1,721,098 research outputs found
Modelling of the Phyisico-Chemical Properties of HCFCs whith WHIM Molecular Descriptors: Rate Constant of the Reaction of OH Radical with Hydrohaloalkanes
No full textFT-IR Spectroscopy and chemometrics as a useful approach for determining chemical-physical properties of gasoline, by minimizing analytical times and sample handling
No full textProcesses affecting the distribution of PCBs in the Southern Ocean
No full textPolychlorinated biphenyls (PCBs) are a broad class of globally distributed persistent pollutants that differ in their degree of chlorination and, thereby, in their volatility and are subject to long-range atmospheric transport (LRAT). Although their industrial production was discontinued in the early nineties, some PCB congeners are still released into the environment as unintentional by-products of dye manufacturing and other chemical productions. Among them, 3,3’-dichlorobiphenyl (PCB-11) has been detected at concentrations often higher than those of the other technical congeners (i.e. legacy Aroclor PCBs) in almost all the environmental compartments, even in polar areas (Choi et al., 2008).
It is known that the atmosphere plays a key role in transport and distribution of persistent organic pollutants (POPs) towards polar areas, through successive phases of volatilization and deposition that occur at the air/water interface. The low temperatures of the polar areas promote this partition between the atmosphere and the seawater surface via the cold trapping mechanism (Wania and MacKay, 1996). However, this process is reversible, so the partition of POPs moves in one direction or in the opposite one depending on the volatility of the molecules involved, their relative concentration in air and water, and changes in temperature (Galbán-Malagón et al., 2013).
As the surface water temperature decreases, lighter congeners, more prone to volatilization, tend instead to settle in the water surface layers. Indeed, in the Southern Ocean, where the temperature of surface water is reduced to values close to that of the air, a particularly high concentration of PCB-11 compared to that of other less volatile PCB congeners have been reported (Choi et al., 2008; Pizzini et al., 2017). Instead, PCBs with a higher degree of chlorination are less prone to volatilization in temperate areas and, consequently, they would be preferentially transferred to the Southern Ocean through Modified Circumpolar Deep waters (Fuoco et al., 2009) rather than via LRAT. Against this background, it can be assumed that more processes are involved in the transport of PCBs towards the Southern Ocean, depending on the characteristics of the investigated molecules and, primarily, their volatility.
In this work, the results of analyses of water samples collected along a transect from the Southern Pacific Ocean to the Ross Sea will be presented. Preliminary outcomes confirmed the hypothesis that more volatile PCBs reach the Southern Ocean preferentially through a cold condensation process, differently from heavier ones. Di- and Tri-chlorinated PCBs reached particularly high concentrations in water surface layers where there is a sharp decrease in temperature, in the Antarctic convergence zone, while this effect is much more limited for the less volatile investigated congeners.
Choi, S.-D., Baek, S.-Y., Chang, Y.-S., Wania, F., Ikonomou, M.G., Yoon, Y.-J., Park, B.-K., Hong, S., 2008. Passive Air Sampling of Polychlorinated Biphenyls and Organochlorine Pesticides at the Korean Arctic and Antarctic Research Stations: Implications for Long-Range Transport and Local Pollution. Environmental Science & Technology 42, 7125-7131. https://doi.org/10.1021/es801004p.
Fuoco, R., Giannarelli, S., Wei, Y., Ceccarini, A., Abete, C., Francesconi, S., Termine, M., 2009. Persistent organic pollutants (POPs) at Ross Sea (Antarctica). Microchemical Journal 92(1), 44-48. https://doi.org/10.1016/j.microc.2008.11.004.
Galbán-Malagón, C. J., Del Vento, S., Cabrerizo, A., Dachs, J., 2013. Factors affecting the atmospheric occurrence and deposition of polychlorinated biphenyls in the Southern Ocean. Atmospheric Chemistry and Physics 13, 12029-12041. https://doi.org/10.5194/acp-13-12029-2013.
Pizzini, S., Sbicego, C., Corami, F., Grotti, M., Magi, E., Bonato, T., Cozzi, G., Barbante, C., Piazza, R., 2017. 3,3’-dichlorobiphenyl (non-Aroclor PCB-11) as a marker of non-legacy PCB contamination in marine species: comparison between Antarctic and Mediterranean bivalves. Chemosphere 175, 28-35. https://doi.org/10.1016/j.chemosphere.2017.02.023.
Wania, F., MacKay, D., 1996. Tracking the Distribution of Persistent Organic Pollutants. Environmental Science & Technology 30(9), 390A-396A. https://doi.org/10.1021/es962399q
Simultaneous determination of halogenated contaminants and polycyclic aromatic hydrocarbons: a multi-analyte method applied to filter-feeding edible organisms
No full textThis study develops and validates a novel analytical approach for the simultaneous determination of 127 polychlorinated biphenyls (PCBs), together with 6 polychlorinated naphthalenes (PCNs) and 16 polycyclic aromatic hydrocarbons (PAHs). PCBs, PCNs, and PAHs were subjected to a unique pretreatment protocol and were simultaneously determined in a single chromatographic run, using GC-MS, in environmental marine samples of mussels and clams. The results of the validation experiments, which were performed on the standard reference materials (NIST SRM 1974C – slurried matrix and NIST SRM 2977 – freeze-dried matrix), were in accordance with the certified and the reference values. The repeatability of the method for all target compounds, expressed as mean relative standard deviations, ranged from 2.5 to 5.1 % for PCBs, from 3.9 to 5.5 % for PCNs, and from 8.6 to 17.9 % for PAHs; the first value of each pair refers to the freeze-dried matrix and the second to the fresh one, for each of the classes of compounds examined. The quantification limits were in the range of 0.2–6 pg for PCBs, 0.4–8 pg for PCNs, and 0.2–15 pg for PAHs (on column). The method recoveries yielded good results (62 ± 19 % for the freeze-dried matrix and 60 ± 14 % for the fresh one) and were not significantly reduced by adopting a single analytical protocol compared with the use of different group-specific analytical methods. No serious interferences were encountered and good selectivity was achieved. These results show that this method allows one to increase the laboratory sample throughput while requiring a small amount of tissue and saving time
First evidence of the suitability of hair for assessing wildlife exposure to anticoagulant rodenticides (ARs)
No full textAnticoagulant rodenticides (ARs) are potent pesticides acting as vitamin K epoxide reductase inhibitors causing haemorrhaging or external bleeding from orifices and/or skin lesions in intoxicated rodents. However, their non-selective mode of action makes them particularly harmful for non-target wildlife, which may be exposed to ARs via ingestion of AR-containing baits (primary exposure), feeding on AR-intoxicated rodents and carrions (secondary exposure), consuming AR-contaminated necrophagous species (tertiary exposure), and exposure to surface waters receiving baited sewer systems and ARs from outdoor-placed traps after heavy rain events. In the present study, we assessed the suitability of hairs as a non-invasive matrix for monitoring the possible exposure of mammals to ARs with a focus on the first-generation anticoagulant rodenticides (FGARs) warfarin, coumatetralyl, and chlorophacinone and the second-generation anticoagulant rodenticides (SGARs) brodifacoum, bromadiolone, difenacoum, flocoumafen, and difethialone. The Red fox (n = 24) was selected as the species representing the potentially exposed non-target wildlife in a littoral area of Northern Italy along the Adriatic coast (Cavallino-Treporti municipality). Half (n = 12) of the analysed hair samples were positive for at least one of the targeted ARs, with a higher prevalence of SGARs (n = 11; 46%) compared to FGARs (n = 1; 4%). The most frequently quantified ARs were brodifacoum (25%), difethialone (13%), and flocoumafen (13%), with concentrations ranging from 0.08 ng g−1 (difethialone) to 0.96 ng g−1 (brodifacoum). These data documented that a relevant part of the Red foxes living in the study area were exposed to ARs and, most importantly, provided the first evidence that hair residues can be used as a non-invasive matrix for assessing the possible exposure of mammals to ARs
Simultaneous determination of halogenated contaminants (PCBs and PCNs) and polycyclic aromatic hydrocarbons (PAHs) in biota integrated into a single method
Full text linkIn this study, a novel analytical approach for the simultaneous determination of 127 polychlorinated biphenyls (PCBs), together with 6 polychlorinated naphthalenes (PCNs) and 16 polycyclic aromatic hydrocarbons (PAHs) was developed and validated.
The number of environmental contaminants which undergo legislation continues to increase, fostering the development and validation of sensitive, selective, fast and inexpensive analytical methods.
The determination of such analytes often requires long and expensive procedures for each class of compounds. This does not allow the rapid and fast analysis of large quantity of samples for food safety screening purposes.
The aim of this study was to develop a method for the simultaneous determination of PCBs, PCNs and PAHs in biological samples (bivalves tissues) from extraction to instrumental analysis.
The method uses pressurized liquid extraction (PLE), gel permeation chromatography (GPC) for lipid fraction removal, automatic preparative liquid chromatography for the clean-up and a single run in HRGC-LRMS.
We integrate analyses of these three groups of POPs into a single analytical protocol from sampling to injection. Not only does this method a lower amount of sample and less time, but it also allows one to increase the sample throughput.
The use of one single pre-analytical method allows one to simplify the procedures and save time, while the single run in GC-MS enables the collection of more data simultaneously and in less time (about 75 minutes for 149 analytes) compared to separate analyses
Determination by HRGC/HRMS of PBDE levels in edible Mediterranean bivalves collected from north-western Adriatic coasts
No full textThis study provides information on edible marine species sampled from the north-western coast of the Adriatic Sea. Polybrominated diphenyl ethers (PBDEs) were detected in bivalves of two different species (Mytilus galloprovincialis and Ruditapes philippinarum). The samples were treated by Pressurized Liquid Extraction (PLE) and analyzed by High-Resolution Gas Chromatography coupled with High-Resolution Mass Spectrometry (HRGC/HRMS).
There are only a few studies about PBDE levels in edible bivalves from the Italian coast, and this is the first time that bivalve species from the north-western Adriatic area are used for screening PBDEs. The total concentrations ranged from 0.003 ng g-1 wet weight (ww) to 6.66 ng g-1, with strong variations within the same sampling site. No significant differences between species were found. Moreover, the results showed that it is important to determine BDE-209, which is often neglected.
The concentrations of PBDEs reported here are relatively higher than those reported for the Mediterranean area. Considering the potentially toxic effects of PBDEs and the lack of specific legislation, this study emphasizes the need to further investigate these compounds and to establish maximum levels in foodstuff
Brominated Flame Retardants in edible bivalves: food control and lack of specific legislation
Full text linkPolybrominated diphenyl ethers (PBDEs) are among the most important classes of additive brominated flame retardants (BFR). They have been identified in every compartment of aquatic ecosystems, from abiotic to biotic matrices, and in industrialized areas as well as in remote ones. PBDEs are persistent, highly bioaccumulative and can move up to high trophic levels through biomagnifications [1].
Due to the growing concern about the potential health risks of PBDEs, their characterization in biological organisms that are widely and frequently consumed as food is paramount. Furthermore, at present there is no local or international regulatory limit for PBDEs in food.
We investigated the spatial distribution and levels of PBDEs in two bivalve species (Mytilus galloprovincialis and Ruditapes philippinarum) sampled from the north-western coast of the Adriatic Sea, that are widely used in the regional cuisine. Analyses were carried out using analytical protocols already developed in the laboratory [2] and were performed by HRGC/HRMS for the simultaneous determination of 14 PBDE congeners in biota tissues. Quantifications were carried out by isotope dilution.
The total concentrations ranged from 0.003 ng g-1 wet weight to 6.66 ng g-1, with strong variations within the same sampling site. No significant differences between species were found. As for decabrominated diphenyl ether, in literature the determination of the BDE-209 is often neglected. However, the results of this study show that Deca-BDE is one of the most abundant congeners. However high, the levels of PBDEs in the samples collected near an industrial area subject to a fishing ban are lower than the values of four edible samples gathered in aquaculture farms and intended for human consumption. The concentrations of ΣPBDEs detected in this study are relatively higher than those reported for the Mediterranean area.
Considering the potentially toxic effects of PBDEs and the lack of specific legislation, this study emphasizes the need to further investigate these compounds and to establish maximum levels in foodstuff.
This work was funded by the Italian Ministry of Education, Universities and Research (MIUR) through the project PRIN (Prot. 2010AXENJ8).
[1] C.A. de Wit, Chemosphere 46 (2002) 583-624.
[2] S. Pizzini et al., Microchemical Journal 121 (2015) 184-191
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