4 research outputs found
Evidence for heavy fuel oil combustion aerosols from chemical analyses at the island of Lampedusa: a possible large role of ships emissions in the Mediterranean
Measurements of aerosol chemical composition made on the island of Lampedusa, south of the Sicily channel, during years 2004–2008, are used to identify the influence of heavy fuel oil (HFO) combustion emissions on aerosol particles in the Central Mediterranean. Aerosol samples influenced by HFO are characterized by elevated Ni and V soluble fraction (about 80% for aerosol from HFO combustion, versus about 40% for crustal particles), high V and Ni to Si ratios, and values of V<sub>sol</sub>>6 ng m<sup>−3</sup>. Evidence of HFO combustion influence is found in 17% of the daily samples. Back trajectories analysis on the selected events show that air masses prevalently come from the Sicily channel region, where an intense ship traffic occurs. This behavior suggests that single fixed sources like refineries are not the main responsible for the elevated V and Ni events, which are probably mainly due to ships emissions. <br><br> V<sub>sol</sub>, Ni<sub>sol</sub>, and non-sea salt SO<sub>4</sub><sup>2&minus;</sup> (nssSO<sub>4</sub><sup>2&minus;</sup>) show a marked seasonal behaviour, with an evident summer maximum. Such a pattern can be explained by several processes: (i) increased photochemical activity in summer, leading to a faster production of secondary aerosols, mainly nssSO<sub>4</sub><sup>2&minus;</sup>, from the oxidation of SO<sub>2</sub> (ii) stronger marine boundary layer (MBL) stability in summer, leading to higher concentration of emitted compounds in the lowest atmospheric layers. A very intense event in spring 2008 was studied in detail, also using size segregated chemical measurements. These data show that elements arising from heavy oil combustion (V, Ni, Al, Fe) are distributed in the sub-micrometric fraction of the aerosol, and the metals are present as free metals, carbonates, oxides hydrates or labile complex with organic ligands, so that they are dissolved in mild condition (HNO<sub>3</sub>, pH1.5). <br><br> Data suggest a characteristic nssSO<sub>4</sub><sup>2&minus;</sup>/V ratio in the range 200–400 for HFO combustion aerosols in summer at Lampedusa. By using the value of 200 a lower limit for the HFO contribution to total sulphates is estimated. HFO combustion emissions account, as a summer average, at least for 1.2 μg m<sup>−3</sup>, representing about 30% of the total nssSO<sub>4</sub><sup>2&minus;</sup>, 3.9% of PM<sub>10</sub>, 8% of PM<sub>2.5</sub>, and 11% of PM<sub>1</sub>. Within the used dataset, sulphate from HFO combustion emissions reached the peak value of 6.1 μg m<sup>−3</sup> on 26 June 2008, when it contributed by 47% to nssSO<sub>4</sub><sup>2&minus;</sup>, and by 15% to PM<sub>10</sub>
Sviluppo di metodi di atomizzazione al plasma per la determinazione di metalli nel particolato atmosferico e in sedimenti marini continentali. Studio delle interazioni uomo – ambiente – clima in aree a diverso grado di antropizzazione
Major and trace (including REEs) element stratigraphy in the first 90 m (around 1 Myr) of ANDRILL AND-1B drillcore.
An integrated system Inductively Coupled Plasma - Sector Field Mass Spectrometry (ICP-SFMS) and Inductively
Coupled Plasma – Atomic Emission Spectrophotometry (ICP – AES) has been applied to quantify 39 major
and trace elements (including Rare Earths Elements -REE) in Antarctic glaciomarine sediments collected in the
framework of ANDRILL. This project aims to study the role of the Antarctic Continent within the global climatic
system, by the recovery and analysis of two deep sediment cores (AND-1B, MIS and AND-2A, SMS), drilled
close to the margin of the Ross Ice Shelf. The main goals of ANDRILL were to obtain a stratigraphic record
that documents key steps in Antarctica’s Cenozoic climatic and glacial history, and in the tectonic evolution of
the Transantarctic Mountains and the West Antarctic rift System. In particular, the study of the geochemical
composition of sediments along the two ANDRILL cores can provide information about the possible source of
terrigenous material deposited over the drilling site (Harwood et al., 2006).
Preliminary results with a spatial resolution of about 1 m for the geochemical composition of the interval 24.66-
85.24 m of depth of marine sediments from AND-1B core covering about the last 1 Ma, are here shown. The
concentration ratio of each measured element with respect to Al concentration, used as terrigenous reference, was
calculated in order to remove the possible effect on elemental concentrations of differences in average sediment
grain-size along the core and possible dilution effects and point out specified metal enrichments. The presented
data and depth profiles (e.g. Fe/Al, Mn/Al, Co/Al, Cr/Al, Eu/Al and Europium anomaly) relative to sediments
deposited during the last Ma at the MIS site, show an evident discontinuity from samples collected above and
below 58.4 m of depth, corresponding to about 0.45 Ma BP, following the latest AND-1B dating model (85.24 m
of depth corresponding to about 0.988 Ma; the chronological datum of the sediments is developed from 40Ar/39Ar
ages volcanic deposits, Naish et al. 2009). This difference of geochemical composition suggests different rock
sources for the material deposited before and after about 0.45 Ma BP. In particular the geochemical composition
of the upper sediments is similar to the one of McMurdo Volcanic Group (MVG) whereas the lower sediments
are close to the compositions of samples collected in the Transantarctic Mountain (TAM). Such a different
composition could be linked to the climatic discontinuity known as Mid-Brunhes Event (MBE), dated 430 Kyr BP,
which marks the boundary between two different global climatic conditions, with the youngest part characterized
by a larger temperature gap between short and warm interglacials and long and cold glacials, with respect to the
oldest part
The 'Great Southern Reef': Social, ecological and economic value of Australia's neglected kelp forests
Kelp forests define >8000km of temperate coastline across southern Australia, where ~70% of Australians live, work and recreate. Despite this, public and political awareness of the scale and significance of this marine ecosystem is low, and research investment miniscule (<10%), relative to comparable ecosystems. The absence of an identity for Australia's temperate reefs as an entity has probably contributed to the current lack of appreciation of this system, which is at odds with its profound ecological, social and economic importance. We define the 'Great Southern Reef' (GSR) as Australia's spatially connected temperate reef system. The GSR covers ~71000km2 and represents a global biodiversity hotspot across at least nine phyla. GSR-related fishing and tourism generates at least AU$10 billion year-1, and in this context the GSR is a significant natural asset for Australia and globally. Maintaining the health and ecological functioning of the GSR is critical to the continued sustainability of human livelihoods and wellbeing derived from it. By recognising the GSR as an entity we seek to boost awareness, and take steps towards negotiating the difficult challenges the GSR faces in a future of unprecedented coastal population growth and global change