10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Overview of Fog Water Chemistry in Namibia during the AEROCLO-sA Campaign
Denise Napolitano, Stéphanie Rrossignol, Chiara Giorio, Roland Mushi, Gillian Maggs-Kölling, Barbara D'Anna, Bruno Coulomb, Jean-Luc Boudenne, Stuart J. Piketh, Andreas Namwoonde, Paola Formenti, Anne Monod, PIERRE HERCKES, Arizona State University
Abstract Number: 1424 Working Group: Clouds and Climate
Abstract Namibia is an arid country where many rural and urban centers depend on ephemeral rivers for their water supply. These water sources are, however, limited and display seasonal salinization. Fog occurs along the coast and extends for up to 100 km inland, and has been considered for a long time as a source of drinking water. Fog is also a vital source of moisture for the endemic flora and fauna of the Namib Desert. However, due to the current change in climate and air quality, fog occurrence and composition, of crucial importance for the local ecosystems and populations, may be impacted.
The AErosol RadiatiOn and CLOuds in southern Africa (AEROCLO-sA) project investigated the interactions between aerosols, clouds and radiation fog in the South East Atlantic off the western coast of southern Africa. Within this framework fog and aerosol samples were collected in Henties Bay (Namibia), right at the Atlantic Ocean during an intensive campaign in September 2017. Eight fog events were sampled with two Caltech Active Stand Cloud Water Collectors (CASCC) operated in parallel, one stainless steel collector for organic matter analysis and one plastic collector for inorganic species characterization.
Fog samples were analyzed for pH, major ions, trace metals and organic carbon content (TOC and DOC). In addition, the fog samples were characterized by aerosol mass spectrometry (AMS-c-TOF-MS) and by optical spectroscopy including UV-VIS and 3D fluorimetric analysis. The results of the study will be presented and discussed relative to chemical data on local seawater and aerosol samples. Sea spray has been identified as the major source of many chemical species in these fogs. These results will be contrasted with fog chemistry observations at a more inland site in Namibia at the Gobabeb Research and Training Center. Here the marine impact is less dominant for many species.