CO2 supersaturation in lakes in Florida

Ragnarok

Junior Poster
Nov 15, 2015
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You can download the PDF from the web archive: https://web.archive.org/web/20140829...2_FL_lakes.pdf


In case it's not available any more in the archive, try to search its DOI: 10.1007/s10750-009-9723-y


370 µatm = 0.4 mg/l (equilibrium)


1,030 µatm = 1.1 mg/l (median)



3,550 µatm = 3.8 mg/l (mean)



81,000 µatm = 87.5 mg/l (max)



So the PDF states the median is 1.1 ppm CO2 which is not that high. The supersaturated means anything above 0.4 ppm CO2 (= equilibrium with air concentration).
 
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brrrpr

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Jun 1, 2016
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Thank you very much, I still have to read the article but this is a data that I've been looking for ever since, I found a lot of articles about Oxygen content inside the water but nothing about CO2 related to plant growth. I did myself some checking in Italian rivers, lakes and even sea; of course my testing was "ridiculous" if we are talking in terms of scientific precision but that was not my goal. I just needed to have a rough idea of what the natural CO2 content was in natural basins of water and compare the natural environment with our aquariums, where we want our plants to grow and be in best conditions. We consider the right CO2 amount in our tanks to be around 20 mg/l up to 30 mg/l but this is something that almost never occur in nature. The highest amount recorded by me was on the sea shore where I found an exceptionally high CO2 content of 9 mg/l which was a surprise for me and it was higher than in comparison the freshwater rivers and lakes where I found values around 5 to 8 mg/l. This year I will do it again.


But the real big question is: if in captivity most demanding plants require at least 20 mg/l of CO2 to grow where do they get it from in natural environments ?
 

Tom Barr

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Ground water, bacteria, sediment, low plant biomass to water volume. Florida has many fresh water springs. They are loaded, as most all limestone springs, with CO2 rich water.
 

Martien

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Feb 14, 2013
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The mountain stream bordering our property has dKH 1,5 and pH 5,5. That is a lot of CO2. EC is 53 uS. Tested it today. It has Ranunculus penicillatus in it. The water is clear, but has a silvery shine to it. As if it is misty. There is no human pollution whatsoever. The rock bed is granite. Do you have any idea where that shine comes from? CO2?
 

Tom Barr

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CO2 is common in ground water, silt and other minerals can enter the water.
 

brrrpr

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Jun 1, 2016
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Tom Barr said:
Ground water, bacteria, sediment, low plant biomass to water volume. Florida has many fresh water springs. They are loaded, as most all limestone springs, with CO2 rich water.

So the CO2 content in these specific environments can reach up to the "aquarium levels", like 20 ppm or more ?


But in many other natural environments I have monitored the CO2 level is much lower, between 6 to 8 ppm and the local plants are still thiving and this makes me a bit confused, may be the plants I have seen (different types of Potamogeton, Myrophillum, Callitrice stagnalis, Ranunculus etc.) they can grow without much CO2 amount where they have KH as a source of carbon. When they reach the top they have access to the atmosphere but it is when they are still submerged that the CO2 is low.
 
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1077

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Aug 19, 2010
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I think many of the aquatic plant's are bog plant's that grow with root's below water, leaves above water, or anchored to edge of stream's where their root's are below water but leaves are above water where the plant's have much more access to CO2 from atmosphere as well as what may be available in water .
 

Tom Barr

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They can reach much higher than that, but 15-30 ppm are pretty common from limestone and other springs.


Many of the other species tend to amphibious also, the weeds you mention are quite good at a wide range of conditions, but adding more CO2 helps a good deal.


Plants still grow at lower CO2, they just grow much slower.
 

brrrpr

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Jun 1, 2016
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Today I will collect data from a small pond where plants are trhiving and no CO2 is injected. An enormous biomass (leaves and detritus) are present, about 80% of the volume occupied by plants.


One of my aquariums where I collected CO2 samples gave me an incredible 22 ppm (without injecton) but this high value was questioned by my friends. I don't know what to say, I was surprised myself but the aquarium had no filter, a very thick 4 to 6 inches substrate with a lot of dead leaves.and a bit of turf mixted in the middle.


Is it possible ?


How reliable could the Tetra CO2 test be ? (and the CO2 tests in general).


Is there any other source of carbon produced by the biotope (apart from the dKH and carbonates) that can be exploited by plants ? Like rottening biomass or other biochemical reactions ?
 
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