Potential effects of heavy metal pollution from a cement factory near Saudi Arabia's largest green turtle rookery

Abstract

Sand samples were collected from four beaches near a cement factory in Ras Baridi, north of Yanbu, which hosts the largest green turtle rookery in Saudi Arabia. Heavy metal concentrations (Cd, Pb, Fe, Cr, Ni, Se, Sb, As, and Cu) were measured at three different depths. For most elements, there were no significant differences in concentrations among depths; however, significant differences were found among the nesting beaches in Ras Baridi, which were likely influenced by the wind direction from the factory. Fe, Cr, Cu, and Ni had elevated contamination factor values, suggesting that the nesting beaches downwind and adjacent to the cement factory contained moderately contaminated sand. Given the possibility of heavy metals being absorbed through eggshells, there is a potential risk of heavy metal contamination in clutches laid in Ras Baridi. The rising threat to the local ecology in Saudi Arabia due to recent coastal developments for tourism projects highlights the importance of monitoring heavy metal concentrations over time.

Keywords: Cement pollution; Endangered species; Environmental assessment; Red Sea; Sand contamination; Turtle nesting threats.

Fig. 1

A Sand samples for assessments of heavy metal concentrations were collected from two regions along the Saudi Arabian Red Sea, including Ras Baridi, the largest green turtle rookery in Saudi Arabia, and Rabigh, our reference nesting site (blue circles). We sampled four beaches at Ras Baridi, at varying distances from the Yanbu Cement Factory, including Upwind (green), Factory (red), Downwind 1 (yellow), and Downwind 2 (orange). B At each of the five beaches studied, four sampling stations were chosen, equally spaced apart. The small colored circles on map A represent the different sampling stations at each beach. At each sampling station, three collection points were selected 1 m apart from each other at 0, 30, and 50 cm depth, and homogenized by depth

Fig. 2

Average heavy metal and metalloid concentrations (mg/kg) ± standard error (se) of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), antimony (Sb), and selenium (Se) from four turtle nesting beaches, varying distances away from a cement factory near Yanbu, Saudi Arabia. All average concentrations are shown on the x-axis (note varying scale for each element). The locations of the four beaches are indicated on the right panel and include Upwind, Factory, Downwind 2, and Downwind 1

Fig. 3

Average heavy metal and metalloid concentrations (mg/kg) ± standard error (se) of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), antimony (Sb), and selenium (Se) from 3 depths, 0, 30, and 50 cm. These depths correspond to sand surface, and the average nest depth of hawksbill and green turtles, respectively. All average concentrations are shown on the left y-axis (note varying scale for each element), and the metals are identified on the right y-axis. Five nesting beaches on the Saudi Arabian Red Sea coast were sampled, including Rabigh Beach (the reference beach) and four beaches (Upwind, Factory, Downwind 1, and Downwind 2) located near the Yanbu Cement Factory in an area known as Ras Baridi

Fig. 4

Average heavy metal concentration ± standard error of As, Cd, Cr, Cu, Ni, Pb, Sb, Se, and Fe measured at turtle nesting sites in Saudi Arabia, including a site adjacent to the cement factory in Yanbu (red) and Rabigh Beach, our uncontaminated reference site (blue). An independent 2-group t-test revealed significantly higher concentrations of every element at the factory site compared to the Rabigh Beach site