The Lake Palomas Basin: Dust Engine of the Chihuahuan Desert

The northern Chihuahuan Desert, in the Texas- New Mexico- Chihuahua (Mexico) border region, is one of the most intense regions of dust emission in the Western Hemisphere. A number of playa basins, from Lake Babicora in Mexico to Lake Lucero (White Sands) and the Salt Basin in the USA, are major dust sources within the region. However, the nexus of this global “dust hotspot” is the (Pleistocene pluvial) Lake Palomas basin. Pluvial Lake Palomas extended approximately 200 km across the region: it is now represented by a number of infrequently-inundated, hydrologically-isolated, sub-basins on both sides of the border, regularly emitting dust from their central playas and alluvial margins. Frequent dry-season windstorms push dust plumes from the Lake Palomas basin across the twin cities of El Paso, Texas and Ciudad Juárez, Chihuahua (the Paso del Norte metroplex), arguably the dustiest metropolitan area in North America. Particulate matter (PM10 and PM2.5) concentrations in El Paso and Ciudad Juárez during dust events reach levels unhealthy for vulnerable populations. Asthma rates are elevated in the Paso del Norte, and dust may play an underappreciated role in its epidemiology. To the west, dust from fringes of the Lake Palomas system may cause closures of major transportation corridors and is implicated in fatal road accidents. Dust clouds from the Lake Palomas basin and the surrounding region are annually advected far beyond the Chihuahuan Desert, traveling eastwards across Texas, or to the northeast, where sediments may fall from the sky thousands of kilometers downwind. Dry dustfall events, “dirty rains” and “dirty snows” noticed in Great Lakes region, New England, and Canada almost every spring are manifestations of persistent contemporary aeolian transport of fine sediment from the Southwest, including the Lake Palomas basin, across North America.