Quantifying Sampling Biases and Silicate-Derived Sr in Continental Runoff: A Coupled 87Sr/86Sr - 88Sr/86Sr Study
The Strontium isotope (87Sr/86Sr) record of seawater is one of the best-reconstructed marine isotope records. It has been widely used to estimate temporal changes of continental and hydrothermal inputs to seawater, and temporal variations have been correlated with periods of glaciations, mountain building and major magmatic events. Despite this impressive record, estimates of the present-day mass balance of strontium in seawater fundamentally disagree, highlighting the challenges of interpreting the marine strontium isotope record. This project aims at investigating how severely present estimates of continental runoff into the ocean are biased, and how such biases can be corrected. The interpretation of the marine record critically hinges on an unbiased understanding of the present-day mass balance and forcing factors. In addition to the radiogenic (87Sr/86Sr) isotope composition, the stable (88Sr/86Sr) isotope signature may yield insights into the balance of silicate- vs carbonate-derived strontium, and thus the balance between silicate and carbonate weathering. The study will be conducted under the umbrella of the Global Rivers Observatory, a collaborative, international network of scientists and community volunteers aimed at observing river systems in time-series fashion. Citizen scientists and REU students will be engaged in sampling representative rivers draining the West and East coasts of North America. Local schools are invited to participate in the "My River, My Home" student art project.