Search for: All records

There is growing concern about sensory pollutants affecting ecological communities. Anthropogenically enhanced oxidants [ozone (O₃) and nitrate radicals (NO₃)] rapidly degrade floral scents, potentially reducing pollinator attraction to flowers. However, the physiological and behavioral impacts on pollinators and plant fitness are unknown. Using a nocturnal flower-moth system, we found that atmospherically relevant concentrations of NO₃eliminate flower visitation by moths, and the reaction of NO₃with a subset of monoterpenes is what reduces the scent’s attractiveness. Global atmospheric models of floral scent oxidation reveal that pollinators in certain urban areas may have a reduced ability to perceive and navigate to flowers. These results illustrate the impact of anthropogenic pollutants on an animal’s olfactory ability and indicate that such pollutants may be critical regulators of global pollination.

Wildfires are important sources of atmospheric reactive nitrogen. The reactive nitrogen species partitioning generally depends on fire characteristics. One reactive nitrogen compound, nitrous acid (HONO), is a source of hydroxyl radicals and nitric oxide, which can impact the oxidizing capacity of the atmosphere and fire plume chemistry and composition. We study the Australian wildfire season of 2019–2020, known as Black Summer, where numerous large and intense wildfires burned throughout the continent. We use HONO and nitrogen dioxide (NO₂) from the TROPOspheric Monitoring Instrument (TROPOMI) and fire radiative power (FRP) from the Visible Infrared Imaging Radiometer Suite to investigate HONO and NO₂relationships with fire characteristics. The ratio of HONO to NO₂increases linearly with FRP both in Australia and globally. Both Australian and global fire relationships depend strongly on land cover type. These relationships can be applied to emission inventories to improve wildfire emission representation in models.

As part of the WINTER (Wintertime Investigation of Transport, Emissions, and Reactivity) campaign, a Particle‐into‐Liquid Sampler with a fraction collector was flown aboard the National Center for Atmospheric Research C‐130 aircraft. Two‐minute integrated liquid samples containing dissolved fine particulate matter (PM₁) species were collected and analyzed off‐line for the smoke marker levoglucosan using high‐performance anion‐exchange chromatography‐pulsed amperometric detection to compare levoglucosan with aerosol mass spectrometer (AMS) biomass burning markers and investigate the contribution from residential burning during the study. Levoglucosan was correlated with AMS organic aerosol (R² = 0.49) and with carbon monoxide (CO;R² = 0.51) for all flights. Levoglucosan was not correlated with the inorganic smoke marker water‐soluble potassium but was correlated with the AMS markers ∆C₂H₄O₂⁺(high resolution,R² = 0.60) and ∆m/z60 (unit mass resolution,R² = 0.61). However, at low levoglucosan, AMS markers deviated potentially due to interferences from other sources or differences with the species captured by the AMS markers. Analysis of levoglucosan changes relative to carbon monoxide as plumes advected from source regions showed no systematic levoglucosan loss for plumes up to 20 hr old. Based on literature residential burning source ratios and measured levoglucosan, contributions of organic carbon (OC) due to residential burning were estimated. The contribution ranged from ~30 to 100% of the OC, with significant variability depending on the source ratio used; however, the results show that biomass burning was a significant PM₁OC source across the entire sampling region. A GEOS‐Chem model simulation predicted significantly less smoke contribution.