Public Lab Research note

H2S strip placement in Bayou Sauvage NWR, Orleans Parish, LA

by eustatic | June 24, 2012 00:24 24 Jun 00:24 | #2619 | #2619

Today, Shannon and Scott placed 4 x 8 = 32 H2S test strips in a degraded wetland under pump in Orleans Parish, LA.

We attempted to deploy a balloon, but it popped and with it went our onsite Helium supply.

4 of the 8 pvc staffs were short (~4'), and 4 tall (~6'), to get a range of distances from the ground. Because the ground all around is the source, the circular pattern was scrapped for now.

Within each canister pair, different types of openings were made. These will be described in an addendum. There was a single nail-hole canister within every pair. some pairs had their caps removed, with a small piece of ducttape to prevent the test strip from falling out; other pairs had three nail holes punched in their caps.

Scott will make a return visit during the week. Retrieval will begin at S 08, as the holes were made starting at S 08, and after 15 minutes, holes were completed in S 01.

Retrieval will include taping over the holes tightly (or replacement of caps) with black Gaffe tape, placement in box for mailing to their destination.

Video forthcoming.

GPX here:

more photos here

Large detail of holes here

Taller staff (S05 - S08) are 21" and 56" above the surface

G Earth shot showing GPS locations, NW of parking lot. Pump is SE of parking lot. Natural wetlands are to the right of the levee. Note the difference in color. There is a large species difference.

crouched next to short staff (S01- S04; 11" and 33" above the surface)

Shannon labelling and building

stilts gonna getcha


Video here, after a day or so

weather station is here:

Although I think the wind was blowing to the west...

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Too bad about the balloon, but more importantly it's great to see progress on this front! Nice work.

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photos of the bayou rebirth replanting of this site in 2009. neither Spartina nor Scirpus took, but Typha recolonized? this area. or were planted.

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I am interested in repeating this H2S measuring procedure with some modifications. Hydrothermal vents have been suggested as point sources, but I've noticed that this experiment takes place in a marsh. I'm assuming from my reading that this experiment is measuring H2S produced by anaerobic degradation of plant material by bacteria. What is a good set of criteria for identifying a wetland that will produce high amounts of H2S? Can you point me to any papers on this subject? I live in the San Francisco bay area, so there may be many opportunities if brackish marshes can exhibit this behavior.

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copying my mailing list comment back in here:

too interesting a conversation to pass up even on a holiday :-)

so i'm interested in triangulation -- like, how can we independently verify that there is H2S at a test site? I have an electronic H2S sensor connected to an Arduino, and i recently got a temperature/humidity sensor (since the H2S sensor is temp/humidity sensitive too) to correct the H2S readings. I also got a little SD card holder/writer for the Arduino, so I could put together a little package that records H2S and logs the results, for comparison with the strips. Then we'd at least have 2 separate readings of the site. Also:

  1. the H2S sensor I have can only detect like 5 ppm minimum (i think, i'll have to check again) so it's interesting to compare this to either the strip sensitivity or that of the human nose (0.3ppm, see [1] below) . Or the max safe exposure level -- say, 15-20ppm see [2] below.

  2. though this'd be an interesting comparison and a great way to gain confidence in the strip technique, we shouldn't take for granted that the digital sensor is "better" or even particularly authoritative

I may have time on Thursday to try to throw something together and mail it, unless someone else wants to take a crack at it (i could send the parts over?)



[1] [2]

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Jeff, would be excited about a sensor.

I don't think wetlands get above 5ppm...

but eventually we want to target Murphy refinery down the way, so...this sensor would be useful!!

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