Spotlight Series: Qixing Ji

“Spotlight Series” is a group of posts designed to introduce you to the other members of the science team on the research expedition.  Each scientist and his/her research will be featured – I provided the prompts and the scientists added their own information (my comments will be in brackets: [ ]).

Qixing Ji

Qixing Ji

Qixing Ji

Qixing Ji is from Shenzhen, China, a high-tech city of 14 million people and home to one of China’s two stock exchanges.  He recently received his Masters degree and is working on his PhD from Princeton University.

How did you become interested in science? I like solving problems and get a lot of satisfaction from solving a problem.  Science is all about discovering a problem and solving it.  Princeton is a great place to study science and Dr. Ward is an excellent advisor.


Educational background:  My undergraduate degree is in environment engineering from Zhe Jiang University.  I am currently completing my PhD in geosciences at Princeton.


Research interests:  Broadly, my general interest is chemical oceanography – chemical reactions related to biology in the ocean.  Specifically, my interest is in biogeochemistry.  I like chemistry because it’s an amazing subject.  It has a good combination of concepts, observations/experiments, and math.

I mainly study nitrous oxide, N2O, (laughing gas) and its distribution and biological production by bacteria and archaea in the ocean.  Nitrous oxide is an extremely important gas for the climate.  N2O is a greenhouse gas so it traps heat in the atmosphere by absorbing infrared radiation.  It’s actually 300x more powerful than carbon dioxide, meaning for the same mass of each gas, N2O will trap 300x more heat than CO2.

N2O also depletes ozone (which, among other things, protects us from skin cancer) and is currently the most important depletion agent, not CFCs (chlorofluorocarbons).

Human activity has produced more N2O the atmosphere and we need to figure out what processes contribute to this and why.  By studying the amount of naturally-produced N2O by the ocean’s bacteria, we can find the background concentration.  This allows us to then determine how much of the atmospheric N2O comes from humans.

Phytoplankton (magnified).  These are the organisms being studied by Qixing Ji and the other scientists aboard the Endeavor. (photo courtesy of Q. Ji)

Phytoplankton (magnified). These are the organisms being studied by Qixing Ji and the other scientists aboard the Endeavor. (photo courtesy of Q. Ji)

Research aboard the R/V Endeavor: I perform two experiments: the first looks at nitrous oxide concentration and isotopes, and for the second, I do incubation experiments.

For nitrous oxide concentration and isotopes, I look at the natural abundance of both nitrogen isotopes (14Nand 15N) and oxygen isotopes (16O and 18O).  N2O in the ocean exists in an equilibrium with atmospheric N2O.  This is important because biological activities and processes that produce N2O (for example, nitrification) or utilize N2O (ex. denitrification) alter the 15N2O / 14N2O ratio compared to the atmosphere.

In my incubation experiments, I am looking at how organisms produce N2O and the mechanisms by which this occurs.  To do this, I add labeled nitrogen isotopes to ammonium and nitrite [labeled isotopes are 15N], which causes the ammonium and nitrite to become 15NH4+ and 15NO2.  I then introduce these labeled compounds one-at-a-time to my seawater samples and leave them in incubators for 12-24 hours so the organisms can continue to increase their biomass (so 12-24 hours after adding labeled ammonium, I take samples then add the labeled nitrite).  Once that is complete, I will look at the composition of the N2O they have produced – if I added 15NH4+ and there is 15N2O, then ammonium is a source compound.  If the 15N2O came from labeled nitrite (15NO2) then nitrite is a source compound.

Plans for the future: My current goal is to complete my PhD!  Eventually, I think I would like to stay in academia and be a professor.  It’s a very respectful profession and academia is a great environment for scientists.


Back to Ms. B:

Climate change is one of the most serious problems the world is currently facing and has an enormous impact on the environment.  Researchers like Mr. Ji are essential to understanding how humans are impacting climate so we can figure out how to minimize that impact.

Until next time,

Ms. B.


2 thoughts on “Spotlight Series: Qixing Ji

  1. Cristina Medlin says:

    This is fascinating, Mr. Ji seems to have a lot of experience and passion about chemical oceanography. The phytoplankton is larger than I expected plankton to be (?)

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