By:
Eleanora
I.
Robbins,
U.S.
Geological
Survey,
956
National
Center,
Reston,
VA
20192
nrobbins@usgs.gov
I work on iron-precipitating bacteria, whether they are forming red iron oxide minerals in neutral pH ground water seeps or yellow iron oxy-sulfate minerals in acidic mine drainage settings. This summer I combined iron bacteria research with my vacation in Greece by visiting the iron embayments of Santorini. These are considered to be a modern analog for Precambrian Iron Formation. I was particularly curious about annual variations in microbial and depositional processes in this marine environment: do the same iron bacteria and same processes act all year round?
The big island of Santorini (left) is one of three remaining walls of the volcano, Thera, that erupted in 1628 BC and wiped out the coastal Minoan Civilization with a massive tsunami (see earlier articles on Thera in WAT ON EARTH; 1995: v.8 (2) and v.9 (1) - Ed.). By the time the Roman naturalist-writer Pliny wrote about this story 1,000 years later, it had been transformed into the myth of Atlantis. The warm Aegean Sea has breached the former caldera and is now called "the lagoon" by the residents. Inside the lagoon are two modern volcanoes, Palea Kameni and Nea Kameni; Nea is still smoking. These volcanoes have hot springs in the numerous embayments around their peripheries. The acidic hot springs are sources of reduced iron and manganese, as well a Periodic Table of other elements to feed the bacteria.
I learned that other microbiologists and geochemists had collected at the hot springs during summer vacations too, but for no longer than a week. Their studies documented the types of iron bacteria present in July, the temperature and locations of hot springs (83¡ C at 40 cm depth in a sediment core), and the trace metal chemistry of the water. One thing that struck me was the high concentration of soluble Mn at the mouths of two embayments (X on map). I was particularly interested in learning about Mn precipitation at these sites because iron bacteria often oxidize Mn.
Plan A was to get a sample every month for a whole year. I decided that an efficient way to accomplish this would be to organize an educational outreach science program and have high school students on Santorini collect the samples. Through the Internet, I found a professor, Dr. Chrysoula Kourtidou-Papadeli, at Aristotle University in Thessoloniki who wanted to participate. In turn, she found a high school science teacher in Santorini who volunteered her students to participate in a real science project.
Professor Chrysoula is an aerospace physiologist who plans on applying our research to space. She wants to learn how to terraform Mars; the first step to raising the oxygen levels on Mars is to learn how to increase oxygen levels within a protective plastic bubble in which scientists can work there. She had read a paper I wrote with my dad in Geomicrobiology in 1991 on the potential for finding fossils of iron bacteria on Mars and realized that she could get new ideas by collaborating in my research on Santorini. Together, we named the expedition JIMES (Joint International Microbiology Expedition to Santorini).
We all converged on Santorini the first week in August, high tourist season. Pilot Chrysoula and her pilot husband, a judge on the Greek Supreme Court, flew in on the university's airplane. The high school teacher on Santorini, Gerasimina Damigou, was ready with five interested 14 and 15 year old students, including her own brilliant daughter, Anna, who spoke the best English. She also brought along her handy engineer husband, Markos.
Our team spent two days in the field, using a rented boat to take us to Palea and Nea volcanoes. While there, we:
- collected red iron bacteria and brown bottom sediment,
- learned that manganese-fixing bacteria and diatoms precipitate Mn oxide on the colorful boat buoys,
- found cyanobacteria clinging to the volcanic boulders,
- discovered macroscopic algae living in an anoxic embayment at Nea, and sadly,
- discovered the embayments are accumulating plastic, wood, and paper trash from Santorini and the other inhabited island.
Professor Chrysoula was really excited about the algae because they have direct application to her Mars research. Mars has volcanoes, water ice, an obvious iron cycle, and presumed hot springs. Mars lacks the algae that are needed to help create enough breathable oxygen inside a bubble from which to launch scientific expeditions. Chrysoula thinks that the algae we found living together with iron bacteria in the poorly oxygenated volcanic hot spring environments in the bays of Santorini's volcanoes, might solve the problem.
The students are collecting samples every month, measuring temperature and pH, and making general observations. More importantly, they are solving real field problems. For example, our bright yellow sample buoy on Palea was cut, perhaps by a recluse who lives there, so we lost the first month's sample. Although Teacher Gerasimina felt terrible about this, she was excited when she realized her students were doing real science. They figured out how to hide the sample collectors so no one but themselves can find the samples.
We knew that winter was going to cause new problems. The boatman we hired in August was the father of one of the students. He helped to choose our Nea location because he realized he probably couldn't get the students to our Palea location when the Bora winds blew in February and March. Who would know that the Bora from Siberia would participate in the study of the iron cycle? I am hoping it also flushes the trash out of the embayments.
We didn't get a December sample because of unexpected (El Nino?) storms. The waves were too high for the small boats, and the big tourist boats are in drydock for repairs in December. Real field conditions! They finally got a sample the first week in January when the sea calmed down, the sun came out, and they found a private boat to take them out.
Because of the presence of a Boatman's Union, it was costing $10/per student, or $50, to get the 5 students out to the sample sites every month. The students went to the Union on their own and explained they were doing a science project that was good for Santorini and Greece; the Union graciously waived the fees. I can't predict if working on a field project for a year is going to turn these students into microbiologists or geochemists. Our real dream is influencing the next generation to think about research on Mars. However, I'll bet the presence of so much trash will at least turn them into environmentally conscious citizens.
As for the rest of us, each month brings something new that requires further research to discover if anyone else has ever reported it before. One current puzzle revolves around our discovery of imbricated rows of gliding diatoms that live in tubes that are easily mistaken for green algal sheaths. How are these siliceous algae dealing with oxygen being generated in their tubes? Furthermore, what silicate mineral will these tube-dwelling diatoms and Mn-precipitating iron bacteria form that will be preserved two billion years in Earth's future?
(This is a really good example of how scientists can interact and educate students in a real world experience. If anyone reading this article has similar examples we would be very pleased to publish them. - Editors).