Nitrogen (N) and Phosphorus (P) are admittedly two crucial elements for growth – of crops and even our bodies. We learned that by supplementing these elements through “artificial fertilizers“, we enhance crops and can sustain our population and its well being. As we withdraw these elements from natural resources, and use them in the environment, we upset the natural balances around us causing nuisance or even accute toxicity. Just remember toxic potable water in Toledo, Ohio, red tide in Florida or eutrophic overgrowth of thousands of fresh-water lakes and streams and poisoning of what remains of Florida Everglades.
|Highly polluting algal blooms - sometimes toxic|
Phosphorus, however, is a different story -
“It's the phoshorus, stupid !“
- (paraphrasing former President Clinton).
It is an element that we “unearth“ and it lingers in the environment around us where we release it. While some of it supports production of our crops, most of it washes into “receiving water bodies“ - causing havoc. We do not have any mechanism whatsoever to put that genie back into the bottle. Wetlands, say some – wetlands remove phosphorus ! However, that just does not quite add up in simple mass balancing that teaches us –
what goes IN, that goes OUT or it ACCUMULATES
(this checks out even for your wallet $$).
So now, wait a minute – where does that phosphorus go when channelled into a wetland ? It cannot evaporate into thin air. It supports growth of wetland plants that grow and die in cycles. As part of this, the phosphorus becomes “mineralized“ – deposited in the bottom soil. Good, gone ! Not so fast – what happens to that bottom soil ?
It settles and – remains there with all the phosphorus that was removed from circulation - for the time being. P-rich bottom muds -
That is also close to the story of phosphorus-rich bottom muds in Lake Okeechobee and everywhere else where phosphorus-enrichment takes place, creating "legacy phosphorus“ mud and soil depositions – a looming threat, a time bomb and a major problem ! Because all that phosphorus can and does keep uncontrollably leaching out again –
By the way – sending water from LO south, as it is nowadays called for - there is so much phosphorus present AND deposited in LO that it can convert a third of Florida into a “biological desert“ overgrown with life-choking cattails instead of the Everglades native sawgrass. That LO water needs to be proportioned and cleaned first. It is a certainty that the indian tribes living downstream from LO just would not allow its pollution pouring south.
Phosphorus is a solid element that remains just that – in its solid or dissolved molecular forms.
Unlike nitrogen that can exist as free gas – and pooof, off it goes then, ‘disappearing‘ back into the atmosphere. Phosphorus is phosphorus is phosphorus – sometimes dissolved, sometimes in a combined solid, it does not ‘disappear‘ as gas. While we desperately need it, there are only rather limited quantities of it to mine on the earth (mostly in Morocco, some in China, some in Florida). We mine it and throw it around, literally.
|Phosphate mining in Morocco - our P is a finite resource !|
And so what ?
Some rather nagging practical questions emerge – what happens to the phosphorus “removed“ in the STAs (huge-scale constructed wetlands) that Florida is frantically trying to build ? For how long can we keep accumulating phosphorus in their bottom muds ? Is that becoming another “legacy phosphorus“ for next generations to worry about then ?
It would be wise to introduce some common sense in phosphorus husbandry and control. Using slow-release fertilizers and strictly controling their application could be a good start. Recovery of phosphorus from our waters – and from our muds - should be attempted. We have to address these issues.
Of course, it is quite difficult because phosphorus control and recovery goes “uphill“ against the 2nd law of thermodynamics and entropy – am I overwhelming you ? Of course -
Let’s just say – it is easy to go from concentrated to dilute forms of substances - but it is difficult (and energy requiring) to go back from dilute to concentrated. We would want to not just remove phosphorus when it contaminates our surface waters but to recover it for effective re-use.
We need a techno-scientific breakthrough there.
That is what the $10-million Prize recently announced by the Everglades Foundation is all about. Good luck !
|Agriculture fields pollute - the problem to be corrected by vast artificial |
wetlands (STAs) that are supposed to clean up. Will they ? For how long ?