JรRNBRรK

Iron films, acid mine drainage, natural science, and more.

Jรกrnbrรกk?

Jรกrnbrรกk is an icelandic term that refers to a natural biogeochemical phenomenon also known as a "floating iron-rich film" or just an "iron film".

What is an iron film?

Iron films are a distinctive feature common to wetlands, seeps, and still areas of rivers and lakes. Though commonly mistaken for gasoline or oil pollution due to their coloration, iron films are naturally occurring, and are largely thought to be a consequence of iron-oxidizing microbes such as Leptothrix discophora. Also known as floating iron, iron-bearing films, Schwimmeisen (German), or Jรกrnbrรกk (Icelandic), these films are all at once ubiquitous (found all over the world), visually striking, and potentially valuable as metal indicators or as a method of mining wastewater remediation. Despite this, these films and the bacteria associated with their formation are underrepresented in the literature, and often overlooked and misunderstood by the public.

An image of a particularly vibrant iron film.

Iron film or gasoline?

How can you be sure that you've encountered an iron film, and not an oil spill? There are a few indicators. One common method is to take a stick or other object and touch the film. An iron film is made out of solid mineral precipitants and will shatter into platelets. Gasoline is a liquid, and will swirl around the stick instead - not break.

While handy, this trick is not a way to definitively conclude if a surface water film is natural or pollution. A number of solid substances can also be pollutants. Another indication of natural iron film formation is the appearance of rusty-colored gooey masses of flocculate under the water. These iron-rich flocculate masses indicate the presence of iron-oxidizing bacteria. Another feature of iron films is that they form very slowly on water surfaces and can take hours to days to build up. Iron films don't bubble to the surface upon disturbance, but pollutants can.

Lastly, it is worth mentioning that iron films and iron bacteria, while natural, can commonly occur in areas that are heavily polluted such as acid mine drainage. While these films may not necessarily be oil pollution, extra iron in the environment can be a sign of acid mine drainage conditions. Some microbes can accelerate acid mine drainage conditions, while others might help remediate mining pollution. Biology yet lives outside of the paradigm of human binaries!

An image of iron-rich flocculate. Note the rusty iron-orange color and the cloudy-like fluffy appearance. You often see this in tandem with iron films, but not always.

Where do iron films form?

Iron films are thought to be ubiquitous, meaning that they form everywhere. Here is a map featuring locations at which I have witnessed iron films!

I think I've found an iron film!

Have you encountered an iron film near you? I invite you to photograph the occurance and upload an entry to a site like iNaturalist! You will notice that other users commonly record iron-film observations as instances of Leptothrix discophora or just Leptothrix. This bacteria is definitely the poster-child for iron films. You can check out some of my observations below!


Do you have any comments, questions, or concerns about the content on this website? You can reach out to me by email (see the "about" page) or feel free to comment below. Thank you for visiting!

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Meet the Webmaster

My name is Roger Ort, and I am the sole webmaster of jarnbrak.net. I'm currently a graduate student in the Penn State Department of Geosciences, where I am pursuing a dual degree PhD in Geoscience and Biogeochemistry. I graduated from Oberlin College in 2021, where I recieved a BA in Biology. I currently research biological methods of remediating acid mine drainage and mining waste.

My interests (and, as such, content you will likely find on this blog) include iron films (of course); acid mine drainage (AMD) and other forms of mining pollution with a focus on remedition; the phenomenon of optical thin-film interference; microbial life, especially iron-oxidizing bacteria, but also algae (and others); the care and keeping of ecosystem jars.

Ultimately, I made this site to share my passion for iron films with others, but also to communicate with others about natural science topics that I find interesting, as well as share images and records of my ecosphere jars and field excursions.

Contact Me

If you have any questions, comments, corrections, inquiries, complaints (hopefully not!), burning philosophical quandries, or images of iron-films or acid mine drainage near you that you'd like to share (please do!), contact me at rco5102 at psu dot edu (censored to avoid spam - replace the at with "@" and dot with ".")

Links

This section includes other places you can find me online, such as my social media accounts ๐Ÿ“Œ, articles I've written, authored, or assisted with ๐Ÿ“„, and other pages or articles I've shown up on ๐Ÿ“ฐ.

๐Ÿ“Œ Twitter @jarnbrak
๐Ÿ“Œ Tumblr @jarnbrak
๐Ÿ“Œ iNaturalist @jarnbrak
๐Ÿ“ฐ Art + Science at Trout Lake Station, Wisconsin
๐Ÿ“„ Study-abroad in Japan under COVID-19
๐Ÿ“„ Environmental predictors of electroactive bacterioplankton in small boreal lakes

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Link to Us

If you want to link to us, you can use this button if you're so inclined. We are reachable at jarnbrak.net or at sites.psu.edu/jarnbrak.

Creative Commons Liscence

Images, text, and content on this website is shared under a CC BY-NC creative commons liscence. This license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format for noncommercial purposes only, and only so long as attribution is given to the creator.

To attribute to us, you may link back to the site, mention the site by name (Jarnbrak.net), or attribute the content to the webmaster (Roger Ort, Penn State University) - or any combination of the three. This means you are free to share our photos and content on social media, blogs, or your own site. In fact, if you want to share photos and facts about iron films, you are wholly encouraged to do so! Thank you.

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Ecospheres & Winogradsky Columns

I find great satisfaction in the care and keeping of ecosphere jars and Winogradsky columns - which, accordingly, require a minimal amount of care and keeping by design.

While I don't particularly find a lot of success in keeping plants (they tend to die, so I am often hesitant to procure new ones lest I accidentally end their lives). In contrast, it is rather impossible to destroy life in these little self-contained "ecosystems". I of course take care to not include macroinvertabrates besides snails in my various tanks and jars, though, but zooplankton and snails are abound in most of them!

This page will grow to include details about my sealed and unsealed ecosphere jars, my open algae tanks, my Winogradsky columns, and any terrariums and plants. I am always eager to innoculate new jars with water and dirt samples from new locations.

My beautiful windowsill, which brings me great happiness to look upon every morning, afternoon, and evening!

Winogradsky Columns

Winogradsky columns contain a mix of mud and water and are meant to offer a cut-away view of microbial community development that we normally don't get to see.

๐Ÿ“ Hawley Brook, CT
๐Ÿ“… August 2021

This Winogradsky column is my oldest and my personal favorite. I collected the sediment and water from a (beloved, by me at least) acid rock drainage contaminated effluence near Hawley Brook, CT, where the iron-heavy sediment is a rich orange color.
To this day it is still actively changing in apperance, which I find fascinating to watch. I particularly enjoy watching the development of the iridescent thin film coating the bottle sides, which looks like holographic cellophane.

Image coming soon.

๐Ÿ“ Buckingham Seep, PA
๐Ÿ“… September 2022

The final project of my Fall 2022 microbiology course was a short paper about the construction and monitoring of a set of nearly identical Winogradsky columns, one exposed to light conditions and the other exposed to dark conditions. Innocula was obtained from Pennsylvanian acid mine drainage.

๐Ÿ“ Beaver Run Borehole, PA
๐Ÿ“… June 2022

A circumneutral mine drainage effluence bubbling up from a flooded mine vent, featuring an interesting microbiome. The borehole is encrusted with black, green, white, purple, and orange masses, and white "sulfur streamers" float in the effluence downstream.

๐Ÿ“ Roaring Brook, CT
๐Ÿ“… August 2021

Made with mud from my childhood brook. Very smelly, likely due to having a high amount of rotting organic matter (mud). Hard to see due to the dark coloration, but filled with purple and green sulfur bacteria.

Ecosphere Jars

Sealed ecospheres that aren't managed, maintained, or interfered with after their creation date.

๐Ÿ“ Roaring Brook, CT
๐Ÿ“… August 2022

A repeat of my previous Wino column using more live plant matter, sand, and water. This one has much more algae which has coated the inside surface in a dense mat.

๐Ÿ“ Farmington River, CT
๐Ÿ“… August 2022

Contains live plant matter and river rocks from the Farmington River, another favorite childhood spot of mine. Less algae due to the presence of what I think is a (probably invasive, unfortunately) water milfoil plant.

๐Ÿ“ Great Wass Island, ME
๐Ÿ“… August 2022

A salt-water column containing beach rock, shells, and purple sulfur bacteria innocula from a hike on Great Wass Island. Was seemingly barren for months until it all of a sudden filled up with beautiful curly leafy-looking "seaweed"! Has a lot of purple sulfur bacteria.

๐Ÿ“ Sugarloaf Key, FL
March 2022

Constructed from sand, silt,and washed-up dead coral fragments from beachcombing. Saltwater, but lacks purple sulfur bacteria. Very uneventful.

๐Ÿ“ Green Lake, NY
๐Ÿ“… October 2021

Silt and water from Green Lake, NY, famous for its thrombolite formations. Contains some algae and iron bacteria, but also has an interesting biofilm-like matrix of some kind of substance distributed throughout the neck of the bottle.

๐Ÿ“ Ore Pond, PA
๐Ÿ“… October 2021

Sediment and water from an abandoned flooded mining pit in Pennsylvania, also a very uneventful column with a simple green lawn of filamentous-looking photosynthetic growths.

๐Ÿ“ Appledore Island, ME
๐Ÿ“… August 2022

Sediment and water from Appledore Island, near Central Pond.

Terrariums

Sealed and unsealed terrariums where I keep non-aquatic plants and/or mosses.

๐Ÿ“ Cutler Coast, ME
๐Ÿ“… August 2022

Mud and some sphagnum moss from near Cutler coast in Maine. I constructed this little jar thinking that the moss would quickly die, but months later it appears to still be going strong.

Aquatic Tanks

These are my open-air aquatic tanks which contain biota from various sources.

The Snail Tank
Has the most snails, requiring water changes.

The Rocky Tank
Contains few snails and little algae. Has a rocky substrate and some zooplankton (namely daphnia).

The Big One
My largest tank, containing material from a nearpy Pennsylvania stream as well as the Penn State alumni pond.

The Duckweed Tank
A shallow circular tank that I use to grow duckweed, algae, and provide a consistant source of water for my spider plant.

Slide Collection

While I have been seeking out and photographing iron films since 2018, I realized in November of 2020 that iron films could also be quite easily skimmed off the surface of a body of water, right onto a glass microscope slide. Not only that, but the colors and patterns can be mostly preserved if you're careful. It's hard to photograph the thin-film effects of the iron films when they're on a slide, unfortunately, but the thin-film optics are intact and can be viewed in person. Here are some pictures of slides in my slide collection.

I hope to update this page to eventually include my entire collection - but I have about a hundred of these things, so it might be a while!

Site Articles

Articles that I've written on a variety of topics. Will contain longer-form and more in depth content. More will be added soon!

Iron is not usually associated with having a "rainbow" coloration. Rust, for example, is orange, and the metal itself is a shiny grey. Why, then, can iron films seem to form every color in the rainbow?

The answer is that iron films exhibit something called structural coloration. Strucural colors are colors that result from light interacting with microscopically small surface structures on an object. This is different from the green, red, and yellow that we see in most leafy plants, or the colorful dyes that we use to color clothing. These colors are derived from pigments, molecules that absorb and reflect different wavelengths.

Examples of structural color are actually all around you! The vibrant blue color of blue jay feathers is one example. Blue is a famously rare pigment in nature and is expensive to produce. Instead of investing valuable time and energy in creating a blue pigment in its feathers, blue jays have evolved to form nanostructures in their feathers that warp light in order to produce a blue structural color. Some other examples of structural color can be seen in peacocks, grackles, butterflies, seashells (nacre), some insects, soap bubbles, and gasoline!

Iron films, soap bubbles, and gasoline actually all get their coloration from a form of structural color called thin film interference. Iron films are a type of thin film, a term which refers to a layer of material that is only nanometers in thickness. These thin layers are around 2000 times thinner than a human hair, and can be even thinner!

At a scale this small, thin films are actually capable of messing with light. When a ray of sunlight hits a film, it both reflects off the surface of the film and refracts into the film. The ray of light which refracted into the film then reflects again, this time off the underside of the film. It then travels back up, hits the top of the film, and refracts back into the air.

However, because the film is so thin, this refracted ray ends up being close enough to the initial reflected ray to cause the rays to interfere with each other. Depending on the speed of the rays and the distance they have to travel in the film (e.g. the thickness of the film) this interference results in the human eye seeing a vibrant color on the thin film spectrum.

This image was created by Nicoguaro on Wikipedia.

So why do we see a plethora of rainbow-like colors when we see iron films, as opposed to just one? The answer is that iron films vary in thickness. These changes in thickness in a film are so microscopically small that human eyes cannot percieve them - it's even hard to see under a microscope! However, small alterations in the thickness of a thin film results in the human eye perciving a wildly different color. That is why we see patches, patterns, and spots of rainbow-like color across iron films.

Is thin film interference why iron films and gasoline spills look so similar? The answer is yes! Iron films are a type of solid precipitant containing iron-rich minerals and organic matter that form on water surfaces. In contrast, gasoline is a clear liquid made up of hydrocarbon molecules. Despite being composed of very difference substances, both gasoline and iron films get their coloration from thin film interference instead of any type of pigmentation. Their composition doesn't play a significant role in the color that the human eye sees - instead, the thickness is what controls the colors. If you study gasoline spills and iron films very closely, you can actually notice a lot of differences between the two in terms of patterning, what colors are common to see, and how they form - the only similarity is that they form thin films on water surfaces.

A thin film interference spectrum, screenshotted from a demonstration by Peter Canfield.

Are iron films "rainbow"? The answer is, surprisingly, technically no! Iron films exhibit colors on the thin film spectrum, which includes many but not all of the colors of spectral light. Notably, the thin film spectrum is lacking colors like red. However, it includes colors such as bright pink which is not a part of the rainbow!

Another difference between the thin film spectrum and a rainbow is the order in which the hues proceed. Nearly everyone is familiar with ROYGBIV - red, orange, yellow, green, blue, indigo, and violet. Most are likely less familiar with SGMVBYPBGYPGPGP... or silver, gold, magenta, violet, blue, yellow, etc... you get the idea.

I am a biogeochemist, and not a physicist, so the optics behind thin film interference, diffraction, and colors isn't my wheelhouse. I encourage you to research the topic more if you are interested!