Final answer:
Daniel's field of study is closely related to Earth Science, while Sanya's field of study is closely related to Environmental Science.
Step-by-step explanation:
Daniel's field of study is closely related to Earth Science as he is researching the effects of tropical storms on coastal erosion. Sanya's field of study is closely related to Environmental Science as she is investigating the impact of industrial plant discharge on the pH concentration of freshwater swamps. Both of their studies involve understanding how natural and human-induced factors can affect the environment.