Downwelling solar irradiance in the biomass burning region of the southern Amazon: Dependence on aerosol intensive optical properties and role of water vapor

The sensitivity of solar irradiance at the surface to the variability of aerosol intensive optical properties is investigated for a site (Alta Floresta) in the southern portion of the Amazon basin using detailed comparisons between measured and modeled irradiances. Apart from aerosol intensive optical properties, specifically single scattering albedo (omega(o lambda)) and asymmetry parameter (g(lambda)), which were assumed constant, all other relevant input to the model were prescribed based on observation. For clean conditions, the differences between observed and modeled irradiances were consistent with instrumental uncertainty. For polluted conditions, the agreement was significantly worse, with a root mean square difference three times larger (23.5 Wm(-2)). Analysis revealed a noteworthy correlation between the irradiance differences (observed minus modeled) and the column water vapor (CWV) for polluted conditions. Positive differences occurred mostly in wet conditions, while the differences became more negative as the atmosphere dried. To explore the hypothesis that the irradiance differences might be linked to the modulation of omega(o lambda) and g(lambda) by humidity, AERONET retrievals of aerosol properties and CWV over the same site were analyzed. The results highlight the potential role of humidity in modifying omega(o lambda) and g(lambda) and suggest that to explain the relationship seen between irradiances differences via aerosols properties the focus has to be on humidity-dependent processes that affect particles chemical composition. Undoubtedly, there is a need to better understand the role of humidity in modifying the properties of smoke aerosols in the southern portion of the Amazon basin.

Mercury emissions from forest burning in southern Amazon

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A NEW SPECIES of AFRICANA (NEMATODA: HETERAKIDAE) FROM LIZARDS of SOUTHERN AMAZON, BRAZIL

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Helminths of lizards from the municipality of Aripuanã in the southern Amazon region of Brazil

Ninety-five specimens from 13 species of lizard collected during a herpetofaunal monitoring programme of the Faxinal II power plant, municipality of Aripuanã, state of Mato Grosso, Brazil (southern Amazon region) were examined for helminths. A total of 21 helminth species (16 Nematoda, 1 Cestoda and 4 Trematoda) were recovered, with an overall prevalence of 67.37%. Seventeen new host records and seven new locality records are reported. A low number of specialists and core helminth species were found. Lizard body size was positively correlated with both the total number of helminth species and individuals. Active foragers exhibited higher helminth diversity. However, sit-and-wait foragers, especially Plica plica, had similar diversity values as active foragers and harboured more helminth species. The degree of similarity in helminth fauna was higher among closely related host species. Copyright © 2011 Cambridge University Press.

Differences in throughfall and net precipitation between soybean and transitional tropical forest in the southern Amazon, Brazil

The expansion of soybean cultivation into the Amazon in Brazil has potential hydrological effects at local to regional scales. To determine the impacts of soybean agriculture on hydrology, a comparison of net precipitation (throughfall, stemflow) in undisturbed tropical forest and soybean fields on the southern edge of the Amazon Basin in the state of Mato Grosso is needed. This study measured throughfall with troughs and stemflow with collar collectors during two rainy seasons. The results showed that in forest 91.6% of rainfall was collected as throughfall and 0.3% as stemflow, while in soybean fields with two-month old plants, 46.2% of rainfall was collected as throughfall and 9.0% as stemflow. Hence, interception of precipitation in soybean fields was far greater than in intact forests. Differences in throughfall, stemflow and net precipitation were found to be mainly associated with differences in plant structure and stem density in transitional forest and soybean cropland. Because rainfall interception in soybean fields is higher than previously believed and because both the area of cropland and the frequency of crop cycles (double cropping) are increasing rapidly, interception needs to be reconsidered in regional water balance models when consequences of land cover changes are analyzed in the Amazon soybean frontier region. Based on the continued expansion of soybean fields across the landscape and the finding that net precipitation is lower in soy agriculture, a reduction in water availability in the long term can be assumed. (C) 2012 Elsevier B.V. All rights reserved.

Forest natural regeneration and biomass production after slash and burn in a seasonally dry forest in the Southern Brazilian Amazon

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mercury in soils and sediments from gold mining liabilities in Southern Amazonia

The 1980-1990 Amazonian gold rush left an enormous liability that increasingly has been substituted by developing fish aquaculture. This work aimed at the identification of the mercury levels in the environment, associated with fish farms located in the North of Mato Grosso State, Southern Amazon. Sediment and soil samples were analyzed for total organic carbon and total mercury. Results indicate that the chemical characteristics of the sediment largely depend on the management procedures of the fish pond (liming, fish food used and fish population). The soils presented relatively low concentrations when compared with other data from the literature.

Endoparasites infecting the semiaquatic coral snake Micrurus surinamensis (Squamata: Elapidae) in the southern amazonian region, Mato Grosso state, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new snake of the genus Helicops Wagler, 1830 (Dipsadidae, Xenodontinae) from Brazil

We describe a new species of Helicops from the southern Amazon Basin in the state of Mato Grosso, Brazil. It differs from all congeners by having dorsal scales in 21/21/19 rows in males and 23/21/19 rows in females, subcaudal keels, a banded dorsal color pattern, and 14-19 ventral blotches. Besides presenting information on the lepidosis and morphometric variation, we also describe the hemipenis and discuss the known distribution of the new species. © 2013 by The Herpetologists' League, Inc.

Caracterização de terras pretas arqueológicas no sul do Estado do Amazonas

The Archaeological Dark Earth (ADE) soils are characterized by its high fertility, dark color, and presence of pottery fragments. Regarding the formation of ADE, the most widely accepted hypothesis is that anthropogenic processes involving pre-Columbian populations made them. The purpose of this study is to characterize ADE units located in the Southern Amazon Region, in the cities of Apuí and Manicoré. Seven ADE sites were selected, trenches opened and the soil profiles characterized morphologically. Then, samples of each horizon were collected for analyses of the following physical and chemical properties: particle size, water-dispersible clay, flocculation, soil bulk density, particle density, total porosity, pH in water and KCl solutions, Ca2+, Mg2+, K+, Al3+, available P, H+Al, and organic C. Also, total oxides, free oxides and amorphous forms were analyzed. The texture of the anthropic A horizon ranged from sandy loam to clay loam. The pottery fragments and lithic material were found in similar quantities and at similar depths in the A horizons of the studied soil profiles, suggesting some similarity between the anthropogenic factors of formation. The anthropic horizons of profiles P3, P4, and P7 had a eutrophic character and high to very high levels of available phosphorus, compared to P1, P2, P5, and P6, indicating the heterogeneity of the ADEs.

Variabilidade espacial de atributos físicos em um cambissolo háplico, sob diferentes usos na região sul do Amazonas

Considering the importance of knowledge of the spatial distribution of soil properties, the purpose of this study was to evaluate the spatial variability of physical properties in a Cambisolunder different land uses in the southern Amazon region. The study was conducted on three farms with cassava, sugarcane, and agroforestry, in the region of Humaitá, in the south of the State of Amazonas. In these areas, 70 x 70 m grids were established, with a regular spacing of 10 x 10 m and a total of 64 points, where soils were sampled at 0.0-0.10 m depth. Texture (sand, silt, and clay), macroporosity, microporosity, total porosity, bulk density, and aggregate stabilitywere determined. The data were analyzed using descriptive statistics and geostatistics. It was found that the propertiesvaried spatially and that the range of these variations between land uses was different, with the highest variability for the sugarcane management.

Variação geográfica, zonas de intergradação e especiação no complexo Icterus Cayanensis-Chrysocephalus (Aves : Icteridae)

O complexo Icterus cayanensis-chtysocephalus apresenta um intrincado padrão de variação em plumagem e tamanho corpóreo. São reconhecidos, tradicionalmente, para o grupo seis táxons: Icterus chtysocephalus, I. cayanensis cayanensís. I. cayanensis tibialis, I. cayanensis tibialis, I. cayanensis valenciobuenoi, I. cayanensis periporphyrus e I. cayanensis pyrrhopterus, que se substituem geograficamente ao longo de grande parte da América do Sul. Neste estudo foi feita a descrição dos padrões de variação geográfica. Foram diagnosticadas quatro espécies, à luz do conceito filogenético de espécie: Icterus cayanensis (Amazônia Meridional), Icterus chrysocephalus (Amazônia Setentrional), Icterus tibialis (Caatinga) e Icterus pyrrhopterus (Chaco); os táxons I. cayanensis valenciobuenoi e I. cayanensis periporphyrus foram sinonimizados. Entre as formas amazonicas (chrysocephalus e cayanensis) foi detectada a presença de uma zona híbrida mais extensa do que aquela reportada na literatura. No Brasil Central foi diagnosticada a maior zona de intergradação conhecida para aves, com aproximadamente 2.300 km de extensão, produto do intercruzamento entre Icterus tibialis e Icterus pyrrhopterus, formas distribuídas pela Caatinga e Chaco, respectivamente. Postula-se que as zonas de intergradação diagnosticadas neste estudo são produto do intercruzamento de populações previamente diferenciadas em isolamento geográfico.

A capa carbonática do sudoeste do cráton amazônico, estado de Rondônia: nova ocorrência e extensão dos eventos pós-glaciação marinoana (635 Ma)

Na porção oeste da Bacia dos Parecis, Estado de Rondônia, inserida no sudoeste do Cráton Amazônico, rochas carbonáticas expostas nas bordas dos grábens Pimenta Bueno e Colorado têm sido consideradas como parte do preenchimento eopaleozoico da bacia. A avaliação das fácies/microfácies e quimioestratigrafia dessas rochas nas regiões de Chupinguaia e Pimenta Bueno, confirmou a ocorrência de dolomitos rosados que sobrepõem, em contato direto, diamictitos glaciais previamente interpretados como depósitos de leques aluviais. Trabalhos prévios reportaram excursão negativa de δ¹³C, também confirmados neste trabalho, com variações entre -4.6 e -3,8‰VPDB em Chupinguaia e média de - 3,15‰VPDB em Pimenta Bueno. Esse padrão, de sedimentação e quimioestratigráfico, ausente nas rochas paleozoicas, é comumente encontrado nos depósitos carbonáticos anômalos do Neoproterozoico. No sul do Cráton Amazônico, Estado do Mato Grosso, rochas com essas mesmas características são descritas como capas carbonáticas relacionadas à glaciação marinoana (635 Ma). Neste trabalho, consideramos que os dolomitos rosados sobre diamictitos, em Rondônia, fazem parte do mesmo contexto das capas carbonáticas encontradas no Mato Grosso. Adicionalmente, destaca-se o contato brusco e deformado do dolomito sobre o diamictito, presente em ambas as ocorrências, configurando-se uma das feições típicas das capas carbonáticas do Cráton Amazônico. Essa relação paradoxal, entre diamictito e dolomito, tem sido interpretada como produto da mudança rápida das condições atmosféricas de icehouse para greenhouse, e a deformação da base foi gerada pelo rebound isostático. A capa carbonática de Rondônia compreende duas associações de fácies (AF2 e AF3) que recobrem depósitos glacio-marinhos compostos por paraconglomerados polimíticos (Pp), e arenito seixoso laminado (Asl), da AF1. A AF2 consiste em dolomudstone/dolopackstone peloidal com laminação plana a quasi-planar e com truncamentos de baixo-ângulo (fácies Dp), megamarcas onduladas (fácies Dm) e laminações truncadas por ondas (fácies Dt), interpretada como depósitos de plataforma rasa influenciada por ondas. Esta sucessão costeira é sucedida pela AF3, que compreende as fácies: dolomudstone/dolopackstone e dolomudstone/dolograinstone com partição de folhelho (Df) e siltito laminado (Sl). A fácies Df compreende um pacote de 6 metros de dolomito com partição de folhelho, apresentando lâminas de calcita fibrosa (pseudomorfos de evaporito) e dolomitos com laminações onduladas de corrente. Sobrejacente à fácies Df, ocorre a fácies Sl, apresentando 5 metros de siltito argiloso com laminação plana. Esta associação é interpretada como depósitos de plataforma rasa influenciada por maré, sendo sobreposta discordantemente, em contato angular, por depósitos glaciais do Eopaleozoico. Os valores isotópicos de C e O são negativos e refletem o sinal primário do C. No entanto, pode-se considerar uma leve influência da diagênese meteórica no sinal. As principais quebras nos sinais negativos podem estar associadas à influência meteórica, expressa pela substituição e preenchimento de poros por calcita e pela proximidade de superfícies estratigráficas, os quais refletem alguns padrões de alteração diagenética, representados nos sinais mais negativos. Diferentemente da capa carbonática do Mato Grosso, a capa de Rondônia possui níveis de pseudomorfos de evaporito e dolomitos com partição de folhelho (ritmito), em sucessão de fácies marinha rasa, onde os dolomitos de plataforma rasa influenciada por ondas passam para ritmitos e siltitos de plataforma rasa influenciada por maré (zona de inframaré), configurando uma sucessão retrogradante. Esta nova ocorrência de capa carbonática modifica a estratigrafia da base da Bacia dos Parecis, ao passo que exclui essas rochas carbonáticas da sequência eopaleozoica. Além disso, fornece informações que permitem reconstruir melhor a paleogeografia costeira da bacia neoproterozoica que acumulou os depósitos da plataforma carbonática do Grupo Araras, bem como estende os eventos pós-marinoanos ligados à hipótese do Snowball/Slushball Earth para o sudoeste do Cráton Amazônico, exposto no Estado de Rondônia.

Depósitos carbonáticos de Tangará da Serra (MT): uma nova ocorrência de capa carbonática neoproterozóica no sul do Cráton Amazônico

Capas carbonáticas se traduzem num dos mais importantes depósitos relacionados ao final das glaciações globais neoproterozóicas. Na região de Tangará da Serra, margem sul do Cráton Amazônico, foi descrita uma sucessão carbonática neoproterozóica de aproximadamente 20 m de espessura que inclui o topo da Formação Mirassol d'Oeste e a base da Formação Guia, respectivamente as capas dolomítica e calcária da base do Grupo Araras. A capa dolomítica é composta por dolograisntones peloidais rosados com laminação plano paralela e truncamentos de baixo ângulo, interpretados como registros de uma plataforma rasa a moderadamente profunda. A capa calcária consiste em siltitos maciços e laminados e calcários finos cristalinos com acamamento de megamarcas onduladas, interpretados como depósitos de plataforma mista moderadamente profunda dominada por ondas. Calcários finos cristalinos com laminação ondulada/marcas onduladas e leques de cristais (pseudomorfos de aragonita) intercalados com folhelhos foram interpretados como depósitos de plataforma profunda e supersaturada em CaCO₃. Calcários com estruturas de escorregamento (slump), laminações convolutas e falhas sin-sedimentares caracterizam depósitos de talude e diques neptunianos, preenchidos por brechas calcárias, e camadas deformadas isoladas sugerem atividade sísmica durante a sedimentação. A sucessão carbonática de Tangará da Serra estende a ocorrência de capas carbonáticas no sul do Cráton Amazônico e corrobora com a presença de uma extensa plataforma carbonática formada durante a transgressão após a glaciação Puga correlata ao evento Marinoano.

Geoestatística na avaliação dos atributos físicos em latossolo sob floresta nativa e pastagem na Região de Manicoré, Amazonas

The use of geostatistical techniques allows detection of the existence of dependence and the spatial distribution of soil properties, thus constituting an important tool in the analysis and detailed description of the behavior of soil physical properties. The aim of the present study was to use geostatistics in assessment of physical properties in a Latossolo (Oxisol) dystrophic under native forest and pasture in the Amazon region of Manicore. Grids with of 70 x 70 m were established in native forest and pasture, and points were marked in these grids spaced at every 10 m, for a total of 64 points. These points were then georeferenced and in each one, soil samples (128) were collected at the depths of 0.00-0.20 and 0.40-0.60 m for a survey of their physical properties. These grids are parallel at a distance of 100 m from one another. The following determinations were made: texture, bulk density and particle density, macroporosity, microporosity, total porosity and aggregate stability in water. After tabulating the data, descriptive statistical analysis and geostatistical analysis were performed. The pasture had a slight variation in its physical properties in relation to native forest, with a high coefficient of variation and weak spatial dependence. The scaled semivariograms were able to satisfactorily reproduce the spatial behavior of the properties in the same pattern as the individual semivariograms, and the use of the parameter range of the semivariogram was efficient for determining the optimal sampling density for the environments under study. The geostatistical results indicate that the removal of native forest for establishing pasture altered the natural variability of the physical properties.