Caring about the future

CV-Dust - Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport
Coordinator - Casimiro Pio
Programme - PTDC/AAC-CLI/100331/2008
Execution dates - 2010-05-01 - 2013-04-30 (36 Months)
Funding Entity - FCT; COMPETE
Funding for CESAM - 130686 €
Total Funding - 198891 €
Proponent Institution - Universidade de Aveiro
Participating Institutions
Universidade de Aveiro (CESAM and GEOBIOTEC)
Instituto Tecnológico e Nuclear

Project Description

Every year, billions of tons of eroded mineral soils are carried from the Saharan Desert and the Sahel to America, Caribbean and Europe. Saharan dust has been transported across the Atlantic for millions of years, depositing nutrients to the East Mediterranean[1], red-clay soils to the limestone islands of the Caribbean[2], freshwater diatoms and phytoliths in the tropical and equatorial Atlantic[3], and iron that periodically triggers red-tides in the Gulf of Mexico[4]. Dust optical parameters, size and spatial distribution of mineral aerosols determine the direct interaction of solar and terrestrial radiation in the atmosphere through scattering and absorption[5]. Mineral dust also has a great impact on cloud formation including both ice and water clouds leading to additional indirect radiation effects. In addition, the bulk and surface chemistry of the mineral dust particles determines interactions with gaseous and other particle species. The global importance of desert dust with regard to the impact on the direct radiative forcing and its possible effect on the indirect radiative forcing was emphasized within the IPCC Report[6]. However, quantification of the magnitude of warming or cooling remains open because of the strong variability of the atmospheric dust burden and the lack of representative data for the spatial and temporal distribution of the dust composition. A detailed data on the size distribution and the size-resolved chemical and mineralogical composition of dust providing from Africa is fundamental 1) to understand processes governing production, transport and removal from the atmosphere; 2) to estimate the global importance of these particles on the radiative forcing and to quantify the magnitude of the warming or cooling; 3) to understand the impact of mineral aerosols on the marine organisms and the role of dust-borne iron on the ocean carbon cycle (and, hence, on atmospheric CO2) and 4) to comprehend the impact of dust in the human health and wellbeing. Cape Verde is located in an area of massive dust transport from land to ocean, and is thus ideal to set up sampling devices that will able the characterization and the quantification of the dust transported from Africa. Moreover, Cape Verde´s future economic prospects depend heavily on the encouragement of tourism, therefore it is essential to elucidate the role of Saharan dust may play in the degradation of Cape Verde air quality. Therefore, the main objectives of CV-Dust project are: 1) to characterize the chemical and mineralogical composition of dust transported from Africa by setting up an orchestra of aerosol sampling devices in the strategic archipelago of Cape Verde; 2) to identify the sources of particles in Cape Verde by using receptor models; 3) to elucidate the role Saharan dust may play in the degradation of Cape Verde air quality; 4) to model processes governing dust production, transport, interaction with the radiation field and removal from the atmosphere. Aerosol sampling will be performed during one year and chemical characterization of the particles will be performed by Neutron Activation Analysis for elemental measurements, Ion Chromatography for the determination of water soluble ions, a thermo-optical system for the determination of Black and Organic Carbon and CO2 evolution – NDIR for carbonates. Mineralogical composition will be studied by X-ray diffraction, TEM and Scanning electron microscopy. The identification of the main sources and origins of the particles sampled in the archipelago will be carried out by integrating complementary tools including Principal Component Analysis, Positive Matrix Factorization, Chemical Mass Balance, Multilinear Regression Analysis, Air Mass Back trajectories analyses, meteorological data and particle size segregate analysis. Temporal and spatial distribution of air pollutants concentrations will be provided by a system of transport models. Satellite observations will be used for an integrated analysis and interpretation of the modeling results. The project is a joint initiative of Aveiro University (UA) and Technological and Nuclear Institute (ITN), together with the Cape Verde University (Uni-CV) and the support of the Cape Verde Atmospheric Observatory (CVAO). CVAO is part of a bilateral German-UK initiative to undertake long-term ground- and ocean-based observations in the tropical Eastern North Atlantic Ocean region. It links with the international programme SOLAS, the EU-funded TENATSO (Tropical Eastern North Atlantic Time-Series Observatory) project and with the German SOPRAN (Surface Ocean Processes in the Anthropocene) project. UA and ITN are widely recognized as centres of excellence in aerosol research.Over the last two decades, UA and ITN have developed aerosol sampling and analysis instrumentation and modeling tools, which nowadays are applied successfully in several aerosol studies.

Project webpage

CESAM members on this project
Casimiro Pio

Joana Ferreira
Teresa Nunes

CESAM Funding: UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020