A UC Davis study on the Salton Sea air basin found that nitrogen oxide emissions from soils (driven by fertilizer use, irrigation, and heat) were underestimated in the official inventory by about a factor of ten. Soil NOx emissions averaged 11 tons per day, ten times the state inventory value.1 Recent work and briefs using the Salton Sea Environmental Time Series data show that nitrogen levels in the Salton Sea water column are extremely high (higher than 95% of U.S. lakes) and that government monitoring systems are missing much of the nutrient-related and hydrogen sulfide–related hazard, but they emphasize incomplete or spatially biased monitoring.2
Nitrates entering the Salton Sea primarily drive hazardous air pollution indirectly through eutrophication and microbial processes, rather than as direct airborne nitrates.3 Nitrates from fertilizers applied in the surrounding Imperial and Coachella Valleys are taken up by arid soils, where microbial processes (nitrification and denitrification) convert them to nitrogen oxides (NOx), a key precursor to ground-level ozone (O3) and fine particulate matter (PM2.5).4
These soil NOx emissions in the Salton Sea Air Basin have been measured at 11 tons per day on average—about 10 times higher than prior state inventories—exacerbating nonattainment of federal air quality standards for ozone and PM.5 Intensive irrigation and fertilizer use amplify these pulses, especially under rising temperatures, linking agricultural nitrate management directly to regional air pollution budgets.6 High nitrate inflows fuel algal blooms, whose decomposition under low-oxygen conditions produces hydrogen sulfide (H2S) gas via sulfate-reducing bacteria.7
H2S routinely exceeds health-based thresholds (e.g., 30 ppb) around the Sea, causing odors, respiratory irritation, headaches, and potential asthma exacerbation in nearby communities like Slab City and Mecca.8 Recent UCLA studies using high-frequency sensors confirmed persistent H2S elevations tied to nitrate-driven nutrient richness, with inadequate monitoring missing peak events.9 NOx from soil and other sources forms secondary nitrate aerosols (part of PM2.5 and PM10), worsening inhalable particulate pollution already heightened by dust from the receding shoreline.10
While playa dust carries salts, metals, and legacy pesticides independently, nutrient overload indirectly worsens air quality by sustaining a chemically reactive lake environment.11 These combined pollutants contribute to chronic respiratory and cardiovascular risks in the low-population but agriculturally intense basin.12