Willows to the Rescue?

13 Jul

This week John and George sacrificed the usual Friday field work in order to work on our upcoming on-line native plants class to be in play as school starts.  Related to that, I’ve been fretting my second Florida outdoor interest—or let’s say nervous preoccupation—groundwater contamination.  The native plants connection is that millions of landscapers and homeowners who could use native plants with minimal chemical demands, instead spew mind-boggling (perhaps literally) herbicides, fungicides, and insecticides all over the ground, to percolate into the ground-water, which we later call tapwater.  (No, they do not get everything out.)

Salix caroliniana in flower by John Bradford.

Salix caroliniana in flower by John Bradford.

The situation is substantial and worsening, and in my humble opinion is under-publicized.  Somebody ought to start a blog (or a consumer revolution).  It is a joy to see an occasional piece in the PB Post and other Florida papers on this topic.  Yet hardly anybody cares, and a fine chemically tended lawn is a sign of responsibility and solid social status.  Just ask the HOA.  Okay, this paragraph could fill a book.  And such books exist, recently “What’s Gotten Into Us” by McKay Jenkins (2011).

Environmental author Steven Lerner—who has his own books on toxic stinkholes with depressing Florida examples—took a special interest in Tellevast, Florida near Sarasota.  The problems there are not pesticides, but rather defense industry wastes and spills, especially the chlorinated organic solvent called TCE (trichloroethylene) as well as beryllium and varied additional organic solvents.  Chlorinated organics turn up often on lists of carcinogens, for instance, the insecticide DDT, the herbicide 2,4-D, and dioxin.  They are the main rascals in Rachel Carson’s Silent Spring.

TCE is one of the worst U. S. groundwater contaminants.  (The likewise chlorinated herbicide Atrazine is a rival.)   TCE causes mutations and apparently cancers.  It deteriorates into even-more-carcinogenic vinyl chloride.  Sources of TCE pollution include defense-industry factories and aviation facilities.  My first known exposure was in Dayton, Ohio where TCE and additional solvents from Wright Patterson Airbase had visited the local groundwater.  The city erected air-strippers, which are water ventilation towers to transform water pollution to air pollution.

The citizens of Tellevast reportedly suffer disproportionately from cancers and medical troubles ascribed to TCE and other contaminants in the water beneath their feet.  The defense contractor Lockheed Martin owns the facility and is on the hooks for dealing with it.

Well, that’s all nasty, scary, debated, and politicized.  But this is a native plants blog, so, how ‘bout it?   Right!  This all brings us to the Willow Family, the Salicaceae.  The main Florida members of this family are poplars, cottonwoods, and a few willows.  The species in our local area and native to Tellevast is Carolina Willow (Salix caroliniana).

Willow leaves by JB

Willow leaves by JB

How do you oust chlorinated organic chemicals from groundwater without merely redistributing the poison?  There are several approaches but no silver bullet.  The approach of interest in our botanical blog is using poplars and willows for “bioremediation,” to disarm, alter, remove, and sequester the poisons.  It is all experimental, and truly promising at least under controlled conditions.  Poplars and willows are diverse, worldwide, resistant to toxins, easy to propagate, fast-growing, potentially deep-rooted, and able to suck up a lot of water.  They do nuke chlorinated organic pollutants.

Researchers are looking into the comparative efficacy of different species and hybrids.  The cast of species is important because different species flourish in different regions.  One size does not fit all. Poplars outshine willows, yet our own Carolina willow has made the defense team.

Trees detoxify water in multiple ways.  For starters, our green helpers suck up the polluted water through their roots and then alter and imprison the evil molecules in woody tissues.

More remarkable tools in the tree toolbox are enzymes called dehalogenases (dee-HAL-oh-jen-ase) able to clip chlorines off of organic molecules.  That’s almost magic, and to make more useful proteins there’s genetic engineering.  There are already GMO poplars engineered for various growth characteristics, so enzyme enhancement is no huge stretch. In fact, one poplar hybrid is already bioengineered specifically to degrade TCE and other organics.  And get this:  the gene engineered into the trees is a human gene, producing an enzyme to metabolize the carcinogenic molecules.

Risks include the possibility of sequestered toxins re-escaping from products made later from the trees.  Would you want to mulch your veggie garden with their chips?   Surprise chemical breakdown byproducts could emerge, and maybe even ecological misbehavior by the bionic trees.

Similarly armed with dehalogenase enzymes are bacteria, and they are partners in the clean-up and are targets for genetic engineering, which is occurring relevant to TCE.  Bacteria are easier and faster to engineer, incubate, and establish than trees.

Time to wrap this up.  In short, our groundwater is full of bad stuff.  Some of it comes from landscape and turf products where a shift to native species and less lawn would diminish the uckies. Most Florida shallow groundwater and some deep groundwater carries more contaminants than we’d like to know…or drink…even after “purification.”  The solvent TCE is a chlorinated organic goblin.  Tellevast floats 6 feet above TCE-laced water.   We’re not quite ready to plant the town with GMO willows.  But there’s hope for green remediation down the road.  So what the heck, we can load the groundwater up with carcinogens today and let our mutated great-grandchildren plant magic willows.



For an early in-depth look at the Tellevast situation:

For about bioremediation and TCE:


Posted by on July 13, 2014 in Carolina Willows


Tags: , , , ,

19 responses to “Willows to the Rescue?

  1. SmallHouseBigGarden

    July 13, 2014 at 8:58 pm

    So well explained! Wonderful education on a serious problem. Thank you for this!

    • George Rogers

      July 14, 2014 at 10:19 am

      Loved your wacky-doodle passionflower! That must have taken some doing! Congratulations on your SHBGMO (small house big garden modified organism).

  2. Martin

    July 14, 2014 at 5:56 am

    Very nice, George, very nice.

    • George Rogers

      July 14, 2014 at 10:27 am

      Thanks Martin. If the weather ever becomes inviting, gotta get up to the park. Been awhile.

  3. Diane Goldberg

    July 14, 2014 at 8:39 am

    I’d rather see bacteria absorb the toxins than plants, because I’d worry about the bees getting the toxins in the pollen they return to their hives & in the honey we eat. What native ground covers do you recommend instead of grass?

    • George Rogers

      July 14, 2014 at 10:15 am

      Diane, Well, when it comes to chemicals in the ecosphere, surprises are for sure a worry, and willows are insect-pollinated. When chlorinated organics go up into a tree, the chemistry must be complex. Some toxins are probably destroyed effectively by bioremediaiton, but others are no doubt merely sequestered in the wood hopefully altered benignly, or altered or broken down into smaller organochlorines, not necessarily harmless. How about when we inject insecticides into trees to “keep the insecticides out of the environment”? I don’t trust those to utterly fail to get into the environment permanently. As you know, the worst-case and much debated king of the nectar-poison concerns is the neonicotinoid family of pesticides, especially imidacloprid, so popular these days to kill insects. We’ve been clever with our technology making pesticides so water-soluble they can wind up even in the nectar, and pretty much anywhere it is wet. Atrazine is a fun Google project in the wet connection. And there are other super-water-soluble bee-worrisome products out there with actual or potential similar risks. We’ll be seeing more and more no doubt. I realize that colony collapse disorder is controversial, with bee-huggers like me happy to ban imidacloprid today, but with divergent valid (and invalid!) viewpoints out there. We’re all probably too insecticide-brain-damaged to get it right anyhow.

      A weird personal psychological quirk, but I’m not strong on recommending specific plants for landscaping situations. Call it a quirk, or call it more accurately incompetence. My favorite sources of insight (and plants) on that topic are the local native plant nurseries listed at

      • Diane Goldberg

        July 14, 2014 at 3:52 pm

        I like Creeping Charlie, also called Mat Lippia (Phyla nodiflora) & Sunshine Mimosa (Mimosa strigillosa). I’m letting them infiltrate & take over my lawn. It’s nice ’cause you can walk on them & you don’t have to mow them. I hope to eventually have them & no grass at all.

        Reply by GR: Yes, thank you, I like them too. I’ll bet they look attractive. Groundcovers are always a challenge in this area—so much easier up north.

  4. Mary Hart

    July 14, 2014 at 10:47 am

    Absolutely fascinating- in UK I’m glad to say we’re somewhat better than USA in opposing a number of chemical horrors (DDT banned long ago, I’m pretty sure) but there are too many still around. We have plenty of Salix varieties, especially important as the prime ingredient in cricket bats!!

    • George Rogers

      July 14, 2014 at 12:31 pm

      Hi Mary, DDT banned here too, but plenty still around. If you look at local water sampling data our groundwater loaded with DDT (or at least its derivative DDE). And three cheers for tighter pesticide controls in Europe, including ban in imidacloprid despite opposition. Oh boy, this coming from the Chair of the Horticulture Dept. Who would think you could get into controversial waters in Horticulture other than “how do you prune an Ixora?” I’m probably expected to say spray spray spray…but truth is truth.

      Forgot that cricket bats are willow—light and won’t split—right?

  5. theshrubqueen

    July 14, 2014 at 11:40 am

    What do you think about bioretention? In regards to what happens after all the junk is absorbed into one place? Then what happens?

    • George Rogers

      July 14, 2014 at 12:49 pm

      I’m no toxicological chemist. But my opinion is that it is all in the details, specific cases, perceived outcome odds, and balanced costs and benefits. With unknowns to blur the picture. Clearly if you sequester a toxin (or in my very recent experience a bad dog) it may return later to gitya. If its lies in the mud, or resides in wood, or settles in my fat cells I may experience the ghost of toxins past. Fortunately, a lot (not all!) modern pesticides are becoming less persistent. Don’t cheer—it’s not that good.

      With bioremediation—depending on details details details—the idea is that some of the toxic molecules are altered to less harmful forms by metabolic and biological processes. When a tree takes in chlorinated organic molecules and incorporates them into its own tissues the chlorinated molecules are altered, maybe not 100% benign, but at least hopefully no longer a loaded carcinogenic-mutagenic cannon. When dehalogenase enzymes nip off a chlorine, the chlorine atom is not destroyed, but with luck its next molecular manifestation is less dangerous than ETC or dioxin. Not all chlorinated molecules are equally nasty. I mean, I do not like bleach, but I’d rather be around bleach than DDT or Atrazine. (I think.) Also, for better or worse, chlorine may volatilize from the soil microbial context or transpire out of the foliage and blow away in a less toxic form. (Yes, with much pollution there is no “away.”)

      We could have a fun conversation about all that junk retained in one place with a chat about landfills. As the landfill staff would tell us accurately, that’s OUR junk, THEY don’t want it and you gotta do SOMETHING….but an interesting little Google project is to look into where the landfill leachate (garbage juice) goes.

      • theshrubqueen

        July 14, 2014 at 1:09 pm

        Yum, garbage juice. The bioretention always disturbs me because there is no allowance for age or use. It just sits there and whatever happens, happens.

        It has to get full at some point. Engineers, I guess will figure it out later.

  6. George Rogers

    July 14, 2014 at 1:14 pm

    I was fascinated with the intended PSL plasma-arc garbage-vaporization unit. That was going to be a sight to see, incineration on steroids. Then they couldn’t afford it. Dang…

  7. Diane Goldberg

    July 14, 2014 at 4:00 pm

    I was also interested in the PSL plasma-arc garbage-vaporization unit. Besides the cost issue, I think there was also a question about the amount of air pollution it would create.

  8. George Rogers

    July 14, 2014 at 5:19 pm

    yes, no doubt

  9. Uncle Tree

    July 14, 2014 at 7:19 pm

    I don’t know what to say after reading all this bad news. New or old,
    it’s not good news. I am glad to see people like you have at least
    somewhat of a handle on the ongoing situation. I’m also encouraged
    to know we have some possible organic remedies to ease the onrush
    of chemical disease. Green lawns — so hazardous, so time-consuming,
    and so, too so desired. Yes, I’ve grown to love the look, but I’m a renter
    now, and don’t have to waste my precious time on such trivial pursuits.

    Thanks for informing us and the world at large, good sir! 🙂

  10. George Rogers

    July 14, 2014 at 7:55 pm

    Uncle Tree, Such a pleasure to see you here. Thank you.

  11. FeyGirl

    July 22, 2014 at 1:24 pm

    EXCELLENT article — I agree, this needs to be disseminated much more! I had no idea that willows and poplars could counter the (growing) terrible effects of groundwater contamination. It really is fascinating. Hmmmm… Re-blog?

    • George Rogers

      July 22, 2014 at 1:33 pm

      FG–thanks! Let’s hope they can help. I have a sense that “if all truth were known” the FL groundwater story would not be pleasing. Keep up the explorations!


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