Assessment of inorganic water quality in marine areas affected by an artificial beach nourishment: A case study in northeastern Brazil

This study examines the impact of an artificial beach nourishment project on seawater quality at two beaches in Fortaleza, Ceará, Brazil. The research was conducted between October 2019 and May 2022. Twenty-seven inorganic water quality parameters were analyzed in five phases: at the beginning, during execution and in three phases after completion of the works. The distribution of chemicals in the marine sediment was also analyzed. The water analysis showed that the average concentrations of four parameters were above the maximum permissible values (MPV) established by the Brazilian standard in at least one phase of the study. The fluoride concentration reached 2.4 mg/L, exceeding the MPV of 1.4 mg/L. Polyphosphates recorded a maximum value of 0.085 mg/L, exceeding the MPV of 0.031 mg/L, while hydrogen sulfide reached 0.0023 mg/L, exceeding the MPV of 0.0020 mg/L. Total residual chlorine showed average concentrations above the MPV of 0.01 mg/L in all phases of the study, with a maximum value of 0.64 mg/L. On the basis of this study, there is no concrete evidence that the concentrations above the MPV are due to the artificial beach nourishment, as these concentration peaks were not only observed in the samples taken during the execution phase of the work. Furthermore, no significant permanent changes in the physical and chemical properties of the water were detected after the end of the work. The statistical differences observed in the inorganic water quality parameters can be attributed to the marine dynamics in the region, such as strong currents, mixing of water masses and the tidal regime. In addition, the study area is influenced by various anthropogenic activities that can contribute significantly to these changes. The analysis of metals and nutrients in the sediment revealed concentrations below the limits established by the Brazilian standard.