Study of chemical and optical properties of biomass burning aerosols during long-range transport events toward the arctic in Summer 2017

Producción CientíficaBiomass burning related aerosol episodes are becoming a serious threat to the radiative balance of the Arctic region. Since early July 2017 intense wildfires were recorded between August and September in Canada and Greenland, covering an area up to 4674 km2 in size. This paper describes the impact of these biomass burning (BB) events measured over Svalbard, using an ensemble of ground-based, columnar, and vertically-resolved techniques. BB influenced the aerosol chemistry via nitrates and oxalates, which exhibited an increase in their concentrations in all of size fractions, indicating the BB origin of particles. The absorption coefficient data (530 nm) at ground reached values up to 0.6 Mm–1, highlighting the impact of these BB events when compared to average Arctic background values, which do not exceed 0.05 Mm–1. The absorption behavior is fundamental as implies a subsequent atmospheric heating. At the same time, the AERONET Aerosol Optical Depth (AOD) data showed high values at stations located close to or in Canada (AOD over 2.0). Similarly, increased values of AODs were then observed in Svalbard, e.g., in Hornsund (daily average AODs exceeded 0.14 and reached hourly values up to 0.5). Elevated values of AODs were then registered in Sodankylä and Andenes (daily average AODs exceeding 0.150) a few days after the Svalbard observation of the event highlighting the BB columnar magnitude, which is crucial for the radiative impact. All the reported data suggest to rank the summer 2017 plume of aerosols as one of the biggest atmosphere related environmental problems over Svalbard region in last 10 years

Adverse biological effects of Milan urban PM looking for suitable molecular markers of exposure

The results presented summarise the ones obtained in the coordinated research project Tosca, which extensively analysed the impact of Milan urban PM on human health. The molecular markers of exposure and effects of seasonally and size-fractionated PMs (summer and winter PM10, PM2.5) were investigated in in vitro (human lung cell lines) and in vivo (mice) systems. The results obtained by the analyses of cytotoxic, pro-inflammatory and genotoxic parameters demonstrate that the biological responses are strongly dependent upon the PM samples seasonal and dimensional variability, that ultimately reflect their chemical composition and source. In fact summer PM10, enriched in crustal elements and endotoxins, was the most cytotoxic and pro-inflammatory fraction, while fine winter PMs induced genotoxic effects and xenobiotic metabolizing enzymes (like CYP1B1) production, likely as a consequence of the higher content in combustion derived particles reach in PAHs and heavy toxic metals. These outcomes outline the need of a detailed knowledge of the PMs physico-chemical composition on a local scale, coupled with the biological hazard directly associated to PM exposure. Apparently this is the only way allowing scientists and police-makers to establish the proper relationships between the respirable PM quantity/quality and the health outcomes described by clinicians and epidemiologists

In vitro effects of microbiologically characterized Milan particulate matter

AbstractMilan is one of the biggest cities in Italy characterized by a heavy automotive traffic. Air pollution is a deal of concern owing to the high concentration of particulate matter (PM10 and PM2.5) registered all over the year. Existing epidemiological data suggest an impact of PM on human health; however, experimental data on the biological effects of PM are still poorly investigated. In vitro results obtained after exposure to PM10 and PM2.5 sampled in Milan during winter and summer are reported here. PMs were characterized for their chemical and microbiological composition and tested to evaluate their potential toxicity in the human pulmonary cell line A549 and in the monocytes cell line THP-1. The chemical and microbiological analysis showed an evident seasonality in PM properties. Interestingly summer PMs contains mainly gram negative bacterial population while winter PMs gram positive, spore forming and possibly pathogenic, bacteria. PMs triggered different biological responses which are possibly related to the sampling season. Summer PMs elicited a higher pro-inflammatory potential that correlates to the high content of gram negative bacteria as detected by the microbiological characterization. On the other hand the winter PMs are able to induce cell cycle arrest, disrupting the normal microtubule organization in mitotic cells. The results obtained underline that the chemical properties of the PM are only in part responsible for the biological responses, since the biological components are of primary importance triggering endpoints such as inflammation