Analíse de parâmetros físico-quimicos para avaliação da qualidade da água do Estuário do espírito santo, Matola – Moçambique

Abstract

The Espírito Santo estuary, located in the city of Matola, on the western shore of Maputo Bay, is considered one of the most important ecosystems in Mozambique due to its biodiversity and fishing activity in its waters, which has a considerable impact on the country's economy. This scientific research work assesses the aquatic environment of the Espírito Santo estuary in Maputo province, Mozambique. The assessment was carried out by analysing the water, by quantitatively determining the physical and chemical parameters: pH, electrical conductivity, salinity, dissolved oxygen, temperature, turbidity, total hardness, calcium, magnesium, sulphates, total alkalinity and phosphates. The concentrations obtained from monitoring the parameters were compared with the limits established by the World Health Organisation (WHO) for estuarine waters and with values ​​from a previous study carried out in the dry season in the same estuary. The water samples from the Espírito Santo estuary showed concentrations above the limits recommended by the WHO for total hardness, Ca2+, Mg2+, sulfates, total alkalinity and phosphates. The parameters pH, EC, DO and Turbidity showed concentrations within the recommended limits. The values ​​obtained in this study show that the contamination levels during the dry season are above the levels during the rainy season at all points studied. The statistical calculations show that the precision of the results of the parameters analyzed in the Espírito Santo water samples ranged from very good to good, with % RSD values ​​between 0.00 and 4.7% for all parameters, with the exception of the parameters Mg2+ and phosphates, whose precision was low. The results obtained from this study allowed us to conclude that the water of the Espírito Santo estuary is polluted, with the highest level of pollution occurring in the dry season, and the estuary represents a risk to the life of aquatic species, which could affect their quality, quantity and even lead to their extinction. The estuary under study is also not suitable for carrying out some subsistence activities of human communities, such as the use of water to help remove dirt and in steam generating equipment.(TRADUÇÂO NOSSA)