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For sustainable production systems, the nonuse of fire (where there is a greater loss of soil nutrients), would be a solution for the conservation of nutrients in the soil, with the use of management by cutting and grinding, introduction of AFSs (agroforestry systems), and maintenance of riparian vegetation. The concentrations of carbon and nutrients were evaluated in the soil solution in two small hydrographic basins in the municipality of Igarapé-Açu (Pará state) in the eastern Amazon region, Brazil. The evaluations were performed considering the biogeochemical cycling in six land-use classes—riparian forest, secondary forest (capoeira), pasture, slash-and-burn agriculture, chop-and-mulch agriculture, and an agroforestry system (AFS). The objective was to determine the effects of different land-use systems on the composition of the soil solution, aiming to recommend sustainable practices. The concentrations of nutrients were greater in the areas of slash-and-burn agriculture and pasture, indicating greater losses of these nutrients due to runoff and leaching. The loss of nitrate was highest in the slash-and-burn area, while the organic carbon and organic nitrogen losses were greatest in the riparian forest, then in the secondary forest and agroforestry areas.

RESUMO A representatividade da amostragem é fundamental para embasar a tomada de decisão, uma vez que a heterogeneidade da matriz é o principal fator para incerteza dos dados nos estudos de gerenciamento de áreas contaminadas. Neste estudo, coletaram-se 112 amostras de solo superficial em malha quadrada de 1 x 1 m, em uma área 15 x 6 m, no campus regional de Resende da Universidade do Estado do Rio de Janeiro. Anteriormente, no terreno funcionaram empresas de produção de filmes radiográficos e purificação de prata metálica. As amostras de solo foram analisadas por pXRF, método de screening para metais. Com base nos dados levantados, calculou-se, por meio de métodos estatísticos, a quantidade de amostras que permitiriam uma caracterização representativa da área, considerando um erro relativo de 20% para dois intervalos de confiança: 95 e 80%. As análises indicaram concentrações superiores aos valores de referência para os parâmetros prata, mercúrio, chumbo, selênio e zinco. Os resultados de mercúrio possivelmente referem-se a ruído espectral, não estando relacionados ao histórico de uso e ocupação. Os coeficientes de variação das concentrações dos elementos analisados variaram de 132 a 225%. Considerando uma distribuição lognormal, calcularam-se 76 amostras para o maior intervalo de confiança e 53 para o menor. Isso seria o equivalente a transectos com espaçamentos de 1,47 e 2,11 m. Os resultados ratificam a necessidade de investigações de alta resolução nas áreas fonte, conforme recomendado pela Decisão de Diretoria da Companhia Ambiental do Estado de São Paulo nº 038/2017/C (DD-038). ABSTRACT The representativeness of the sampling is fundamental to support decisions, since the heterogeneity of the matrix is the main factor for data uncertainty in contaminated areas management studies. In this study, 112 surface soil samples were collected in a square mesh of 1 x 1 m, in an area of 15 x 6 m, at the Campus Regional de Resende (CRR) of Universidade do Estado do Rio de Janeiro (UERJ). Previously, companies of radiographic films production and metallic silver purification operated in this area. The soil samples were analyzed by pXRF, a screening method for metals detection. Based on the data collected, the number of samples that would allow a representative characterization of the area was calculated, using statistical methods, considering a relative error of 20% for 80 and 95% confidence intervals. The analyses indicated concentrations higher than the reference values for the parameters silver, mercury, lead, selenium, and zinc. The results of mercury possibly refer to spectral noise, not being related to the history of use and occupancy. The coefficient of variation of the soil obtained ranged from 132 to 225%. Considering a lognormal distribution, 76 samples were calculated for the highest confidence interval and 53 for the lowest. This would be the equivalent of transects with spacings of approximately 1.47 and 2.11 m. The results confirm the need for high resolution investigations in the source areas, as recommended by the Executive Board Decision of CETESB No. 038/2017/C (DD-038).

Durante algo más de 50 años antropólogos, arqueólogos, linguistas y geógrafos se han ocupado seriamente del pasado de la Amazonia. Más recientemente otros académicos, entre ellos genetistas y ecólogos, se han fascinado por el mismo. Durante más de 10.000 años los nativos han participado e interpretado esta historia. una historia que unos y otros leen y descifran a partir de diversas claves, como lo pueden ser las formas del paisaje, algunos objetos antiguos y los testimonios y tradiciones orales que tienen a su alcance. Los resultados son múltiples. Estos revelan tanto desacuerdos entre los especialistas como mundos insospechados. Se hacen evidentes caminos que se cruzan y se mezclan; en una dirección convergen y en otra divergen. El lector encontrará en este volumen una fracción de este universo, la misma va acompañada de una invitación a participar en un diálogo amplio que contribuya a enriquecer nuestra visión de un mundo por explorar.

For sustainable production systems, the nonuse of fire (where there is a greater loss of soil nutrients), would be a solution for the conservation of nutrients in the soil, with the use of management by cutting and grinding, introduction of AFSs (agroforestry systems), and maintenance of riparian vegetation. The concentrations of carbon and nutrients were evaluated in the soil solution in two small hydrographic basins in the municipality of Igarapé-Açu (Pará state) in the eastern Amazon region, Brazil. The evaluations were performed considering the biogeochemical cycling in six land-use classes—riparian forest, secondary forest (capoeira), pasture, slash-and-burn agriculture, chop-and-mulch agriculture, and an agroforestry system (AFS). The objective was to determine the effects of different land-use systems on the composition of the soil solution, aiming to recommend sustainable practices. The concentrations of nutrients were greater in the areas of slash-and-burn agriculture and pasture, indicating greater losses of these nutrients due to runoff and leaching. The loss of nitrate was highest in the slash-and-burn area, while the organic carbon and organic nitrogen losses were greatest in the riparian forest, then in the secondary forest and agroforestry areas.