Pesquisa físico-química dos elementos do solo da região de Caxiuanã - PA

Abstract

The Ferreira Penna Scientific Station is located in the Caxiuanã National Forest (FNC), municipality of Melgaço, Pará. This area is a cradle of research in various areas of knowledge by both national and international institutions. In Caxiuanã several archeological sites have been found, where most of them have soils known as Terra Preta Arqueológica or Terra Preta do Índio. These soils have a black coloration, archeological material (pottery fragments and lithic material) and a high natural fertility, currently sought by riverbank dwellers for housing or cultivation. Physically, the texture of these soils is sandier and the structure stronger than the adjacent ones. The present work aims to make a comparative study of the chemical elements, Ca, Mg, Zn, Mn, P and C of the Terra Preta Arqueológica (TPA) with the adjacent areas (AD) found in the archeological soils and the classification of the shells occurring in the Caxiuanã region. Soils collected from the TPA's and AD's of the following sites were analyzed: Torrão, Caridade, Mina I, Tijucaquara, Flexal and Retiro. The soil samples were pulverized and passed through a 2 mm sieve and Ca, Mg, Mn and Zn were analyzed by EAA and P by Colorimetry. The Flexal site showed the highest values for almost all elements. The Ca contents in TP A were 4448 ppm and 752 ppm in AD; Zn and Mn varied from 77 and 1090 ppm in TP A to 39 and 213 ppm in AD, respectively; Phosphorus presented values of 2680 ppm in TPA and 1321 ppm in AD. The highest levels of Mg were found at the Retiro site, ranging from 839 to 317 ppm at TPA and AD, respectively. In all the archaeological sites analyzed the values found in the TPA's are significantly higher than the adjacent areas. The higher values found at the Flexal site may be due to the shell concentrations. For, at the f1exal and Ibama sites shell deposits of different species are found, of the bivalve type and fresh water environment.