TIME-SERIES INSIGHTS TO TRACE METAL DYNAMICS IN ALASKAN CATCHMENTS

Trace metals are critical to ecosystem health and productivity in marine and freshwater environments, but the processes controlling the temporal and spatial distribution and fate of metals in glacial watersheds remain poorly understood. Here we present extensive time-series trace metal data from a suite of Alaskan river systems of varying glacial coverage. Our intention is to describe the source and cycling of metals in glacial watersheds, and how this evolves over the hydrologic year. We examine the detailed size partitioning of riverine metal loads over time. We find that metal partitioning is clearly influenced by glacier coverage and the seasonal evolution of metal sources and cycles within a watershed. The studied systems have trace metal loads that are affected by both glacial and terrestrial processes, with their relative importance in regulating metal loads varying seasonally, by particular metal and size fraction, and by the percent of the catchment that is glaciated. These results shed important light on the behavior of metals in these systems and their evolution under continued ice loss.