Pee Dee Belemnite

Methods for pretreatment of samples for 13C analysis had been described in Chen et al. (2002a). After pretreatment, soil samples and plant debris were sent to the State Key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences (CAS), for 13C analyses. The 13C analyses were conducted using a Finnigan MAT-251 mass spectrometer manufactured by Finnigan-Mat Company, with a precision of 0.2%o. Results are reported as 513C, in parts per thousand of the 13C/12C ratio from that of the International Pee Dee belemnite (PDB) standard, where ... 

The equations for the isotope pairs 2H/1H, 13C/12C, and 34S/32S parallel the relations for 180/160, except that the reference species for carbon and sulfur are CO2 and H2S, rather than solvent water. Carbon and sulfur compositions are many times reported with respect to the PDB (Pee Dee belemnite) and CDT (Canyon Diablo troilite) standards, instead of SMOW. It makes little difference which standard we choose in applying these equations, however, as long as we carry a single standard for each element through the calculation. 

Vienna-Standard Mean Ocean WMer (V-SMOW) Vienna-Pee Dee Belemnite (V-PDB) air nitrogen PVIR-N2)... 

These delta values (read delta C-13 , or delta carbon-13 ) are typically given in parts per thousand ( permil , %o). For historical reasons, carbon stable isotopes are reported relative to the PDB (Pee Dee Belemnite, a fossil) or the equivalent VPDB (Vienna PDB) standard. Oxygen and hydrogen stable isotopes are reported relative to SMOW (Standard Mean Ocean Water) or the equivalent VSMOW (Vienna SMOW). The VPDB and VSMOW standards are preferred, not only because the original standards, PDB and SMOW, are no longer available, but also because they imply that the measurements have been calibrated according to international conventions. 

Carbon and hydrogen measurements were made on a Varian MAT 250 triple collecting MS and sulfur and nitrogen on a Nuclide RMS 6-60 dual collecting MS. Atmospheric N, Chicago Pee Dee belemnite, SMOW and Canyon Diablo troilite were used for isotope standard Analytical errors for isotope ratjp measurements were as follows 8 C 0.05 per mil, SD 3 per mil, 5 S 0.4 per mil, 5 N 0.4 per mil, and for elemental analyses, C 0.5%, H l%, S 0.5%, N 0.5%. 

Finally, the del value is zero when the sample and the standard have the same isotopic composition. The international standards for O, C, H, N, and S are Standard Mean Ocean Water (SMOW), Pee Dee Belemnite (PDB) carbonate fossil, SMOW, atmospheric nitrogen (N2), and the Canyon Diablo Triolite (CDT) iron meteorite, respectively (table 7.6 Fame, 1986). More specifically, the13C/12C of natural materials and standards is determined using isotope-ratio mass spectrometry (for details, see Hayes, 1983 Boutton, 1991). 

Stable carbon isotope ratios have been measured for a variety of samples of each type. Data are quoted as 513C values relative to the PDB standard (Pee Dee Belemnite) where... 

Stable oxygen and hydrogen isotopic ratios are normally reported relative to the standard mean ocean water (SMOW) standard (Craig, 1961b) or the equivalent Vienna-SMOW (V-SMOW) standard. Carbon, nitrogen, and sulfur stable isotope ratios are reported relative to the Pee Dee Belemnite (PDB) or Vienna-PDB (VPDB), ambient air (AIR), and Canyon Diablo Troilite (CDT) standards, respectively, as defined later. The use of the V before SMOW or PDB indicates that the measurements were calibrated on normalized per mil scales (Coplen, 1996). 

The units of are per mil (%o) and 5 0ct values are commonly reported relative to either the Standard Mean Ocean Water (SMOW) or the Pee Dee belemnite (PDB) standards (Craig, 1957, 1961), where S Osmow = 1.0308645 0pdb + 30.864. A similar expression to Eq. (4) defines C-isotope variations, with values always reported relative to the PDB standard. The values for water cited in this paper are given relative to the SMOW standard 5 0 values for calcite and all values are given relative to the PDB standards for oxygen and carbon respectively. 

The data are expressed as TR (Tritium Ratio 1 TR corresponds to a H/H ratio of 10 or to an activity concentration of 0.118 Bq/kg water). The data are expressed as percent modem carbon (pmc 100 pmc corresponds to 95% of the NBS oxalic acid standard or to an activity concentration of 0.226 Bq/g C). The and data are expressed as deviations(8-values) relative to SMOW (Standard Mean Ocean Water). The data are expressed as deviations relative to PDB (Pee Dee Belemnite) standard. The data are expressed as /qo deviations relative to CDT (Canion Diablo Troilite) standard. 

Similarly, carbon isotope compositions ( - C/ C) are expressed relative to that of the Pee Dee Belemnite (PDB) standard. 

Figure 3t. Isotope age functions of organic carbon (Corg) over 3.8 billion years of recorded Earth s history as compared with the isotopic composition of their progenitor substances in the present environment (marine bicarbonate and biogenic matter of various parentage cf. Right panel). Isotopic compositions are given in values, indicating either a relative increase (+j or decrease (—) in the C7 C ratio of the respective substances (in per mil difference) as compared to that of the Pee Dee Belemnite (PDB) standard with =...

CSIA yields data of the isotopic composition of a single compound relative to an international standard that is usually expressed as delta notation (S) values in parts per thousand (%o) according to Eq. 1. The most common ones, the carbon and hydrogen isotopic compositions (R), are reported as and relative to Vienna Pee Dee Belemnite standard (V-PDB) and Vienna Standard Mean Ocean Water (V-SMOW), respectively [20] ... 

The stable carbon isotope ratios of dissolved inorganic carbon (DIC) and benthic foraminiferal calcite generally are determined with isotope ratio gas mass spectrometers calibrated via NBS 19 international standard to the VPDB (Vienna Pee Dee Belemnite) scale. All values are given in 8-notation versus VPDB with an overall precision of measurements including sample preparation usually better than +0.06 and +0.1%o for calcite and DIC carbon isotopes, respectively. Except one single-specimen based dataset (Hill et al. 2004), all stable isotope data from papers referred to in this overview are from species-specific multi-specimens analyses. The number of specimens used for a single analysis depended on size and weight of species but usually varied between 2 and 25. 

Stable isotopic compositions are reported relative to Vienna Pee Dee Belemnite (VPDB) using the NBS-19 standard and the following equation ... 

Little precise information is available regarding the carbon isotopic composition in major planetary reservoirs in the solar system (with the exception of Mars, discussed below), or in the Sun. Determination of isotopic abundances from photospheric observations is difficult a high resolution study of CO molecular lines yields CrC = 84 5 (Harris et al. 1987). Lacking a precise and meaningful reference value for average solar system, by tradition carbon isotope ratios in extraterrestrial materials are defined relative to the Pee Dee Belemnite with = 0.011237 (Craig 1957). 

Figure 12. Sedimentary and geochemical records from oceans, showing dramatic transient shifts in most records in an interval from just before 8 Ma to 4 Ma (shaded), from Filippelli (1997b). Symbols in all records represent averages of 1 Myr intervals, except for normalized sediment flux curve, which represents 0.5 Myr averages. After interval averaging, all records were adjusted to time scale of Cande and Kent (1992) for consistency, (a) Normalized sediment flux in northern Indian Ocean (Rea 1992). (b) Ge/Si ratio in opaline silica from diatoms (Shemesh et al. 1989). (c) of bulk marine carbonates (Shackleton 1987). Although details of different carbon isotope records differ, general trends revealed in this low-resolution record are robust. PDB is Pee Dee belemnite. (d) Phosphorus accumulation rates in equatorial Pacific (Filippelli and Delaney 1994). Peak in accumulation rates is also observed in other parts of Pacific (Moody et al. 1988) and western Atlantic (Delaney and Anderson 1997). These peaks are linked with increased phosphorus input rates from continental weathering (e.g., Filippelli and Delaney 1994). (e) Sr/ Sr record from marine carbonates (Hodell et al. 1990, 1991). (f) of benthic foraminifera (Miller et al 1987).

Pee Dee Belemnite), which describes the composition of calcite carbon in Belemnites of the Pee Dee Formation (USA, South Carolina). 

PDB Pee Dee Belemnite, a belemnite fossil from Pee Dee Formation, South Carolina, USA. 

---