<p>"The decrease in &delta;<sup>13</sup>C as water flows from the Atlantic to the North Pacific is due mainly to the addition of organically produced material and its subsequent oxidation as it falls through the water column. Marine organic carbon has a &delta;<sup>13</sup>C of near -25<sup>0</sup>/<sub>00</sub>, hence the addition of this material decreases the &delta;<sup>13</sup>C of the &Sigma;CO<sub>2</sub>." (from conclusion)</p>

<p>P. M. Kroopnick, <em>Deep-Sea Research Part a-Oceanographic Research Papers</em>, 1985, <strong>32</strong>, 57-84.
<a href="https://www.sciencedirect.com/science/article/pii/0198014985900172" rel="nofollow noreferrer">https://www.sciencedirect.com/science/article/pii/0198014985900172</a></p>

CC BY-SA 4.0
2020-05-06T09:23:03.260Z
2020-05-06T09:23:03.260Z
William Harvey
<p>Due to thermohaline circulation, the Pacific water is more 'aged' so there is a higher amount of total dissolved inorganic carbon (e.g. CO<sub>2</sub>) in the deep Pacific when compared to the Atlantic. However, I don't know how this affects the relative <sup>13</sup>C/<sup>12</sup>C enrichment of the Pacific.
Factors I've thought about:</p>

<ol>
<li>Oxic respiration of buried organic matter is the source of CO<sub>2</sub> in the deep ocean.</li>
<li>Deep Pacific water has accumulated more respired CO<sub>2</sub> since the Pacific is at the end of the deep circulation.</li>
<li>Algae and microbes fractionate against <sup>13</sup>C in favour of <sup>12</sup>C.</li>
</ol>

<geochemistry><co2><carbon-cycle><thermohaline-circulation><pacific>
Is CO2 in the Pacific Ocean depleted or enriched in Carbon-13 compared to the Atlantic, and why?
William Harvey
# Is CO2 in the Pacific Ocean depleted or enriched in Carbon-13 compared to the Atlantic, and why?

(Asked by: username_0 on 2020-05-04)

Due to thermohaline circulation, the Pacific water is more 'aged' so there is a higher amount of total dissolved inorganic carbon (e.g. CO2) in the deep Pacific when compared to the Atlantic. However, I don't know how this affects the relative 13C/12C enrichment of the Pacific.
Factors I've thought about:

1. Oxic respiration of buried organic matter is the source of CO2 in the deep ocean.
2. Deep Pacific water has accumulated more respired CO2 since the Pacific is at the end of the deep circulation.
3. Algae and microbes fractionate against 13C in favour of 12C.

**Tags:** geochemistry, co2, carbon-cycle, thermohaline-circulation, pacific


---

## 1 answers

### Answer by username_0 on 2020-05-06. Score: 1

"The decrease in δ13C as water flows from the Atlantic to the North Pacific is due mainly to the addition of organically produced material and its subsequent oxidation as it falls through the water column. Marine organic carbon has a δ13C of near -250/00, hence the addition of this material decreases the δ13C of the ΣCO2." (from conclusion)

P. M. Kroopnick, *Deep-Sea Research Part a-Oceanographic Research Papers*, 1985, **32**, 57-84.
<https://www.sciencedirect.com/science/article/pii/0198014985900172>


---

