Biogenic Aerosol in the Artic from Eight Years of MSA Data from Ny Ålesund (Svalbard Islands) and Thule (Greenland)

In remote marine areas, biogenic productivity and atmospheric particulate are coupled through dimethylsulfide (DMS) emission by phytoplankton. Once in the atmosphere, the gaseous DMS is oxidized to produce H2SO4 and methanesulfonic acid (MSA); both species can a ect the formation of cloud condensation nuclei. This study analyses eight years of biogenic aerosol evolution and variability at two Arctic sites: Thule (76.5 N, 68.8 W) and Ny Ålesund (78.9 N, 11.9 E). Sea ice plays a key role in determining the MSA concentration in polar regions. At the beginning of the melting season, in April, up to June, the biogenic aerosol concentration appears inversely correlated with sea ice extent and area, and positively correlated with the extent of the ice-free area in the marginal ice zone (IF-MIZ). The upper ocean stratification induced by sea ice melting might have a role in these correlations, since the springtime formation of this surface layer regulates the accumulation of phytoplankton and nutrients, allowing the DMS to escape from the sea to the atmosphere. The multiyear analysis reveals a progressive decrease in MSA concentration in May at Thule and an increase in July August at Ny Ålesund. Therefore, while the MSA seasonal evolution is mainly related with the sea ice retreat in April, May, and June, the IF-MIZ extent appears as the main factor a ecting the longer-term behavior of MSA.MIUR PRIN 2007 and PRIN 2009, PNRA 2010-2012, PNRA 2015-2016, PNRA 2016-2018Publishedid 3495A. Ricerche polari e paleoclimaJCR Journa

On the Radiative Impact of Biomass-Burning Aerosols in the Arctic: The August 2017 Case Study

Boreal fires have increased during the last years and are projected to become more intense and frequent as a consequence of climate change. Wildfires produce a wide range of effects on the Arctic climate and ecosystem, and understanding these effects is crucial for predicting the future evolution of the Arctic region. This study focuses on the impact of the long-range transport of biomass-burning aerosol into the atmosphere and the corresponding radiative perturbation in the shortwave frequency range. As a case study, we investigate an intense biomass-burning (BB) event which took place in summer 2017 in Canada and subsequent northeastward transport of gases and particles in the plume leading to exceptionally high values (0.86) of Aerosol Optical Depth (AOD) at 500 nm measured in northwestern Greenland on 21 August 2017. This work characterizes the BB plume measured at the Thule High Arctic Atmospheric Observatory (THAAO; 76.53° N, °68.74° W) in August 2017 by assessing the associated shortwave aerosol direct radiative impact over the THAAO and extending this evaluation over the broader region (60° N-80° N, 110° W-0° E). The radiative transfer simulations with MODTRAN6.0 estimated an aerosol heating rate of up to 0.5 K/day in the upper aerosol layer (8-12 km). The direct aerosol radiative effect (ARE) vertical profile shows a maximum negative value of -45.4 Wm-2 for a 78° solar zenith angle above THAAO at 3 km altitude. A cumulative surface ARE of -127.5 TW is estimated to have occurred on 21 August 2017 over a portion (3.1 10^6 km2) of the considered domain (60° N-80° N, 110° W-0° E). ARE regional mean daily values over the same portion of the domain vary between -65 and -25 Wm-2. Although this is a limited temporal event, this effect can have significant influence on the Arctic radiative budget, especially in the anticipated scenario of increasing wildfires

Relationships linking primary production, sea ice melting, and biogenic aerosol in the Arctic

AbstractThis study examines the relationships linking methanesulfonic acid (MSA, arising from the atmospheric oxidation of the biogenic dimethylsulfide, DMS) in atmospheric aerosol, satellite-derived chlorophyll a (Chl-a), and oceanic primary production (PP), also as a function of sea ice melting (SIM) and extension of the ice free area in the marginal ice zone (IF-MIZ) in the Arctic. MSA was determined in PM10 samples collected over the period 2010–2012 at two Arctic sites, Ny Ålesund (78.9°N, 11.9°E), Svalbard islands, and Thule Air Base (76.5°N, 68.8°W), Greenland. PP is calculated by means of a bio-optical, physiologically based, semi-analytical model in the potential source areas located in the surrounding oceanic regions (Barents and Greenland Seas for Ny Ålesund, and Baffin Bay for Thule). Chl-a peaks in May in the Barents sea and in the Baffin Bay, and has maxima in June in the Greenland sea; PP follows the same seasonal pattern of Chl-a, although the differences in absolute values of PP in the three seas during the blooms are less marked than for Chl-a. MSA shows a better correlation with PP than with Chl-a, besides, the source intensity (expressed by PP) is able to explain more than 30% of the MSA variability at the two sites; the other factors explaining the MSA variability are taxonomic differences in the phytoplanktonic assemblages, and transport processes from the DMS source areas to the sampling sites. The taxonomic differences are also evident from the slopes of the correlation plots between MSA and PP: similar slopes (in the range 34.2–36.2 ng m−3of MSA/(gC m−2 d−1)) are found for the correlation between MSA at Ny Ålesund and PP in Barents Sea, and between MSA at Thule and PP in the Baffin Bay; conversely, the slope of the correlation between MSA at Ny Ålesund and PP in the Greenland Sea in summer is smaller (16.7 ng m−3of MSA/(gC m−2 d−1)). This is due to the fact that DMS emission from the Barents Sea and Baffin Bay is mainly related to the MIZ diatoms, which are prolific DMS producers, whereas in the Greenland Sea the DMS peak is related to an offshore pelagic bloom where low-DMS producer species are present. The sea ice dynamic plays a key role in determining MSA concentration in the Arctic, and a good correlation between MSA and SIM (slope = 39 ng m−3 of MSA/106 km2 SIM) and between MSA and IF-MIZ (slope = 56 ng m−3 of MSA/106 km2 IF-MIZ) is found for the cases attributable to bloomings of diatoms in the MIZ. Such relationships are calculated by combining the data sets from the two sites and suggest that PP is related to sea ice melting and to the extension of marginal sea ice areas, and that these factors are the main drivers for MSA concentrations at the considered Arctic sites

Long Term Running Biphasically Improves Methylglyoxal-Related Metabolism, Redox Homeostasis and Neurotrophic Support within Adult Mouse Brain Cortex

Oxidative stress and neurotrophic support decline seem to be crucially involved in brain aging. Emerging evidences indicate the pro-oxidant methylglyoxal (MG) as a key player in the age-related dicarbonyl stress and molecular damage within the central nervous system. Although exercise promotes the overproduction of reactive oxygen species, habitual exercise may retard cellular aging and reduce the age-dependent cognitive decline through hormetic adaptations, yet molecular mechanisms underlying beneficial effects of exercise are still largely unclear. In particular, whereas adaptive responses induced by exercise initiated in youth have been broadly investigated, the effects of chronic and moderate exercise begun in adult age on biochemical hallmarks of very early senescence in mammal brains have not been extensively studied. This research investigated whether a long-term, forced and moderate running initiated in adult age may affect the interplay between the redox-related profile and the oxidative-/MG-dependent molecular damage patterns in CD1 female mice cortices; as well, we investigated possible exercise-induced effects on the activity of the brain derived neurotrophic factor (BDNF)-dependent pathway. Our findings suggested that after a transient imbalance in almost all parameters investigated, the lately-initiated exercise regimen strongly reduced molecular damage profiles in brains of adult mice, by enhancing activities of the main ROS- and MG-targeting scavenging systems, as well as by preserving the BDNF-dependent signaling through the transition from adult to middle age

Complete disaggregation of MCF-7-derived breast tumour spheroids with very low concentrations of \u3b1-mangostin loaded in CD44 thioaptamer-tagged nanoparticles

Background: \u3b1-Mangostin (\u3b1MG) is a natural substance that exerts a wide range of antitumor effects. Recently, we described that free \u3b1MG was able to dissociate multicellular tumour spheroids (MCTSs) generated from breast carcinoma cells and to reduce their cellular viability and motility. Here, \u3b1MG was encapsulated into lipidic nanoparticles (NPs), conjugated or not to a CD44 thioaptamer, and the anticancer action evaluated against MCF-7 breast MCTSs. Methods: NPs containing \u3b1MG were formulated with a core of polylactic-co-glycolyc acid. Some of them were decorated with a CD44 thioaptamer using as catalysts 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. Both size and density of MCF-7-derived MCTSs were monitored during 72 h of treatment with NPs carrying 0.1, 0.5 and 1.0 \ub5g/ml final concentrations of \u3b1MG. MCTSs were cultured on Matrigel or gelatine to better simulate the extracellular environment. Results: The NPs without thioaptamer and conveying 0.1 \ub5g/ml \u3b1MG caused a significant dissociation of the MCTSs grown in gelatine after 24 h of treatment (p < 0.01). The most significant disaggregation of MCTSs was obtained using NPs carrying 0.5 \ub5g/ml \u3b1MG (p < 0.01). A similar dissociating effect was observed when MCTSs were cultured in Matrigel under the same conditions for 48 \u2013 72 h. By contrast, only concentrations over 1.0 \ub5g/ml of free \u3b1MG were able to provoke a damage to MCTSs, consisting in a substantial reduction in their size (p < 0.05). Since the MCTS dissociation induced by \u3b1MG-loaded NPs occurred only in the presence of Matrigel or gelatine, an impairment of cell contacts to collagen fibres was likely responsible of this effect. Finally, the treatment of MCTSs with \u3b1MG-loaded NPs that were conjugated to the CD44 thioaptamer caused a similar decrease in density but a lower expansion of the spheroid, suggesting that a significant number of cells were died or arrested in cycle. Conclusion: Very low concentrations of \u3b1MG delivered by lipidic NPs are sufficient to provoke a substantial disaggregation of MCF-7 MCTSs that involves cell-to-collagen contacts. Similarly, the treatment of MCTSs with NPs conjugated to a CD44 thioaptamer leads to MCTS dissociation but through a more damaging action that causes also a reduction in cell number

Accelerating Climate Action: A just transition in a post-Covid era. Book of abstracts, 9th SISC Annual Conference (online, 22-24 Set 2021)

Extended and intense biomass burning fires occurred in Northern Canada and on the Greenlandic West coast during summer 2017. The smoke plume emitted into the atmosphere was transported and spread in the Arctic, producing one of the most significant impacts ever observed in the region. Evidence of Canadian and Greenlandic wildfires was recorded at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5°N, 68.8°W, www.thuleatmos-it.it) by a suite of instruments managed by ENEA, INGV, Univ. of Florence, and NCAR. Chemical tracers such as CO, HCN, H2CO, C2H6, and NH3 were measured in the atmospheric column above Thule from 19 August to 23 August by an FTIR. The aerosol optical depth measured by the AERONET sunphotometer was dominated by the fine fraction, reaching a peak value of about 0.86 on 21 August. An air sampler monitored several wildfire compounds at a 48-hour resolution. Groundbased radiometers allowed the quantification of the surface radiation budget at THAAO. Backward trajectories produced through HYSPLIT simulations (Stein et al., 2015) were also employed to understand the atmospheric dynamics indicating the origin of the transported smoke. MODTRAN6.0 radiative transfer model (Berk et al., 2014) was used to estimate the aerosol radiative effect (ARE) and the heating rate profiles at 78° SZA. Measured temperature profiles, integrated water vapour, surface albedo, spectral AOD and aerosol extinction profiles from CALIOP onboard CALIPSO satellite were used as model input. The shortwave ARE at the surface was -43.7 W/m2 at 78° solar zenith angle (SZA) for AOD=0.626. The peak aerosol heating rate (+0.5 K/day) was reached within the aerosol layer between 8 and 12 km, while the maximum radiative effect (-45.4 W/m2) was found at 3 km, below the most extensive aerosol layer. The regional impact of the event observed between 15 and 25 August was investigated using MODTRAN to model the aerosol radiative effect efficiency (AREE) with measurements of AOD and surface albedo over land retrieved from MODIS. Instead, albedo data over the ocean were obtained from Jin et al. (2004). The radiative transfer model was fed with the atmospheric properties used in the ARE simulation at THAAO. The values of aerosol radiative effect efficiency (AREE) span from -3 W/m2 to -132 W/m2, depending on surface albedo and solar zenith angle. The fire plume covered a vast portion of the Arctic, with large values of the AOD reaching the eastern Greenlandic coast and with the shortwave ARE lasting for a few days. In particular, we calculated a cumulative ARE during the considered period and found a negative peak value of -120 TW on 21-22 August over the Arctic sector between 60°N - 80°N and 110°W - 0°E. Instead, the mean daily ARE shows values between -65 and -25 W/m2 between 15 and 25 August, being influenced by really large AOD values mainly during the first part of the period over northern Canada. This large amount of aerosol is also expected to influence cloud properties in the Arctic, producing significant indirect radiative effects. References Berk, A., P. Conforti, R. Kennett, T. Perkins, F. Hawes and J. van den Bosch (2014), "MODTRAN6: a major upgrade of the MODTRAN radiative transfer code", Proc. SPIE 9088, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XX, 90880H, 9088, 1-7. Stein, A.F., R.R. Draxler, G.D. Rolph, B.J.B. Stunder, M.D. Cohen and F. Ngan (2015), “Noaa’s hysplit atmospheric transport and dispersion modeling system”, Bulletin of the American Meteorological Society, 96(12), 2059–2077. Jin, Z., T.P. Charlock, W.L. Smith and K. Rutledge (2004), “A parameterization of ocean surface albedo”, Geophysical Research Letters, 31(22), 1–4