Micronutrient reserves and availability and comparison of two extraction methods in agricultural soils from santa fe

Los objetivos del trabajo fueron determinar los contenidos pseudototales, disponibles y ligados a las distintas fracciones químicas de Cu, Zn, Mn y Fe en Argiudoles de la pampa llana santafesina y comparar la concentración de estos micronutrientes extraídos con EDTA y con un método secuencial. Para esto se seleccionaron cuatro suelos con distinta intensidad de uso en los que se determinó el contenido pseudototal de estos elementos y su concentración con un método simple (EDTA) y de extracción secuencial (BCR). Los contenidos promedios pseudototales de Cu, Fe, Mn y Zn fueron: 14,4; 14010; 757 y 58,9 mg kg-1 respectivamente. Los niveles extractables con EDTA fueron: 4,4; 174,8; 410,6 y 8,4 mg kg-1, respectivamente. Los niveles de Cu estimados por ambos métodos fueron similares mientras que BCR extrajo mayores contenidos de Fe, Mn y Zn. La mayor parte del Fe, Zn y Cu se encontró en la fracción residual. Alrededor del 30% del Cu está disponible en la fracción oxidable y ligada a la materia orgánica. El Zn se asoció fundamentalmente a la fracción residual y en menor medida a formas intercambiables, oxidables y reducibles. El Mn está principalmente en la fracción reducible y en la fracción soluble en agua-ácido e intercambiable. Los resultados confirman que en estos suelos la disponibilidad de todos los micronutrientes ?determinados con EDTA? se encuentran por encima de los valores críticos.The objectives of this study were to determine the pseudototal and available contents of Cu, Fe, Mn and Zn as well as their speciation in Argiudolls located in the flat Argentine Pampas, in Santa Fe province, and to compare the contents extracted by EDTA with those by a sequential method. Four soils with different soil use intensity were selected for the study. Pseudototal micronutrient contents were determined and their concentrations were estimated by simple (EDTA) and sequential (BCR) extraction methods. The pseudototal average contents of Cu, Fe, Mn and Zn were: 14.4; 14010; 757 and 58.9 mg kg-1, respectively. The EDTA extractable levels were: 4.4; 174.8; 410.6 and 8.4 mg kg-1, respectively. The concentrations of Cu estimated by both methods were similar while higher contents of Fe, Mn and Zn were estimated by the BCR method. Iron, Zn and Cu were mainly found in the residual fraction. About 30% of total Cu was available in the oxidizable fraction and bound to soil organic matter. Zinc was primarily associated with the residual fraction and to a lesser degree to exchangeable, oxidizable and reducible forms. Manganese was mostly linked to the reducible, water-acid soluble and exchangeable fractions. These results confirm that in these soils the availability of all micronutrients determined by the EDTA method are above the critical values for crop growthFil: Carrizo, Maria Eugenia. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alesso, Carlos Agustín. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nascimento Guedes, Jair Do. Universidade Federal Rural Do Rio de Janeiro; Brasil;Fil: Imhoff, Silvia del Carmen. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Absorção de bário por plantas de arroz (Oryza sativa L.) e mobilidade em solo tratado com baritina sob diferentes condições de potencial redox

Two parallel tests were carried out to evaluate barium solubility in soils treated with barite under reducing conditions: one in leaching columns and another with potted plants cultivated with rice. Soils were treated with three doses of barite and kept at two humidity levels. The reduction (-200 mV) condition promoted an increase in barium in the geochemical fraction of higher liability, higher concentrations of barium in the leached extracts, and higher absorption by rice plants. As a result of increased uptake and accumulation of barium, the plants showed stunted growt

Concentração de metais pesados em espécies arbóreas utilizadas para revegetação de área contaminada Heavy metals concentration in tree species used for revegetation of contaminated area

O objetivo deste trabalho foi avaliar o potencial das espécies arbóreas Cordia africana Lam.,Mimosa caesalpineafolia Benth., Acacia angustissima (Mill.) Ktze. e Anadenanthera colubrina (Vell.) Brenan na fitoestabilização de metais pesados presentes em um substrato contaminado. Foram selecionados, aleatoriamente, quatro exemplares de cada espécie para realização do estudo. Amostras de substrato na projeção da copa de cada exemplar arbóreo foram coletadas nas profundidades de 0-10; 10-30 e 30-50 cm, para determinação da concentração pseudototal e fracionamento químico de metais pesados. De cada indivíduo, foram coletados dados referentes à profundidade das raízes, DAP (diâmetro a altura do peito), diâmetro de copa e altura das plantas. Amostras de folha, caule, casca e raiz foram coletadas para determinação dos metais pesados zinco (Zn), manganês (Mn), cádmio (Cd), chumbo (Pb) e cobre (Cu) nas diferentes partes da planta. A concentração de Cd no substrato foi acima do valor de investigação definido pelo CONAMA (3,0 mg kg-1), evidenciando contaminação com esse elemento. Os maiores teores dos metais pesados foram encontrados na fração residual (F5), indicando baixa disponibilidade destes elementos no substrato. Com relação ao Cd, elevadas concentrações também foram encontradas na fração trocável F2, considerada uma fração em que os contaminantes se apresentam com certa mobilidade e biodisponibilidade. As espécies vegetais estudadas apresentaram desenvolvimento dentro dos padrões normais, mostrando tolerância a áreas contaminadas com Cd, que tendeu a se acumular nas raízes das plantas, com exceção da Córdia - africana.This study aims to evaluate the potential of tree species Cordia africana Lam.,Mimosa caesalpineafolia Benth., Acacia angustissima (Mill.) Ktze. and Anadenanthera colubrina (Vell.) Brenan in the phytostabilization of heavy metal from a substrate contaminated. Four specimens of each tree specie were randomly determined for evaluations. Substrate samples were collected in the projection of the canopy trees of each specimen at depths 0-10, 10-30 and 30-50 cm for determining pseudototal concentration and chemical fractionation of heavy metals.Were collected data on roots depth, diameter at breast height, canopy diameter and plant height for each specimen. Samples of root, stem, bark and leaf were collected for analysis of heavy metals zinc (Zn), manganese (Mn), cadmium (Cd), lead (Pb) and copper (Cu). The Cd concentration in the substrate was above the investigation value defined by CONAMA (3,0 mg kg-1), showing contamination with this element. However, the highest concentrations of other studied heavy metals were found in the residual fraction (F5), indicating low availability of these elements in the substrate. High concentrations of Cd were also found in the exchangeable fraction F2, which is considered a fraction in which contaminants are present with some mobility and bioavailability. The plants showed development within the normal patterns, showing tolerance to Cd-contaminated areas, which tended to accumulate in the roots, except in the Córdia - africana

Sorção de Cd e Pb nos solos da região do Médio Rio Paraíba - RJ, Brasil

RESUMO As concentrações de metais na solução do solo são reguladas, principalmente, pelos processos de sorção. Neste estudo foi avaliada a dinâmica de sorção de Cd e Pb em 19 amostras de solos da Região do Médio Rio Paraíba - RJ, Brasil, através da comparação dos parâmetros de diferentes modelos de isotermas obtidos pelo software ISOFT após ensaios de sorção pelo método da batelada. Os resultados mostraram que a isoterma Linear é mais adequada para representar a sorção de Cd e o modelo de Freundlich para Pb e que a adsorção de Cd é fortemente influenciada pelo pH e pelas concentrações de Fe e Ca, enquanto que a adsorção de Pb é mais influenciada pelo pH, e pelas concentrações de Mn e Ca

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora