Gordon

Lead sulfide is sparingly soluble in cold water, very roughly at a 1 ppm
level. This is not environmentally dangerous, as this quantity will
easily be captured by ion exchange in a few mm of earth. However, the
sulfide reacts with all acids as the covalent bond between hydrogen and
sulfur is strong, liberating H2S. Whether the resultant salt is
dangerous or not depends on the anion. I agree that HNO3 is quite
unlikely to be present in landfills unless they are chemical dumps or,
possibly, chemical fertilisers are added. However, acetic acid is a
different matter and is quite likely to be present if household or
industrial garbage containing vinegar, alcohol, fruits or sugar were
dumped. Lead acetate is quite soluble. It will also exchange readily in
soil for the lead to be fixed, so the real danger is negligible.

Brian



Davy, Gordon wrote:
> Joe Fjelstad asked, "What is lead sulfide soluble in and might that
> (those?) be commonly found in a landfill in sufficient quantities to
> cause it to go into and be kept in solution?" The answer is that lead
> sulfide is soluble in nitric and dilute hydrochloric acid, (it's
> insoluble in alkalies) -
> see http://ntp-db.niehs.nih.gov/NTP_Reports/NTP_Chem_HS_HTML/NTP_MSDS/Hs_1314-87-0.html.
> Nitric and hydrochloric acid are not to be found in landfills, so you
> don't have to be concerned - PbS won't go anywhere. Remember that the
> sequence was that the activists first decided that they would target
> lead in electronics, and then they went looking for a plausible
> rationale, which is how the just-so story of lead leaching came to
> be. It's dogma, not rigor, for the activists.
>
> I've copied below an item I posted in August last year under the
> title "Lead leaching: science or politics?
> <[log in to unmask]&m=2401&z=4&P=1928" target="_blank">http://listserv.ipc.org/scripts/wa.exe?A2=ind0208&L=Leadfree&D=0&1=Leadfree&I=-3&K=1&X=071A867A753427AE24&[log in to unmask]&m=2401&z=4&P=1928>"
> Incidentally, I don't recall hearing any more about the study, so I
> don't know how things turned out.
>
> Gordon Davy
> Baltimore, MD
> [log in to unmask]
> 410-993-7399
> ------------------------------------------------------------------------
> Fern Abrams has asked for donations of circuit card assemblies to
> support a leaching study conducted by the University of Tennessee and
> funded by the US EPA. The test to be used is presumably the so-called
> TCLP test for leaching of lead, which uses a ?rigged? set of conditions
> totally unrepresentative of what actually exists in a landfill. It
> almost seems that it was concocted to give the answer they were looking
> for. It uses not only a pH far lower, but acetic acid, which does leach
> lead somewhat. Acetic acid is the basis of vinegar, and it is just
> conceivable that there might be some cole slaw right next to a TV?s CRT
> or solder connections in a landfill somewhere. But what of it? With any
> luck, there would be some egg salad nearby that would precipitate the
> lead acetate as lead sulfide. Without luck, the acetate will precipitate
> as a carbonate or sulfate, anions that are available in abundance
> everywhere in the world.
>
> If you were to take the flask containing the leachate from the EPA?s
> test, dump in some dirt (or bubble some carbon dioxide through at the
> risk of global warming) and then check for the new level of dissolved
> lead, it would be far lower. A few weeks ago, Steve Conley alerted us to
> a National Public Radio program that covered conflicting data from a
> Florida university professor (who studied ground-up CRT?s - source of
> funding not identified) and the administrator of a Palo Alto landfill.
> The professor ? who revealed his own agenda by some of his comments of
> advocacy ? found leaching, the landfill did not. As stated also by Chuck
> Dolci, the landfill data are real; the lab data are illusory. It has
> been pointed out repeatedly that the lead level of ground water is in
> the low single-digit parts per billion and is not increasing. What
> exactly is the EPA trying to do? Why not pick a real environmental
> problem to address instead of a phony one?
>
> The EPA ? and professors who accept its money ? should be ashamed of
> themselves for using this test. The project sounds more like politics
> than science; without hearing a lot of explanations of intent I would
> not contribute to it.
>
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