Proximate and Mineral Composition of Talinum triangulare (Waterleaf) from Quarry and Non-Quarry Sites in Port Harcourt: Implications for Nutrition and Food Safety

Background: Quarrying activities have been shown to influence the geochemical properties of surrounding soils, potentially affecting edible plants' nutrient and heavy metal composition. Talinum triangulare (waterleaf), a commonly consumed leafy vegetable in Nigeria, may indicate environmental contamination due to its widespread cultivation and consumption. Objectives: This research focused on assessing the proximate and mineral composition of waterleaf samples from a quarry site in Eleme and a non-quarry site in Igwuruta, Port Harcourt, Nigeria, to assess the influence of quarrying on nutritional quality and heavy metal content. Methods: Waterleaf samples were collected from both sites, sun-dried, and analyzed for proximate composition (carbohydrates, protein, moisture, ash, fat, fiber) using AOAC methods. Mineral and heavy metal contents (potassium, calcium, magnesium, sodium, phosphorus, copper, manganese, zinc, iron, lead, cadmium, nickel) were determined via atomic absorption spectroscopy and flame photometry. Data were analyzed using one-way ANOVA (p < 0.05). Results: Quarry site samples showed slightly higher carbohydrate (56.34%) and ash (8.47%) contents but lower protein (11.85%), moisture (5.67%), and fat (6.53%) compared to control samples (54.10%, 13.30%, 6.39%, 7.34%, 7.62%, respectively). Fiber content remained consistent (~11%). Essential minerals like potassium, calcium, and iron were present appreciably, with quarry site samples showing elevated levels of copper (1.58 mg/100g) and manganese (5.35 mg/100g). Notably, lead (0.21 mg/100g), cadmium (0.52 mg/100g), and nickel (0.38 mg/100g) were detected exclusively in quarry samples (dry weight). Approximate fresh weight conversions (assuming 90% moisture) yield cadmium (0.052 mg/100g) and nickel (0.038 mg/100g) exceeding WHO/FAO limits (0.02 mg/100g for Cd, 0.1 mg/100g for Ni), while lead (0.021 mg/100g) is within limits (<0.1 mg/kg). Conclusions: Although waterleaf remains an important nutrient source, heavy metals from the quarry site sample indicate health risks. Regular monitoring of crops grown in such industrially impacted areas is recommended.