RESUMO

Brazil's Midwest is composed of four biomes: the Cerrado, predominant in the region; the Pantanal, the largest wetland in the world; the Amazon, which occupies part of Mato Grosso; and the Atlantic Forest. The objective of this study was to identify the evolution of occupation and use of land in the rural settlements of the Brazilian Midwest depending on the biome of location. A total of 54 settlements distributed in the four biomes of the region were analyzed using direct observation and Landsat images from the years 2004 and 2014. Using the software QGIS 2.8 Wien, the vegetation indices NDVI and NDWI were used to classify agricultural, pasture and forest areas by biome. Native vegetation is declining in most of the analyzed settlements and pastures, for milk production, occupied the largest area. Between 2004 and 2014, pasture areas expanded to the detriment of forests. Although they have the highest percentage of environmental preservation areas, the settlements we analyzed in the Amazon biome do not comply with legislation. Part of the forest in these settlements was transformed into areas of bushy cerrado. However, there was an increase in forests in the settlements of the Atlantic Forest biome.

Assuntos

RESUMO

Brazil's Midwest is composed of four biomes, the Cerrado (Brazilian savannah), predominant in the region; the Pantanal, the largest irrigated plain on the planet; the Amazon biome; and the Atlantic Forest. The Midwest is the largest producer of grains and livestock in Brazil, activities that have a negative impact on environmental preservation. Agrarian reform redistributes land and reinforces small family farming, which many authors consider as favorable to environmental protection. The objective of this study is to characterize the impact of agrarian reform on environmental preservation and agriculture on each biome of the Brazilian Midwest. Fifty-four settlements were surveyed using direct observation and Landsat images available for the year 2014. QGIS software 2.8 Wien was applied to calculate NDVI and NDWI vegetation indices to classify areas of agriculture, pasture, and environmental preservation. Pasture and savannah land occupy the largest areas in all biomes, with the main human activity based on livestock. Most settlements in the Midwest lead to small-scale activities such as dairy farming and polyculture, practices that differ from large-scale farming based on monoculture, and are more favorable to environmental protection.

Assuntos

RESUMO

The Midwest region of Brazil has a high concentration of land and is the primary producer of grains and livestock in the country, activities with a negative impact on environment. Agrarian reform allows redistribution of land and reinforces family agriculture, which is considered to be favorable to environmental protection. The aim of this study was to use field and remote observations to verify the evolution of environmental preservation and land use in rural settlements in the Midwest region of Brazil. 54 settlements distributed in the region were analyzed. We used images from Landsat 5 satellite obtained by the Thematic Mapper sensor in 2004 and images from Landsat 8 satellite from 2014. The NDVI and NDWI vegetation indexes were used to classify urban, agricultural, pasture, savannah and forest areas. Forests declined in all states, however Mato Grosso, the only one with Amazonian forest, where settlements presented lowest compliance with environmental legislation. The evolution indicates the transformation of forest areas into savannah. Settlers predominantly engage in dairy farming, which requires large areas of land and thus exerts significant pressure on the environment. Productive areas are poorly exploited, and better technical assistance could have a significant impact on environmental protection.

Assuntos

RESUMO

Pantanal da Nhecolândia is one of the most well-preserved areas in the State of Mato Grosso do Sul. Located in the southern part of the Taquari River megafan, it is in tectonic contact with the fault escarpments of the Maracaju-Campo Grande plateaus to the east and with the fault escarpments of the Bodoquena plateau to the west, which continue to north. To the south and to the north, the limits are marked respectively by the lineaments of the Negro and Taquari Rivers. Nhecolândia is characterized by the existence of at least 17,631 lagoons, 17,050 (96.70 %) of which are of fresh water (baías) and 577 (3.3 %) of salty water (salinas). Studies based on (Landsat) satellite images and use of free software (QGIS, version 2.8.3) and GIS (Geographic Information Systems) revealed that the major axes of the lagoons are aligned along two directions, NE (62.49 %) and NW (37.51 %), with modes concentrated between N30-40E and N30-40W, suggesting in both cases the role played by tectonic control (neotectonics) in their formation. Evidences of fluvial origin are presented for these groups of lagoons, as well as for their tectonic alignment.

RESUMO

This paper presents a study of the structural lineaments of the Pantanal extracted visually from satellite images (CBERS-2B satellite, Wide Field Imager sensor, a free image available in INTERNET) and a comparison with the structural lineaments of Precambrian and Paleozoic rocks surrounding the Cenozoic Pantanal Basin. Using a free software for satellite image analysis, the photointerpretation showed that the NS, NE and NW directions observed on the Pantanal satellite images are the same recorded in the older rocks surrounding the basin, suggesting reactivation of these basement structural directions during the Quaternary. So the Pantanal Basin has an active tectonics and its evolution seems to be linked to changes that occurred during the Andean subduction.

Assuntos

RESUMO

The Pantanal of Nhecolândia, the world's largest and most diversified field of tropical lakes, comprises approximately 10,000 lakes, which cover an area of 24,000 km(2) and vary greatly in salinity, pH, alkalinity, colour, physiography and biological activity. The hyposaline lakes have variable pHs, low alkalinity, macrophytes and low phytoplankton densities. The saline lakes have pHs above 9 or 10, high alkalinity, a high density of phytoplankton and sand beaches. The cause of the diversity of these lakes has been an open question, which we have addressed in our research. Here we propose a hybrid process, both geochemical and biological, as the main cause, including (1) a climate with an important water deficit and poverty in Ca(2+) in both superficial and phreatic waters; and (2) an elevation of pH during cyanobacteria blooms. These two aspects destabilise the general tendency of Earth's surface waters towards a neutral pH. This imbalance results in an increase in the pH and dissolution of previously precipitated amorphous silica and quartzose sand. During extreme droughts, amorphous silica precipitates in the inter-granular spaces of the lake bottom sediment, increasing the isolation of the lake from the phreatic level. This paper discusses this biogeochemical problem in the light of physicochemical, chemical, altimetric and phytoplankton data.

Assuntos

RESUMO

The Pantanal of Nhecolândia, the world's largest and most diversified field of tropical lakes, comprises approximately 10,000 lakes, which cover an area of 24,000 km² and vary greatly in salinity, pH, alkalinity, colour, physiography and biological activity. The hyposaline lakes have variable pHs, low alkalinity, macrophytes and low phytoplankton densities. The saline lakes have pHs above 9 or 10, high alkalinity, a high density of phytoplankton and sand beaches. The cause of the diversity of these lakes has been an open question, which we have addressed in our research. Here we propose a hybrid process, both geochemical and biological, as the main cause, including (1) a climate with an important water deficit and poverty in Ca2+ in both superficial and phreatic waters; and (2) an elevation of pH during cyanobacteria blooms. These two aspects destabilise the general tendency of Earth's surface waters towards a neutral pH. This imbalance results in an increase in the pH and dissolution of previously precipitated amorphous silica and quartzose sand. During extreme droughts, amorphous silica precipitates in the inter-granular spaces of the lake bottom sediment, increasing the isolation of the lake from the phreatic level. This paper discusses this biogeochemical problem in the light of physicochemical, chemical, altimetric and phytoplankton data.

O Pantanal da Nhecolândia é o maior e mais diversificado campo de lagos da região tropical do planeta, com cerca de 10.000 lagos de variadas salinidade, pH, alcalinidade, cor, fisiografia e atividade biológica dispostos em uma área de 24.000 km². Os lagos hipossalinos têm pH variável, baixa alcalinidade, macrófitas e baixa densidade de fitoplâncton. Os lagos salinos tem pH acima de 9 ou 10, elevada alcalinidade, alta densidade de fitoplâncton e praias de areia. A causa da diversidade desses lagos é uma questão ainda em aberto que é abordada nesta pesquisa. Propõe-se como principal causa um processo híbrido, geoquímico e biológico, baseado em (1) clima com um déficit hídrico importante e pobreza em Ca2+na água superficial e do freático e (2) na elevação do pH durante florações de cianobactérias. Estes dois aspectos desestabilizam a tendência geral de pH neutro para as águas superficiais da Terra. Este desequilíbrio resulta em aumento do pH e dissolução da areia quartzosa do fundo dos lagos salino-alcalinos. Durante secas extremas há precipitação de sílica amorfa nos espaços inter-granulares dos sedimentos de fundo destes lagos, aumentando seu isolamento do freático. O artigo discute este processo biogeoquímico, à luz de dados físico-químicos, químicos, fitoplânctonicos e de altimetria de precisão.

Assuntos