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Living Machines Conference (fwd)







---------- Text of forwarded message ----------
Date: Thu, 2 Sep 1993 23:50:50 -0400 (EDT)
From: Larry London <london@sunsite.unc.edu>
To: sustag-public@twosocks.ces.ncsu.edu
Subject: Living Machines Conference

Date: Thu,  2 Sep 93 14:58:00 -0400
From: glenn.mcknight@canrem.com (Glenn Mcknight)
Message-Id: <60.869.5225.0N18307E@canrem.com>
Organization: CRS Online  (Toronto, Ontario)
Subject: Living Machines Conference

NOTICE TO MEDIA

The Coalition for a Green Economic Recovery will hold a conference October 1 to
3, l993 to discuss and promote the economic andenvironmental advantages of
living machines.  Living machines are, simplistically, engineered water
ecosystems which use natur
al elements such as sunlight, plants and animals to break down toxins,
concentrate metals and treat organic material in sewage and waste water.
Living machines can be part of clean, simple, economical and environmentally
viable solutions to a number of problems.  They offer less costly alternatives
for municipalities planning to spend billions of taxpayers; dollars on
expansions and new sewage a
nd water treatmen systems.  They do not use chlorine


















Article 11236 (123 more) in rec.gardens:
From: dietz@cs.rochester.edu (Paul Dietz)
ubject: Hyperaccumulators?
Date: Tue, 6 Oct 1992 23:15:20 GMT

I just was reading a bit about some plants that are
"hyperaccumulators": they concentrate normally toxic metals in their
tissue to an amazing extent (for example, plants that grow on soils
derived from ultramafic rocks that concentrate nickel in their leaves
to > 3% of their dry weight).  Are there any plants normally grown in
gardens that are hyperaccumulators?

        Paul F. Dietz
        dietz@cs.rochester.edu

Article 11244 (116 more) in rec.gardens:
From: klier@iscsvax.uni.edu
In article <1992Oct6.231520.20515@cs.rochester.edu>, 
dietz@cs.rochester.edu (Paul Dietz) writes:

> I just was reading a bit about some plants that are
> "hyperaccumulators": they concentrate normally toxic metals in their
> tissue to an amazing extent (for example, plants that grow on soils
> derived from ultramafic rocks that concentrate nickel in their leaves
> to > 3% of their dry weight).  Are there any plants normally grown in
> gardens that are hyperaccumulators?

To the best of my knowledge, no.  Though you will see such things as
lead accumulating in root crops like carrots.

Most of the "ultra accumulators" are things like locoweeds, which
pick up selenium in sulfur-poor soils, and you actually get selinium
containing amino acids and proteins (i.e., the selenium "spares" the
sulfur).

There is a cute S. African plant I've read of called "giftboom" (poison
tree) that does something rather spectacular with fluorine, which I've
now forgotten.  Maybe uses Fl- instead of Cl-?????

Kay Klier  Biology Dept  UNI

Article 11254 (121 more) in rec.gardens:
From: dietz@cs.rochester.edu (Paul Dietz)
Subject: Re: Hyperaccumulators?
Date: Wed, 7 Oct 1992 11:52:31 GMT

In article <1992Oct6.205925.7361@iscsvax.uni.edu> klier@iscsvax.uni.edu writes:

> There is a cute S. African plant I've read of called "giftboom" (poison
> tree) that does something rather spectacular with fluorine, which I've
> now forgotten.  Maybe uses F- instead of Cl-?????

"Gifblaar".  It makes fluoroacetate ion, a potent inhibitor of the
Krebs cycle.  One mouthful of this plant can kill a sheep.  A related
species makes some other fluorinated acids, also toxic.

Interestingly, another member of this genus is a nickel
hyperaccumulator.

        Paul F. Dietz
        dietz@cs.rochester.edu

Article 11287 (153 more) in rec.gardens:
From: emolinar@stake.DaytonOH.NCR.COM (Elizabeth Molinaro)
Subject: Re: Hyperaccumulators?Date: 7 Oct 92 18:29:15 GMT

In article <1992Oct6.205925.7361@iscsvax.uni.edu> klier@iscsvax.uni.edu
writes:
>In article <1992Oct6.231520.20515@cs.rochester.edu>, dietz@cs.rochester.edu
(Paul Dietz) writes:
>> 
>> I just was reading a bit about some plants that are
>> "hyperaccumulators": they concentrate normally toxic metals in their
>> tissue to an amazing extent (for example, plants that grow on soils
>> derived from ultramafic rocks that concentrate nickel in their leaves
>> to > 3% of their dry weight).  Are there any plants normally grown in
>> gardens that are hyperaccumulators?
>
>To the best of my knowledge, no.  Though you will see such things as
>lead accumulating in root crops like carrots.

        I read something about Jimsonweed.
        About a month ago, in the Wall Street Journal, page 1
        Apparently, it hyperaccumulates toxic nuclear (now THAT's
        redundant) wastes...and thrives!!!!

        Elizabeth

From: klier@iscsvax.uni.edu
Subject: re: Hyperaccumulators
Date: 8 Oct 92 18:35:08 -0500

Paul Dietz (with a marvelous memory!) remembered the plant I couldn't--
the one that makes fluoroacetate when grown on soils heavy in fluorine,
and thus becomes toxic to animals.  He also remembered the common name
is "giftblaar", not "giftboom" as I had thought.

Dichapetalum is a BIG genus of 150-200 species of the tropics, particularly
Africa.  It's a member of the family Dichapetalaceae, which may be
related to the Euphorbiaceae, the poinsettia family, according to 
Willis's Dictionary.  Alas, Chiltern Seeds doesn't seem to stock it :-(
------
From:   IN%"dietz@cs.rochester.EDU"  

The genus is Dichapetalum.  The three species to which I referred
are:

        D. cymosum      Makes fluoroacetate
        D. toxicarium   Makes various omega-fluorinated fatty acids
        D. gelonioides  A nickel hyperaccumulator

D. gelonioides doesn't have unusually large amounts of fluorine in
its tissues.  I don't remember if D. toxicarium makes fluoroacetate
as well.
--------
Kay

rec.gardens #10472 
From: A.S. Chamove
Re: Hyperaccumulators
Date: Sun Oct 11 19:47:12 1992
Organization: Massey University, Palmerston North, New Zealand

Does anyone know of a plant (edible to cows and horses) that will
concentrate selenium in selenium-deficient soils?

Arnold Chamove
Massey University Psychology
Palmerston North, New Zealand


1] Re: Hyperaccumulators
Date: Sun Oct 11 20:53:28 1992
Organization: University of Northern Iowa

In article <1992Oct11.234712.18978@massey.ac.nz>, 
A.S.Chamove@massey.ac.nz (A.S. Chamove) writes:
> Does anyone know of a plant (edible to cows and horses) that will
> concentrate selenium in selenium-deficient soil?

Species of _Astragalus_ and _Oxytropis_ are notorious for this in low-
sulfur soils.  Of course, when the horse or steer gets too much
Se from the locoweeds, you see "moonblindness" and other neurological
symptoms.
Kay

rticle 11244 (116 more) in rec.gardens:
From: klier@iscsvax.uni.edu
ubject: Re: Hyperaccumulators?
Date: 6 Oct 92 20:59:25 -0500

In article <1992Oct6.231520.20515@cs.rochester.edu>, dietz@cs.rochester.edu (Pau l Dietz) writes:
> I just was reading a bit about some plants that are
> "hyperaccumulators": they concentrate normally toxic metals in their
> tissue to an amazing extent (for example, plants that grow on soils
> derived from ultramafic rocks that concentrate nickel in their leaves
> to > 3% of their dry weight).  Are there any plants normally grown in
> gardens that are hyperaccumulators?

To the best of my knowledge, no.  Though you will see such things as
lead accumulating in root crops like carrots.

Most of the "ultra accumulators" are things like locoweeds, which
pick up selenium in sulfur-poor soils, and you actually get selinium
containing amino acids and proteins (i.e., the selenium "spares" the
sulfur).

There is a cute S. African plant I've read of called "giftboom" (poison
tree) that does something rather spectacular with fluorine, which I've
now forgotten.  Maybe uses Fl- instead of Cl-?????

Kay Klier  Biology Dept  UNI

Article 11249 (115 more) in rec.gardens:
From: london@SunSite.unc.edu (Larry London)
Subject: Re: Hyperaccumulators?
Date: Wed, 7 Oct 1992 05:06:58 GMT

Datura (Jimson Weed) and cattails are reputed to be hyperaccumulators.

Date: 12 Oct 92 00:53:28 GMT

In article <1992Oct11.234712.18978@massey.ac.nz>, 
A.S.Chamove@massey.ac.nz (A.S. Chamove) writes:
> Does anyone know of a plant (edible to cows and horses) that will
> concentrate selenium in selenium-deficient soil?

Species of _Astragalus_ and _Oxytropis_ are notorious for this in low-
sulfur soils.  Of course, when the horse or steer gets too much
Se from the locoweeds, you see "moonblindness" and other neurological
symptoms.
Kay

Article 471 (7 more) in bionet.plants:
Date: Tue, 20 Oct 1992 15:48:56 EDT
Subject: Re: Heavy Metals and Fruit Trees

cpotter@ncsa.uiuc.edu (Clint Potter) Date: Mon, 19 Oct 1992 19:09:08 GMT
Requested info:
> I am after a information on the effects of heavy metals in the soil on fruit
> trees.
> Are metals like Pb and Cd detrimental to the growth of trees like apples,
> peaches and pears?  Is there any research on tolerable concentrations of
> these elements?  Are these metals likely to migrate to the fruit?  What type
> of soil test should be done?  Is total Pb and total Cd adequate?
> Thank you for any information or references.
> Clint Potter cpotter@ncsa.uiuc.edu

Check a recent review article :

       W. H. O. Ernst et al., 1992.  Metal tolerance in plants.
       Acta Botanica Neerlandica 41:229-248.

If it doesn't provide you with the info you need, it may lead you to other
sources in the literature cited.

Mark Kubiske

From: bj368@cleveland.Freenet.Edu (Mike E. Romano)
Subject: Re: Aquaculture
Date: 20 Oct 1992 09:29:30 GMT

  In reference to Larry London's request for further cites of
publications by New Alchemy and on the subject of 
bioremediation, I have the following from my files:

Solar Aquaculture: perspectives in renewable, resource based
fish production, results for a workshop at Falmouth, Mass.
Sept 28, 1981  supported by the National Science Foundation
New Alchemy Institute.

Bioremediation for marine oil spills.  U.S. Gov Doc.  Office
of Technology Assessment  1991
doc # Y 3.T 22/2:2 B 52.7

Bioremediation of contaminated surface soils by Sims &
Matthews.   EPA  1989    EP 1.23/6:600/9-90/041

National Conference on Bioremediation (1988).  Hazardous
waste treatment by genetically engineered or adapted 
organisms.  Superfund '88.  Silver Springs, MD

Bioremediation of petroleum spills in arctic environments.
Alaska Dept of Transportation  1990

Understanding Bioremediation: a guidebook for citizens.
EPA  1991    doc  EP 1.8:B 52/2

Quick Bibliography Series # 92-47.
Biotechnology and Bioremediation.  National Agricultural
Library   Beltsville MD  1991

Practical environmental bioremediation.  Barry King  
Lewis Publishing   1992.

Article 704 in bionet.plants:
Organization: Penn State University
Date: Fri, 11 Dec 1992 09:03:23 EST
Subject: Re: Heavy metals in plants

I'm out of my field here, but I'm somewhat involved in a study here at Penn
State which might at least be interesting, if not relevant to this budding
'heavy metal' discussion.  About 100 years ago in the Eastern US, the
"cahrcoal-iron" industry was pretty big business.  Travelers through
Pennsylvania can still see the huge, stone iron furnaces in state parks and
the like.  The iron workers would fire the furnaces with charcoal which they
produced themselves from the surrounding forests.  One can walk through the
woods almost anywhere in PA and encounter numerous "charcoal hearths" -
elliptical or circular flat areas about 10 to 12 meters across with very
little or no woody vegetation.  The study was designed to try and pin down
why woody vegetation is virtually excluded from these hearths even after 100
years.  I might add that the surrounding woods were heavily logged during
this period, clearcut on 40 year rotations was common.  Needless to say the
woods are growing quite vigerously, but not the hearths.  Tissue-water
relations of test plants (my field) suggest some form of drought stress.
The soil on these hearths is up to 70% organic matter due to charcoal dust
and fragments.  Can there be some heavy metal residue that may have been
concentrated by stacking 10 cords at a time on these hearths and coaling
them?  Some hearths were used very many times over.

Mark Kubiske                < MEK104@PSUVM.PSU.EDU >
School of Forest Resources
Penn State University

Article 708 (1 more) in bionet.plants:
From: BOTSALT@VM.UOGUELPH.CA (david salt)
Subject: heavy metals a few points
Date: 11 Dec 92 22:14:04 GMT

Well I am pleased with the response to my plea for discussion on the topic
of heavy metals and plants.
The discussion on hyperaccumulators is interesting but it is important to
realise that to my knowledge there is no example of a plant which excludes
metals, all plants appear to accumulate metals to some degree. This is probably
due to the cationic metal being driven across the PM via the membrame potential
-ve inside. In tobacco this metal then appears to be compartmentalised within
the vacuole. Once inside the vacuole Cd is bound to the induced peptide
phytochelatins, therebye reducing the Cd's chemical gradient across the
tonoplast and hence reducing the amount of energy required to keep pumping
Cd inside. In oats Cd is transported across the tonoplast via a Cd/H
antiport (presumably driven in vivo by tghe tonoplast H-ATPase or H-PPiase).
Transport of Cd back out across the PM may also be a possibility.
RE Datura: P. Jackson at Los Alamos has done alot of work on the
biochemistry of Cd resistence on Datura innoxia in tissue culture!
IS CADMIUM REALLY SO BAD!!!!!!
a recent article in Nature suggests not!(344, 658-660, 1990)
It would appear that Cd can substitute for Zn in Zn deficient marine diatoms!
Does this explain the slight growth stimulation physiologist have seen (but
not talked about) in Cd tolerence tests using root elongation?
What is Cd doing in the marine diatom? Is it siting in the active site of
catalase or in Zn-fingers?....Any ideas.

Finally are there any biophysicists out there how can explain to me why
crystaline CdS is an interesting semiconductor because the fission yeast
S. pombe makes particles of it when exposed to Cd (and may be also plants)
and AT&T Bell laboratories are interested (Nature 338, 596-597, 1989).

David Salt
Botsalt@vm.uoguelph.ca

Article 710 in bionet.plants:
From: claird@NeoSoft.com (Cameron Laird)
Subject: Re: A big hello
Date: 11 Dec 92 14:49:21 GMT

In article <1992Dec10.234216.8446@gserv1.dl.ac.uk> london@sunsite.unc.edu (Larry
 London) writes:
>In article <1992Dec10.153700.17634@gserv1.dl.ac.uk> you write:
>>In article <92129225625.MIN-LVLBa00330.bionet-news@uk.ac.daresbury> you wrote:
                        .
Is there anybody out there who is interested in how plants deal with
>>: heavy metals (ie Cd, Cu, Zn etc....yes O.K you know what a heavy metal
>>: is). Perhaps were could have a meaningful dialogue?
>>I worked for a while at Plymouth Polytechnic (UK) during the early 80's
>>when Lane and Martin were working on uptake of heavy metals by potatos
>>and strawberries, but I'm not sure what they published.
                        .
                        .
>Here's a thread on the subject I've saved over the past several months.
>There is additional material contained in a number of posts in
>alt.sustainable.agriculture, which I've archived. These mostly relate to
>the work of John Todd, formerly of the New Alchemy Institute.
A paper by K. C. Jones et al., *Nature*, 356, 137, 1992,
analyzes secular trends in pollution around Rothamsted
by measuring plants' incorporated burdens of different
pollutants.  The authors' principal concerns were with
organics--PCBs, hydrocarbons--but I think their biblio-
graphy touches on metal uptakes.
                        .
-- 
Cameron Laird
claird@Neosoft.com (claird%Neosoft.com@uunet.uu.net)    +1 713 267 7966
claird@litwin.com (claird%litwin.com@uunet.uu.net)      +1 713 996 8546

Article 713 in bionet.plants:
From: ajt@rri.sari.ac.uk (Tony Travis)
Subject: Re: Plant communication/sensing references wanted
Date: 12 Dec 92 23:23:45 GMT

In article <921212201751.MIN-LVICa00330.bionet-news@uk.ac.daresbury> you wrote:
: 
:    The subject about says it all: I'm interested in references to literature
:    which explores the capabilities of the plant world with refer712

Article 712 in bionet.plants:
From: ajt@rri.sari.ac.uk (Tony Travis)
ubject: Re: heavy metals a few points
Date: 12 Dec 92 23:18:36 GMT

In article <921211224901.MIN-LHFCa00330.bionet-news@uk.ac.daresbury> you wrote:
: [...]
: The discussion on hyperaccumulators is interesting but it is important to
: realise that to my knowledge there is no example of a plant which excludes
:metals, all plants appear to accumulate metals to some degree. This is probably
: due to the cationic metal being driven across the PM via the membrame potentia
l
: -ve inside. In tobacco this metal then appears to be compartmentalised within
: [...]

I did some work with benzo-18-crown-6 (a synthetic ionophore) which
demonstrated that accumulation of K+ in the vacuole of stomatal guard
cells was dependent on the permeability of the PM to K+ ions.  The
crown ether is incorporated into the membrane and forms K+ permeable
channels.

The driving force for accumulation of K+ is electrogenic proton
extrusion across the PM/tonoplast.  It seems that accumulation of Cd or
any other cation available would depend on membrane permeability rather
than active transport of the metal itself.

        Tony.
--
Dr. A.J.Travis,                       |  Tony Travis
Rowett Research Institute,            |  JANET: <ajt@uk.ac.sari.rri>
Greenburn Road, Bucksburn,            |  other: <ajt@rri.sari.ac.uk>
Aberdeen, AB2 9SB. UK.                |  phone: 0224-712751

From: donachie@vax.oxford.ac.uk
ubject: Heavy metals
Date: 14 Dec 92 13:13:24 GMT
Organization: Oxford University VAX 6620
 
 On the subject of hyperaccumulators, work in this lab is investigating the
nature of the complexes formed in these plants with organic acids, in order to
determine whether these provide a possible mechanism of tolerance for the
plant.  

  The levels of metal which these plants accumulate can be huge, Sebertia
accuminata, a tree from New Caledonia, has a latex which conatins, on a dry
weight basis, 26 % nickel.  This is the highest recorded concentration in any
living ( :-) ) organism.  

  I think that the act of hyperaccumulation is related to the site at which the
plant can be found.  We are working on Alyssum spp here, and these can be, and
are regularly grown in gardens in Europe.  We have plants which are known to be
hyperaccumulators, and as control plants we are using garden seeds bought from
--MORE--(88%)

a commercial supplier.  We think that they won't hyperaccumulate, if they do
then....

  Just some interesting info to pass on over the dinner table ( :-) )
End of article 721 (of 722)--what next? [npq] Article 723 in bionet.plants:
From: cunninsd@esvax.dnet.dupont.com

Subject: plants, metals and contaminated sites
Date: 15 Dec 92 15:55:43 GMT
Distribution: bionet

       This is my first time on this network, but I heard a
discussion of heavy metals in plants was underway, so I 
thought I'd join in. Here at DuPont we have an active 
research program in using plants toremediate contaminated 
soils. For this effort we  have borrowed a term I first heard
used by Ilya Raskin at Rutgers' and called it 
"Phytoremediation". 

        We define phytoremediation as the use of green plants to
remove, contain, or render harmless an environmental 
contaminant.  This definition applies to all plant-influenced
biological, chemical, and physical processes that aid in site
remediation. Although our particular current research 
emphasis is the remediation of lead-contaminated soils, we 
are interested in most other metals and organics as well.  
Simply described, we propose to farm hazardous waste sites, 
biomine the metal contaminants, and reclaim the metals 
through postharvest processing of the biomass. We consider 
the entire process to have multiple, but interdependent 
components. For the technology to be useful each component 
must be sound technically and economically, and must be 
acceptable from a regulatory perspective. Our efforts in 
phytoremediation of lead-contaminated soils address all of 
these areas. I thought I would venture some general comments
on the area and see what reaction they brought.

        Although metal tolerant plants are relatively common, 
most do not accumulate significant quantities of metal in the
above ground biomass. Our metal-removal goals are ambitious,
paralleling removal rates of plant nutrients such as 
nitrogen, potassium, and calcium.  For plant-based 
decontamination to be sucessful, we must find, breed or 
engineer plants that absorb, translocate and tolerate these
metals. These three processes are separate, distinct and, in
some plants, mutually exclusive.(ie tolerance can be obtained
by lack of translocation etc.) We have found that 
combinations of any two processes in one plant are relatively
easy to find.  All three processes, working efficiently in a 
single plant with sufficient biomass to acheive the necessary 
metal-removal rates, will be more difficult to achieve. 

        The discovery or development of such plants might be 
assumed to be infeasible if it were not for the existence of
the hyperaccumulators that have been mentioned on this 
network. These naturally-occurring plants can be found 
growing on ore outcroppings and have spectacular metal-uptake
capacities. The sap of one tree has been mentioned previously
to have concentrations of Ni in excess of 25% dry weight. 
Alan Baker (Sheffield) lists plants with concentrations in 
excess of 1%  Cu and Co and 3% Zn, Ni, and Mn on a dry weight
basis.  Lead levels, although lower,  have been reported as 
high as 8,200 ppm in these plants. We are looking at these 
hyperaccumulators for potential remediation uses, however, 
due to their low growth habits and small biomass, they would
seem to be agronomically and climatically unsuited for 
phytoremediation of most sites. A breeding program to 
increase biomass and metals content is a long-term, crop-
development strategy that could be undertaken. Molecular 
biology, however, may offer valuable shortcuts !!! - (Check 
with your patent attorney, before you release it as this 
plant can have real and significant value)

        Parallel to our efforts with hyperaccumulators, we have
been exploring lead-contaminated sites for plants that 
accumulate lead. Our goal is to find, manipulate, and extend
the lead-uptake limits of these plants. We have collected and
analyzed many plants from Superfund, mining, and other
industrial sites in search of appropriate germplasm. Of the
plants we have analyzed to date, two plants have shown 
significant abilities to accumulate lead. These are hemp 
dogbane (Apocynum sp.) and common ragweed (Ambrosia sp.). 
Their lead accumulation abilities are considerable, but not 
consistent, however, across soils. Most metals, and lead in 
particular, have numerous forms in the soil, not all of which
are equally available for plant uptake.

        Manipulating the chemistry of the soil to maximize lead
removal requires balancing plant-nutritional requirements for
biomass production with the availiability of lead for uptake
by plants. We have found these to be often competing 
processes. Maximizing lead availability requires a lower pH 
and low solution levels of phosphate and sulfate, which 
directly impacts total plant biomass produced. The plant-
nutritional status of the soil must be continuously balanced
against the lead-availability status to maximize total lead 
removal.

        Pb occurs in all of the physicochemical forms measured
in a sequential extraction of contaminated soils, including
water-soluble, exchangeable, specifically adsorbed, 
carbonate, oxyhydroxide, organic, and other forms.  
Experiments have confirmed, however, that there are wide 
differences between soils in these Pb forms and in the 
ability of plants to pick up the metal in question.

        I would be interested in general comments on the 
approach, names of others working in the area, etc. etc..

Article 727 (2 more) in bionet.plants:
From: dr@ducvax.auburn.edu
Subject: Re: A big hello
Date: Wed, 16 Dec 1992 06:32:56 GMT

In article <1992Dec10.153700.17634@gserv1.dl.ac.uk>, ajt@rri.sari.ac.uk (Tony Tr
avis) writes:
> In article <92129225625.MIN-LVLBa00330.bionet-news@uk.ac.daresbury> you wrote:
> : I am a "virgin" bionet user, this is my first message.
> 
> Hello, David + welcome to bionet.plants!
> 
> : Is there anybody out there who is interested in how plants deal with
> : heavy metals (ie Cd, Cu, Zn etc....yes O.K you know what a heavy metal
> : is). Perhaps were could have a meaningful dialogue?
> Ok, everybody - are you interested in discussing heavy metals??

I'd be interested in such a discussion; my current interest would be
taxonomic in nature.  'Fraid I can't make any contribution to such a
discussion at this time, for convoluted reasons, best alluded to by my 
post, "Request: Recruiting/Luring Biologists to the Nets", in sci.bio 
and bionet.general.  That same post would also serve as a belated way 
to introduce myself (I did not do so at the inception of this group, 
for reasons I will style as virginal shyness).

David Roller  |    Bitnet = dr@auducvax            |  "Because we're all
Auburn Univ.  |  Internet = dr@ducvax.auburn.edu   |   in this together."

bionet.plants:
From: donachie@vax.oxford.ac.uk
Subject: Re: heavy metals a few points
Date: 16 Dec 92 22:51:38 GMT

 Cadmium

   In humans and animals Cd interfers with Cu and Zn metabolism.  It competes
with Zn for sites in metalloenzymes that require Zn for function.  It also
blocks sulphydral groups.  

   Interestingly, on the point of Cd competing for Zn sites most metalloenzymes
that require Zn show partial activity if Cd is substituted back in.  Mn, Ni and
Co, can also achieve this effect, with Co being the least disruptive.  

  So my guess is that with Zn deficiency, Cd can reactivate the
Zn-metalloenzymes, and Co would work even better!!!
 
 Kev

Newsgroups: bionet.plants,alt.sustainable.agriculture
From: london@sunSITE.unc.edu (Larry London)
Summary: 260 plants tested for purifiying ability
Keywords: Kathe Seidel of Max Planck Institute
Date: Fri, 18 Dec 1992 07:30:06 GMT

Regarding hyperaccumulators, bioremediation, etc.:

See this article:

HARROWSMITH, The Magazine of Country Life
December, 1988
Number 18
Pages 38-47

"The New Alchemist" John Todd: Transforming Waste With a Rare Mettle
By Donella Meadows

-------------------------