Stabilization of calcareous sand dunes using phosphoric acid mulching liquid

The water level reduction of Urmia Lake in the northwest of Iran has led to the shrinking of the lake area, exposure of the salt in the dried areas, desertification of shorelines, and creation and development of sand dunes in some coastal areas, especially Jabal Kandi region. The sand particles of these dunes are smaller than 300 mu m and are aragonitic (calcareous). In this research, the potential of stabilizing and fixing of calcareous sand dunes of Jabal Kandi region by spraying diluted industrial phosphoric acid as a novel mulching liquid was considered for the first time. Due to the chemical reaction of calcareous sand with diluted phosphoric acid, in situ dicalcium phosphate dihydrate cement is produced, which sticks the unreacted part of sand particles together and leads to the creation of a stiff calcium carbonate/phosphate crust. The results of the laboratory tests including measuring the penetration resistance and wind erosion modulus of the crust showed that through the use of adequate percentage and volume of phosphoric acid, the produced crust had a considerable mechanical strength and could control the wind erosion of the stabilized sand. This method could be executed with a controlled plan to fix some shifting sand dunes, stop their drifting and change them to windbreakers, especially near rural areas and agricultural lands. Also, in the untreated areas between the fixed sand dunes, re vegetation plans could be executed. (C) 2017 Elsevier Ltd. All rights reserved.