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The δ 13 C anomaly in the northeastern Atlantic
Author(s) -
Keir Robin,
Rehder Gregor,
Suess Erwin,
Erlenkeuser Helmut
Publication year - 1998
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/98gb02054
Subject(s) - biosphere , dissolved organic carbon , isotopes of carbon , carbon fibers , phosphate , total inorganic carbon , environmental science , total organic carbon , nutrient , environmental chemistry , geology , oceanography , mineralogy , chemistry , carbon dioxide , ecology , biology , materials science , organic chemistry , composite number , composite material
The δ 13 C of dissolved inorganic carbon was measured on samples collected at 49°N in the northeast Atlantic in January 1994. Deeper than 2000 m, δ 13 C exhibits the same negative correlation versus dissolved phosphate that is observed elsewhere in the deep Atlantic. Upward from 2000 m to about 600 m, δ 13 C shifts to values more negative than expected from the correlation with nutrients at depth, which is likely due to penetration of anthropogenic CO 2 . From these data, the profile of the anthropogenic δ 13 C decrease is calculated by using either dissolved phosphate or apparent oxygen utilization as a proxy for the preanthropogenic δ 13 C distribution. The shape of the anthropogenic anomaly profile derived from phosphate is similar to that of the increase in dissolved inorganic carbon derived by others in the same area. The reconstruction from oxygen utilization results in a lower estimate of the anthropogenic δ 13 C decrease in the upper water column, and the vertical anomaly profile is less similar to that of the dissolved inorganic carbon increase. A 13 C budget for the atmosphere, ocean, and terrestrial biosphere indicates that within the range of probable ocean CO 2 uptake the ratio of δ 13 C to inorganic carbon change should be mostly influenced by the 13 C inventory change of the biosphere. However, the uncertainty in the ratio we derive prevents a strong contraint on the size of the exchangeable biosphere.