Concentrações de hematita e goetita em diferentes cenários de mudanças climáticas
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Data
2019-07-31
Autores
Santos, Aline Moreno Ferreira dos
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Universidade Estadual Paulista (Unesp)
Resumo
Nos solos a goetita e hematita são os principais representantes dos óxidos de ferro, estes minerais necessitam de condições distintas para sua formação, e apresentam influências positivas nas propriedades físicas e químicas do solo. Embora os óxidos de ferro sejam considerados estáveis por longo tempo, estes tem apresentado diferenças no teor em intervalo de tempo menor. Existindo ainda os minerais pedogênicos e litogênicos e sendo a disponibilidade destes minerais fortemente relacionados às condições climáticas. O objetivo deste estudo foi relacionar as concentrações de hematita e goetita com as condições climáticas de 30 anos e gerar concentrações desses óxidos em cenário otimista (RCP 2.6) e pessimista (RCP 8.5) de mudanças climática, preconizados Painel Intergovernamental sobre Mudanças Climáticas (IPCC). O cenário otimista indica aumento médio da Temperatura em 1°C e redução da precipitação média em 7,5 mm no planeta. O cenário pessimista indica aumento da temperatura em 2°C e aumento da precipitação em 37,8 mm. Foi realizada uma metanálise para prospecção dos teores de hematita e goetita em solos de diferentes regiões do mundo e informações climáticas foram coletados na plataforma NASA-POWER. Os dados dos teores dos óxidos de ferro e climáticos foram relacionados de diversas formas. O modelo de aprendizagem de maquina, Random florest regressor (RF) foi usado para estimar as concentrações de Hm e Gt para o mundo, mapas de distribuição desses minerais foram criados considerando cenário otimista e pessimista de mudanças climáticas. Os resultados mostram que altas precipitações e baixas temperaturas favorecem a formação de Gt, tornado o ambiente mais redutor e que, altas temperaturas e baixas precipitações ocorre uma maior formação de Hm, pois a desidratação da ferrydrita é acelerada. O cenário otimista de mudanças climáticas indica que irá ocorrer aumento médio de goetita principalmente nos países de clima tropical e subtropical. Enquanto a hematita poderá ocorrer uma redução.
In soils, goetite and hematite are the main representatives of iron oxides. These minerals require distinct conditions for their formation, and have positive influences on the physical and chemical properties of the soil. Although iron oxides are considered stable for a long time, they have presented differences in the content in smaller time interval. There are also the pedogenic and lithogenic minerals and the availability of these minerals is strongly related to the climatic conditions. The objective of this study was to correlate hematite and goethite concentrations with the climatic conditions of 30 years and to generate concentrations of these oxides in an optimistic scenario (RCP 2.6) and pessimistic (RCP 8.5) of climatic changes recommended by the Intergovernmental Panel on Climate Change (IPCC). The optimistic scenario indicates an average increase of the temperature by 1 ° C and a reduction of the average precipitation by 7.5 mm on the planet. The pessimistic scenario indicates an increase in temperature by 2 ° C and an increase in precipitation by 37.8 mm. A meta-analysis was carried out to prospect the hematite and goethite contents in soils from different regions of the world and climatic information was collected on the NASA-POWER platform. The data of the iron and climatic oxides contents were related in several ways. The machine learning model, Random Forest Regressor (RF) was used to estimate the concentrations of Hm and Gt to the world, distribution maps of these minerals were created considering an optimistic and pessimistic climate change scenario. The results show that high precipitations and low temperatures favor the formation of Gt, making the environment more reductive and that, high temperatures and low precipitations, a higher formation of Hm occurs, since the dehydration of the ferrydrite is accelerated. The optimistic climate change scenario indicates that average goethite growth will occur, especially in tropical and subtropical countries. While the hematite may occur a reduction.
In soils, goetite and hematite are the main representatives of iron oxides. These minerals require distinct conditions for their formation, and have positive influences on the physical and chemical properties of the soil. Although iron oxides are considered stable for a long time, they have presented differences in the content in smaller time interval. There are also the pedogenic and lithogenic minerals and the availability of these minerals is strongly related to the climatic conditions. The objective of this study was to correlate hematite and goethite concentrations with the climatic conditions of 30 years and to generate concentrations of these oxides in an optimistic scenario (RCP 2.6) and pessimistic (RCP 8.5) of climatic changes recommended by the Intergovernmental Panel on Climate Change (IPCC). The optimistic scenario indicates an average increase of the temperature by 1 ° C and a reduction of the average precipitation by 7.5 mm on the planet. The pessimistic scenario indicates an increase in temperature by 2 ° C and an increase in precipitation by 37.8 mm. A meta-analysis was carried out to prospect the hematite and goethite contents in soils from different regions of the world and climatic information was collected on the NASA-POWER platform. The data of the iron and climatic oxides contents were related in several ways. The machine learning model, Random Forest Regressor (RF) was used to estimate the concentrations of Hm and Gt to the world, distribution maps of these minerals were created considering an optimistic and pessimistic climate change scenario. The results show that high precipitations and low temperatures favor the formation of Gt, making the environment more reductive and that, high temperatures and low precipitations, a higher formation of Hm occurs, since the dehydration of the ferrydrite is accelerated. The optimistic climate change scenario indicates that average goethite growth will occur, especially in tropical and subtropical countries. While the hematite may occur a reduction.
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Estimativa, Mineralogia, Modelagem, Variáveis ambientais, Estimation, Mineralogy, Modeling, Environmental variables