Perchlorates are dangerous!

The Mars Phoenix mission has recently discovered signs of perchlorate salts in the Martian soil. So what are perchlorates?

Perchlorates are salts of perchloric acid, HClO4. In the perchlorate ion, Cl has a valence of +7, significantly higher than the -1 valence state in chlorides (like table salt). This makes it a powerful oxidizer. In the lab setting, perchloric acid is a notorious safety hazard, because it is a powerful oxidizer (ammonium perchlorate is used in solid rocket fuel), and because some perchlorate salts are shock sensitive, and will detonate if struck, dropped, or banged.

The main issue with perchlorate use is that perchloric acid needs to be used in specially designed fume hoods. The reason is that the acid fumes will react with metal ductwork and explosive perchlorate salts can accumulate in the ducts. The Oak Ridge National Laboratory describes their perchlorate decontamination program here, and mentioned another incident where

“a maintenance worker on an Atomic Energy Commission-related project was killed and two others were seriously injured in an explosion touched off by routine use of a small ball peen hammer and 6-inch chisel. The workers were dismantling a perchloric acid fume vent system when the explosion--violent enough to be heard 4 miles away--occurred.”

Marwan Bader, the OHS manager responsible for the decontamination, even deserves the quote of the day:

‘The highest concentration of perchlorates found ranged from 140,000 ppm at an elbow in a duct to 800,000 ppm on the inlet side of a filter housing. "Those are very high concentrations," Bader said’

Some of us like to refer to 800,000 ppm as 80%.

The Oak Ridge clean up has been published by Bader here.

The understatement of the week belongs to Michael Hecht of the Mars Phoenix lander mission, who said, “different types of perchlorate salts have interesting properties that may bear on the way things work on Mars”

I’ll say.

On the other hand, this part of the press release was downright irresponsible:

“It is an oxidant, that is, it can release oxygen, but it is not a powerful one…. The compounds are quite stable and do not destroy organic material under normal circumstances.”

Compare this to the University of Kentucky OHS site, which warns that

“Perchloric acid is destructive to human tissue as well as very reactive.”

Now, folks at NASA may have a different safety culture than we had in my lab, but I don’t refer to compounds that spontaneously combust or explode due to impact as “stable”.

Who is footing whose bill?

Due to increasing wholesale prices, the ACT electricity regulatory authority recently approved a 7.1% increase in electricity prices, which the utility passed on to us retail customers.

In addition to this regulated price increase, the utility also increased the ‘green energy’ surcharge (which is unregulated) by 18%.

All up, the price for green energy customers increases by 10%- much closer to the 11.3% increase sought by the utility.

The optimistic interpretation of this situation is that increased demand has driven up the price of clean energy. The pessimistic interpretation is that the utility is using its green customers to pay for increased dirty energy costs that the regulator didn’t allow it to pass on. Unfortunately, I can’t find any of the wholesale price information necessary to distinguish between these two possibilities. If any of y’all can, please post in comments.

Is organic food radioactive?

Of course it is. All living things contain potassium, and the minor isotope 40K has a 1.25 Ga half life. But pedantry is not the purpose of this blog entry. The real question is whether or not some organic food is more radioactive than it ought to be- especially compared to equivalent non-organic crops.
Organic food is defined as food that is grown without the aid of synthetic fertilizers, herbicides, or pesticides (the definition of synthetic is left as an exercise to the pedants). On the coop farm down the road from my folk’s house, this means improving the soil with chicken poop and bringing in school kids to pull weeds in a rousing synergy of outdoor education and child labor. But chicken shit is not the only source of vital nutrients such as K, N, and P.
There are a few evaporite mines where nitrates are mined, but for the most part, nitrogen fertilizer is fixed from air by industrial processes. Potassium and phosphorous, on the other hand, are generally dug up as rocks, and then processed into a bioavailable form. In all these cases, the processing includes some industrial process which excludes the products from being considered organic. Thus the use of chicken shit or other biological fertilizers, which fix K, P, and N through biological pathways.
Trouble is, this isn’t the only organic solution. According to Manning (2008), some organic farms simply use raw phosphorite rock as a natural fertilizer. Since it isn’t processed, it doesn’t qualify as synthetic, which is great for classification but lousy for whoever has to eat the food. Here’s why.
Most phosphate rocks readily concentrate uranium. Igneous phosphates incorporate U (and Th) into their crystal structures as the magma solidifies, while sedimentary phosphates gradually accumulate uranium from groundwater as it flows through the rock unit. While this is handy for geologists who like to find phosphate deposits using their scintillometers, it does mean that phosphate rocks can be significant sources of ionizing radiation. And the number one rule of radiation safety is, “Do not eat or inhale”.
In theory, the processing of phosphate ore into fertilizer products is supposed to remove the uranium. In practice, the last time I analyzed a retail bag of superphosphate, it had about 50 ppm U. And the process of crushing and reacting the rock with acids is going to release the more volatile or soluble parts of the decay chain (e.g. Radon) even if the U removal is ineffective or ignored. So the radioactivity per phosphorous atom in a synthetic phosphate fertilizer is almost certainly going to be lower than that of the natural phosphate rock. Thus, organic farmer who chose to use natural phosphorite rocks as fertilizer are almost certainly blasting their fields with a higher dosage of radiation than farmers who use an equivalent amount of synthetic fertilizer.
Of course, chickens are not radioactive, and neither is their shit. So the organic classification system lumps low dose chicken shit farmers together with the radioactive phosphate rock hotheads. So a person trying to reduce his dosage needs to know how the food was grown; looking at the certification is insufficient.
Classification is no substitute for knowledge.

Manning D.A.C. 2008 Phosphate minerals, environmental pollution, and sustainable agriculture. Elements, 4, 105-108

Cheaper than mining

According to the NY Times, thieves have been stealing catalytic converters out of cars to sell the PGEs. Maybe science education isn't universally good after all.

Look daddy: entropy

I’ve been trying to teach her that thermodynamics can define entropy more rigorously than a mess on the floor, but my attempts to teach her the significance of dQ/T have not been quite as successful as the hands-on exercises.

Stratigraphic column software

Does anybody out there know of any good, basic, easy to use software that will turn core logs into nice looking stratigraphic columns? It doesn’t have to be fancy, or have the ability to deal with structure- I just need something basic. And as always, cheap would be nice and free would be better. I just want something that will save me the wrist strain caused by drawing forty million little squares all the way down 3000 meters of carbonates.

Genocide or homeopathy?

Radovan Karadzic was captured yesterday, after more than a decade on the run. I heard on the radio this morning that while in hiding, he was a practitioner of alternative medicine. Usually I leave anti-crankery to other people, but I thought this was too good not to mention. Update: The denialism blog has background and photos.
Update: Sean at Cosmic Variance has more.

Sloganeering for Cnidarians

Over at Maribo, Simon reports that scientists at the last ICRS were highly concerned about the impact of anthropogenic carbon dioxide on coral reefs. However, he reports that despite a sense of urgency among the participants at the conference, their attempts at outreach on this matter may not be direct or clear enough. He closes his post with:

Doesn't the community need a far, far stronger message? Any suggestions?

So, in bumper sticker format, here’s my artistically challenged suggestion. Anyone else is welcome to one-up me.