Mineralogical variations of sand sediments in the Tigris and Euphrates Rivers: implications for agricultural sustainability.

Abstract

Climate change and human activity have impacted the quantitative and qualitative characteristics of sediment content in Iraq's Tigris and Euphrates rivers. This study aims to determine the spatial variation of sediment characteristics, including sand mineral content and degree of maturity, in the two rivers. This study highlights the importance of sediments for agricultural soils and plants, emphasising their role in enhancing soil properties when deposited naturally or added by humans. It evaluates the chemical and physical characteristics of riverbed sediments, with a particular focus on identifying the mineral composition of both heavy and light sand minerals. Furthermore, it examines their mineral maturity. Chemical tests revealed an increase in the electrical conductivity downstream in both rivers. Physical assessments indicate a downstream decrease in the proportion of sand particles and a corresponding increase in the proportion of clay particles. Light sand minerals constitute a significant portion, ranging from 95.6 to 96.8% of the total mineral content, encompassing diverse minerals such as quartz, feldspar, and fragmented rock minerals. Heavy sand minerals account for between 3.2 and 4.4% and include opaques, chlorite, pyroxenes, hornblende, mica, zircon, tourmaline, and garnet. This trend shows a decrease in the overall maturity of these sediments, with a maturity trend shifting towards physical maturity. In contrast, the maturity index of light sand minerals decreases with increasing distance travelled along the two rivers. Understanding these mineralogical variations provides insights into the intricate interplay of geological, climatic, and anthropogenic factors shaping river-loaded sediments. This knowledge helps in choosing sustainable agricultural practices for soils to which these sediments are added.