Biodisponibilidade de cromo em espécies vegetais de sistema várzea-estuário na região dos igarapés Piraíba e Anani. Distrito de Icoaraci, Belém-PA

Abstract

In the present work we studied the soil and vegetation of the Píraíba and Anani streams, located in the floodplain-estuary-mangrove system of Furo do Maguari (Icoaraci/Belém) and receptors of local lumber and tannery activities, with the following objectives: 1) To determine the levels of exchangeable and non-exchangeable chromium in sediments adhered to the roots and soils; 2) To determine the chromium levels in the leaves and roots of plant species. Samples were collected at four points of the Píraíba stream and at three points of the Anani stream, where soil samples were taken and plant species: Euterpe oleracea Mart. (açaí); Montrichardia arborescens L. (anínga) and Crinum undulatum. Measurements of hydrogen potencial (pH) and redox potential (eH) were made for soil samples at depths: 0-2, 2-5, 5-10cm and at 10cm intervals up to 1m depth in order to characterize the geochemical environment. The Cr analyses are in progress. In the Píraíba stream it is the superficial layers (2 to 20 cm) that present more acidity, while in the Anani stream the acidity increases in depth. The soil profiles of Piraíba creek are in general reduced, and oxidized only in the superficial layers. Point three presented the lowest Eh values. The Anani stream presented a differentiated behavior. For near the mouth (point 1) the environment is reducing, while near the lumber mill the environment becomes oxidizing in depth.