|MadSci Network: General Biology|
Hi, Noticing that you are in HK, I think morning is still the better time to go uphill. Because human activities and pollution, which consume oxygen, are much heavier than that in morning, the air is far from fresh. The answer to your question would be yes if we were in an optimal condition with plants as the only variable. However, in natural conditions many limitations will generally limit photosynthesis. For example, pollution will inhibit photosynthesis and plant growth; high temperature will increase respiration of plant, which also consumes oxygen. Further, a large part (probably the majority) of photosynthetic productivity occurs in open oceans, mostly by oxygenic prokaryotes. So in a big city, the amount of oxygen produced by its trees is far less than the amount this city consumes. Therefore, noon is not a good time to go out and get fresh air. Reference: Some websites are good for general public to understand photosynthesis: http://photoscience.la.asu.edu/photosyn/education/photointro.html http://www-new.life.uiuc.edu/govindjee/ptime/
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