Comprehensive risk assessment and interactions of fluoride and boron ions in the water-sediments interface: The Red Sea, Egypt

Abstract

This study presents a baseline evaluation of the distribution, human and ecotoxicological risk, and the potential interactions of fluoride and boron in the water-sediment interface in 25 locations from incredible Red Sea tourist destinations. Results showed comparable levels of B and F in the water and sediments with previous literature. Significant positive correlation was found between B and F (r = 0.57; P<0.01). Based on the sediment/liquid partition coefficient (K_d), F is more likely to be released from the sediment into seawater (logK_d< 3) than B (3< logK_d< 4). pH and alkalinity may affect water-sediment interactions of B and F, respectively, while SO₄^2- and Cl^- ions had no significant effect on adsorption ability of F and B. The majority of minerals had average saturation Index (SI) > 1 referring to the over saturation of seawater with these minerals and their inability to dissolve. The formation of CF, FAP, and CFAP may be related to the high correlation between F_w (r = 0.928, P< 0.01; r = 0.527, P< 0.01; r = 0.608, P< 0.01) and B_w (r = 0.38, P< 0.05; r = 0.38, P< 0.05; r = 0.397, P< 0.05). Total hazard quotient (THQ) for children and adults were <1, revealing no health risks from exposure to B and F through ingestion and skin contact while swimming. The risk characterization ratio; RCR_{mix(MEC/PNEC)} showed high short-term risks to aquatic organisms. Further investigations might emphasis on emerging mitigation strategies to address these concerns.

Keywords: Boron and fluoride; Ecotoxicological and human risks; Red Sea; Saturation index; Seawater and sediment samples.