Angela Maria Stortini

Organic pollutants in sea-surface microlayer and aerosol in the coastal environment of Leghorn—(Tyrrhenian Sea)

Abstract The levels of dissolved and particle-associated n -alkanes, alkylbenzenes, phthalates, PAHs, anionic surfactants and surfactant fluorescent organic matter (SFOM) were measured in sea-surface microlayer (SML) and sub-surface water (SSL) samples collected in the Leghorn marine environment in September and October 1999. Nine stations, located in the Leghorn harbour and at increasing distances from the Port, were sampled three times on the same day. At all the stations, SML concentrations of the selected organic compounds were significantly higher than SSL values and the enrichment factors (EF=SML concentration/SSL concentration) were greater in the particulate phase than in the dissolved phase. SML concentrations varied greatly among the sampling sites, the highest levels ( n -alkanes 3674 μg/l, phthalates 177 μg/l, total PAHs 226 μg/l) being found in the particulate phase in the Leghorn harbour. To improve the knowledge on pollutant exchanges between sea-surface waters and atmosphere, the validity of spray drop adsorption model (SDAM) was verified for SFOM, surface-active agents, such as phthalates, and compounds which can interact with SFOM, such as n -alkanes and PAHs.

Sampling sea surfaces with SESAMO: an autonomous craft for the study of sea-air interactions

This paper presents the system design, sea trials and Antartic exploitation of the SESAMO platform. The SESAMO (sea surface autonomous modular unit) prototype robot was especially designed to collect data and samples for the study of the sea-air interface. At sea, operations showed that a relatively simple robot could satisfactorily work in a natural, outdoor environment, dramatically facilitating the job of the human operator. To achieve high quality sampling of the surface microlayer, however, requires a large amount of time, leading to significant demands on logistics resources, mainly in terms of operating time of the support vessel.

Comparison of PM10 concentrations and metal content in three different sites of the Venice Lagoon： An analysis of possible aerosol sources

The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified.

Chemical characterization of cloud episodes at a ridge site in Tuscan Appennines, Italy

Cloudwater samples were collected from November 1992 to March 1995 in Vallombrosa, a mountain site of the Tuscan Apennines (central Italy). Chemical analyses show that all examined inorganic ions contributed significantly to the total ionic content (TIC). The ratio SO42−/NO4− ranged from 0.92 to 3.46 and was >1 for 86% of samples. There is a wide range in the chemical composition of the cloudwater. The total ionic content ranged from 640 to 7476 μeq l−1 and pH from 3.17 to 6.22. The liquid water content (LWC) ranged from 0.06 to 0.94 g m−3 and electrical conductivity from 47 to 485 μΩ−1. The total ionic content decreases while the liquid water content increases. Also analyzed were soluble trace metals (Fe, Pb, Cu, Mn, Cd, Al), synthetic anionic surfactants and the methanesulphonic acid. Chemical analyses evidenced in some cases a high concentration of organic matter. The meteorological analysis for a few samples of individual passages was carried out for the possibility of establishing a correspondence between meteorological events and chemical composition. The sources (marine, crustal and anthropogenic) of chemical components were deduced.

Non-equilibrium properties of fluid interfaces - Aperiodic diffusion-controlled regime. 1. Theory

Abstract Surface relaxation processes of liquid solutions, under not-far-from-equilibrium conditions, are interpreted from a phenomenological point of view by application of the theory of distributed systems. In the case of diffusion-controlled adsorption, exact analytical expressions describe the transient responses of bulk concentration and dynamic surface tension, consequent to trapezoidal pulses of relative surface area. The mathematical treatment shows that surface responses have a definite physical significance, as they manifest a constitutive property of the system, i.e. the surface dilational modulus.

Organic micropollutants in wet and dry depositions in the Venice Lagoon.

Atmospheric transport is an important route by which pollutants are conveyed from the continents to both coastal and open sea. The role of aerosol deposition in the transport of polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) and polybromodiphenyls ethers (PBDEs) to water and soil systems has been evaluated by measuring their concentrations in wet and dry depositions to the Venice Lagoon. The organic micropollutant flux data indicate that they contribute to the total deposition flux in different ways through wet and dry deposition, showing that the prevalent contribution derives from wet deposition. The fluxes calculated for PBDEs, showed the prevalence of 47, 99, 100 and 183 congeners, both in dry and wet fluxes. With regard to PCBs, the flux of summation operatorPCB for wet deposition is in the same order of magnitude of the diffusive flux at the air-water interface. The PAH fluxes obtained in the present study are similar to those obtained in previous studies on the atmospheric bulk deposition to the Venice Lagoon. The ratios between Phe/Ant and Fl/Py indicate that the pollutants sources are pyrolytic, deriving from combustion fuels.

Analysis of organic compounds in Antarctic snow and their origin

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.

Air-Sea Exchange: Sea Salt and Organic Microcomponents in Antarctic Snow

Abstract A characterization of surface active fluorescent organic matter (SAFOM) in Antarctic snow is carried out. Its Fulvic Acids (FA) nature is confirmed. Its enrichment in the smallest aerosol particles is shown. A tentative explanation of the presence of both natural and man-made organic microcomponents (SAFOM-interacting) is given in terms of marine aerosol transport. Their enrichment ratio appears of the same order as that of SAFOM, and their presence in the atmospheric particulate of marine origin supports the hypothesis on the transport of microcomponents in Antarctica “via marine aerosol”.

Humic marine matter and insoluble materials in Antarctic snow

Abstract The aim of the present work is to show that the insoluble components of marine origin are always present, together with the soluble ones, in both the coarse fraction and in the fine fraction of the marine aerosol and that they make up a non negligible part of the insoluble material in Antarctic snow. The results obtained show that a large proportion of the insoluble matter present in high altitude Antarctic snow consists of marine organic matter involved in the aerosolization process and that the thermolabile fraction (4000C), largely consisting of fulvic acids, increases with increasing altitude. The effect of distance from the sea coast is harder to demonstrate for particulate fulvic acids at least over the short distances investigated herein (150 km) and owing to the complex orography of the sample areas.

Nonequilibrium properties of fluid interfaces: aperiodic diffusion-controlled regime 2. Experiments

Abstract We have investigated the surface dilational properties of a submicellar aqueous solution of n -dodecyldimethyl-phosphine oxide. We compared (a) the steady-state responses of dynamic surface tension, induced by small-amplitude harmonic disturbances of surface equilibrium (at different frequencies), and (b) the transient response induced on the same sample by a single trapezoidal-pulse disturbance. Using the equations for a diffusive model, we determined the fit parameters from the observed response values both in the frequency and in the time domains. The results enabled us to predict satisfactorily the harmonic dynamic behaviour of the surface, from the relaxation data. The prediction-bservation agreement supports the theoretical treatment and, in particular, the assertion that the viscoelastic link, between surface excitation and response, is a constitutive property of a liquid solution. The experiments also show the existence of a linearity range and the repeatability of measurements.