Data-driven Nutrient-landscape Relationships across Regions and Scales.

Area of Science:

• Environmental Science
• Hydrology
• Ecology

Background:

• Previous research linked nutrient exports to upstream factors but often overlooked hydrological influences.
• Understanding nutrient dynamics is crucial for managing water quality in large river basins.

Purpose of the Study:

• To investigate the relationship between nutrient concentrations (total nitrogen and total phosphorus) and upstream landscape characteristics (population density and arable land cover).
• To analyze these relationships across diverse scales and hydroclimatic conditions in the Baltic Sea and Mississippi River basins.

Main Methods:

• Compiled existing data from previous studies focusing on the Baltic Sea and Mississippi River basins.
• Analyzed correlations between nutrient concentrations and land cover (arable land) and human activity (population density).
• Compared relationships across various subcatchment scales and hydroclimatic settings.

Main Results:

• Relationships between nutrient concentrations and upstream factors were generally stronger in the Baltic Sea basin than in the Mississippi River basin.
• Total nitrogen (TN) concentration showed a strong and consistent correlation with arable land cover across all scales and regions.
• Total phosphorus (TP) concentrations appeared more influenced by faster surface transport mechanisms.

Conclusions:

• Nutrient export, particularly TN, is significantly influenced by land cover, with arable land being a key factor.
• TN export is likely dominated by slow release from legacy stores in the subsurface, while TP export is more related to surface processes.
• The findings highlight the importance of considering landscape characteristics and hydrological pathways in nutrient management strategies.