1. Yearlong measurements of monoterpenes and isoprene in a Mediterranean city (Athens) : natural vs anthropogenic originAnastasia Panopoulou, Eleni Liakakou, Stéphane Sauvage, Valérie Gros, Nadine Locoge, Iasonas Stavroulas, Bernard Bonsang, Evangelos Gerasopoulos, Nikolaos Mihalopoulos, 2020, izvirni znanstveni članek Opis: Monoterpenes and isoprene are important constituents of the volatile organic compounds (VOCs) due to their high reactivity and participation in ozone and secondary aerosol formation. The current work focuses on the results of a 13-month intensive campaign of high resolution time-resolved measurements of these compounds, at an urban background site in Athens, Greece. On an annual basis, monoterpenes (α-pinene and limonene) surpass the isoprene levels presenting mean values of 0.70 ± 0.83 μg m−3, 0.33 ± 0.78 μg m−3 and 0.19 ± 0.36 μg m−3, respectively. The large standard deviation highlights the significant diurnal and day-to-day variability. Isoprene presents a typical seasonal cycle, with a photochemically induced summer-time maximum. Enhanced noon levels are observed during summer, whereas a morning peak in the autumn and winter profiles occurs, despite the generally low levels encountered during these seasons. The monoterpenes deviate from the expected biogenic pattern, presenting higher mean levels during the cold period and a night-to-early morning enhancement strongly related to local anthropogenic tracers such as BC, CO, NO or toluene, as well as increased levels under wind speeds lower than 3 m s−1. Estimations of the anthropogenic and biogenic fractions based on the enhancement ratios of α-pinene versus a variety of anthropogenic tracers, demonstrate a clear dominance of the anthropogenic sources in all studied seasons. Simultaneously, the biogenic fraction increased during summer relative to winter by more than 10 times. Both α-pinene and limonene significantly contribute to locally formed secondary organic aerosol (SOA), determined by means of an ACSM, accounting for at least 22% and 13% of their levels in summer and winter respectively. Additionally, monoterpenes and isoprene contribute 6% to the observed oxidants levels (O3 + NOx) during summer.
Ključne besede: volatile organic compounds, biogenic compounds, monoterpenes, isoprene, Athens
Objavljeno v RUNG: 10.05.2024; Ogledov: 141; Prenosov: 2
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2. Impact of high or low levels of phosphorus and high sodium in soils on productivity and stress tolerance of Arundo donax plantsClaudia Cocozza, Federico Brilli, Laura Miozzi, Sara Pignattelli, Silvia Rotunno, Cecilia Brunetti, Cristiana Giordano, Susanna Pollastri, Mauro Centritto, Gian Paolo Accotto, Roberto Tognetti, Francesco Loreto, 2019, izvirni znanstveni članek Opis: The potential of Arundo donax to grow in degraded soils, characterized by excess of salinity (Na+), and phosphorus
deficiency (-P) or excess (+P) also coupled with salinity (+NaP), was investigated by combining in vivo
plant phenotyping, quantification of metabolites and ultrastructural imaging of leaves with a transcriptome-wide
screening. Photosynthesis and growth were impaired by+Na, -P and+NaP. While+Na caused stomatal
closure, enhanced biosynthesis of carotenoids, sucrose and isoprene and impaired anatomy of cell walls, +P
negatively affected starch production and isoprene emission, and damaged chloroplasts. Finally, +NaP largely
inhibited photosynthesis due to stomatal limitations, increased sugar content, induced/repressed a number of
genes 10 time higher with respect to+P and+Na, and caused appearance of numerous and large plastoglobules
and starch granules in chloroplasts. Our results show that A. donax is sensitive to unbalances of soil ion
content, despite activation of defensive mechanisms that enhance plant resilience, growth and biomass production
of A. donax under these conditions.
Ključne besede: Abiotic stress
Giant reed
Isoprene emission
Phosphorus
Salinity
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Objavljeno v RUNG: 20.04.2020; Ogledov: 2827; Prenosov: 0
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