Caraterização granulométrica dos sedimentos do fundo no EBS utilizando análises de parâmetros estatístico diagramas de Pejrup e Shepard

Abstract

Sediments are important deposits of heavy metals, minerals of varying sizes, reservoirs and potential sources of pollutants for the water column. The concentration of these substances at the bottom of the estuary is directly controlled by the granulometric degree of the sediments in the environment. The main objective of this research was to characterize the sedimentary texture and hydrodynamics of the Bons Sinais Estuary, using statistical parameter analyses and Pejrup and Shepard diagrams proposed by Folk and Ward (1957). Fifteen sediment samples were collected from the bottom, using a sampler designed at ESCMC. To obtain the results presented, they were subjected to granulometric analyses in the civil engineering laboratory of ISHCT-Quelimane using the dry sieving technique. In the textural class, the sediments present are divided into three classes, with distinct depositional characteristics classified as sand, silt and clay, with sand being the most predominant. It is concluded that the average diameter of the Bons Sinais Estuary revealed a predominance of fine and very fine sand, coarse silt, very fine silt and medium silt. Regarding selection, the sediments of the estuary were classified as moderately selected and poorly selected, with negative and very positive asymmetry curves and positive symmetric curves associated with a high rate of coarse sediments. The amount of fine sediments is considerable, evidencing the possibility of the estuary being susceptible to the retention of pollutants. The granulometric distribution of the Bons Sinais Estuary presents characteristics of an environment with moderate and high hydrodynamics, probably due to the high tidal regime and the shallow depth of the estuary. The results of this study can serve as a starting point for future studies related to sediment dynamics and the distribution of pollutants along the estuary.