# Tag Info

1.How much carbon is there on Earth? Taken as whole, the Earth is estimated to be 730 parts per million carbon by mass. So $4.4 \times 10^{21} kg$ http://quake.mit.edu/hilstgroup/CoreMantle/EarthCompo.pdf How much carbon is there in the atmosphere (in the form of CO2 and CO)? $3.1 \times 10^{15} kg$ CO2 and insignificant CO, so $8 \times 10^{... 8 The phosphorous sinks are the ocean and ocean sediments. The ocean holds$3 \times 10^{15}$moles of phosphorous. The annual amount of phosphorous input into the ocean, as well as the amount of burial of phosphorous as sediment is on the order of$10^{10}$moles. The sediment is of three categories: Phosphorous associated with calcium carbonate ... 8 To complement @MarkRovetta answer, McLoughlin & Grosch reported this year during EGU findings of carbonaceous fragments that they think are biogenic in the 3.4 Ga Buck Reef Chert. Chemical tests are still ongoing however. Schopf (2006) in his review of archean life reported a dozen of fossils in the 3 to 3.5Ga range. They are all "putative" fossil, ... 8 Fossils are our strongest, and to most people most accessible, evidence of the great age of life on earth. The fossils in the Burgess Shale are clearly the imprints of critters, but are a mere 505 million years old. The oldest cyanobacteria-like fossils known are nearly 3.5 billion years old, among the oldest fossils currently known. There is Evidence for ... 8 The oxygen in the atmosphere was produced by cyanobacteria during the Great Oyxgenation Event, around 2.3 billion years ago. Cyanobacteria produced & still, produces, to a lesser extent, oxygen by photosynthesis. Plants did not exist during the Great Oxygenation Event, but these day plants replenish atmospheric oxygen by removing carbon dioxide by ... 8 This is only a partial answer as it doesn't explain why the excess of O2 stayed but one thing you have to appreciate is the fact that aerobic respiration appeared almost half a billion years after photosynthesis, so we can't really say that photosynthesis and respiration have always balanced each other. Cyanobacteria (and with them photosynthesis) are ... 8 I'm not sure I can give a good technical answer. I don't think the amount of oxygen in the Earth's atmosphere is due to equilibrium but more of a consequence of the formation of the solar system, Earth chemistry and biology. If you look at the formation, for inner planets, much of the gas and ices were blown off due to their inner orbits and the planets ... 8 You are correct in thinking that oxygen comes from photosynthesis. In fact it is so much associated with photosynthesis, as opposed to any inorganic process, that the presence of oxygen in the atmospheric spectrum of other planets (solar or exoplanets) is reckoned to be one of the best indicators of life beyond Earth - not that such oxygen has been ... 8 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 sun" as an approximation. However, some approximations are pretty good for all practical purposes. Nevertheless, this approximation (even if right), have some ... 7 Mg C is a tonne of Carbon. An Mg - a megagramme - is a tonne. It's a silly way of writing a tonne for a general readership, but it's the strict SI equivalent of a tonne. So an "Mg C" is a tonne of Carbon - the standard unit when it comes to talking about pricing Carbon. Normally you wouldn't see anyone writing about a million Mg of anything; (in this case, ... 7 The difference is that a carbon sink accumulates carbon, whereas a carbon reservoir has accumulated carbon. That is to say: A carbon sink is an ongoing process which is increasing the amount of carbon stored in it. Whereas although a carbon reservoir might exchange individual carbon-based molecules with other parts of the carbon cycle, as much will go out ... 7 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 minerals and such bacteria form the base of a food chain. Also, the heat from the hot water can provide energy to life forms. 6 Getting figures on the amount of limestone available is difficult. Apparently "limestone makes up at least 10% of the total volume of all sedimentary rocks". One way to answer your question is by inference. Cement is manufactured from limestone. Current global production of cement is in excess of 3.27 Gt/a and by 2030 it is forecast to be approximately 4.... 6 Reading your comments I see that you're asking: so could we find for example 1km high limestone layers on earth ? The answer is definitely yes. Here's an example of a stratrigraphic geological section from Israel: source: Chronostratigraphic table and subsidence curves of southern Israel, Gvirtzman 2004, Israel Journal of Earth Sciences, 53 You can see ... 6 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 hydrotermal vents if the planet is geologically active. The latter is likely to be the case, because assuming you meant water oceans, to have that much water ... 5 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 which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or other molecules available to living organisms. Nitrogen fixation has the chemical ... 5 The rates at which plants consume CO$_2$and animals consume O$_2$is minuscule compared to the vast amounts of CO$_2$and O$_2$in the atmosphere. The amount of change overnight is not even measurable, unless the plants are in an enclosed structure. Interestingly, there is a variation in CO$_2$concentraion over the course of a year as the Northern ... 5 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 whole site carbon storage and above ground biomass carbon storage. There is also ongoing research taking place which (as you might imagine) takes a very long time ... 4 A carbon reservoir is measured by the amount of carbon it contains, for example kilograms of carbon [kg C]. A carbon source or sink is measured by the amount that comes out or into the reservoir from the rest of the system per unit of time, for example kilograms per day [kg C/day]. A coal or oil deposit can be either a reservoir or source, as carbon flows ... 4 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 there are is no known direct fossil evidence so instead we have to rely on geochemical evidence. As the OP mentioned, the oldest known sedimentary rock, the ... 4 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 exposes more rock that can be oxidized) and cooler oceans (which can then absorb more oxygen). So, while it is a slow process on geologic timescales, the amount ... 4 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 later I ran into a bonafide clay scientist who said "Of course!" when I asked her about clay's role in establishing early life. Anyway... I suspect that ... 4 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 were many many times higher (~20X) than today. Hydrogen was not released it was combined with carbon and oxygen to make sugars 4 850 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 current levels of 20%. 14% was attained about 500 million years ago, but there have been significant low oxygen events since, notably at the start of the ... 3 When discussing about the carbon cycle in scientific papers, the gram is usually the reference unit used. Depending on what the particular topic is, and especially its scale, an appropriate prefix will be appended to the gram unit. For instance, when the target is hemispheric or global, petagrams (Pg) is often used to discuss carbon exchanges between large ... 3 Yes, there is much more than enough limestone, by several orders of magnitude, to neutralize the acidity that we are creating - so much so that I am not even going to bother with the back of an envelope calculation. Given enough time (many millennia and possibly several million years) this will happen naturally. However,the process of re-equilibration with ... 3 There are multiple companies that provide COD sensors... Real Tech Inc, LAR, Detectronic, Endress-Hauser, and YSI... but they all use spectrophotometry methods. 3 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 sensor listed uses a BOD equivalent monitoring technique. The governing environmental regulatory agencies for a specific waste water facility should have ... 3 You have to use mass weighted averaging to calculate the final concentrations of elements. The equation for your situation would be:$\sf\bar{q}\ =\ \dfrac{m_1.q_1\ +\ m_2.q_2}{m_1\ +\ m_2}\ =\ \dfrac{\rho_1.v_1.q_1\ +\ \rho_2.v_2.q_2}{\rho_1.v_1\ +\ \rho_2.v_2}$where:$\small\sf m$is the mass flow rate$\small\sf v$is the volume flow rate$\small\rho\$ ...