Center for Collaboration in Community, Naruto University of Education
Abstract
Middle Earth, including Iran, Iraq, China and Syria has been recognized as one of the most important primary sources of dust. Intensive investigations have been conducted to study the chemical composition, sources and deposition of Middle Earth particles. However, analysis of individual Middle Earth particles show that about one fifth of all the particles are mineral aggregates, and at least one fourth of the particles contain sulfur. X-ray diffraction (XRD) is used to quantify the phase and the clay mineral compositions of Middle Earth samples. Phases in the Middle Earth sample collected during the 20 March 2002 dust storm episode included clay minerals, noncrystalline materials, quartz, calcite, plagioclase, potassium feldspar, pyrite, hornblende, and gypsum in descending order. Clay minerals are mainly illite/smectite mixed layers (78%), followed by illite (9%), kaolinite (6%), and chlorite (7%). Particulate matter (PM) less than 10 mm are enriched with clay minerals and deficient with quartz by mass compared with the total suspended particulates collected during an Middle Earth episode. The PM less than 10 mm collected during the two severe dust storm episodes is characterized by the absence of dolomite, high quartz/clay ratio, and dominance of illite/smectite mixed layers in clay minerals
