Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anoxygenic photosynthesis and the delayed oxygenation of Earth's
  atmosphere   The emergence of oxygenic photosynthesis created a new niche with dramatic
potential to transform energy flow through Earth's biosphere. However, more
primitive forms of photosynthesis that fix CO2 into biomass using electrons
from reduced species like Fe(II) and H2 instead of water would have competed
with Earth's early oxygenic biosphere for essential nutrients. Here, we combine
experimental microbiology, genomic analyses, and Earth system modeling to
demonstrate that competition for light and nutrients in the surface ocean
between oxygenic phototrophs and Fe(II)-oxidizing, anoxygenic photosynthesizers
(photoferrotrophs) translates into diminished global photosynthetic O2 release
when the ocean interior is Fe(II)-rich. These results provide a simple
ecophysiological mechanism for inhibiting atmospheric oxygenation during
Earth's early history. We also find a novel positive feedback within the
coupled C-P-O-Fe cycles that can lead to runaway planetary oxygenation as
rising atmospheric pO2 sweeps the deep ocean of the ferrous iron substrate for
photoferrotrophy.

5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org