Nutrient pollution from agricultural fertilizers contributes to toxic algal blooms and oxygen dead zones in many of the world’s rivers, lakes, and coastal areas, but in intensively fertilized regions such as the Mississippi River Basin (MRB), variation in nutrient loading among years is now driven by climate. Understanding climactic controls on river nutrient export is therefore crucial for predicting and mitigating these environmental problems. In collaboration with the NSF-funded Stream Resiliency research coordination network, I investigated how nutrient loads from the Mississippi River and its major tributaries respond to large-scale climate drivers and agricultural practices. We found that temporal patterns in nutrient loads are highly synchronous at all spatial scales and are linked to large-scale climate variables such as temperature anomalies and ENSO. Indirect effects of warming temperature on nutrient loading emerge at almost continental scales—nitrogen loads from the MRB decrease in warm years independent of changes in river flow.
Smits, A. P., Ruffing, C. M., Royer, T. V., Appling, A. P., Griffiths, N. A., Bellmore, R., et al ( 2019).Detecting Signals of Large‐scale Climate Phenomena in Discharge and Nutrient Loads in the Mississippi‐Atchafalaya River Basin. Geophysical Research Letters, 46. https://doi.org/10.1029/2018GL081166