Integrated approaches to assess water quality in two spots along the western Mediterranean Sea, Egypt

This study aimed to assess the status of seawater quality in the Western Mediterranean Sea, Egypt. The measurement of seawater quality was carried out at two regions, namely El Dekhila harbour and Abu Talat regions (2018–2019). The investigated parameters included pH, salinity, DO, BOD, COD, nutrient salts, metals (Fe, Mn, Zn, Cu, Pb, Cd) as well as Chlorophyll-a (Chl-a) and total phenol concentration. The range and the average values of nutrient salts (μM) in El Dekhila harbour were: 0.10–3.10 (1.50 ± 1.0), 0.6–52.60 (18.50 ± 16.4), 0.40–10.0 (3.6 ± 2.9) and 3.5–113.0 (32.3 ± 30.9) for PO4-P, NH4-N, NO2-N, NO3-N and SiO4-Si, respectively. While in the Abu Talat region, they were 0.1–1.20 (0.32 ± 0.30), 1.34–10.8 (4.61 ± 2.5), 0.07–1.18 (0.38 ± 0.3), 0.31–30.19 (7.69 ± 8.0) and 0.10–14.44 (4.56 ± 4.0) for the same parameters, respectively. The studied metals in the two regions arranged in the following order: Fe > Zn > Mn > Pb > Cu > Cd. The metals concentration in El Dekhila harbour was two to sixfolds higher than those recorded in the Abu Talat region. The levels of Chl-a content (0.22–26.97 µg/L) and total phenol concentration (0.75–70.75 µg/L) revealed wide variations from site to another. The ecological risk of nitrogen and phosphorus data using two trophic state indices showed that the study area lies between low and high trophic state. El Dekhila harbour has the lowest water quality compared with those computed in the Abu Talat area where the difference ranged from two to five times in WQI. Analysis of the test of variance (ANOVA) showed that the mean concentrations for all parameters across the two regions differed significantly at a significance level of 0.05.