An idea that may be too removed from the general field of expertise here. For those who live in suburbs (and have gardens/front yards/...), look at your weeds. Some of them, like Conyza canadensis (incidentally, a very aggressive alien in Europe), may hyperaccumulate certain substances (in this particular case, Hg, Pb, As and some other things you don’t want in your food beyond micro levels). If you leave them to grow until just fruiting and then take out with roots, you will reduce pollution there (and the aliens’ spread). However, you will need to put them somewhere, which may be inconvenient.
While technically true, will it make any difference? How much heavy metals (e.g. in mcg) would one plant accumulate? How many plants will it take to reduce the heavy metal pollution of a patch of ground by, say, half?
There are too many qualificators to go into detail here. You might wish to choose a plant that takes out more of a specific pollutant, or of several. Here are some references for Conyza canadensis specifically, they will give you the general idea why people are interested in this on industrial scale.
Potential of weed species applied to remediation of soils contaminated with heavy metals. J Environ Sci (China). 2004;16(5):868-73.
Potential hyperaccumulation of Pb, Zn, Cu and Cd in endurant plants distributed in an old smeltery, northeast China. Environ Geol (2007) 51:1043-1048.
Heavy Metal Accumulation in Plants on Mn Mine Tailings. Pedosphere (2006) 16:1, 131–136.
Identification of a Cd accumulator Conyza canadensis. J Hazard Mater. 2009 Apr 15;163(1):32-35.
Phytoremediation is a developed field, with many plants being screened for efficiency. I would begin with learning what species you do have, and then googling them. (Maybe if you write to some guy who studies something that you have, you can offer him joint research—you gather hay and soil at your place, he analyses them for HM (so you save money). If you have a background in statistics, it raises your chances to Eucalyptus height from about clubmoss height:)
As to ANY difference at all…
The more biomass the plant gains, the more overall quantities of accumulated substances will be taken out (meaning if you weed it out earlier, that will be less effective). Also, if you only mow your lawn, you leave roots in soil, and they will probably contain the highest amounts of heavy metals (and some plants can re-grow later, possibly reaching higher than average concentrations of pollutants). And the part that you have cut off will fly away and add to the general level of pollution. However, if you don’t mow your lawn, it might look less tidy:)) there will be status repercussions:))
If the plant is a serious weed, it would likely produce thousands of easily dispersing seeds per specimen (so you shouldn’t worry about it NOT appearing again). If there is a wetland in your area, sedimentation processes and typically clonal nature of surrounding vegetation (reeds) will make heavy metals accumulate there (wetlands are sinks), so it is a good thing to take them out from surrounding soil in the form of fast-growing, short-lived biomass. In some (usually rural) areas grass is yearly burned, which would release a significant amount of the collected pollutants into the air (and that is not good).
(And of course, trees will gather pollutants from air more than, say, cabbage does, so if there is any significant effect it should be for vegetables and not fruit.)
So I think there is little to gain from not doing it and at least some good gained from doing it.
(Still haven’t found the time to check the literature for the best plant to remove HM, but I remember about it.)
I really can’t yet estimate losses/gains in money units; perhapsit could be organized as a community event of promoting neighbouriness. Neighbourhood?
It seems to me like you are more interested in signaling concern about cleaning up heavy metals than actually cleaning them up. Do you agree with that assessment?
I am even more interested in free advice on statistics of soil science, given to an internet user, because I do happen to be a member of a NGO and so have to signal concern more often than I honestly feel it. (After a while concern dwindles, but annoyance grows.) I would not want to signal concern about yet another problem without due preparation in real life.
Phytoremediation is a developed field, with many plants being screened for efficiency.
Does anyone actually do this in real life (as opposed to writing academic papers about it)?
So I think there is little to gain from not doing it and at least some good gained from doing it.
I notice the lack of numbers :-)
If you do have a heavy metals soil pollution problem, do you think bioaccumulating weeds will significantly help? If you do not, why should you bother? Talking about lawns, no one eats that grass, so you can make the argument that it’s better to have contaminants tied up in the soil rather then extracted.
I don’t know if people do this in real life (or I would have chosen a different thread), but one obstacle why they would not is lack of infrastructure. Once you get a truckload of toxic waste, what to do with it?.. Also, I hope to have some numbers for one species (actually, for a fraction of its ecoforms) in a limited range of pollutants in a specific geographic area, under specific land use conditions, collaborating with chemists who will hopefully find the problem interesting enough, AND I live in Ukraine. I won’t have time for it until after defending my thesis. Give me a Latin name, and I will try to come with a prediction, however off key; but generalizing across orders of flowering plants is simply wrong.
(ETA: a nitpick. A lawn is not a HM sink. The soil is far too often disturbed, and new layers are not yearly deposited there. It won’t hold the pollutants reliably. Maybe, under some conditions, it is better not to extract them, I will have to think upon it. And the concept of a grass that nobody ever eats blew my mind, it did. Save yourself, man! (Woman, child, alien, AI.) Run! Sell your house to a sci-fi writer and don’t look back!)
(Still haven’t got to read stuff on that, maybe I’ll be more lucky next week. After five minutes by the clock thinking about the idea and its alternatives, have two results: 1) I think veeery slowly, 2) maybe it’s possible to make a thin porous cable stuffed with enzyme analogue to download HM directly from the soil, collect them on electrodes once they are in, and extract massively in a special facility.)
An idea that may be too removed from the general field of expertise here. For those who live in suburbs (and have gardens/front yards/...), look at your weeds. Some of them, like Conyza canadensis (incidentally, a very aggressive alien in Europe), may hyperaccumulate certain substances (in this particular case, Hg, Pb, As and some other things you don’t want in your food beyond micro levels). If you leave them to grow until just fruiting and then take out with roots, you will reduce pollution there (and the aliens’ spread). However, you will need to put them somewhere, which may be inconvenient.
While technically true, will it make any difference? How much heavy metals (e.g. in mcg) would one plant accumulate? How many plants will it take to reduce the heavy metal pollution of a patch of ground by, say, half?
There are too many qualificators to go into detail here. You might wish to choose a plant that takes out more of a specific pollutant, or of several. Here are some references for Conyza canadensis specifically, they will give you the general idea why people are interested in this on industrial scale.
http://www.b-paper.com/tag/conyza-canadensis (if this seems to you understandable and not too boring, read the following articles for experimental set-ups)
Potential of weed species applied to remediation of soils contaminated with heavy metals. J Environ Sci (China). 2004;16(5):868-73.
Potential hyperaccumulation of Pb, Zn, Cu and Cd in endurant plants distributed in an old smeltery, northeast China. Environ Geol (2007) 51:1043-1048.
Heavy Metal Accumulation in Plants on Mn Mine Tailings. Pedosphere (2006) 16:1, 131–136.
Identification of a Cd accumulator Conyza canadensis. J Hazard Mater. 2009 Apr 15;163(1):32-35.
Phytoremediation is a developed field, with many plants being screened for efficiency. I would begin with learning what species you do have, and then googling them. (Maybe if you write to some guy who studies something that you have, you can offer him joint research—you gather hay and soil at your place, he analyses them for HM (so you save money). If you have a background in statistics, it raises your chances to Eucalyptus height from about clubmoss height:)
As to ANY difference at all…
The more biomass the plant gains, the more overall quantities of accumulated substances will be taken out (meaning if you weed it out earlier, that will be less effective). Also, if you only mow your lawn, you leave roots in soil, and they will probably contain the highest amounts of heavy metals (and some plants can re-grow later, possibly reaching higher than average concentrations of pollutants). And the part that you have cut off will fly away and add to the general level of pollution. However, if you don’t mow your lawn, it might look less tidy:)) there will be status repercussions:))
If the plant is a serious weed, it would likely produce thousands of easily dispersing seeds per specimen (so you shouldn’t worry about it NOT appearing again). If there is a wetland in your area, sedimentation processes and typically clonal nature of surrounding vegetation (reeds) will make heavy metals accumulate there (wetlands are sinks), so it is a good thing to take them out from surrounding soil in the form of fast-growing, short-lived biomass. In some (usually rural) areas grass is yearly burned, which would release a significant amount of the collected pollutants into the air (and that is not good).
(And of course, trees will gather pollutants from air more than, say, cabbage does, so if there is any significant effect it should be for vegetables and not fruit.)
So I think there is little to gain from not doing it and at least some good gained from doing it.
There are opportunity costs. It costs time and maybe money for procuring the plant.
(Still haven’t found the time to check the literature for the best plant to remove HM, but I remember about it.) I really can’t yet estimate losses/gains in money units; perhapsit could be organized as a community event of promoting neighbouriness. Neighbourhood?
It seems to me like you are more interested in signaling concern about cleaning up heavy metals than actually cleaning them up. Do you agree with that assessment?
I am even more interested in free advice on statistics of soil science, given to an internet user, because I do happen to be a member of a NGO and so have to signal concern more often than I honestly feel it. (After a while concern dwindles, but annoyance grows.) I would not want to signal concern about yet another problem without due preparation in real life.
Does anyone actually do this in real life (as opposed to writing academic papers about it)?
I notice the lack of numbers :-)
If you do have a heavy metals soil pollution problem, do you think bioaccumulating weeds will significantly help? If you do not, why should you bother? Talking about lawns, no one eats that grass, so you can make the argument that it’s better to have contaminants tied up in the soil rather then extracted.
I don’t know if people do this in real life (or I would have chosen a different thread), but one obstacle why they would not is lack of infrastructure. Once you get a truckload of toxic waste, what to do with it?.. Also, I hope to have some numbers for one species (actually, for a fraction of its ecoforms) in a limited range of pollutants in a specific geographic area, under specific land use conditions, collaborating with chemists who will hopefully find the problem interesting enough, AND I live in Ukraine. I won’t have time for it until after defending my thesis. Give me a Latin name, and I will try to come with a prediction, however off key; but generalizing across orders of flowering plants is simply wrong. (ETA: a nitpick. A lawn is not a HM sink. The soil is far too often disturbed, and new layers are not yearly deposited there. It won’t hold the pollutants reliably. Maybe, under some conditions, it is better not to extract them, I will have to think upon it. And the concept of a grass that nobody ever eats blew my mind, it did. Save yourself, man! (Woman, child, alien, AI.) Run! Sell your house to a sci-fi writer and don’t look back!)
I’ll ask a simpler question. What is the best (in terms of heavy-metal concentration as % of biomass) that a flowering plant can do?
(Still haven’t got to read stuff on that, maybe I’ll be more lucky next week. After five minutes by the clock thinking about the idea and its alternatives, have two results: 1) I think veeery slowly, 2) maybe it’s possible to make a thin porous cable stuffed with enzyme analogue to download HM directly from the soil, collect them on electrodes once they are in, and extract massively in a special facility.)
To extract heavy metals from the soil you need a LOT of contact surface. Roots excel at this, cables, not so much.
I know. Still might be more feasible.