Chemical attributes of archaeological black earth soils in Brazilian Amazon

Abstract

The substrate of Archaeological Black Earth (ABE) in archaeological sites is characterized by presence of anthropogenic A horizon that contains ceramic fragments and lithic artifacts of indigenous pre-Columbian origin. The aims of this study were to evaluate modification of chemical attributes of soils promoted by anthropic activities carried out in areas around archaeological sites soils in Northeast Pará Islands region. The study areas were located in Barcarena city (Alunorte site), Abaetetuba city (Bittencourt site), and Moju city (Jambuaçu site), State of Pará, Brazil. The experimental design was performed using randomized block design in situ with a collection of 7 ABE profiles at Alunorte site; 12 ABE profiles samples at the Bittencourt site and 6 ABE profiles samples at Jambuaçu site. The soil chemical attributes such as pH, C, OM, N, C/N, Na, K+, Ca+ 2, Mg+ 2, SB, Al+ 3, H+Al, CECef, %V, %m and P data were subjected to Tukey's test and to multivariate analyzer for principal component and cluster analysis. Jambuaçu site contained higher carbon, organic matter, magnesium, sum of bases, potential acidity, cation exchange capacity and phosphorus values compared to Bittencourt and Alunorte sites. Bittencourt site has characteristics such as pH, potassium, calcium and saturation consistent basis with values observed in ABE soils, while Alunorte site has no chemical characteristics like ABE features. Principal component analysis showed that variables such as organic matter and cation exchange capacity were most distinct among the archaeological sites soils (Alunorte, Bittencourt and Jambuaçu site).