Methods of Analyzing Heavy Metals in Water and Sampling Procedure Across Southern Nigeria

Heavy metals, existing in diverse chemical states, present analytical challenges requiring preconcentration techniques before determination. The study aims to evaluate heavy metal contamination in water sources across Southern Nigeria, employing rigorous analytical and sampling methodologies. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used for the multi-element analysis, capitalizing on its broad linear range (4–6 orders of magnitude) and reduced matrix interference compared to atomic absorption spectroscopy (AAS). Sampling followed strict protocols: containers were pre-cleaned via acid-wash (nitrate/phosphorus) or detergent-rinse (conductivity, pH, metals), and water was collected from mid-current points across 13 sites in Edo, Cross River, Akwa-Ibom, and Delta States. Results revealed arsenic levels exceeding WHO guidelines in SP4 (Obaretin River, Edo; 0.103 mg/L), SP11 (Esuk Nsidung, Cross River; 0.165 mg/L), and SP13 (Okada River, Edo; 0.109 mg/L). Aluminum concentrations were elevated in SP4 (1.766 mg/L), SP8 (1.112 mg/L), and SP10 (1.351 mg/L). Other metals (Cd, Co, Cr, Cu, Pb, Zn) generally fell within acceptable limits. Iron was highest in SP6 (3.002 mg/L), while manganese remained below thresholds. The presence of arsenic above safety limits highlights pollution risks, potentially linked to anthropogenic activities or geological factors. These results underscore significant health risks from arsenic (carcinogenic, linked to IQ reduction) and lead (neurotoxic), emphasizing vulnerabilities in children due to higher exposure rates and developmental sensitivity. Regulatory failures exacerbate these risks, as evidenced by undocumented toxins in consumer goods and inadequate safety labeling. The study concludes that while most sites are relatively safe, targeted interventions by regulatory and state agencies are crucial to safeguard drinking water, alongside stricter industrial regulations and public awareness campaigns.