Limited progress in nutrient pollution in the U.S. caused by spatially persistent nutrient sources

• DOI: 10.1371/journal.pone.0258952
• Publication Date: 2021-11-29T18:28:39Z
• Authors: Rebecca J. Frei; Gabriella M. Lawson; Adam J. Norris; Gabriel Cano; Maria Camila Vargas; Elizabeth Kujanpää; Austin Hopkins; Brian Brown; Robert Sabo; Janice Brahney; Benjamin W. Abbott
• Keywords: Nutrient pollution

Human agriculture, wastewater, and use of fossil fuels have saturated ecosystems with nitrogen phosphorus, threatening biodiversity human water security at a global scale. Despite efforts to reduce nutrient pollution, carbon concentrations increased or remained high in many regions. Here, we applied new ecohydrological framework ~12,000 samples collected by the U.S. Environmental Protection Agency from streams lakes across contiguous identify spatial temporal patterns leverage (an indicator flux). For within ecoregions, quantified trends for sites sampled repeatedly 2000 2019, persistence over that period, patch size sources sinks. While observed various were persistent potentially because historical legacies, consistent sources, inherent differences removal capacity ecosystems. Watersheds showed strong critical source area dynamics 2–8% land accounted 75% estimated flux. Variability contribution was greatest catchments smaller than 250 km 2 most parameters. An ensemble four machine learning models confirmed previously relationships between combination cover, demonstrating how activity interactively determine balance. These findings suggest targeted interventions small portion landscape could substantially improve quality continental scales. We recommend dual approach first prioritizing reduction inputs exert disproportionate influence on downstream chemistry, second, enhancing restoring hydrological connectivity both laterally vertically stream networks.