Determination of Heavy Metal Levels in Soil Samples from Selected Areas in Nairobi County

Heavy metals play a dual role in soil ecosystems, being essential for biological and biochemical processes crucial for crop development, with elements such as zinc, copper, and iron serving as vital micronutrients for plant growth. Zinc, for instance, is fundamental for enzyme function, protein synthesis, and immune response. However, the presence of these elements in excessive concentrations, often a direct consequence of human activities, can lead to significant toxicity, thereby posing a substantial threat to both environmental integrity and ecosystem health. This inherent tension between essentiality and toxicity underscores the complex challenge of environmental management, which must focus on maintaining concentrations within a beneficial-to-safe range rather than pursuing outright elimination. This approach is critical for establishing appropriate environmental thresholds and addressing the multifaceted nature of pollution. Soil contamination by heavy metals represents a major environmental concern due to their inherent persistence in the environment and their propensity to accumulate within the food chain. Primary sources of such contamination include industrial operations, improper waste disposal practices, agricultural runoff, and vehicular emissions. This study specifically analyzed heavy metal concentrations in soil samples collected from petrol stations and a designated control site within Nairobi County. The investigation focused on quantifying levels of lead, cadmium, chromium, and nickel using atomic absorption spectroscopy. The findings revealed distinct contamination trends directly linked to fuel-related activities, providing valuable information for the development of effective environmental management strategies and targeted remediation efforts.