in2science #6

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Press Release

New study reveals that leaves can temporarily store harmful mercury.

Read the press release: Forests significantly influence the global mercury cycle

Institute for Coastal Research

Exploring the vast expanse of science: Johannes Bieser

The mercury expert

Dr Johannes Bieser

Graphic: iStock_wetcake, photo: HZG/Christian Schmid

Dr Johannes Bieser works on matter transport and ecosystem dynamics at the Institute of Coastal Research

Johannes Bieser has a passion for science. That much is immediately obvious: “Aristotle, Gottfried Wilhelm Leibniz, Leonardo da Vinci – I’ve always been fascinated by the great polymaths, even as a child,” he explains; they knew so much, were well versed in many different fields. “That’s just not possible today; as a society, we’ve accumulated far too much knowledge and information for it.” Nevertheless, Bieser tries to connect as many different fields of research as possible in his work.

Johannes Bieser is originally from a small town in the Black Forest. After getting his Abitur (the German equivalent of A-levels), he really wanted to see what life was like in the big city – so he moved to Hamburg to complete his compulsory civilian service. “To me, it was just the coolest big city in Germany,” he says with a laugh. That he would be permanently living there with his family many years later is something he would not have guessed at the time.

Deciding what he would study at university was a huge challenge for him: from molecular biology to philosophy, to music – he considered it all. Eventually this young man from the Black Forest with many interests decided to go to the Leuphana University of Lüneburg and study environmental science, a field that combines several disciplines for him:

“To me, studying environmental science promised a chance to explore the natural sciences in a way that applied to society and policy.”

The 35-year-old first came into contact with HZG while still a university student. In 2005, Ralf Ebinghaus, head of the environmental chemistry department at HZG and professor at the university in Lüneburg, suggested he do an internship in Geesthacht. It was during this internship that Bieser discovered his love of computer models. “I did some programming as a kid, when my brother and I built networks together – but I forgot just how much fun I had doing that sort of thing.” He went on to complete his diploma thesis and to earn his doctorate at HZG.

His dissertation was primarily concerned with establishing an emissions model for Europe. In order to determine where certain pollutants come from, scientists model them in temporally and spatially high resolution, making use of a wide variety of datasets. They then piece it all together like a puzzle, superimposing a grid over a map and collecting data for each cell in the grid. “For instance, if we know how much fuel a country consumes, where agriculture is being done, and how big certain forests are, we’re able to merge all this data and much more.”

The model programmed by Bieser, enables him to change individual parameters. He can calculate what would happen if we were to drive less or what the effects are when forests are cleared or the meat consumption declines. For him, the model itself is just a tool that allows him to make predictions. His actual research interests, however, lie in the transport and transformation of pollutants in the environment. In his doctoral dissertation, the researcher applied his model to one very specific pollutant: benzo[a]pyrene, a carcinogenic pollutant that is primarily formed by wood combustion.

Today, the environmental scientist mostly occupies himself with studying his favourite element: mercury. Mercury is a unique element – a heavy metal that is four times heavier than iron, yet it naturally occurs in gaseous form in the atmosphere. It’s also highly toxic and tends to accumulate in the food chain as methylmercury. “Its chemical properties make it unique – the way I see it, it should get its own category in the periodic table. Also, there isn’t a thing on earth that doesn’t have mercury in it, at least in extremely small quantities,” gushes Bieser. According to him, this is precisely why it’s so exciting to study how it’s distributed. Since the element cannot be broken down and forms very few stable bonds, anthropogenic mercury emissions remain in the system for up to ten thousand years. In the last 150 years, the quantity of mercury in the air and water has increased fivefold. The way this works, in the oceans in particular, remains largely unexplored. “New measuring techniques have allowed us to obtain data, without which we could only speculate until now. Research into the distribution of methylmercury has only just begun,” says Bieser.

Even while at his home in Sülldorf, on the outskirts of Hamburg, where he lives with his wife and their two daughters, he often continues to engage in his research.

“If science isn’t one of your hobbies, then you’re no real scientist.”

At times, he immerses himself completely in his work while he’s there. “Sometimes I just can’t help it,” he says with a smirk. “But at our farmhouse with our cats, two dogs, two horses, and the chicken, there are enough things to distract me – plenty of physical labour in the outdoors.” His fondness for the environment is apparent in more than just his work – as a family, the Biesers are enthusiastically involved in food sharing. With all of that going on, when Johannes Bieser ever does find some time to himself, he likes to spend it at the piano: “It’s the one activity where I can really let everything else fade away.”

Author: Gesa Seidel (HZG)
Portrait from in2science #6 (June 2018)