Fig. 2: Spatial variation in groundwater δ18OPO4 values and redox-sensitive components along the flow path. | Communications Earth & Environment

Fig. 2: Spatial variation in groundwater δ18OPO4 values and redox-sensitive components along the flow path.

From: Microbial cycling contributes to the release of dissolved inorganic phosphate into the groundwater of floodplain aquifers

Fig. 2

a Observed δ18O isotope values of groundwater (δ18OH2O). b Observed δ18O isotope values of dissolved inorganic phosphate in groundwater (δ18OPO4). c Calculated theoretical equilibrium δ18OPO4 values of dissolved inorganic phosphate after intracellular microbial cycling (δ18OPO4 equ). d Difference between observed δ18OPO4 and δ18OPO4 equ values (Δ18OPO4) (Negative Δ18OPO4 values indicate that observed δ18OPO4 were isotopically lighter (i.e. more 18O-depleted) than the calculated equilibrium δ18OPO4 equ values). e Redox potential (Eh) of groundwater. f–h Concentrations of dissolved inorganic phosphate (PO4), ferrous iron (Fe(II)), and sulfide (S2-), respectively. The blue, green and red rectangles showed the ranges of the alluvial fan, the transition area and the flat plain, respectively. Results of statistical analyses are shown in Fig. 3.

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