Hello Chris, Kirk
cool bit of news.
in a similar though sinister vein, surely one of the agro-giants like
monsanto is already working on a gm bacteria or algea to extract
gold from seawater.
Hm. Will nickle do for starters? I came across this below in my files
today - "The Phytomining of Certain Elements".
Best
Keith
-chris b.
Date: Sat, 25 Jun 2005 07:32:44 -0700 (PDT)
From: Kirk McLoren <[EMAIL PROTECTED]>
To: biofuel <Biofuel@sustainablelists.org>
Subject: [Biofuel] Money that grows on crops
<http://csmonitor.com/2004/0415/p17s02-sten.html>http://csmonitor.com
/2004/0415/p17s02-sten.html
Money that grows on crops
By Jen Ross | Contributor to The Christian Science Monitor
CONCEPCIÓN, CHILE He can't quite make money grow from trees, but a
New Zealand scientist has devised a way to harvest gold from plants.
The idea: Use common crops to soak up contaminants in soil from
gold-mining sites and return the areas to productive agriculture.
The gold harvested from the process pays for the cleanup - with
money left over for training in sustainable agriculture.
The Phytomining of Certain Elements
Cooperative Research and Development Agreement No. 58-3K95-7-570
between
USDA-Agricultural Research Service
The University of Maryland
The Environmental Consultancy of the University of Sheffield
and Carol Nelkin, Trustee
Final Summary Report
by
Rufus L. Chaney, J. Scott Angle, and Alan J.M. Baker.
July 26, 2001 + Revised Final Patent Report
INTRODUCTION:
Mining of metals using traditional technologies often caused
contamination of surface soils, and left solid waste deposits rich in
metals. And soils surrounding metal smelters have historically become
heavily contaminated with Ni and other elements in these ores. When
such soils require remediation, the default remediation technology
(soil removal and replacement), costs on the order of $3 million per
hectare-30 cm deep. Alternatives to this expense are needed to deal
with such contaminated soils.
The existence of natural plants which hyperaccumulate (absorb and
translocate to shoots, reaching over 1000 ìg Ni/g dry tissue when
grown on soils where the plants occur naturally) Ni and Co offered an
alternative method to remediate such soil, a new technology called
phytoextraction. In particular, a number of Ni hyperaccumulator
species had been shown to accumulate over 2.0% Ni, and could be used
as bio-indicator plants to find Ni rich serpentine soils. The
USDA-ARS, University of Maryland-College Park, and the Environmental
Consultancy of the University of Sheffield collaborated in inventing
a method to use such natural plants to phytoextract Ni from
contaminated soils which could also be applied to mineralized
ultramafic soils which are extensive on Earth. Also, all Ni consumed
in the US is imported or recycled because US Ni mines have closed. Ni
is a strategic metal, and phytomining the extensive serpentine soils
in the northwestern US and some other states could allow the US to
produce Ni metal needed as a strategic resource.
Viridian Resources, LLC, learned of the possible application of the
phytoextraction technology to Ni and Co, and entered a Cooperative
Research and Development Agreement with ARS, UMD and ECUS to convert
our basic scientific observations into practical commercial
technologies for phytomining soil Ni and Co.
CRADA Objective:
The goals of this Agreement were to cooperatively conduct
planning, research, development, testing and evaluation activities
that are needed to develop plant genotypes andmanagement practices
needed for commercial phytomining and phytoremediation (collectively
called phytomining) of nickel and cobalt from serpentine or lateritic
serpentine soils, soils rich in Ni + Co, or Ni+Co contaminated soils;
to identify locations of such land needed to commercialize
phytomining of Ni and Co; to develop methods such that phytomining
could be an economically competitive technology for decontamination
of soils, and for production of Ni ore; and to develop methods to
recover Ni from the plant biomass produced by phytomining.
Accomplishments:
The CRADA cooperators developed a plan to domesticate a Ni
phytomining crop, a crop which accumulates Ni from contaminated or
mineralized soils at an annual rate rapid enough to achieve
environmental remediation of contaminated soils, or to provide a
phytomining alternative to traditional mining by surface pits.
Ultramafic or serpentine soils form from serpentinite rocks, and
because the rocks are low in nutrients, many plants cannot grow on
these soils. The soils are extensive in the northwestern US where
more than a million acres are known to exist in CA and OR.
Preliminary investigations and literature review indicated that these
soils contained adequate Ni to serve as a phytomining substrate which
could provide more annual value in growing phytomining crops as Ni
ore than for growing crop plants on fertile soils of this region. For
example, if these plants could be grown as a practical crop which
accumulated more than 2.0% Ni (20 g Ni/kg dry matter), at moderate
yields of biomass (say 10-20 t dry matter/ha), the amount of Ni in
the harvestable shoots would be 200-400 kg/ha. The biomass could be
burned as an energy source, and the Ni in the ash would be present at
20-40% of the ash, a very high grade Ni ore, higher than all
commercial ores from traditional mining. Because these soils are so
infertile, land owners are generally unable to produce crop plants
other than low grade pastures or forests worth $50-200/ha-year. Ni
metal in the market varies in value over time, with a 10-year average
about $9/kg. Thus the value of Ni in the ash could be on the order of
$900-$1800/ha, far higher than other crops which could be produced on
the serpentine soils, higher even than for major farm crops on good
soils in the same region. Thus if a phytomining crop could be
developed, farming practices identified to reliably produce high
annual yields with high Ni concentrations in the harvestable biomass,
a valuable alternative crop for these soils would be available to
land owners. Further, commercial Ni ores are ordinarily at least 2.5%
Ni in a silicate rock matrix rich in Fe and Mn which increase the
cost of producing Ni from ore. But plant ash contains little which
would interfere with recovery of Ni and production of Ni metal from
the ash with 20-40% Ni, and the crop could be economically produced
as a Ni-phytomining crop on soils with as low as 500 mg NI/kg, a
concentration at which the soil would be "overburden" for normal
metal mining.
In order to achieve the CRADA goals, the cooperators
collected germplasm for a number of Alyssum species and other Ni
hyperaccumulator species from serpentine soils where they occur
naturally in southern Europe. Seeds were collected from individual
mother plants growing in different locations and different ecological
settings at a general location in order to collect genetic diversity
for adaptation to different soil and climatic environments. Large
seed lots were collected from several locations to have seeds which
were uniform enough to be used in greenhouse and field testing the
effects of agronomic and soil variables on effectiveness of Ni and Co
phytoextraction.
Because the plants occurred in different locations, on soils
with different Ni levels and other soil properties, all germplasm
needed to be evaluated under uniform conditions to characterize the
ability of that genotype to germinate and survive, to produce a high
shootbiomass annual yield which was upright enough to harvest, and to
accumulate high levels of Ni in the shoot biomass to support economic
phytomining. Practical evaluation of genotypic response could only be
attained in the field after full growth cycles which allowed
expression of the genetic diversity of the collected seed.
Soil management and fertility for the field genotype testing
was based on greenhouse studies of soil fertility and pH variables
for achieving high yields in ultramafic or contaminated soils. The
greenhouse studies illustrated that wild Alyssum murale and other
species studied could accumulate adequate phosphorus for a full yield
if soils received only low P-fertilizer rates. The soil test
phosphate levels required for a full yield of Alyssum murale were
below that required for production of crop plants. Similarly,
although the natural serpentine soils contain insufficient levels of
Ca to support crop plants, Alyssum murale accumulated adequate Ca for
a full yield without addition of Ca fertilizers. But because
harvesting the biomass would remove Ca from the soil, over time Ca
fertilizers would have to be applied to maintain productivity.
Although these plants are adapted to the high magnesium serpentine
soils, they both tolerate high Mg, and do not require exceptionally
high soil Mg. And levels of N, K and S required for maximum yields
were not unusual compared to crop plants.
Methods to plant and transplant the crop, and herbicides to
control weeds in fields of phytomining crops were identified by
experiments. Different planting dates were identified for irrigated
and non-irrigated management of Alyssum murale in both the serpentine
soils of northern CA and southwestern OR where Mediterranean climate
patterns limit soil water availability in summer. Alyssum murale
evolved on land in a Mediterranean climate across southern Europe,
and normally enters a dormancy period after flowering in Spring and
setting seed. The crop normally regrows when rainfall returns in the
Fall. But when grown with irrigation, or at a location with summer
rainfall adequate to maintain plant growth, the Alyssum phytomining
crops can be grown year-around (but will not reproduce without
vernalization by cold short day conditions).
Besides needing to learn how to economically produce Alyssum
murale biomass, an important goal was breeding of improved cultivars
based on testing of the collected wild germplasm. After rating the
collected genotypes for growth pattern (upright vs. prostrate),
aboveground biomass, shoot Ni concentration, retention of leaves
after initiation of flowering, and other characteristics which an
experienced plant breeder would include in improved cultivars, a
breeding program was begun to develop improved cultivars for
commercial use. Research showed that these species were
self-incompatible, so typical pedigree breeding could not be
conducted. Rather, recurrent selection was begun by making all
possible crosses among the 10 best plants of the 10 best genotypes
under test. Fertilization of flowers was conducted both by hand and
with the aid of bee hives. These seed have been used to conduct the
next cycle of recurrent selection, and improved cultivars are under
development.
Examination of soil management variables identified several
factors which could be managed to maximize annual biomass Ni
quantity. Because the market value is a combination of biomass energy
and high grade Ni ore (ash), one seeks to optimize the value of the
crop. Present value of biomass burned to heat steam to generate
electricity is as great as the cost of growing the crop and marketing
the crop, but the value of Ni in the biomass could be 10 times the
value of the biomass energy alone. Thus shoot Ni was the optimized
value for determining the combination of genetic traits to be
combined by breeding and by management practices.
Because soil pH very strongly affects plant uptake of Ni, and
potential for phytotoxicity of Ni, the effect of soil pH on
solubility of Ni and on uptake of Ni was tested in the greenhouse
andin the field. Such tests were conducted both on contaminated soils
from Port Colborne, Ontario, in cooperation between the CRADA parties
and Inco Ltd., and on Oregon serpentine soils. In all cases, the
solubility of Ni dropped as soil pH increased. But in nearly all
soils tested, increasing soil pH actually caused higher Ni
concentration in shoots, and had little effect on biomass yields such
that liming increased value of the biomass, and addition of sulfur to
acidify soils decreased the value of the biomass. Crop plants
included in these studies clearly showed that increasing soil pH
decreased shoot Ni and decreased the potential for Ni phytotoxicity
to crops. Thus, the effect of soil pH on Ni phytomining was opposite
to that found for crop plants. Plant uptake of other cationic
microelements is also usually decreased by liming soils, including
Zn, Mn and Co. Because the effect of liming on uptake of Zn, Mn and
Co by Alyssum murale was similar to that of crop plants, opposite the
greater uptake of NI with liming seen for Alyssum, this finding
indicates that phytomining of both Ni and Co cannot be maximized at
the same time. Rather, one can phytoextract Ni at neutral soil pH and
then phytoextract Co after acidifying the soil. Further, study of Co
phytoextraction indicated that high soil Ni inhibited Alyssum uptake
of Co such that one would be expected to phytomine Co only after
phytomining Ni. Co has higher value per kg, but occurs at much lower
concentration in serpentine soils that does Ni, so the initial
phytomining approach would be for Ni.
In practice this offered a positive value because to
ameliorate Ni phytotoxicity, one usually raises soil pH to reduce
plant uptake of Ni. Thus, liming soils to allow normal growth of
other wild or crop plants is compatible with phytomining Ni from the
same soils using Alyssum murale and similar Ni hyperaccumulators.
Other agronomic factors were examined. Normal application of
fertilizer for production of crops such as corn, wheat, or canola,
following traditional fertility management guidance for the region,
allows production of maximum annual biomass yields of Alyssum murale.
Because the plant will normally be growing from seed or seedlings
transplanted at the end of the summer dry season in Mediterranean
climate regions, one should apply only part of the fertilizer-N in
the Fall; than after winter rainfall, the supplemental N fertilizer
should be applied after plant growth has increased in Spring. And
because the leaves have about double the concentration of Ni as the
stems and petioles, scheduling of harvest should occur at early
flowering before leaves start to drop during seed filling. As noted
above, for breeding improved cultivars, retention of leaves at
initiation of flowering was considered a desired trait. Normally the
plants would be harvested without development of viable seed.
Studies were conducted to learn the best spacing of rows and
of plants within a row (planting density) for optimum economic yield.
These tests utilized the Nelder design, and showed that when plants
were placed to close together, a biomass yield appreciably declined.
Based on these studies and practical planting tests, use of rows
about 60 cm apart, and plants about 30 cm apart within rows afforded
an effective biomass yield with maximum Ni for the soil management
conditions.
The ability to prevent adverse effects of weeds on a yield of
Alyssum biomass was examined in greenhouse and field tests. Preplant
incorporated herbicides for Brassica crops were effective in limiting
weed germination and growth for some period after planting. However,
the initial growth from seeds of the Alyssum murale and other
phytomining plants under development, and weeds can get ahead of the
planted Alyssum. Post-planting herbicides were identified to control
grasses in Alyssum murale, and some ability to control non-Alyssum
dicot species was found in commercially available chemicals.
Alternatively, transplanting Alyssum seedlings into fields treated
with pre-plant herbicides allowed the Alyssum to get ahead of the
weeds and effectively control weed competition (with application of
the grass control chemicalsas needed). Although improved weed control
may be found with other chemicals not yet tested, the combination of
practices identified were quite effective in limiting loss to weed
competition.
Integrating Alyssum phytomining crops into farming practices
and climate cycles offered another set of choices and limits. We
found that if the crop can be planted early enough in the Fall to
allow thorough establishment, the plants can vernalize and grow
rapidly and tall in the spring (when the vernalized plants "bolt"
before and during flowering), assisting with harvest. Alternatively,
if water is available for watering of seedlings, seedlings can be
produced and the seedlings transplanted to the field at the beginning
of Fall rains. This approach allows growers time to produce seedlings
during the period when the plants cannot be grown without irrigation,
yet allow them to transplant strongly growing seedlings to the field
which gives advantages against weeds. In Mediterranean climate areas,
the plants would then grow in the Fall, survive the winter, and grow
well in Spring before bolting and starting to flower in June. At that
time, before many leaves have fallen, the crop can be cut, dried in
the field briefly, and baled or otherwise collected so it can be
hauled to a biomass burn facility to produce energy and ash.
Alyssum phytomining crops can be harvested using traditional
farming equipment used to cut and bale hay crops. Experience in OR
indicated that a sickle bar mower can cut the crop and allow
recovering most of the biomass from the cultivars under development
(more upright characteristics were selected during breeding). After
the crop dried about two days in the summer sun, the biomass could be
baled using standard commercial baling machines. The bales could be
stacked in the field until ready for marketing.
A number of production systems were considered for
phytomining cropping. For existing landowners, the one could contract
for using the patented seed and methods to produce crops which the
licensee would agree to purchase for high enough value to obtain
production by land owners (this model is that used for many vegetable
crops by commercial food processors). Alternatively, one could
purchase or lease serpentine soils for production of phytomining
crops. In the case of Ni contaminated land, one could offer a service
to phytoextract Ni from contaminated soils. Actual best production
approaches depend on land ownership, markets for the biomass or
biomass ash, and agronomic experience of persons able to follow the
common production practices identified for production of Alyssum
phytomining biomass.
In cooperation with Inco Ltd, the application of Ni
phytomining to agricultural soils contaminated by emissions of a Ni
refinery at Port Colborne, Ontario, was tested using the optimum
practices identified by CRADA R&D. Selected genotypes of Alyssum
species were grown on several soils containing from 600 to 4600 mg
Ni/kg, without and with limestone addition to maximize Ni
accumulation. As on the serpentine soils, addition of limestone
strongly favored Ni hyperaccumulation. Although the tests clearly
showed the power of Alyssum to phytoextract Ni from these smelter
contaminated soils, excessive soil moisture in very poorly drained
soils in one rainy Spring was found to require some adaptation in
drainage or production practices for phytomining to be successful on
these soils in practice. To assist Viridian and Agricultural
Cooperatives Development International (Washington, DC), CRADA
scientists prepared a Manual for Ni Phytomining to apply CRADA
technologies to phytomine Ni from serpentine soils in Turkey.
Recovery of Ni from the biomass or biomass ash was tested
experimentally, but not at commercial scale. Evidence available
indicates that Ni in the ash can be dissolved, and the Ni recovered
by two common commercial methods for production of Ni metal.
One question raised about phytomining using hyperaccumulator
plants was whether thehigh Ni concentrations in plant material would
comprise an attractive nuisance to wildlife or livestock.
Observations relevant to this question were made by the
botanists/ethnologists who collected the genotype seeds across
southern Europe including areas where cattle, sheep and goats were
grazing in the same fields. And in CRADA test fields in OR and
Ontario, where deer entered the fields and ate crop plants and other
weeds. But neither wildlife nor livestock were observed to consume
the Alyssum murale and similar Ni hyperaccumulators. This pattern is
supported by observations of others who farmed such areas in southern
Europe. This pattern was not unexpected based on basic studies by
others who found that the apparent benefit which Ni hyperaccumulator
species obtain from spending energy to accumulate soil Ni in leaf
tissues is defense against plant diseases and chewing insects. These
plant species are commonly "endemic", growing only on serpentine
soils, because they may have given up other defenses against disease
and insects when they evolved the ability to accumulate Ni to provide
this defense. Whether plant structure (high in trichomes) makes the
plant tissues unpalatable, or Ni in the plants causes an unpleasant
experience to the consumer has not been established, but to date
observations show no risk to local animals where Ni Alyssum
phytomining crops are grown.
All agreed CRADA R&D required of ARS, UMD and ECUS was
completed satisfactorily with the field demonstration of cost
effective Ni phytomining from Ni-mineralized soils.
[A whole bunch of patents pending and citations follow, I'll post
them on if anyone's interested. - KA)
_______________________________________________
Biofuel mailing list
Biofuel@sustainablelists.org
http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org
Biofuel at Journey to Forever:
http://journeytoforever.org/biofuel.html
Search the combined Biofuel and Biofuels-biz list archives (50,000 messages):
http://www.mail-archive.com/biofuel@sustainablelists.org/
