Distribuição da sílica biogénica nos sedimentos intertidais do estuário dos bons sinais, na província de Zambézia

Abstract

Biogenic silica (BSi) is an essential nutrient for certain primary producers, mainly diatoms, they use for the formation of their skeleton, their availability with other main nutrients contribute to the quality of the phytoplankton community. It is necessary to study the biogenic silica in the estuary of the Bons Sinais to know how it is distributed along the estuary. The present study, which aims to study the distribution of biogenic silica in intertidal sediments, was carried out in the Bons Sinais estuary, located in Quelimane in the province of Zambézia in December 2018. The experimental design consisted of sediment collection during a live tide at four sampling points along the estuary of the Bons Sinais, namely Municipal Sewage, Nhambire, Karungo and Ilalane. Each sediment sampling was done with three replicates for each point. Subsequent analyzes were carried out in the laboratory of Chemistry of Eduardo Mondlane University, where the concentrations of biogenic silica were determined in the sediments using the method described by DeMaster (1981). The results show that the highest concentration of biogenic silica was observed in Ilalane (464.0 mg / l), upstream and lowest in municipal sewage (172.0 mg / l). The ANOVA test showed a significant difference among the sampling points (p <0.05). These results suggest that the greatest contribution of silica to the sediments of the Bons Sinais estuary comes from "denser mangrove forests upstream" or river discharges because the largest source of silica is from the earth's origin