Aerosol Iron from Metal Production as a Secondary Source of Bioaccessible Iron

Linking Combustion-Derived Magnetite and Black Carbon: Insights from Magnetic Characterization of PM2.5 in Downwind East Asia

Combustion-derived magnetite has recently attracted attention for its health risks and potential impact on atmospheric heating/cooling. This study provides new observational insights into the relationship between black carbon (BC) and magnetite at a remote site in East Asia, Japan, focusing on combustion sources, seasonal trends, and potential overestimation of BC by the light-absorbing magnetite. Magnetic measurements of PM2.5 samples, complemented by detailed chemical analyses, reveal similar temporal variations between BC and magnetite while demonstrating that the relative abundance of magnetite to BC varies by combustion source, driving seasonal trends. Magnetite abundance during combustion episodes was found to follow the order: coal > oil > biomass, with mass concentrations roughly estimated via magnetization to be 9-10%, 5-6%, and <2% of BC, respectively. Furthermore, magnetite was estimated to contribute up to 5% of the BC absorption coefficient, suggesting the considerable overestimation of BC depending on the source. Although regionality and source mixing should be further verified, these findings show that magnetic measurements of archived samples can offer valuable contributions to reconstructing long-term combustion trends or overestimates in conventional observations of BC.

How Acid Iron Dissolution in Aged Dust Particles Responds to the Buffering Capacity of Carbonate Minerals during Asian Dust Storms

Aerosol deposition significantly impacts ocean ecosystems by providing bioavailable iron (Fe). Acid uptake during the transport of Fe-containing particles has been shown to cause Fe dissolution. However, carbonate in dust particles affects the Fe acidification process, influencing Fe dissolution. Here, we carried out atmospheric observations and modeling to show that Fe solubility substantially increased from locations near dust sources to downwind regions in aged dust particles with pH > 3, driven by proton-promoted dissolution. We found that Fe solubility remained low when Ca solubility was under 45 ± 5%, but increased with Ca solubility when it was above 45 ± 5%. Moreover, we found that Fe dissolved in aqueous Ca-nitrate coatings on Fe-containing dust particles. Our results suggest that the mixing state and buffering capacity of carbonate and Fe minerals should be represented in atmospheric biogeochemical models to more accurately simulate acid Fe dissolution processes.

Impacts of atmospheric particulate matter deposition on phytoplankton: A review

In many rapidly urbanizing and industrializing countries, atmospheric pollution causes severe environmental problems and compromises the health of humans and ecosystems. Atmospheric emissions, which encompass gases and particulate matter, can be transported back to the earth's surface through atmospheric deposition. Atmospheric deposition supplies chemical species that can serve as nutrients and/or toxins to aquatic ecosystems, resulting in wide-ranging responses of aquatic organisms. Among the aquatic organisms, phytoplankton is the basis of the aquatic food web and is a key player in global primary production. Atmospheric deposition alters nutrient availability and thus influences phytoplankton species abundance and composition. This review provides a comprehensive overview of the physiological responses of phytoplankton resulting from the atmospheric deposition of trace metals, nitrogen-containing compounds, phosphorus-containing compounds, and sulfur-containing compounds in particulate matter into aquatic ecosystems. Knowledge gaps and critical areas for future studies are also discussed.

Possible enhancement in ocean productivity associated with wildfire-derived nutrient and black carbon deposition in the Arctic Ocean in 2019-2021

The Arctic is severely affected by climate change and various forms of environmental pollution. Enriched with nutrients and light-absorbing compounds, the wildfire plume has the potential to affect biological carbon fixation and sequestration within the Arctic Ocean. In this study, we utilized satellite-derived oceanic data (phytoplankton and sea ice) and atmospheric reanalysis products (black carbon, BC, indicative of wildfire impact) to evaluate the effect of the pronounced increase in wildfires from 2019 to 2021 on the East Siberian Sea. During these years, chlorophyll-a levels rose by ∼213 % compared to the previous decadal average, which had notably lower wildfire activities. This increase in chlorophyll-a is attributable to the deposition of nitrogen from the wildfire plume. Concurrently, the period required for sea ice concentration to decrease by 25 % was on average ∼ 10 days shorter than usual. This suggests that BC-induced acceleration of sea ice melting might extend the growing season for phytoplankton.

Response of trace elements in urban deposition to emissions in a northwestern river valley type city: 2010-2021

Anthropogenic activities release significant quantities of trace elements into the atmosphere, which can infiltrate ecosystems through both wet and dry deposition, resulting in ecological harm. Although the current study focuses on the emission inventory and deposition of trace elements, their complex interactions remain insufficiently explored. In this study, we employ emission inventories and deposition data for eight TEs (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb) in Lanzhou City to unveil the relationship between these two aspects. Emissions in Lanzhou can be roughly divided into two periods centered around 2017. Preceding 2017, industrial production constituted the primary source of TEs emissions except for As; coal combustion was the primary contributor to Cr, Mn, and As emissions; waste incineration played a significant role in As, Zn, and Cd emissions; biomass combustion influenced Cr and Cd emissions; and transportation sources were the predominant contributors to Pb and Cu emissions. With the establishment of waste-to-energy plants and the implementation of ultra-low emission retrofits, emissions from these sources decreased substantially after 2017. Consequently, emissions from industrial production emerged as the main source of TEs. The deposition concentrations of Cr, Mn, Ni, Cu, and Pb followed a similar trend to the emissions. However, Cd and As exhibited lower emissions and a less pronounced response relationship. Moreover, Zn concentrations fluctuated within a narrow range and showed a weaker response to emissions. The consistent changes in emissions and TEs deposition concentrations signify a shift in deposition pollution in Lanzhou city from Coal-fired pollution to that driven by transportation and industrial activities. Within this transition, the industrial production process offers significant potential for emission reduction. This insight provides a crucial foundation for managing TEs pollution and implementing strategies to prevent ecological risks.