Unexpected Biogeochemistry Results, and How They Were Surprisingly Helpful

Molly Peek

Smith College

Sometimes, in field science, things do not go as planned, and you just have to make the best of it. While this is true for all of life at JIRP, this year’s biogeochemistry group received special lessons in planning and adaptation.

This was the first year of the biogeochemistry student research project (BGC for short); we needed to start with an exploratory study. With no prior fieldwork done in the area, we relied on related research to begin our study characterizing the chemistry of supraglacial streams in the ablation zone of the Llewellyn Glacier. Supraglacial streams are melt water streams that run along the top of exposed ice in glacier melt zones. Nutrients from nearby nunataks are blown onto the ice, where supraglacial streams transport them across the glacier, and eventually off the end of the glacier into the downstream fluvial system. We decided to focus our project on alkalinity, which is dissolved inorganic carbon, or bicarbonate, in the water. Bicarbonate can be weathered off rocks through water, and thus is a good starting point in characterizing the chemical makeup of water.

Team BGC crosses from the nunataks to the blue ice of the ablation zone for a day of fieldwork. Photo credit: Auri Clark

Team BGC crosses from the nunataks to the blue ice of the ablation zone for a day of fieldwork. Photo credit: Auri Clark

Team BGC headed down to the blue ice of the Llewellyn Glacier and Camp 26 to investigate alkalinity in the supraglacial streams carving the ice, armed with our relevant literature and our alkalinity titrator (a devise used to measure the concentration of bicarbonate in our water samples). After a long traverse over thin snow and a tricky crevasse field, we arrived to Camp 26 on the Llewellyn ready to take alkalinity measurements on 30 melt water streams. Using clean water sampling strategies, we donned plastic gloves and filled plenty of bottles to bring back to camp for titration, as well as recording measurements and observations on the character of the stream.

Chris Miele measures the dimensions of a supraglacial stream on the Llewellyn Glacier. Photo credit: Annie Zaccarin

Chris Miele measures the dimensions of a supraglacial stream on the Llewellyn Glacier. Photo credit: Annie Zaccarin

Back at camp with fresh samples, we excitedly began titration to test for bicarbonate. To titrate, we added a dark green indicator base to the water sample, followed by drops of acid that react to the base, turning the water bright pink. The number of drops of acid required to turn the water a vibrant pink indicates the alkalinity of the water—the more drops we needed to add, the more alkalinity in the water.

Based on previous research on similar glaciers and the nature of the Llewellyn’s geology, our group expected to find significant amounts of alkalinity in supraglacial streams, especially in those streams with visible debris along their beds.

So, where was all this alkalinity? Adding acid to our samples, we consistently found it only in low levels, with the water turning boldly pink after fewer than 10 drops of the acid, indicating a level of alkalinity that was too close to the error range to be statistically significant.

Did we do something wrong? Checking over our work, we realized that, no, we had done the process correctly; we just had results that were completely unexpected. What now?

We had committed a fatal flaw in science: becoming married to a hypothesis! What can I say, we were excited. Our first response was to laugh for a little while in some frustration, and then we decided to take this as a lesson, but make it a fun one in the end.

A supraglacial stream running over the blue the ice, which our testing showed carries surprisingly low levels of alkalinity. Photo credit: Auri Clark

A supraglacial stream running over the blue the ice, which our testing showed carries surprisingly low levels of alkalinity. Photo credit: Auri Clark

If we didn’t find alkalinity where we predicted, we wondered if we would find it anywhere else. As a group, we decided to use our extra bottles to collect samples from other places around Camp 26 and on our hike off the icefield. We collected water from basal streams found in ice caves and coming out near the terminus of Llewellyn Glacier, and at the Llewellyn Inlet on Atlin Lake.

A meltwater stream running over rock debris near the terminus of the Llewellyn Glacier. Although sampling this stream wasn’t part of our initial fieldwork plan, it proved to have high levels of alkalinity. Photo credit: Auri Clark

A meltwater stream running over rock debris near the terminus of the Llewellyn Glacier. Although sampling this stream wasn’t part of our initial fieldwork plan, it proved to have high levels of alkalinity. Photo credit: Auri Clark

Finally in Atlin, we broke open the alkalinity titrator kit for one final hurrah to test these “fun” (or, more professionally, “exploratory”) samples. Observing the water as we collected samples, most of these sites were more turbid, or cloudy with dissolved particles, than the supraglacial streams had been: a good sign for finding alkalinity derived from bedrock weathering. We added our indicator dye, and apprehensively began to add drops of acid. We started slowly, but became more excited as they passed the statistically significant threshold – we had found alkalinity!

Testing these samples was exciting purely because we found the results we had set our hearts on earlier. Even though we know this is a dangerous trap in which to fall in science, as this experiment proved, it was satisfying to find the sought-after alkalinity. Beyond that, though, these samples allowed us to ask more questions about our study, which we consider a successful outcome in an exploratory study.

Why was there far more alkalinity found in basal streams than in supraglacial streams? Where did the alkalinity in the basal streams come from? How do we characterize the supraglacial streams, knowing they have little bicarbonate? How does this differ from basal streams?

All in all, this year’s biogeochemistry project was a lesson in flexibility. When the route through the crevasse field doesn’t work, try again. When your hypothesis gets a little fuzzy, ask why. A ‘null result’ is still a result, and it allows us to build off the unexpected and ask new questions.