Fig. 8: Relationship between average arsenic concentrations in microbialite micrite and seawater across provinces of Hamelin Pool.
From: Arsenic enrichment patterns are defined by microbialite morphology, fabric, and accretion mechanism
A Laminated microbialites and sheet mats: yellow triangles show average arsenic concentrations in micrite from laminated discrete microbial buildups (DMB) collected from Carbla (n = 3), Nanga (n = 8), Flagpole South (n = 5), Flagpole North (n = 5), Booldah (n = 3), and Spaven (n = 3) provinces; the pink circle shows average arsenic concentrations measured in sheet mats collected from supratidal zones in the Nilemah province (n = 3). B Clotted microbialites: red squares show average arsenic concentrations in clotted discrete microbial buildups (DMB) from Hutchison (n = 2), Nanga (n = 2), Flagpole South (n = 6), and Flagpole North (n = 4) provinces. Error bars indicate standard deviations. Provinces were defined in a previous study32 and are shown in Fig. 7. Blue lines illustrate the predicted arsenic concentration in micrite as a function of seawater arsenic concentration when arsenic incorporation is primarily inorganic (Eq. 2), with the slope corresponding to EFinorg. Green line shows the predicted arsenic concentration in micrite as a function of seawater arsenic concentration, when arsenic is incorporated from both seawater (Eq. 2) and transfer from organic matter (Eq. 3). Shaded areas are 95% confidence intervals. Lower sub-panels show the expected contributions (%) from seawater (blue) and organic matter degradation (green) as a function of seawater arsenic concentrations.
