Re: [Aroid-l] Plants cause oxygen deprivation at night???????

From: "mossytrail" <mossytrail at hctc.com> on 2010.02.17 at 02:29:12(20610) Sleeping with head under the covers scares you? What are your bedcovers made of? Plastic? > > I can?t add to the ideas Steve Marak presented, but I can > try some numbers. I hope the readers of Aroid-L will work > through my numbers here. It would be bad enough for me to > look like an idiot because I overlooked something that > changes the results by a factor of a hundred or so, but it > would be worse for the wrong results to stand without > correction. +More > > > > I asked a friend who did his doctoral work on plant > respiration and got the approximation that the emission of > CO2 in the dark is unlikely to exceed 4 micro moles per > square meter of leaf surface per second. This is the same > as the O2 taken up. Say our plants have a leaf area of one > meter. Let?s say for the sake of argument that both upper > and lower leaf surfaces emit at that rate, so our plants > use up 8 micro moles PER SECOND (please excuse the upper > case, but when we think of a whole night the seconds > really add up). > > > > In an 8-hour night, we have the 8 micro moles/s x 3600 s/h > x 8 h = 230400 micro moles of oxygen the plants take up. > That is only millionths of moles, so it amounts to 0.23 > mole. That got the number back down in a hurry. > > > > How much oxygen was in the room to start with? > > A room 4 m x 4 m x 2.4 m has 38.4 cubic meters of air. > That is 38400 liters. > > At room temperature, a mole of gas is about 25 liters, so > the room has 1536 moles of air. > > If we say the air in the room is 20 % oxygen, we have 307 > moles of oxygen to start with. > > > > How much of the total oxygen in the room did the plant > use? It is 0.23/307 = 0.075 %. > > > > What about our oxygen-starved sleeper? > > A person breathes out about 900 g CO2 per day or about 300 > g in an 8-hour night. > > CO2 has a mole weight of 44. > > 300/44 = 6.8 moles CO2 emitted = moles O2 taken up by a > person in the night. > > > > The 6.8 moles of oxygen used by the sleeping person > amounts to only about 6.8/307 = 2.2 % of that available. > > > > How do the plant and the sleeper compare? The plant uses > 0.23/6.8 = 3.4 % as much. > > > > With all the guessing (?approximation? in science-speak), > none of the numbers has any meaning unless it?s rounded > off to only one digit. You can insist that a sleeping > person uses less oxygen than an active one, the room is > smaller and the plant larger, but that doesn?t change > anything. A good-sized plant surface won?t reduce the > oxygen content of the room by much more than a tenth of a > percent, and that is only about three percent of what the > inhabitant uses up. > > > > If the sleeper is oxygen-starved, he or she probably isn?t > breathing right. It can?t be blamed on the plant. I?ve > known people who slept with their heads under the covers. > That does scare me. > > Walter Turner > _______________________________________________ Aroid-L mailing list Aroid-L@www.gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

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