Zinc, Sunflowers, and the Periodic Table of Death & Mystery

Zinc (Zn) is a German word derived from the Persian word “sing”, which means stone. Isn’t that lovely? And while it was officially discovered as an element in 1746, Greeks and Romans have known about it for a couple thousand years (1). A silvery-white metal, Zn tarnishes to a pretty blueish tinge. It’s fairly abundant, making up 0.004% of the earth’s crust, and Zn is primarily used to galvanize other metals so they don’t rust. That means zinc-galvanized stuff—like the metal in cars, buildings, ships—lasts for generations (2). Super-duper. Wonderful.

What the heck is galvanize?

The American Galvanizers Association has ALL the answers. There’s even a movie (3). Galvanizing is literally dipping fabricated iron and steel into a hot zinc dip (Zn melts at 419°C, 787°F) and was named after an Italian, Luigi Galvani, in 1772. He figured out the chemistry of how Zn coats and heals the metal it covers. Hot dip galvanized metals are EVERYWHERE, even in zoos. Watch the movie. It’s 7 minutes of your life you won’t get back, but you’ll have something talk about at family dinners instead of politics.

Zn is called the healthy metal because living creatures use it in a score of different enzymatic processes important for growth and survival (1). In fact, we have from 1-2 grams of Zn in our bodies right now, and the FDA suggests an intake of ~8-12 mg/day. Zn is even in over-the-counter medicines that are supposed to slow or stop us getting sick from colds by blocking rhinoviruses from binding to the cells in our noses. Unfortunately, the side effects like stomach upset, loss of taste, and sometime even the complete loss of the ability to smell, outweigh the positive results (4). And too much Zn is really bad. Like carcinogenic bad with chronic exposure. But where would the average person get chronic exposure of Zn?

How about environmental contamination, especially of water and soil? Which brings us back to DEATH and MYSTERY.

The MYSTERY part is easy. The seed for The Third Warrior, the second book in the Nicky Matthews Mystery series, came from a terrible toxic waste spill from the abandoned Gold King Mine in southern Colorado. Briefly, contractors told the Environment Protection Agency, who had taken over clean-up, that the abandoned mine was at risk for a blowout of contaminated liquid (notice how it wasn’t called water), so the on-site manager halted work until the Bureau of Reclamation could inspect the mine. THEN the original manager went on vacation and his acting replacement went ahead without the inspection. Result? A breach of 3 million gallons of thick orange-yellow liquid into Cement Creek which reached the Animas River within 24 hours. The Animas River’s pH dropped from 7.8 to one hundred times more acidic 5.8 for a day or two (5) and the toxic plume polluted the river for miles and miles, affecting groundwater, crops, and cattle on the Navajo reservation in northern New Mexico. Clean-up and lawsuits are still ongoing.

Now comes the DEATH part. The toxic spill contained a jumble of heavy metal contaminants: cadmium (Cd), lead (Pb), beryllium (Be), iron (Fe), copper (Cu), and, of course, Zinc (Zn) (6). This allows us to loop back to chronic environmental exposure in water and soil. Since clean-up of heavy metals is expensive, invasive, inefficient, and energy intensive, people look for better methods of extraction. That’s where sunflower (Helianthus annuus) phytoremediation comes in. Phyto, by the way, is Greek for plant.

Sunflowers are considered hyperaccumulators of soil and water contaminants (7). They phytoextract the metals naturally and sequester them in roots, stems, and leaves—even seeds, which are a good source of Zn (8). Since sunflowers are an annual, fields can be planted every year, then harvested in the fall and incinerated or even used as biofuels. The heavy metal containing ash is concentrated and disposed of safely. Soil is then tested for continued contamination and replanted as necessary. High soil concentrations of heavy metal contamination can still harm plant growth, so breeding and engineering to create high-tolerance plant cultivars are ongoing.

Huge sunflower field and beautiful colorful sunset sky above them

But it’s not just sunflowers that can be used as phytoremediators. Over 50 different kinds of plants plus mycorrhizal fungi have been tested for uptake of heavy metal contaminants. Plants tested include Nicotiana (tobacco)(9) and Cannabis (marijuana)(10). Yeah, and people burn the leaves and buds and suck in the smoke. Turns out studies have shown that smokers of both type of plants accumulate heavy metals in their bodies. Not quite sure what that would be called. Anthroporemediation?

As always, these are my own opinions based on my biases, knowledge, and understanding, and the websites I’ve linked are in no way a product endorsement.