Water quality index and physicochemical parameters effect on the corrosion rate of steel along the Egyptian Mediterranean Sea

Abstract

This study aims to discuss some physicochemical parameters and their effect on steel corrosion rate in natural seawater collected from different sectors along the Egyptian coast of the Mediterranean Sea. Samples were collected from eight eastern sectors including 48 stations during autumn of 2021, and from twelve western sectors including 72 stations during spring of 2022. The steel corrosion rate was determined by using the weight loss technique on a laboratory scale. Results ranges and total averages revealed that salinity (20.630–42.020) 38.540‰ in 2021 and (37.771–39.304) 38.831‰ in 2022; the pH (8.28–8.41) in 2021 and (7.69–8.15) in 2022; dissolved oxygen (3.00–4.73) 3.65 mg/L in 2021 and (2.88–6.98) 4.481 mg/L in 2022; oxidizable organic matter (1.10–2.60) 2.08 mg/L in 2021 and (depletion–0.93) 0.304 mg/L in 2022; phosphate (0.022–10.876) 4.142 µM in 2021 and (depletion–5.432) 0.612 µM in 2022; nitrite (depletion–1.325) 0.379 µM in 2021 and (depletion–2.50) 0.211 µM in 2022; sulphate (2.044–3.876) 2.997 g/L in 2021 and (1.544–4.425) 2.645 g/L in 2022; and the steel corrosion rate (0.020–0.158) 0.088 mm/y in 2021 and (0.006–0.197) 0.078 mm/y in 2022. According to the Principal Component Analysis (PCA) data, the western stations had good water quality, while the eastern stations were polluted in different degrees related to the increase in human activities. Two statistical equations were obtained from the correlation between the steel corrosion rate and their corresponding physicochemical parameters.