Randie studies the cycling of trace metals in diverse marine environments, ranging from coastal areas to the open ocean. She is primarily interested in how bioactive metals such as iron, copper, and cobalt are acquired by marine phytoplankton and bacteria, and how the organic forms of these metals affect their uptake and cycling in the ocean. She uses a variety of analytical techniques to asses the distributions and reactivity of trace metals, including electrochemistry, liquid chromatography, inductively coupled plasma mass spectrometry and electrospray ionization mass spectrometry. She couples both experimental work with at-sea field studies in order to better understand the role of trace metals in global biogeochemical cycles in the ocean.