Nitrogen Isotopes Reveal High NOx Emissions from Arid Agricultural Soils in the Salton Sea Air Basin

Details

• Personal Author:
  Faloona IC ; Lieb HC ; Maldonado M ; Olmedo L ; Ruiz E ; Torres C ; Walters WW ; Faloona IC ; Lieb HC ; Maldonado M ; Olmedo L ; Ruiz E ; Torres C ; Walters WW
• Description:
  Air quality management commonly aims to mitigate nitrogen oxide (NOx) emissions from combustion, reducing ozone (O3) and particulate matter (PM) pollution. Despite such ongoing efforts, regulations have recently proven ineffective in rural areas like the Salton Sea Air Basin of Southern California, which routinely violates O3 and PM air quality standards. With over $2 billion in annual agricultural sales and low population density, air quality in the region is likely influenced by the year-round farming activity. We conducted a source apportionment of NOx (an important precursor to both O3 and PM) using nitrogen stable isotopes of ambient NO2, which revealed a significant contribution from soil-emitted NOx to the regional budget. The soil source strength was estimated based on the mean δ15N-NOx from each emission category in the California Air Resources Board's NOx inventory. Our annual average soil emission estimate for the air basin was 11.4 +/- 4 tons/d, representing approximately 30% of the extant NOx inventory, 10× larger than the state's inventory for soil emissions. Unconstrained environmental factors such as nutrient availability, soil moisture, and temperature have a first-order impact on soil NOx production in this agriculturally intensive region, with fertilization and irrigation practices likely driving most of the emissions variability. Without spatially and temporally accurate data on fertilizer application rates and irrigation schedules, it is difficult to determine the direct impacts that these variations have on our observations. Nevertheless, comparative analysis with previous studies indicates that soil NOx emissions in the Imperial Valley are likely underrepresented in current inventories, highlighting the need for more detailed and localized observational data to constrain the sizeable and variable emissions from these arid, agricultural soils. [Description provided by NIOSH]
• Subjects:
  Agriculture Air Pollution Occupational Health Particulate Matter Safety
• Keywords:
  Air Pollution Sampling Air Quality Monitoring Environmental Health Monitoring Nitrogen Oxides Particulates Soil Analysis
• ISSN:
  2045-2322
• Document Type:
  Text
• Funding:
  Cooperative Agreement
• Genre:
  Journal Article ; Journal Article
• Place as Subject:
  Atlanta Region [OSHA] ; California ; San Francisco Region [OSHA] ; South Carolina
• CIO:
  National Institute for Occupational Safety and Health (NIOSH) ; National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health ; Workplace Safety & Health
• Location:
  North America ; North America
• Volume:
  14
• NIOSHTIC Number:
  nn:20070325
• Citation:
  Sci Rep 2024 Nov; 14:28725
• Contact Point Address:
  Ian C. Faloona, Department of Land, Air, and Water Resources/Air Quality Research Center, University of California, Davis, California, USA
• Email:
  icfaloona@ucdavis.edu
• CAS Registry Number:
  Nitrogen dioxide (CAS RN 10102-44-0) ; Nitrogen dioxide (CAS RN 10102-44-0)
• Federal Fiscal Year:
  2025
• Performing Organization:
  University of California - Davis
• Peer Reviewed:
  True
• Start Date:
  20010930
• Source Full Name:
  Scientific Reports
• End Date:
  20270929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f0f4275d95cf13c773f8466b7a7165a309cbe10b75fa5a62cff75a9f9dfa384882674272cf09928e7ad15a489ac8b37c1be6a9e1298847a032a15368d8bac11d
• Download URL:
  https://stacks.cdc.gov/view/cdc/208559/cdc_208559_DS1.pdf
• File Type:
  [PDF - 2.57 MB ]