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The nitrogen problem?

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  • Steve Dodd
    [Not sure I completely understood this, but given the tendency toward large scale systems thinking on this list, I thought you all might find it intriguing
    Message 1 of 4 , Jul 29, 2004
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      [Not sure I completely understood this, but given the tendency toward
      large scale systems thinking on this list, I thought you all might find
      it intriguing -SD]

      ----- Forwarded message from klaatu -----

      From: klaatu
      To: "Discussions of Die-Off, PeakOil, The Singularity, etc" <the_singularity@...>
      Subject: Re: Touching the void
      Date: Thu, 29 Jul 2004 12:38:06 -0400 (EDT)
      Old-Subject: Re: [The_Singularity] Touching the void
      Sender: the_singularity-bounces@...

      On Thu, 29 Jul 2004, Steve Dodd wrote:

      <snips>

      >
      > As the human population explodes, other species are running out of food
      > and space. But, Tim Radford reports, it was never supposed to be that
      > way
      >
      > Thursday July 22, 2004 The Guardian
      >
      > http://www.guardian.co.uk/life/feature/story/0,13026,1265899,00.html



      > [ ... ] There is scatter on the graph: there are always,
      > for instance, more herbivores than carnivores; more prey than predators.
      > A leopard and a gazelle are about the same mass but gazelles probably
      > outnumber leopards by 100 to one. Even so, the rule holds true, except
      > for humans. If there is a biological rule about population size, humans
      > have broken it. How did we do it?
      >
      > "Well, we are able to do that because we are able to use fossil fuel. We
      > sustain our society and our population density and are able to live in
      > places at densities that are actually unsustainable without an energy
      > subsidy," Lawton says.
      >
      > "And what that allows us to do is grow food, because our crop production
      > is oil-powered; we rely hugely on fossil fuel to grow food, over huge
      > areas of the world. The reason you and I can sit here having a lively
      > intelligent conversation without having to worry where our lunch is
      > going to come from is because modern farming uses fossil fuel to
      > increase hugely the efficiency with which an individual farmer can
      > produce food for thousands of people. We are therefore able to use this
      > fossil fuel subsidy to destroy the habitats of most of the other
      > creatures on the planet."

      I mentioned this elsewhere online just the other day...

      A friend of mine had pointed out that he wasn't entirely sure about the
      accuracy of his statistics and couldn't instantly point to a citation, but
      his belief was that something like 70% of the nitrogen fixed in humans and
      their livestock had been fixed since the mid-20th century, by the Haber
      process.

      I went on, in my UseNet article, to wonder what might happen if there were
      some sort of crash of technical civilization. Regardless of what happened
      to people, the impacts of "nitrogen pollution" on the ecosphere might be
      rather amazing. Witness the results of "nitrogen saturation" and "nitrogen
      pollution" on the Gulf of Mexico and the Chesapeake Bay; they have rather
      large "dead zones" from which oxygen has been almost totally, or totally,
      depleted. This causes a great deal of disruption in the local ecologies as
      you might expect.

      I made an estimate of something like 40% of extant mammalian biomass being
      human-produced (Haber-process fixed nitrogen) and I thought it a bit high.
      I'm astonished by this article's estimates which make my own estimate
      appear to be low by at least an order of magnitude.

      Already, humanity controls or diverts some 54% of the non-saline/non-ice
      hydrosphere flows. But to discover that we may have actually impounded
      significant fractions of the atmosphere's nitrogen is worrisome. We may or
      may not have fixed so much nitrogen that the "global protein budget" -- a
      concept coined at this instant by me -- might be double of what could
      possibly be sustained on natural annual energy inputs alone. In effect, we
      might very well have been, albeit inefficiently, converting fossil fuels
      to protein at a level far beyond unsupportable. What will happen to all of
      that nitrogen and those organic nitrogen compounds one civilization
      crashes and we can't continue to fix such huge volumes with the
      electricity-based Haber process? We'll definitely all need to be on the
      Atkins diet, and in all likelihood the only meat left to eat will be that
      of other carnivores, as the herbivores might very well all starve is
      nitrogen of decomposition is released back into the atmosphere instead of
      being plowed into the ground as fertilizers, or runs off into the dying
      oceans, which would then be even less able to act as a sink for
      carbon-dioxide in the form of calcium carbonate seashells.

      Regards,


      <snips>
      --
      "We look through a glass but darkly:
      What we see is more colored by our beliefs,
      than what we believe is colored by what we see."
      _______________________________________________
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      ----- End forwarded message -----

      --
      Home+FOAF: http://www.loth.org.uk/ * PGP: 201A57B6 * Original portions
      © 2004 Steve Dodd * "I'm not falling apart, I'm coming together." *
      Appreciated this message? - http://www.loth.org.uk/tipjar/ * PNAMBC *

      "We have the beginning of a new age. The earth 'gets a new skin.' Better
      still, it finds its soul." -- Teilhard de Chardin
    • XK SAZ
      ... t his belief was that something like 70% of the nitrogen fixed in humans an= d their livestock had been fixed since the mid-20th century, by the Haber
      Message 2 of 4 , Jul 29, 2004
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        > A friend of mine had pointed out that he wasn't entirely sure about the
        > accuracy of his statistics and couldn't instantly point to a citation, bu=
        t
        > his belief was that something like 70% of the nitrogen fixed in humans an=
        d
        > their livestock had been fixed since the mid-20th century, by the Haber
        > process.

        I'm not sure what "nitrogen fixed in humans" means...
        but I found this.


        Nitrogen molecules occur mainly in air. In water and soils nitrogen can be=
        found in
        nitrates and nitrites. All of these substances are a part of the nitrogen c=
        ycle, whereas there
        are all interconnected.

        Humans have changed natural nitrate and nitrite proportions radically, main=
        ly due to the
        application of nitrate-containing manures. Nitrogen is emitted extensively =
        by industrial
        companies, increasing the nitrate and nitrite supplies in soil and water as=
        a consequence
        of reactions that take place in the nitrogen cycle. Nitrate concentrations =
        in drinking water
        will greatly increase due to this.

        Nitrates and nitrites are known to cause several health effects. These are =
        the
        most common effects:

        - Reactions with haemoglobin in blood, causing the oxygen carrying capacity=
        of the blood
        to decrease (nitrite)
        - Decreased functioning of the thyroid gland (nitrate)
        - Shortages of vitamin A (nitrate)
        - Fashioning of nitrosamines, which are known as one of the most common cau=
        ses of
        cancer (nitrates and nitrites)

        But from a metabolic point of view, nitric oxide (NO) is much more importa=
        nt than
        nitrogen alone. In 1987, Salvador Moncada discovered that this was a vital=
        body
        messenger for relaxing muscles, and today we know that it is involved in t=
        he
        cardiovascular system, the immune system, the central nervous system and t=
        he peripheral
        nervous system. The enzyme that produces nitric oxide, called nitric oxide=
        synthase, is
        abundant in the brain.


        Although nitric oxide is relatively short-lived, it can diffuse through me=
        mbranes to carry
        out its functions. In 1991, a team headed by K.–E.Anderson of Lund Univers=
        ity Hospital,
        Sweden, showed that nitric oxide activates an erection by relaxing the mus=
        cle that
        controls the flow of blood into the penis. The drug Viagra works by releas=
        ing nitric oxide
        to produce the same effect.
      • XK SAZ
        nitrogen cycle, the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and
        Message 3 of 4 , Jul 29, 2004
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          nitrogen cycle, the continuous flow of nitrogen through the biosphere by the processes of
          nitrogen fixation, ammonification (decay), nitrification, and denitrification. Nitrogen is vital
          to all living matter, both plant and animal; it is an essential constituent of amino acids,
          which form proteins of nucleic acids, and of many other organic materials.

          Nitrogen Fixation

          Although the earth's atmosphere is 78% nitrogen, free gaseous nitrogen cannot be utilized
          by animals or by higher plants. They depend instead on nitrogen that is present in the soil.
          To enter living systems, nitrogen must be "fixed" (combined with oxygen or hydrogen)
          into compounds that plants can utilize, such as nitrates or ammonia. A certain amount of
          atmospheric nitrogen is fixed by lightning and by some cyanobacteria (blue-green algae).
          But the great bulk of nitrogen fixation is performed by soil bacteria of two kinds: those
          that live free in the soil and those that live enclosed in nodules in the roots of certain
          leguminous plants (e.g., alfalfa, peas, beans, clover, soybeans, and peanuts). Among the
          free-living forms are species of Clostridium, discovered c.1893 by Sergei Winogradsky,
          and Azotobacter, discovered c.1901 by M. W. Beijerinck. Both Clostridium and Azotobacter
          are generally present in agricultural soils, and both are saprophytes, i.e., they use the
          energy from decaying organic matter in the soil to fuel soil processes, including nitrogen
          fixation.

          Bacteria that live in the roots of legumes are of the genus Rhizobium, first isolated c.1888
          by Beijerinck. These rod-shaped bacteria enter the roots chiefly through the root hairs and
          then work their way to the inner root tissues. There they stimulate the growth of tumorlike
          nodules. Within the nodules the bacteria develop into forms called bacteroids, which live in
          a symbiotic (mutually beneficial) relationship with the green plant. The bacteroids take
          carbohydrates from the plant for energy to fix nitrogen and synthesize amino acids; the
          plants take the amino acids elaborated in the nodule to build plant tissue. Animals in turn
          consume the plants and convert plant protein into animal protein. Rhizobia can be found
          free-living in the soil, but they cannot fix nitrogen in the free state, nor can the legume
          root fix nitrogen without Rhizobia.

          The exact biochemistry of nitrogen fixation within the nodule is not yet understood. It is
          estimated that more than 300 lbs of nitrogen per acre (340 kg per hectare) can be fixed by
          fields of alfalfa and other legumes. After a harvest legume roots left in the soil decay,
          returning organic nitrogen compounds to the soil for uptake by the next generation of
          plants. For this reason crop rotation in which a leguminous crop is rotated with a
          nonleguminous one is a common practice for maintaining soil fertility.

          Other Aspects of the Nitrogen Cycle

          Decomposing animal remains and animal wastes also return organic nitrogen to the soil as
          ammonia. Many different kinds of decay microorganisms participate in ammonification.
          The nitrifying bacteria of the genus Nitrosomonas oxidize the ammonia to nitrites, and
          Nitrobacter oxidize the nitrites to nitrates. The nitrates can then be taken up again by the
          green plant. The cycle of fixation-decay-nitrification-fixation can proceed indefinitely
          without any nitrogen being returned to a gaseous state. But still another group of
          microorganisms, the denitrifying bacteria, can reduce nitrates all the way to molecular
          nitrogen. Denitrification occurs only in the absence of oxygen and is not common in well-
          cultivated soils.

          Effects of Artificial Fixation

          Nitrogen fixation can also be accomplished artificially by various methods (see nitrogen).
          Humans annually fix vast amounts of nitrogen for industrial purposes and for use as
          fertilizer. Unfortunately, large-scale legume cultivation and artificial fixation may be
          upsetting the natural nitrogen cycle in the biosphere. There is some question whether
          natural denitrification can keep pace with fixation. For one thing, run-off of nitrate
          fertilizer can cause eutrophication of lakes and streams (see water pollution) and can foul
          drinking supplies. Another environmental problem is that inorganic fertilizers tend to
          depress legume fixation. As a consequence, root tissue remaining after harvest is poorer,
          and thus more fertilizer must be applied the following year.
        • XK SAZ
          http://story.news.yahoo.com/news?tmpl=story2&u=/nm/20040803/sc_nm/ environment_deadzone_dc
          Message 4 of 4 , Aug 4, 2004
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