~7.5 - 8.5 unitless
|Hopkinson, B.M., 2014. A chloroplast pump model for the CO2 concentrating mechanism in the diatom Phaeodactylum tricornutum. Photosynthesis research 121, 223-233 p.230 left column bottom paragraph
|Heldt HW, Werdan K, Milovancev M, Geller G (1973) Alkalization of the chloroplast stroma caused by light-dependent proton flux into the thylakoid space. Biochim Biophys Acta 314: 224–241 AND Anning T, Nimer N, Merrett MJ, Brownlee C (1996) Costs and benefits of calcification in coccolithophorids. J Marine Syst 9: 45–56 link PubMed ID4747067
|Primary source Heldt et al., abstract: "From the uptake of dimethyloxazolidinedione and of methylamine into the sucrose-impermeable space of intact spinach chloroplasts as measured by siliconlayer filtering centrifugation and from estimation of the size of the thylakoid space by planimetry of electron micrographs the pH in the stroma and in the thylakoid space is evaluated. The reliability of the method is checked." Primary source Anning et al., abstract: "Measurements of the cytosolic and intra-coccolith vesicle pH and electrical potentials across the plasma membrane and coccolith vesicle membrane allow calculations of the proton electrochemical gradients across these membranes and estimates of the free carbonate and calcium concentrations in the coccolith vesicle."
|P.230 left column bottom paragraph: "This pH is within the range of measured stromal pH values (~7.5–8.5) in plants and algae (primary sources)."