Controls on the δ13C of dissolved inorganic carbon in marine pore waters: An integrated case study of isotope exchange during syndepositional recrystallization of biogenic carbonate sediments (South Florida Platform, USA)

Transformations of carbon in anoxic marine sediments: Implications from Δ14C and δ13C signatures

“…6c), but because the net reaction rate of DOC was low, this sink was insufficient to explain the high d 13 C DIC . Anomalously high d 13 C values have been reported for pore-water DIC for a number of systems (Walter et al 2007 and references therein), including nearshore terrigenous sediments (McNichol et al 1991). Walter et al (2007) propose that this is due to equilibrium 13 C exchange between DIC and PIC.…”

“…Anomalously high d 13 C values have been reported for pore-water DIC for a number of systems (Walter et al 2007 and references therein), including nearshore terrigenous sediments (McNichol et al 1991). Walter et al (2007) propose that this is due to equilibrium 13 C exchange between DIC and PIC. Hu and Burdige (2008) and Burdige et al (2010) provide a different mechanism where d 13 C DIC increases due to a combined effect of pore-water DIC precipitation and dissolution of 13 C-enriched metastable carbonates.…”

“…It has been shown through both field measurements and incubation experiments that isotope exchange between DIC and carbonates can occur under anaerobic conditions with limited or no net dissolution (Walter et al 2007;Hu and Burdige 2008). The exact mechanism of exchange is unclear, but proposed explanations include isotope exchange between CO 2 (aq) and carbonates with high specific surface areas (Walter et al 2007), and dissolution of metastable phases coupled with precipitation of more stable secondary phases (Hu and Burdige 2008;Burdige et al 2010). Here we adopt the coupled dissolution re-precipitation model of Hu and Burdige (2008; Fig.…”

“…Second, in contrast to the observed D 14 C PIC values which were notably depleted, the modelderived D PICm was enriched (+14%), suggesting a modern biogenic origin. Walter et al (2007) proposed that isotope exchange occurs between pore-water DIC and biogenic carbonates with high specific surface areas. As outlined in the Methods section, shell fragments were present in the incubated sediment, but were removed prior to powdering the samples for analyses to prevent bias.…”

The Marine Carbon System and Ocean Acidification during Phanerozoic Time

“…For example, the DIC of Florida Bay pore waters is significantly depleted in 13 C owing to respiration of organic matter in the sediments as compared to the DIC of adjacent open ocean surface seawater (Walter et al ., 2007) . The data accumulated by Walter et al .…”