1,720,965 research outputs found
Characterisation of proteinaceous binders and drying oils in wall painting samples by gas chromatography-mass spectrometry
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Innovative stabilization-solidification processes of fly ash from an incinerator plant of urban solid waste
No full textFly ash samples from an incineration plant of urban solid waste (USW) were submitted to a stabilization/solidification process based on encapsulation with a polyester resin. With this process, a very limited increase of about 25% in weight and a compressive strength as high as 1200 kg/cm(2) can be obtained. The efficiency of the process to stabilize/solidify the residues and to reduce the pollutant release was evaluated by performing both mechanical and leaching tests following the IRSA-CNR standard method. The leaching test was based on treating the sample with an acetic acid solution adjusted to pH 5.2 for 24 h under magnetic stirring. Toxic metals (Pb, Cd, and Cu) and organic pollutants (PAHs, PCBs, and OCPs) were determined in raw fly ash samples and in the leaching solutions of treated samples. Raw residues showed higher concentrations of trace metals than the regulatory limits, whereas the stabilized/solidified residues showed a concentration of all the pollutants lower than the regulatory limits and a compressive strength much higher than the suggested minimum value. Finally, a critical comparison with conventional stabilization/solidification processes based on the use of Portland cement highlighted that the polyester resin-based process performed much better in terms of the release of both organic and inorganic pollutants, thus substantially lowering the environmental impact of these residues
Characterisation of organic residues in ointment jars of the roman age from Oplontis and Pompei
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A snow/firn four-century record of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) at Talos Dome (Antarctica).
No full textA four-century record of fourteen polycyclic aromatic hydrocarbons (PAHs) and seven polychlorobiphenyls (PCBs) was obtained from two snow/firn cores gathered at Talos Dome (Antarctica) in order to assess the contribution of human activities to global environmental pollution. The total concentrations of ΣPAH14 and ΣPCB7 were 0.7ng/l and 0.06ng/l in the deepest firn sample analyzed, and 3.4ng/l and 0.22ng/l in surface snow samples deposited over the last few years, respectively. Our data highlighted the presence of PAH maxima in the concentration depth profile, which correlated with non-sea salt sulphate maxima associated with the major known volcanic eruptions in the period 1600–1930. PAHs showed the highest concentration in the core (4.6ng/l) at a depth of about 27,8m (14,8m water equivalent), here named the “Tambora PAH excess”, in relation to the Tambora eruption (1815A.D.), the largest in recorded history. Surprisingly the data also revealed the presence of synchronous PCB maxima, with a well defined peak (0.14ng/l) at a depth of 27,8m. Between 1930 and 2002, PAHs showed an overall 50% increase, with a slope of about 0.013ngl-1 year-1. This can be predominantly attributed to the emission of incomplete combustion processes of organic matter related to anthropogenic activities. PCBs show a much higher increase (+200%) with a slope of 0.0034ngl-1 year-1 in a very limited period (1930–1980) which is almost totally due to the massive industrial production and use of PCBs, here named “industrial PCB excess”. The slight tendency of PCBs to a constant level from 1980 to 2002 might be attributed to the reduction in the industrial production of PCBs and the restricted use only in totally enclosed systems which started in many countries in the late 1970s
Paleo-environmental record of polycyclic aromatic hydrocarbons and polychlorobiphenyls at the peripheral site GV7 in Victoria Land (East Antarctica)
No full textIn this paper we investigated the presence of Polycyclic Aromatic Hydrocarbons and Polychlorobiphenyls in a 50-m deep snow/firn core collected at the peripheral site GV7 in East Antarctica during the 2013–2014 XXIX Italian expedition. The concentration depth profile was obtained on the basis of the total concentration of fourteen PAHs and seven PCBs individually determined by gas chromatography triple quadrupole mass spectrometry. Both classes of pollutants showed synchronized concentration vs time profile throughout the whole period of time covered by the snow/firn core (1892–2012). A correlation between major explosive volcanic eruptions and the concentration maxima of the pollutants was found. PAH maximum (9 ng/L) was about twice the background level (5 ng/L). PCBs showed a similar but more limited trend with barely visible volcanic maxima. This concurrence highlights the contribution of the major explosive volcanic events to the global contamination level for PAHs, as expected, but also for PCBs whose industrial production and use began in 1930. Excluding the maximum values, PAHs and PCBs showed an increase in the period 1956–1986: PCBs from about 0.05 to 0.21 ng/l (400% increase), and PAHs from about 3.5 to 7.8 ng/l (100% increase). Finally, in the last decade (2000–2010) the trend of these pollutants was different: (i) PCBs constantly decrease (from 0.15 ng/L to 0.10 ng/L), thanks to the implemented restriction on their production and on their use only in closed systems in many countries; (ii) PAHs remains practically constant around 6.5 ng/L
Polychlorobiphenyls and polycyclic aromatic hydrocarbons in the sea-surface micro-layer and the water column at Gerlache Inlet, Antarctica
No full textThe enrichment of PCBs (polychlorobiphenyls) and PAHs (polycyclic aromatic hydrocarbons) in the sea-surface micro-layer and depth profile of these pollutants in the water column were investigated at Gerlache Inlet, Terra Nova Bay, Antarctica. Depth profile samplings were repeated three times during the Antarctic summer (from November to February). PCBs and PAHs showed a concentration range in the water column of 30–120 pg l−1 and 150–400 pg l−1, respectively, and these values were very much dependent on the suspended matter content. A nearly two-fold decrease in the pollutant concentration was also observed in the depth profile obtained in February, i.e. late summer, which might be correlated both with the high content of suspended matter and the reduction of the pollutant input. Moreover, isomer ratios of PAHs, such as LMW/HMW and PHE/ANT, highlight that the main PAH source might be petrogenic in nature, whereas the pyrolytic source seems to be less important. Sea surface micro-layer (SML) and sub-surface sea water (SSW) samples were simultaneously collected in the same site by a remote controlled rotating drum-based sampling system, a prototype named MUMS (Multi-User Micro-layer Sampler). Sea surface micro-layer samples showed a total content of PCBs and PAHs in the range 400–450 pg l−1 and 2000–3000 pg l−1, respectively, whereas the mean content of the sub-surface sea water samples was 48 pg l−1 and 325 pg l−1, respectively. The mean enrichment factors of PCBs and PAHs in sea-surface micro-layer were about 10 and 7, respectively. The surface excess concentrations of PCBs and PAHs were about 35 000 and 200 000, respectively. A fairly good correlation was observed between the concentration of pollutants and water solubility. Based on the assumption that POPs are confined in a very thin top layer of the SML about 0.01–0.001 μm thick, namely the sea-surface nano-layer, and also on an estimated thickness of the sampled sea-surface layer of about 100 μm, an enrichment factor of 105–106 for the sea-surface nano-layer was calculated. Such a very high concentration increase was related to the two-fold increase of PAH concentration observed in the underlying 20 cm of the water column in late summer
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