DISTRIBUIÇÃO E FRACIONAMENTO DE FÓSFORO EM SEDIMENTOS DE MANGUEZAIS DO ESTUÁRIO DO RIO TIBIRI NA ILHA DO MARANHÂO, REGIÃO AMAZÔNICA

Abstract

In order to assess the environmental impact and the behavior of phosphorus in the sediments of mangrove Tibiri River on the Maranhão island, five phosphorus fractions were determined (TP, IP, OP, AP) and NAIP in mangrove sediment, through sequential extraction according to the protocol of the European Commission (SMT - standards, measurements and testing Programme). Concentrations of the majority metals were also determined (Ca , Al , Mg , Fe and Mn) by inductively coupled plasma atomic with optic emission spectrometry (ICPAES) in the same extracts of cited above, moreover, mineralogical analysis of the mangrove sediment was made by X-ray diffraction. Sediments form Tibiri River showed phosphorus levels in the order of 341.44 mg.kg-1, characterized as an estuary with inexpressive impact of anthropogenic activities. Most phosphorus is found in the non-apatite inorganic fraction, (NAIP), mean 70%. The inorganic fraction of phosphorus, such as apatite mineral (PA) remained at 29%. Rio Tibiri was classified as unpolluted (PT < 500 mg kg-1), although most phosphorus is found as labile (mean 73.68%). Among the majority metals, Ca stood out by its association with the apatite fraction (AP), Corroboratig the presence of this mineral in the sediment. The main clay minerals found were kaolinite, montmorillonite , illite and quartz.