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Like a Cold War relic, the southeastern side of Moffett Field is showing its age with long swaths of empty asphalt lots, shuttered military housing and a former McDonald’s that stopped serving burgers years ago.

But amid these drab buildings, there’s an oasis of greenery — a small forest of hundreds of poplar trees tucked between two baseball diamonds.

On a Friday morning, as he does on most days, John Freeman took a walk through the trees, inspecting the leaves for signs of disease or discoloration. It was a routine the 42-year-old had been doing for years, ever since he got permission from NASA Ames officials to plant the trees on an unused dirt lot.

Freeman is no groundskeeper, and his poplar trees are doing more than providing cheerful scenery. In fact, the trees are part of a long-running research program for finding new methods to clean up the chemical contaminants that linger in the area’s groundwater. On any given day, his trees are sucking up about 40,000 gallons of toxic water through their roots and then breaking down the worst contaminants into benign byproducts.

Freeman, a plant physiologist, has become NASA’s lead expert on phytoremediation — using plant life to help clean up pollution. This research is showing promise for providing a cheaper, natural alternative to clean up trichloroethene (TCE), the carcinogenic contaminant found in groundwater flowing under Moffett Field, parts of Mountain View and about 1,000 Superfund sites across the United States.

“We have a number of collaborators and we hope to deploy this technology for everyone,” Freeman said. “Trees have been used for this for decades, but now we’re finding ways to up the efficiencies.”

In August, Freeman and nine colleagues published their phytoremediation study based on the Moffett Field poplar trees in the science journal Environmental Science & Technology. Their research is the first phytoremediation field test of its kind, and experts are hailing it as a potential game-changer for the $2.5 billion market for cleaning up TCE contamination.

James Landmeyer, a U.S. Geological Survey research hydrologist who has closely studied phytoremediation, estimated that the technology highlighted in the study showed promise to cut the costs of groundwater remediation by 75 percent, given the right circumstances.

“The biggest benefit of having the trees pumping water from the ground is you’re able to effectively remediate a much large volume of water and you’re able to do it at a much faster pace,” he said. “This is a cleanup method that’s publicly appealing, effective and it’s not resource intensive.”

Even in antiquity, ancient Greek and Roman scholars noted that certain plants could proliferate in metal-loaded soils near mining excavations. For hundreds of years, human communities have unintentionally dabbled in phytoremediation by consolidating their waste in certain areas, often bogs and wetlands, forcing native plants to adapt to survive.

It wasn’t until the last 40 years that researchers began deliberately working to identify and harness the microbes in plants that break down specific pollutants. In the lab, this idea has shown promise to break down a wide array of contaminants, including petroleum, explosives, metals and coal byproducts.

Freeman and his research firm, Intrinsyx, originally came to Moffett 17 years ago to support NASA space sciences. Starting around 2013, they received a two-year research grant for the phytoremediation study from the National Institute of Environmental Health Sciences. The project gained later funding from NASA, Intrinsyx, and a Colorado-based phytoremediation firm. To date, the research has cost more than $500,000.

For the experiment, the team decided the best spot to plant the trees would be a sliver of land where maps of the Middlefield-Ellis-Whisman Superfund site showed an underground channel of toxic water flowing north across Highway 101. This was a good location because the trees could serve as a firewall across the groundwater, going right between two wells that would serve for analysis, he said.

Poplars were the obvious plant to use, Freeman said. The trees are “water hogs,” each capable of absorbing about 50 gallons a day. Poplars also are easy to uproot and move; they are adaptable and grow easily; and they have deep roots that can bore down into aquifers.

But most important, he said poplar trees are excellent candidates for bioaugmentation, or fortifying the trees with helpful bacteria to help break down specific compounds. Freeman’s co-authors at the University of Washington had previously isolated a poplar microbe called Enterobacter PDN3. This bacteria strain was derived from poplars that had grown at a TCE-contaminated site in the Midwest, and it proved to have a ravenous hunger for consuming the chemical.

Prior to planting, Freeman and his team soaked poplar cuttings in a broth of PDN3 in order to inoculate them with the bacteria. Then, along the southeastern border of Moffett Field they planted about 800 poplars, about half of which had no bioaugmentation, to serve as a control group.

As months passed, the bioaugmented trees clearly had an advantage — they grew taller, with wider trunks and healthier leaves. Meanwhile, the control group’s trees apparently suffered from absorbing too much toxic material, showing stunted growth and withered leaves.

Perhaps most remarkable, the bioaugmented trees showed dramatic results in cleaning up the groundwater. Like a river, the groundwater plume flows in a specific direction, and the research team measured samples from a well upstream from the poplars and another one that is downstream. Trace TCE levels were detected upstream, but after the groundwater passed through the line of poplar trees that pollution was reduced to undetectable levels. In fact, the trees also apparently filtered out various other contaminants, including tetrachloroethylene and dichloroethene.

Sharon Doty, a microbiology professor at the University of Washington who co-authored the study, expressed enthusiasm that the new phytoremediation techniques could be quickly implemented at waste sites across the country.

“By partnering appropriate tree species with pollutant-degrading microbes, we were able to advance phytoremediation dramatically,” she wrote in an email. “The overall method … is so easy and so much cheaper than conventional engineering methods that it can be deployed on the many contaminated sites so far being ignored.”

For many sites around Mountain View, the predominant system for purging these contaminants is a “pump and treat” method, which can cost up to $3 million per site, plus annual operating expenses. NASA Ames operates three such systems.

In the near future, Freeman said he would like to introduce his team’s TCE-fighting trees to office campuses and neighborhoods in contaminated areas.

“We hope this can replace the pump-and-treat systems — those systems are expensive and electric,” Freeman said.

TCE was used as an industrial degreaser and solvent at hundreds of industrial and military sites across the country. In recent years, the chemical has been identified by the Environmental Protection Agency as a carcinogen through any route of exposure. In Mountain View, the biggest risk is via fumes that seep up from contaminated groundwater and build up to unsafe levels inside buildings.

NASA Ames Restoration Program Manager Kimberly Finch told the Voice that the agency will continue pursuing phytoremediation where it is feasible.

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1 Comment

  1. What a promising report!

    I do quibble with the description of an “underground river” because the deeper you look, the more the hydrogeology of that area is characterized by quite discontinuous layers and aquifers. Closer to the surface, there is a general flow of water (and contaminants). Pump and treat systems reach down 100 feet and more, often into deep,isolated pockets of contamination. Still, if these trees can capture the material moving near the surface, that’s good news.

    Question: what are the benign byproducts mentioned?

  2. Ohhh… I love this win/win story about a man who had the skill to think things through and found the kind of solution this world needs. Thanks for printing the story and special thanks John Freeman and his colleagues. I love you all.

  4. Jeff: According to the publicly available abstract at http://pubs.acs.org/doi/abs/10.1021/acs.est.7b01504, “The inoculated trees excreted 50% more chloride ion into the rhizosphere …”. Since common table salt is sodium chloride, I’m guessing these chloride ions are the “benign byproducts” mentioned. (Rhizosphere, which I had to look up, is the region around and affected by the tree’s root system.)

  5. In reply to comments from Man.
    I personally believe you are mistaken on many topics you’ve discussed above.. EPA has clearly offered guidance and approval for hundreds of such projects that have been implemented and were successful Across the Nation more information can be found on their clue-in.org EPA website search tce phytoremediation using poplar. The ability to integrate these trees into neighborhoods and local businesses is key! large-scale swaths of land do not need to be cleared… rather trees can be interplanted with existing structures quite easily because they use groundwater little or no irrigation is required after 2 years and the trees seem to reach large enough height size to be effective within 4 to 5 years. this is a long-term solution that can be integrated by the public. poplar trees can live up to 50 years. And if they are in the way of future development they are cut off while dormant in winter and easily replanted at which time they root in the spring and re-establish themselves seeking groundwater with new taproots immediately. There are many Legacy sites that are undeveloped that could also use this technology and as a phyto barrier retarding and removing the movement of plumes towards Office Buildings and the bay this technology should be clearly adopted. In my professional opinion.

  7. the endophytic bacteria help to degrade the tce Down to chloride internally. Reducing risk associated with such VOC. the EPA stated in Report the soil has a better transpiration of vocs, than poplar trees, which is negligible at best. While the trees are not perfect for all Sites they do help compliment some of the existing countermeasures that are already in place.

  8. Clearly you did not understand the science behind this and there’s no point in arguing all of these points that are completely manufactured . you have no understanding of the system or the science whatsoever. Genetic manipulation what genetic manipulation? this is a native bacterial endophyte that naturally lives inside the tree it is not a GMO.

  9. John Freeman, thank you for coming to this forum to discuss your work! I think it sounds very promising. Please do not be discouraged by whatever it is that the other commenter is on about. I think this idea sounds so simple, affordable, with very few downsides, that it’s one of those “it could never work” kind of things – except it does, so far! Hopefully this can be used in locations around the city where it makes sense.

  10. Around the city where it makes sense would be helpful I agree.
    EPA offers the following in their clu-in guidance in regards to concerns over volatilization in this approved TCE ground water phytoremediation method.
    “” 2.3.5 TCE Volatilization
    Understanding TCE volatilization rates in poplar trees is critical for this technology to gain widespread acceptance amongst hazardous waste site managers and regulators. There may be concern if the trees are transpiring high concentrations of TCE into the atmosphere, where the pollutant becomes an air quality concern. Proponents of phytoremediation argue that VOCs will volatilize from the groundwater, through the soil, and into the air in the absence of trees. For example, plants will invade sites that are left unattended for extended periods of time, and invasive plants may evapotranspirate the contaminant. That being the case, there would be some evapotranspiration in the absence of a treatment strategy. Phytoremediation schemes would only accelerate the process of volatilization that occurs naturally. Still, volatilization concentrations are decreased by a number of factors, such as exclusion of nonpolar compounds at the roots. According to Davis et al. (1996), “Very few contaminants are sufficiently water soluble, non-toxic to plants, and volatile enough to reach atmospheric concentrations that would be of concern by [evapotranspiration].”
    Despite the fact that evapotranspiration rates are still unclear, Davis et al. (1996) used energy input estimates to calculate a maximum transfer rate of TCE to the atmosphere. They predicted a maximum transfer rate of 10 g/m2/day. This estimation assumes that the water is totally saturated with TCE at 1.5 g/L and the TSCF of TCE is 0.67, based on the equations of Briggs et al. (1982). Using a more realistic groundwater concentration of 1-15 mg/L TCE and a mixing height of 100-300 meters in the atmosphere, the investigators estimated that transfer to the atmosphere would be 4 to 6 orders of magnitude smaller than the maximum. The result is a very low air concentration of TCE downwind in a worst case scenario.””
    It’s been shown that when in the atmosphere hydroxy radicals quickly break down and destroy tce. Apparently voc tce inside of buildings, in basements and in groundwater are the most concerning locations. More information found https://www.atsdr.cdc.gov›tp19-c6

  11. Assuming that the undegraded tce is automatically being volatilized by the tree is the flaw in your logic. EPA Report states a large amount TCE sticks inside tree to cell walls and is not volatilized. Then there is the other many different native species of bacteria also in the tree with lesser TCE degradative rates in addition to the selected native non-GMO endophyte. Taken together with the 500 mg/kg increase in the soil chloride Associated rhizosphere adjacent inoculated tree roots this means vast majority TCE being degraded internally to chloride and exuded through root efflux proteins into soil where becomes table salt NaCl. Furthermore to EPA point TCE already going into air due to soil and water volitilization rates inherent on these TCE contaminated sites.

  12. In response to this report, and Doug Pearson, I think it is way premature to think the TCE pollution problem in the City of Mountain View is under control.

    First, after watching the Frontline program on the “War against the EPA” I feel that the City cannot rely on it to provide sound scientific answers to the current TCE CRISIS. Yes I said CRISIS because it is NOT UNDER CONTROL and NOT BEING CLEANED UP ACTIVELY.

    In fact, I have been proving for months that there is no scientific ambient water or air monitoring of the City of Mountain View by either the EPA or the CARB. And no one in the agencies can explain this in any way given that the location was proven to be hazardous enough to be labeled a “SUPERFUND” location.

    This is intentional because if proof of such hazardous conditions are still present, the land devaluation as a result could bankrupt the City of Mountain View. The land sales or developments would be devalues to such a degree, that if the city has issued any bonds dependent on such revenues, those bonds will default.

    In the research I have done the approach described in this article is still way from being established as a cleanup strategy. In fact, there is NO SCIENTIFIC APPROVAL of this method to be used in such a large scale problem site like those in Mountain View.

    If you read the new article carefully, their EXPERIMENT only employed 800 trees. If this approach was to be used, large areas of Mountain View would need to be leveled regarding land usage and trees would need to replace them. The trees would take as much as 10 years minimum to mature, and who knows how long it will take for the “cleanup” to complete.

    The City of Mountain View seems to be grasping at anything to try to prevent the large scale land devaluation caused by the TCE CRISIS. I hope that more enlighten and educated people will get involved and prevent any deception regarding the public safety of Mountain View.

  13. WARNING LONG BUT NECESSARY TO SUBSTANTIATE MY INFORMATION

    In response to John Freeman you said:”I personally believe you are mistaken on many topics you’ve discussed above.. “

    Whenever I see or hear the phrase “I Personally Believe” my red alert sounds, this is a disclaimer that the following information will not be substantiated be facts, only opinion. Thus it lacks scientific basis or evidence until it has been demonstrated.

    “EPA has clearly offered guidance and approval for hundreds of such projects that have been implemented and were successful Across the Nation more information can be found on their clue-in.org EPA website search tce phytoremediation using poplar.”

    MY famous cut and paste:” 3.2.3 Performance to Date

    THE TREES HAVE BEEN IN THE GROUND FOR LESS THAN ONE GROWING SEASON, SO AS OF NOW THERE IS VERY LITTLE PERFORMANCE DATA AVAILABLE. Some sampling of evapotranspiration gas was conducted by placing Tedlar bags over entire trees. Data from these air samples suggests that the trees are evapotranspirating some VOC’s. However, the VOC concentration in the Tedlar bags matches the background concentrations of VOCs in control samples. This could be due to VOCs volatilizing from the soils, or it could be due to evapotranspirated VOCs that may have gotten into the control samples. Future sampling designs will attempt to determine accurate background VOCs. Additionally, there is some tree growth data for the trees. THEY HAVE GROWN ABOUT 30 INCHES ABOVE GROUND SINCE PLANTING. FIGURES 4 AND 5 ARE PHOTOGRAPHS OF THE TREES AT EDWARD SEARS TAKEN IN JULY 1997 SHOWING THEIR SIZE AFTER ABOUT 7 MONTHS OF GROWING ON SITE. SITE MANAGERS PLAN TO SACRIFICE ONE TREE EITHER AFTER OR DURING THE NEXT GROWING SEASON TO DETERMINE THE EXTENT OF ROOT GROWTH.( https://clu-in.org/products/intern/phytotce.htm)

    So this study indicates it cannot validate ANY PERFORMANCE FOR FUTURE USE.

    “The ability to integrate these trees into neighborhoods and local businesses is key! large-scale swaths of land do not need to be cleared… rather trees can be interplanted with existing structures quite easily because they use groundwater little or no irrigation is required after 2 years and the trees seem to reach large enough height size to be effective within 4 to 5 years. this is a long-term solution that can be integrated by the public. poplar trees can live up to 50 years.”

    As far as I said, this process will not clean up the TCE CRISIS for many years, if your only going to use interplanted trees, this will only GREATLY reduce the actual cleaning up done by the trees. Given that we have as much as many TONS of the pollutant, you are making painting a very rosy picture on a process that could take MANY years to succeed. What about the current monitoring? I still have found no continous monitoring of these cites especially regarding ambient air in situ continual monitoring. The last study published by the EPA indicated only 3 samples per year at 8 hours, in vitro using a container known to interact with the chemical TCE.

    “And if they are in the way of future development they are cut off while dormant in winter and easily replanted at which time they root in the spring and re-establish themselves seeking groundwater with new taproots immediately. There are many Legacy sites that are undeveloped that could also use this technology and as a PHYTO BARRIER retarding and removing the movement of plumes towards Office Buildings and the bay this technology should be clearly adopted. In my professional opinion.”

    As far as the report you discuss, there was no evidence that this process creates a “PHYTO BARRIER”. In fact the more dispersed the trees planted are the less effective such a “PHYTO BARRIER” will be. Also the trees are limited in their ability to absorb the TCE based on the limits of their roots, so measuremnts mae the study indicated it had a starting statistic at Carswell of 610 ug/L on Dec 1996, 570 ug/L in May 1997 and 550 ug/L in July 1997. But at the same time cis-DCE increased of 130 ug/L on Dec 1996, 140 ug/L in May 1997 and 170 ug/L in July 1997. And any absorbed TCE was evaporated into the air in this portion of the report:

    “Some analytical work has been done on the tree tissues at the site, but this type of information is still in the early stages of collection. Data from November of 1996 indicated a TCE signature in the whips that were planted over an area where the groundwater was the shallowest. This indicates that the young trees were capable of EVAPOTRANSPIRATING TCE after just one growing season. Now that the trees have been on site for more than an entire growing season, site managers at Carswell plan to increase monitoring at the site to include a whole suite of water, soil, air, and tree tissue sample analysis. Some of the more unique data they plan to collect (in relation to the other case study sites) are analyses of microbial populations and assays of TCE degrading enzymes in the trees.”(same study)

    In fact this study did not monitor the ambient air quality, the lack of humidity in Mountain View will increase the of EVAPOTRANSPIRING of TCE based on the text from that study:

    “3.3.3 Performance to Date

    Evapotranspiration rates at Carswell for May 13 and 15 and June 10, 11, and 12 of 1997 have been determined. Unfortunately, no quantitative evapotranspiration data was available to include in this report. Qualitatively, both types of trees were capable of EVAPOTRANSPIRING TCE, and the 5-gallon trees are EVAPOTRANSPIRING more water than the whips. This was to be expected because of the greater total surface area of the 5-gallon trees’ leaves. In addition, the transpiration rates were generally higher in June than May, which is likely due to a combination of warmer weather and more fully developed leaves. There also appeared to be a midday decline in transpiration during June, indicating that the plants were experiencing water stress during the hottest part of the day in the summer months. In other words, the water demand for the tree exceeded the supply during that time. There was also a notable difference in transpiration rates between days in June, with cloudier days resulting in lower transpiration rates. In addition to evapotranspiration information, some tree growth data has also been collected. In 16 months the whips have grown about 20 feet, and the 5 gallon bucket trees have grown faster than the whips.

    Groundwater samples were collected from the 29 monitoring wells and analyzed on three occasions to date. Concentrations of TCE, cis-DCE, and trans-DCE, and vinyl chloride were determined from these samples. They ranged from 2 to 930 ug/L TCE in the groundwater, with most samples falling in the 500-600 ug/L range. Average concentrations of the contaminants on the three sampling dates are provided in Table 20, with the exception of vinyl chloride. Vinyl chloride was only detectable in a handful of samples and generally in low levels, so an average concentration was not determined.”(same study you cited)

    You finally said “ And if they are in the way of future development they are cut off while dormant in winter and easily replanted at which time they root in the spring and re-establish themselves seeking groundwater with new taproots immediately. There are many Legacy sites that are undeveloped that could also use this technology and as a phyto barrier retarding and removing the movement of plumes towards Office Buildings and the bay this technology should be clearly adopted. IN MY PROFESSIONAL OPINION.”

    Again the use of “IN MY PROFESSIONAL OPINION.” Raises my red alert. First aren’t you just a plant physiologist? Are you in any way trained in the science of toxic pollution? Granted I only have an associates degree in Life Sciences, but I have had 10+ years’ experience in the Toxic chemical control and detection industry working for Pollution Research and Control Corp and Dasibi Environmental Corp. I feel the citizens of Mountain View NEED a proven SCEINCE to solve the TCE CRISIS. And especially given that this report was written in 1998 and no other report is being used to prove validity by the results being replicated with similar results.

    I simply state that too many people are painting the most OPTIMISTIC picture to prevent the economic losses that are going to occur when the lack of action is proven to result in just a lot more problems in the future

  14. In response to John Freeman you said:”the endophytic bacteria HELP TO DEGRADE THE TCE DOWN to chloride internally. Reducing risk associated with such VOC. the EPA stated in Report the soil has a better transpiration of vocs, than poplar trees, which is negligible at best. While the trees are not perfect for all Sites they do help compliment some of the existing countermeasures that are already in place.”

    It appears you are in fact not claiming my information is false or misleading. Thank you. I try to be fair, and I also try not to misinform anyone as much as possible.

    You simply still do not address that fact the trees do not appear to break down the majority of the TCE, it simply is evaporated by the tree to remove it from the ground water. The study in fact declares this to be true. You cannot in fact prove that the trees are as effective to remove TCE in ground water or soil as effectively as simply removing it by digging it up and replacing it with clean soil.

    What you are going to get is higher levels of ambient TCE in the air because your tree are designed to prevent TCE from being NOT absorbed through the roots. Your process has not been proven to break down TCE within the tree itself alone, until you do so, it is “not production ready”. In my background the EPA has 3 “Phases” for research and development purposes they are described as:

    Phase 1: feasibility study

    Phase 2: prototyping and manufacturing study

    Phase 3: market ready.

    This idea seems to not yet achieve the scientific standard of phase 1, let alone phase 3 which would require a declaration of scientific certainty and safety.

    Also, what kind of long term unintended consequences regarding the local biosphere isn’t even taken into account. What if the local life in consuming the parts of the trees in fact produce a new poisonous protein because of the genetic manipulation of this tree? What larger problem could result? Does anyone event take into account the “butterfly-effect”. Can the EPA even understand the long term possibilities and insure that they will not happen?

    AS an already declared problem, the City already has enough of a TCE vapor problem that all new buildings are designed to prevent vapor intrusion, and what your suggesting is putting out the fire with gasoline.

    What I find very questionable is the use of this news resource to “market” the GMO Poplar trees developed by you in the first place, if you read this citation:

    “The darker, taller poplar trees shown at the test site at the end of their third season were inoculated with microbes, while the shorter, lighter-green trees (center row) were not given the bacteria.John Freeman/Intrinsyx Technologies Corporation””( http://www.washington.edu/news/2017/08/14/probiotics-help-poplar-trees-clean-up-toxins-in-superfund-sites/)

    This story appears to be the manipulation of the news to act as an advertisement of a product you developed, for use in a process that has not been proven safe, that could in fact be very harmful to those who live in Mountain View.

    I think the public must be informed of the relevant facts before being marketed any “Cheap fix” that could be more damaging then the problem.

  15. In response to John Freeman you said: “Clearly you did not understand the science behind this and there’s no point in arguing all of these points that are completely manufactured . you have no understanding of the system or the science whatsoever. GENETIC MANIPULATION WHAT GENETIC MANIPULATION? this is a native bacterial endophyte that naturally lives inside the tree it is not a GMO. “

    OF COURSE MY FIRST QUESTION IS, ARE YOU INCREASING THE BACTERIAL ENDOPHYTE ABOVE IT’S NATURAL LEVELS? ARE YOU IN FACT MANIPULATING THE NORMAL LEVELS IN ANY WAY? I will concede that it may not be “Genetic Manipulation” as it is generally accepted as :

    “Genetic engineering, ALSO CALLED GENETIC MODIFICATION, is the direct manipulation of an organism’s genome using biotechnology. It is a set of technologies used to change the genetic makeup of cells, INCLUDING THE TRANSFER OF GENES WITHIN and across species boundaries to produce improved or novel organisms.”https://en.wikipedia.org/wiki/Genetic_engineering

    But it does sound like you’re doing UNNATURAL SELECTION at the very least, your CROSS-BREEDING DIFFERENT PARTS OF DIFFERENT SPECIES OF TREES TO CREATE A HYBRID. That may not be genetic manipulation in the sense that you are not introducing a gene of an entirely different species into your target. But your result is still a new species, just not made by genetic modification per se. And even making a hybrid in this process can satisfy the above definition because it states “INCLUDING THE TRANSFER OF GENES WITHIN” as a part of the definition. Even if you didn’t manipulate the genetic code, and manipulation of the original breed of tree would result in the classification of your work as “Genetic Engineering”

    This is still a HUMAN MANUFACTURED PRODUCT, almost certainly you have PATENTED IT AS WELL as the technique so as to ensure your group can profit from it.

    And you still haven’t addressed whether the cost of actual cleanup is GREATER THAN the use of your trees. The bottom line is that you cannot yet ACTUALLY AMORTIZE THE COSTS AT ALL. Does your knowledge base determine your products costs via an established protocol of the use of your approach? Can you proven an established cost methodology? If you can’t than you cannot make any VALID cost comparison.

    To me any “UNPROVEN” method should be one of last resort. Because the consequences are “UNKNOWN”.

  16. ANOTHER LONG ONE PLEASE READ?

    In response to John Freeman you stated: “Understanding TCE volatilization rates in poplar trees is critical for this technology to gain widespread acceptance amongst hazardous waste site managers and regulators. There may be concern if the trees are transpiring high concentrations of TCE into the atmosphere, where the pollutant becomes an air quality concern. Proponents of phytoremediation argue that VOCs will volatilize from the groundwater, through the soil, and into the air in the absence of trees. For example, plants will invade sites that are left unattended for extended periods of time, and invasive plants may evapotranspirate the contaminant. That being the case, there would be some evapotranspiration in the absence of a treatment strategy. Phytoremediation schemes would only accelerate the process of volatilization that occurs naturally. Still, volatilization concentrations are decreased by a number of factors, such as exclusion of nonpolar compounds at the roots. According to Davis et al. (1996), “Very few contaminants are sufficiently water soluble, non-toxic to plants, and volatile enough to reach atmospheric concentrations that would be of concern by [evapotranspiration].”

    If you read the article I quote:

    “Several years ago, Doty and her colleagues discovered SYMBIOTIC BACTERIA IN A HYBRID POPLAR (Populus deltoides crossed with Populus nigra) that completely break down TCE into chloride ions and carbon dioxide (Appl. Environ. Microbiol. 2012, DOI: 10.1128/AEM.06852-11). THE RESEARCHERS FOUND THAT THEY COULD SUCCESSFULLY INOCULATE OTHER POPLAR TREES WITH THE BACTERIA, A STRAIN OF ENTEROBACTER, BY SOAKING TREE CUTTINGS IN A SOLUTION CONTAINING THE MICROBE. THE MICROBES COLONIZE THE PLANTS AFTER ABOUT A WEEK BY ENTERING THROUGH THE ROOTS”( https://cen.acs.org/articles/95/web/2017/09/Trees-probiotic-boost-clean-up-a-carcinogen.html)

    This is an engineered species of tree given that the living result is NOT NATURAL. Also this process may not last the lifetime of the tree given that TCE can and does kill the microbes over time. I have not seen any studies that indicates the persistence of the microbes over a lifetime of the tree. THUS WE DO NOT HAVE ANY SCIENTIFIC CERTAINTY OF THIS TREE WILL WORK OVER MORE THAN 3 YEARS.

    This would also appear to substantiate my concerns Given that the reports indicate that these tree will pump 50+ gallons a day according to the report called “PHYTOREMEDIATION OF CONTAMINATED GROUNDWATER USING POPULUS TREES” by Erika Szonntag issued on 14 November 2012 (http://rydberg.biology.colostate.edu/phytoremediation/2012/Remediation%20of%20groundwater%20with%20poplar%20by%20Erica%20Szonntag.pdf).

    At that rate of fluid flow, the BACTERIAL ENDOPHYTE you describe will need to consume or degrade as much as 110 micrograms/liter. This was a reported measure found in the report titled “Mountain View, California’s Mystery TCE Hotspots” By Lenny Siegel November 18, 2013 found here (http://www.cpeo.org/brownfields/reports/I-M/MVHotspots.pdf)

    First you need to convert that to gallons given the measurement standard, which 1 gallon is 3.78 liters, so that 110 timed 3.78 is equal to which is equal to 415.8 micrograms per gallon. If said bacteria cannot process 50 times 415.8 micrograms or 20.79 grams of TCE in a day, the unprocessed TCE absorbed is vaporized by the trees.

    There is in fact from what I can see no measurement of the rate of TCE breakdown by a poplar trees with the BACTERIAL ENDOPHYTE. Until you can measure the rate of breakdown of the TCE by the microbes, you aren’t cleaning up anything. And in fact the study text you provided proves this fact by saying “There may be concern if the trees are transpiring high concentrations of TCE into the atmosphere, where the pollutant becomes an air quality concern.”

    Even though it followed up by stating “Proponents of phytoremediation argue that VOCs will volatilize from the groundwater, through the soil, and into the air in the absence of trees. For example, plants will invade sites that are left unattended for extended periods of time, and invasive plants may EVAPOTRANSPIRATE THE CONTAMINANT. That being the case, there would be some evapotranspiration in the absence of a treatment strategy. PHYTOREMEDIATION SCHEMES WOULD ONLY ACCELERATE THE PROCESS OF VOLATILIZATION THAT OCCURS NATURALLY. Still, volatilization concentrations are decreased by a number of factors, such as exclusion of nonpolar compounds at the roots. According to Davis et al.”, this does not take into account the increased rates that will occur based on the 50 gallon/day process.

    What nonpolar compounds will reduce the vaporization? Will this in fact also reduce the effectiveness of the TCE cleaning process, most likely yes? Because the roots being semi-permeable membranes are only able to either prevent molecules from crossing them based on size, or they cannot prevent it at all. H2O being a very small molecule can pass easily along with many simple nutrients the trees need, where TCE is a very large one.

    If your hoping to accelerate the TCE removal, you’re not able to restrict its absorption by the trees. And since the trees absorb at the 50 Gallons per day rate, this is clearly an accelerated process. The TCE vaporization is more controllable by other means of TCE removal, via real removal of the contaminated soil. You proposal poses more of a risk than people are lead to believe.

    You’re simply vaporizing the TCE through the tree at a rate of 20.8 grams a day per tree. But since it is a very heavy molecule, it will not disperse in the atmosphere without significant wind. It will just settle in a layer from 5 to 10 meters in altitude in the area where the trees are. You may be removing it from the ground water and soil, but in the process you’re aerating it into the atmosphere. Thus you are making it actually TCE pollution more dangerous and impossible to control in a gaseous state and not solid or liquid.

  17. In response to John Freeman you said:”Assuming that the undegraded tce is automatically being volatilized by the tree is the flaw in your logic.”

    Your assumption that it is TCE vaporization not accelerated is yours. I need to can see a scientific experiment where a control and an experimental lot is continually monitored for any increase in TCE vaporization. And such significant research dose in fact prove it does not happen, I simply raise a valid scientific question. It appears you are making an assumption the TCE vaporization is not accelerating, I simply state there is not proof it is not occurring.

    You said;” EPA Report states a large amount TCE sticks inside tree to cell walls and is not volatilized. Then there is the other many different native species of bacteria also in the tree with lesser TCE degradative rates in addition to the selected native non-GMO endophyte.”

    I have only made an argument that in the most liberal sense, your organism is “manipulated” and “deviates” from natural homeostatic levels. That your approach cannot be assumed to be permanent, unless you are going to continuously feed the microbes to the trees. The fact is that TCE is toxic and will kill the trees eventually. So as a long tem approach, there are problems with it. You using the trees in a manner that you cannot predict the outcomes greater than 3 years.

    You stated: “ Taken together with the 500 mg/kg increase in the soil chloride Associated rhizosphere adjacent inoculated tree roots this means vast majority TCE being degraded internally to chloride and exuded through root efflux proteins into soil where becomes table salt NaCl. “

    Again, until I can see some research performed in the Mountain View waste sites, where a control and experimental group demonstrates that you assumption is correct, I express a valid scientific question. The fact is you have not scientifically determined the rate of TCE breakdown performed by the process you described. Nor at the rate necessary to prevent aeration of the TCE in the process.

    I also propose that if this was such a “miraculous” process, why is there so little funding spent on this research? It appears to be almost “orphan” science, only about 1 report a year is discussed on the internet. The internet is NOT PEER REVIEWED. So this means you need to find “scientific publications” to determine its scientific validity.

    TCE Phytoremediation research is appearing to be published through many media sources, but not sources like “The Journal of Bioremediation & Biodegradation” , “The Journal of Environmental & Analytical Toxicology” or “The Journal of Pollution Effects & Control” Until you can provide such “peer reviewed” and “scientifically validated” reports, I feel safe to reject what is “unproven” as a “valid approach to TCE control.

    I find that the internet has become a very dangerous place where the old “snake oil” salesman mentality can thrive. I will not base my safety on sources that are not published in scientific journals in any way, because those publications scientifically assess the validity of the research before publication. My father, Dr. Jack Goldstein, the “father” of spectrophotometry in the US, socialized me into understanding how people can use science deceptively.

    You stated: “Furthermore to EPA point TCE already going into air due to soil and water volatilization rates inherent on these TCE contaminated sites.”

    Until you can in fact prove this process DOES NOT ACCELERATE TCE VAPORIZATION via a control and experimental group in Mountain View, I simply can only state you have no proof that it is a safe approach.

    You will need to isolate groups of the trees and place them in their own biosphere emulating the City of Mountain View conditions, but one being with only a controlled rate of TCE introduction being feed into the trees, and one where the soil perfectly simulates the City of Mountain View conditions. Then TCE vaporization measurements need to be made to determine if the City of Mountain View is in fact making the TCE problem worse by using the trees.

  18. John Freeman:

    Just a follow up:

    My fathers work resulted in the following patent found here: http://www.google.com.pg/patents/US3520614

    Also if you look at this report found here (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0ahUKEwiTqoPij4bXAhUF4mMKHRc_Bn8QFghQMAg&url=http%3A%2F%2Fdrum.lib.umd.edu%2Fbitstream%2F1903%2F10227%2F1%2FCastellanos_umd_0117E_11040.pdf&usg=AOvVaw2wJWO0j37SawiRhJPRm6M_)

    My father’s scientific equipment and procedures were used in this dissertation; it also indicates that Santa Clara County is not in compliance with the National Ambient Air Quality Standards set by the EPA as of June 2009.

    The list of pollutants in this report includes CO, NOX, SO2, VOC, NH3 Particulate Matter 10 Microns, and Particulate Matter 2.5 Microns.

    This report indicates also that the meteorological events in the Santa Clara County are not mitigating the air quality. It appears to have the opposite effect.

    Given that this report already indicates that the air quality is already not up to EPA standards in Mountain View involving these toxins, I can only imagine what it is like on ones not being properly monitored by either the EPA or the CARB. In fact the EPA and the CARB has no record of continuing or continuous ambient air quality in Mountain View involving the chemical TCE at all.

    When we decide to in fact increase vaporization of TCE in any significant way there are going to be major consequences. It is already known to be hazardous enough to require active vapor intrusion protection in new buildings in Mountain View, This means the local atmosphere is toxic enough to require this active remediation. The public safety is only going to be made worse even if only a small increase in TCE vapors occurs due to this proposed process.

  19. Dear Sir, Thank you for your comments and concerns. It is useful to get inputs from all perspectives. We are confident in our approach and pleased with the resulting data to date. We look forward to the success of our work and would hope that with time you too might come to appreciate that success.

  20. In response to John Freeman: you stated: “Dear Sir, Thank you for your comments and concerns. It is useful to get inputs from all perspectives. WE ARE CONFIDENT IN OUR APPROACH AND PLEASED WITH THE RESULTING DATA TO DATE. WE LOOK FORWARD TO THE SUCCESS OF OUR WORK AND WOULD HOPE THAT WITH TIME YOU TOO MIGHT COME TO APPRECIATE THAT SUCCESS.”

    My only response can be until you can in fact provide any research that has been published in “The Journal of Bioremediation & Biodegradation” , “The Journal of Environmental & Analytical Toxicology” or “The Journal of Pollution Effects & Control”. All you have is “faith” or an “opinion” that your approach is scientifically sound.

    To me your data, since it has not been certified or “peer reviewed” as sound is simply very incomplete. Again, I cannot agree to your premise that your approach is going to solve any problems in Mountain View. Before we move forward, we must have a lot more scientific proof. Otherwise, it will be a waste of money, time, and possibly cause much more problems in the long run.

    I have eye-witnessed many situations where instead of simply cleaning up the pollution, many experimental approaches were used because they were “cheaper”, and “easier”. But they wound up simply not working, for example the Cape Cod Otis Site (http://www.capecodtimes.com/article/20110522/news/105220322) . Until a commitment is made to solve the problem by truly “cleaning-up” the Mountain View TCE problem, it will be a perpetual problem that will never be corrected.

    Do we want to live in a toxic location, or do we want to really “solve” the problem? It is our time to choose and commit to solving the problem.

  22. In response to john freeman you stated:

    “Namely that this peer reviewed published scientific research project was located on the MEW site in Mountain view CA. See link to one of the best Environmental Journals ES&T and our findings(https://www.ncbi.nlm.nih.gov/pubmed/28737929) ”

    I acknowledge your report, however it does not state that it is safe regarding increased vaporization of TCE, the abstract stated:

    “The combination of native pollutant-degrading endophytic bacteria and fast-growing poplar tree systems offers a readily deployable, cost-effective approach for the degradation of TCE, and MAY HELP MITIGATE potential transfer up the food chain, VOLATILIZATION TO THE ATMOSPHERE, as well as direct phytotoxic impacts to plants used in this type of phytoremediation. “

    Your study simply does not establish that you have proven it as a viable solution. Just like all other studies I have seen, they do not in fact conclude that this approach is a scientifically acceptable one yet. All you are doing is trying to convince those who do not understand the details of your solution. I simply keep on asking you to provide PROOF that it does HELP MITIGATE the VOLITIZATION TO THE ATMOSPHERE.

    Even if the report is accurate that the trees are metabolizing TCE the passage below indicates more serious questions:

    “The inoculated trees excreted 50% MORE CHLORIDE ION INTO THE RHIZOSPHERE, indicative of INCREASED TCE METABOLISM IN PLANTA. Data from tree core analysis of the tree tissues provided further supporting evidence of the enhanced rate of degradation of the chlorinated solvents in the inoculated trees.”

    That means that as much as 50% of the original TCE can be volatized into the atmosphere that the tree absorbs. The simple truth is that you have no measurements regarding the acceleration of TCE volatilization using your method. When you have such data, I would be very confident in your work and support its application in the City of Mountain View. But you simply do not have this data. You need to perform a study to determine if TCE volatilization increases due to the function of these trees. Can’t you understand this? I just keep on reminding you that your work is incomplete and creates more questions that need to be answered.

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