In this series, educator Deb Greene walks us through some of the science on the ship. She explores the practices of science and how they fit in with the Next Generation Science Standards. Deb has taught and been involved in curriculum development in both the public and private sector for over 35 years. She currently works in Curriculum and Instruction for the Anchorage School District in Alaska.
Part 2: What scientists are asking
Erin Guillory, an undergraduate in Miguel Goñi’s lab sums it up nicely, “You can read about things in books, but it’s about asking questions that makes science come alive. Also, being out on the water collecting the data that you are going to analyze… that is inspirational. It’s about doing science.”
Chief Scientist Dr. Laurie Juranek from Oregon State University, College of Earth, Ocean, and Atmospheric Sciences (CEOAS) heads up this scientific voyage. Her impetus behind putting together this National Science Foundation (NSF) funded proposal and team of scientists came from an interest in the changing environmental conditions seen in the Arctic.
Key to deciding on what questions to ask, the team of scientists looked at what they knew. Scientific data collected overs several decades shows that the amount of sea ice covering the Arctic regions is declining each summer. The planet is reaching historic low levels of ice. This may be a contributing factor to an increase in wave action along coastal regions. Waves may cause coastal erosion, but may they also do something that increases the productivity of the area?
Every year there is a seasonal fluctuation in sea ice. In recent decades though, there have been increasingly low levels of ice in the late summer months before the ocean begins to refreeze. With a decrease in sea ice, more water is exposed. That means that the possibility of more phytoplankton (tiny little plants that are able to make their food though photosynthesis) may be getting enough sunlight to increase the biomass at the bottom of the food chain. This may in turn increase the food supply for more complex organisms such as krill that are food for whales, and fish that make up a large part of the walrus and seal diets because more sunlight is able to penetrate the water that was once covered by ice. This can only happen though if appropriate nutrients (think fertilizers) are available and circulating into the aquatic system. Typically, in the late summer, nutrients available to microorganisms are used up. Following that train of thinking, scientists are asking, “Is it possible that nutrients lower in the water column are stirred up and made available because of more wind/storms are creating greater circulation of the water or can these tiny organisms actually make their own fertilizer and metabolize nitrogen stirred up in the system?”
Last year data collected showed that there are specific areas in the Arctic that are more biologically productive. There is a question as to what factors may be involved in this increased productivity. Dr. Juranek’s motivation for putting together this scientific voyage filters down to: Is there late season productivity in the Arctic and if so, what is the impact of sea ice decline on productivity at the base of the food chain?
Returning to the Arctic this year and sampling at many of the same locations as last year, scientists from all teams are able to look at how things are similar or different from last year to this year.
The Goñi Lab
Dr. Miguel Goñi’s lab at Oregon State University, College of Earth, Ocean, and Atmospheric Sciences (CEOAS) bases their research on chemical and physical aspects of the marine environment. The scientific community has demonstrated that sediments cover the ocean floor. In the Bering Sea and specifically on Hannah Shoal, these sediments remain from the Bering Land Bridge that connected what is now Russia and Alaska tens of thousands of years ago, as well as through deposition and scouring during glacial and interglacial time periods – a cycle of roughly 100 thousand years.
The planet, due to this constant fluctuations in the Earth’s orbital shape as it travels around the sun, has gone through many such cycles in it’s 4.5 billion year history. But glaciers have not always been a feature on Earth. Conditions must be favorable for the accumulation and retention of ice. A record of this cyclical response to fluctuating climatic conditions allows scientists to trace ice back approximately 4 cycles or 400 thousand years.
In the Chukchi Sea, Barrow Canyon parallels the coast from approximately Wainwright to Barrow. This marine canyon and underwater deltas were geologically formed during glacial periods as freshwater rivers created huge amounts of runoff from what is now the North Slope Borough of Alaska.
What makes this a complex cycle between the physical and biological world is that the fluctuations in climatic conditions and therefore in the environment impacts the amount of CO2 in the atmosphere. This is impacted by a number of factors including organisms present or absent on Earth, the position of the continents, and the shape of the orbital path of the planet around the sun. These, and other influences contribute to CO2 levels. If microorganisms are present that can utilize this CO2 and respire oxygen, then potentially excess carbon can reach the seafloor bottom and be buried, effectively pulling the carbon out of the system. It stays in this buried state, effectively pulling carbon out of the system unless it is recovered as organic coal/ oil or brought back to the surface through volcanic activity.
The conditions of the Earth and climate have to do with how much CO2 is in the atmosphere. Before large terrestrial animals roamed the planet and plants lived on the land and in the seas, CO2 was broken down in the photosynthetic process and oxygen was the byproduct. As animals that used oxygen and gave off CO2 as their waste evolved, levels of oxygen dropped and CO2 levels have risen.
It is a complex system and as tectonic movement has repositioned land masses at or near polar regions when the Earth has been on a more elliptical orbit, the planet is poised for a temperature drop. Snow and glaciers cover polar regions near or on land masses. There is a correlation that during these glacial time periods, less CO2 is found in the atmosphere and carbon is locked in the Earth’s crust.
Now, due to the tilt of the planet and our almost circular orbital path, the planet is experiencing a non-glacial time period (the most recent ice age ending about 20,000 years ago). Additionally, humans now play a role in releasing CO2 into the atmosphere by burning fossil fuels that have been storing large quantities of organic carbon for millions of years.
Although we need CO2 in our atmosphere to provide an insulative shield from the cosmos, (or else Earth would be similar to its sister planet Mars), too much atmospheric CO2 makes a hotter world. This climatic adjustment may have driven and will drive the extinction of many species.
Data shows that in the last 150 years, since the beginning of the industrial revolution, the CO2 balance in the Earth’s atmosphere has accelerated the rate at which the amount of CO2 released into the atmosphere. This is at a rate that the Earth has never experienced before. We can find clues in ocean sediments.
Have you ever looked at sediments from the ocean? Some sediment is sandy while others seem to have a lot of clay in them. Also, between the grey muck ribbons of black are sometimes seen running through the layers. This black stuff is iron sulfide. Iron sulfides signal that oxygen has run out of the system, which is actually positive! It indicates that microorganisms in the water column are taking up CO2, using it, and releasing oxygen as a byproduct. It indicates that oxygen is not found in deeper sediments indicating a biologically productive system.
Also, iron is an essential micronutrient needed to support life. If iron is present in seafloor sediments and can get stirred up by turbulence to make it available to microorganisms, then this would be a defining piece of the puzzle supporting late season productivity on the Arctic.
Within the sediments Goñi’s team is also looking for plankton, organic layers of once living things. These are the result of plankton in the ocean dying and sinking to the bottom. These create a record of the recent past. They show when the area was most productive. Scientists for decades have been recording evidence of early season blooms of plankton. In the past scientists thought that early summer organisms used up all the nutrients thus stifling late season blooms. But data shows that the Arctic is experiencing late season blooms. Now they have to figure out where these nutrients are coming from to support this type of biotic activity.
So, Dr. Goñi is looking at particle abundance in the water column and in seafloor sediments. By measuring the organic matter (the amount of carbon) in the water and sediments, the question the Goñi lab is focused on is, “Within the water column, how much organic matter is produced?”
Goñi’s sediment samples will show a record on the scale of seasonal fluctuations in productivity for approximately the last hundred years. It will provide a window into how productive the Arctic is and has been over a larger time scale than what the other researchers are investigating. This is because in this part of the Arctic, sediments deposit at a rate of a few millimeters a year. He is looking for patterns in the sediments as a way to confirm areas of seasonal high/low productivity in the Arctic and is looking to provide evidence on, “ is the Arctic going to become more productive for phytoplankton than in the past?” If the amount of biomass and therefore carbon in sediments can be quantified, this will indicate if carbon is being stored in the sediments. On the contrary, if carbon is not present then it is actively playing a role in the carbon cycle and continuing to contribute to CO2 levels.
The interesting thing about studying sediment deposits is that it allows scientists to look into the past much farther back than recorded human history. By looking at sediments Goñi can start recognizing how Earth has changed for a lot of reasons including the evolution of plants and their uptake of CO2; the evolution of terrestrial animals and the resulting more CO2 being released; the role volcanism has played in CO2; the distribution of land masses; differences in solar insulation; and the cause of glacial/interglacial periods. It is a very complex system. There are things that have happened in the past that will happen again including an increase in CO2. Marine sediments allow us to look at the last few hundred years and interpret the clues.
A Lesson in sediments:
Every inch of earth has a unique story to tell. Giving students the opportunity to investigate what lies below the surface of any area provides an opening to ask questions about the geological and biological past of an area. Coring soil from the school grounds – even if they have been backfilled- tells a short story (how deep is the active layer, what living organisms can we find here, characteristics of the soil, how much top soil was put on top of fill?).
Looking around the natural areas close to school though can give a better view into the past. Can we find evidence of glaciation in soil deposits? What are clues that this area has ad major earthquake activity? Can we document an influx of sea water through sediment deposits along Turnagain Arm and around Girdwood that would indicate a change in altitude of land mass due to tectonic activity? If we can we find Bootleggers Cove sediments out on the tidal flats along the Coastal Trail what evidence do we have suggesting catastrophic events?
Giving students the tools to ask questions, defining what they are looking for, planning and carrying out investigations, interpreting data, and constructing explanations allows students to engage fully in the scientific process.