| الملخص | The study area is covered by Quaternary sedimentsthat weathered from igneous-metamorphic complex which exposed in the north and northeast of Iraq,northwest of Iranand southeast of Turkey.This complex is enrichment by some metallic and heavy minerals. Hence, the streams across this complex may contain economical minerals such as metallic, light, heavy and/or clay minerals that deposits in their banks as placer.
Sediment samples of Tigris and Diyala rivers from Tikrit, Diyala, Baghdad, and Wasit governorates were taken for grain size, mineralogical and chemical analyses,with focus on silt-fine sand fractionsfor economical purpose. In addition, geochemistry data is used to refine our current understanding of trace elements environmental change across the rivers.
Sand fraction is dominated in TigrisRiver’s sediments within the study area, especially, in Baghdad governorate which is reached 99%. Fine fraction is dominated in Wasit governorate where mud is proximately 99%. The change in particle size reflects change in energy of Tigris River in the study area. However, the silt-fine sand sediments appear in Balad Town and disappear in south of Baghdad.
The results show that all major and trace elements in sediments from Tigris River reflect little oscillation in their concentrations across different sites between Tikrit city and Wasit governorate. This slightly change in elements seems to be influence by human activities in the study area. On the other hands, these elements demonstrate different concentrations in sediments from Diyala River in this study. This result indicates that silica oxide is slightly decreased toward downstream in Tigris River, whereas, iron, titanium, aluminum and sulfate oxides, chromium, copper, and manganese are slightly raised toward downstream of the river. Major oxides and trace elements in Diyala River have distribution patterns that match the pattern of the same elements in Tigris River. In addition, MgO, K2O, P2O5, and Zn are increased toward downstream in Diyala River.
However, sediments from Tigris River contain higher concentration SiO2, Al2O3, Fe2O3, Na2O, K2O and Mnthan sediments from Diyala River. Conversely, sediments from Diyala River show double or higher values of CaO, LOI, SO3, P2O5, Cu, Pb, Sr, and Zn. Change in the source of sediments, landuse and anthropogenic input in these rivers may influence on chemistry of their sediments. Thus, using geochemical data in this study show ability to discriminate different rivers even in small area. | |
