<title>Abstract</title> Understanding the molecular complexity of dissolved organic matter (DOM) is crucial for deciphering ecosystem function and predicting responses to environmental change. Using a continental-scale dataset of molecular formulae generated by Fourier-transform ion cyclotron resonance mass spectrometry through the WHONDRS Project, we reveal fundamental scaling patterns of DOM diversity across watershed characteristics. We show that both local and regional watershed features across latitude reveal…

Critical Zone processes encompass interactions among rock, soil, water, air, and living organisms, essential for quantifying water and nutrient fluxes and predicting downstream river water quality. High-fidelity reactive transport models (RTMs) are important for understanding Critical Zone processes but are typically computationally expensive, which limits their applicability across large catchments. To address these challenges, we developed a scale-adaptive reactive transport simulation framework that balances pr…

Coastal terrestrial-aquatic interfaces (TAIs) are crucial contributors to global biogeochemical cycles and carbon exchange. The soil carbon dioxide (CO₂) efflux in these transition zones is however poorly understood due to the high spatiotemporal dynamics of TAIs, as various sub-ecosystems in this region are compressed and expanded by complex influences of tides, changes in river levels, climate, and land use. We focus on the Chesapeake Bay region to (i) investigate the spatial heterogeneity of the coas…

Abstract Cities are concentrators of complex, multi‐sectoral interactions. As keystones in the interconnected human‐Earth system, cities have an outsized impact on the Earth system. We describe a multi‐lens framework for organizing our understanding of the complexity of urban systems and scientific research on urban systems, which may be useful for natural system scientists exploring the ways their work can be made more actionable. We then describe four critical dimensions along which improvements are needed to ad…

Abstract Mountainous watersheds are characterized by variability in functional traits, including vegetation, topography, geology, and geomorphology, which determine nitrogen (N) retention, and release. Coal Creek and East River are two contrasting catchments within the Upper Colorado River Basin that differ markedly in total nitrate (NO 3 − ) export. The East River has a diverse vegetation cover, and sinuous floodplains, and is underlain by N‐rich marine shale. At 0.21 ± 0.14 kg ha −1 yr −1 , the East River export…