Topic Posting – Chemistry 105, College of Marin, California
March 8, 2006

 

If it were not for the electrical attraction between ions of opposite charge, and their interaction with big multicellular organisms with roots that we call plants, we would not be here. This is what I discovered by reading Chapter 15 in Conceptual Chemistry by John Suchocki.

What caught my attention was the description of the neat chemistry going on underground by which plants manage to release certain desired nutrient atoms and molecules from the grip of soil and humus particles which are holding onto them (electrically) and then absorb them into their massive multicellular system through their delicate root hairs. The grip holding the nutrients to the soil is the ionic bond.  And it is the action of another ion, hydronium, produced as a direct result of the life process of the plant, which serves to dislodge those absolutely vital nutrients from their position and make them available to the plant.

How does it work? For reasons that are beyond my current state of knowledge, the particles of soil (which vary in size and according to the type of ‘parent’ rock along with the quantity of humus) are negatively charged on their surface. This negative charge attracts and holds tight many different elements in ionic form such as potassium, magnesium, calcium, ammonium, (and several more) which are carrying a positive charge. There these positive ions and vital nutrients would remain—until washed away by heavy rains, and made forever unavailable to the hungry plant—but for the intervention of hydronium which is a positively charged ionic compound of 3 hydrogen atoms bound with one oxygen atom: H3O+.

How does the hydronium get introduced to the soil microenvironment? It arises as a result of chemical reactions in the water of the soil following the plant roots’ release of carbon dioxide, CO2 produced as a result of respiration by the plant (just as we release carbon dioxide from our process of respiration). CO2 is also released by decaying plant and animal and microbial life forms after death. This carbon dioxide reacts with water molecules to become carbonic acid and there is then another reaction, this time of the carbonic acid with water, to create two different ions – bicarbonate (negatively charged) and hydronium (positively charged). The hydronium’s charge works to dislodge the smaller positively charged ions – displacing them and becoming the new partner to the soil particles—and suddenly there are some free elemental nutrients, which can be absorbed into the tiny hairs of the plant root.

The plant draws its life – pulling in the vitally needed magnesium for its chlorophyll molecules which interact with sunlight to perform the first part of photosynthesis, pulling in the vitally needed nitrogen in the form of ammonium ions for its production of proteins, amino acids, nucleotides and coenzymes etc, pulling in the potassium needed for osmosis and ionic balance, the opening and closing of its leaf stomata—and the list goes on. In this way, carried away from their attachment to soil particles and into the dynamic living system of the plant, eight of the 14 vital ‘inorganic’ nutrients for plants are drawn in to sustain the astoundingly complex cell-based life of the plant. As plants are the ‘producers’ and we are the ‘consumers’ whose lives rest upon plants or on the animals that eat plants, we too draw our life out of this chemically coordinated flow of electrical charge taking place beneath the ground.

If one then expands the picture of chemistry underground to witness the marvel of a symbiotic relationship between certain bacteria which can break down the extremely tough atomic structure of nitrogen, and certain plants which provide them with nutrients in return, one begins to sense the profoundly inter-related nature of life. We have identified the categories of organic and inorganic for many sound reasons, but when we put together all the different ways that nutrients for life’s processes are produced and obtained, we grasp a powerful lesson about how humans must learn to live successfully on Earth. By taking a close up look at the chemistry and biology moving flawlessly together to build up and sustain life – above and below ground – we can learn the ways of nature that we too must emulate if we are to ‘fit’ in the environment long-term.

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