Tag: immersion

September Storms in on the River

A line of canoes float past limestone bluffs in the midst of a thunderstorm.

The middle school class has been reading The Tempest for language arts this semester. However, I had not quite realized that it was a presentiment of for our outdoor education canoeing trip. And not metaphorically — the group worked amazingly well together — but there really was a massive storm while we were out paddling on the Current River.

Weather map from Wednesday, September 26th, 2012.

On Wednesday morning, two hours before dawn, a cold front heading south from Canada met a warm front coming north out of the Gulf. They met and stalled, pushing waves of clouds and thunderstorms over us from the west.

The first wave hit while we were in our tents; the second during breakfast. One student recounted that his highest point of the trip was when he tasted his first pancake that morning. His lowest point was when the pancake was promptly soaked with rain.

The third wave met us while we were in our canoes.

Searing lightning, flashing across the ridges of the valley. Blinding white. Immediate thunder, roaring straight through the ears, reaching in, taking the breath, grabbing at the soul. Drenching rain — cold and hard — a deluge. One of our guides described it, afterwards, as a religious experience. I think I know what she meant.

Our guide (Ronnie) takes refuge under an overhang during the height of the downpour.

But the kids were awesome. Drenched, cold, and scared they paddled on. I was with a small group that was bringing up the rear. We were far enough behind that, for a long time, I could not tell how the students in the lead were responding. Especially when, at the height of the downpour, the lead group went around a bend in the river and out of our line of sight.

And there was a loud cheer.

I knew they were with our lead guide (Leah), whose skill and competence had already been demonstrated earlier in the day when one of the canoes had flipped. Yet, one always worries about how kids will react in stressful situations. Following the current around a gravel eyot, however, I heard a loud cheer. There was the line of canoes, pulled over waiting for us. There were the students, soaked and perhaps a little bit relieved, but with no panic in the cacophony of voices.

When everyone had caught up, we continued on. Eventually, we hit a landing and called an end to the canoeing. Although the rain had stopped it was still cold. So, a few students decided that since the river water was so cold, if they waited in the water, when they came out they’d feel warm. “I’m willing to deceive my body,” they said.

Waiting for the bus.

While we waited for the bus, we talked a little about what we’d been through. Despite the stress — or perhaps because of — there was lots of laughter and a growing sense of camaraderie. I took the chance to highlight some of the quieter voices, those students who tend not to complain or be too excitable, and who took the time to appreciate the beauty and uniqueness of what they’d been through.

While I would not have planned it that way, the storm, our tempest, forged bonds of common experience that will resonate with this group for years to come.

The first raindrops create tiny, concentric, waves that spread out and merge gently over space and time.

Notes

Infra-red satellite imagery from Wednesday, September 26th, 2012 shows the waves of thunderstorms passing over southern Missouri (yellow dot) very well.

The individual images come from NOAA’s GEOS archive: http://www.goes-arch.noaa.gov/

(From our Eminence Immersion)

How to do Research on the Internet: A Lesson

This morning I did a little presentation with the middle school on how to do research on the internet, and we actually had a very good discussion. I focused on two key things: assessing credibility and writing citations (giving credit).

Credibility

[Henry] Hudson’s main goal as an explorer was to find a northern passage to the Orient. … He started his journey in May of 1607 and returned in September of the same year when his route was blocked by the Great Barrier Reef.

— All About Explorers (accessed Feb. 2012): Henry Hudson

I started by having the students to look up some explorers. If you prefix an explorer’s name with “all about explorers” (e.g. “all about explorers Christopher Columbus) the first link on google leads to the right website.

They were supposed to read the page and recorded three facts that they found interesting, but, in doing so, it pretty quickly becomes apparent that the information might not be very reliable; Columbus did not, after all, have to rely on infomercials to build support for his expedition.

The All About Explorers website was created by a group of teachers to be a tool for teaching about how to do research on the internet.

Having them see the site come up on google is, I think, better than sending them directly to the url. Google is usually their first recourse for researching anything, so it’s nice to see that google does not give information about credibility.

The discussion that ensued ranged pretty widely, but a key question that kept recurring was: how do you judge the credibility of a website. We talked a little bit about the possible biases of commercial .com and .net websites, and about the fact that .org’s may well also have their own biases, since it does not require any credentials to set one up (see montessorimuddle.org for example). On the other hand, while .gov and .edu domains (as well as most U.S. state and other country websites) are restricted to governments and colleges, that improves their credibility, but, in itself, is no guarantee of accuracy or being unbiased.

So much of assessing websites’ credibility comes from experience, which students just don’t have much of yet, so I recommended that checking with teachers and adults might be a good bet. Confirming data from multiple sources also helps, but you have to be careful, since so many websites now use Wikipedia as a source (or even reprint things directly from Wikipedia) that any errors in a Wikipedia page can spread far and wide pretty fast.

We did not get into how to use Wikipedia well (go for the sources at the bottom of the page), but we’ll get to that later.

Citing

For the second part of the lesson, I had them look up the same explorers they’d searched on the All About Explorers website. They had free range to search anywhere they wanted, but not only did they have to now collect facts but were to also find a good picture.

I’d wanted the pictures so we could talk about copyright and getting permissions to use media, but we did not get that far.

While they were satisfyingly more skeptical about where they got their information from, they were quite happy to give me the facts they’d found without attribution.

So I took the chance to talk about citing sources: to give credit where it is due; to avoid even the appearance of plagiarism; to give your reader an idea of how credible your sources are (and by extension how credible you are); and to let you readers know how up-to-date your information is.

An example of a citation for a website.

Conclusion

For the next week or so the middle and high school are on an interim. This is our writing interim, so they’ll be working on research projects (including how to do research) and creating publications (I’m in charge of the science journal).

Since more and more research is going online, hopefully this was a good primer to get students started.

Coal Seam

Escavator digs out the coal.

Although it was high in sulfur, the quarry company mined the thin coal seam that cut across the limestone quarry/landfill.

The water cycle, at the quarry.

The layer of coal is pretty impervious to water, so it blocks vertical infiltration of water, which forces the water to the surface as springs.

At the surface, when the water is exposed to oxygen in the atmosphere, dissolved iron precipitates to produce a red mineral that stains the quarry walls.

The iron gets into the water when pyrite crystals (FeS2) in the coal dissolves. While the iron precipitates, the sulfur remains in the water, making it more acidic. Dealing with the acid can be a huge problem in large coal and metal mines.

The pool of water that collects at the base of the quarry, is probably fairly acidic.

Not all the pyrite is dissolved however, and since this particular coal seam has a lot of pyrite, it is not economical to burn since the burnt sulfur (as sulfur dioxide gas) would have to be captured — otherwise it produces acid rain.

The rich black coal seam sits on top of blocky limestone rock. Above the limestone is a red, weathered soil.

The Water Cycle … at the Quarry

The water cycle, at the quarry.

The water cycle is intricately tied to all the other topics that came up on our visit to the quarry/landfill. For some things, the tie to water is direct and inextricable.

  • It’s groundwater that dissolves the pyrite in the coal seam and then precipitates an orange iron stain on the quarry cliffs.
  • Rainwater seeping into the landfill leaches out chemicals that have to be prevented from getting into the groundwater, rivers or lakes.
  • Gases like hydrogen sulfide can react with water (and oxygen) in the air to produce acid rain. Not to mention that water is needed for the decaying processes that produce the hydrogen sulfide, and other landfill gases like methane, to begin with.

For other things the link to water is not necessarily so obvious:

  • The sediment that was compressed into the limestone that is being quarried, was formed beneath the shallow seas that once covered this region in the geologic past. Limestone is also dissolved by rainwater to create caverns, underground rivers and spaces for geodes.
  • Methane gas not only requires water for it to be released via decomposition of garbage, but also produces carbon dioxide when burned. Carbon dioxide is a greenhouse gas, so it affects the global temperature and contributes to the melting glaciers, rising sea levels and changes in climatic patterns such as the amount of rain we’re going to receive in the midwest.

The water cycle picture starts simply, but gets complicated very quickly.

A bigger, fuller picture of the water cycle as it interacts with the quarry.

Methane from Landfills: The Uses Of

Methane in a landfill. It's produced by decomposing organic material, is extracted via wells, and is then burned to produce heat (for a school and a set of greenhouses) and electricity (soon anyway).

Decomposing waste in landfills produces quite a lot of methane gas (CH4). Perhaps better known as natural gas, methane is one of the simplest hydrocarbons, and a serious atmospheric pollutant (it’s a powerful greenhouse gas). In the past the methane produced was either released into the atmosphere or just burned off.

Greenhouses that are warmed by methane produced by the landfill. It's a cheap, close source of energy.

I remember seeing the offshore oil rigs burning natural gas all night long — multiple miniature sunrises on the horizon — in the days before the oil companies realized they could capture the gas and sell it or burn it to produce energy. The landfill companies have realized the same thing. So now, wells pockmark modern landfills and the methane is captured and used.

Looking down the slope of the landfill to see the Pattonville High School, which uses natural gas from the landfill for heating.

First, of course, the hydrogen sulfide gas (H2S), is separated from the methane — H2S produces acid rain, so it’s emissions are limited by the EPA — then, the gas from the landfill we visited, is piped to:

  • greenhouses, where it’s burnt to produce heat;
  • the Pattonville High School, which is right next to the landfill and burns the gas for heating;
  • and (soon) to a electricity generating power plant that will burn the gas to produce heat which will boil the water that will produce the steam that will turn the turbines that will generate the electricity.
Electric power plant -- still under construction -- that's fueled by methane from the landfill.

You may have noticed the common theme of all these uses of natural gas: it has to be burned to be useful. The combustion reaction is:

CH4 (g) + 2 O2 (g) —-> CO2 (g) + 2 H2O (g)

which produces carbon dioxide (CO2) that is also a greenhouse gas, but is, at least, not nearly as powerful at greenhouse warming as is methane.

Iron Stained Walls

The limestone walls of the quarry were stained red with iron precipitate.

The cliffs of the quarry were stained red. Blood, seeping out from between the bedding planes between layers of rocks, might have left similar traces down the sides of the near-vertical cliffs’ faces. But these stains are actually made of iron.

Rain falling on the land above the quarry, seeps into the ground. There it moves downward through the soil, leaching out some of the minerals there, but going ever downward. Downward until it meets a layer of soil or rock that it can’t get through. Clay layers are pretty impermeable, though in this case it’s a layer of coal. The water can’t move through the near-horizontal coal seam very fast, so instead it moves sideways across, and eventually seeps out onto the cliff face.

The red on the walls of the cliffs are an oxidised iron precipitate (rust). The iron most likely was dissolved out of the pyrite in the coal seams.

The seeping water still has those minerals it dissolved in the soil. It also has more dissolved minerals from the coal it encountered too. Coal forms in swamps when trees and other plants fall into the waters and are buried before they can completely decompose. Decomposition is slow in stagnant swampy waters because most of the insects and microorganisms that do the decomposing usually need oxygen to help them with their work. Stagnant water does not circulate air very well and what little oxygen gets to the bottom of the swamp-water is used up pretty fast. You could say that conditions at the bottom of the swamp are anoxic (without oxygen), or reducing.

Coal formation. Image from the National Energy Education Development Project.
A shiny pyrite crystal in a lump of coal (happy holidays). Image via USGS.

Iron in air will rust as it reacts with water and oxygen — rust is the red mineral hematite (Fe2O3) that you see on the walls of the quarry. Iron in a reducing environment, on the other hand, will form minerals like pyrite (FeS2). According to our guide, the thin coal seam in the quarry has a fair bit of pyrite. In fact, because of the pyrite, the coal has too much sulfur for it to be economical to burn. Like the landfill gas, hydrogen sulfide, burned sulfur turns into sulfur dioxide, which reacts with water droplets in the air to create acid rain so sulfur emissions are regulated.

The water that seeps along and through the coal seam will dissolve some of the pyrite, putting iron into solution. However, the iron will only stay dissolved as long as the water remains anoxic. As soon as the high-iron water is exposed to air, the iron will react with oxygen to create rust. Thus the long stains of rust on the cliff walls show where the water emerges from underground and drips down the cliff face.

Diagram showing the coal seam, and the seeping water that creates the iron (rust) staining.

Iron precipitate in other environments

On our Natchez Trace hike we found it quite easy to stick fingers into the red precipitate at the bottom of the stream.

We’ve seen the precipitation of iron (rust) as a result of changes in redox (oxidizing vs reducing) conditions before: on the sandbar on Deer Island in the Gulf of Mexico; in the slow streams along the Natchez Trace Park‘s hiking trails in Tennessee. Iron precipitation is an extremely common process in natural environments, and it’s easily noticeable. Just look for the red.

The rich black of decaying organic matter, sits just beneath the rusty-orange surface sediment. The red is from hematite (rust) and shows that the surface is oxidizing, while the black shows that just a few centimeters beneath the surface, there is no oxygen to decompose the organic matter (a reducing environment). This image was taken on Deer Island on the Gulf Coast.

Landfills: Dealing with the Smell (H2S)

Hydrogen Sulfide:
H2S

Diagram of the hydrogen sulfide system in a landfill.

Although it makes up less than 1% of the gases produced by landfills, hydrogen sulfide (H2S) is the major reason landfills smell as bad as they do. H2S is produced by decomposition in the landfill, and if it’s not captured it not only produces a terrible, rotten-egg smell, but also produces acid rain, and, in high enough concentrations, it can be harmful to your health (OSHA, 2005; Ohio Dept. Health, 2010).

Decomposition

A wall partially covered with drywall. Image via FEMA via Wikimedia Commons (Nauman, 2007).

Some hydrogen sulfide is produced when organic matter decays, but for big landfills like the one we visited, construction materials, especially gypsum wallboard (drywall), are probably the biggest source.

Gypsum is a calcium sulphate mineral, that’s made into sheets of drywall that are used cover the walls in most houses because it’s easy to work with and retards fire. The U.S. used 17 million tons of gypsum for drywall in 2010 according to the USGS’s Mineral Commodity Summary (USGS, 2011 (pdf)).

Gypsum:

CaSO4•2(H2O)

As you can see from the chemical formula, each gypsum molecule has two water molecules attached. In a fire, the heat required to evaporate the water keeps the temperature of the walls down to only 100 degrees Celcius until the water has evaporated out of the gypsum board.

A number of landfills have banned drywall because it produces so much hydrogen sulfide, but the one we visited still takes it. It’s big enough that they capture the landfill gasses, including the hydrogen sulfide, and then separate it from the other, more useful gasses, like methane, which can be burned to produce heat energy. H2S can also be burned, but they you end up contributing to acid rain.

H2S and Acid Rain

When hydrogen sulfide reacts with oxygen in the atmosphere it produces sulfur dioxide.

2 H2S (g) + 3 O2 (g) —-> 2 SO2 (g) + 2 H2O (g)

Sulfur dioxide, in turn, reacts with water droplets in clouds to create sulfuric acid.

SO2 (g) + H2O (g) —-> H2SO4 (aq)

Acid rain accelerates the dissolution of statues. (Image by Daniele Muscetta)

When those droplets eventually coalesce into raindrops, they will be what we call acid rain.

Acid rain damages ecosystems and dissolves statues. It used to be a major problem in the midwestern and eastern United States, but in 1995 the EPA started a cap and trade program for sulfur dioxide emissions (remember sulfur dioxide is produced by burning hydrogen sulfide) that has made a huge difference.

The head (top) of a well (vertical metal pipe) that captures the gas from inside the landfill.

Capturing H2S

Probably because of the EPA’s restrictions, the landfill company pipes all the gases it collects through scrubbers to extract the hydrogen sulfide. There are a few ways to capture H2S, they all involve running the gas through a tank of some sort of scavenging system that holds a chemical that will react with hydrogen sulfide and not the other landfill gases. At the landfill we visited the remaining landfill gas, which consisted of mostly methane, was used for its energy.