Risk assessment of trace elements pollution of Manaus urban rivers.

Manaus is the Capital City of Amazonas State, Brazil, in the heart of the Amazon rainforest. Its metropolitan area has a huge hydrographic basin where the disorganized urbanization has caused adverse effects in the urban rivers and creeks water quality. Thus, this study was conducted to evaluate the contents of Ba, Cr, Mn, Zn, Ni, Cu, the physicochemical parameters and their respective health risks in water samples from rivers and creeks located in urban areas with different degrees of urbanization in two different seasons. The determination of the physicochemical parameters showed the samples collected in areas with riparian vegetation presented mean values of temperature, pH, total dissolved solids and electrical conductivity lower than samples collected in urban environment. The hotspots of trace elements content were associated to the presence of industrial and domestic effluents as the main pollution source. The Water Quality Index results denoted a low water quality in four sampling sites, one during the rainy season and three others during the dry season. The overall non-carcinogenic health in the urban rivers was considered high in regions with huge population and intense anthropogenic activity. The results showed the potential risk of some of the trace elements on human beings, especially on children. The main element contributor to non-carcinogenic risk was Cr, although Mn and Ni also contributed to non-carcinogenic risk in a few areas, mainly for children during the dry season.

Níveis críticos e faixas de suficiência nutricional em laranjeira-pêra na Amazônia Central obtidas pelo método DRIS / Critical levels and nutrient sufficiency ranges in orange of the Central Amazon determined by DRIS method

The nutritional status of orange trees depends of reference values that are appropriate to reflect their nutritional condition. The objective this work was to assess the nutrient reference values and evaluated the nutritional status of sweet orange trees in several orchard fields of Central Amazonia (municipalities of Iranduba, Manacapuru, Manaus, Presidente Figueiredo and Rio Preto da Eva). We used the Diagnosis and Recommendation Integrated System for multivariate relation (DRIS) method to establish the nutrient reference values. The nutritional status of 120 commercial orchards of orange grafted on rangpur lime was evaluated by the sufficiency ranges defined from the set of nutritionally balanced plants. For macronutrients, the nutritional sufficiency ranges were (g kg-1): 28-30 (for nitogen, N); 1.6-1.7 (phosphorus, P); 7-9 (potassium, K); 26-29 (calcium, Ca); 3.6-4.0 (magnesium, Mg); 1.7-2.0 (sulfur - S) and for micronutrients (mg kg-1): 47-56 (boron, B); 8-10 (copper, Cu); 84-93 (iron, Fe); 12-13 (manganese, Mn); 14-16 (zinc, Zn). For macronutrients, the critical levels were (g kg-1): 28 (for N); 1.6 (P); 7 (K); 26 (Ca); 3.6 (Mg); 1.7 (S) and for micronutrients (mg kg-1): 47 (B); 8 (Cu); 84 (Fe); 12 (Mn) and 14 for Zn. Nutritional standards obtained by the DRIS methods are in disagreement with the normal ranges proposed in the literature for most nutrients. In about 50% of orchards, the elements P, K, Ca, S, B, Cu e Fe were found below the critical levels. This suggests that orange producers in Central Amazonia should pay more attention to these elements when planning fertilization practices.

A avaliação do estado nutricional da laranjeira depende da definição de valores de referência que sejam adequados para refletir suas condições nutricionais. Neste trabalho, objetivou-se determinar os valores de referências e avaliar o estado nutricional de laranjeiras-pêra em diversas glebas na Amazônia Central (municípios de Iranduba, Manacapuru, Manaus, Presidente Figueiredo e Rio Preto da Eva). Utilizou-se o Sistema Integrado de Diagnose e Recomendação de relações multivariadas (DRIS) para estabelecer os valores de referência nutricional. O diagnóstico nutricional de 120 glebas comerciais de laranjeiras-pêra, enxertadas em limoeiro cravo foram avaliadas pelas faixas de suficiência definidas a partir do conjunto de plantas nutricionalmente equilibradas. Para os macronutrientes, as faixas de suficiência nutricional foram (g kg-1): 28-30 (para nitrogênio, N); 1,6-1,7 (fósforo, P); 7-9 (potássio, K); 26-29 (cálcio, Ca); 3,4-4 (magnésio, Mg); 1,7-2 (enxofre, S) e para os micronutrientes (mg kg-1): 47-56 (boro, B); 8-10 (cobre, Cu); 84-93 (ferro, Fe); 12-13 (manganês, Mn); 14-16 (zinco, Zn). Para os macronutrientes, os níveis críticos foram (g kg-1): 28 (para N); 1,6 (P); 7 (K); 26 (Ca); 3,6 (Mg); 1,7 (S) e para os micronutrientes (mg kg-1): 47 (B); 8 (Cu); 84 (Fe); 12 (Mn); 14 para Zn. Padrões nutricionais obtidos pelo DRIS discordam das faixas de suficiência propostas pela literatura para maioria dos nutrientes. Em quase 50% das glebas monitoradas, P, K, Ca, S, B, Cu e Fe estão abaixo dos níveis críticos propostos neste trabalho. Isto sugere que os produtores de laranja na Amazônia Central deveriam atentar-se para estes elementos no planejamento das fertilizações.

Fontes, doses e modos de aplicação de fósforo na interação fósforo-zinco em milho / Sources, dosages and manners of phosphorous application on phosphorous-zinc interaction in corn

No presente trabalho, objetivou-se avaliar a interação P-Zn no milho durante dois cultivos sucessivos, num Argissolo Vermelho típico , textura argilosa, na região do Cerrado. O delineamento experimental foi o de blocos casualizados com quatro repetições, num esquema fatorial 3x2x2+1, envolvendo três doses de P2O5 (180, 360 e 540 kg ha-1), duas fontes (superfosfato triplo - ST e fosfato natural reativo de Arad - FR), duas formas de aplicação (a lanço em área total e no sulco de plantio) e uma testemunha (sem P) como tratamento adicional. Determinaram-se o peso de matéria seca da parte aérea e de grãos, teores de P, Zn e relação P-Zn nas folhas e nos grãos. Os teores de Zn diminuíram com aplicação de ST no sulco, alcançando valores tidos como deficientes, no primeiro cultivo, sem contudo, afetar a produtividade do milho. Os teores de P, Zn e relação P-Zn nos grãos apresentaram-se dentro dos padrões adequados para o milho. A interação P-Zn nos tratamentos com ST no sulco de semeadura, talvez pela adubação prévia com Zn, não foi suficiente para afetar o rendimento de grãos do milho.

In the present work, the objective was to evaluate the interaction of P-Zn in corn during two successive cultivations, in a typical Red Argisol, loamy texture, in the area of the Savannah. The experimental layout was the one randomized blocks with four replications, in a 3x2x2+1factorial outline, involving three doses of P2O5 (180, 360 and 540 kg ha-1), two sources (triple superphosphate - ST and Arad phosphate rock - FR), two application manners (casting on the total area and in the planting furrow, both in the first year) and a control (without P) as an additional treatment. One determined the dry matter weight of the aerial part and of grains, levels of P, Zn and the relationship of P/Zn in the leaves and in the grains. The tenors of Zn were decreased with application of ST in the seed furrow, reaching values said as deficient, in the first cultivation, without affecting, however, the corn produtivety. The tenors of P, Zn and P/Zn relationship in the grains presented themselves within the normal standard for corn. The interaction P-Zn at treatments with ST in the planting furrow, maybe due to previous manuring of Zn, was not sufficient to affect the yield grain of the corn.