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Nice paper on NH4, O2, NO3/NO2 in the sediment

Discussion in 'Aquatic Microbiology' started by Tom Barr, Jan 8, 2007.

  1. Tom Barr

    Tom Barr Founder
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  2. BHornsey

    BHornsey Lifetime Charter Member
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    Hi Tom,
    Don't seem to be able to access the second page. It's showing an image of p529 and an abstract underneath.
    It won't let me peruse further as I don't have JSTOR access rights
     
  3. paludarium

    paludarium Guest

    Try this link:
    http://www.aslo.org/lo/toc/vol_42/issue_3/0529.pdf
     
  4. paludarium

    paludarium Guest

    Hi Tom,

    on page 532, as the results showed oxygen fluxes from the sediment into the water.... The net O2 release during illumination was highest from the bare sediment, and the net O2 uptake during darkness was highest in the Lobelia sediment. These words were astonishing to me, especially I cannot figure out why net O2 release during illumination was highest from the bare sediment?

    Regards,
    Erich
     
  5. Tom Barr

    Tom Barr Founder
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    The O2 is being used in the other sediment(bacteria, reducing sediments etc), in bare sand, the O2 simply gets higher. Nothing there to consume it.

    This is how a sediment goes sour in some tanks with too much organic material/poor root growth etc.

    Regards,
    Tom Barr
     
  6. paludarium

    paludarium Guest

    Well, the authors did not use bare sand, but the sediment that would contain both nitrifying and denitrifying bacteria.:confused:
     
  7. Tom Barr

    Tom Barr Founder
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    I thought you meant the bare sand without nutrients etc.

    The plant increased denitrification by 30% or more.
    So plants help NO3=> N2 gas, basically losing N. This is bad if you are trying to use NO3 as plant biomass/fertilizer( our tanks).


    It also shows that the sediment, rather than a filter, can act strongly under good plant growth to nitrify NH4 via O2, and then the less aerobic parts, denitrify. In sediments without roots, the process never really gets going with NH4=> NO2=> NO2=> NO3 since it's an O2 intensive trasformation. The roots are adding lots of O2(this was measured here) and enhance the bacteria, not just take up nutrients as NH4/NO3................

    So what happens when you up root too much sediment? It's a bit like upsetting you filter too much.

    If you purge your filter not too big of an issue in planted tanks, but if you purge too much sediment and the filter, you will have issues. Uprooting does other things like lower O2 overall oif you do too much.

    Hard to say how much is too much, so anytime you uproot, make sure to do a large water change afterwards, keep the % of the bottom to say no more than 1/3 at a time perhaps 3-4days.

    The link between roots, bacteria and plants and N seem pretty clear. Some suggest it's all about NH4 preferences etc. I highly doubt that. There are way too many things occurring in natural habitats and plants need many tools and forms of N and modify O2 levels to make it in wetland sediments.

    They showed here that roots enhance nitrification/denitification and also sequester N(NH4/NO3). They increase the rates of uptake, transformations(NH4=> N2 gas export out of water), enhanced by working with bacteria.

    Many of the wetland of the soils in CA are fairly N limited for this reason, so we have more P than N as far a critical ratio for plant growth of aquatic plants. Adding PO4 does little. Adding N does a lot.

    In aquarist thinking, this shows that a healthy established root systems can and do dramatically increase the N load the tank can handle..meaning you can add a lot more NO3/NH4(fish or otherwise), and if you remove too much of this, you often end up with algae.

    So this is maybe why some tanks use far more N than we might think and in our models, might use even more than 1-4ppm per day not so much in plant biomass, rather, bacterial biomass and transformation to N2 gas.

    It also shows clearly that aquatic plants act as "pipes", pumping large amounts of O2 to the lower sediments. So why do we need heat cables or ADA power sand pumic to accomplish this when the roots do it and are far more active, natural and enhance bacteria better?

    Instead we get folks carrying on about O2 levels down in the sediments that have NEVER once done a single wetland redox or O2 profile measurement.
    They do not include the biological factor/s, the plants and bacteria.
    Then they poo poo me and try to find things that contradict:rolleyes:

    The Reddy book in the other link is the best overall book with good pics on how things work. Note, this is a rather slow growing isoetiod plant , so most of our plants grow much faster and vigorous.

    Regards,
    Tom Barr
     
  8. colinsk

    colinsk Junior Poster

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    Playing devil's advocate here...

    What about the places in the substrate that do not yet have roots? Here we have anaerobic conditions and the possible production of H2S.

    Heating the whole substrate will not increase flow as much as un-even heating, or so the thinking goes...

    We also see anaerobic activities in the roots themselves and the production of alcohol via fermentation. (A finding I have never understood.)
     
  9. Tom Barr

    Tom Barr Founder
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    This is easy. In natural sediments, there is organic matter depositing in wetlands. This is added at a high rates.

    The aerobic bacteria munch on this and remove all the O2. This + the organic matter can lead to H2S if the rate is high enough.

    To measure and to quanify this, we use redox measurements in sediments to enumerate this. Everything is tied to the loading of organic reduced carbon into these systems.

    In aquariums, this is not the case because we do not load the system with this much organic matter. And the organic matter we do add, it typically is already very well mineralized and we have ample O2;) So the bacteria do not munch on it, because bacteria or chemical thermal processes have already acted on it.

    In plain sand sediments like the heat cables folks like to use, there's no organic carbon supply, so there's nothing for the bacteria to "eat". So you cannot possibly have any anaerobic conditions.

    This is the fallacy that the cable folks promoted.

    You have to have a souce of reduced carbon and it has to be resuppplied at a high enough rate to prevent the O2 from causing an issue for the H2S bacteria.

    I've never had H2S in any aquariums ever................except when I put a nasty old Aponogetn bulb that was 1/2 dead and it rotted. It added a lot of reduced organic carbon and I put it deep ino the sediment in an old tank.

    We can deep vacuum or uproot a section every so often to fluff up an area to prevent any build up(once a year or so).

    Adding more flow via heat, simpky speeds up the process of accumulation of organic mater from above, but it's pretty well oxidized by the time it gets into our sediment.

    The only data that would ever support cables is Redox data, and it would require plant roots that are normally kept by aquarists.

    Both Tropica and myself, as far as I am aware, are the only folks who have done any sediment Redox data for aquariums. Without that, you cannot say much other than belief and speculation.

    You cannot answer anything really without that. You can turn the cables on/off over time, like many did, and see no significant difference. Which is a rather simple common sense approach to whether something works and is useful for aquariums.

    My point here is more around the idea that good fast growing plants with lots of CO2 etc, will add plenty of O2 to the sediments.

    Use the plants, not cables to do this.
    Far better.

    Regards,
    Tom Barr




    Regards,
    Tom Barr
     
  10. Tom Barr

    Tom Barr Founder
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    Your last question is also straight forward, fermination is done with mostly terrestrial plants that cannot tolerant long, permant submersed flooded sediments. They do that to hopefully make it through a flood, spring melt etc, till the sedimentsry up more.

    All aquatic plants have tubes(arenchymous tissue) that allows O2 from above down into anaerobic sediments. This is defining salinet feature of aquatic rooted macrophytes.

    Regards,
    Tom Barr
     
  11. colinsk

    colinsk Junior Poster

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    Thank you Tom, that is helpful.

    Is any of this published? Can you provide a reference for me?
     
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