scholarly journals Characterization of aerosol particles at Cabo Verde close to sea level and at the cloud level – Part 2: Ice-nucleating particles in air, cloud and seawater

2020 ◽  
Vol 20 (3) ◽  
pp. 1451-1468 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Manuela van Pinxteren ◽  
Nadja Triesch ◽  
Khanneh Wadinga Fomba ◽  
...  
Keyword(s):  
Sea Level ◽  
Cloud Water ◽  
Ice Nucleation ◽  
Cape Verde ◽  
Nucleation Temperature ◽  
Sea Spray ◽  
Cloud Droplets ◽  
Cabo Verde ◽  
Active Particles ◽  
Sea Surface Microlayer

Abstract. Ice-nucleating particles (INPs) in the troposphere can form ice in clouds via heterogeneous ice nucleation. Yet, atmospheric number concentrations of INPs (NINP) are not well characterized, and, although there is some understanding of their sources, it is still unclear to what extend different sources contribute or if all sources are known. In this work, we examined properties of INPs at Cabo Verde (a.k.a. Cape Verde) from different environmental compartments: the oceanic sea surface microlayer (SML), underlying water (ULW), cloud water and the atmosphere close to both sea level and cloud level. Both enrichment and depletion of NINP in SML compared to ULW were observed. The enrichment factor (EF) varied from roughly 0.4 to 11, and there was no clear trend in EF with ice-nucleation temperature. NINP values in PM10 sampled at Cape Verde Atmospheric Observatory (CVAO) at any particular ice-nucleation temperature spanned around 1 order of magnitude below −15 ∘C, and about 2 orders of magnitude at warmer temperatures (>-12 ∘C). Among the 17 PM10 samples at CVAO, three PM10 filters showed elevated NINP at warm temperatures, e.g., above 0.01 L−1 at −10 ∘C. After heating samples at 95 ∘C for 1 h, the elevated NINP at the warm temperatures disappeared, indicating that these highly ice active INPs were most likely biological particles. INP number concentrations in PM1 were generally lower than those in PM10 at CVAO. About 83±22 %, 67±18 % and 77±14 % (median±standard deviation) of INPs had a diameter >1 µm at ice-nucleation temperatures of −12, −15 and −18 ∘C, respectively. PM1 at CVAO did not show such elevated NINP at warm temperatures. Consequently, the difference in NINP between PM1 and PM10 at CVAO suggests that biological ice-active particles were present in the supermicron size range. NINP in PM10 at CVAO was found to be similar to that on Monte Verde (MV, at 744 m a.s.l.) during noncloud events. During cloud events, most INPs on MV were activated to cloud droplets. When highly ice active particles were present in PM10 filters at CVAO, they were not observed in PM10 filters on MV but in cloud water samples instead. This is direct evidence that these INPs, which are likely biological, are activated to cloud droplets during cloud events. For the observed air masses, atmospheric NINP values in air fit well to the concentrations observed in cloud water. When comparing concentrations of both sea salt and INPs in both seawater and PM10 filters, it can be concluded that sea spray aerosol (SSA) only contributed a minor fraction to the atmospheric NINP. This latter conclusion still holds when accounting for an enrichment of organic carbon in supermicron particles during sea spray generation as reported in literature.

scholarly journals Characterization of aerosol particles at Cape Verde close to sea and cloud level heights – Part 2: ice nucleating particles in air, cloud and seawater

2019 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Manuela van Pinxteren ◽  
Nadja Triesch ◽  
Khanneh Wadinga Fomba ◽  
...  
Keyword(s):  
Cloud Water ◽  
Cape Verde ◽  
Surface Microlayer ◽  
Cloud Droplets ◽  
Clear Trend ◽  
Cold Temperatures ◽  
Biological Particles ◽  
Active Particles ◽  
Sea Surface Microlayer ◽  
Different Sources

Abstract. Ice nucleating particles (INPs) in the troposphere can form ice in clouds via heterogeneous ice nucleation. Yet, atmospheric number concentrations of INPs (NINP) are not well characterized and although there is some understanding of their sources, it is still unclear to what extend different sources contribute, nor if all sources are known. In this work, we examined properties of INPs at Cape Verde from different sources, the oceanic sea surface microlayer (SML) and underlying water (ULW), the atmosphere close to both sea and cloud level as well as cloud water. Both enrichment and depletion of NINP in SML compared to ULW were observed. The enrichment factor (EF) varied from roughly 0.4 to 11, and there was no clear trend in EF with temperature. NINP in PM10 sampled at Cape Verde Atmospheric Observatory (CVAO) at any particular temperature spanned around 1 order of magnitude below −15 °C, and about 2 orders of magnitude at warmer temperatures (>−12 °C). NINP in PM1 were generally lower than those in PM10 at CVAO. About 83 ± 22 %, 67 ± 18 % and 77 ± 14 % (median ± standard deviation) of INPs had a diameter > 1 µm at ice activation temperatures of −12, −15, and −18 °C, respectively. Among the 17 PM10 samples at CVAO, three PM10 filters showed elevated NINP at warm temperatures, e.g., above 0.01 std L−1 at −10 °C. However, for NINP in PM1 at CVAO, this is not the case. At these higher temperatures, often biological particles have been found to be ice active. Consequently, the difference in NINP between PM1 and PM10 at CVAO, suggests that biological ice active particles were present in the super-micron size range. NINP in PM10 at CVAO was found to be similar to that on Monte Verde (MV, at 744 m a.s.l.) during non-cloud events. During cloud events, most INPs on MV were activated to cloud droplets. When highly ice active particles were present in PM10 filters at CVAO, they were not observed in PM10 filters on MV, but in cloud water samples, instead. This is direct evidence that these INPs which are likely biological are activated to cloud droplets during cloud events. In general, Cape Verde was often affected by dust from the Saharan desert during our measurement. For the observed air masses, atmospheric NINP in air fit well to the concentrations observed in cloud water. When comparing concentrations of both sea salt and INPs in both seawater and PM10 filters, it can be concluded that sea spray aerosol (SSA) only contributed a minor fraction to the atmospheric NINP. Therefore it can be said that, unless there would be a significant enrichment of NINP during the formation of SSA particles, NINP was mainly dominated by mineral dust at cold temperatures with few contributions from possible biological particles at warmer temperatures.

scholarly journals The ice-nucleating activity of Arctic sea surface microlayer samples and marine algal cultures

2020 ◽  
Vol 20 (18) ◽  
pp. 11089-11117 ◽  
Author(s):  
Luisa Ickes ◽  
Grace C. E. Porter ◽  
Robert Wagner ◽  
Michael P. Adams ◽  
Sascha Bierbauer ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
Sea Surface ◽  
The Arctic ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Phytoplankton Species ◽  
Sea Surface Microlayer ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Algal Cultures

Abstract. In recent years, sea spray as well as the biological material it contains has received increased attention as a source of ice-nucleating particles (INPs). Such INPs may play a role in remote marine regions, where other sources of INPs are scarce or absent. In the Arctic, these INPs can influence water–ice partitioning in low-level clouds and thereby the cloud lifetime, with consequences for the surface energy budget, sea ice formation and melt, and climate. Marine aerosol is of a diverse nature, so identifying sources of INPs is challenging. One fraction of marine bioaerosol (phytoplankton and their exudates) has been a particular focus of marine INP research. In our study we attempt to address three main questions. Firstly, we compare the ice-nucleating ability of two common phytoplankton species with Arctic seawater microlayer samples using the same instrumentation to see if these phytoplankton species produce ice-nucleating material with sufficient activity to account for the ice nucleation observed in Arctic microlayer samples. We present the first measurements of the ice-nucleating ability of two predominant phytoplankton species: Melosira arctica, a common Arctic diatom species, and Skeletonema marinoi, a ubiquitous diatom species across oceans worldwide. To determine the potential effect of nutrient conditions and characteristics of the algal culture, such as the amount of organic carbon associated with algal cells, on the ice nucleation activity, Skeletonema marinoi was grown under different nutrient regimes. From comparison of the ice nucleation data of the algal cultures to those obtained from a range of sea surface microlayer (SML) samples obtained during three different field expeditions to the Arctic (ACCACIA, NETCARE, and ASCOS), we found that they were not as ice active as the investigated microlayer samples, although these diatoms do produce ice-nucleating material. Secondly, to improve our understanding of local Arctic marine sources as atmospheric INPs we applied two aerosolization techniques to analyse the ice-nucleating ability of aerosolized microlayer and algal samples. The aerosols were generated either by direct nebulization of the undiluted bulk solutions or by the addition of the samples to a sea spray simulation chamber filled with artificial seawater. The latter method generates aerosol particles using a plunging jet to mimic the process of oceanic wave breaking. We observed that the aerosols produced using this approach can be ice active, indicating that the ice-nucleating material in seawater can indeed transfer to the aerosol phase. Thirdly, we attempted to measure ice nucleation activity across the entire temperature range relevant for mixed-phase clouds using a suite of ice nucleation measurement techniques – an expansion cloud chamber, a continuous-flow diffusion chamber, and a cold stage. In order to compare the measurements made using the different instruments, we have normalized the data in relation to the mass of salt present in the nascent sea spray aerosol. At temperatures above 248 K some of the SML samples were very effective at nucleating ice, but there was substantial variability between the different samples. In contrast, there was much less variability between samples below 248 K. We discuss our results in the context of aerosol–cloud interactions in the Arctic with a focus on furthering our understanding of which INP types may be important in the Arctic atmosphere.

scholarly journals Marine organic matter in the remote environment of the Cape Verde Islands – An introduction and overview to the MarParCloud campaign

2020 ◽  
Author(s):  
Manuela van Pinxteren ◽  
Khanneh Wadinga Fomba ◽  
Nadja Triesch ◽  
Heike Wex ◽  
Xianda Gong ◽  
...  
Keyword(s):  
Organic Matter ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Cape Verde ◽  
Back Trajectory ◽  
Surface Microlayer ◽  
Mercury Species ◽  
Biological Production ◽  
Cell Counts ◽  
Sea Surface Microlayer

<p>The project MarParCloud (marine biological production, organic aerosol particles and marine clouds: a process chain) aims at achieving a better understanding of the biological production of organic matter (OM)in the oceans, its export into marine aerosol particles and finally its ability to act as ice and cloud condensation nuclei (INP and CCN). The core of MarParCloud comprised a field campaign at the Cape Verde Atmosphere Observatory (CVAO) in autumn 2017, where a variety of chemical, physical, biological and meteorological approaches were applied. The investigations included concerted measurements of the bulk water, the Sea Surface Microlayer (SML), ambient aerosol particles on the ground (30 m a.s.l.) and in mountain heights (744 m) as well as cloud water. Important aspects of the ocean atmosphere Interactions focusing on marine OM have been addressed through detailed observation and modeling approaches.</p><p>Key variables comprised the chemical characterization of the atmospherically relevant OM components (e.g. lipids, proteins, sugars) in the ocean and the atmosphere as well as measurements of INP and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analysed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modelling studies supported the experimental analysis.</p><p>Here we show the proof of concept of the connection between organic matter emission from the ocean to the atmosphere and up to the cloud level. A link between the ocean and the atmosphere was clearly observed as (i) the particles measured at the surface are well mixed within the marine boundary layer up to cloud level and (ii) ocean-derived compounds can be found in the aerosol particles at mountain height and in the cloud water. The organic measurements will be implemented in a new source function for the oceanic emission of OM. However, from a perspective of particle number concentrations, the marine contributions to both CCN and INP are rather limited.</p>

scholarly journals Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

2021 ◽  
Vol 21 (18) ◽  
pp. 13903-13930
Author(s):  
Robert Wagner ◽  
Luisa Ickes ◽  
Allan K. Bertram ◽  
Nora Els ◽  
Elena Gorokhova ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Surface ◽  
Ice Formation ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Seawater Samples ◽  
Heterogeneous Ice Nucleation

Abstract. Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea spray aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235 K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5×1010 m−2 at an ice saturation ratio of 1.3. Much smaller densities in the range of 108–109 m−2 were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are 2 orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the number of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how instrumental parameters like the aerosolisation method and the ice nucleation measurement technique might affect the comparability of the results amongst different studies.

scholarly journals Characterization of aerosol particles at Cabo Verde close to sea level and at the cloud level – Part 1: Particle number size distribution, cloud condensation nuclei and their origins

2020 ◽  
Vol 20 (3) ◽  
pp. 1431-1449 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Jens Voigtländer ◽  
Khanneh Wadinga Fomba ◽  
Kay Weinhold ◽  
...  
Keyword(s):  
Size Distribution ◽  
Sea Level ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Cape Verde ◽  
Sea Spray ◽  
Particle Number Concentration ◽  
Air Masses

Abstract. In the framework of the MarParCloud (Marine biological production, organic aerosol particles and marine clouds: a Process Chain) project, measurements were carried out on the islands of Cabo Verde (a.k.a. Cape Verde) to investigate the abundance, properties and sources of aerosol particles in general, and cloud condensation nuclei (CCN) in particular, both close to sea level and at the cloud level. A thorough comparison of particle number concentration (PNC), particle number size distribution (PNSD) and CCN number concentration (NCCN) at the Cape Verde Atmospheric Observatory (CVAO, sea-level station) and Monte Verde (MV, cloud-level station) reveals that during times without clouds the aerosols at CVAO and MV are similar and the boundary layer is generally well mixed. Therefore, data obtained at CVAO can be used to describe the aerosol particles at cloud level. Cloud events were observed at MV during roughly 58 % of the time, and during these events a large fraction of particles was activated to cloud droplets. A trimodal parameterization method was deployed to characterize PNC at CVAO. Based on number concentrations in different aerosol modes, four well-separable types of PNSDs were found, which were named the marine type, mixture type, dust type1 and dust type2. Aerosol particles differ depending on their origins. When the air masses came from the Atlantic Ocean, sea spray can be assumed to be one source for particles besides new particle formation. For these air masses, PNSDs featured the lowest number concentration in Aitken, accumulation and coarse modes. Particle number concentrations for sea spray aerosol (SSA, i.e., the coarse mode for these air masses) accounted for about 3.7 % of NCCN,0.30 % (CCN number concentration at 0.30 % supersaturation) and about 1.1 % to 4.4 % of Ntotal (total particle number concentration). When the air masses came from the Sahara, we observed enhanced Aitken, accumulation and coarse mode particle number concentrations and overall increased NCCN; NCCN,0.30 % during the strongest observed dust periods is about 2.5 times higher than that during marine periods. However, the particle hygroscopicity parameter κ for these two most different periods shows no significant difference and is generally similar, independent of air mass. Overall, κ averaged 0.28, suggesting the presence of organic material in particles. This is consistent with previous model work and field measurements. There is a slight increase in κ with increasing particle size, indicating the addition of soluble, likely inorganic, material during cloud processing.

scholarly journals Arctic marine ice nucleating aerosol: a laboratory study of microlayer samples and algal cultures

2020 ◽  
Author(s):  
Luisa Ickes ◽  
Grace C. E. Porter ◽  
Robert Wagner ◽  
Michael P. Adams ◽  
Sascha Bierbauer ◽  
...  
Keyword(s):  
Ice Nucleation ◽  
The Arctic ◽  
Sea Spray ◽  
Phytoplankton Species ◽  
Diatom Species ◽  
Sea Surface Microlayer ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Skeletonema Marinoi ◽  
Algal Cultures

Abstract. In recent years, sea spray and the biological material it contains has received increased attention as a source of ice nucleating particles (INPs). Such INPs may play a role in remote marine regions, where other sources of INPs are scarce or absent. Marine aerosol is of diverse nature, so identifying sources of INPs is challenging. One fraction of marine bioaerosol, phytoplankton and their exudates, has been a particular focus of marine INP research. In our study we attempt to address three main questions. Firstly, we compare the ice nucleating ability of two common phytoplankton species with Arctic seawater microlayer samples using the same instrumentation to see if these phytoplankton species produce ice nucleating material with sufficient activity to account for the ice nucleation observed in Arctic microlayer samples. We present first measurements of the ice nucleating ability of two predominant phytoplankton species, Melosira arctica, a common Arctic diatom species and Skeletonema marinoi, a ubiquitous diatom species across oceans worldwide. To determine the potential effect of nutrient conditions and characteristics of the algal culture, such as the amount of organic carbon associated with algal cells, on the ice nucleation activity, the Skeletonema marinoi was grown under different nutrient regimes. From comparison of the ice nucleation data of the algal cultures to those obtained from a range of sea surface microlayer (SML) samples obtained during three different field expeditions to the Arctic (ACCACIA, NETCARE, ASCOS) we found that although these diatoms do produce ice nucleating material, they were not as ice active as the investigated microlayer samples. Secondly, to improve our understanding of local Arctic marine sources as atmospheric INP we applied several aerosolisation techniques to analyse the ice nucleating ability of aerosolised microlayer and algae samples. The aerosols were generated either by direct nebulisation of the undiluted bulk solutions, or by the addition of the samples to a sea spray simulation chamber filled with artificial seawater. The latter method generates aerosol particles using a plunging jet to mimic the process of oceanic wave-breaking. We observed that the aerosols produced using this approach can be ice active indicating that the ice nucleating material in seawater can indeed transfer to the aerosol phase. Thirdly, we attempted to measure ice nucleation activity across the entire temperature range relevant for mixed-phase clouds using a suite of ice nucleation measurement techniques- an expansion cloud chamber, a continuous flow diffusion chamber, and a cold stage. In order to compare the measurements made using the different instruments, we have normalised the data in relation to the mass of salt present in the nascent sea spray aerosol. At temperatures above 248 K some of the SML samples were very effective at nucleating ice, but there was substantial variability between the different samples. In contrast, there was much less variability between samples below 248 K.

scholarly journals Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

2021 ◽  
Author(s):  
Robert Wagner ◽  
Luisa Ickes ◽  
Allan K. Bertram ◽  
Nora Els ◽  
Elena Gorokhova ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Surface ◽  
Ice Formation ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Seawater Samples ◽  
Heterogeneous Ice Nucleation

Abstract. Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea salt aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235 K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in a large cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5·1010 m−2 at an ice saturation ratio of 1.3. Much smaller densities in the range of 108–109 m−2 were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are two orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the amount of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how far instrumental parameters like the aerosolisation method and the ice-nucleation measurement technique might affect the comparability of the results amongst different studies.

scholarly journals The phantasmatic logic of e-government and the discourse of innovation in Cape Verde

2020 ◽  
Vol 54 (2) ◽  
pp. 266-284
Author(s):  
Osíris Luís da Cunha Fernandes ◽  
Fernando Gomes de Paiva Júnior ◽  
Nelson da Cruz Monteiro Fernandes ◽  
Marconi Freitas da Costa
Keyword(s):  
Cape Verde ◽  
Cabo Verde ◽  
Ernesto Laclau ◽  
Chantal Mouffe

Resumo O objetivo deste estudo consiste em aprofundar as reflexões sobre o e-government (e-gov) a partir de uma análise do campo discursivo da inovação no setor público em Cabo Verde, sob a ótica da Teoria do Discurso (TD) de Ernesto Laclau e Chantal Mouffe. Para tanto, por meio de estudo de caso instrumental e usando o método da retrodução proposto por Jason Glynos e David Howarth e a análise do discurso (de matriz francesa) dos sujeitos que constituíram o e-gov, buscamos desvelar a lógica fantasmática da articulação discursiva dessa prática social. Os resultados mostram, por um lado, que, embora, o e-gov seja uma entidade incompleta, vulnerável e contingente, a identidade dos agentes envolvidos em sua articulação discursiva depende de sua capacidade de reiterar os discursos de “aposta na sociedade da informação”, “e-government como opção estratégica para o desenvolvimento” e “reforma do Estado e modernização administrativa” ao longo do tempo. Por outro lado, o e-gov se revelou um sistema discursivo impregnado de demandas relacionadas a um tecnicismo ocasional e à crença implícita dos agentes do setor público cabo-verdiano de que o uso das tecnologias de informação e comunicação (TIC) pelas instituições públicas gera avanços estruturadores na modernização administrativa e na transformação social.

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