Dependence of Daily Aerosol Wet Deposition on Precipitation at Appalachian Mountains Site in the United States

Abstract

The wet removal of airborne particulates is a significant component of atmospheric deposition in the Eastern United States. This study analyzed the daily wet deposition of major ions at the Canaan Valley site in Appalachian Mountains in Eastern US, for the time interval 2000-2014. The site is part of the Atmospheric Integrated Research Monitoring Network (AIRMoN), and is significantly impacted by acid precipitation, caused largely by anthropogenic sources of SO 2 and NO x . Results show that the precipitation rate, R, varies mainly in the interval [0.01-100] mm day -1 , and the daily wet deposition flux, F, varies about two orders of magnitude for most ions. The largest daily wet depositions are for SO 4 2-and NO 3 -with extreme values over 30 mg m -2 day -1 . In the case of NH 4 + , the largest daily wet depositions are over 10 mg m -2 day -1 . Seasonal variations are illustrated by contrasting the winter and summer. In general, there are much larger daily wet deposition fluxes in summer than in winter. For SO 4 2-there is more conversion of SO 2 to SO 4 2-in the gas phase and in cloud droplets during summer. Similarly, NH 4 + has a distinct seasonal variation with a maximum in summer, consistent with larger sources of NH 3 during the growth season. NO 3 -has a maximum concentration in precipitation during winter, and a maximum daily wet deposition flux during summer, especially during the most intense rain events. The Na + and Clions have the highest wet deposition in winter due to storms that bring air masses from Atlantic. Analysis shows that precipitation events are more frequent and more intense in summer than in winter. For the Canaan Valley, the summer precipitation events are effective in wet removal of aerosols providing episodes with some of the highest rates of acid deposition.

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Avaliação de qualidade de água de chuva de telhados verdes para usos não potáveis

“…Com o aumento de atividades antrópicas, há também o aumento de emissões de poluentes na atmosfera, alterando a concentração dos elementos, e essa alteração pode ocasionar o efeito de deposição úmida, ou seja, o arraste de elementos da atmosfera através do contato com gotículas precipitadas (ANDRONACHE, 2016).…”

“…Dessa forma, no evento da precipitação, as gotas podem ter contato com elementos presentes na atmosfera e sofrer alteração na concentração desse elemento (MARTINS et al, 2019). Após a água entrar em contato com a superfície em que houve a deposição de partículas da atmosfera, ela pode sofrer outra alteração da concentração (ANDRONACHE, 2016).…”