QUANTIFICAÇÃO DE GASES DE EFEITO ESTUFA EM ATERRO SANITÁRIO NO MUNICÍPIO DE CUIABÁ

<p>A disposição do lixo no Brasil, onde o uso de “lixões” ainda é muito comum, é um dos graves problemas ambientais. A emissão de gases produzidos pela decomposição anaeróbia da matéria orgânica pode ser uma ameaça ao ambiente local causando danos à vegetação, gerando odores desagradáveis, oferecendo ainda riscos de explosão. Este estudo objetivou avaliar as emissões de dióxido de carbono (CO₂) e metano (CH₄) no Aterro Sanitário no Município de Cuiabá, utilizando câmaras estáticas. Avaliou três pontos de amostragem com diferentes tempos de deposição de resíduos. Os valores anuais de CO₂ foram: no ponto A (deposição recente), 19,02 μg CO₂ m^-2 h^-1; no ponto B (deposição intermediária), 4,36 μg CO₂ m^-2 h^-1 e, no ponto C (deposição com maior tempo), 2,59 μg CO₂ m^-2 h^-1. A concentração de CH₄ no ponto A foi 3,89 μg CH₄ m^-2 h^-1 e 0,12 e 0,25 μg CH₄ m^-2 h^-1 nos pontos B e C, respectivamente. Os resultados de CO₂ e CH₄ tiveram comportamentos semelhantes, houve aumento das concentrações. O estudo concluiu que fluxo de gases é dependente do tempo de deposição de resíduos e que, de acordo com esse tempo de deposição, a compactação do solo atua como limitador na emissão de GEE.</p><p> </p><p align="center">QUANTIFICATION OF GREENHOUSE GASES IN LANDFILL IN CUIABÁ CITY</p><p>The disposal of garbage in Brazil is one of the serious environmental problems where the use of "dumps" is still very common. The emission of gases produced by the anaerobic decomposition of organic matter can be a threat to the local environment, causing damage to vegetation, generating unpleasant odors, also offering risks of explosion. This study objective evaluated emissions of Carbon Dioxide (CO₂) and Methane (CH₄) in landfill in the Cuiabá city, using static chambers. Three sampling points under different waste deposition times were evaluated. The annual flow of CO₂ at point A (recent deposition) was 19.02 μg CO₂ m^-2 h^-1, at point B (intermediate), it was 4.36 μg CO₂ m^-2 h^-1, and at point C (deposition with longer time) was 2.59 μg CO₂ m^-2 h^-1. The concentration of CH₄ at point A was 3.89 μg CH₄ m^-2 h^-and 0.12 and 0.25 μg CH₄ m^-2 h^-1respectively at points B and C. The results of CO₂ and CH₄, have similar behavior, occurring increase of concentrations. It concluded that gas flow is dependent on the time of waste deposition, and according to the time of deposition, the soil compaction performances as a limiting factor in GHG emissions.</p>

Detection of ammonia on Pluto’s surface in a region of geologically recent tectonism

We report the detection of ammonia (NH3) on Pluto’s surface in spectral images obtained with the New Horizons spacecraft that show absorption bands at 1.65 and 2.2 μm. The ammonia signature is spatially coincident with a region of past extensional tectonic activity (Virgil Fossae) where the presence of H2O ice is prominent. Ammonia in liquid water profoundly depresses the freezing point of the mixture. Ammoniated ices are believed to be geologically short lived when irradiated with ultraviolet photons or charged particles. Thus, the presence of NH3 on a planetary surface is indicative of a relatively recent deposition or possibly through exposure by some geological process. In the present case, the areal distribution is more suggestive of cryovolcanic emplacement, however, adding to the evidence for ongoing geological activity on Pluto and the possible presence of liquid water at depth today.

Optical dating of late Quaternary carbonate sequences of Saurashtra, western India

Bioclastic carbonate deposits that formed because of a combination of nearshore marine, fluvial, and aeolian processes, occur along the Saurashtra coast and in the adjacent interior regions of western India. Whether these carbonates formed by marine or aeolian processes has been debated for many decades. The presence of these deposits inland poses questions as to whether they are climate controlled or attributable to postdepositional tectonic uplift. In particular, the debate centres on chronologic issues including (1) appropriate sampling strategies and (2) the use of 230Th/234U and 14C ages on the bulk carbonates. Using traces (<1%) of quartz grains trapped in carbonate matrices, optically stimulated luminescence (OSL) dating of quartz grains, deposited along with the carbonate grains, provides ages for the most recent deposition events. The OSL ages range from >165 to 44 ka for the shell limestones, 75–17 ka for the fluvially reworked sheet deposits, and 80–11 ka for miliolites deposited by aeolian processes. These are younger than the 230Th/234U and 14C ages and suggest that the inland carbonate deposits were reworked from older carbonate sediments that were transported during more arid phases.

Direct Numerical Simulations of Electrophoretic Deposition of Charged Colloidal Suspensions

Motivated by applications in the field of nanomanufacturing, we perform large-scale numerical simulations of the electrophoretic deposition of suspensions of charged colloids in an electrolyte. A simulation method is developed to model the full deposition process that captures linear electrophoresis, dipolar interactions, van-der-Waals forces, steric interactions, Brownian motion, as well as electric and hydrodynamic interactions with the electrodes. Using a fast algorithm, suspensions of up to 5,000 particles are simulated, and results are reported for the final deposit microstructure as a function of field strength. The simulation results demonstrate that regular crystalline colloidal assemblies are obtained at low field strengths and volume fractions, while more random structures with frequent defects are formed in stronger fields and at higher volume fractions, in agreement with recent deposition experiments.