When people think of life in the seas, it is often the majestic that comes to mind, such aswhales, sharks, rays and coral reefs, or our own sustenance in the form of the fish that feed billions of us around the world.  Rarely do we think of plankton, the tiny organisms found across the world’s oceans. Plankton are comprised of two general types: phytoplankton, which are microscopic plant-like cells, and zooplankton, the tiny animals that graze the phytoplankton (there are, however, some plankton that can reach nearly 2 m wide and weigh more than 200 kg, such as the Nemopilema nomurai, or the Nomura jellyfish)  Despite their size, these small life forms are enormously important for the planet in several ways.  First, they are the foundation of the marine food web as they provide 50% of the oxygen we breathe. Additionally, they play an integral role in the global carbon cycle, which you can learn more about through GLOBE’s global carbon cycle activities.

The word plankton is derived from the Greek word “planktos”, which means drifter, since plankton drift at the whim of the ocean’s currents.  While they have almost limitless distribution across the world’s oceans, their vertical extent is limited to the sunlit layer of the water, known as the photic zone. Here they use sunlight to photosynthesize, converting carbon dioxide (CO2) into organic compounds and producing half the oxygen we breathe. With this action, plankton are as important as the trees and plants in making our planet habitable.

Schematic showing the photic zone. Image from Pearson Education.

In addition, by converting CO2 into organic compounds, plankton play both short term (centuries) and long term (geological time frames) roles in the global carbon cycle. When they die and sink to the ocean floor, they may be part of a long term sequestering of carbon as part of the ocean floor or become part of a carbon pump cycle that moves carbon throughout the oceans and helps manage atmospheric CO2.  The oceans take in CO2 at greater levels in colder waters near the poles. Because that cold water is also denser, it sinks and transfers the carbon to the deep ocean where it can circulate. Eventually, this carbon-rich deep water returns to the surface at upwelling regions where plankton consume it as part of their biological processes and then return it back to the depths in death.

While there is still much to be learned about plankton, scientists are finding evidence that these organisms are under significant threat.  Two changes are of particular concern: rising ocean temperatures and changing pH. Since plankton live at the ocean’s surface, they are particularly susceptible to temperature changes in the water and scientists have begun recording alterations in the distribution, abundance, and seasonality of plankton in both the Atlantic and Pacific Oceans. In addition, increasing atmospheric concentrations of CO2 are affecting the ocean’s pH. As carbon dioxide (CO2) enters the sea surface, it dissolves in the water (H20) and forms a weak acid called carbonic acid. As atmospheric CO2 increases, more enters the sea and scientists are documenting increasing acidity in ocean water. Many zooplankton rely on calcium carbonates in the water to help build their structures and these minerals are less available in more acidic conditions.

A closeup view of plankton. Photo courtesy of Janis Steele

These changes occurring in the oceans will have profound consequences for the ecology of the whole planet.  Here aboard Llyr, we are participating in a citizen science campaign to monitor plankton.  We are using two simple tools to do these studies: a Secchi disk and a plankton net.

The Secchi disk is one of the earliest and simplest devices to study plankton in their environment. Because phytoplankton affect the turbidity, or clarity, of the water, an easy visual experiment can tell us a great deal. Invented in 1865 by Pietro Angelo Secchi, the latest version we’re using aboard Llyr is a weighted, white plastic disk attached to a length of rope marked in 50 cm intervals.  We lower the disk into the water and the depth at which is disappears is called the Secchi depth.  Not only are we recording the turbidity but also the depth to which phytoplankton can grow in the water column. Our data from these experiments in submitted to Plymouth Institute in England, where Dr. Richard Kirby has initiated a campaign to enlist seafarers in monitoring plankton around the world (See Ocean Drifters; A Secret World Beneath the Waves, R. Kirby, Firefly Books 2011).

Holding a secchi disk. Photo courtesy of Janis Steele

The second device we are using to study plankton is a plankton net. Charles Darwin used a plankton net during his famous voyage aboard the Beagle.   Our 200 micron net is sized for the collection of larger zooplankton. As we tow the net behind Llyr, zooplankton are strained from the water and washed in to the collector at the bottom of the net. We are then able to observe and photograph these creatures using Llyr’s microscope.  There are two types of zooplankton: the holozooplankton that spend their whole life cycle as plankton, and the merozooplankton, those creatures that spend just a part of their life cycle as plankton in larval stages, maturing to creatures that live on the sea bed, such as urchins, crabs, worms and mollusks.

A plankton net. Photo courtesy of Janis Steele.

Examining creatures collected from the net. Photo courtesy of Janis Steele.

Today, new and more sophisticated technologies are available to study plankton. It is even possible to observe them from space due to the fact that phytoplankton have photosynthetic and other pigments which color the water when they bloom!  Despite the importance of plankton and even though they live on the surface of the sea, there is still much more to learn about plankton, these tiny organisms that make life on Earth possible.

Suggested activity: While these studies are in the ocean, plankton are found in freshwater too.  In conjunction with GLOBE hydrology protocols, you can collect water samples to look under a microscope at the types and numbers of plankton. By continuing this experiment over many years, you can begin to learn of the relationship that Steele and McCutchen describe here.  If you’ve already examined plankton, we’d love to hear about it!  Leave a comment here or on our Facebook page, or send us an email to science@globe.gov.

The Great Lakes are separated from the Mississippi River by six miles!  The Mississippi River (also known as the Great River) collects water from 31 states and 2 provinces on its 2350 mile course from Lake Itasca to the Gulf of Mexico. It was the inspiration for numerous explorations; famous explorers like LaSalle, DeSoto, Joliet, Radisson, Hennepin, Marquette, Nicollet, Zebulon Pike, and Schoolcraft labored to discover new lands in an undiscovered world.  Their expeditions took them throughout the Mississippi River Basin; the river reaching its source at a village along the banks of Lake Itasca.

A map of the location of Lake Itasca and the Mississippi River, as well as its watershed. From The University of Minnesota.

The Mississippi River is 3782 km (2350 miles) long and averages 1.6 km (1 mile) wide, making a surface area of 6086.5 square kilometers (2,350 square miles) while Lake Superior has a 2494.5 kilometer (1550 mile) shoreline and 82,102.6 square kilometers (31,700 square miles) of surface area.  Lake Superior’s shore is divided between three states and one Canadian Province while the Mississippi River has 10 states that share its shore.  But more impressive than the surface area of the two water bodies is comparing the two watersheds.  A watershed, also known as a catchment basin, is a large area where rain, rivers and other flowing water bodies, and runoff flow towards a single body of water (for example, an ocean).    For Lake Superior the watershed is only 127,686 square kilometers (49,300 square miles) – making an 82:128 ratio of water to watershed; a ratio of approximately 1.5 to 1.  The Mississippi River drains 3,108,000 square kilometers (1,200,000 square miles) – a ratio of 6.1:3,108 or 510 to 1.  The Mississippi River watershed includes 31 states and 2 Canadian Provinces.

Lake Itasca is the agreed upon source (some wanted to consider Elk Lake and its little outflow to Itasca to be the source, and others said Nicollet Lake and its small boggy stream is the real headwaters) due to the ruling of the Minnesota government.  It is an inspiring place with forests of large, old red and white pines and a picturesque beginning to the river that reflects our human influence – originally the river just ran out of the boggy landscape at the north end of the lake, but rocks were put in place and a channel designated to become the official start.  Millions have walked these rocks thinking that it is a natural spot and loving the idea of stepping in the water as it leaves for its rendezvous with the Gulf of Mexico.

A look at Lake Itasca. From gallivance.net

With this geographic landscape in mind we began to think of Minnesota as a distributary – a place which outsources its water to the Great Lakes and the Gulf, and in fact to Hudson Bay and the Arctic through the northern flow of the Red River on the Minnesota and North Dakota border.  We receive it in pure form and then it begins to move on, but what happens as it moves is the problem.  Lake Superior has its long axis on an East/West bearing so the people who share the waters also experience similar climate.

Unfortunately, rivers have been thought of as places to get rid of waste – all kinds of waste – because the water naturally takes the materials downstream.   Those who live upstream are more ignorant to the issue, but more people live downstream and have only a limited amount of resource to use as pesticides, herbicides, fertilizers, lawn and road runoff, petroleum products, invasive species, and concrete structures are added to its natural channel.  Living downstream is dangerous and the impact of thoughtless use of water is something we have to come to terms with.  The Mississippi flows from North to South and therefore crosses many biomes and climate lines and these in turn affect the cultures that share the river.  Another big difference is the fact that people do not all share the same waters.  Each new tributary stream adds to the river and that water moves downstream making each mile of the river different than what is upstream.

On our hike around Lake Superior we shared the message that there are two things that are most essential to life – clean air and clean water – and there is no room for compromise.  Both must be treated as the precious commodities they truly are.

So from Full Circle to Full Length, we decided to carry our message and hope to create a positive forum for people to think about their legacy, to care about future generations and to leave the two most precious commodities in the healthy state required for life.Through subsequent blogs, we will post the anthropological observations from our scouting trip, as well as  biology, engineering, hydrology, and phenology connections.

Suggested activity: Do you live along the Mississippi River or one of its tributaries?  You can use GLOBE hydrology protocols and collaborate with a school either down or upstream to compare the differences in your measurements.  You can find schools along the Mississippi and/or its tributaries on the GLOBE website.  Also explore the Watershed Dynamics ESSP as well as the “Model a Catchment Basin” learning activity to understand more about rivers and their watershed.   

Also, be sure to remember that World Water Day is March 22.  Let us know of your plans to celebrate this important day by sharing in a comment or on our Facebook page.

In May, we took a look at Qatar and Saudi Arabia, also part of the GLOBE Near East North Africa region, who are facing similar concerns, with water scarcity being the major worry. Vegetation in the region has adapted to the dry climate; however, as the climate continues to change, agricultural success is expected to fluctuate more wildly.  While this is also a concern in Oman, water scarcity is tied to soil salinity – a problem the country is facing more frequently.

Salinity is the amount of saltiness or dissolved salt content (sodium chloride, magnesium and calcium sulfates, and bicarbonates) in a body of water or in soil.  As the amount of rainfall decreases while temperatures increase, more salt is able to accumulate in the soil due to increased evaporation rates.  Since 1990, the balance between use of lower salinity water, a.k.a. freshwater, and the annual freshwater recharge has been disturbed so much that crops have been yielding less and fields are abandoned.

Why do crops yields suffer from higher salinity?  Higher soil salinity results in plants not being able to draw as much water from the soil.  And in locations such as Oman that require irrigation, more salt is added to the soil than is removed.  Additionally, Oman’s coastal locations are favorable for sea salt spray to accumulate in the soil.  It is possible to use two GLOBE investigations, soils and hydrology, to monitor soil and water properties to determine the current salinity and any rate of change.  Sultan Qaboos University has been looking into ways to mitigate soil and water salination, especially since the country has been facing water shortages.

The Batinah region of Oman, an area greatly affected by high soil salinity, photo from tourismoman.com.au

Hope isn’t completely lost, as there are means to correct salt-affected soils.  This includes improving drainage or reducing evaporation by using mulches.  With these mitigation efforts, it is anticipated that soil salinity can drop and crops can flourish again.

Are you a GLOBE school using hydrology and/or soil protocols to look at salinity?  Have you noticed any changes in your data?  We’d love to hear from you!  Leave us a comment or send us an email at science@globe.gov.

-Jessica Mackaro

The Mississippi River in New Orleans (photo courtesy of Dr. Donna Charlevoix)

The Mississippi River is the lifeblood of New Orleans and has so impacted the city that the city was actually developed around it. The first buildings were constructed around the river edge, which has the highest ground, and now gives the city a crescent shape if you were looking down on it from above.  This is why the city is sometimes referred to as the Crescent City.

An aerial photo of New Orleans, image from smithsonian.org, photographer Tyrone Turner

The Mississippi River is the largest river in North America and travels over 4000 km from Minnesota south to Louisiana where it drains into the Gulf of Mexico. This river, like all rivers, is living and the health of the river can be measured in several ways. This is similar to how you can use GLOBE protocols to measure environmental phenomena in different ways, depending on what information you want to discover.

Here in New Orleans we see the river every day as we walk to the scientific conference. The very presence of being in New Orleans triggers reminder of Hurricane Katrina in 2005, which was the worst hurricane experienced by the city and the costliest and deadliest hurricane to impact the United States. You may be surprised to learn that the impacts of hurricanes and the health of the river are closely related.

All along the Mississippi River, the land is very fertile and there is abundant agriculture. The natural flooding of the river on to the flood plain over hundreds of years has deposited nutrients and minerals into the soil resulting in soil that is very fertile. However, the agriculture is impacting the river because runoff from these agricultural areas contains excess amounts of nitrogen and phosphorus – they are changing the chemical makeup of the river. As the water flows downstream and into the Gulf of Mexico, the pollutants accumulate at the mouth of the river and have created a “dead zone” just off the Delta, which adversely impacts aquatic life. An aquatic dead zone is an area with very low oxygen content; we say that it is hypoxic. The Gulf of Mexico is not the only dead zone. This image produced by NASA shows dead zones in several locations around the world with large concentrations along the eastern seaboard of the United States and a second area in northern Europe.

Do you live near one of these dead zones? If you are near an aquatic dead zone or live near any body of water, use the GLOBE hydrology protocols to investigate the quality of the water. Either add a comment or send us an email to let us know what you find!

-JSM

The map below shows the location of the San Francisco Bay, marked by the bubble with an A, from Google. In 1972, the Clean Water Act was passed, working to improve the quality of water bodies within the United States by regulating the pollutants that were dumped into the ocean.  The quality of the water in the Bay began diminishing in the early 1900’s.  During World War II, the San Francisco Bay became a large war time port and ship building center.   By the time of the 1950’s and 1960’s, the Bay was so polluted that it literally smelled like raw sewage.

So when and why exactly did the porpoises leave the Bay?   The answer isn’t exactly clear.  From bone records found in the Bay, porpoises have made this location a home for hundreds of years.  As late as the 1930’s, there were reports of porpoise sightings.  But in the last 70-80 years, these reports were fewer and far between. Approximately three years ago, the first porpoises were spotted returning to the Bay.  Since then, Jonathan Stern,  a whale researcher from San Francisco State University who was featured in the QUEST article, and other researchers have been looking to find the answers to why they left in the first place, and what has caused them to return after so many years.   According to Stern, even though the Clean Water Act was passed in 1972, it takes awhile for the food supply to return, and even longer for predators of that food to return.

Harbor porpoises as seen from the Golden Gate Bridge. (Photo: William Keener/Golden Gate Cetacean Research). From the QUEST Science blog

While it isn’t easy to collect data from such a large body of water, the same types of phenomena can be observed in local streams and rivers that many GLOBE schools are visiting to record data.  The Hydrology Chapter of the GLOBE Teacher’s Guide has quite a few protocols that students could use to examine the quality of the streams and its effect on life.

For instance, a change in water pH, which can be collected through the pH protocol, can affect the types of macroinvertibrates found in the water body.  This in turn has an effect on the food chain – whether that be through an increase or decrease in food supply.  This would be an interesting research study to do over the course of many years - following local legislation and news articles on water quality, monitoring the water as a GLOBE school, and seeing if there are any changes found.

To read more information about the return of the San Francisco Bay harbor porpoises, head on over to the QUEST science blog.  If you’re a GLOBE school and are participating in any of the hydrology protocols, we’d love to hear from you and your findings!  Leave a comment here or email us at science(at)globe.gov!

-jm

So what exactly is the process that causes the glowing waves?

Algae!  This particular type of algae, Lingulodinium polyedrum, began blooming in late August.  During the day, the waters off the coast of California turn a brownish-red color, according to The University of California – San Diego scientists.  Take a look at what this microorganism looks like under a microscope:

Image from The Smithsonian

But while the ocean during the day looks quite murky, the ocean at night is a much more exciting experience.  Each microorganism will give off a flash of blue light when moved around.  So while one of these organisms is difficult to see in such a large body of water, imagine uncountable numbers being moved all at once!  For more information on the chemistry behind bio-luminescence, take a look at The University of California – Santa Barbara’s website dedicated to this phenomena.

Typically algae blooms are not welcome in bodies of water. Harmful algal blooms can cause significant problems for humans and sea life.  This specific type of algae produces mild toxins that can harm sea life, while only causing minor sinus and ear infections in humans who swim in algae infested waters.

While the most favorable conditions for algae blooms aren’t readily understood, many scientists believe the right combination of available nutrients, nutrient ratio, and water temperature are the main causes.  So a GLOBE school that is near the ocean may be able to use hydrology protocols, such as water temperature, to monitor water temperatures and note the relationship between temperature and algae growth.

If you live in Southern California, and you are able to head to the beaches, you’re in for a site!  If you live in another part of the world, here’s a video from Man’s Best Media showing the electrifying effect of this algae.

Red tides don’t only occur on the Pacific Coast of the United States.  They can occur off the coast of Australia, The United Kingdom, and Chile.  For example, in 2010, more toxic algae bloomed in the Baltic Sea off the coast of Sweden.  Here’s an image of this bloom, taken by the European Space Agency’s Envisat satellite on July 11^th, from the BBC.

-jm

Figure 1. Rain gauge used for observations in my backyard. Normally, there is a funnel and small tube inside, but it doesn’t fit very well, so we pour the rain into the small tube after each rain event. This gauge is similar to those used by the U.S. National Weather Service. This gauge is about 25 cm in diameter.

Figure 2. Plastic raingauge matching GLOBE specs. This gauge is about 12 cm in diameter. Note the tall tree in the background.

Neither gauge is in an ideal location. In both cases, there are nearby trees (Fig. 2, map) which might impact the measuring of the rain. This is a problem a lot of schools have: there is just no ideal place to put a rain gauge. We were particularly worried about the plastic gauge, which was closer to trees than the metal gauge.

Why do we have two gauges? The metal gauge was hard to use: its funnel didn’t fit easily into the gauge, so we had to pour the rain from the large gauge into the small tube after every rainfall event. We got the plastic gauge to replace the metal one. We put the gauge on the fence because it was well-secured. But the first six months we used the new gauge, the rainfall seemed too low compared to totals in other parts of Boulder. So, I put the metal gauge back outside and started comparing rainfall data.

Figure 3. Map of our backyard. Left to right (west to east), the yard is about 22 meters across. The brown rectangular shape is our house; the circles represent trees and bushes. The numbers denote the height of the trees and bushes. The 10-m tree is an evergreen; the remaining trees and bushes are deciduous. The southeast corner of the house is about 3 m high.

How did the gauges compare?

Starting this summer, I started taking data from both gauges. Unfortunately, it didn’t rain much. And sometimes, we were away from home: so this is not a complete record. But I don’t need a complete record to compare the rain gauges.

Table: Rain measurements from the two rain gauges

The results (in the table, also plotted in Figure 4) look pretty good. With the exception of the one “wild” point on 6 October 2008, the measurements are close to one another. We think that the plastic gauge was filled when the garden or lawn next door was watered. This would not be surprising: we have found rain in the plastic gauge when there was no rain at all.

I learned after writing this blog that Nolan Doeskin of CoCoRaHS (www.cocorahs.org) has compared these two types of gauges for 12 years, finding that the plastic gauge measures slightly more rain (1 cm out of 38 cm per year, or about 2.6%).

Figure 4. Comparison of rainfall from the two rain gauges in our back yard. Points fall on the diagonal line for perfect agreement.

I learned two things from this exercise.

First, I probably should have used the two gauges before I stopped using the metal one. That way, my rainfall record wouldn’t be interrupted if the new gauge was totally wrong. (I was worried that the trees were keeping some rain from falling into the gauge. This would have led to the plastic gauge having less rainfall than the metal gauge. And, since the blockage by the trees would depend on wind direction and time of year, I wouldn’t have been able to simply add a correction to the readings.) Fortunately, the new and old gauges agreed.

In the same way, if you want to replace an old thermometer with a new one, it’s good to take measurements with both for awhile, preferably in the same shelter. Suppose the new thermometer gives higher temperatures than the old one. If you want to know the temperature trend, you can correct the temperatures for one of the two so that the readings are consistent.

The second thing I learned is that it is o.k. to reject data if there is a good reason (such as people watering their lawns). It’s also important to note things going wrong – like my spilling a little bit of water on 15 August. If you keep track of things going slightly wrong (or neighbors watering the lawn), you can often figure out why numbers don’t fit the pattern.

I will continue to compare records for awhile, to see whether the readings are close to one another on windy days. If they continue to be similar, I will be able to try a method to keep birds away from the rain gauge that was developed by a GLOBE teacher – Sister Shirley Boucher in Alabama. Keep posted!

The GLOBE Inquiry Model is a simple way to describe how scientists investigate questions. It’s easier to deal with the inquiry process in the classroom if the steps are described. In reality, the way scientists “do” inquiry is much messier, and different scientists have different ways of doing their research. But, in the end, they have to do all the same things that will be described here. Often, scientists return to each step a number of times while they are learning about the question they are investigating. This was illustrated a little bit in the puddle blog.

To summarize, here are the steps

1. Observe natural phenomenon
2. Explore, extend, and refine observations
3. Develop investigation plan
4. Conduct investigation
5. Analyze data
6. Summarize findings and conclusions
7. Share findings and conclusions
8. Identify new research questions

This is but one summary. There are many other ways of summarizing the inquiry process. For example, “Form a hypothesis” is often a listed step (in fact, is an option under “Explore, extend, and refine observations.”) Also, “Conduct Investigation” includes making observations, but they are now more systematic.

Note that not all scientific investigations start with a hypothesis. In some investigations, a question is narrowed down until an answer seems possible given the time and resources available for the investigation. For example, it is quite legitimate to ask “Has snowfall decreased in my hometown in the last 50 years?” Sometimes scientists start investigations with a question and develop a hypothesis in the course of the study. Other times, scientists alter their hypotheses as they discover new things.

Okay, let’s get started.

1. Observe the natural phenomenon
The way I work is that I look for surprises – something I can’t easily explain. Maybe if I don’t understand it, other people don’t either.
In this case, I saw a puddle that remained large (and possibly even grew) even though it had not rained or snowed for several days. Also, the puddle remained liquid, which seemed surprising given subfreezing temperatures for several days. This didn’t make sense to me. So I started to watch the puddle.

2. Explore, extend, and refine questions
In February, I walked to the puddle several times in a few days, to see what was happening to it. The fact that it was still there intrigued me. Also, I discovered a line of fire hydrants on the same side of the road as the puddle, which meant that there was an underwater pipe. (Was the pipe broken?) Finally, I noticed salt crystals on the road one morning; with newly fallen snow melting around the salt crystals. (Could the salt be keeping the water from freezing?)

3. Develop investigation plan
Given the observations I had made – no rain, possible broken underground pipe, very cold weather, I had two hypotheses regarding the origin of the puddle, namely:

1. The puddle was the result of a break in the pipe connecting the fire hydrants.
2. The puddle was fed by water running downhill beneath the surface (it was frozen at the surface).

I also had two hypotheses why the puddle was liquid.

1. The puddle was supplied by underground water that was warm enough to be liquid
2. The puddle didn’t freeze because of the salt on the road.

To see whether a leaky pipe caused the puddle:

1. In February, I decided to interview people who knew about the road.
2. In March, I decided to check to see if the puddle was there after several warm and dry days. If there was a leaky pipe, I would have expected to see a puddle.

To see whether the puddle came from water below the frozen ground:

1. In February, I decided to look for data showing it was possible for the soil (and water) below the surface to be warmer than freezing during short (week-long) periods with air below freezing. (It would have been ideal to take measurements near the puddle, but I did not have the proper equipment).
2. In February, I also decided it was important to check to see whether there was water on the surface, even thought it was quite cold.
3. In March, I decided to check to find how underground water could flow onto the street.

Notice that this was not all done at once. I went back and refined my investigation plan, when I found out I had the opportunity to check further.

4. Conduct Investigation

To investigate whether the puddle was supplied by underground water:

1. I continued to observe the puddle to see whether it was changing in size (February).
2. I obtained wintertime data from Smileyberg, Kansas, and Bondville, Illinois, to see how soil temperature behaved during ~week-long periods when temperatures were much colder than normal (and also below freezing). I plotted the air temperature and soil temperature during the cold periods, to confirm that the soil temperature could be above freezing (February).
3. I looked for openings in the street and curb for underground water to flow through to supply the puddle.

To investigate the broken-pipe hypothesis:

1. I asked my nephew about whether the pipe could be broken. He thought it unlikely because the pipes were very new.
2. I checked the puddle location a month later, when warm weather dried the ground. There was no puddle, which made me think that the pipe was probably o.k.
3. Also, I knew from my family and the appearance of the ground that the pipe had not been repaired.

To investigate the salt hypothesis:

1. I looked for evidence of salt on the road (salt crystals, melting around the crystals, and white stain on the road where salty water had dried up).
2. I interviewed a colleague who had been involved in studying arctic ice.

5. Analysis of the data

1. I compared the puddle sizes (from memory and photographs).
2. I plotted the air temperature and soil temperature at several levels to confirm that the soil could remain above freezing even when the air got quite cold.
3. I compiled evidence of salt (the crystals, the stain the road where the puddle had been, Even the slushy appearance of the water was associated with it being cold and salty).
4. I compiled evidence that the pipes were not leaking (the pipes were new, the contractor had a good reputation, there was no puddle after a dry spell, and it was obvious no one had repaired the pipe between my visits to the site).

6 and 7. Summarizing findings and conclusion and sharing findings

By doing my blog, I was working on this part even before I had finished the investigation. Were I to write this as a report, I would summarize the hypothesis, methods, and results as if they were done in an orderly manner. The timing of a result – be it before or after I was working on hypotheses, doesn’t really matter in the final report.

Were I not doing a blog, I would have recorded similar information in my laboratory notebook, so that I could be reminded of the details when I wrote the final report. (Here is a sample final report.)

8. Identify new research questions

It is rare that someone finishes up a research project without thinking of more questions. I was thinking of them the entire time. I was so excited about the possibility of underground water causing a liquid puddle when the air temperature was well below freezing, I didn’t think of the effects of salt. That is, until the next day when I saw the snow melting around the salt crystals. Now, I’m wondering if the cars disturbing the puddle kept it from freezing as well. And tomorrow I might think of other ideas.

It is not easy to decide when to finish a study. If you are a student, you have a due date that forces you to stop. If you are scientist, and are being paid to finish a project by a deadline, you also have to stop – at least until you can find someone to pay you to answer your next question.

In fact, scientists I know usually find that their investigations often lead to more questions than answers.

In the same way, thinking about the evidence kept giving me new ideas for what to look for. So, instead of a few tasks done one by one, I was sometimes doing several at once.

As I was proofreading the puddles blog upon returning to Colorado, I started wondering if the puddle simply had been left behind from the previous week’s rains, and that salt may have kept the puddle from freezing.

I had the opportunity to check this last week, on a second trip to Missouri. Again, there had been rain a few days before I arrived. And again, there was a puddle in the same place. But this time I could see clearly that water was flowing into the puddle (and other places along the road) from gaps in the curb as well as some in the street. You can see this in Figures 11 and 12.

Figure 11. A new puddle (photographed 19 March) at the same location of the one photographed in February, in Columbia, Missouri. Note that water is leaking through a gap in the curb as well as part of the crack.

I also discovered that the puddle was not in a dip in the road, as I had suspected earlier, but it was located in a place the road was nearly horizontal (okay, maybe a very shallow drip): There was actually some flow downhill toward the lowest spot, where water drained into a sewer. Finally, I discovered that the puddle is only about 2 meters (6.6 feet) above the lake.

Figure 12. Closeup of the puddle.

There were other puddles along the road, formed from drainage through gaps in the curb and sometimes gaps in the pavement of the road (most of the cracks in the roadbed are sealed with tar).

After a few days with temperatures rising to around 15 degrees Celsius (59 degrees Fahrenheit, the puddle finally disappeared. Where the water was, a white stain on the road revealed that salt had collected there; and there was drier soil carried along with the water feeding the puddle.

Another day with no puddles convinced me that the pipe connecting the fire hydrants (see earlier parts of this blog) was not leaking.

So, with a little extra data I was able to confirm the hypothesis that the puddle was being fed by subsurface water flowing at least through a gap in the curb (which is ~15 centimeters or 6 inches high) and possibly the crack in the road. Salt clearly also played a role in keeping the water from freezing.

I also found out something else. My brother and sister-in-law’s house was heated and cooled by pumping groundwater up to the house. Remember, the temperature 30 meters (100 feet) down – or even 10 meters (30 feet) down – is close to the average temperature for the whole year (in Columbia, about 13 degrees Celsius or 55 degrees Fahrenheit). So the water pumped up to the surface in the summer will be much cooler than the air temperature, and thus can be used to cool the house. In the winter, the ground water is almost always warmer than the house, so it can be pumped up to warm the house.

But remember – the temperature of the ground water – and the average temperature – is about 13 degrees Celsius (55 degrees Fahrenheit). That’s not warm enough to heat the house in winter, so another method is needed to bring the temperature up from 13 degrees to a more comfortable 20 degrees Celsius (68 degrees Fahrenheit) or so.

Next time: how the investigation of this puddle illustrates the inquiry process – or the “scientific method.”

Figure 8. Me enjoying the relatively cool temperatures in a hole. The shade helped, too! Photo by Lorrie McWhinny.

Figure 9 shows how the temperature varied beneath a winter wheat field in south-central Kansas during the late spring-early summer of 2002. The temperature 7.5 centimeters below the surface (blue curve) reaches a maximum in the early afternoon, with the peaks slightly later as you go to lower levels. Note that the daytime temperature at 7.5 centimeters below the surface is warmer than that at 15 centimeters, and so on, with the coolest temperatures at 80 centimeters below the surface.

Figure 9. Soil temperature as a function of day of year for a winter-wheat site in south-central Kansas. The distances in cm (centimeters) indicate how far below the ground surface the measurement is being taken. Day 138 is 18 May, Day 150 is 30 May, Day 180 is 29 June. All data for 2002. Date collected and processed by Professor Richard Cuenca, Oregon State University. The maxima in the blue curve occur in the early afternoon.

These data, which are fairly typical, are consistent with our impression that the soil is usually cooler than the surface for most of the day during summertime. (The cooler surface temperatures on some days appear to be related to rainfall.)

The surface temperature for the same site appears in figure 10. Notice how the surface temperature peaks during the day about five degrees higher than at 7.5 centimeters during the first part of the data record, and then 10-15 degrees higher than the temperature at 7.5 centimeters late in the record. The change is related to cooling of the winter wheat (the sensor is measuring the temperature of the winter wheat) due to evapotranspiration during the first part of the record. Once the winter wheat stops growing and becomes golden, transpiration is no longer happening and the dry wheat and then the wheat stubble and ground surface are strongly heated by the sun.

Figure 10. For same site as Figure 4, except for surface temperature. Note that the wheat becomes golden (senescent, stops growing, is almost ready to harvest) around Day 150 (30 May).

The same happens to the bare ground at other sites – the surface is much warmer than the temperature 7.5 cm below the surface.
Have you been in a cave in the summertime? Caves, being farther from the surface, are even cooler. At the Devil’s Icebox, a cave not far from where I am writing this blog in Columbia, Missouri, the temperature stays at about 56°F (13°C) all year, even though the average summertime high temperature in Columbia is in the upper eighties (around 30° Celsius) and the average wintertime low temperature here is in the mid-teens (around -8° C).

So in the summer, the ground gets cooler as you dig down, — at least through the upper few meters. In the winter, the ground gets warmer farther down. And in caves, the temperature doesn’t change much at all. In fact, I once read that a cave temperature is a good first guess of the average above-ground air temperature at the cave’s location.

Similarly, people in many countries take advantage of the cool below-ground temperatures too store food during the hot summer. Also, some people take advantage of the temperature several feet below the surface to heat their homes in the winter and cool their homes in the summer.