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CCB Graduate Student, Da Chen, Ph.D.
Polybrominated Flame Retardants in Birds of Prey from U.S. and China
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Da Chen, in his research lab at Virginia Institute of Marine Science (VIMS) |
Da Chen began his Ph.D. graduate work at the Virginia Institute of Marine Science (VIMS) in 2003, after earning a B.S. and M.S. in Environmental Science from Nanjing University, China. He studied brominated flame retardants and other persistent organic pollutants in birds of prey and their eggs. Chen found it natural to collaborate with Dr. Bryan Watts, who has worked on peregrine falcon recovery for years and annually collects addled eggs. The addled eggs were perfect target matrices for Chen’s organic pollutant study. Dr. Watts also served as one of Chen’s Ph.D. review committee members.
Chen’s dissertation research focused on the examination of persistent organic pollutants in birds of prey such as peregrine falcons and bald eagles. Birds of prey feed high in the food web. They can accumulate contaminants through bioaccumulation and biomagnification, making them particularly sensitive to environmental contamination. Therefore, birds of prey are ideal target subjects for examining the contamination of emerging contaminants in the environment. On the other hand, because birds of prey are sensitive to environmental contamination, their reproduction or behavior may be harmed by some toxic chemicals. Examination of contaminants in their bodies or eggs may be beneficial in evaluating the chemical stresses they encounter.
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Addled peregrine falcon eggs |
Before starting his research, Chen found a few studies describing birds of prey and their potential for elevated exposure to brominated flame retardants, a group of chemicals widely present in many consumer products. However, relevant studies were scarce. Polybrominated diphenyl ether (PBDE) flame retardants are widely found in textiles, polyurethane foams, plastics, furnishings and electronics, and can contaminate air, water, soil and sediments and make their way into the food chain. To better understand the contamination patterns of these chemicals in the environment, Chen chose birds of prey as target speciesfor his research. In the preliminary research stages, Chen examined aquatic (i.e., osprey) and terrestrial-feeding species (i.e., peregrine falcon) and observed significant contamination patterns between them. The terrestrial birds contained more of the chemicals on which the research was mainly focused. Therefore, more time was spent examining terrestrial raptors.
In addition, to understand the contamination scenarios on an international scale, birds from both the U.S. and China were examined, which lead to very interesting findings. Contaminant loads in birds from different areas reflect the usage history and regulations. The major PBDE flame retardant manufacturers in North America did not stop producing Penta and Octa-BDE commercial formulations until 2004. Both U.S. and China lack national regulations on the production and usage of PBDEs. As a consequence, the birds from the U.S. and China exhibited higher loads than birds from Europe where voluntary actions by industries have been taken for years. Also, U.S. birds exhibited substantial contamination of PCBs, whereas Chinese birds contained far less PCBs, but more DDTs. That is because China used more DDTs, but less PCBs than the U.S.
As a non-native English speaker, writing was the biggest challenge Chen says he encountered in the first several years of his thesis work. His advice to prospective graduate students in biology is to practice scientific writing, which is very essential in graduate studies, because it provides a researcher an opportunity to organize what has been learned, integrate findings and critically think through his research.
Chen credits Dr. Watts and his colleagues for providing him detailed background information such as nest distribution, diet composition and biological behavior relating to the species of addled eggs, which made it possible to correlate contamination patterns with different factors and provided more insights into the contamination scenarios. Chen says Watts’ addition of invaluable research matrices (addled eggs) and many suggestions and comments for his dissertation work greatly improved his research quality. In August 2009, Chen defended his dissertation, Polybrominated Diphenyl Ether Flame Retardants in Birds of Prey from U.S. and China, to earn his Ph. D. in Biology from VIMS.
If he had additional time and resources to do further research relating to his dissertation work, Chen said he would continue emerging contaminants studies using birds of prey as target species. He would examine other contaminants, such as pharmaceuticals and personnel care products, which may also cause toxic effects on birds. Chen plans to continue his research in a post-doctoral position for several years, with the goal of eventually becoming a professor at a research university.
Da Chen's Ph.D. Dissertation is available online via the Virginia Institute of Marine Science library. Click on the citation below to open it.
Related link:
List of all CCB Graduate Students' Theses >>
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