Rainfall-induced fecal indicator organisms transport from manured fields: model sensitivity analysis.

Microbial quality of surface waters attracts attention due to food- and waterborne disease outbreaks. Fecal indicator organisms (FIOs) are commonly used for the microbial pollution level evaluation. Models predicting the fate and transport of FIOs are required to design and evaluate best management practices that reduce the microbial pollution in ecosystems and water sources and thus help to predict the risk of food and waterborne diseases.

Characterizing the isotopic composition of atmospheric ammonia emission sources using passive samplers and a combined oxidation-bacterial denitrifier approach.

Rationale: Ammonia (NH3) emissions are a substantial source of nitrogen pollution to sensitive terrestrial, aquatic, and marine ecosystems and dependable quantification of NH3 sources is of growing importance due to recently observed increases in ammonium (NH4(+)) deposition rates. While determination of the nitrogen isotopic composition of NH3 (δ(15)N-NH3) can aid in the quantification of NH3 emission sources, existing methods have precluded a comprehensive assessment of δ(15)N-NH3 values from major emission sources.

Methods: We report an approach for the δ(15)N-NH4(+) analysis of low concentration NH4(+) samples that couples the bromate oxidation of NH4(+) to NO2(-) and the microbial denitrifier method for δ(15)N-NO2(-) analysis.