This modeling study mapped atmospheric inputs of sulfur and selenium to agricultural soils for 2005 to 2009 and projected them to 2095 to 2099 under two socioeconomic scenarios. Cleaner energy and air pollution controls reduce emissions, so atmospheric inputs of both elements to Northern Hemisphere farmland are projected to fall sharply. The authors argue that fertilizer strategies may be needed to offset the loss, and that stream records in the USA already show declining selenium fluxes in some watersheds.
Key numbers
- Projected decline in atmospheric selenium inputs to Northern Hemisphere agricultural soils: 55 to 80% by the end of the century (Abstract).
- Asia, North America and Europe agricultural soils: 70 to 80% decline under SSP1-2.6 and 55 to 65% under SSP5-8.5; Africa, Australia and South America: 3 to 25% (Results, p. 3).
- Global atmospheric selenium inputs: 31% lower under SSP1-2.6 and 23% lower under SSP5-8.5 (Results, p. 2).
- These are modeled projections, not measurements.
Methods (brief)
The SOCOL-AER aerosol-chemistry-climate model with an atmospheric selenium chemistry module simulated the inputs to land. Anthropogenic selenium emissions were scaled from sulfur dioxide emissions. Modeled trends were compared with particulate selenium observations and with USA stream concentration records.
Evidence fitness
Supports context on why soil selenium inputs, and therefore crop selenium, may change over time. It does not measure selenium in food or people and does not support intake or toxicity statements.
Limitations
Model-based; only two future scenarios; the effect on crops depends on soil chemistry, speciation and management, which the model does not resolve; biogenic emission responses to climate are uncertain.
Related evidence
Update history
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