RESUMEN
Low-cost PM2.5 sensors are now used worldwide to assess air pollution. However, their operation is generally challenging in severely cold regions like Siberia, Alaska, the Arctic, and Antarctica. We made an insulation box with automatic internal temperature control developed for a low-cost PM2.5 sensor to maintain a warm operational environment with four light-bulb heaters when the air temperature inside of the insulation box falls slightly below 5 °C under the current preset temperature setting. We confirmed the performance of the temperature controller with four light-bulb heaters in a -25 °C cold temperature room. In addition, we found that the insulation box must be attached to a small electric fan to forcibly ventilate the box to accurately reflect the external ambient air conditions into the insulating box. Our observations with the data from our low-cost PM2.5 sensor fitted with the insulation box were validated against the Sapporo National Ambient Air Monitoring Station (NAAMS) data in Sapporo, Japan, showing good correspondence with the hourly station-measured data. Then, we installed our PM2.5 measurement system on the roof of the International Arctic Research Center (IARC), University of Alaska Fairbanks, Alaska, USA, in June 2019. The sensor sufficiently captured two instances of significant increases in PM2.5 mass concentrations during the Alaskan wildfires in the summer of 2019. Our developed insulation box for low-cost PM2.5 sensors, called "the portable PM2.5 measurement system for cold regions", will help assess air quality in many cold regions in future studies.
RESUMEN
After the 1980s, atmospheric sulfate reduction is slower than the dramatic reductions in sulfur dioxide (SO2) emissions. However, a lack of observational evidence has hindered the identification of causal feedback mechanisms. Here, we report an increase in the oxygen isotopic composition of sulfate ([Formula: see text]) in a Greenland ice core, implying an enhanced role of acidity-dependent in-cloud oxidation by ozone (up to 17 to 27%) in sulfate production since the 1960s. A global chemical transport model reproduces the magnitude of the increase in observed [Formula: see text] with a 10 to 15% enhancement in the conversion efficiency from SO2 to sulfate in Eastern North America and Western Europe. With an expected continued decrease in atmospheric acidity, this feedback will continue in the future and partially hinder air quality improvements.
RESUMEN
Atmospheric sea-salt and halogen cycles play important roles in atmospheric science and chemistry including cloud processes and oxidation capacity in the Antarctic troposphere. This paper presents a review and summarizes current knowledge related to sea-salt and halogen chemistry in the Antarctic. First, presented are the seasonal variations and size distribution of sea-salt aerosols (SSAs). Second, SSA origins and sea-salt fractionation on sea-ice and ice sheets on the Antarctic continent are presented and discussed. Third, we discuss SSA release from the cryosphere. Fourth, we present SSA dispersion in the Antarctic troposphere and transport into inland areas. Fifth, heterogeneous reactions on SSAs as a source of reactive halogen species and their relationship with atmospheric chemistry are shown and discussed. Finally, we attempt to propose an outlook for obtaining better knowledge related to sea-salt and halogen chemistry and their effects on the Antarctic and the Arctic.
