We take the various components of our biosphere very much for granted. We are creatures of air and water and carbon and damn little else. Our cycle of life uses sunlight to split carbon dioxide into biologically usable carbon and oxygen. Put that way it all seems so simple that we delude ourselves into thinking we understand it all.
Each core ingredient has its own natural sink, the most obvious been the ocean. If we dug up every poison on earth and threw it into the ocean, I suspect that the ocean could handle it far quicker than we could ever imagine. My only reservation comes when some genius creates a new molecule that is both toxic and biologically inert. I prefer not to have to wait for geological processes to cure the problem.
The other big sink is the carbon sink and no, that is not the biosphere. I mean that stack of rock over eighty miles thick that we call the crust. It is loaded with carbon throughout and at its deepest it is in elemental form. In the sediments it is held as both coal and hydrocarbons were conditions are right. Far more are held in the form of carbonates in which silicas and the like have combined with good old CO2 to form materials able to withstand the conditions of the deep crust.
The carbon in the biosphere pales in comparison to this carbon sink. This should also give you a glimpse of just how removed the crustal rock is from the primordial rock environment like Mars or Venus. Water and carbon is an incredibly powerful mortar and pestle when animated by life.
The last great sink is of course the atmosphere. It is primarily inert nitrogen and oxygen which is critical to the living biosphere that produces the oxygen. The drivers of these components are still poorly understood as far as I have been able to determine, or at least poorly explained.
In practice, the biomass pumps out surplus oxygen into the atmosphere successfully supporting a plus seventeen percent level. I suspect this figure reflects areas of high human population in which some level of oxygen depletion. A more likely figure of 21% should prevail outside and upwind of human activity. Of course, burning 85 million barrels of oil every day must cause depletion somewhere.
The measure of our lack of knowledge hits the wall when we discuss the oxygen content of biologically active water. The literature maintains that all oxygen is supplied by dissolved oxygen from the atmosphere, except that the maximum oxygen that can be carried in water is seven parts per million. It stretches credulity to think that this can do the job. This is one of those conundrums that were postponed for future resolution a long time ago and that future never came.
In the final analysis the literature and text books merely became quiet on this subject. How many other problems have been so treated? Remember, had the problem been explained by simple analysis, you would have been taught it in high school.
I have come to the conclusion that biological oxygen is instead carried by the H3O3 ring molecule which can reach a stable one to two percent concentration level. This flattish molecule naturally forms needle crystals and is stable over all relevant temperature ranges. The molecular weight coincides with the unexplained background noise level of a spectroscope and has thus eluded direct discovery. The natural angles of the ring are also within the range of error for water.
I have had access to samples of this biologically produced solution and have used it to restore deficient blood oxygen levels and to sharply reduce burn damage. A glass of it allowed me to increase my breath holding capacity by a good fifty percent, as well as with many others. Of course the folks who produced the sample are clueless as to its likely genesis.
Thus if I am correct, biological oxygen is produced in situ by specialized bacteria as a waste product. Some of this will also escape into the atmosphere. I do not know if such bacteria need to use chlorophyll, but I rather doubt it. After all we know that chlorophyll was a late arrival to the primordial sea. Oxygen production and transport was necessary for life to utilize the available feed stocks. It is just that little of it was needed in the atmosphere.
It may even be possible to breathe this stuff if concentrated.
In any event, it is a good bet that the real oxygen sink is in the water rather than the atmosphere and that they are in some form of equilibrium with each other.
These simple sinks set the parameters for our Biosphere and our worst excesses are likely to never do more than inconvenience it and ourselves more so.