Water quality, heavy metal contamination and health risk assessment of surface water bodies of Mohammedia prefecture, Morocco

Abstract

Research work on surface water bodies in Morocco has been in majority restricted to physicochemical and biological concentration. Hence, this study was conducted to address the existing research gap by evaluating heavy metal contamination and its associated risk assessment in surface water bodies, in Mohammedia prefecture, Morocco. A total of 22 water samples were evaluated regarding physicochemical factors and heavy metals. The parameters analyzed are pH, temperature (T), electrical conductivity (EC), total dissolved solids (TDS), calcium (Ca²⁺), Sodium (Na⁺), Potassium (K⁺), Ammonia (NH⁺), dissolved oxygen (DO), Sulphate (SO₄²⁻), nitrite (NO²⁻), nitrate (NO³⁻), phosphate (PO₄³⁻), total phosphate (TP), total kjeldahl nitrogen (TKN), cadmium (Cd), copper (Cu), Iron (Fe), lead (Pb), and zinc (Zn). Overall water quality (Ow) and status of contamination presented the water quality and pollution quantitatively. Carcinogenic and noncarcinogenic risks were estimated for health risk assessment. Ca²⁺ was the most abundant cation, and SO₄³⁻ was the most abundant anion. Heavy metal concentrations were within permissible limits. Ow was good in terms of being suitable for parameters, i.e., <1 except for NH+. Which indicated water quality in the category of “highly polluted” >2.5. Pollution index (PI) indicated high pollution (14–74) at S3, S4, S5, and S6 sample points. In addition, Pb was a significant contributor to deteriorating water quality, with individual contributions ranging from 1 to 12 at sites S1, S2, and S3. For heavy metal hazards, i.e., adverse health effects, Hazard Quotient (HQ) (0.0002–0.01) was <1 for sample points, and Hazard Index (HI) (0.007–0.01) had a similar trend. They were inferring no significant non-carcinogenic health impact on its consumers. Carcinogenic risk (CR) was found to be within acceptable limits for CD, Cu, Pb, and Zn, i.e., 10⁻⁴ to 10⁻⁶. At points S2, S3, and S4, the carcinogenic index (CI) was above the acceptable limit, with values ranging from 1 × 10⁻³ to 7.9 × 10⁻³ attributed to Fe. Therefore, according to the findings of this research, the water quality is not suitable for direct consumption in its current state. Hence the study recommends treatment of surface water bodies prior to consumption.