Nitrogen and phosphorus in the subtropical Presidio River, northwestern Mexico
The aim of this study was to assess its nitrogen and phosphorus concentrations in the Presidio River, because it receives large volumes of wastewater with high loads of detergents and fertilizers. The mean concentrations of total nitrogen and phosphorus determined between February 2008 and January 2009 were 640 and 167 μg L-1, respectively. The permissible phosphorous concentration established by the Official Mexican Standard NOM-001-SEMARNAT-1996 for pollutants discharge into rivers is 5000 μg L-1. However, according to international standards on phosphorous concentrations in continental water bodies, the Presidio River may be considered hypereutrophic.