Be your own wolf

If your high school asked you to come back and be the guest speaker at commencement, what would you say?  Well, here’s what I came up with for Marion Center Area High School’s class of 2014:

Good evening, Marion Center! Congratulations, Class of 2014! It is such an honor to be here, thank you for inviting me to speak to you at this momentous occasion.

Ever since Mr. Betts {environmental science teacher} asked me to be your commencement speaker back in January, I’ve been thinking about you all and this night and what it means to you. And wondering, what can I share with you that can help you find your way, what profound piece of {Julia Child voice:} wisdom can I pontificate that will enlighten and inspire you? {regular voice:} But then I thought about when I sat where you are sitting twelve years ago. And I realized, two things: first, you and I were in fact enrolled at Marion Center Area School District at the same time. It’s true—you might have been kindergarteners, and me a senior, but that still counts for something. And the second thing I realized was, I have no clue who the commencement speaker was when I graduated high school OR college, let alone what either of them said. So I decided I didn’t need to worry about {Julia Child voice} pontificating and enlightening and instead I’m going to briefly (we all know why we’re really here, {whisper} they’re graduating) explain the one thing that I’ve kinda figured out that might help you.

I could paraphrase what I’m about to explain by simply saying “follow your hearts” or “shoot for the stars”. Those are nice, but they’re so over-used they have essentially lost all meaning, right? So instead I offer this 2 step plan (oh and no need to take notes, folks, because there won’t be a test, SWEET!) :

1) find your passion, and

2) follow it, but really, scratch that, don’t just follow it—chase it down like a wolf on the hunt.

Neither step is easy, my young grasshoppers. For the first step, some of you may have already found your passion, and that’s great. For others, it may take several more years to find your passion, and you, like me, might have to try a few different things along the way.

For me to find my passion, it was like being on a scavenger hunt. I would push myself outside of my comfort zone to go to new places, participate in new experiences, interact with people I didn’t know. The first such experience that helped me really see the direction my passion was headed, was in one of Mr. Betts’ classes. I would come home from school and talk about this class so much that my parents still remember to this day that class’s name—Web of Life. And with each new experience like that, there would be some element, sometimes big, sometimes small, that would really speak to the essence of ME, that would light up something inside me, and I’d say to myself “Oh that’s fascinating—I can do that for a living—whoa?!” These would be things like: the joy of working with brilliant people who are also passionate about what they do, or realizing that I want a job that allows me to work outside.

Along my journey I’d continually ask myself this question, “in 10, 20, 30, years down the road, when I wake up in the morning and it’s dark and cold outside, will I be excited to get up and do what I do?” Similarly, at the end of the day will I be pleased with the tiny contribution to the world I’ve made that day, that year, at the end of those 10, 20, 30 years? If the answer is yes, then you are on the right track.

I’ve continued to amass these clues along my grand scavenger hunt to find my specific passion. And now I’m in step 2: chase your passion like a wolf on the hunt. At first I was just a wee wolf leaving the den for the first time and I didn’t really know what I was hunting or the best way to catch it. And at first I wasn’t very hungry for it. But with each new experience my ability to see my prey became sharper. Now, I am truly hungry to know

  • how the availability of water for farmers around the world is being affected by climate change,
  • how to manage groundwater—a shared resource that is vital to farmers’ livelihoods as well as the health of streams and rivers, and
  • how carbon and nitrogen cycles are affected by these changes in water use.

This is what fascinates me and gets me excited to get up in the morning and get to work.

Twelve years ago if a palm reader had told me that this was my passion I would have said, “GIRL, YOU CRAZY!” I had no idea that this is what I wanted to do with my life.  These passions—agriculture, water, climate change—might sound really specific or, perhaps, odd but through my myriad experiences trying different things I have found that this hunt, this prey, this area of research brings together a constellation of all the different elements of what I want in my career: it has to do with water in the environment, the production of food, using science to help society, and I get to spend a lot of time working outside. This is my recipe, what are the ingredients to your recipe?

I’m not hunting this prey, this elk, if you will, by myself, I am building my own pack of wolves who help me chase my passion, I have my graduate school advisor and other scientists and mentors I’ve met along my journey, and I’ve always had my mom and dad helping me too. I even have my own little wolf, my dog, Bowie. Who will be a member of your pack? Who will help you chase your passion and who is holding you back?

Wolf packs hunt by running their prey down to exhaustion. Maybe that’s where the phrase “dogged determination” comes from. It ain’t easy and it ain’t pretty. You’re hungry, thirsty, you get confused, there’s a snowstorm, you’re exhausted, you trip and fall, but you get… back… up. I don’t catch my prey every time, I’ve fallen down and gone hungry many a night (figuratively speaking, don’t worry, mom & dad!). You have to realize that failure happens to everyone. PERIOD. If you’re afraid of failing at something, think through what’s really, really the worst that could happen?

A) I fail and get up and try again or try something else OR

B) I don’t try and never know what I could have done but, hey, at least I didn’t fail?

I’ll take A any day of the week. Failure is part of the whole process. You have to fail to find out what you can’t do, what you don’t like to do, to build up resilience & strength, to feel empathy for others, and most importantly to learn from your mistakes.

If I had taken all the times I failed in high school as an indication of what I was capable of, I would not be where I am today. Folks, I wasn’t on the homecoming court, I didn’t go to the prom, and I didn’t get in to my dream college.   I took stock of my failures and my assets, and pursued my passion for science relentlessly. Luckily, being a great scientist doesn’t mean you have to win a beauty pageant or get asked on a date. Instead, I’ve travelled the world and I work with top-notch scientists. I say this not to brag, but to show you how to embrace failure as an opportunity to learn and push on.

Another obstacle, besides fear of failure, that might get in the way of chasing your passion is money, right? You’re probably already thinking to yourself, “Let’s get real, Bonnie. We can’t all run off chasing our dreams.” Well, my ability to follow my passions was in no way a product of family wealth. This is something I feel really strongly about and maybe is the most important thing I have to say to you. I refused, refused to let the income bracket I was born into limit my future opportunities. When I decided I wanted to study abroad during college in order to hunt my passions, I took out loans and, later found internships and scholarships that paid me:

  • to go on safari in Kenya and see with my own eyes elephants, wildebeests, lions and all the other wild creatures of the African savannah;
  • to look for the disappearing tree frogs in a remote, mountainous cloud forest in Panama;
  • to sail from Mexico to Tahiti on a sailing ship doing oceanographic research;

I took a risk by going into debt, but those risks have paid off because now I’m doing what I love AND getting paid to get a PhD. I also don’t let the need to earn buckets of money limit what I do. I do not believe that making more and more money brings more and more happiness. Sure, it certainly helps to a point but then it just levels off. Often your passion and earning buckets of money are not the same career. In fact following my passion involved going into debt, like I said. But I also have chosen not to start a family until I’m ready so that I have the time and financial freedom to chase my passion now. This has worked for me, but it may not be what you choose, you have to discover and follow your own path.

In these twelve years since graduating from MC, I’ve found my passion and I’m chasing it wherever it will take me. Now I challenge you to be your own wolf, find your passion and hunt it down. What kind of prey are you hunting, can you see it? Where will your passion take you?

Like I said, you probably won’t remember me or anything I said, but I hope you stay true to yourself and your passion and if you do, you and the world will be all the better for it. Thank you and congratulations.

Flerds -OR- How Durham, NC shaped me into the scientist I am today

A colorful display of fresh veggies at the Durham Farmers Market.

Yes, Durham.  What used to be considered the armpit of “The Triangle” (Raleigh, Chapel Hill, and Durham) has re-gentrified and transmogrified its way into a food-centric, community-minded mecca.  I lived there for five years and fell in love with my neighbors (shout out to my Old West Durham peeps), the community (things like the Durham Literacy CenterSEEDS, and the Scrap Exchange), and the beautiful landscape.  The Durham County Library system has received attention recently for developing a seed library in addition to the stacks of those heavy, paper thingies…oh yeah, books (just kidding, I love real books).  Library patrons will be able to sign out a packet of seeds and “return” them by saving seeds from their harvest in the fall.  This epitomizes the culture of Durham that helped spark my interest in food as an ecologist and a human being.  That and I’ve been feeling a little homesick for it lately, so I decided to tell you all about why it’s so special.

When I expressed this interest in the ecology of agriculture to an ecologist at Duke University, she suggested trying out farming for real.  She suggested getting in touch with Ben Bergmann and Noah Ranells at Fickle Creek Farm.  Little did I know, Ben and Noah are founding members of the Durham Farmers Market; their eggs sell like hot-cakes every Saturday morning; and that I’d start eating meat again after working with them.  I was working full time in an ecology lab at Duke while I lived in Durham (also an invaluable experience shaping me as the scientist I am today), and I worked part time on the farm for one year.  Not only are Ben and Noah great farmers, local leaders in sustainable agriculture and mentors to young farmers getting started, but they are also scientists.  Both have a PhD from NC State University: Ben in horticulture and Noah in soil science.  Working at Fickle Creek Farm was a turning point in my development as an ecologist.  Their passion for and knowledge of sustainable farming from the microbial scale to the landscape scale, from the humane treatment of animals to food justice issues in our own backyard,  lit the way for me to find my path to graduate school.  Rather than focus my research on sustainable farming, however, I’ve decided to focus on conventional row-crop systems, since this system of food production isn’t going away anytime soon and it has the largest environmental impacts.  But the bucolic memories of “flerds” (flocks of sheep + herds of cattle), egg-mobiles (moveable chicken coops), and picking vegetables by hand are never far from mind.

Noah would often use me as a selling point to vegetarians at the farmers’ market, saying I’m a Fickle-Creek-Farm-etarian, because I felt better about eating a hamburger from Fickle Creek Farm that was grass fed and finished and humanely slaughtered, than I do about eating a tofu-burger made of soybeans from the deforested Amazon.  And with locally grass fed and finished beef, the carbon footprint of the hamburger actually comes out a little ahead of the tofu-burger.  Every Friday Ben cooks a luxurious meal for the staff made with plants and animals from the farm.  This is where I got a taste for things like spicy pickled okra, cow tongue, and rocky mountain oysters.  As a budding biogeochemist, I particularly enjoyed learning first hand about how raising animals along with vegetables is necessary for closing nutrient cycles.


Dr. Noah Ranells, co-owner of Fickle Creek Farm, and me at the Durham Farmers Market.

I also got to see how Ben and Noah engage with the public.  I learned a lot about patience and grace from Noah dealing with customers at the farmers market.  Even though it’s a crunchy, hippie farmers market vendors we sometimes get treated like we work at a department store.  I also learned a lot by joining Ben when he led groups of the public around the farm.  There are a lot of difficult and controversial issues related to how we produce food, and Ben provided a nice balance by explaining both the ugly side of modern food production with the hopeful side of sustainable practices.  And I think he did that not to be simply provocative, but to lead people to question their own choices and role in the big picture and provide them with potential solutions.  If you can only provide one half of that equation, you’re doing the public a disservice.  I think one trick to good outreach is to provide both.  I still think back on these walks with Ben when I do public outreach for my own research.

When it comes to Fickle Creek Farm and Durham, NC I could wax on all night and into the wee hours of the morning telling you about all the coincidences that happened there that got me here.  And then I could talk some more about the beautiful natural history of the area, i.e. the Eno River was my church.  But I’ll stop here because I’m hungry (I can’t imagine why).  So if you’re ever near Durham, it’s definitely worth a visit.  Bring a hungry belly, some re-usable shopping bags, and your farm boots.

Note: for more information on Fickle Creek Farm (including their Bed and Breakfast) go to

The Eno River in full bloom.

The Eno River in full bloom.

Downtown Durham 39

A “ghost sign” on the side of an old tobacco warehouse. Nobody in Durham endorses tobacco use, but the growing and selling of it is definitely a part of the heritage.


Rural NC abounds with beautiful old barns and out buildings.

Rural NC abounds with beautiful old barns and out buildings.

How does “sound science” sound to you?

Endangered species: Gray wolf, Manatee, Whooping Crane, Unmuzzled Scientist

By John Klossner for the Union of Concerned Scientists newsletter.

The term “sound science” might sound like a harmless or even comforting phrase, but lurking behind it is a hidden agenda.  “Sound science” in today’s politics means research that supports big business, often with results that dismiss the need for federal regulation of products, contaminants or waste streams.  There was even a sound-science bill that nearly made it into this year’s farm bill, which would have limited federal regulators to using “sound science”–that which is “experimental, empirical, quantifiable, and reproducible”–meaning no use of climate models or results from singular events like natural disasters or qualitative studies, for example.  Science policy expert, Colin Macilwain, explains:

‘Sound science’ is…science that big business knows it can trust. In its name, businesses that sell contentious products are working night-and-day to deflect rules and regulations by exploiting a schoolboy image of science to make their case.  And whatever the issue — nuclear power, pesticides, pharmaceuticals, alcohol, oil or coal — they take the basic game plan from the lessons learned by the tobacco industry over the past twenty years.

You can read the rest of Macilwain’s recent column in the journal Nature called “Beware of back room deals in the name of ‘science'” by clicking here.



Ag news roundup: the 2014 Farm Bill, antibiotics & obesity, and sustainable livestock production


President Obama signed the 2014 Farm Bill into law at my school, Michigan State University. He is joined by Sen. & MSU alum Debbie Stabenow (third from left) and Sen. Carl Levin (far left).  Photo by Kurt Stepnitz

…My senator, Debbie Stabenow (D-MI), admirably led the charge in developing the 2014 Farm Bill, which reflects Americans’ changing taste for more sustainably raised food.  It brings new crop insurance protections to tart cherry growers (and other fruit and veggie growers) who formerly did not qualify for the insurance.  (Aside: Dried tart cherries, a Michigan specialty, have played an important role in helping me stave off the winter blues!)  Subsidies for traditional commodities were cut by almost 1/3 while support for programs to help farmers transition from conventional to organic more than doubled.  Read more about the new Farm Bill and Sen. Stabenow’s role in developing it in this New York Times article by Jennifer Steinhauer.

…It’s not news that it is common practice in commercial livestock production to feed antibiotics to make the animals gain weight quickly or that these antibiotics get into our soils and streams.  But this article adds a surprising new layer to the story of industrial use of antibiotics: What if the over-use of antibiotics in ourselves has contributed to the obesity epidemic in the U.S.?  The author, Pagan Kennedy, discusses research on the human microbiome that shows some interesting results, but the field of human microbiome research is in its infancy.  To learn more about the human microbiome, check out this fun, 5 minute, animated video from NPR–which has done a whole series of reports recently on the human microbiome.

…Finally, a recent comment piece in the journal Nature by Mark Eisler and others offers eight suggestions for raising livestock more sustainably.  This is really  important because the rising number of people on Earth whose rising standard of living allows them to eat more meat presents risks to food security and the environment.  (I’m not trying to insinuate that people in developing countries should not enjoy the same standard of living as some of us in the U.S.–I’m just pointing to the sustainability issues involved in producing that much meat.)  Every year, we feed approximately one billion tons of agriculturally grown grains to livestock; grains which otherwise could feed about half the world’s current population for a year.  The Nature article points to how livestock can be used to complement rather than rival crop production with some interesting suggestions like feeding livestock less human food and raising regionally appropriate livestock.  Instead of reading the comment piece, you can listen to the podcast while cooking up your next meal featuring locally raised meat.  *This article is open, so even if you don’t have full access to Nature you should still be able to open the article through the link at the beginning of this article.

Water Hero: Margaret Palmer

The first interaction I ever had with Dr. Palmer was at a science conference where she was the keynote speaker.  During the Q&A, I raised my hand and introduced my question by saying, “Long time listener, first time caller…”  And I suspect the first part, “long time listener”, was an apt description of most of the audience because Palmer has been an influential scientist in stream ecology for many years.  I have been particularly interested in following her recent focus on mountain top removal / valley fill (MTR/VF) coal mining and its effects on headwater streams in southern WV and eastern KY.  Not only does she carry out research quantifying stream ecosystem function responses to MTR/VF, she also testifies as an expert witness in cases involving the coal companies’ environmental impacts.  Last week Science magazine published a news feature profiling Dr. Palmer’s efforts to step beyond the bounds of a traditional academic and toward being a scientist involved in societal issues.  You can learn more about this leading lady scientist by reading the full Science article here: Palmer, Margaret – The mountaintop witness SCIENCE 2014.  You can also see Dr. Palmer’s appearance on “The Colbert Report ” in 2010 here.

Dr. Palmer is a professor of entomology at the University of Maryland and the executive director of the National Socio-Environmental Synthesis Center in Annapolis, MD.

What’s a scientist to do?

As a follow-up to the previous post, I wanted to share an excellent NYTimes article published yesterday that also asks, “What’s a scientist to do?”  but this one is regarding climate change.  Thanks to the AGua reader who passed this along.  Here’s a quote:

If scientists choose not to engage in the public debate, we leave a vacuum that will be filled by those whose agenda is one of short-term self-interest. There is a great cost to society if scientists fail to participate in the larger conversation — if we do not do all we can to ensure that the policy debate is informed by an honest assessment of the risks…This is hardly a radical position. Our Department of Homeland Security has urged citizens to report anything dangerous they witness: “If you see something, say something.” We scientists are citizens, too, and, in climate change, we see a clear and present danger.

And here’s the link to the full article, written by Michael Mann, a professor of meteorology and geoscience at Penn State University.  On a related note, if you haven’t seen the documentary “Chasing Ice” yet, I highly recommend it.  It’s about a scientist-turned-photographer, James Balog, who has dedicated his career and life to documenting climate change in a way that will help people understand it.  His epic and often dangerous mission brings us stunning time-lapse images of melting Arctic glaciers, which really helped me wrap my mind around the daunting scale and speed of the melting ice.  I think it’s a safe bet to say if you’re reading this blog, you want to see this movie.  Here’s the trailer:

Stuck between a rock and a tar ball

Last month Kalamazoo River watchdogs presented startling stories that the river is loaded with tar balls, resulting from the oil spill back in 2010.  As testimonial, videos, and photos emerged online, several fact-checking reporters turned to professor of ecosystem ecology and biogeochemistry, Dr. Stephen K. Hamilton of the Kellogg Biological Station, Michigan State University (and, full disclosure, he’s my graduate advisor).  Faster than I can say “biogeochemistry”, some of Steve’s comments were picked up and mis-quoted on other web sites.  While Steve explained to me how these events unfolded, I was struck by the perplexing conundrum he was in, and what I could learn from it as a young scientist interested in controversial environmental issues.  So in this post I’m going to explore that conundrum, discuss the role of science and scientists in this type of situation, and explain a little about Michigan geology.

The play-by-play

First, watch this quick video to set the stage:

These citizens also sent samples to a lab for analysis, the results of which were interpreted as evidence that Enbridge (the oil company responsible for the spill) secretly used “Corexit”, a paint-thinner-like dispersant to make the floating oil sink to the bottom.  (You may remember the controversy over BP’s use of Corexit in the Deepwater Horizon oil spill).  The thinking for the Kalamazoo River was that this might explain why millions of dollars and several years later, clean up efforts continue to uncover oil submerged in sediments.  This was reported in the Vancouver Observer and The Tyee.

When reporters (including NPR) need a second opinion on anything related to the environmental impacts of the Kalamazoo oil spill, they turn to Steve Hamilton.  He served on the EPA’s science advisory team for the Enbridge cleanup; in fact he was the only independently-funded (non-government, non-Enbridge) scientist on the team.  Additionally, one of his graduate students did work looking at the health of the macro-invertebrate food web after the oil spill, and Steve led a crew studying the re-suspension of oil from disturbed sediments.  So reporters got in touch with Steve for the tar balls story, too.  He pointed out that what the stories call “tar balls” are naturally occurring calcium carbonate rocks (see below for explanation), and that the reported presence of a dispersant chemical was inferred from the presence of 2-Butoxyethanol.  This makes for a weak inference since this substance is commonly found in many household and industrial products, which all end up washed down the drain and eventually in our rivers (along with plenty of other substances like antibiotics, synthetic hormones, and caffeine).

Aye, there’s the rub

Even though the communication with the reporter was written out in an email, the initial version of the Tyee article mis-quoted Steve, saying he was “not surprised that an Alabama lab found compounds used in the oil dispersant Corexit on the carbonate rocks.”  When what he actually wrote was that he “would be incredibly surprised if evidence for dispersant use were found because I do not believe it was ever used on the river” (Steve Hamilton, personal communication).  What he was “not surprised” about was that the analysis indicated the presence of the diluted bitumen (tar sands oil) in these porous rocks, because the spilled oil coated everything it contacted including vegetation along the flooded banks–the river was unfortunately high at the time of the spill making cleanup even more difficult.

So, no tar balls and no Corexit (given the evidence).  When the mis-quoted version appeared online, Steve faced two sticky options:

Option 1 (rock): Clarify your position to set the record is straight.  But saying that there are no tar balls and that Enbridge did not use any secret chemicals (given the evidence) may be seen by some as defending the big oil company.

Option 2 (hard place): Don’t say anything, ruffle fewer feathers; but you would have to live with the face that you knew better and did not speak up.  While the record shows you were using poor judgment given the evidence.  This may come back to haunt you.

What’s a scientist to do?

Dr. Stephen K. Hamilton is a professor of ecosystem ecology and biogeochemistry at the MSU Kellogg Biological Station and a Michigan native. Photo:

As you may have already pieced together, Steve contacted the author of the Tyee story and clarified his statement–read the corrected version here.  The story was corrected within 12 hours of its initial posting, but several other websites picked up the original version and still carry it now.  Citizens’ observations and concerns are an important part of society’s conversation about environmental issues.  So scientists encourage people to keep an eye out and speak up when they notice something.  They are experts of their own lives, land, and nearby water bodies.  But in today’s age of blogs and YouTube, unsubstantiated evidence can “go viral” and be presented as fact in sloppy reporting (here is a particularly poor example of the tar ball story).  In this case, these people did send samples to a chemistry lab for analysis.  Unfortunately, not all chemistry labs were created equal, so just as we weigh a scientists’ statement by his or her apparent objectivity, the same is true for labs.

In the bigger picture, this story might make you wonder, “What is a scientists’ role in environmental controversies?”  Above I suggested that by taking Option 1, Steve might be seen as defending the big oil company.  Defending big oil companies is normally not something that an ecologist wakes up in the morning and hopes to do that day; but sometimes the truth ain’t pretty.  At the end of the day, it’s not appeal, but truth that is the golden rule for scientists.  In difficult situations that can mean putting aside both your personal views on big oil companies and your sympathies for environmentalism.

Michigan really is all it’s chalked up to be

Now let’s talk about how those (non-tar ball) rocks got to be in the Kalamazoo River–they can also be found in lots of other lakes and streams in the area.  Back in the day (that is, about 400 million years ago) before the Great Lakes, before Pangaea, when the equator crossed the Hudson Bay and bony fish were the new thing, what is now southern Ontario was marine sediment in the Panthalassic Ocean.  (Don’t worry, you won’t be quizzed on that.)  Over millions of years, these Ontario sediments built up vast quantities of calcium carbonate.  How?  Lots of marine organisms take calcium and bi-carbonate ions from sea water and form calcium carbonate, which they use to build hard structures like shells.  (We use calcium phosphate to make bones, our hard structures.)  For example:

Coccolithophore species: Emiliania huxleyi type A.  Photo:

Coccolithophore species: Emiliania huxleyi type A. Photo:

coral reefs, which would have thrived in these warm, equatorial waters,

–some mollusks (and most mollusk larvae) like the chambered nautilus and oysters,

coccolithophores–a group of super important marine phytoplankton (algae), and

tube-building marine annelid worms.

All of these calcium carbonate skeletons piled up, eventually forming limestone, and then during the last ice age (about 10,000 years ago) the glaciers moved these sediments around–delivering them to Michigan.  This is how Petoskey stones (fossil corals adored by Michigan beach combers) arrived.  So in Michigan, above our bedrock, we have a thick layer (~200 feet in places) of calcium carbonate mixed with glacial sediments (sand and gravel).  This limestone is the matrix for our groundwater and explains why groundwater is “hard”–a lot of calcium tends to build up on Michigander’s coffee pots.  This calcium carbonate gets carried into streams and rivers, where it falls out of solution, and can build up into layered, porous, chalky (literally) deposits.  Who knew those crusty rocks lying around the Kalamazoo River bed were so cool?  Oceans!  Corals!  Glaciers!  Oh my!

Below is a photo of a calcium carbonate rock found on the shore of Lake Michigan near Charlevoix.  It has been turned on it’s side and the black part was sitting in the black spot to its left.  The surprising black color is probably the indirect result of bacteria munching on organic material in the absence of oxygen, such as you might encounter underneath a rock.  As you and I breathe out CO2, some of these bacteria breathe out hydrogen sulfide.  When this gas meets reduced (ferrous) iron, iron sulfide (the black stuff) precipitates out of solution–sometimes this can be found inside water pipes.  I can’t do that, can you?  Microbes rule!

Photo by Steve Hamilton.

A naturally occurring calcium carbonate rock, with black iron sulfide precipitates resulting from microbial activity.  Photo by Steve Hamilton.

For more information on actual tar balls, check out this fact sheet from NOAA.


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