Photo: Erik Jepsen/UC San Diego

A Scientist's Life: Lihini Aluwihare

Lihini Aluwihare studies the chemistry of organic matter in the oceans

Lihini Aluwihare, a chemical oceanographer, was born in Sri Lanka and lived in Zambia and England before moving to the United States for college and post-graduate studies. Arriving at Scripps Institution of Oceanography at UC San Diego in 2000, she studies the chemistry of organic matter in the oceans and serves as co-director of the Scripps Center for Oceans and Human Health, which was launched in 2013.

explorations now: Describe what you do for a living.

Lihini Aluwihare: In my field I’m called an organic geochemist. In a very basic sense, I’m using molecules to tell a story about the processes on Earth that involve organisms. If you think about the number of different molecules that are on Earth most of them are organic, meaning they were made by organisms. My interest lies in trying to understand those molecules and what their structure tells us about the processes that have acted on them.

en: How did you select this as a career?

LA: I was interested in organic chemistry even in high school, where I had two fantastic teachers. Teachers make a huge difference. They were very fun and we did a lot of experiments and that was really great. At that point I pretty much decided that I would eventually get a PhD in chemistry. But once I got my bachelor’s in chemistry at Mount Holyoke College, I had the opportunity to do a summer internship at Woods Hole [Oceanographic Institution or WHOI]. During that time I heard about the opportunities for doing field work and some of the “forensic” aspects of marine chemistry in which you are really trying to learn something about the environment by studying different molecules. I found that much more interesting than potentially sitting in a lab in a basement. So I switched, applied through a fast track for graduate school, and was accepted at WHOI that summer.

en: What attracted you to this field in the first place?

LA: I think, for me, biology was a lot of memorizing, and physics was more math oriented. I was very good at algebra and trigonometry but I was not good at calculus, and there’s a lot of calculus in physics. But chemistry had the jigsaw puzzle aspect of it. Molecules are built on particular rules so I really enjoyed that. I also realized that if you really get into chemistry it’s really not about memorizing. You can actually predict reactions and things like that if you understand the fundamental rules.

en: Why did you choose to come to Scripps?

LA: I first came to Scripps because I was interested in working with (Scripps Professor) Farooq Azam as a postdoctoral scholar, after my PhD I had done a lot of chemistry, but I realized with my field that microorganisms are really important for shaping the chemistry that I study in the ocean. So I was interested in learning a little bit more about microbial ecology from Farooq. But then a job opening came up at Scripps and it was a dream opportunity. In terms of what my advisor and my instructors at WHOI would have wished, they couldn’t have come up with a better plan. So it was natural for me to apply and I think I was very lucky with respect to the opportunities that were available at that time.

en: What have you liked best about your time at Scripps?

LA: It’s been a great journey. I have built some good relationships with my colleagues but also I think it’s been about the quality of graduate students that I’ve been able to advise, and the relationships that I’ve built with them over the years, and the various people that I’ve touched through my work here at Scripps and UC San Diego.

en: What are some of the major questions in your field?

LA: In terms of the big picture, the questions pertain to the carbon and nutrient cycles. We talk a lot about how the elements on Earth are recycled. For example, they go through organisms, they are dissolved in the ocean, can be incorporated into the crust, and are released back into the atmosphere and ocean. There is this entire cycling of chemical elements that takes place on Earth, and biology is sort of a stop along the way for some important elements like carbon, nitrogen, and phosphorous. So the important questions revolve around how organisms use these elements but also what they do with them.

I’m particularly interested in organic molecules that seem to resist degradation on short time scales. What is it about their composition? What is it about their function, potentially, in organisms, that might result in the production of these compounds that stay in the ocean for thousands of years and lock-up some atmospheric carbon dioxide.

en: What are some of the tools and methods used in your research?

LA:  I use a lot of traditional chemistry tools. It’s a lot like (the TV show) CSI! Basically the instruments that you see in those labs on TV are a lot of the same that we use as well, but for different purposes. I have a lab with different instruments that are used for gas chromatography and liquid chromatography and mass spectrometry. These are essential tools that allow us to simplify the very complex mixture of molecules we find in the environment, whether it’s in dolphin blubber, sediments, or in the water column.

Fundamentally, the idea is that these molecules, because of their composition and their isotopic signature, have something unique about them so we can either use them as tracers for different processes or we can look at those molecules and try to understand what generated them and learn where they came from and where they are going.

en: What is the Scripps Center for Oceans and Human Health?

LA: The center is looking into potentially toxic chemicals in the environment. The molecules that I’m interested in are present in marine organisms and have a very unique chemical structure. They include markers for natural microbial processes that take place in the ocean and also markers of anthropogenic activities. We’re examining whether these molecular markers can be used to trace the relationship of humans to their seafood and things like that.

en: Who are you collaborating with in the center?

LA: My group and my collaborator at San Diego State University, Eunha Hoh, are focusing on the compounds you can think of as contaminants in dolphin blubber. Of course we don’t eat dolphins, but they are a good sentinel species because they integrate the food web dynamics in the region. They sit at the highest trophic level so the buck stops with the dolphins. They integrate everything that has happened in the food web up to that point.

My graduate student Nelly Shaul, in collaboration with Eunha Hoh and me, has identified 300-plus compounds in blubber that contain either chlorine or bromine, and this includes anthropogenic contaminants, from PCBs to DDT-related compounds and natural compounds.

If dolphins contain these compounds, it’s likely tuna will contain these compounds, as well as swordfish, for example, because they all feed at the same trophic level and those are organisms that we do eat.

This project includes a collaboration with the UC San Diego Department of Pediatrics in which we are able to study breast milk samples that have been donated to the newborn nursery. One of the goals there is to ask questions about the suite of “contaminant” compounds that are present in humans.  These compounds could impact fetal development, or be of concern once the baby starts to drink breast milk. This is all very speculative because we really don’t know what the impacts are. But I think that the doctors are certainly interested so I think we’ll learn a lot from that collaboration in general.

en: Do you have any advice for those looking into a career in oceanography, especially young women?

LA: The idea of creativity is important because I think that science is really a creative endeavor and in oceanography it’s creativity in a variety of different ways. I mean, we go to sea and we have to be plumbers and electricians as well as scientists. We have to splice wires, and at the same time we have to deal with very sensitive instrumentation. There are a lot of new experiences on a day-to-day basis. Our jobs are really not very constrained. I think a lot of people have this idea that we work in this ivory tower—a unique isolated environment. Our jobs are much more varied than you might imagine.

I think that kids should appreciate that there are many different ways to contribute and be creative, and science is one of them. I think in general the message is that there is nothing particularly male about the pursuit of science. I think little girls are just as excited about the natural world as little boys. There is really no particular reason that girls should not be just as excited.

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