Ironing out the biogeochemistry of metals in oceanic ecosystems
Metals play a critical role in ecosystems as essential micronutrients, toxic contaminants, and tracers of biological and physical processes. The fate of metals in the environment is largely governed by organic metallophores – ligands that bind to metals and affect their solubility and reactivity, and bioavailability. Thus explaining metal distributions in the environment and assessing their impact on global productivity and carbon/nutrient cycles requires fundamental knowledge of the source and chemistry of organic ligands. Iron is a key limiting nutrient in over a third of the surface ocean due to its scarce solubility in seawater. Nearly all dissolved iron is bound to organic ligands that keep it in solution and also affect which organisms can take it up. Yet characterizing organic ligands has remained a formidable analytical challenge due to the complexity of organic matter in the ocean and the trace quantities of ligands and metals. Our research focuses on the development of sensitive mass spectrometry based analytical methods for identifying and quantifying the specific organic ligands present in complex environmental samples. These new tools have enabled us to survey the composition of organic ligands across the ocean and determine their sources, reactivity, and bioavailability. In this talk, I’ll discuss how this molecular-level insight into the chemistry of organic ligands in the environment sheds light on the mechanistic linkages between metals and marine ecosystems.
