Abstract
Recent research has found that iron (Fe) concentrations in freshwaters have increased strongly during the last decades. Given the multifaceted role that Fe plays in aquatic ecosystems, the reported trend is likely one with multiple and far reaching consequences. Several studies show that it plays a significant role in the ongoing browning of freshwaters. Notably, little attention has been given to the underlying cause/s of the striking Fe trends. The proposed research aims to advance our understanding regarding which mechanisms control the prevalence of Fe in aquatic systems. More specifically, we will investigate A) the role that hydrology (influenced by climate change and land-use) may play by modifying redox dynamics and thereby Fe mobility, and B) what role atmospheric sulfate deposition may play by altering the availability of reactive sulfur, which may interact with Fe and change its mobility. Three complementary approaches will be used: 1) Time-series analyses of global long-term patterns in Fe concentrations, 2) sediment sampling to establish Fe accumulation rates in lakes and its relation to changes in hydrology and sulfate deposition, and 3) microcosm experiments to establish mechanistic links between redox dynamics, sulfate availability and the mobilization of Fe. This project brings together scientists and stakeholders to enhance our understanding of what controls Fe mobility and how to manage brownification.
Sweden