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Mycoremediation: fixing contamination with mushrooms  RSS feed

 
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Asphalt shingle disposal - Any mycoremediation potential? I have an isolated cabin with a deteriorated asphalt roof covered in moss and pine needles to dispose of.
 
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P Lyons wrote:Asphalt shingle disposal - Any mycoremediation potential? I have an isolated cabin with a deteriorated asphalt roof covered in moss and pine needles to dispose of.


That's going to be a tough one, but given enough time, yes, fungi can degrade asphalt. I would put it in the same class as creosoted railroad ties, which take decades to decompose. And the fiberglass is never going to decompose, just become little bits of glass in the soil matrix, somewhat akin to diatoms.

What are your other options? Putting the asphalt roofing in a retort and cooking it until it becomes char is another way to return it back to nature. Something you may want to consider if you are cooking a lot of biochar.
 
P Lyons
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Thanks John, I have no retort or plans to start making biochar, so that is not really an option. I just wanted to check if there was a better method of disposal than hauling the old shingles to the landfill.
 
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I had a couple of questions regarding a wildflower garden that I converted from lawn, which was sprayed a few times a year with broadleaf weed herbicide. The first being how much should I be concerned considering that I was able to grow wildflowers in this spot last year, could it really be all that bad. My second question is, if I did inoculate the area with the white rot fungi, like you suggested, while the wildflowers were growing would it be detrimental to them? I know for a fact broadleaf herbicides were used but I am not exactly sure which ones.
 
John Elliott
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Josh Cusack wrote:I had a couple of questions regarding a wildflower garden that I converted from lawn, which was sprayed a few times a year with broadleaf weed herbicide. The first being how much should I be concerned considering that I was able to grow wildflowers in this spot last year, could it really be all that bad. My second question is, if I did inoculate the area with the white rot fungi, like you suggested, while the wildflowers were growing would it be detrimental to them? I know for a fact broadleaf herbicides were used but I am not exactly sure which ones.


If it was sprayed "a few times a year", it must have been a puny herbicide that solarized or decomposed in some other way fairly quickly. This is considered a good feature by the chemical companies; they don't want herbicides to persist on the order of years, because then they won't be selling as much. That's why Seed Saver Suers Inc. likes to hook farmers on multiple applications of their herbicidal brew in one growing season. If you've got good soil fungi, they should have it all cleared out by next spring.

How do you know that you have healthy soil fungi? I look for fungus gnats when I till the soil. I sometimes dig up some quality topsoil and screen it so I have a light covering to put on top of my hugelbeds. When I top them off, it seems like a magnet for fungus gnats -- they show up almost immediately. My hypothesis is that all the hyphae newly exposed to the air gives off quite a smell that attracts the gnats. I know people cuss up a storm about fungus gnats on house plants, but outdoors, where they belong, they seem to indicate that you have some healthy soil fungi.

On the other question, wildflowers are like other plants in that the vast majority of them form mycorrhizal associations with soil fungi. So no, it wouldn't be detrimental to the flowers, but on balance beneficial.
 
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I am really concerned about some of the material in this thread suggesting that mushrooms may make heavy metals less biologically available. I've tried to confirm this and failed.

Uwe Wiedemann wrote:
John Elliott wrote:
I always wonder if mushrooms are so great in sweeping up toxins are they toxic waste after sweeping up? For example they take up a lot of
radiation and it is still not advisable to eat European mushrooms. Or do the mushroom break the heavy metals, radioactive elements and other poisons down?


Elements are called that because they can't be broken down. Some elements we need (N,P,K) and so we look for these in fertilizers and try to keep them cycling in the environment . Others, like heavy metals, can accumulate to problem levels. At that point, if there is a plant or a fungus that bioaccumulates it, that plant or fungus is going to be toxic.



I heard something different from a professor in ecology and a mycological society: It's right that fungi take up heavy metals, but these are bound and not available from passing our digestive tract. Mushrooms contain a lot of indigestible substance, which passes right through. That also means, the radioactive elements, if they are there, pass through (they are heavy metals). The danger with radioactive isotopes is, when they are deposited somewhere in the body. The danger from having a few isotopes passing through is very little compared to a long term exposure. I have collected and eaten mushrooms from the woods every year since Chernobyl and I don't feel any negative effects. I think this fear of mushrooms, 2000 km away from Chernobyl, is and was from the beginning WAY unrealistic.



Now, the degree to which heavy metals may be bioaccumulated by fungi appears to depend largely on conditions. http://www.pjoes.com/pdf/21.1/Pol.J.Environ.Stud.Vol.21.No.1.165-169.pdf

The sources that I'm finding suggest that consumption of mushrooms found in areas of high heavy metal contamination should be restricted, not encouraged. Some of the metals may be in a bound form - others not so much, and I don't want to generalise without expert intervention. https://www.sciencedaily.com/releases/2009/10/091030102151.htm http://link.springer.com/article/10.1007%2Fs10534-009-9230-7

Remember also that just growing mushrooms on land contaminated by heavy metals will not make those heavy metals go away. I have run into this notion, and was surprised I had to spell it out. The mushrooms may, under certain circumstances, accumulate the metals, but you still have to get rid of the things somehow - basically as toxic waste.

What John Elliot writes about individual elements seems accurate. Even when some elements are locked up to become biologically unavailable, many processes can reverse that, including, I might add, the activity of fungal mycelia.

What Uwe Weidemann writes about eating mushrooms is difficult to contradict from his experience. Maybe he's collecting from an area of relatively low contamination. Maybe he got lucky. Maybe he got lucky so far. Maybe the conditions in his woods are such that the mushrooms are not accumulating the radioactive substances. Maybe they have decayed to a point where they are no longer a threat. Maybe they are decaying to a point where the mushrooms can accumulate them and they will become a threat. At 2000 km from Chernobyl he's probably safe by now: many of the lighter radioactive elements decayed quite quickly to a point where they are radioactively inert, while the heavier ones mostly dropped out near Pripyat. The degree of risk attached is going to vary according to individual conditions, and the degree to which that risk fails to pay off is a numbers game, and I would not want to overgeneralise from Uwe's experience.
 
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Neil,
Thank you! Yes, mushrooms growing from any substrate (soil, wood, paper, etc.) that may harbor heavy metals or any other toxic substance should not be eaten! Soil fungi do bind up metals in the soil using various organic acids and other compounds, a complex process that is highly dependent on soil composition (both organic and inorganic). Mushroom-forming fungi also uptake heavy metals into their tissue, where it becomes concentrated. Fungi do not destroy or transmute these elements into another element. This is most important for metals and radioactive isotopes. The mushrooms near Chernobyl and Fukushima may uptake these isotopes, but then the mushroom will be radioactive as it will be emitting the damaging gamma radiation that the elements are emitting.

Stay safe yall!
Peter
 
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Neil Layton wrote:I am really concerned about some of the material in this thread suggesting that mushrooms may make heavy metals less biologically available. I've tried to confirm this and failed.


This is not, what I have said. I've said, that heavy metals in mushrooms are not available from passing through our digestive tract! That should not encourage people to eat mushrooms from highly contaminated soils, since chemical reactions occur rarely at 100%. The higher a contamination, the larger the risk, of course.

Some people tried to prevent basically whole (West) Germany after Chernobyl from drinking milk and eating mushrooms. Some caution might have been appropriate in the weeks after the incident - radiation was measurably higher in some areas of the country - but YEARS after it?

I don't think, there is any danger in our area from eating wild mushrooms, and was since 1987. It's ok to be cautious, but the media hype at that time was largely a Cold War thing.

Uwe
 
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