First Attempt to Study Sedimentological Characteristics and Contamination Levels of Bottom Sediments in the Faanu Mudugau Blue Hole (Ari Atoll, Maldives)

Environmental contamination is ubiquitous and even in the ocean, signs of contamination of different types (chemical, biological, or plastic) are detected in all kinds of environments. In this study, a sediment core was sampled at the bottom of the Blue Hole of the Maldives (Ari Atoll) to make a first characterization of the sediment in terms of its grain size and organic–inorganic matter composition and to assess the sediment contamination levels in terms of trace elements (by ICP-MS analysis) and the eventual presence of microplastics (by optical classification and microRaman analysis of items). High concentrations of Hg (a maximum value of 0.145 ppm at the bottom layer of the core), Cd (a maximum value of 0.65 ppm at the core surface layer), and As (9.4 ppm at the top of the core) were highlighted at different layers of the sediment core. Plastic polymers were not detected in the sediment core, but 51 fibers characterized by the presence of artificial dyes or additives were found in the core (a mean of 5.7 fibers for each slice). The results confirmed the sediment contamination of the Maldivian Blue Hole, supporting the hypothesis of contamination due to ineffective waste management within the archipelago and mass tourism affecting the atolls.