurements in seawater samples collected in the Ross Sea (Antarctica) in the framework of the Italian Antarctic research project.

Variability of nutrient and thermal structure in surface waters between New Zealand and Antarctica, October 2004-January 2005

We describe the upper ocean thermal structure and surface nutrient concentrations between New Zealand and Antarctica along five transects that cross the Subantarctic Front, the Polar Front (PF) and the southern Antarctic Circumpolar Current (ACC) front. The surface water thermal structure is coupled with variations in surface nutrient concentrations, making water masses identifiable by both temperature and nutrient ranges. In particular, a strong latitudinal gradient in orthosilicate concentration is centred at the PF. On the earlier sections that extend south-west from the Campbell Plateau, orthosilicate increases sharply southward from 10–15 to 50–55 µmol l−1 between 58° S and 60° S, while surface temperature drops from 7°C to 2°C. Nitrate increases more regularly toward the south, with concentrations ranging from 10–12 µmol l−1 at 54° S to 25–30 µmol l−1 at 66° S. The same features are observed during the later transects between New Zealand and the Ross Sea, but the sharp silica and surface temperature gradients are shifted between 60° S and 64° S. Both temporal and spatial factors may influence the observed variability. The January transect suggests an uptake of silica, orthophosphate and nitrate between 63° S and 70° S over the intervening month, with an average depletion near 37%, 44% and 29%, respectively. An N/P (nitrite + nitrate/orthophosphate) apparent drawdown ratio of 8.8±4.1 and an Si/N (silicic acid/nitrite + nitrate) apparent drawdown ratio >1 suggest this depletion results from a seasonal diatom bloom. A southward movement of the oceanic fronts between New Zealand and the Ross Sea relative to prior measurements is consistent with reports of recent warming and changes in the ACC.

Chlorofluorocarbon distribution in the ross sea water masses

Chlorofluorocarbon (CFC11, CFC12 and CFC113) data, collected during the 2000–2001 austral summer, within the framework of the activities of the Climatic Long-Term Interactions for the Mass-Balance in Antarctica (CLIMA) Project of the Italian National Program for Antarctic Research (PNRA) in the Ross Sea, are discussed in the context of hydrographic observations. These data provide an overview of CFC distribution in some of the characteristic water masses found in the Ross Sea. The highest values of CFCs are found in the Antarctic Surface Water (AASW), because of the exchange with the atmosphere, while the lowest concentrations and the highest temperatures define the presence of Circumpolar Deep Water (CDW) in the cast of the analyzed samples. High Salinity Shelf Water (HSSW) can be identified by the highest salinity and by the relatively high content of CFCs. Moreover, the CFCs are useful tracers to study the mixing and overflow processes near the shelf break. In particular, chlorofluorocarbons trace the intrusion onto the shelf of Modified Circumpolar Deep Water (MCDW) off Cape Adare. The relative age of this water mass derived from CFCs ratios indicates that ventilation occurred between 1973 and 1979. The thermohaline structures and CFC distribution reveal at the shelf break the presence of HSSW already mixed with MCDW. Consequently, the density value of the bottom layer is not high enough to produce a strong overflow along the shelf break, causing a less intense ventilation of the deep oceans.

Circulation and Lagrangian Dispersal in the Gulf of Vlora (Albania)

Abstract Hydrodynamic and pollutant transport models are useful tools for evaluating remediation options for polluted water bodies. In this work, a Lagrangian-partide approach is used to simulate the three-dimensional pollutants transport in the Gulf of Vlora (Albania) coming from the fresh water outflow from the Vjosa River located in the northern sector of the gulf. Results indicate that the sedimentation processes are strongly dependent on the local meteorology, which is able to modify considerably the circulation of the gulf. Numerical simulations were used to estimate the water circulation and the fate of pollutants in different meteo-oceanographic scenarios identified by the analysis of the oceanographic data collected during two oceanographic cruises carried on during the Centro Internazionale di Scienze del Mare (CISM) project. Suspended sediments are simulated by a large number of Lagrangian elements, the trajectories of which are drawn on the basis of the sea current, settling velocity, and dispersion phenomena. The model was calibrated on the basis of biogeochemical experimental data consisting of concentrations of metals measured in water and in bottom samples, collected during the CISM project performed in the framework of the Interreg III Italia-Albania program. Results of the simulations show that the pollutants coming from the river tend to spread rapidly and undergo rapid dilution for southern and eastern wind regimes. Under northern and western winds a variable percentage of the fine-grained part of sediments discharged by the river penetrates and settles inside the gulf, in accordance with the experimental data.