In Situ Measurement of Nitrate Flux and Attenuation Using a Soil Passive Flux Meter.

This work enhances our understanding of catchment-scale N budgets by demonstrating the modification and application of a simple method for direct in situ measurements of vadose zone nitrate leaching and attenuation. We developed a soil passive flux meter (SPFM) to measure solute leaching based on a modified design of ion-exchange resin columns, and we tested the design in numerical simulations, laboratory experiments, plot-scale field experiments, and a catchment-scale field deployment. Our design minimized flow divergence around the resin column to attain nearly 100% capture of surface applied tracers in plot- and catchment-scale deployments.

Urbanization affects stream ecosystem function by altering hydrology, chemistry, and biotic richness.

Catchment urbanization can alter physical, chemical, and biological attributes of stream ecosystems. In particular, changes in land use may affect the dynamics of organic matter decomposition, a measure of ecosystem function. We examined leaf-litter decomposition in 18 tributaries of the St.