Ask MetaFilter questions tagged with arsenic

I'd prefer the Old Lace

MtDewd — Thu, 21 May 2009 11:31:21 -0800

Are my pressure-treated raised vegetable beds permanently toxic? We have, let's just call them 'tenant farmers'. They've setting up vegetable gardens for us, in exchange for reduced rent. We have some raised beds that were there when we moved in 8 years ago which we have used a little for crops in past years. This year they filled them up with 2 yards of compost and planted lots of things there. Then they were alerted to the fact that the wood is CCA pressure-treated lumber. They won't go near them, won't eat any food grown in them, and advise us not to eat any either.

So I've been looking into sites like this, and I'm thinking I'm not too worried. I see from previous questions here that the general consensus is that I should be. I also looked at the MDSS, and that says I might get higher As levels in produce from the grocery store. (As long as I don't burn or lick the stuff.)

Details- The tags on the wood say Wolmanized- Ground Contact (.40), and have a date of 1993. They probably have been in place since 93 to 95. The beds are about 1'x12' and are either 6" or 12" high, and filled to the top. The compost is of '09 vintage.

Do you think chemicals would still be leaching into the new compost? If you think the beds are hazardous, is the new compost hazardous as well? (It's been in the beds less than a month.) Could it be removed and used elswhere? If I were to replace the boards, would the site still permanently damaged?

How can you detect arsenic in soil from a satellite?

destro — Thu, 15 May 2008 10:50:36 -0800

How is it possible to detect arsenic in soil from a satellite? Fort Reno in DC was recently closed down because they identified arsenic in the soil from a satellite, but I'm not sure how that would be possible. Can you do x-ray fluoresence from space? Is there some other technique that's available that can see beneath the surface of land from that far away?

Sanding a Deck: How little can I get away with?

HK10036 — Mon, 24 Apr 2006 16:47:55 -0800

Sanding a Deck: How little can I get away with? We have a a neglected deck at the back of our house. It's about 700 sq. ft., it was painted at one time but about 70% has worn off. The exposed areas are thoroughly sun bleached and the whole thing is fairly warped, cupped, etc. It's not excactly falling apart, just ugly. It's built of pressure treated wood and I'd guess it to be 20 years old or so. I've used a powerwasher (fun!) to clean the whole thing and against all the warning used the 'laser blast' nozzle to get as much of the remaining paint off as possible. I'm not trying to restore the thing, just clean it up and make it hold up for a few more years.

It's pretty splintery at this point. I plan to use clear deck sealer when weather permits but I suspect it should get a bit of sanding first. I think renting a big drum sander, like you use for floors, would be overkill. Considering ther un-eveness of the surface I imagine it getting caught on corners and grinding off the nailheads that hold the deck together, running amok, etc.

Can I get away with a handheld random orbit sander to just get the high points? Is there some kinds of spongy/flexy sanding device that'd reach below the high points (like the lower areas of a cupped plank)? I don't want to spend more than necessary but I don't want to go through all this to end up with a bed of nails either. I'm a total novice. Any suggestions?