Spatial and Temporal Variation of Physicochemical Parameters and Trace Metals in Shatt al-Arab Estuary and Adjacent Coastal Areas Southern Iraq

Purpose: The physical and chemical factors have a significant role in defining the aquatic environmental features in estuarine and coastal environments, particularly in the light of climate change effects in addition to human activity. The proposed study will evaluate the environment and the levels of certain trace elements in water within the Shatt al-Arab estuary and Iraqi coastal waters in southern Iraq. Methodology: Four water locations were sampled along the stretch from the Naqaa area to the breakwater at the Grand Faw Port in two seasons: summer (September 2025) and winter (January 2026). Various chemical and physical parameters were examined, including water temperature, pH, turbidity, electrical conductivity (EC), total suspended solids (TSS), biochemical oxygen demand (BOD5), and dissolved oxygen (DO). Also, trace element concentrations (Pb, Cu, Mn, Zn, Fe, Cd, Ni) were identified. Findings: The findings indicated an evident spatial and temporal difference in water quality features. During the summer, the highest electrical conductivity values (58.8-58.9 mS/cm) were observed at stations 3 and 1, respectively. The value of dissolved oxygen was highest in winter (10.4 mg/L) and lowest at station 2 (estuary area) in summer (6.6 mg/L). Turbidity of water was maximum (396.6 NTU) in the winter at station 2. The trace elements also showed significant seasonal variations, except at stations 1 and 2, where the highest iron concentration (6.688 mg/L) was found in the estuary region during winter and the lowest (1.093 mg/L) during summer. In the meantime, the maximum lead level (4.385 mg/L) was first observed at station 1 in the summer and evidently decreased during the winter. Unique Contribution to Theory, Practice and Policy: This paper gives a detailed evaluation of the spatial and temporal changes in the physical and chemical characteristics along with the distribution of trace elements and the effect on the environmental factors on water quality in estuarine and coastal water systems, which help in supporting environmental monitoring programs and decision-making processes in resource management and reducing the water contamination in southern Iraq.