UNIPAR has been coupled with the Comprehensive Air Quality Model with Extensions (CAMx) air quality model, which largely improved the prediction of SOA mass in three different regions: East Asia (KORUS-AQ in 2016); Central Valley, California (the National Chemical Speciation Monitoring Network in 2018 provided by the Bay Area Air Quality Management District [BAAQMD]), and the Southern U.S. (2022 Air Data from the U.S. EPA). The implement of heterogeneous chemistry in aqueous phase in CAMx=UNIAPR significantly improve the analysis of impacts of humidity and NOx levels on SOA formation.
Harmful algal blooms (HABs) are a major health problem around the World. Reports of HABs have drastically increased over the past 50 years as a result of warmer climate conditions and increased pollution, coastal development, and other factors.
Algal aerosol from red tide breaks
Karenia (K.) brevis is a dinoflagellate indigenous to the waters of the Gulf of Mexico and the Caribbean. Its blooms recur in native regions and multiply to neighboring coastlines. K. brevis is the photosynthetic organism primarily responsible for harmful algae blooms known as “red tide” and produces a harmful toxin, known as brevetoxin (BTx). Scientists report Florida’s sequential hits from Hurricanes Helene and Milton are fueling the outbreak of toxic algae blooms that appeared before the Hurricanes slammed the Gulf coast.
Algal aerosol from cyanobacterial blooms in fresh water and estuaries
Several strains of blue-green algae, or cyanobacteria produce HABs in freshwater systems across the U.S. .Cyanobacterial algae produce toxins, such as Microcystin-LR (MC-LR), that can make animals and people sick. These toxins are classically associated with acute liver and renal toxicity following ingestion which can lead to mortality of people and aquatic organisms,
Impacts of algal aerosol on respiratory health
Algae toxins are aerosolized with sea spray aerosol (SSA) or fresh-water spray aerosol. Algal aerosol and toxins can be carried inland by winds. One of the major organ systems targeted by algal aerosol and toxins is the respiratory system. For example, studies suggest that coastal residents may experience higher rates of respiratory diagnoses during red tide periods compared to non-red tide periods.
Studies at UF Atmospheric Chemistry Lab.
- Atmospheric processes of algal toxins
- Exposure of in vitro respiratory cells to algal aerosol and toxins via Collaboratory works with public health department
- Oxidative potentials of algal aerosol collected at fields or chamber simulations
- Development of the Harmful Algal Aerosol Reaction (HAAR) model to simulation the oxidative degradation of algal toxins
- Enrichment of algal toxins in sea spray aerosol or lake spray aerosol
What are the secondary organic aerosol (SOA)?
As a class, secondary organic aerosols (SOA) are air pollutants formed through complex interaction of sunlight, volatile organic compounds emitted from trees, plants, automobiles, industries and other airborne chemical species (i.e., NOx and SO2). SOA is a major constituents of the fine particulate matter (PM2.5), which has been known to cause the adverse effects on pulmonary health and climate.
What is our laboratory doing?
SOA is under investigation in a multidisciplinary approach to understand how SOA contribute to airborne fine particulate matter, the possible public health and atmospheric effects. Our research team is studying SOA to answer questions below:
- What are the most common precursor of SOAs in the tropospheric atmosphere?
- What are the mechanisms of the formation of SOAs in the atmosphere?
- What is their chemical composition?
- What are the fate of the SOAs as they travel through the atmosphere?
- What are their health effects?
- What are their effects on climate forcing?
UF-APHOR chamber
The Atmospheric PHotochemical Outdoor Reactor (UF-APHOR) is a state of the art science facility which uses natural sunlight to enable more precise replication of atmospheric chemistry. The UF-APHOR is located on the top of Black Hall (29.64185° N, –82.347883° W) at the University Florida. The large chamber volume (52 m3 + 52 m3) provides enough air to sample for multiple analyses and the dual chambers allow for two simultaneously controlled experiments to be performed under the same meteorological conditions. The gaseous compounds and aerosols generated in the chamber are directly carried to various analytical instruments in the Atmospheric Chemistry Laboratory for the characterization of oxidation products using spectroscopic, thermal, and chromatographic methods. The resulting chamber data have been applied to the discovery of new chemistry in aerosol and development of aerosol models.
Indoor Reactors
Two 2.0 m3 indoor Teflon film reactors are housed in the Atmospheric Chemistry Laboratory. Indoor chambers are used to conduct humidity controlled chamber experiments at constant temperature. The reactors were specially designed to be compressible to half their volume (i.e., into 1 m3) without dilution due to sampling and analyses. The indoor chamber is used to test analytical methods prior to scale up to the experiment using UF-APHOR or field sampling.
UNIPAR SOA model
Our laboratory’s recent research efforts have improved the state-of-the science-art via the development of the UNIfied Partitioning-Aerosol phase Reaction model (UNIPAR), which utilizes explicit gas chemistry to predict SOA formation from multiphase reactions. UNIPAR vastly improved the accuracy of chamber generated SOA mass predictions. For example, the UNIPAR prediction of isoprene SOA in the presence of inorganic salted wet aerosol is 3-7 times greater than the SOA mass predicted by partitioning alone, suggesting the importance of in-particle chemistry in SOA growth.
UNIPAR captures the influence of NOx on SOA formation via modulation of the volatility-reactivity distribution of oxidized products derived from the representation of near-explicit gas mechanisms. UNIPAR comprehensively predicts the SOA mass (OMT) by incorporating multiphase partitioning (OMP) of SVOCs between gas, in, and or phases and by representing aerosol chemistry (oligomerization, acid-catalyzed reactions, and OS formation) (OMAR) of all known SVOC under broad ranges of aerosol acidity and humidity to form both the dry and the wet inorganic salt aerosols. Thus, UNIPAR will improve the accuracy of SOA mass predictions, which are under predicted by current regional models.
Heterogeneous reactions on mineral dust particles
Mineral dust particles are one of the largest contributors to particle mass loading in the ambient atmosphere, with estimated annual emission of 1000−3000 Tg yr. The Gobi desert in Mongolia and northern China and the Sahara desert in Northern Africa are the most important sources of mineral dust particles. In arid environments such as the Southwestern U.S., eolian processes also cause soil erosion, transport mineral dust, and deposit the dust on surfaces where it may intrude. Mineral dust has a wide impact on the Earth System by affecting visibility degradation, the radiative forcing, cloud formation, plant nutrition, and oceanic biogeochemical cycles. During long-range transport, dust particles provide significant surfaces for the heterogeneous reaction with atmospheric trace gases such as SO2, O3, NOx, H2O2, and hydrocarbons. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote the oxidation of air pollutants, but its prediction is not fully taken by the current models.
What is our laboratory doing?
- The impact of authentic mineral dust particles sourced from the Gobi Desert (GDD particles) on the kinetic uptake coefficient of SO2 has been comprehensively studied under varying environments (humidity, O3, NOx) using the indoor chamber and the UF-APHOR chamber.
- The Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on the formation of nitrate and sulfate under various environments.
- Application of the AMAR model to regional scale models
PM Health Effect
Health concerns associated with exposure to air pollution are driven by enhanced risk of mortality, reproductive effects, and cardiopulmonary and lung disease. The smaller-sized particles – those 2.5 micrometers or less in diameter, called PM2.5 – are of greatest health concern because they can reach deep inside the lungs. Both primary combustion particulates and SOA are PM2.5 and influence daily base air quality. Primary combustion particulates are recognized as causative agents however increasing attention has been paid to secondary organic aerosol (SOA) produced from atmospheric transformation of hydrocarbons.
What is our laboratory doing?
- Development of in vitro exposure technology
- Electrostatic Precipitator (ESP): ESP system allows for online exposure of cells via direct dispersion of aerosol onto the air-liquid interface. We have been improving the particle delivery to in vitro cell cultures and derived a dose model to assess health effects of particulate matter.
- Magnetic Precipitator: The noble technology using magnetic nanoparticle (MNP) to deliver SOA onto the biological systems has been invented by our laboratory. SOA was directly core-coated on preexisting MNPs, and delivered to a culture membrane implanting in vitro epithelial cells under a magnetic field.
- In vitro studies of SOA: Through collaborative work with pulmonary toxicologists, our lab deliver SOA to the air interface of lung epithelial cells using a novel aerosol delivery system and assess cellular ROS production, viral infectivity, mitochondrial function and lipid composition.
- Development of cell-free detection methods to determine toxicity of particulate matter: We have been studying the reactivity of SOA with amino acids by using cell-free chemical assays and uncover the molecular mechanisms behind the impact of SOA on biological systems at the cellular level in vitro
