Dry Sand Quality: The Case Study of a Touristic Beach from Rio de Janeiro, Brazil

Abstract

Coastal contamination became a growing public health concern. Enteric illness outbreaks, and the occurrence of dermatitis and mycoses during the summer season in leisure areas, were usually related to seawater pollution. Pathogenic microorganisms can reach coastal areas through sewage discharges, compromising marine water, and beach quality. Although sand transmission of enteric illness is still unclear, there is an expressed concern that sand may act as reservoirs or vectors for humans infection. In this context, the main hypotheses of this study were: (i) fecal coliforms density changes within beach compartments; (ii) dry sand is the most contaminated beach compartment; (ii) fecal coliforms densities are within international standard limits for sand. Therefore, this case study quantified and compared within three months total fecal bacteria (TC) and thermotolerant coliforms (TEC) densities in seawater, wet, and dry sand of a chosen touristic beach from Rio de Janeiro, Brazil. Furthermore, to contribute to coastal beach management, sand contamination data surveyed were compared with the standard limits ruling worldwide until April 2018 to check suitableness. Vermelha beach should be considered as a reference beach for sand monitoring in Brazil. Despite being a buffer zone from the MONA Pão Açucar conservation unit, it is subjected to intense touristic pressure. Even though, fecal bacteria densities quantified in Vermelha beach were within the standards of “excellent” quality sand and water according to current legislation/guidelines. However, dry sand was the most contaminated compartment, followed by seawater and wet sand. The bacterial density in dry sand was up to 4,600 times higher than wet sand. Except for Rio de Janeiro city, recreational guidelines for beach quality is exclusive for seawater contamination. There are no established parameters for recreational beach sand classification, only recommendations, including Portugal. Monitoring recreational beach dry sand is critical to reducing the risk of beachgoer exposure to pathogens.