The Anatomy of a Toxic Cloud
The dust that rises from the Aralkum Desert, the name for the exposed seabed of the former Aral Sea, differs from typical desert dust. It is an aerosolized mixture, carrying chemicals from decades of intensive agriculture and industrial activity. Soviet-era irrigation projects, which diverted the Amu Darya and Syr Darya rivers to feed vast cotton fields, caused the sea to shrink dramatically since the 1960s. As the water evaporated, salts, agricultural chemicals, and industrial pollutants became concentrated in the remaining water and finally settled into the sediment.
Today, frequent dust storms—occurring up to 10 times annually—scour this exposed and contaminated surface. These storms transport millions of tons of dust and salt each year, creating plumes that stretch for 400 kilometers. The aerosol composition contains hazardous materials. Analysis shows large quantities of salt, with dust containing up to 90% salt in the winter. Embedded within this saline matrix are residues of numerous pesticides, including organochlorines like DDT (dichlorodiphenyltrichloroethane), HCH (hexachlorocyclohexane), toxaphene, and the organophosphate pesticide phosalone. Many of these, such as DDT and toxaphene, were banned in Western countries due to their carcinogenic effects. The dust also contains heavy metals like lead, mercury, and cadmium from industrial sources and fertilizers that washed into the sea.
A Far-Reaching Fallout
The impact of these toxic dust storms extends far beyond the immediate shoreline, affecting millions of people across Central Asia. Prevailing winds carry the aerosols hundreds of kilometers, depositing them on agricultural land, pastures, and residential areas. This deposition damages crops by increasing soil salinity and coating leaves, which reduces photosynthesis. The zone most severely impacted by these aerosols covers an area of approximately 2 million square kilometers, encompassing western Kazakhstan and most of Uzbekistan and Turkmenistan.
For the human population, the consequences are severe. Inhabitants of the Karakalpakstan region in Uzbekistan, which lies directly in the path of many storms, experience elevated rates of numerous diseases. Respiratory illnesses, throat and esophageal cancer, kidney and liver diseases, and anemia are widespread. High levels of organochlorine pesticides, PCBs, and dioxins have been found in the blood and breast milk of the local population. Infant mortality rates in the region have been among the highest in the world; in the late 1990s, rates were between 60 and 110 deaths per 1,000 live births, far exceeding the national average. The United Nations estimated in 2002 that winds carried 200,000 tons of this toxic salt and sand every day.