Ocean productivity before about 1.9 Gyr ago limited by phosphorus adsorption onto iron oxides

TY - JOUR

T1 - Ocean productivity before about 1.9 Gyr ago limited by phosphorus adsorption onto iron oxides

AU - Bjerrum, Christian J.

AU - Canfield, Donald E.

PY - 2002/5/9

Y1 - 2002/5/9

N2 - After the evolution of oxygen-producing cyanobacteria at some time before 2.7 billion years ago, oxygen production on Earth is thought to have depended on the availability of nutrients in the oceans, such as phosphorus (in the form of orthophosphate). In the modern oceans, a significant removal pathway for phosphorus occurs by way of its adsorption onto iron oxide deposits. Such deposits were thought to be more abundant in the past when, under low sulphate conditions, the formation of large amounts of iron oxides resulted in the deposition of banded iron formations. Under these circumstances, phosphorus removal by iron oxide adsorption could have been enhanced. Here we analyse the phosphorus and iron content of banded iron formations to show that ocean orthophosphate concentrations from 3.2 to 1.9 billion years ago (during the Archaean and early Proterozoic eras) were probably only ∼10-25% of present-day concentrations. We suggest therefore that low phosphorus availability should have significantly reduced rates of photosynthesis and carbon burial, thereby reducing the long-term oxygen production on the early Earth - as previously speculated4-and contributing to the low concentrations of atmospheric oxygen during the late Archaean and early Proterozoic.

AB - After the evolution of oxygen-producing cyanobacteria at some time before 2.7 billion years ago, oxygen production on Earth is thought to have depended on the availability of nutrients in the oceans, such as phosphorus (in the form of orthophosphate). In the modern oceans, a significant removal pathway for phosphorus occurs by way of its adsorption onto iron oxide deposits. Such deposits were thought to be more abundant in the past when, under low sulphate conditions, the formation of large amounts of iron oxides resulted in the deposition of banded iron formations. Under these circumstances, phosphorus removal by iron oxide adsorption could have been enhanced. Here we analyse the phosphorus and iron content of banded iron formations to show that ocean orthophosphate concentrations from 3.2 to 1.9 billion years ago (during the Archaean and early Proterozoic eras) were probably only ∼10-25% of present-day concentrations. We suggest therefore that low phosphorus availability should have significantly reduced rates of photosynthesis and carbon burial, thereby reducing the long-term oxygen production on the early Earth - as previously speculated4-and contributing to the low concentrations of atmospheric oxygen during the late Archaean and early Proterozoic.

UR - http://www.scopus.com/inward/record.url?scp=0037046523&partnerID=8YFLogxK

U2 - 10.1038/417159a

DO - 10.1038/417159a

M3 - Journal article

C2 - 12000956

AN - SCOPUS:0037046523

SN - 0028-0836

VL - 417

SP - 159

EP - 162

JO - Nature

JF - Nature

IS - 6885

ER -