Assessment of Soil Chemical Degradation and Salinization in Al-Suda Marsh, Southern Iraq Using Field Measurements and Sentinel-2 Spectral Indices

Abstract

    Al-Suda Marsh in southern Iraq is in danger of becoming uninhabitable because of a lack of water and salinization. This study combines field soil analyses with Sentinel-2 remote sensing to evaluate chemical degradation and salinity. Soil profiles from three horizons (0-60 cm) revealed clay-dominated textures, high electrical conductivity (up to 11.60 dS/m in Cgk2), elevated sulfate (46.5 mmol/L) and sodium, plus heavy metal accumulation (Fe: 1931 mg/kg surface). Spectral indices (NDVI, Moisture Index) derived from October 2022 imagery validated extensive vegetation loss and desiccation, exhibiting a strong correlation with ground data. The results show that salt and metal can move up through low-permeability clays through capillary action, which confirms that remote sensing can be used to monitor marshes. Urgent water restoration is recommended to mitigate toxicity and restore biodiversity. Samples from three horizons (0-60 cm) showed that the textures were mostly clay, the electrical conductivity was high (up to 11.60 dS/m in Cgk2), the CaCO₃ levels were high (33-41%), the organic matter levels were high (19.8-25.3%), and the heavy metals were mostly in the surface layers (Fe: 1911-1931 mg/kg; Cu: 26.9-30.3 mg/kg; Mn: 265-281 mg/kg). Spectral indices (NDVI, Moisture Index) corroborated extensive vegetation loss and desiccation, substantiating ground data spatially. These results show that marsh soils need to be restored quickly to lower salinity and metal toxicity.