Archive for 'Unit 4-Biogeochemical Cycles'
As we approach the final day before the AP exam, have you reviewed the nutrient cycles? Knowledge of these cycles is critical-they tie everything together. In the fall we learned primary reservoirs, key chemical reactions, and anthropogenic impacts. I also had each of you write a creative short-story of a cycle. Here is a good one by MiriamA:
To be consistent is Carl’s game. His friends even go as far as to call him a connoisseur of consistency. But even the existence of a consistent Carbon molecule can be quite stressful. Sometimes, the mundane routine of Carl’s daily reality was overpowering: wake up, realize he’s stuck in a rock, think about eating breakfast, but realize he’s in a rock, take a nap, consider breaking out of his rock prison, and then realizing he is stuck. In a rock. Repeat for millennia.
Carl’s predicament made him pretty bored. His life seemed doomed to be forever consistent, when all of a sudden, Carl realized his rock was on top. Way on top: Consistent Carl was king of the lithosphere. Through weathering, Carl’s little piece of sedimentary rock was exposed and divided. Centuries went by; he was trod on by wooly mammoths, rained on incessantly, rolled by the wind down hills, and pushed back up them by construction trucks as gravel. And just when our friend Carl could no longer take the inconsistency of his new life, the greatest change yet struck him: Lichen was Carl’s new immediate neighbor. Carl’s rock was broken down by lichen into the soil. Carl was excited to be returned to the soil once more, but to his surprise…he was RESPIRATED.
As Carl considered changing his vacation response on his email back to his classic signature of “-You’re Favorite Boring Molecule”, Carl had yet another wake up call. His neighbor Lichen (fondly known as DJ Breakdown) had used energy to break him down, and had respired in the process, releasing Carl airborne as CO2 into the atmosphere.
Feeling like a new molecule, Carl was in ‘CO2 Tattoo Parlor’, inking in his newfound freedom, when he felt himself being pulled eastward over a body of water. He was newly surrounded by other, unfamiliar, yet similarly liberated CO2 molecules (some with ‘Stairway to Heaven’) inked across their covalent bonds), bumping about in the atmosphere. Back in his consistent days, Carl had attended school with perfect attendance, and thus new that the amount of CO2 in the air pocket he was in was greater than that in water, and that he would soon be diffused below the water’s surface. As he mentally prepared for the big plunge, Carl was yet again surprised when he was intercepted by a surface-dwelling aquatic organism and used for photosynthesis.
When the surface-dweller decayed, Carl was yet again released by the help of decomposers. He floated down, down, down, past his previously airborne friends who had arrived at the same place he had through diffusion. He bumped in H20, and formed Carbonic Acid. Carl, who had never been part of such a demanding relationship before, could barely recognize himself. The change kept going when he was transformed into bicarbonate, and then met Calcium. Before Carl knew it, he was part of Calcium Carbonate; planted on the bottom of the ocean floor as part of a coral reef. Carl had come a long way since his rock days, and was here to stay. He bought a new desk, got a haircut, and moved in for a while.
But what happened to some of Carl’s tattooed friends? Some of them were diffused, some of them decayed, but some were used in photosynthesis in photosynthetic organisms on the surface of the water. When that producer was eaten, the consumer respired to use glucose, and released the CO2 back into the atmosphere. They were airborne once more (‘Free Bird’ was added to the covalent bonds), but that did not last long. The CO2 was used once again for photosynthesis on the shore, helping a tree to grow. Years and years passed, and Carl’s friends went with the decaying tree to the soil, where they were broken into smaller and smaller pieces. And like Carl’s favorite book, Life Swap, Carl’s friends settled down over the millennia for a nice consistent life as sedimentary rock.
A little summary of pathways also by MiriamA:
Released to atmosphere
Used by plants for photosynthesis
Plants eaten by consumers
Higher level consumers eat those consumers and respire, returning to atmosphere
Co2 travels on over to a large body of water
Diffuses into the ocean (high to low)
Used by surface dwelling creatures, respire, returned to atmosphere
Where it is used by plants for photosynthesis
Turn into sedimentary rock again………
Diffused Co2 meets up with H20, makes carbonic acid, which turns into bicarbonate
Bicarbonate meets with calcium to make calcium bicarbonate
Precipitates, becomes coral!!
Degraded coral is impacted together, turns into sedimentary rock
So, do you remember the steps of the carbon cycle? Do you remember the formulas for these forms of carbon? Do you recall all the ways humans alter this cycle?
Hey, I don’t understand the differences between chemical weathering and mechanical weathering. Are things like ice wedging types of mechanical weathering? If so, then what is chemical weathering? And I know that the main reservoir of phosphorus is in rock and that’s how it is released, but does the “weathering” process release phosphorus? Thanks.
This last chapter, we really started to get an idea of how biogeochemical cycles work and can “malfunction.” Here are a few interesting current events on the topic if you want to learn more:
Nitrogen Cycle: Whales Help Fertilize Ocean With Floating Dung
Phosphorus Cycle: Manure, Fertilizer Part Of Chesapeake’s Problem
Carbon Cycle: Methane Causes Vicious Cycle In Global Warming
and..while we did not focus on the sulfur cycle, this is a good story about the role of sulfur dioxide in our atmosphere:
Sulfur Cycle: With Lave, Volcano Spews Chemicals to Cool Earth
unfortunately, sulfur dioxide combines with water to form acid rain too…more on this in the spring.
Posted: November 14th, 2010 under Mr. W, On My Mind Post, Unit 4-Biogeochemical Cycles.
Tags: atmosphere, carbon, current events, cycles, eutrophication, fertilizer, nitrogen, phosphorus, sulfur, warming gases
How does carbon escape from sedimentary rock besides volcanic eruption? And the diagram in our books shows an arrow from “soil and soil biota” that connects with respiration, I am confused on what this means?
I’m looking through my notes, and I can’t really tell the difference between an aquifer, the water table, and groundwater. It seems like they’re all really similar to me. What’s the difference??
I’m confused about what happens when plates diverge. I know lava pushed them apart, but how is that not a volcano? Does it slowly seep up? If so, wouldn’t the lava get pushed back down by the first layer of crust that cooled?
I understand that the Earth is made up of a bunch of techtonic plates that float on top of magma below the surface. But what I don’t understand is what exactly subduction does. I know that one plate slides underneath another, but what is happening with the magma? Is the sliding of the plate underneath the other forcing the magma to the surface? Or does there just happen to be magma near the surface where the two plates are colliding/sliding underneath the other?
I think I understand how aquifers work, and how they contain groundwater. But is the aquifer/groundwater the lithospheric stage for the water cycle? I know how water travels between the other three spheres but I am not sure how it can really be in the lithosphere and in rock. Thanks for the help!
(is it too early to do a reflection post? I’m afraid I’ll forget to ask tomorrow.)
I understand the carbon cycle from: atmospheric CO2, traveling through the biome (producers, consumers, detritivores, respiration) through diffusion INTO the ocean, and the formation of coral reefs/calcium carbonate, but I don’t understand what the last step in the cycle is. The CO2 has to return to the atmosphere, right? How does the CO2 exit the coral that’s been formed/deep ocean, and return to the atmosphere? Or is the step where calcium carbonate is formed a ‘branch’ off the cycle, and the real place where CO2 is returned is through respiration of surface aquatic organisms on the ocean-top?
Aldo Leopold is a name you may recall from our environmental history readings. He is often called the “father of wildlife management,” and you’ll encounter his work again later this year. He wrote a famous book called A Sand County Almanac and in it, this short story called “The Odyssey.” It is about “atom X” and its travels…wonder what element and biogeochemical cycle it represents?
“X had marked time in the limestone ledge since the Paleozoic seas covered the land.
Time, to an atom locked in a rock, does not pass. The break came when a bur-oak root nosed down a crack and began prying and sucking. In the flash of a century the rock decayed, and X was pulled out and up into the world of living things. He helped build a flower, which became an acorn, which fattened a deer, which fed an Indian, all in a single year. From his berth in the Indian’s bones, X joined again in chase and flight, feast and famine, hope and fear. He felt these things as changes in the little chemical pushes and pulls that tug timelessly at every atom.
When the Indian took his leave of the prairie, X moldered briefly underground, only to embark on a second trip through the bloodstream of the land. This time it was a rootlet of bluestem that sucked him up and lodged him in a leaf that rode the green billows of the prairie June, sharing the common task of hoarding sunlight. To this leaf also fell an uncommon task: flicking shadows across a plover’s eggs. The ecstatic plover, hovering overhead, poured praises on something perfect: perhaps the eggs, perhaps the shadows,or perhaps the haze of pink phlox that lay on the prairie.When the departing plovers set wing for the Argentine, all the bluestems waved farewell with tall new tassels. When the first geese came out of the north and all the bluestems glowed wine-red, a forehanded deer-mouse cut the leaf in which X lay, and buried it in an underground nest,as if to hide a bit of Indian summer from the thieving frosts. But a fox detained the mouse, molds and fungi took the nest apart, and X lay in the soil again, foot-loose and fancy-free. Next he entered a tuft of side-oats grama, a buffalo chip, and again the soil. Next a spiderwort, a rabbit, and an owl. Thence a tuft of sporobolus. All routines come to an end. This one ended with a prairie fire, which reduced the prairie plants to smoke, gas, and ashes. Phosphorus and potash atoms stayed in the ash, but the nitrogen atoms were gone with the wind. A spectator might at this point, have predicted an early end of the biotic drama, for with fires exhausting the nitrogen, the soil might well have lost its plants and blown away. But the prairie had two string to its bow. Fires thinned its grasses, but they thickened its stand of leguminous herbs: prairie clover, bush clover, wild bean, vetch, lead-plant, trefoil, and “Baptisia,” each carrying its own bacteria housed in nodules on its rootlets. Each nodule pumped nitrogen out of the air into the plant, and then ultimately into the soil. Thus the prairie savings bank took in more nitrogen from its legumes than it paid out to its fires. That the prairie is rich is know to the humblest deer-mouse; why the prairie is rich is a question seldom asked in all the still lapse of ages.
Between each of its excursions through the biota, X lay in the soil and was carried by the rains, inch by inch downhill. Living plants retarded the wash by impounding atoms; dead plants by locking them to their decayed tissues. Animals ate the plants and carried them briefly uphill or downhill, depending on whether they died or defecated higher or lower than they fed. No animal was aware that the altitude of his death was more important than his manner of dying. Thus a fox caught a gopher in a meadow, carrying X uphill to his bed on the brow of a ledge, where an eagle laid him low. The dying fox sensed the end of his chapter in foxdom, but not the new beginning in the odyssey of an atom.
An Indian eventually inherited the eagle’s plumes, and with them propitiated the Fates, whom he assumed had a special interest in Indians. It did not occur to him that they might be busy casting dice against gravity; that mice and men, soils and songs, might be merely ways to retard the march of atoms to the sea.
One year, while X lay in a cottonwood by the river, he was eaten by a beaver, an animal that always feeds higher than he dies. The beaver starved when his pond dried up during a bitter frost. X rode the carcass down the spring freshet, losing more altitude each hour than heretofore in a century. He ended up in the silt of a backwater bayou, where he fed a crayfish, a coon, and then an Indian, who laid him down to his last sleep in a mound on the river bank. One spring an oxbow caved the bank, and after one short week of freshet X lay again in his ancient prison, the sea.
An atom at large in the biota is too free to know freedom; an atom back in the sea has forgotten it. For every atom lost to the sea, the prairie pulls another out of the decaying rocks. The only certain truth is that its creatures must suck hard, live fast, and die often, lest its losses exceed its gains.”
So, can you produce a similar, creative short story about the carbon or nitrogen cycle?