Periodic Reporting for period 4 - PyroTRACH (Pyrogenic TRansformations Affecting Climate and Health)
Reporting period: 2021-12-01 to 2023-05-31
We are addressing the topic of biomass burning (BB) and how it can affect particulate matter (aerosol) levels in the atmosphere. This research is important for society because aerosol from BB is highly toxic, interacts with solar radiation and can affect cloud formation and evolution. Considering this, the increased prevalence and extent of biomass burning from wildfires and domestic use and its long residence time in the atmosphere means that BB aerosol can (and has) large impacts on climate, ecosystems and public health. These impacts are highly uncertain, largely owing to our inability to track BB particulate matter and the evolution of their properties throughout most of its atmospheric lifetime. PyroTRACH addresses these uncertainties by: i) deriving new markers of biomass burning with an atmospheric lifetime that exceeds the current limitation of about a day, ii) measuring highly uncertain but critically-important climate- and health- relevant properties of aerosols both from wildfire events that occur during summertime and from BB for heating purposes during wintertime in highly populated urban environments, iii) applying this new knowledge to quantify the contribution of biomass burning to aerosol in the Mediterranean region, and quantify its impacts on climate and public health.
All aspects of the proposed project are being worked on. More specifically:
1. We have been carrying ambient sampling of particulate matter influenced by domestic biomass burning in urban settings (Athens and Patras, Greece; e.g. https://twitter.com/pyrotrach/status/1260532378503692288) during summer and winter periods from the beginning of the project. Samples are also collected from the remote site of Finokalia and Heraklion, Crete (e.g. https://twitter.com/LAPI_epfl/status/1278377339936702464) to capture wildfire plumes from a range of distances (ranging from nearby islands, to mainland Greece, Balkans or Russia). This large range of distance from the source means that the atmospheric processing and ageing of the smoke varies considerably from sample to sample, which is a requirement for addressing the PyroTRACH objectives. Additional samples of opportunities from all over the world (obtained through collaborations and other projects) are also added to our archive for analysis to obtain a global perpective of biomass burning impacts.
2. We have also been systematically carrying out laboratory experiments, where smoke is generated from a variety of facilities and combustion conditions (wood stove, fireplace, pellet stove) and introduced into the FORTH environmental chamber facility (e.g. https://twitter.com/LAPI_epfl/status/1252800291424088064) that replicates the conditions found in the atmosphere. In this facility, the smoke samples are “aged” in the chamber, as they would in the atmosphere under specific “regimes”– the main ones being nighttime vs. daytime conditions and humid vs. dry). Over time during these aging experiments, we follow how the chemistry and properties of the smoke particles change.
3. We are also carrying out campaign intensives (e.g. https://twitter.com/LAPI_epfl/status/1156596691941941254 https://twitter.com/pyrotrach/status/1271231836656668672 ) where ambient samples influenced by biomass burning smoke are comprehensively characterized, and also further aged – under controlled conditions – with portable environmental chambers deployed in the field. This controlled aging of ambient particles allows us to follow the properties of BB smoke when it is aged well beyond anything feasible in the FORTH chamber facility, and thus provides breakthrough understanding of the most aged particles from BB.
All biomass burning samples are analyzed for the chemical markers and characteristics related to their ability to absorb light (“brown carbon”) as well as their ability to generate radicals in-vivo (“oxidative potential”) and provide other sources of toxicity (polyaromatic hydrocarbons and their oxidized counterparts) that are associated with adverse health impacts upon inhalation. .
We have also been working on modeling biomass burning emissions, their chemical evolution and properties (Brown Carbon and Oxidative Potential) with the PMCAMx SR framework established by the group at FORTH.
Key results so far can be summarized as follows:
1. Biomass burning emits considerable amounts of Brown Carbon, a significant fraction of which decays ("photobleaches") a few hours after emission. A fraction however, composed of very large molecules emitted directly from biomass burning, is quite resilient to oxidation and remains brown after a few days of aging. This resilient brown carbon is uniquely related to biomass burning, causes persistent climate warming and carries the potential to be used as a marker for aged biomass burning.
2. Biomass burning is highly toxic, associated with high levels of oxidative potential. From analysis of ambient samples collected to date, we find that the toxicity of ambient aerosol increases as it ages in the atmosphere, increasing up to four times the values seen in fresh smoke. This means that smoke - even if it is highly diluted - can still cause adverse impacts to populations when breathing it.
3. Biomass burning is a major contributor to the total oxidative potential of aerosol in wintertime urban environments such as Athens, Greece.
1. We have been carrying ambient sampling of particulate matter influenced by domestic biomass burning in urban settings (Athens and Patras, Greece; e.g. https://twitter.com/pyrotrach/status/1260532378503692288) during summer and winter periods from the beginning of the project. Samples are also collected from the remote site of Finokalia and Heraklion, Crete (e.g. https://twitter.com/LAPI_epfl/status/1278377339936702464) to capture wildfire plumes from a range of distances (ranging from nearby islands, to mainland Greece, Balkans or Russia). This large range of distance from the source means that the atmospheric processing and ageing of the smoke varies considerably from sample to sample, which is a requirement for addressing the PyroTRACH objectives. Additional samples of opportunities from all over the world (obtained through collaborations and other projects) are also added to our archive for analysis to obtain a global perpective of biomass burning impacts.
2. We have also been systematically carrying out laboratory experiments, where smoke is generated from a variety of facilities and combustion conditions (wood stove, fireplace, pellet stove) and introduced into the FORTH environmental chamber facility (e.g. https://twitter.com/LAPI_epfl/status/1252800291424088064) that replicates the conditions found in the atmosphere. In this facility, the smoke samples are “aged” in the chamber, as they would in the atmosphere under specific “regimes”– the main ones being nighttime vs. daytime conditions and humid vs. dry). Over time during these aging experiments, we follow how the chemistry and properties of the smoke particles change.
3. We are also carrying out campaign intensives (e.g. https://twitter.com/LAPI_epfl/status/1156596691941941254 https://twitter.com/pyrotrach/status/1271231836656668672 ) where ambient samples influenced by biomass burning smoke are comprehensively characterized, and also further aged – under controlled conditions – with portable environmental chambers deployed in the field. This controlled aging of ambient particles allows us to follow the properties of BB smoke when it is aged well beyond anything feasible in the FORTH chamber facility, and thus provides breakthrough understanding of the most aged particles from BB.
All biomass burning samples are analyzed for the chemical markers and characteristics related to their ability to absorb light (“brown carbon”) as well as their ability to generate radicals in-vivo (“oxidative potential”) and provide other sources of toxicity (polyaromatic hydrocarbons and their oxidized counterparts) that are associated with adverse health impacts upon inhalation. .
We have also been working on modeling biomass burning emissions, their chemical evolution and properties (Brown Carbon and Oxidative Potential) with the PMCAMx SR framework established by the group at FORTH.
Key results so far can be summarized as follows:
1. Biomass burning emits considerable amounts of Brown Carbon, a significant fraction of which decays ("photobleaches") a few hours after emission. A fraction however, composed of very large molecules emitted directly from biomass burning, is quite resilient to oxidation and remains brown after a few days of aging. This resilient brown carbon is uniquely related to biomass burning, causes persistent climate warming and carries the potential to be used as a marker for aged biomass burning.
2. Biomass burning is highly toxic, associated with high levels of oxidative potential. From analysis of ambient samples collected to date, we find that the toxicity of ambient aerosol increases as it ages in the atmosphere, increasing up to four times the values seen in fresh smoke. This means that smoke - even if it is highly diluted - can still cause adverse impacts to populations when breathing it.
3. Biomass burning is a major contributor to the total oxidative potential of aerosol in wintertime urban environments such as Athens, Greece.
Every aspect of the PyroTRACH project pushes the state of the art in understanding biomass burning aspects on health and climate. This is because for the first time we have been able to unravel how particles from biomass burning change from emission to final deposition in the atmosphere, after multiple days of residence. By the end of the project, we will have established the degree to which "brown carbon" in BB particles continue to absorb after may days of residence in the atmosphere, as well as how their toxicity changes. Particularly important will be the ability to understand how daytime and nighttime chemistry (which is vastly different) shapes the brown carbon and toxicity profile of BB aerosol. The latter is extremely important, given that BB emissions in urban envionments often occur at nighttime - and changes in toxicity and brown carbon content may be significant and have an unknown impact on pubic health and climate. We also expect to identify robust mrkers of BB aerosol in very aged aerosol (results to date strongly support that) while we will continue to explore the possibility of quantifying the chemical regimes (daytime/nightttime chemistry, dry/humid conditions) using additional characteristic chemical or nonconventional markers. By combining the state of the art instrumentation, analysis and modeling of all our results, at the end of PyroTRACH we expect to have a vastly revised understanding of how BB aerosol impacts climate and health.