In the morning of April 28, 2021, Mr. Zhikun Chen successfully passed his PhD oral comprehensive exam. The title of his exam report is “Sources, behaviors, and transformations of organophosphate esters in the coastal environment”. His profound knowledge and excellent presentation helped him win a good evaluation from the external examiner, Dr. Xianming Zhang, and other examining committee members (Drs. Fuzhan Nasiri, Zhi Chen, Maria Elektorowicz, and Chunjiang An).