Reaction rates and δO18 variation for the carbonate-phosphoric acid preparation method

Stable Isotopic Investigation of Carbonate Samples Related to the Messinian Salinity Crisis from DSDP Leg 42A, Mediterranean Sea

“…In general, for carbonate mixtures in which the percent dolomite was between 20 and 50%, a chemical separation was undertaken during the phosphoric acid reaction to obtain CO 2 gas from both the calcite and the dolomite fractions (Epstein et al, 1964). The small particle size (5 to 10µ) was taken into consideration when determining the reaction times for the chemical separation (Walters et al, 1972).…”

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

“…In addition, carbon isotopes were measured in bitumens extracted from the ferromanganese nodules. Carbon and oxygen isotope measurements were carried out by fractionated extraction of carbon dioxide (Walters et al, 1972;AI-Aasm et al, 1990) with 103% phosphoric acid at 25°C/2 h for calcite, 25°C/2 days for dolomite, 25°C/2 days for rhodochrosite and 50°C/9 days for siderite. Isotopic ratios were measured in a SIRAII VG-Isotech mass spectrometer.…”

Carbonate removal from coastal sediments for the determination of organic carbon and its isotopic signatures, δ13C and Δ14C: comparison of fumigation and direct acidification by hydrochloric acid

“…HCl was chosen to carry out the aqueous method, because it is able to dissolve dolomite (Chang et al 1996). Concentrated phosphoric acid can also dissolve dolomite (e.g., Walters et al 1972), but is problematic because it produces highly viscous and hygroscopic condensation products upon drying. Sulfurous acid (6%) is too weak for efficient removal of dolomite (Nelson and Sommers 1982;McNichol et al 1994;Kennedy et al 2005), and commercially available solutions are a source of carbon contamination (McNichol et al 1994, Caughey et al 1995.…”