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While there are many risks associated with the drying of the Salton Sea, perhaps the most concerning is the risk to public health. Previous posts on this blog discussed the health effects of dust from the Salton Sea, and that these health effects could end up costing around $29 billion. However, you may be thinking that these risks and costs are exaggerations or scare tactics. How could the dust from the Salton Sea make such a big difference when it is relatively small (343 square miles) when compared to the whole Salton Basin area of 8,360 square miles? Also, the majority of the basin is not covered by crops to reduce the wind erosion and transport of dust. So how can the drying of the Salton Sea which is approximately 3% of the total basin area, have such a disproportionate impact on the air quality? The answers to these questions lie in the composition of the sediment that lies below the Salton Sea.

However, we should first talk about the two measurements of airborne dust that are regulated by the U.S. Environmental Protection Agency (EPA): PM10 and PM2.5. The PM in these measurements stands for particulate matter and the numbers following them are the maximum diameter of the dust particles. For instance, PM10 is the mass of particles in the air with a diameter less than 10 micrometers. These diameters were chosen because particles less than 10 micrometers are small enough to travel into your lungs, and particles smaller than 2.5 micrometers can enter the bloodstream and cause the majority of the “haze” that leads to reduced visibility.[1] Therefore these two measurements are a good indicator of the potential health risks associated with dust, and in fact, Imperial County is already exceeding the EPA limits for these particulates.[2]

pm2_5_graphic_lg

Particle diameter sizes.
Obtained from U.S. EPA

So how will the drying of the Salton Sea cause PM10 and PM2.5 to increase so drastically that the health effects can add up to $29 billion?  The reason is the presence of salt, and more specifically, the type of salt in the sediment that will be exposed. A recent study by Buck et al. (2011) found that the type of salt forming a crust on recently exposed areas of the Salton Sea shore and its structural properties had a significant impact on the amount of PM10 emissions.[3] When minerals and environmental conditions are present that cause large salt crystals to grow, this generally forms a crust that will stabilize the soil and keep dust from being blown away. iMPerial-valley-dust-storm
A 2013 dust storm that impacted the Imperial Valley. Obtained from The Desert Review

However, at the Salton Sea, only small salt crystals are formed and these prevent soil aggregation, which destabilizes the soil and causes “…a continuous source of fine materials for dust emissions”.[4] This is one of the reasons why.the small area of the Salton Sea can have such a disproportionate impact on air quality and highlights the importance of maintaining water in the sea to prevent dust emissions. Luckily, the majority of the restoration plans keep this in mind, and several projects have been shown to successfully maintain habitat and perform dust abatement. However, action needs to be taken to implement these types of restoration before it is too late.

Written by Jaben Richards


[1] http://www3.epa.gov/airquality/particlepollution/basic.html

[2] http://www3.epa.gov/region09/air/imperial/index.html

[3] Buck B.J, J. King, and V. Etyemezian. 2011. Effects of Salt Mineralogy on Dust Emissions, Salton Sea, California. Soil Sci. Soc. Am. J. 75:1971–1985. https://dl.sciencesocieties.org/publications/sssaj/abstracts/75/5/1971

[4] Buck et al. (2011) As Above.