Radiação gama e resistividade elétrica em solo com aplicação de carbonatito e fertilizantes agrícolas no Distrito Federal

A Embrapa Cerrados e a Universidade de Brasília desenvolveram um projeto que estudou a viabilidade da aplicação de carbonatito como fertilizante agrícola. Como experimento piloto, utilizaram-se diferentes misturas de carbonatito, calcário, superfosfato triplo (SFT) e cloreto de potássio (KCl) como fertilizantes em uma área de latossolo vermelho, na região central do Distrito Federal. Esta área foi dividida em 56 parcelas medindo 4 × 7m nas quais foram adicionadas as misturas de fertilizantes. Este trabalho teve por objetivo verificar se a adição das misturas ao solo modificou suas características radiométricas e de resistividade e se é possível identificar esta mudança. Realizaram-se medições da radiação gama e de resistividade elétrica na área do experimento e em uma área de cerrado nativo. Os resultados mostraram que a adição dos fertilizantes ao solo causou uma pequena elevação dos teores de K, U e Th e diminuiu cerca de dez vezes os valores de resistividade elétrica. Observou-se um baixo contraste radiométrico entre as parcelas que compõem o experimento, de modo que não foi possível diferenciar os vários tratamentos com base nas medidas gamaespectrométricas. A resistividade elétrica mostrou-se capaz de individualizar três grupos de parcelas em relação às características das misturas adicionadas, respectivamente com predomínio de SFT, de KCl e da mistura exclusiva de calcário e carbonatito.EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) and Brasília University developed a research project about the viability of carbonatite rock as agricultural fertilizer. As an initial experiment, several mixtures of carbonatite, limestone, phosphorous and potassium compounds were added as fertilizers in an oxisol area (red-latosol, according with Brazilian System of Soil Classification), in Distrito Federal, central Brazil. The experiment area was divided in 56 plots (4 × 7m) and each plot received a fertilizer mixture. The purpose of this work was to verify if the addition of fertilizer mixture to the soil modified its radiometric and resistivity properties and if it is possible to identify this change. Gamma-ray and electrical resistivity measurements were obtained in an experimental area and in a natural savannah type vegetation area. The results showed that the fertilizer addition modified soil natural properties causing a small increase in K, U, Th levels and decreasing ten times electrical resistivity. A low contrast of radiation was observed between plots, and then it was not possible to differentiate the several treatments in base of gamma-ray measurements. Electrical resistivity was efficient to identify three groups of plots related to mixtures characteristics, respectively with phosphorous, potassium and limestone / carbonatite predominance

Gamaespectrometria aplicada em solo agrícola no noroeste do Estado do Rio de Janeiro

O escopo deste trabalho consistiu no levantamento, processamento e interpretação dos dados de gamaespectrometria terrestre numa área utilizada para cultivo agrícola. Os dados observados indicam a perda de radioelementos dos solos em relação às rochas dos quais são oriundos. A comparação entre medidas em rocha e solos no levantamento terrestre aponta, para estes últimos, uma redução de cerca de 20% dos elementos urânio e tório, e cerca de 10% para o potássio. O menor percentual de perda para o potássio é associado, no presente trabalho, ao suprimento deste elemento no processo de fertilização química utilizada na área de estudo.Os resultados aqui obtidos apontam para uma adequação do uso deste método geofísico à identificação e ao monitoramento de áreas agrícolas no noroeste do Estado do Rio de Janeiro.The present work presents the use of gamma-ray spectrometry applied to precision agriculture in a sub-tropical area. Our dataset comprises measurements both in rock and residual soil. The soil dataset shows a reduction of 20% on U and Th and 10% on K, when compared to rock samples. This difference could be related to K supplementation associated to chemical fertilization

Geochemical and Geophysical Study in a Degraded Area Used for Disposal of Sludge from a Water Treatment Plant

The effects of disposal of sludge from water treatment plant (WTS) in area damaged by laterite extraction and its consequences to soil and groundwater were investigated. Therefore, the presence and concentration of anthropogenic elements and chemical compounds were determinated. WTS disposal's influence was characterized by electroresistivity method. The WTS's geochemical dispersion was noticed in the first meters of the nonsaturated zone from the lending area. Lateritic profiles were characterized due to the large variation in chemical composition between the horizons. Infiltration and percolation of rainwater through the WTS have caused migration of total dissolved solids to the groundwater. WTS's disposing area has more similarities to local preserved vegetation than to gravel bed area. WTS can be considered a noninert residue if disposed in degraded areas located in regions with similar geological and hydrochemical characteristics

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Visualização da propagação da umidade no solo por meio de eletrorresistividade

The DC electrical resistivity geophysical method is fairly used in geological and groundwater studies, as well as environmental monitoring activities. The purpose of electrical surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface. Electrical resistivity is mainly influenced by soil moisture and, in this work, moisture is the main soil property that is being studied. The field technique used was horizontal electrical profiling with Wenner arrangement for electrodes which is characterized by the equidistant disposal of potential and current electrodes, according to a straight line. The objective of this study is to demonstrate how is possible to visualize the progress of soil moisture through electrical resistivity data. Measurements were obtained using a resistivity meter with 25 electrodes connected to a multi-core cable in a 2-D electrical imaging survey. The Res2dinv software allowed the construction of four geoelectrical sections. The sections allowed the visualization of the progress of water plume, and demonstrated a progressive increase in soil moisture, related to the low resistivity area. These results demonstrated the applicability of this method for visualization of the soil moisture advance in a four hours period. 350 liters of clean water were used in this work, which was conducted in the region of Planaltina, Distrito Federal on the campus of the Brasilia University.Pages: 9293-929

Espectrometria de raios gama em metassedimentos e rochas gnáissicas na região de Cavalcante, Goiás

In this work, airborne gamma-ray spectrometry and digital elevation modeling were used for geological mapping. The integration of the geophysical and elevation data, using a statistical procedure, the cluster analysis, allowed to produce maps of statistical groups that have a good correlation with the geological units of Cavalcante - Goiás area, in the Middle-West of Brazil. In the study area, paleoproterozoic granite-gneiss basement and two proterozoic sedimentary units, Araí and Paranoá Groups, are founded. Shuttle Radar Topography Mission (SRTM) data were used for elevation modeling. Seven radiometric images were produced. The U, Th and K images were selected because showed better visual correlation with geological map than Total Count, Th/K, U/K and U/Th images. The cluster analysis using four clusters and four variables was performed with U, Th, K and topographic data. The cluster map is the visual representation of a statistical procedure which combined geophysical and topographic data from study area. The most important characteristic of cluster map is the presence of two distinctive groups that can be related with radiometric aspects from local rocks. This product showed that higher terrains present high Th and low U. In these areas sedimentary rocks are founded. Lower terrains, with gneissic rocks present low Th and high U.Pages: 3557-356