Guest Blog: Zhengzheng Chen, 2nd year PhD student

Zhengzheng Chen is currently 2nd year PhD student in the Interface Geochemistry research group at GFZ Potsdam. She joined us in November 2020 as a Chinese Scholarship Council (CSC) PhD scholar and will be with us until 2024. Her PhD project focuses on the interaction between iron minerals and organic carbon in Arctic peat soils. Check out her profile here: GFZ Profile | ResearchGate.

Contents of this blog is unaltered and posted as is to preserve the voice and own ideas of Zhengzheng Chen.


It’s been a year and a half since I started my PhD, and I can still remember the nervousness and excitement I felt before I was accepted. At that time, I had only heard that it was a great group. Yiping (a former CSC visiting PhD student in the group) told me that Liane and Jeff had published many really good papers and that and that it would be good to get training from them. Meanwhile, Hongyan said they were very nice, but I had no idea about “very nice”.

I started my PhD at the serious point of the pandemic and was completely clueless about a completely new field; but Liane and Jeff (my PhD supervisors) didn’t take it for granted that I knew a lot. With a “you’re doing a PhD because you don’t know” attitude, they encouraged me to say “I don’t know”, which was considered a shameful thing in my upbringing. There are many things that need to be repeated over and over again to be mastered, but I used to think that I should have grasped and applied it well after being taught once. Here just learning a little bit of something new is rewarding and it’s a great feeling!

Looking back on the year, I seem to have learnt a lot of concepts and methods, but I still can’t be sure to explain the principles and why and how. It makes me feel like what I’ve learnt is a moon in the water, a flower in the mirror. It’s a bit like taking a theorem to solve a math problem, but don’t know how to prove the theorem. Over the past year or so, I have often been shocked by these differences in education and have thought about it.Jeff is one of the most amazing people I have met. He was so patient in the beginning and spent a lot of time with me doing some very simple experiments to help me get started. He can find the paper by just googling the author and title when talking about a particular problem (God knows how much I would love to have that ability!); and he remembered details of my experiments, Ruth and many PhD students in the group (I sometimes can’t even remember). He’s also exceptionally productive, and from the little that I know, he works not only on his own experiments, but also with PhD students, discussing and collaborating with many people, organizing seminars, reviewing manuscripts, applying for projects and funding, and he still has free time to relax! (OMG, it’s so hard for me to write a paragraph for my paper.) Looking at my slow progress, I really wonder if I will be at Jeff’s level by the time I get my PhD. There is a saying that “Blue from indigo plant is deeper than its origin” (meaning that the student surpasses the master), and It’s all very well if I could become light blue.

I sometimes feel that my research is a bit of a pick-me-up, but Jeff and Liane can spot something new in seemingly the same results. Liane and Jeff, who are both confident and passionate about their research, talk about it as if they were showing the whole universe or the history of human development, like a big, big, fascinating story, whereas I can only talk about it in a few dry and boring words. I thought it was a language problem at first, but then same thing when I told my friends in Chinese… I wonder if I will be able to tell a more interesting story as my research progresses. I also feel I need to look back at the development of this research, and there is a widely circulated picture of “what is a PhD” which probably illustrates that what a PhD does is to push a circle outward at the size of a pinpoint, so to make a pinpoint, understanding the background to the subject is also necessary, but it’s such a long and huge thing.

I really feel lucky that I chose to go abroad for my PhD and to be in this group. Whenever I mention to my Chinese friends at the GFZ that my supervisors are Liane and Jeff, they are super jealous of me (which shows that my supervisors are really well known). Before I didn’t know that PhD students were trained in this way, and that supervisors didn’t just care about your data/article progress, but also how much you have mastered/how to write a review/how to make a presentation and poster/how to enrich your CV/how to apply for funding. To put it more figuratively, the training system in China was probably factory style, whereas now it’s home-based and requires the passing on of skills.

Actually, it’s not just the skills, but also the thinking. I once read a Chinese blog about Liane by a young lecture who graduated from Freie Universität Berlin ten years ago. He described Liane with great admiration, and as there was no overlap in their fields of expertise, I guessed that he might have been impressed by Liane’s personality in just one conversation. The other day, I read a report that said “setting a role model for young female scientists at the start of their careers and female students aspiring to a career in science”. Liane DID just that! Liane and Jeff are what academics are supposed to be in their youth and peak years, and I am fortunate to be able to work with them, which gives me a vague ambition that if I ever become a teacher, I can pass on my knowledge and skills just like them!

New paper in Scientific Reports!

My GFZ collaborator Laura V. Krone just published her first paper from her PhD as part of the EarthShape project. From the drilling campaign in the semi-arid study site in Santa Gracia in Chile, we found multiple weathering fronts at various depths, even reaching as deep as 76 m from the surface. The denudation rate from this site result in a slow turnover time of the entire weathering zone (~7 million years). Despite this, we show that deep weathering is still possible.

(a) Schematic core log. (b) Acoustic televiewer image of the unrolled borehole wall. (c) Core photos of (1) soil and saprolite, (2) saprolite, (3) transition zone between saprolite and saprock; (4–7) saprock, (6) fresh bedrock. Figure from Krone et al. (2021), Scientific Reports, 11, 13057.

Please read the full paper here: https://doi.org/10.1038/s41598-021-90267-7.

EXAFS beamtime at Diamond Light Source

Some “free” time while resting from sample pellet preparation in the glovebox.

Last February 2020, I went to Diamond Light Source in UK together with Liane, Dominique and Thaïs to do Fe and As K-edge EXAFS measurements at the I-20 beamline. We were mainly looking at redox-active Fe-bearing minerals and their interactions with arsenic, phosphate and silica.

Synchrotron beamtime is always an exciting time for me because I get to shoot high energy X-rays to my (synthetic) Fe-bearing minerals. Plus, it allows me to understand the crystal structure of these minerals, and the nature of the nutrients (e.g., Si, P) and contaminants (e.g., As) immobilized on them.

The beamtime was a success, and now it’s time to analyze all those EXAFS data!

I’m now a Doctor (Dr. rer. nat.)!

I successfully defended my doctoral dissertation (Green rust formation and reactivity with arseic species) at the Freie Universität Berlin, Germany last January 17, 2020 with a grade of summa cum laude (mit Auszeichnung).

The first part of my defense was a 30-min presentation of my dissertation, covering a brief introduction and the most significant findings of my projects. It went really smooth and I felt great with the pace of my presentation. After that, it was followed by the “examination” part, which consisted of 30-min of scientific questions and discussion with my doctoral examination committee. It was really nerve-racking, and some of the questions from the members of my committee really caught me by surprise. One of my examiners even asked why Mars was red instead of green! But, I’m glad I was able to answer all the questions from them. This was followed by a private deliberation of the doctoral examination committee. And then, the announcement that I had passed!

It’s part of tradition in German universities that your colleagues give you a doktorhut after passing the doctoral defense. Here’s the hat that my colleagues at the Interface Geochemistry group at GFZ made:

It was really funny that they made a paper doll of me working in a glovebox with the TEM next to it. And of course, the promo shot of the cast of RuPaul’s Drag Race S9 (one of my favorite seasons of the show).

Another tradition, this time from Liane (my PhD supervisor), was to hit the cardboard from the office ceiling with the cork of the champagne bottle. Obviously, I’m not used to opening champagne bottles so I struggled a lot! Haha. And then, I had to sign the “spot” on the ceiling board with your name and signature! It was really cool though.

By the way, I’m the first PhD student from our research group to graduate since Liane moved to GFZ Potsdam. Overall, I’m PhD no. 39 (she was previously at University of Leeds from 1999).

And of course, this PhD journey would not have been possible without the help and support from the following people:

And with that, on to the next adventure as a postdoc!