نیکو حمزه پور

Cloud properties are highly influenced by mineral dust characteristics and composition and their capacity in nucleating ice. Mineral dusts contributing in cloud formation, are mostly composed of carbonates and soluble salts as they globally originate from arid regions of the world and dried lake beds. Recently due to climate change and lack of water, abandoned agricultural lands which are widely disturbed areas with no surficial crusts nor vegetation cover, have also become an increasing source for atmospheric dust worldwide. Unlike common dust sources, these areas are low in salt and high in organic compounds. The aims of the present study are to investigate the roles of salts, carbonates and organic matter on ice nucleation activity (INA) of mineral dust from a new perspective. Soil and dust samples from four identified dust sources were collected from north to the south of Urmia Playa lake (UPL), northwest of Iran and their major physicochemical properties are measured. Then in a systematic way, carbonates, salts and organic matter of samples are removed by standard soil procedures and their INA is determined by means of a differential scanning calorimeter in two emulsion concentration of 2% and 5%. ΔThet and ΔFhet of all samples increased in salt removed (SR) and carbonate removed (CR) treatments compared to their natural samples except for SR treatment of soil Sa as it was very low in salinity. The mean increases in Thet of SR and CR treatments were 0.97K and 1.2K respectively. The correlation analysis between Thet and Fhet of natural samples with their physicochemical properties revealed that they are positively correlated to organic carbon (OC), total clay and PM10 fraction of the samples while negatively correlated to electrical conductivity (EC), total carbonates (TC) and pH of the samples. thus removal of salts from samples can increase the Thet and Fhet of the SR treatments by increasing water activity or evacuating active IN sites on the surface of miner