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Saharan dust storms sustain life in Atlantic Ocean
Research at the University of Liverpool has found how Saharan dust storms help sustain life over extensive regions of the North Atlantic Ocean.
Working aboard research vessels in the Atlantic, scientists mapped the distribution of nutrients including phosphorous and nitrogen and investigated how organisms such as phytoplankton are sustained in areas with low nutrient levels.
They found that plants are able to grow in these regions because they are able to take advantage of iron minerals in Saharan dust storms. This allows them to use organic or 'recycled' material from dead or decaying plants when nutrients such as phosphorous – an essential component of DNA – in the ocean are low.
Professor George Wolff, from the University's Department of Earth and Ocean Sciences, explains: "We found that cyanobacteria – a type of ancient phytoplankton – are significant to the understanding of how ocean deserts can support plant growth. Cyanobacteria need nitrogen, phosphorous and iron in order to grow. They get nitrogen from the atmosphere, but phosphorous is a highly reactive chemical that is scarce in sea water and is not found in the Earth's atmosphere. Iron is present only in tiny amounts in sea water, even though it is one of the most abundant elements on earth.
"Our findings suggest that Saharan dust storms are largely responsible for the significant difference between the numbers of cyanobacteria in the North and South Atlantic. The dust fertilises the North Atlantic and allows phytoplankton to use organic phosphorous, but it doesn't reach the southern regions and so without enough iron, phytoplankton are unable to use the organic material and don't grow as successfully."
Professor Ric Williams, co-author of the research, added: "The Atlantic is often referred to as an 'ocean desert' because many nutrients, which are essential in plant life cycles, are either scarce or are only accessible in the darker depths of the ocean. Plants, however, need some sunlight in order to absorb these important nutrients and so can't always access them from the ocean depths. They therefore need to find the nutrients from elsewhere. Now that we are able to show how cyanobacteria make use of organic material we can understand more clearly how life is sustained in the ocean and why it isn't an 'ocean desert.'
"These findings are important because plant life cycles are essential in maintaining the balance of gases in our atmosphere. In looking at how plants survive in this area, we have shown how the Atlantic is able to draw down carbon dioxide from the atmosphere through the growth of photosynthesising plants."
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All we "really" are is dust in the wind - ocean apocalypse now
I have read some of the many news reports on the ocean acidification and reef crisis that are presently extant. I beg to differ with the position that reducing our global carbon footprint will help save our ocean bathing beauties, the reefs. It's not that I don't fully support reducing our carbon footprint, I am rather more concerned about the role of the present deadly dose of anthropogenic CO2 already in the air on its way to our surface ocean waters. Those hundreds of billions of tonnes of anthropogenic CO2, the bulk of which we've prescribed and put en route in the past 75 years, is slowly dissolving into the surface ocean. By most accounts CO2 in the atmosphere takes on the order of 200 years to equilibrate with the surface ocean. Hence the pH drop we've been recording is just the proverbial tip of the dry-iceberg.
As the surface ocean absorbs the rest of this deadly dose, regardless of whether we emit more which we surely are doing, the acidification process already destined to occur is more than sufficient to change ocean ecology in far wider and disastrous fashion than merely scalding the bathing beauties at the shore. In fact the devastating effects CO2 has on the ocean is not proceeding only via H2O+CO2=H2CO3 (carbonic acid), there is a secondary reaction wherein CO2 is enhancing the greeness of the planets dry lands. There is is a major benefit our high and rising CO2 delivers to droughty grasses who are losing less water via evapotranspiration, remaining green and growing bushier each spring, and as such are superior ground cover thus reducing topsoil loss in the wind. Tragically that dust in the wind is the major source of vital mineral micronutrients for the open ocean. Prophetically it seems, all we really are is dust in the wind.
So as our reef beauties cry out and dissolve like Dorothy's wicked witch in our acidifying oceans, the acidification will certainly continue for at least another century unabated even if we never emit another molecule of fossil CO2 into the air. At the same time as the oceans suffer this chemical shock treatment, like those we give our swimming pools, they will continue as well to lose their photosynthetic capacity to counter this onslaught. The loss of net primary productivity, NPP, is reportedly 17% in the North Atlantic, 26% in the North Pacific, and 50% in the sub-tropical tropical oceans.
We can find the fundamental proof of the depth of this problem by considering it from the point of view of basic chemical thermodynamics. Indeed we have expended a hundred terrawatts or so burning fossil carbon to put that deadly dose of CO2 into our atmosphere and ocean. No trivial energy savings will serve to counter its certain first principals chemical effects. We can still trust in what the Second Law of Thermodynamics teaches us in that one must balance equations energetically. If we are to address a problem created by terrawatts of energy we must devote terrawatts of energy. In this case those curative terrawatts better be emission free or we are lost.
So where is there a source of emission free terrawatts of curative power we can devote to saving the oceans and help restore the balance of Nature? It is of course ONLY available from photosynthesis and therein lies the course we must chart to restore our oceans as we must surely not simply imagine the damage we've prescribed can simply be ignored and start from the present mortally wounded state. No mere conservation ethic or effort will suffice, we are far to far over the tipping point for that to work. We must replenish and restore ocean photosynthesis for there in the vast living ocean expanse the terrawatts of power, solar power, can be found and used to compete with the H2O+CO2=H2CO3 reaction. There in lies hope if we act now to assist the ocean plants, phyto-plankton, to convert CO2 in the ocean to life instead of death. Without replenished mineral micronutrients, without our determined efforts to administer the antidote, life in the oceans, and on this small blue planet, will surely revert to the cyanobacterial state from whence it came.
If you are a religious person you might liken what we need to do as seeking absolution for our sins of emission by our acts of contrition and ecorestoration, otherwise the path to perdition is that of dissolution of those sins into dying oceans.
Planktos Science
San Francisco
www.planktos-science.com
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