Combined effect of salts and Groundwater Fluctuation in Clay Mineral Transformations of some sites in Babil and Al-Diwaniyah Provinces, Iraq

• Sarah H.A. Al-Amidi1,2* , Raid S Jarallah2

  Author

To investigate the mineralogical transformations of clay minerals induced by groundwater table fluctuations and to identify the dominant clay minerals in Babil and Al-Diwaniyah provinces, one representative site was selected in each province. The selected sites were affected by accumulated salts and had been previously modified through land leveling and elevation relative to the surrounding lower adjacent soils and nearby roads. This configuration enabled direct visual observation of groundwater table fluctuations over a period more than 15 years.

The study sites were located at coordinates (N 31°57′3.76″, E 44°48′16.47″) in Babil Province and (N 32°19′2.21″, E 44°22′20.73″) in Al-Diwaniyah Province. Three soil samples were collected from each site: the upper-layer sample represented soils minimally affected by salinity; the intermediate-layer sample represented the zone influenced by fluctuating groundwater movement; and the lower-layer sample represented soils continuously saturated with saline groundwater.

The results obtained from the soils of Babil Province indicated the presence of regular-type chlorite (true chlorite) and revealed mineralogical transformations characterized by the formation of smectite with increasing groundwater salinity influence. In addition, illite and kaolinite minerals were detected. Gypsum was detected exclusively within the groundwater salinity saturation zone and was absent in the other soil layers. Moreover, an increase in palygorskite content was observed with increasing depth, corresponding to conditions of prolonged saturation.

The results obtained from the soils of Al-Diwaniyah Province indicated the presence of swelling chlorite, along with mineralogical transformations involving smectite and montmorillonite. Additionally, palygorskite was identified; however, its intensity and relative abundance decreased with increasing depth, in contrast to the trend observed in the soil samples from Babil Province. This behavior can be attributed to the lower concentration of calcium ions in these soils, as calcium is the key ion controlling gypsum formation rather than sulfate ions. The results also confirmed the presence of illite and kaolinite minerals.

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