Implementation and Impacts of Surface and Blowing Snow Sources of Arctic Bromine Activation Within WRF-Chem 4.1.1

Arctic halogens reduce ozone in the northern mid-latitudes

While the dominant role of halogens in Arctic ozone loss during spring has been widely studied in the last decades, the impact of sea-ice halogens on surface ozone abundance over the northern hemisphere (NH) mid-latitudes remains unquantified. Here, we use a state-of-the-art global chemistry-climate model including polar halogens (Cl, Br, and I), which reproduces Arctic ozone seasonality, to show that Arctic sea-ice halogens reduce surface ozone in the NH mid-latitudes (47°N to 60°N) by ~11% during spring. This background ozone reduction follows the southward export of ozone-poor and halogen-rich air masses from the Arctic through polar front intrusions toward lower latitudes, reducing the springtime tropospheric ozone column within the NH mid-latitudes by ~4%. Our results also show that the present-day influence of Arctic halogens on surface ozone destruction is comparatively smaller than in preindustrial times driven by changes in the chemical interplay between anthropogenic pollution and natural halogens. We conclude that the impact of Arctic sea-ice halogens on NH mid-latitude ozone abundance should be incorporated into global models to improve the representation of ozone seasonality.

Label-Free Identification of Carbonaceous Particles Using Nonlinear Optical Microscopy

The adverse health effects of ambient carbonaceous particles (CPs) such as carbon black (CB), black carbon (BC), and brown carbon (BrC) are becoming more evident and depend on their composition and emission source. Therefore, identifying and quantifying these particles in biological samples are important to better understand their toxicity. Here, we report the development of a nonlinear optical approach for the identification of CPs such as CB and BrC using imaging conditions compatible with biomedical samples. The unique visible light fingerprint of CB and BrC nanoparticles (NPs) upon illumination with a femtosecond (fs) pulsed laser at 1300 nm excitation wavelength is an effective approach for their identification in their biological context. The emission from spectral features of these CPs was investigated with time-domain fluorescence lifetime imaging (FLIM) to further support their identification. This study is performed for different types of CPs embedded in agarose gel as well as in in vitro mammalian cells. The unique nonlinear emissive behavior of CP NPs used for their label-free identification is further complementary with fluorophores typically used for specific staining of biological samples thus providing the relevant bio-context.

Carbonaceous Nanoparticle Air Pollution: Toxicity and Detection in Biological Samples

Among the different air pollutants, particulate matter (PM) is of great concern due to its abundant presence in the atmosphere, which results in adverse effects on the environment and human health. The different components of PM can be classified based on their physicochemical properties. Carbonaceous particles (CPs) constitute a major fraction of ultrafine PM and have the most harmful effects. Herein, we present a detailed overview of the main components of CPs, e.g., carbon black (CB), black carbon (BC), and brown carbon (BrC), from natural and anthropogenic sources. The emission sources and the adverse effects of CPs on the environment and human health are discussed. Particularly, we provide a detailed overview of the reported toxic effects of CPs in the human body, such as respiratory effects, cardiovascular effects, neurodegenerative effects, carcinogenic effects, etc. In addition, we also discuss the challenges faced by and limitations of the available analytical techniques for the qualitative and quantitative detection of CPs in atmospheric and biological samples. Considering the heterogeneous nature of CPs and biological samples, a detailed overview of different analytical techniques for the detection of CPs in (real-exposure) biological samples is also provided. This review provides useful insights into the classification, toxicity, and detection of CPs in biological samples.

Study of an Arctic blowing snow-induced bromine explosion event in Ny-Ålesund, Svalbard

Bromine explosion events (BEEs) are important processes that influence the atmospheric oxidation capacity, especially in the polar troposphere during spring. Although sea ice surface is thought to be a significant bromine source, bromine release mechanisms remain unclear. High-resolution ground-based observations of reactive bromine, such as BrO, are important for assessing the potential impacts on tropospheric ozone and evaluating chemical models. However, previous model studies paid little attention to Svalbard, which is surrounded by both open ocean and sea ice. In this paper, we present continuous BrO slant column densities and vertical column densities derived by Multi-Axis Differential Optical Absorption Spectroscopy deployed at Ny-Ålesund (78.92°N, 11.93°E) in March 2017. We focused on one BEE in mid-March, during which the vertical column densities of BrO surged from 4.26 × 10¹³ molecular cm^-2 to the peak at 1.23 × 10¹⁴ molecular cm^-2 on March 17, surface ozone depleted from a background level of 46.25 parts per billion by volume (ppbv) to 13.9 ppbv. This case study indicates that the BEE was strongly associated with blowing snow induced by the cyclone systems that approached Svalbard from March 14 to 18. By considering meteorological conditions, sea ice coverage, and airmass trajectory history, we demonstrate that sea salt aerosols (SSAs) from blowing snow on sea ice, rather than from open ocean, are attributed to the occurrence of this BEE. Model results from a parallelized-tropospheric offline model of chemistry and transport (p-TOMCAT) indicate that this BEE was mainly triggered by a blowing snow event associated with a low-pressure cyclone system. The concentration of blowing-snow-sourced SSAs surged to peak when the airmass pass across the sea-ice-covered area under high wind speed, which is a critical factor in the process of bromine explosion observed in Ny-Ålesund. Due to the coarse resolution, the possible delayed timing of bromine release from SSA and the model-data discrepancies still exist.