Stories tagged Flow of Matter and Energy

May
30
2012

The issue:
About a month ago, a frack-sand mining operation near Grantsburg, WI, spilled some fine-grained sediment from a settling pond into a tributary of the St. Croix River. Local news media covered the story, and more details, for example, can be found in the Pioneer Press story by Dennis Lien.

So what’s the big deal?
Well, there are standards regarding water turbidity, which means that as a society we’ve decided that we don’t like cloudy water, at least in some settings and at some levels. For a naturally clear-water system like the St. Croix, increasing turbidity would alter the food chain at all levels. Algal primary producers rely on sunlight blocked by turbidity. Sight-based predation at the top of the food change would be altered. Benthic (bottom-dwelling) organisms that depend on coarse substrates could be smothered by siltation. Especially in the St. Croix, one of the last refugia for freshwater endangered mussel species, we must be on guard against too much fine sediment. And finally, where does the sediment end up? It’s filling up not only man-made reservoirs but also treasured natural lakes, iconically Lake St. Croix and Lake Pepin. These lakes are filling in with fine-grained sediment at about 3X and 10X their natural rates, respectively. (How do we know? See work done by the Museum’s St. Croix Watershed Research Station.)

Hey, it’s only a little bit...
Or was it? How much is a little? A little here, a little there, and a little more from over there -- it starts to add up. All water in a watershed runs downhill to the river, efficiently carrying both particles and dissolved materials. The river ultimately sees it all: all the disturbances, however seemingly minor, throughout the watershed. Rivers die a death of a thousand cuts. We have enough difficulty trying to control nonpoint sources of sediment and other pollutants. Stopping discharge of fine-grained materials from a mining operation is eminently fixable. It’s the right thing to do. Fortunately, all parties seem in agreement on this, including the mining company, which has repaired its leaky dike.

May
17
2012

Electricity from Viruses: Berkeley Lab scientists generate electricity using viruses.
Electricity from Viruses: Berkeley Lab scientists generate electricity using viruses.Courtesy Courtesy kso
Scientists from the Berkeley Lab have developed a way to generate electricity from viruses! Their method is based on the piezoelectric properties of the virus, M13 bacteriophage. Piezoelectricity is the charge that accumulates in certain solids when a mechanical stress is applied to them (squeezing, pressing, pushing, tapping, etc.) The scientists realized that the M13 virus would be a great candidate for their research because it replicates extremely rapidly (no supply problems here), it’s harmless to humans (always a good thing), and it assembles itself into well-organized films (think chopsticks in a box). It was these films that they layered and sandwiched between gold-plated electrodes to create their nearly paper-thin generator. When this postage stamp-sized generator was tapped, it created enough electricity to flash a “1” on a liquid crystal screen.

The potential here is that someday we could put these super-thin generators in any number of places, and harness electricity by doing normal, everyday tasks like walking or closing doors. I propose putting them in the shoes of marathon runners and then have cell phone charging stations along the route. Nothing is more maddening than waiting all day in the rain to get an action shot of your runner, only to find that your battery has since died by the time your slow-poke reaches the finish line. There’s always next year.

Dec
16
2011

Ten abandoned mining pits in Minnesota's Iron Range could have new life as pumped-storage hydroelectricity plants, according to a University of Minnesota,* Great River Energy, and Minnesota Power study.

[Hey, now: did you click on the hyperlink above? I don't put hyperlinks in posts for my own amusement, you know. They're for your viewing pleasure and learning enjoyment! Seriously though, click on them for great explanations, photos, diagrams, graphs, and more. You won't be disappointed.]

Match made in Minnesota: Wind and water "play nice" in pumped-storage hydroelectric technology.
Match made in Minnesota: Wind and water "play nice" in pumped-storage hydroelectric technology.Courtesy Steve Fareham

Pumped-storage hydroelectric technology sounds like something from a science fiction movie, but it's really just a neat combination of water and wind energy technology. What makes pumped-storage hydroelectric projects sexy is that they make it possible to store excess energy generated by wind turbines on windy days. This stored energy can then be used during the inevitable calm days -- addressing one of the biggest issues for today's wind energy industry!

How does it work?

It's basic physics, my friends: building potential energy and releasing kinetic energy. Specifically, excess energy generated by wind turbines "is used to pump water from a low-lying reservoir to a higher elevation pool" within the mine pit. This builds the potential energy of the water. Then, when that energy is demanded, "water from the upper pool is released generating hydroelectricity and refilling the lower pool." This releases kinetic energy, which can be turned into electricity.

How effective is it?

Researchers estimated that a pumped-storage hydroelectric facility built in Virginia, MN could output the same electricity as a "modest-sized" generator burning natural gas. However, at a cost of $120 million, the pumped-hydro facility would be more expensive than a comparable natural gas generator.

There are 40 U.S. locations currently employing pumped-storage hydroelectricity technology, but there are no definite plans for any such projects in Minnesota -- yet.

Read the Star Tribune's coverage of this story here.

*Including scientists from UMD's Natural Resources Research Institute, St. Anthony Falls Laboratory, and Humphrey School of Public Affairs; and funded largely by the Initiative for Renewable Energy and the Environment.

Sep
20
2011

There’s been some buzz about the relationship between clouds and climate recently, prompting Andrew Revkin of the New York Times’ Dot Earth blog to get his panties in a twist about the “…over-interpretation of a couple of [scientific] papers…”

What gives? I wanted to know too, so I’ve done a bit – ok, a lot – of research and this is what I can tell you: The heart of the discussion is not whether there is a cloud-climate connection (that’s clear), but rather over what that relationship behaves like. There are at least three possible theories, but before we get to those, let’s review some important background concepts.

Gimme the Basics First

Cloud Formation

First, scientists think of air as units of volume called air masses. Each air mass is identified by its temperature and moisture content. Clouds are basically wet air masses that form when rising air masses expand and cool, causing the moisture in the air to condense. You can see the process in action yourself just by exhaling outside on a cool morning. The Center for Multiscale Modeling of Atmospheric Processes has a webpage to answer your other questions about clouds.

Earth’s Energy Budget
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow).  Outgoing energy is radiated (red).  The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow). Outgoing energy is radiated (red). The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.Courtesy NASA

Energy from the Sun is essential for life on Earth. Let’s pretend the Earth has an “energy budget” where solar energy is like money, absorption is like a deposit, reflection is like a transfer, and radiation is like a withdrawal. It’s not a perfect analogy, but it’ll work for starters: Most of the incoming solar energy (money) is absorbed by (deposited into) the ocean and earth surface, but some is absorbed or reflected (transferred) by the atmosphere and clouds. Most of the outgoing energy is radiated (withdrawn) to space from the atmosphere and clouds. The figure to the right illustrates this process.

The Greenhouse Effect

Thanks to the greenhouse effect, our planet is warm enough to live on. The greenhouse effect occurs within the earth’s energy budget when some of the heat radiating (withdrawing… remember our budget analogy from above?) from the ocean and earth surface is reflected (transferred) back to Earth by greenhouse gases in the atmosphere. Greenhouse gases include carbon dioxide, methane, and water vapor. This National Geographic interactive website entertains the concept.

Climate Change

Climate change is occurring largely because humans are adding more greenhouse gases to the atmosphere. More greenhouse gases in the atmosphere means more heat reflected back to earth and warmer temperatures. Warmer temperatures might sound pretty good to your right now (especially if you live in Minnesota and could see your breath this morning as you walked to school or work), but it’s not. Why? Check out NASA’s really great website on the effects of climate change.

Alright, already. What’s the climate-cloud relationship?

From what I can tell, there are three possible theories about the climate-cloud relationship:

  • Clouds actively drive climate change. This is a linear process where clouds reflect too much heat back to Earth, which increases the average global temperature and causes climate change.
  • Clouds passively blunt climate change. This is a cyclical process where more climate change includes increasing average global temperature, which increases average global evaporation, which creates more clouds. More clouds absorb more heat, keeping the average global temperature from rising even faster and lessening climate change. This slows down (note: it does not stop) the rate of climate change.
  • Clouds passively amplify climate change. This is a cyclical process where more climate change includes increasing the average global temperature, which increases average global evaporation, which creates more clouds. More clouds reflect more heat back to Earth, which raises the average global temperatures and worsens climate change. This speeds up the rate of climate change.
  • So which is it? Probably NOT Theory #1. Maybe Theory #2… or maybe it’s Theory #3? Scientists aren’t quite sure yet, so neither am I, but the evidence is stacking against Theory #1 leaving two possible options. The next big question seems to be surrounding the size of the effects of Theory #2 and Theory #3.

    Using what you just read about cloud formation, the earth’s energy budget, greenhouse gases, and climate change (Woah. You just learned a lot!), what do you think? What’s the climate-cloud relationship?

    If you want, you can read more about what scientists are saying about the climate-cloud relationship here:

May
18
2011

R/V Hespérides, docked at Aloha Tower in Honolulu, Hawai`i
R/V Hespérides, docked at Aloha Tower in Honolulu, Hawai`iCourtesy C-MORE
How would you like to be aboard a ship, circumnavigating the globe, collecting samples from the world’s ocean?

That’s exactly what Spanish oceanographers are doing on their Malaspina Expedition aboard the Research Vessel, R/V Hespérides. Scientists and crew left southern Spain in December, reached New Zealand in mid-April, and recently arrived in Hawai`i. The expedition's primary goals are to:

  • build upon the historic 1789-1794 Malaspina expedition to promote interest in marine sciences among the Spanish public, particularly the nation’s youth
  • collect oceanographic and atmospheric data -- chemical, physical and biological – that will help evaluate the impact of global change
  • explore the variety of marine life, including microbes, especially those living in the deep sea
  • CTD: As this oceanographic instrument is lowered over the side of a ship, each gray Niskin “bottle” can be electronically triggered to collect a seawater sample from a different ocean depth.
    CTD: As this oceanographic instrument is lowered over the side of a ship, each gray Niskin “bottle” can be electronically triggered to collect a seawater sample from a different ocean depth.Courtesy C-MORE
    In connection with the latter two goals, the Malaspina scientists met with their colleagues at the Center for Microbial Oceanography: Research and Education (C-MORE). The two groups of scientists are working together. "We can exchange data on the local effects, what's happening around the Hawaiian Islands, and they can tell us what's happening in the middle of the Pacific," said Dr. Dave Karl, University of Hawai`i oceanography professor and Director of C-MORE.

    The Malaspina-C-MORE partnership is the kind of cooperation that can help solve environmental problems which stretch beyond an individual nation’s borders. The R/V Hespérides has now left Honolulu on its way to Panama and Colombia. From there, the scientists expect to complete their ocean sampling through the Atlantic Ocean and return to Spain by July. Buen viaje!

May
02
2011

the ocean's 5 major gyres
the ocean's 5 major gyresCourtesy NOAA
We often talk about the ocean ecosystem. And, indeed, there is really just one, world-wide ocean, since all oceans are connected. An Indian Ocean earthquake sends tsunami waves to distant coasts. Whitecaps look as white anywhere in the world. The ocean swirls in similar patterns.

However, oceanographers do find differences from place to place. For example, let’s take a closer look at the chemistry of two swirls, or gyres as they’re more properly called. Scientists have found a micro difference between the North Atlantic Gyre and the North Pacific Gyre. The Atlantic generally has really low levels of phosphorus, measurably lower than the North Pacific Gyre.

the element phosphorus among its neighbors in the Periodic Table of the Elements
the element phosphorus among its neighbors in the Periodic Table of the ElementsCourtesy modified from Wikipedia
Phosphorus is a very important element in living things. For example, it’s a necessary ingredient in ATP (adenosine tri-phosphate), the energy molecule used by all forms of life. Phosphorus is picked up from seawater by bacteria. All other marine life depends upon these bacteria, either directly or indirectly, for P. Therefore, if you’re bacteria living in the impoverished North Atlantic Gyre, you’d better be really good at getting phosphorus.

And they are!

Oceanographers at the Center for Microbial Oceanography: Research and Education (C-MORE) at the University of Hawai`i have made an important discovery. C-MORE scientists Sallie Chisholm, based at the Massachusetts Institute of Technology and her former graduate student Maureen Coleman, now a scientist at the California Institute of Technology, have been studying two species of oceanic bacteria. Prochlorococcus is an autotrophic bacterium that photosynthesizes its own food; Pelagibacter, is a heterotrophic bacterium that consumes food molecules made by others.

Pacific HOT and Atlantic BATS Stations: Microbial samples were collected at each location.
Pacific HOT and Atlantic BATS Stations: Microbial samples were collected at each location.Courtesy C-MORE
Drs. Chisholm and Coleman took samples of these two kinds of bacteria from both the Atlantic and Pacific Ocean. The Atlantic samples were collected by the Bermuda Atlantic Time-Series (BATS) program. The Pacific samples were collected in the North Pacific Gyre (about 90 miles north of Honolulu) by the Hawai`i Ocean Time-Series (HOT) program. The scientists discovered surprising differences in the genetic code of the bacteria between the two locations:

  • First of all, the Atlantic populations of both bacterial species have more phosphorus-related genes compared to their Pacific cousins. (Picture Atlantic microbes in Superman outfits with a big "P" on their chests!)
  • Secondly, in the Atlantic, Prochlorococcus has different kinds of P-related genes compared to Pelagibacter. Perhaps this means the two microbial species have evolved over time to use different phosphorus sources, to avoid competing with one another for this limited resource.

Drs. Chisholm and Coleman have discovered important micro differences between bacteria of the same species in two oceanic gyres. Now we can better understand how these microbes are working to recycle an important nutrient beneath the whitecaps.

Reference: October 11, 2010 issue of the Proceedings of the National Academy of Sciences

Apr
12
2011

A map of radiation-contaminated areas around Fukushima: Radiation from the accident has spread dozens of miles, but most of the area (the blue) is still showing very low levels ("low, but not insignificant," according to the National Nuclear Safety Administration.)
A map of radiation-contaminated areas around Fukushima: Radiation from the accident has spread dozens of miles, but most of the area (the blue) is still showing very low levels ("low, but not insignificant," according to the National Nuclear Safety Administration.)Courtesy NNSA
The tsunami- and earthquake-caused disaster at Japan’s Fukushima nuclear power plant has been upgraded to a 7, a “major accident.” 7 is the highest (worst) rating on the International Nuclear Events Scale, and Fukushima and Chernobyl are the only two events to have received the rating. As Liza pointed out, it should be said that Fukushima has so far only released about a tenth of the radiation released from the Chernobyl disaster.

While there were explosions in the reactor housing at Fukushima in the days after the earthquake, none of them were on the scale of Chernobyl, where the reactor itself exploded, and where graphite fires continued to burn for days, spreading huge quantities of radioactive materials long distances. At Fukushima, the vessels containing the reactors are largely intact, and the plant is not producing tons of radioactive smoke.

Still, where authorities seemed to have been giving overly optimistic assessments of the situation before, now it looks like they’re doing a better job of acknowledging potential worst-case scenarios—since the plant is still releasing radioactive materials, plant operators say that it could eventually equal Chernobyl in terms of radioactive output.

The situation was upgraded to a seven after officials extended the evacuation area around the plant from a twelve-mile radius to a region that includes five towns, home to tens of thousands of people. The affected region isn’t a perfect bull’s-eye, like you might see on some maps—the radiation is spreading unevenly due to wind and the shape of the land, meaning some areas will be less affected, while others are receiving a greater dose of radiation. The map posted above shows the contamination as of April 3—radiation has spread dozens of miles, but most of it (in the blue) is still at very low levels. The units are for radiation absorbed in an hour. As a reference point for those numbers, the Nuclear Regulatory Commission estimates that the average American absorbs about 620 mRem a year, which equals about 0.071 mRem/hr.

Authorities are saying that it will take months to totally get the reactors under control, and years to clean up the plant and surrounding area. No one has died from acute radiation exposure (although several workers have been hospitalized), but it could be months or years before the impact on those exposed reveals itself.

Apr
11
2011

Take a break and listen to the sounds around you. What do you notice? Is there anything surprising that you've been tuning out? How do the sounds change over time, and do they improve or degrade your well-being?
Do you hear what I hear?: Way up in the floor, Omnitheater...
Do you hear what I hear?: Way up in the floor, Omnitheater...Courtesy David Benbennick

It's easy to think of sound as a side-effect of important behaviors like communication, transportation, building stuff, etc. But could sound be important all on its own, worthy of our attention? We all live within environments of sound, and so do animals. In fact, there's a emerging field called soundscape ecology, which aims to study sound and its relationship with ecosystem health.

Traditionally, studies focus on the sound of one animal to understand its communication. For example, one scientist recently decoded prairie dog-ese.

But soundscape ecologists don't look at individual animal sounds so much as the bigger picture--they want to know which animals are loud or quiet, which ones have higher or lower pitches, which animals follow the sounds of other animals, and then they try to put it all together to understand the soundscape as a system that shows how animals interact with each other through sound. They also want to understand how human sounds impact these soundscapes.

Researchers compared bird life around noisy equipment that compresses natural gas with similar — but quiet — habitat. In Alberta, they found that birds had fewer offspring at the noisy sites. Similar results came from the Southwestern U.S.

Eee: my bat-dar doesn't work in loud environments!
Eee: my bat-dar doesn't work in loud environments!Courtesy Stahlkocher

Species that use echolocation, such as bats and (potentially extinct) Yangtze river dolphins, have trouble locating prey and moving safely through their habitat when unexpected sounds disrupt their echos.
Tamarin: My cage is alive with the sound of muuuusic!
Tamarin: My cage is alive with the sound of muuuusic!Courtesy Helenabella

Musician David Teie has even shown that he can create music that impacts the moods of tamarins.

And then there are the impacts of human sound on humans. Garret Keizer writes in his book, The Unwanted Sound of Everything We Want, that he "chose to write a book about noise because it is so easily dismissed as a small issue. And because in that dismissal I believe we can find a key for understanding many of the big issues."

I'm loud: how often do you see me flying low over nice neighborhoods?
I'm loud: how often do you see me flying low over nice neighborhoods?Courtesy John Pozniak
Keizer distinguishes between sound and noise, which is unwanted sound. He discusses how soundscapes are divided up according to wealth and sociopolitical power--that there are people who make noise and people who listen. Airports or loud factories might be built near less affluent neighborhoods, for example. Keizer asks us to recognize that the sounds we make can have impacts beyond us:

A person who says “My noise is my right” basically means “Your ear is my hole.”

So sound can be an indicator of larger social issues or ecological disruptions. As you read this, do you notice anything about the sounds around you that make you think of a bigger issue or problem?

Mar
29
2011

By the way, when you read about the gigatons of carbon emissions that human activities emit each year, it's helpful to have some perspective:

Let's talk gigatons--one billion tons. Every year, human activity emits about 35 gigatons of [carbon dioxide] (the most important greenhouse gas). Of that, 85% comes from fossil fuel burning. To a lot of people, that doesn't mean much -- who goes to the store and buys a gigaton of carrots? For a sense of perspective, a gigaton is about twice the mass of all people on earth, so 35 gigatons is about 70 times the weight of humanity. Every year, humans put that in the atmosphere, and 85% of that is power. Large actions, across whole nations and whole economies, are required to move the needle.

By comparison, our atmosphere is small--99.99997% of our its mass sits below the Karman line, which is often used to define the border between Earth’s atmosphere and outer space. At 62 miles above Earth's surface, it’s about as high as the distance between St. Paul, MN, and Menomonie, WI.

The oceans also absorb some of that carbon dioxide, but not without consequence.

Of course, the great part about being responsible is having capability--if our inventions bring about such transformations in the air and oceans, then couldn't we be inventive enough to reduce their negative impacts?

Mar
17
2011

Aren’t budgets all about money? Don’t they track how many $$$ come in and how many $$$ go out?

That’s right; so what’s a carbon budget? A carbon budget tracks how much carbon, C, goes in and out of a natural area.

Right now, we’re worried about too much C going into our planet’s atmosphere. This excess C is causing global warming, sea level rise, ocean acidification and other environmental problems. These are BIG problems! We can begin to fix these problems if we do a carbon budget and really know how much carbon is where.

Carbon Budget Study Area: How much carbon is in the shallow, coastal seawater?
Carbon Budget Study Area: How much carbon is in the shallow, coastal seawater?Courtesy Sergio Signorini, North American Carbon Program
Along with others, scientists at the Center for Microbial Oceanography: Research & Education (C-MORE), based at the University of Hawai`i, have begun to track C in the ocean off the eastern United States. The study area includes a LOT of water! -- all the seawater from high tide out to 500 meters deep, shown by the black line in the map, in the Gulf of Maine (GoM), the Mid-Atlantic Bight (MAB), and the South Atlantic Bight (SAB.)

Imagine your money budget. Let’s say we track your $$$ in and out of 4 categories. Money comes into your pocket from 2 categories, mowing the neighbor’s lawn and babysitting. Money goes out when you pay for movies and snacks.

In the same way, scientists want to track C as it moves between the coastal water “pocket” and 4 nearby areas: the coastal land, the atmosphere above, seafloor below, and the deeper ocean offshore. Where is C leaving the coastal water? Where is it entering?

But wait! Coastal zones are only small slivers of water, compared to the open ocean around the world. Why bother to track carbon in coastal waters?

Ah ha! Coastal waters are very important in C budgeting. Notice the red color in the map above. Red means there's a lot of chlorophyll. Chlorophyll is the green pigment important in photosynthesis, the process that plants use to take in C and fix it as sugar. The red in the map shows that coastal waters are richer in carbon than the open ocean.

Understanding the C budget of coastal waters is one small but important step in solving global warming and other environmental problems.

Reference: Ocean Carbon & Biogeochemistry Winter 2010 OCB Newsletter; Vol. 3, No. 1.