De Caldas Plateau Research Articles

Odonata (Insecta) en campos de gran altitud y ecosistemas asociados en la meseta de Poços de Caldas, Brasil

The High Altitude Fields (HAF) are unique phytosociological features that occur only in certain regions of the Atlantic Forest. It is composed of herbaceous and shrubby vegetation and shallow soils that promote local water infiltration and recharge. Occurring on top of hills, the HAF are isolated units in the landscape, connecting with the matrix through associated ecosystems (springs with riparian forests and “capões de mata”, which are natural islands of arboreal vegetation, commonly associated with rural vegetation, such as high-altitude fields, located above 1,200 m in phytogeographic domains of the Atlantic Forest, Cerrado or Caatinga). These areas have great species endemism, and studies concerning the order Odonata are still scarce. Thus, we aimed to evaluate the ecological responses (richness, diversity, specificity) of adult odonates in these ecosystems. The study was conducted from November 2020 to March 2021 in three areas in the Poços de Caldas Plateau, Minas Gerais state, Brazil. A total of 45 species (247 specimens) were collected, with the highest total richness being recorded for Anisoptera. Among the sampled areas, there was no difference in Anisoptera communities, but there was a difference in Zygoptera species composition. In general, the most preserved remnant of HAF, the greater it presents greater richness of Odonata and harbors a regional pool of species.

Avispas sociales (Hymenoptera: Vespidae) asociadas a plantaciones de Eucalyptus sp. en un Campo de Altitud situado en el sur del Estado de Minas Gerais, Brasil

In Brazil, there is little information about social wasp communities in Altitude Fields (Campos de Altitude), a phytophysiognomy of the Atlantic Forest with a high rate of endemism, which is being altered and reduced in area by human activities, such as the cultivation of Eucalyptus spp. Therefore, the present study aimed to inventory the species of Polistinae (Vespidae) presente in an Altitude Field associated with Eucalyptus sp. plantations in the municipality of Poços de Caldas, Southern Minas Gerais, Brazil. The study was conducted in Morro do Ferro, central region of the Poços de Caldas Plateau, from 2020 to 2021, using active search and Malaise traps. Thirteen species of social wasps were recorded, which have a wide geographic distribution, and explore anthropic environments, such as agricultural areas, pasture and Eucalyptus sp. plantations. Many of them behave as synanthropic, suggesting this altitude field to be a degraded area in Poços Caldas, MG. However, further studies must be carried out in the region, in order to know and preserve these remaining ecosystems.

Naturally-Occurring Radioactive Materials at water treatment plant on the Poços de Caldas Plateau Region, Brazil

ABSTRACT Oil and gas, mining, among others, are examples of facilities where naturally occurring radioactive materials can be found. This study aims to evaluate the presence of natural radioactive series, especially those of 238U and 232Th, in the water treatment plants of Poços de Caldas City, Minas Gerais. The presence of these series was investigated in samples of raw water, treated water, sludge from decanters, and scale from Parshall gutters. The sludge, input, and scale samples were submitted to the gamma spectrometry technique to determine the 226Ra, 228Ra, and 210Pb radionuclides. For U and Th, ultraviolet visible spectrophotometry was performed, and for the alpha and beta total values, radiochemical separation and subsequent alpha and beta total counts were performed. The results indicate that water samples are within the Ministry of Health Ordinance n° 5 (2017). Due to the different concentrations of radionuclide activity in the sludge, it was not possible to affirm the same order of magnitude with the sediment from the catchments. However, the values are in accordance with those established by the European Union Council for Naturally-Occurring Radioactive Materials. In the scale, the contents of 1192, 1704, and 301 Bq kg−1 were identified for 226Ra, 228Ra, and 210Pb, respectively. In the inputs of aluminum sulfate and calcium hydroxide, no relevant activities were identified. The results obtained in the study can serve as an indicative regarding the need for a more detailed evaluation of the radiological issue in question concerning public water supplies.

Checklist of polypores (Agaricomycetes, Basidiomycota) reveals seventeen new records in Brazilian Atlantic Forest fragments at the Poços de Caldas Plateau, Minas Gerais

Abstract This is the first survey of macrofungi carried out at the Poços de Caldas Plateau, Minas Gerais, Brazil, an area of high biological importance according to the Ministry of Environment. The survey of polypores was performed monthly, from June/2018 to May/2019 in ten transects (200 m² each) distributed in fragments of the Brazilian Atlantic Forest, a montane seasonal semideciduous forest. Two orders, 8 families, 21 genera, and 23 species were identified, of which one is a new record for Brazil, Tropicoporus drechsleri, and 16 are new records for the state of Minas Gerais. A list of species is included in this study, as well as illustrations for the new records, a key for taxonomic identification, and remarks on the distribution of the recorded species. The study also includes annotations about substrate, taxonomy discussion, and a full description of the new record for the country.

A Comparative Study of Methods for Determining the Concentration of Radon-222 in Spring Waters in Poços de Caldas Plateau, Brazil

Este estudo é uma comparação de métodos para determinar a concentração de radônio (222Rn), que foi realizado em fontes de água natural utilizadas pela população das cidades de Poços de Caldas e Águas da Prata no Planalto de Poços de Caldas, no sudeste do Brasil. O planalto está localizado em área afetada pela reativação de processos vulcânicos que ocorreram durante sua formação. Este é o maior complexo alcalino no Brasil e caracterizado por uma caldeira vulcânica de cerca de 30km de diâmetro, constituída por rochas ígneas plutônicas, onde são encontradas anomalias de urânio e tório. As amostragens foram realizadas em fontes naturais de água distribuídas pelas cidades e a concentração de 222Rn nas águas foi determinada em Becquerel por litro. Os níveis de radiação encontrados nas fontes naturais foram comparados com os limites das doses totais absorvidas por um indivíduo e os padrões de proteção radiológica estabelecidos pela Organização Mundial de Saúde (OMS). A determinação da concentração de atividade de 222Rn encontrada nas águas foi possível através da captura de partículas alfa emitidas pelo decaimento do elemento, realizadas com o equipamento profissional de monitoramento de radônio (AlphaGUARD) e também pelo do método de contagem de cintilação líquida, utilizando equipamento da marca Camberra PACKARD. Os maiores valores aferidos foram de 657,2 Bq.L-1, medido pelo AlphaGUARD e, 513,2 Bq.L-1, obtido através do método de cintilação líquida.

Combined hydrochemical, isotopic, and multivariate statistics techniques to assess the effects of discharges from a uranium mine on water quality in neighboring streams

The Caldas Uranium Mine (CUM), located on the Pocos de Caldas Plateau in the southeastern region of Brazil, is presently undergoing a decommissioning process. The aim of the present investigation is to identify and characterize the effects of acid mine drainage (AMD) originating from the CUM on surface water quality. To achieve these aims, sampling stations were located at two AMD sources: the retention pond at the foot of waste rock pile#4 (WRP#4) and the settling pond that receives effluents from the tailings dam (TD). Ten additional sampling stations were located along watercourses in the vicinity, both downstream and upstream of the mine. Sampling was performed during the rainy and dry seasons in 2010 and 2011. The water analysis detected significant changes in pH, electrical conductivity, F−, Cd, U, Zn, Al, Mn, As, Ca, SO4 2−, Pb, 238U, 226Ra, 210Pb, 232Th, 228Ra, and Mo in waters downstream of both pond discharge sites. It was demonstrated that the disequilibrium between 226Ra and 238U can be used to trace the extent of AMD impacts in nearby streams. Variations in 18O and 2H enabled the flow of mining-impacted water to be traced from the ponds to nearby streams. Multivariate analysis yielded a three-factor model: Factor 1 was interpreted as being associated with AMD (from WRP#4) and Factor 2 with a Ca–Mo relationship associated with the chemical constitution of the ore and with the treatment of tailings wastes in the area (from TD); Factor 3 was interpreted as being associated with the natural influence of geogenic processes on water quality in the area. The results of this study provide a scientific basis for recommending appropriate remedial actions during mine decommissioning.

Riqueza de mudas de espécies florestais nativas potencialmente produzidas na Bacia do Rio Grande, MG

A restauração ecológica do papel fundamental na retomada da integridade dos ecossistemas, a partir do restabelecimento da riqueza das espécies e da estrutura das comunidades vegetais. Assim, caso seja a realização de uma realização de planejamento, uma produção de mudas florestais com alta riqueza específica subsidiado ou sucesso da prática. O objetivo deste estudo foi analisar a riqueza de mudas de espécies florestais nativas potencialmente produzidas em viveiros na Bacia do Rio Grande, sul de Minas Gerais. A análise foi revisada no Catálogo das Árvores Nativas de Minas Gerais, considerando como espécies presentes nos subdomínios fitogeográficos Alto Rio Grande, Mantiqueira Sul, Planalto de Poços de Caldas e Noroeste. Para análise das espécies com potencial de produção nos viveiros da Bacia do Rio Grande, Foram utilizados nos dados do registro nacional de sementes e mudas (RENASEM) de 2013. Foram encontradas 1.251 espécies de ocorrência natural, 102 espécies cadastradas e 49 produtos de consumo, distribuídos em 36 municípios. Apenas cinco séries presentes na lista oficial de espécies ameaçadas de extinção foram cadastradas pelas unidades de produção. A riqueza de espécies florestais cadastradas por produto importado Não RENASEM na região estudada é muito baixa, o que pode comprometer o sucesso dos projetos de restauração ecológica.

Diversity of medium-sized and large mammals from Atlantic Forest remnants in southern Minas Gerais state, Brazil

Studies on mammal diversity provide the essential groundwork for the development of conservation methods and practices. The region of the Poços de Caldas Plateau is lacks such studies, which may be a problem for future conservation actions. Here, we analyze the richness of medium-sized and large mammals from Atlantic Forest remnants on the Poços de Caldas Plateau, Minas Gerais state. Diurnal censuses of direct observations and mammal signs were conducted, and we documented 20 species of mammals belonging to eight orders. Three species of primates, one carnivore, one cingulate, one lagomorpha, three rodents, one artiodactyla, and two marsupials were found. The largest forest remnant that presented the greatest richness is currently a conservation unit. Forest remnants are important for the consolidation of management strategies and have fundamental role for the conservation of mammal diversity in the south of Minas Gerais state.

Hydrochemical assessment of surface water in watersheds near the Uranium Mining and Milling Facilities of Caldas, Brazil

Sited in the Pocos de Caldas Plateau, in south-eastern Brazil, the Uranium Mining and Milling Facilities (UMMF) of Caldas are in the process of decommissioning. The main environmental problem in this site is the generation of acid mine drainage (AMD) in the tailings dam, open pit and waste rock piles. The aim of this work is to evaluate, by hydrochemical studies, the influence of acidic effluents from the Caldas UMMF, on the hydrochemistry of surface water along three watersheds: Consulta Brook, Soberbo Creek and Taquari River. Twelve sampling stations were established to carry out the investigation. Two of them were located at effluent retention ponds. Sampling was performed in the rainy and dry seasons of 2011, and the measured parameters were Eh, pH, EC (electrical conductivity), SO42−, HCO3−, Cl−, Na+, K+, Ca2+, Mg2+ and Fe. The results have shown that iron is not a main constituent of the ionic composition of the local AMD. It could also be observed that acidic effluents were being discharged from retention ponds into the watercourses, causing a pronounced increase of the sulfate and calcium concentrations downstream. To trace the AMD migration the (SO42−/HCO3−)/(Na+ + K+/Ca2+) ratio was used. A detailed investigation of the near-surface groundwater is recommended downstream of the effluent ponds sites to evaluate the need for mitigating actions such as constructing hydraulic barriers. The present article shows that using simple techniques, such as Eh–pH and Piper diagrams, it is possible to depict the AMD fluvial migration pattern, which is an important information both to the authority responsible incumbent upon the remediation of the site, and to the affected interested parties who inhabit the impacted region.

A New Subspecies ofAnthanassa(Nymphalidae: Nymphalinae: Melitaeini) from Southeastern Brazil

ABSTRACT. A new subspecies of Anthanassa drusilla, ssp rioverde, is described from Minas Gerais, Southeastern Brazil. This new subspecies is isolated from all other known subspecies of A. drusilla by at least 2000 km, and its closest taxon based on wing pattern is Anthanassa drusilla higginsi, from Cerro Neblina, Venezuela. To our knowledge, the species is endemic to the region of Pocos de Caldas Plateau (Minas Gerais), a region of high natural radiation and heavily impacted by mining. Since the entire geographic distribution and conservation status of this subspecies is unknown, it is highly recommended that immediate measures are taken to minimize the environmental impact on the area of occurrence of this butterfly.

The Use of the Stream Length-Gradient Index in Morphotectonic Analysis of Drainage Basins in Poços de Caldas Plateau, SE Brazil

The Pocos de Caldas Plateau is formed by the alkaline intrusion of Pocos de Caldas and surrounding metamorphic basement. It is characterized as a remnant of the South American Planation Surface resulted from erosional events from Late Cretaceous-Paleogene transition. Pocos de Caldas Alkaline Massif (PCAM) was formed during alkaline volcanism event from the Late Cretaceous. It is located on the west side of the Mantiqueira Mountain Range, characterized by alkaline rocks and topography reaches over 1700 m high. A major feature of denudation is the development of the “circular drainage”, a particular feature of some caldera and other circular or concentric structural features. Recent tectonic movements may critically affect regional geomorphology by influencing river patterns and orientations. The morphometric analysis shows that some rivers are controlled by reactivated faults, however, in some regions the lithology has major influence in the rivers development.

Soil physical properties of high mountain fields under bauxite mining

Mining contributes to the life quality of contemporary society, but can generate significant impacts, these being mitigated due to environmental controls adopted. This study aimed to characterize soil physical properties in high-altitude areas affected by bauxite mining, and to edaphic factors responses to restoration techniques used to recover mined areas in Poços de Caldas plateau, MG, Brazil. The experiment used 3 randomized block design involving within 2 treatments (before mining intervention and after environmental recovery), and 4 replicates (N=24). In each treatment, soil samples with deformed structures were determined: granulometry, water-dispersible clay content, flocculation index, particle density, stoniness level, water aggregate stability, and organic matter contend. Soil samples with preserved structures were used to determine soil density and the total volume of pores, macropores, and micropores. Homogenization of stoniness between soil layers as a result of soil mobilization was observed after the mined area recovery. Stoniness decreased in 0.10-0.20 m layer after recovery, but was similar in the 0-0.10 m layer in before and after samples. The recovery techniques restored organic matter levels to pre-mining levels. However, changes in soil, including an increase in soil flocculation degree and a decrease in water-dispersible clays, were still apparent post-recovery. Furthermore, mining operations caused structural changes to the superficial layer of soil, as demonstrated by an increase in soil density and a decrease in total porosity and macroporosity. Decreases in the water stability of aggregates were observed after mining operations.

Cost analysis and ecological benefits of environmental recovery methodologies in bauxite mining

This work analyzed and compared three methods of environmental recovery in bauxite mining commonly used in Poços de Caldas Plateau, MG, by means of recovery costs and ecological benefits. Earnings and costs data of environmental recovery activities were obtained for the areas that belonged to the Companhia Geral de Minas - CGM, on properties sited in the city of Poços de Caldas, MG. The amount of costs of these activities was used to compare the recovery methods by updating them monetarily to a reference date, in other words, the present moment. It is concluded that the difference between the present value of costs for simple restoration and rehabilitation activities are less than 1% and that between the complete restoration and rehabilitation is about 15.12%, suggesting that the choice of the methods to be used must be based on the ecological earnings proportional to each of them. The methodology of environmental restoration of the mining areas emphasizes the ecological variables in the process of establishment of the community, to the detriment of complex ecological aspects, which show difficulties in measuring the actual moment of the development of the ecosystem considered.

Characterization of the bauxite mining of the Poços de Caldas alkaline massif and its socio-environmental impacts

The intensive use of mineral resources brings along significant changes to the environment. The mining sector is essential for world economics, as long as it is operated on a basis that is technically coherent, socially fair and environmentally correct. This study aimed to characterize the bauxite mining of the Poços de Caldas plateau, MG, investigating its respective socio-environmental impacts. Through the overview presented, one can conclude that in most situations, the bauxite miningat the Poços de Caldas plateau mitigates its negative social and environmental impacts in a satisfactory manner in addition to generating positive social impacts; and the restoration methods of the mining-disturbed ecosystems have been continually improved and should be replicated by small-and-medium-sized companies.

Spatial analysis techniques applied to mineral prospecting: an evaluation in the Poços de Caldas plateau

Boolean Logic, Weighted Means, Fuzzy/AHP (Analytical Hierarchic Process), Fuzzy Gamma, and Bayesian Weight of Evidence (WofE) spatial analysis techniques were evaluated to address potential areas for radioactive mineral prospecting in the Poços de Caldas Plateau, Brazil. These techniques were applied according to a prospecting model based on diagnostic criteria, such as favorable lithologies, structural features and gamma ray (total count) data. Resulting maps were organized into four classes of potentiality (null, low, middle and high potential), which express different levels of favorability for radioactive mineral occurrences in the study area. To compare the performance of the resulting scenarios, some 48 known radioactive mineral occurrences were used. Cross-tabulation technique was applied to measure the confidence grade (conditional probability) of each potential class. According to the results, the scenarios showed different performances. The Boolean Logic-based scenario proved to be limited, whereas result of the Fuzzy Gamma technique was unsatisfactory. However, very good results were obtained with the scenarios derived from the Bayesian WofE, Fuzzy/AHP, and Weighted Means techniques, indicating that spatial inference techniques can be useful guides in mineral prospecting campaigns.

Spatial analysis techniques applied to mineral prospecting: an evaluation in the Poços de Caldas plateau

Boolean Logic, Weighted Means, Fuzzy/AHP (Analytical Hierarchic Process), Fuzzy Gamma, and Bayesian Weight of Evidence (WofE) spatial analysis techniques were evaluated to address potential areas for radioactive mineral prospecting in the Pocos de Caldas Plateau, Brazil. These techniques were applied according to a prospecting model based on diagnostic criteria, such as favorable lithologies, structural features and gamma ray (total count) data. Resulting maps were organized into four classes of potentiality (null, low, middle and high potential), which express different levels of favorability for radioactive mineral occurrences in the study area. To compare the performance of the resulting scenarios, some 48 known radioactive mineral occurrences were used. Cross-tabulation technique was applied to measure the confidence grade (conditional probability) of each potential class. According to the results, the scenarios showed different performances. The Boolean Logic-based scenario proved to be limited, whereas result of the Fuzzy Gamma technique was unsatisfactory. However, very good results were obtained with the scenarios derived from the Bayesian WofE, Fuzzy/AHP, and Weighted Means techniques, indicating that spatial inference techniques can be useful guides in mineral prospecting campaigns.

Preliminary indoor radon risk assessment at the Poços de Caldas Plateau, MG – Brazil

This paper aims to present an assessment of the environmental radiological exposure at a Brazilian area of high natural radiation and discusses the indoor radon exposure risk. A survey of inhabitant exposures arising from the inhalation of radon progeny and external gamma exposure was conducted in urban and rural areas of the Poços de Caldas Plateau, which is recognized worldwide as a high natural radiation region. The results of this survey indicated that highest radiation exposure was restricted to the rural area of Poços de Caldas. The radiation exposure in urban locations was quite similar to the values observed in normal background areas in some Brazilian counties. By the application of a constant relative risk model, an additional 20% in the lifetime risk of lung cancer mortality due to the exposure to radon progeny was estimated at Poços de Caldas. It was also estimated that 16% of all lung cancer deaths at Poços de Caldas county could be attributable to radon exposure.

Biological Response of Tradescantia Stamen-hairs to High Levels of Natural Radiation in the Poços de Caldas Plateau

The objective of the present study was to apply a highly sensitive botanical test of mutagenicity (the Tradescantia stamen-hair mutation bioassay) to assess in situ the biological responses induced by naturally occurring radiation in the Poços de Caldas Plateau. The mutagenesis was evaluated in environments presenting gamma radiation exposure rates ranging from 1.5 muR.min-1 up to 100.0 muR.min-1. The results consistently showed only borderline increases in mutation frequencies in plants exposed to areas with high radiation background, as compared to non-exposed plants. It was concluded that the levels of natural radiation prevalent in the Poços de Caldas Plateau were not sufficient to induce significant increases in mutation rate, even in the extremely sensitive Tradescantia stamen hair mutation bioassay and mutagenesis evaluation test could be a useful monitoring system for natural radiation exposure.

A method for evaluating 228Ra in environmental matrices and its use at Poços de Caldas plateau, Brazil

This work describes a methodology developed for performing the extraction, detection and quantification of 228Ra in waters, suspended solids and sediments. The technique proved to be useful for analyzing samples from the hydrological environment of Morro do Ferro, Poços de Caldas plateau, Brazil. The 228Ra activity in underground waters of 5 boreholes drilled in the area varied from 0.02 up to 14.5 Bq/l, whereas for the surficial waters the variation was from 0.04 to 0.51 Bq/l; for the suspended solids, the values ranged from 1.5 up to 419 Bq/g, whereas it was possible to find a value of 2.04 Bq/g for the sediments. These results show the applicability of the method for characterizing different matrices of environmental interest.

Determination of alpha-emitting isotopes of uranium and thorium in vegetables and excreta

A radiochemical procedure for the determination of alpha-emitting isotopes of uranium and thorium in vegetables and excreta has been optimized, involving sample dissolution, separation by ionic exchange resin, electrodeposition and alpha-spectroscopy. Uranium and thorium isotopes were determined separately to prevent interference of 228Th from 232U tracer with 228Th from natural series of 232Th. This procedure was applied to faeces from people living in the Pocos de Caldas plateau, a high natural radioactivity region of Brazil, and vegetables from the Laboratory of Environmental Monitoring (EML/DOE). Results show a chemical recovery of 80–95% for uranium and 46–72% for thorium.