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8 votes
Accepted

Is it true that "All life on earth gets its energy from the sun"? How much biomass is not derived from photosynthesis?

As you say, the existence of organism that live out of chemical compounds expelled by hydrothermal vents (Chemoautotrophs), immediately render the sentence "All life on earth gets its energy from the ...
Camilo Rada's user avatar
  • 17.7k
7 votes

How would a world entirely covered in oceans get the nutrients to support life?

If the planet is geologically/volcanically active hydrothermal vents are a way by which nutrients, in the way of minerals and chemicals, can enter the ocean. Certain types of bacteria can consume the ...
Fred's user avatar
  • 24.7k
6 votes

How would a world entirely covered in oceans get the nutrients to support life?

On an ocean planet, nutrients can come either from space or from the bottom of the ocean, where they can leak from the crust trough different processes, perhaps with the help of submarine volcanoes or ...
Camilo Rada's user avatar
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5 votes

Do trees capture more CO2 during a fast growth stage?

Right, there are a lot of misconceptions about this. They are mostly to do with the difference between the magnitude of carbon storage and the rate of carbon uptake, and also the difference between ...
Will's user avatar
  • 494
5 votes

Before the Great Oxygenation Event, where was the oxygen?

the great oxygenation event was caused by the evolution of photosynthesis, photosynthesis turns CO2 and water in to sugar and oxygen. so the oxygen came from CO2 and water. keep in mind CO2 levels ...
John's user avatar
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5 votes

Nitrogen cycle semantics; nitrification/nitrogen fixation

I went to do a bit of research on this, and think that you can get a satisfactory answer just from the relevant wikipedia articles. Here are some select quotes: Nitrogen fixation is a process by ...
kingledion's user avatar
  • 3,376
5 votes

How is the equilibrium of 21% oxygen in Earth's atmosphere established?

Atmospheric oxygen is not in an equilibrium of 21%, it just changes very slowly. For instance, oxygen has decreased by 0.7% over the past 800 thousand years, likely due to increased erosion (which ...
f.thorpe's user avatar
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5 votes

Why don't most organisms use magnesium in their shells and bones if it is lighter and more common than calcium?

First off, magnesium is not more common than calcium where it counts for Earth organisms, namely the crust. By mass calcium is more common in the crust, by atoms they are about equal (the enrichment ...
Oscar Lanzi's user avatar
  • 3,926
4 votes

What is the age of the earliest traces of life on Earth?

The oldest (fairly) definitive fossils date from about 3.48 billion years ago (Ga) and consist of sedimentary structures associated with microbial mats living in coastal environments.[1] Beyond this ...
bon's user avatar
  • 2,211
4 votes

Before the Great Oxygenation Event, where was the oxygen?

I'd like to add to the other answers. Yes, it is correct that photosynthesis by cyanobacteria caused the rise of atmospheric oxygen. Some important points to talk about: Estimated fossil fuels are ...
Gimelist's user avatar
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4 votes
Accepted

Abiogenesis: Formation of Lipids from Montmorillonite

Good question! One that's stuck with me since reading about clay's purported role in providing scaffolding to early organic molecules in a Scientific American article from the late '80s. Many years ...
Knob Scratcher's user avatar
4 votes
Accepted

How quickly can coral fossilize?

First thing is that the sea-level wasn't necessarily that high when the reef was growing, Hondurus is on the edge of the Caymen Trough Fault Zone and experiences quite high rates of uplift, (...
Ash's user avatar
  • 4,390
4 votes

How far into the past would you have to go before you couldn't breathe the atmosphere?

850 million years ago and earlier oxygen levels were below 6%, which is the minimum for human survival. But at oxygen levels below 14% we start to be significantly impaired, and we have evolved with ...
Andy M's user avatar
  • 2,091
4 votes

How do I convert an element measurement to oxides?

If you are talking about Table 2 of Chapter 8 in Principles of Igneous and Metamorphic Petrology (Winter, 2013), p. 146 in the second edition, then you are misreading the column headers. 59.3 is in '...
Jean-Marie Prival's user avatar
3 votes

How far into the past would you have to go before you couldn't breathe the atmosphere?

Roughly 3,000,000,000 years ago Earth was a water world. This means terrestrial flora and fauna was 0%. Not much fun breathing in the atmosphere with limited photosynthesis from plants. And a nitrogen ...
Science nerd's user avatar
3 votes

How much net carbon can coral sequester?

Corals usually grow 1cm every year, some as slow as 2mm, some faster. Coral sand density is about 1.5g /cm2, it's not the best estimate of coral weight. So, a coral organism of 10cm^2 produces 150 ...
bandybabboon's user avatar
  • 1,349
3 votes
Accepted

Where does molecular hydrogen in the atmosphere come from?

I've found two sources for molecular hydrogen. The photolysis of formaldehyde (See chemical formula 10 and see Novelli et al. 1999) Anthropogenic sources. While it isn't a source I think I should ...
BarocliniCplusplus's user avatar
3 votes
Accepted

Will photosynthesis based carbon sequestration always be more efficient than other chemical means - in terms of rate?

Rate.. no. Brute Force We can treat this as an industrial chemistry question. The brute-force method for carbon sequesteration is simply: Extract CO2 from the air (using the acid/base chemistry, ...
Andrew Jon Dodds's user avatar
3 votes

Can you measure BOD/COD real time using any sensor?

There are multiple companies that provide COD sensors... Real Tech Inc, LAR, Detectronic, Endress-Hauser, and YSI... but they all use spectrophotometry methods.
mohammad farhady's user avatar
3 votes
Accepted

Can you measure BOD/COD real time using any sensor?

Realtech.com has a runtime monitoring senser solution for BOD/COD Sensor. My understanding is that COD is straight-ward to measure in real-time but BOD monitoring cannot be done in real-time. The ...
Earth Science Expatriate's user avatar
2 votes

Why does Earth have abundant oxygen in the atmosphere?

My answer goes a little beyond the evidence -- there isn't much evidence. The question There's a lot of free oxygen now. This oxygen did not suddenly come from underground or from space. So it used ...
J Thomas's user avatar
  • 281
2 votes

What are the natural causes for methane formation?

The 'natural causes' of global methane emissions are, as you indicate, mostly of biological origin. To some extent it depends upon what you regard as 'natural'. There are many and differing estimates ...
Gordon Stanger's user avatar
2 votes
Accepted

calculation monocationic elements

Oxygen is always divalent negative. An oxide has to be charge balanced, meaning the total has to be zero. Therefore, some like CaO means you have Ca2+O2-. Something like SiO2 is going to be Si4+2O2-....
Gimelist's user avatar
  • 23.1k
2 votes

Will photosynthesis based carbon sequestration always be more efficient than other chemical means - in terms of rate?

Photosynthesis is up to about 2% efficient while solar panels are above 20% efficient. So just based on the energy available per unit area of sunlit land or sea, chemical carbon sequestration holds ...
Chris Jenks's user avatar
2 votes

Where does molecular hydrogen in the atmosphere come from?

Besides man-made sources, hydrogen can be produced naturally through a process called serpentization. Mafic and ultramafic rocks, which are rich in magnesium and iron silicates, react with water to ...
Oscar Lanzi's user avatar
  • 3,926
2 votes

How to convert Carbon stored in surface sediments (kg/m2) to percent?

To answer your question requires some assumptions. Firstly in what is meant by kg Carbon/m2? m2 is a measure of area, not volume. So you might quote carbon deposition in kg/m2/year - and that wouldn't ...
Andy M's user avatar
  • 2,091
1 vote

Atmospheric $\ce{CO2}$ fell at a Pleistocene interglacial-glacial transition. Ocean absorption vs biosphere absorption

CO2 follows temp, not the other way around. When temperatures decline, biological activity decreases and available biologically derived carbon also declines. When temps increase and soil carbon ...
LazyReader's user avatar
1 vote

Is the ocean a carbon sink when considering only the biospheric component?

Yes, the marine biosphere is a carbon sink, and a very important one. It is known that the oceans produce more oxygen and biologically consume more carbon dioxide than all the tropical rainforests. ...
Michael Walsby's user avatar
1 vote

Before the Great Oxygenation Event, where was the oxygen?

Someone (I've lost track of whom. Tl;dr.) is seriously underestimating the amount of reduced carbon in sediments. Having examined (and logged, and submitted to oil companies and government, hundreds ...
Rockdoctor's user avatar
1 vote

Before the Great Oxygenation Event, where was the oxygen?

What I have learned from this is that things were very different before the Great Oxygenation Event; more than just the same elements rearranged. If all of the free oxygen came from water (and the ...
J Thomas's user avatar
  • 281

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