H2S point sources and marshes

[Matthew]

Hey there,

Getting into the swing of the public labs....  I also posted the question below here: http://publiclaboratory.org/notes/eustatic/6-23-2012/h2s-strip-placement-bayou-sauvage-nwr-orleans-parish-la#comment-968 as it's not totally clear the best place for discussion of the H2S experiment.  

I am interested in repeating the H2S measuring procedure as done in Bayou Savage 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.

We're also considering a trip to a small hydrothermal vent, which could be dramatic... but it seems like it has less similarity to measuring pathologic conditions.  Then again, there is not question of H2S so it would be a good demonstration.  Welcome thoughts on this as well, would probably head out to the Lassen volcanic area and find a small somewhat isolate hot sulfur hot spring.

m.

[Shannon Dosemagen]

Hi Matthew,

I'm hoping that Scott will jump in and give you a good description as he gave me an excellent one when I asked a similar question. However, I can point you to papers that he posted on the protocol research note that might be helpful as a starting point: http://publiclaboratory.org/notes/shannon/6-22-2012/h2s-test-experimental-protocol-bayou-savage-la. I have a couple of research notes I still need to write up from that test as well, I'll try and get those done tonight and will send you links just so you have them as a reference.

Best, Shannon

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[Scott Eustis]

Matthew, 

I'm away from my work computer for the day, but off my head hydrogen sulfide is generated by certain bacteria in anoxic, reducing conditions in wetland soils.  it is toxic to plants as well, although wetland plants, especially saline marsh plants, can tolerate it.  I have much more knowledge of plants than of soils and biochemistry, but here it goes.  Anyone on the list (Adam?) should feel free to correct me, most of my knowledge comes from reading papers by Dr. Mendelssohn at LSU, and talking to Dr Jenneke Visser at ULL about plants.   There's one in particular that i can forward later. 

basically, if you have collapsing marshes, that are "waterlogged," the soils are likely anoxic and reducing.  if you step or stir the soil, and gas bubbles up, and it smells like rotten eggs, the collapsed/ing marsh is producing some amount of H2S.  The amounts generated are very low compared to industrial sources.

many marsh plants have an alternate metabolism for their roots, which are often underwater, in low or no oxygen conditions.  H2S screws with this anaerobic metabolism.  Often, sulfide is associated with saltwater, as certain ocean salts carry the sulfur.  saltmarsh plants are apparently more capable of dealing with H2S.  So my expectation is that salt marshes will produce more H2S under the collapsing condition.

The site i picked i is not as salty as i would have liked, but I picked it because it was one of the closest collapsed marsh sites to a highway.  It was bare of plants post Katrina, and has received saltwater from Katrina and from a flawed management decision--to flood the polder it sits within with 12 ppt saltwater from Lake Pontchartrain.  

Shannon was inspired by our trip out to Big Branch, where I demonstrated the need for marsh restoration in the area by stepping in the existing waterlogged marsh, which bubbled furiously at each step, and stank of rotten eggs ( i think i have some video of this on flickr).  Bayou Sauvage is not as "bubbly" as that site, but it's very accessible and bubbles.  I think you can see the white foam in some of our photos of Bayou Sauvage. 

The marsh in Bayou Sauvage has already totally collapsed at least once--I have this knowledge from trying to re-plant it post-Katrina.  the area is behind a levee and under pump--this hydrologic alteration has degraded the soil conditions. The area is managed for ducks, not plants--and so the polder is artificially flooded at times, because the migrating ducks like a lot of standing water.  

USFWS and NOSCB had planted bullrushes and Spartina grasses there (see my 2009 photos)-but they didn't take. Typha has naturally colonized the area.  Typha is a plant that is more agnostic of salted and anoxic and sulfuric soil conditions and high water variability.  Its presence, as well as the site's history, indicated to me that this was a good site to try.  The site was under a drainage regime during our trial--the pumps were on.  

the soil at bayou sauvage bubbles and smells a bit rotten eggy--but not as much as Big Branch.  it's a 60 min car ride and 45 min canoe into the site at Big Branch, which takes at lot more planning.  

if the strips aren't sensitive enough to pick up on the H2S that was there--and i'll have to get to my work computer to give you the expected numbers, I would try it again at a more brackish and bubbly site.  i will keep an eye out and ask around.  

perhaps across the bayou from the wetland watchers site out of NORCO.  Or perhaps fountainbleu park a mile off the boardwalk, or off Hwy 11 on the northshore.   the trouble with the more brackish, waterlogged sites in LA that i am familiar with is that most of the good and screwed up ones require a boat (at least a pirogue) to access. The Woodlands Conservancy soils definitely stank of rotten eggs, perhaps we can try there, even though it's freshwater.  That is a former swamp that has been severely drained, and the soils have collapsed.  The older trees are five feet in the air. 

Sara, Shannon, i will make a list of other possible sites to visit and assess if we want to repeat this trial in a bubblier, stinkier site.    

scott

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[Jeffrey Warren]

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:

A. 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.

B. 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?)

Jeff

--------------------

Links: 

[1] http://publiclaboratory.org/notes/warren/9-26-2011/when-hydrogen-sulfide-concentration-reaches-approximately-15-ppm-human-nose-b

[2] http://publiclaboratory.org/notes/warren/9-6-2011/hydrogen-sulfide-detection-fart-detector

[Jeffrey Warren]

Re-raising this -- Sara, you mentioned there were digital H2S sensors you could rent for $20/day? any link to where we could get one?

http://publiclaboratory.org/notes/deepwinter/7-11-2012/draft-experimental-plan-h2s-study-collapsed-salt-marsh

Matthew and I have been chatting in the comments of this post on how to get one to measure the strip technique against. I.e. if we don't have a way to verify that there is H2S somewhere, there's no way to correlate a "spike" in the data with H2S rather than, say, temperature, humidity, some other gas...

Thanks,

Jeff 

[Sara Ann Wylie]

Hi All,

I can ask the community organizer in New Mexico where he is renting from. I
think its a local solution because they have lots of gas field workers in the
area, so I'm not sure everywhere will have personal alert units like this for
rent.

We are calibrating the test strips against draeger tubes which respond only to
H2S. These are going to be co-located with the test strips, so we can make a
distribution curve as described here:
http://publiclaboratory.org/notes/sara/5-21-2012/excellent-geoscience-fieldtest-photostrip-h2s-detection

It would also be interesting to have some kind of continuous digital
monitor in
place, as well, but its not totally necessary to calibrate the test strips.

Sara

>>> USFWS and NOSCB had planted bullrushes and *Spartina *grasses there (see
>>> my 2009 photos)-but they didn't take. *Typha* has naturally colonized
>>> the area. *Typha *is a plant that is more agnostic of salted and anoxic

[Sara Ann Wylie]

Just to follow up on which sensor they've been trying in New Mexico,
they rented
and pilot tested a Industrial Scientific Gas Badge:
Plus:http://www.indsci.com/GasBadgePlus/

>>> USFWS and NOSCB had planted bullrushes and *Spartina *grasses there (see
>>> my 2009 photos)-but they didn't take. *Typha* has naturally colonized
>>> the area. *Typha *is a plant that is more agnostic of salted and anoxic