Antonio Rodrigues Fernandes

Assessment of risk to human health from simultaneous exposure to multiple contaminants in an artisanal gold mine in Serra Pelada, Pará, Brazil

Contamination of soil, water and plants caused by gold mining is of great societal concern because of the risk of environmental pollution and risk to human health. The aim of the present study was to evaluate the risk to human health from ingestion of As, Ba, Co, Cu, Cd, Cr, Ni, Pb, Se and Ni present in soil, sterile and mineralized waste, and water and plants at a gold mine in Serra Pelada, Pará, Brazil. Samples of soil, sterile and mineralized waste, water and plants were collected around an artisanal gold mine located in Serra Pelada. The mean concentrations of potentially toxic elements in the soil were higher than the soil quality reference values as defined in the legislation, which may be attributeable to past mining activities. Water from the area close to the mine exhibited As, Ba and Pb concentrations exceeding the reference values established by the World Health Organization, deemed unfit for human consumption. Plants exhibited high Pb concentrations, representing a food safety risk to the population. The mean hazard index (HI) values were below the acceptable limit (1.0) established by the United States Environmental Protection Agency, although the highest HI values observed for adults and children were higher than the respective acceptable limits. Environmental contamination and risk to human health were heterogeneous in the surroundings of the mine. Mitigation strategies need to be adopted to decrease the risks of contamination to the environment and to the local population.

Distribution coefficients of potentially toxic elements in soils from the eastern Amazon

The solid-solution distribution or partition coefficient (Kd) is a measure of affinity of potentially toxic elements (PTE) for soil colloids. Kd plays a key role in several models for defining PTE guideline values in soils and for assessing environmental risks, and its value depends on edaphic and climatic conditions of the sites where the soils occur. This study quantified Kd values for Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn from representative soil samples from Brazil’s eastern Amazon region, which measures 1.2 million km2. The Kd values obtained were lower than those set by both international and Brazilian environmental agencies and were correlated with the pH, Fe and Mn oxide content, and cationic exchange capacity of the soils. The following order of decreasing affinity was observed: Pb > Cu > Hg > Cr > Cd ≈ Co > Ni > Zn.

Impacts of different management systems on the physical quality of an Amazonian Oxisol

The physical quality of Amazonian soils is relatively unexplored, due to the unique characteristics of these soils. The index of soil physical quality is a widely accepted measure of the structural quality of soils and has been used to specify the structural quality of some tropical soils, as for example of the Cerrado ecoregion of Brazil. The research objective was to evaluate the physical quality index of an Amazonian dystrophic Oxisol under different management systems. Soils under five managements were sampled in Paragominas, State of Para: 1) a 20-year-old second-growth forest (Forest); 2) Brachiaria sp pasture; 3) four years of no-tillage (NT4.); 4) eight years of no-tillage (NT8); and 5) two years of conventional tillage (CT2). The soil samples were evaluated for bulk density, macro and microporosity and for soil water retention. The physical quality index of the samples was calculated and the resulting value correlated with soil organic matter, bulk density and porosity. The surface layers of all systems were more compacted than those of the forest. The physical quality of the soil was best represented by the relations of the S index to bulk density and soil organic matter.

Características químicas de um Gleissolo sob diferentes sistemas de uso, nas margens do rio Guamá, Belém, Pará

Foram estudados os efeitos do uso do solo sobre a fertilidade, em Gleissolo sob tres diferentes sistemas de manejo. As coletas foram feitas antes do periodo chuvoso nos seguintes sistemas de manejo: area cultivada com arroz (Oriza sativa L.) ha aproximadamente 40 anos, com algumas interrupcoes ao longo deste periodo, com o cultivo algumas vezes mecanizado e uso de aracao e gradagem; area sob pastagem de canarana erecta lisa (Echinochloa pyramidalis Hitch.), formada ha cerca de 20 anos sem uso de adubacoes ou calagens; e area sob vegetacao natural de floresta tipica das areas de varzea alta. As amostras de solo foram coletadas em dez pontos a partir de um transecto nas areas, em quatro profundidades 0-10, 10-20, 20-30 e 30-40 cm. Os resultados demonstraram que o solo em condicoes naturais, de modo geral, apresentou atributos quimicos que variaram de bons a muito bons, o que demonstra um grande potencial para o uso agricola. O cultivo agricola dos solos das varzeas do rio Guama provocou uma reducao da concentracao de P e de K. O sistema de uso com pastagem apresentou maior sustentabilidade da fertilidade do que o sistema sob cultivo com arroz, visto que, alem da melhoria das caracteristicas quimicas, a materia orgânica elevou-se, tambem, em relacao ao sistema natural.

Potentially toxic elements (PTEs) in soils from the surroundings of the Trans-Amazonian Highway, Brazil

The Trans-Amazonian Highway (TAH) is located in the northern region of Brazil, comprising a border region where agricultural, mining, and logging activities are the main activities responsible for fostering economic development, in addition to large hydroelectric plants. Such activities lead to environmental contamination by potentially toxic elements (PTEs). Environmental monitoring is only possible through the determination of element contents under natural conditions. Many extraction methods have been proposed to determine PTEs’ bioavailability in the soil; however, there is no consensus about which extractor is most suitable. In this study, we determined the contents of PTEs in soils in the surroundings of TAH after mineral extraction with diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), Mehlich I, and Mehlich III solutions. Soil samples were collected in areas of natural vegetation in the vicinity of TAH in the state of Pará, Brazil. Chemical attributes and particle size were determined, besides concentrations of Fe, Al, Mn, and Ti by sulfuric acid digestion, Si after alkaline solution attack, and poorly crystalline Fe, Al, and “free” Fe oxides. Mehlich III solution extracted greater contents from Fe, Al, and Pb as compared to Mehlich I and DTPA-TEA and similar contents from Cd, Mn, Zn, and Cu. Significant correlations were found between concentrations of PTEs and the contents of Fe and Mn oxides as well as organic carbon and soil cation exchange capacity. Contents of Cu, Mn, Fe, and Zn by the three methods were positively correlated.

Deficiências nutricionais de macronutrientes e sódio em mudas de pupunheira

The peach palm (Bactrisgasipaes Kunth) cultivation has increased according to increasing demand of its products; however there are few studies, as well as knowledge about nutritional requirement of this specie. The objective was to evaluate the nutritional symptoms deficiencies, dry matter production, nutrient content and accumulation in peach palm seedlings, according to macronutrients and Na omission. The experiment was realized in greenhouse in randomized blocks design. The treatments were: complete nutrient solution; omission of N, P, K, Ca, Mg, S and Na. The omissions promoted morphological alterations in shoots and roots characterized by visual symptoms easily interpretable. The elements N, P and K were the most limiting and the S and Na were the least limiting to leaves, stem, roots, shoots and total dry matter. The shoot/root relationship was K>Mg>Ca=P and P=complete=S=Na>N and the relative growth was complete>Na>S>Ca>Mg>K>P>N. The nutrient contents and accumulations follow mainly the sequence N>K>Ca>P>Mg>S>Na. The omissions caused symptoms typical to those observed in other species. The dry matter and relative growth were most limiting by N, P and K. The K, Mg, Ca and P were most limiting to roots and others nutrients were most limiting to shoots. The Na was important to peach palm, in the absence of Na of growth on reduced 10.6%. The nutrients in higher amounts in the specie are N, K and Ca.

Grasses and legumes as cover crop in no-tillage system in northeastern Pará Brazil

ABSTRACT Studies to select one or more species of coverage plants adapted to Amazonian soil and climate conditions of the Amazon are a promising strategy for the improvement of environmental quality, establishing no-till agricultural systems, and thereby reducing the impacts of monoculture farming. The aim of this study was to assess the persistence time, half-life time, macronutrient content and accumulation, and C:N ratio of straw coverage in a Ultisol in northeastern Para. Experimental design was randomized blocks with five treatments and five replicates. Plants were harvested after 105 days, growth and biomass production was quantified. After 84 days, soil coverage was 97, 85, 52, 50, and 15% for signalgrass ( Brachiaria brizantha ) (syn. Urochloa ), dense crowngrass ( Panicum purpurascens ), jack bean ( Canavalia ensiformes ), pearl millet ( Pennisetum americanum ) and sunn hemp ( Crotalaria juncea, ), respectively. Signalgrass yielded the greatest dry matter production (9,696 kg ha

Dris calculation methods for evaluating the nutritional status of oil palm in the Eastern Amazon

ABSTRACT This study aimed to evaluate six Diagnosis and Recommendation Integrated System (DRIS) calculation methods, including two ways to choose the nutrient ratio [F (Letzsch) or R (Nick) values] combined with three functions (Beaufils, Jones, or Elwali and Gascho), and to generate nutritional diagnoses for oil palm. A total of 144 foliar samples in 33 plots in the Eastern Amazon, Brazil, were used. Except for potassium (K) in all calculation methods, the DRIS indices showed no correlation with soil nutrients. Regardless of the formula, the nutritional balance index correlated with the productivity (significant r values) and similar diagnostics were obtained. These diagnoses were reliable according to the chi-square test (χ2), and most observed frequencies presented χ2 calculated less than χ2 tabulated. The average frequencies of samples with nutrient deficiency were 51%, 42%, 37%, 35%, 32%, 30%, 30%, 25%, 20%, 12%, and 12% for samples with nitrogen (N), boron (B), manganese (Mn), sulfur (S), K, copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), phosphorus (P), and magnesium (Mg), respectively. All tested DRIS methods may be used, and their diagnoses indicate the most common nutritional deficiencies in oil palm.

Maximum Phosphorus Adsorption Capacity Adjusted to Isotherm Models in Representative Soils of Eastern Amazon

Most soils of the Amazon present low natural fertility and may also present high phosphorus (P)–fixation capacity. Clay fraction mineralogy, organic carbon, cation exchange capacity (CEC), and pH are among the factors that influence P adsorption. In this study, we aimed to evaluate the maximum P-adsorption capacity (MPAC) and correlate parameters of the isotherm models and the MPAC with soil attributes. Soil samples were collected in 12 forest soils in the state of Pará. We built Langmuir and Freundlich isotherms, and their parameters correlated with soil attributes. MPAC was greater in Plinthosols, among the soils studied at both depths. In superficial soil layers, the parameters of Langmuir-Freundlich equations correlated with clay content, pH, organic matter (OM), aluminum oxide (Al2O3), and iron oxide (Fe2O3) at both depths. The Langmuir model is more representative of the adsorption of P relative to the Freundlich model for the Amazon region soils, where it is necessary to make use of organic matter and pH control as a means of reducing the retention and P and maximize the effects of fertilization phosphate.

Soil attributes under different crop management systems in an Amazon Oxisols

Soil biological properties have a high potential for use in assessing the impacts of crop systems. The objective of this study is to evaluate the effects of cropping systems on the biological attributes of an oxisol in the Amazonian state of Para. The treatments consisted of approximately 20-year-old secondary vegetation, recovered pasture, no-tillage systems (NT) maintained for 4 and 8 years after planting with corn (Zea mays L.) and soybean (Glycine max L.), and conventional tillage (CT) systems every 2 years after planting with rice (Oryza sativa L.) and soybean. The microbial biomass to nitrogen ratio was higher in the NT system (0.68 mg kg–1), and the NT system had greater microbial NT8. Thus, the contributions of organic matter from straw improved the soil quality in these areas. The total organic carbon (TOC) content was greater in the secondary forest and CT areas (46.7 and 48.0 mg kg–1, respectively), potentially due to the higher amounts of organic matter and organic matter mineralization in these areas. However, the largest TOC stocks were observed in the pasture, which corresponded with greater carbon storage (63.5 Mg ha–1). By contrast, the no-till systems were not efficient for storing C, with concentrations of 5.0 and 5.3 Mg ha–1 in NT-4 and NT-8, respectively. These results may reflect the short period that these systems were adopted and the vast microbial activity that was observed in these areas, with microbial quotients of 8.03 and 10.41% in NT-4 and NT-8, respectively.