Concentration and composition of hydrocarbons in the river Ural mouth zone in the period of high water

Abstract

High concentrations of hydrocarbons were detected in the surface water suspended solids of the near-mouth zone of the river Ural during periods of high water level. On average, 198 and 270 μg/l suspended solids were detected in 2016 and 2017, respectively. Weathered oil alkanes were prevalent in the composition of hydrocarbons. The hydrocarbon content was low in sands with an average of 7.8–14.6 μg/g. Terrigenous high-molecular mostly stable alkanes predominated in their composition. The interannual variability of the content of organic compounds is connected with the river runoff and the supply of oil contaminants is connected with the flood water. The Ural River’s runoff during high-water periods is expected to significantly affect the ecological conditions of the North Caspian Sea.