Doing Diatoms

[billbillt]

A person could spend all day looking at these slides... There is SO much to see here!!..

BillT

[KurtM]

I'm sure you've run across it too, but in references found in books and on the web the advice is given to AVOID sand and dirt when collecting diatoms because of the great difficulty, bordering on impossibility, of separating them. But I have never been any too clear on just how one might go about collecting only sandless and dirtless diatom samples without severely limiting what one is able to bring to the lab?

For me, having mineral and/or other detritus present in some finished strews is just part and parcel of this nutty endeavor, and obtaining really clean strews is like a rare bonus to be relished, the exception rather than the rule.

Of course, if one sends slides to colleagues, only the cleanest go, so that recipients think you're better than you really are.

Bill: Yes, some people DO spend all day looking at these slides.

[zzffnn]

I am guessing one could possibly use a thin razor blade to slice off thin/soft surface of diatom mud, which should have more diatom than mineral particles. Diatoms live slightly above the mineral particles, I assume. A non discriminatory brush would remove too much sand.

With mineral particles as small as diatoms, they would be difficult to remove after harvest. Density wise, sands are only slightly denser than diatom skeletons. And sands are resistant to any diatom cleaning reagents or procedures (you would have to destroy diatoms first, before you destroy mineral particles).

[rnabholz]

A person could spend all day looking at these slides... There is SO much to see here!!..

BillT

Kurt and I had a discussion recently about scanning these slides.

I have found that the experience changes with each level of magnification. I usually start at 20x, very easy to see the large forms, usually great targets for photography, and the mid sized ones are still showing enough detail to be interesting and catch your eye.

Scan at 40x and those mid sized ones are starting to give up their secrets, and you become aware of the smaller ones with their own intriguing shapes and structure.

At 100x, every field is chock full of amazing sights, the big ones are parading their finest of details, the small ones are daring you to try and coax out their incredibly minute lines and dots.

Yes, you can get totally lost for hours......

And just you TRY and decide which view you will NOT photograph.

[rnabholz]

I'm sure you've run across it too, but in references found in books and on the web the advice is given to AVOID sand and dirt when collecting diatoms because of the great difficulty, bordering on impossibility, of separating them. But I have never been any too clear on just how one might go about collecting only sandless and dirtless diatom samples without severely limiting what one is able to bring to the lab?

For me, having mineral and/or other detritus present in some finished strews is just part and parcel of this nutty endeavor, and obtaining really clean strews is like a rare bonus to be relished, the exception rather than the rule.

Of course, if one sends slides to colleagues, only the cleanest go, so that recipients think you're better than you really are.

Bill: Yes, some people DO spend all day looking at these slides.

Yes, sort of like telling someone to stay dry while swimming....

Around here the material I gather is found on rocks and submerged sticks or logs, in the middle of silt laden streams. Minerals WILL happen.

I guess the idea is to try common sense strategies like looking for faster moving sections of streams where silt is less likely to settle out. Making sure the bottom of a rock or stick doesn't carry stream bed sand into the harvesting tray, etc.

I promise you will get a full serving of native mineral content with each and every strew slide I produce.

[Peter]

Hi Rod,
If the diatoms are still alive when they arrive at the lab they may be separated from the minerals and other non mobile detritus by placing the whole sample in the shade and allowing the diatoms access to an area which is illuminated brightly. The diatoms will tend to migrate out of the unwanted material and congregate near the light from whence they may be harvested.
The method and apparatus used to achieve this is limited only by your ingenuity.
Hope this helps.
Peter.

[rnabholz]

Like moths to a flame! Brilliant

What percentage of Diatom species are motile? I assume those are the only ones that this process will work with?

[billbillt]

Of course, if one sends slides to colleagues, only the cleanest go, so that recipients think you're better than you really are.

Hi Kurt,
There is certainly nothing wrong in sending friends and colleagues the best.. That way you can proudly share your work... A good thing!.. A person deserves recognition for good work....

BillT

[KurtM]

Bill, while I hear what you're saying and appreciate the sentiment, my little quip was in jest; if you only send samples without detritus, you can't send the full range of types you wish to share.

Rod, I had the same reaction: seems like the motile types would migrate, but what about the sessile ones? Another trick is to look for trash in the water, and take scrapings from bottles, cans, and the like. Michel sent me some photos of him suspending a piece of glass from a pier, and retrieving it some time later after it had become covered in our favorite stuff: brownish-green slime. Also, don't forget about slime on aquatic vegetation. I have also heard of taking mud to the lab, placing some in a suitably shallow container, covering it with tissue, exposing to light from above for a day or two, then peeling the tissue off the mud and wash the diatoms off the tissue.

[zzffnn]

Kurt,

Did Michel tell you how he cleaned his diatom samples, or is it commercial secret? His diatoms are impossibly clean.

The diatom collection methods you mentioned make great sense. When I mentioned using a razor blade in my previous post, I meant exactly slicing off surface of vegetation and avoiding real mud.

[rnabholz]

Bill, while I hear what you're saying and appreciate the sentiment, my little quip was in jest; if you only send samples without detritus, you can't send the full range of types you wish to share.

Rod, I had the same reaction: seems like the motile types would migrate, but what about the sessile ones? Another trick is to look for trash in the water, and take scrapings from bottles, cans, and the like. Michel sent me some photos of him suspending a piece of glass from a pier, and retrieving it some time later after it had become covered in our favorite stuff: brownish-green slime. Also, don't forget about slime on aquatic vegetation. I have also heard of taking mud to the lab, placing some in a suitably shallow container, covering it with tissue, exposing to light from above for a day or two, then peeling the tissue off the mud and wash the diatoms off the tissue.

I like the idea of suspending a glass bottle or something similar. Plants are another good idea, those should disappear in the chemicals.

[zzffnn]

Like moths to a flame! Brilliant

What percentage of Diatom species are motile? I assume those are the only ones that this process will work with?

Rod,

It wouldn't hurt to ask people who maintain that diatom database:

http://westerndiatoms.colorado.edu/about/contact_us

It is a good question, by the way.

[rnabholz]

Like moths to a flame! Brilliant

What percentage of Diatom species are motile? I assume those are the only ones that this process will work with?

Rod,

It wouldn't hurt to ask people who maintain that diatom database:

http://westerndiatoms.colorado.edu/about/contact_us

It is a good question, by the way.

Not exactly the definitive last word, but this from Wikipedia:

Most diatoms are non-motile, as their relatively dense cell walls cause them to readily sink. Planktonic forms in open water usually rely on turbulent mixing of the upper layers by the wind to keep them suspended in sunlit surface waters. Some species actively regulate their buoyancy with intracellular lipids to counter sinking.

It sounds like motile species are the minority for sure.

[KurtM]

Did Michel tell you how he cleaned his diatom samples, or is it commercial secret? His diatoms are impossibly clean.

Finally remembered to answer this question: real diatomists who are actually educated past the third grade and know their chemistry use harsh exotic caustics and oxidizers under fume hoods and such to clean diatom samples. Mere mortals like me and Rod use grocery store chemicals and do the best we can with them because we don't crave the excitement of risking life and limb using dangerous substances for which we have no training in handling.

So while our results may be somewhat sub-par, the processes we use are accessible and infinitely better than giving up and doing nothing.

Plus, Michel's been at it a lot longer than Rod or I.

[zzffnn]

Thank you, Kurt.

I was just wondering if Michel used incineration. You and Rod's diatom mounts are very close to the pros already (waayyy better than "sub-par").

[rnabholz]

Just to comment on processes.

Kurt is correct, many Diatomists use some pretty powerful acids and other strong chemicals that frankly cause me to be a bit unsettled when I think about handling them as I really have no training. It is hard to justify exposing myself to possible serious injury for something is that is a fun, but completely optional activity.

That along with the fact that I pursue this distraction in my home and don't have a proper ventilation system to evacuate potentially dangerous fumes away from my myself and family, I think that some prudent restraint is called for here.

I don't necessarily feel handicapped by my choices, I am pleased at the results I am getting, even if it perhaps takes a little longer and may be a step or two behind the really experienced and capable folks.

I have researched the use of Hydrochloric acid to free fossil diatoms. I am trying to decide if I can manage the risks and if the reward is worth it. Face Shield, Gloves, Apron, Respirator and everything done outdoors is the the base level of precautions as near as I can tell. That is a different level of involvement......

Rod

[zzffnn]

Rod,

I would choose sulfuric acid over hydrochloric acid, if you have to choose one. Of course, you don't have to choose either. Just saying, hydrochloric acid makes fume at many concentrations, while diluted sulfuric acid does not and can be equally effective. Just buy already diluted sulfuric acid to be safe.

[rnabholz]

Well, we had an extended family wedding out of town yesterday.

We travelled to Fort Dodge, Iowa for my cousin's wedding, the whole family gathered and had a wonderful day and evening celebrating.

This morning after breakfast, we prepared to pile in the car for the ride home, and I said " C'mon everybody, let's go get some slimy rocks!". They all just rolled their eyes.

I knew that the Des Moines River passed through Fort Dodge and as we traveled through town, I took notice of some nearby public boat ramps - always a great place to get quick and easy access to a river for sample collection. As "luck" would have it, my sample gathering tools just happened to be in the back of the car (Now how did they get in there?).

So we headed to the nearest one, I parked and jumped out, saying that I would just be a minute. To my surprise, my Wife, Son and Daughter decided to come along and watch. I grabbed a bucket and a cultivator (looks like this: http://www.homedepot.com/p/Ames-4-Tine- ... lsrc=aw.ds) that I use to reach into the water and retrieve rocks and sticks and headed down to the boat ramp.

Once there I quickly found a couple of good candidates. As I had what appeared to be a semi-curious crowd, I took the opportunity to show them what the diatom laden material I was hunting for looked like. It wasn't long before I had three more sets of eyes assisting in the search.

I found a couple of rocks that I consider to be typical, showing the relatively dark coloration which I have come to expect from our Iowa rivers, but did find one nice one that seemed to be much cleaner, for reasons I don't understand, so I added it to the bucket.

Just as were about ready to leave my son says he sees a beer can that one some fine member of society thought should live in the river, and it looks like it is covered with that "stuff". I instantly remembered the discussion we just had regarding non natural items and how they can yield clean samples, so we brought that can home with too. Here it is, it dried out on the way home.

DesMoinesRiverSampleCan.jpg (111.17 KiB) Viewed 295362 times

Once home, I cleaned the sample material from the rocks and cans. I made three different samples to better track the type of material from which they were gathered, The Usual Rocks, The Clean Rock and The Can.

Here they are 5 minutes after adding the Hydrogen Peroxide. Anybody want to guess which is which?

DesMoinesRiverSampleFlasks.jpg (118.77 KiB) Viewed 295362 times

From Left to Right, Clean Rock, Usual Rock and The Can.

Three batches cooking, more fun ahead!

[rnabholz]

Rod,

I would choose sulfuric acid over hydrochloric acid, if you have to choose one. Of course, you don't have to choose either. Just saying, hydrochloric acid makes fume at many concentrations, while diluted sulfuric acid does not and can be equally effective. Just buy already diluted sulfuric acid to be safe.

Thanks zz, I will look into that. It would seem to be a nice compropmise.

[zzffnn]

Just want to add that I cannot think of any hazard or explosion that can be produced by diluted sulfuric acid. But this is not true for diluated nitric acid (fuming, strong oxidant) or diluted hydrochloric acid (fuming). Short of kids swallowing it, of course.

[rnabholz]

Thanks zz.

Feel free to add any information that will keep me out of trouble.

Rod

[rnabholz]

My great kids surprised me a couple of weeks ago on my birthday with a GoPro Camera.

It is a cool gift, but I have to admit, since I don't do much Skydiving, Extreme Powder Skiing, or Motorcycle Jumping, I was not sure what I would do with it.

But today inspiration struck - Extreme Slide Ringing!!

My First Ever GoPro Video!!

[KurtM]

Hah - very interesting couple of posts there! Next test may have to be which beer cans yield classier diatom varieties: Bud Lite, Coors Silver Bullet, or Miller Lite? Any of them should be a richer step up from soda cans, anyway.

Seriously, I can hardly wait for the results, do keep us posted!

The slide ringing demonstration is perfectly lovely. Now you have one of only TWO videos showing how it's done on the entire Youtube/interwebz thingy. Can I have your autograph?

PS: Are we absolutely sure Fan caught that bit about fossil diatomite material? It's dirt, and different from the usual pond/river slime, y' know. Meanwhile, I understand Klaus Kemp does a lot of his processing in his garden ... I mean, back yard.

[zzffnn]

Kurt,

In terms of freeing diatoms from rock/dirt, I don't think those two acids (sullfuric vs hydrochloric acid) would work differently. I also doubt fresh diatoms makes a difference to those two strong acids.

If you are comparing vinegar (a weak acid) vs hydrochloric acid (a strong acid), then I would guess both would work for fresh diatoms, but only the strong acid would work to free diatom from dirt/rock.

Diluted sulfuric acid is just more stable and safer to handle.

[rnabholz]

Hah - very interesting couple of posts there! Next test may have to be which beer cans yield classier diatom varieties: Bud Lite, Coors Silver Bullet, or Miller Lite? Any of them should be a richer step up from soda cans, anyway.

Seriously, I can hardly wait for the results, do keep us posted!

The slide ringing demonstration is perfectly lovely. Now you have one of only TWO videos showing how it's done on the entire Youtube/interwebz thingy. Can I have your autograph?

PS: Are we absolutely sure Fan caught that bit about fossil diatomite material? It's dirt, and different from the usual pond/river slime, y' know. Meanwhile, I understand Klaus Kemp does a lot of his processing in his garden ... I mean, back yard.

Clearly the preferred beer for the best class of diatoms would be Miller High Life, which everyone knows is the "Champagne of Beers"

Funny you mention the dearth of slide ringing videos. When became interested in it I could only find the one video. I thought that was odd at the time.

So with all the pent up demand for new slide ringing videos, maybe I will break 20 views? WooHoo!

Good question about the acids effectiveness on the diatomite. HCL was the acid always mentioned in everything I could Google up.

[zzffnn]

This article mentions a few diatom cleaning reagents:

https://books.google.com/books?id=Va35M ... ic&f=false

It may be a comprise, if you want it safe and use diluted sulfuric acid.

That is why I pushed for incineration for fresh diatoms. It does not work for fossil though.

[KurtM]

I don't know beans about acids, and wouldn't know a reagent if it crept up and bit me on the ankle, so I must bow to Fan's superior knowledge of chemistry. But by jiminy, I can almost always tell dry dirt from wet slime, and have no idea if Fan can make such a distinction or not. Bet he can, just wanna be sure.

I also feel obliged to bow to Rod's advanced knowledge of cheap beer, uncalled for though the dig may be. (Dig, get it? Diatomite? It all ties together, I never leave loose ends.)

PS: I will be testing incineration any day now...

[zzffnn]

Guys,

I forgot to say that at the highest concentrations, those two acids do have differences, but as you said before, you do not want to go there. So we are talking low concentrations.

And if you boil the acids for long, they would change differently too, sulfuric acid will be more concentrated and fumes eventually, but hydrochloric acid turns into acid vapor and becomes less concentrated. Either can be pretty dangerous.

And Kurt made a good point about fresh vs fossil diatoms, as cleaning methods may differ there, depending on specific combinations. Like how incineration does not work with fossil.

Kurt, do it, burn it, go Kurt

[rnabholz]

Back to report on the results of the Des Moines River samples and I am sorry to say that the report is not a happy one.

Even after straining, the silt and mineral content in these samples is so high as to make them unusable. The samples from the rock are just awful. The sample from the can is cleaner, but contains very few diatoms, and the ones that present are small and of a very limited variety.

It is a disappointment, especially as getting another sample is not easy due to the distance involved.

Onward and Upward.

[rnabholz]

I thought some of you might be interested in a book that I picked up recently.

Diatoms of North America by William C. Vinyard.

A paperback of 120 pages that provide an excellent reference for identifying common diatoms. It would not be considered a comprehensive guide, but I have found it very helpful in getting me started on ID'ing forms that I have come across. The book contains illustrations of 180 forms as well as detailed descriptions of the features and identifying characteristics of each family.

It is available on Amazon for around $12 or so. I would refer you to the reviews of the book there for more details about the content and utility.

In my estimation it is well worth the money and a handy reference.

DONA Cover.jpg (93.37 KiB) Viewed 295290 times

DONA Illustrations.jpg (99.34 KiB) Viewed 295290 times

DONA Spread.jpg (76.18 KiB) Viewed 295290 times