[ RadSafe ] Fw: Uranium contamination
Dan W McCarn
hotgreenchile at gmail.com
Thu Mar 25 02:42:09 CDT 2010
Dear Barbara:
1. The Natural Reactors were at OKLO, in Gabon, in Archean or Early
Proterozoic rocks (1.7 - 2 billion years ago). The concentration of U235
was significantly higher than today – about 3%. The moderator was natural
water and the ore concentration quite high. These “natural reactors” make a
good model for waste repositories. The same geologic / geochemical
mechanisms that emplaced the ore also made it a good repository of
radionuclides. The plutonium produced did not travel more than 3 meters or
so. There is a good IAEA publication on Oklo.
2. “Uranium, like most heavy metals has a high chemical toxicity.”
Well, I’d place quite a few other metals above uranium in toxicity. In
fact, looking at mill-worker data, they were pretty healthy in spite of
relatively high serum concentrations of uranium. Arsenic, for instance, is
not only a heavy metal poison at high concentrations but also a carcinogen,
mutagen, etc. Arsenic and uranium have about the same crustal abundance.
Gold, platinum, silver, copper (all heavy metals) are commonly used “safe”
metals. Years ago, I was involved as an expert witness in a case involving
arsenic contamination in Georgia. The contaminated pond contained almost 0.5
% Arsenic and was caused by a chicken hatchery using NaOH – based cleaners
emptying into a septic-tank leach-field (pH = 12). The fluids hydrolyzed –
leached - the arsenic from the arsenopyrite in the limestone. In that case,
every foal exposed to arsenic was either auto aborted or died shortly after
birth.
3. The Redding Prong does indeed contain high levels of uranium
(radon).
4. Which heavy metal deposits? Gold / arsenic association is known
worldwide, and cancer related to arsenic can be epidemiologically correlated
to gold mining districts. Nevada, for instance, has pretty high levels of
arsenic in drinking water. Looking at comparative risk, if reducing the
arsenic in Albuquerque’s drinking water by 10 ug/l to meet federal standards
means also reducing the water hardness (magnesium & calcium) by 10%, then
the increased risk of cardiovascular disease most probably far outweighs the
reduction in risk from arsenic.
5. When heavy metals bio-accumulate in plants, they can cause
significant problems. Selenium poisoning in cattle is one example; another
is the hyper-accumulation of Cs & Sr in mushroom caps. Eating mushrooms
around Chernobyl can result in a high internal dose. Lack of selenium in
cattle (a much more likely issue) results in white muscle disease and has a
much larger area associated with it. Selenium poisoning frequently occurs
is in soils associated with marine black shales and equivalents. Uranium is
associated with these shales but has never caused a toxicity problem because
it doesn’t tend to bio-accumulate like selenium.
6. Uranium has a number of pathfinder elements including arsenic,
selenium, molybdenum, rhenium, fluorine, phosphorous, scandium, & rare
earths. Deposits that are redox controlled will concentrate some metals
that are redox sensitive. Other minerals e.g. calcite, though not redox
sensitive, are mobilized and reconcentrated via bacterially mediated
reactions with Fe+2/Fe+3 with thiobacillus ferrooxidans. The pH drops to
around 3 and the bacteria seem quite happy to live in diluted sulfuric acid.
This same mechanism drives acid-sensitive metals forward as well, or at
least increases the kinetics of the reactions. Those metals that have lower
solubility in reduced environments will concentrate in a manner spatially
correlated with uranium, that is if the source for those metals is present.
7. Massive sulfide, coal, and other deposits that contain significant
pyrite will cause acid leach and remobilization of metals. However, uranium
does not tend to be associated with massive sulfide deposits except possibly
at the margins of these deposits.
8. Almost all deep mines have, to some degree or another, issues with
radon, the Cornish Tin Mines being an example. This is commonly attributed
to uranium mines, but it is not an exclusive issue. Note EPS’s concern for
radon accumulation in basements!
9. “Some of the areas in Pennsylvania have been mined for zinc” are
contaminated. Yes, and we had a project in Leoben, Austria to examine the
extent of environmental contamination caused by BRONZE AGE miners and
foundries. The principle contaminant was arsenic which was concentrated in
the hillsides about the same level as the thermal inversions. Stated again,
the smoke from the foundry would rise to the level of the inversion and the
soils on the hillsides at that level would receive a significant amount of
arsenic. I suspect that it was not the mine in Pennsylvania that caused the
problem so much as the foundry practices. But Zinc occurs as part of the
gangue minerals which will inevitably include (sulfides of Fe, As, Zn, Pb,
Cu) pyrite, arsenopyrite, sphalerite, galena, chalcocite, chalcopyrite,
etc.
Since this last subject was principally on Bronze-Age Austrian mining
issues, let me close with the traditional miner’s saying:
Glückauf!
Dan ii
--
Dan W McCarn, Geologist
2867 A Fuego Sagrado
Santa Fe, NM 87505
+1-505-310-3922 (Mobile – New Mexico)
<mailto:HotGreenChile at gmail.com> <mailto:HotGreenChile at gmail.com>
HotGreenChile at gmail.com (Private email)
_____
From: blreider at aol.com [mailto:blreider at aol.com]
Sent: Wednesday, March 24, 2010 23:38
To: hotgreenchile at gmail.com; radsafe at health.phys.iit.edu
Cc: mmiller at sandia.gov
Subject: Re: [ RadSafe ] Fw: Uranium contamination
Dan,
Not sure about toxic levels of U in the US, there are so many .orgs
dedicated to this you cannot find data. So perhaps you, as a geologist know
more.
I am only going on ancient memories but what about the Redding prong area in
PA and western regions mined for heavy metals having levels of U that pose
toxicity problems? Some of the areas in Pennsylvania have been mined for
zinc etc. and the USACE says whole towns are highly contaminated with
everything under the sun. Also, mined areas that have been turned acidic I
believe sometimes have elevated levels of U and other heavy metals in
groundwater. Uranium, like most heavy metals has a high chemical chemical
toxicity. The question as posed didn't specify radiological danger. When
I did a search online I found quite a few articles about arsenic from
U-mines being toxic, so perhaps the U is not as toxic as other metals used
in mining.
And where is that natural plutonium reaction area in Africa I read of years
ago. If true, it had to at one time have large concentrations of U-235 and
Unat. <http://www.ead.anl.gov/pub/doc/Plutonium.pdf>
http://www.ead.anl.gov/pub/doc/Plutonium.pdf
Barbara Reider, CHP
-----Original Message-----
From: Dan W McCarn <hotgreenchile at gmail.com>
To: radsafe at health.phys.iit.edu
Cc: 'Miller, Mark L' <mmiller at sandia.gov>
Sent: Wed, Mar 24, 2010 5:39 pm
Subject: Re: [ RadSafe ] Fw: Uranium contamination
Dear Group:
OK, I'll step in on this one! About 1/4 of the US is directly underlain
with uranium-bearing soils and rock, specifically those underlain by the
Chattanooga Shale, Pierre Shale or Mancos Shale. Typical concentrations of
uranium in these marine black shales are 80-120 ppm or about 0.01% U.
Phosphorites also contain significant uranium at about the same
concentration. Florida has abundant occurrences / deposits of uraniferous
marine phosphorites.
That being said, the uranium in these rocks are fairly tightly bound
organically. Uranium which might occur in other rock types would tend to
lose uranium fairly quickly on exposure to meteoric conditions except under
certain conditions (availability of vanadium).
We had a discussion about this subject two or three years ago including
calculations for the "English Garden". I did a recalculation for
Chattanooga shale soils about that time.
There are other modes of reconcentration in soils including pedogenic
calcretes which tend to concentrate U by evaporative pumping in the desert
SW. Also called hardpan, duricrusts, pedocretes and caliche, they can be
formed from silica (silcretes), calcium carbonate (calcretes), or gypsum
(gypcretes). The Ogallala Fm from Texas to the Dakotas contains uraniferous
pedogenic silcretes.
That doesn't answer your question, but perhaps covers some of the ranges of
soil concentrations associated with a common rock type.
Dan ii
--
Dan W McCarn, Geologist
2867 A Fuego Sagrado
Santa Fe, NM 87505
+1-505-310-3922 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email)
-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jerry Cohen
Sent: Wednesday, March 24, 2010 15:06
To: Miller, Mark L; radsafe at health.phys.iit.edu
Subject: Re: [ RadSafe ] Fw: Uranium contamination
Can anyone suggest any reasonable set of conditions where soil contamination
with uranium might constitute a credible threat to health and safety ?
Jerry Cohen
PS: It is now springtime, or as Al Gore suggests, "Proof of global warming"
________________________________
From: "Miller, Mark L" <mmiller at sandia.gov>
To: Jerry Cohen <jjcohen at prodigy.net>
Sent: Wed, March 24, 2010 10:16:53 AM
Subject: RE: [ RadSafe ] Fw: Uranium contamination
As with everything, the answer is, "It depends." A pathway analysis (like
RESRAD) can tell you if a problem exists, it's magnitude and the most likely
pathway(s) of exposure. The devil's in the dose. Armed with that, you can
THEN ask, "Now what"? The "what" might be "no action" or appropriately
targeted action.
-----Original Message-----
From: Jerry Cohen [mailto:jjc105 at yahoo.com]
Sent: Tuesday, March 23, 2010 4:24 PM
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] Fw: Uranium contamination
Does the existence of Uranium contamination in soil constitute a credible
threat to heath and safety, or is this just another costly federal
"feel-good" program? If such uranium contamination is really a problem, what
should be done with the millions of tons of uranium in the oceanic coastal
waters. We even are allowing children to swim in it.
Jerry Cohen
________________________________
From: Cary Renquist <cary.renquist at ezag.com>
To: radsafe at health.phys.iit.edu
Sent: Fri, March 19, 2010 6:10:01 PM
Subject: [ RadSafe ] Argonne scientists seek natural remediation for
uranium-rich sites
They are looking to understand and optimize the conditions under which
bacteria can
transform U(IV) <soluble> to U(VI) <insoluble>
Argonne scientists seek natural remediation for uranium-rich sites
Link http://j.mp/b3AHAh
Cary
--
Cary.renquist at ezag.com
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