Metal contamination and infiltration into the soil at refuse dump sites in Awka, Nigeria.

Awka has been the site of increased human activities since it became a state capital in 1991. Because refuse dumps have hitherto been a disregarded environmental menace in Nigeria, the authors sought to find out how much of the current environmental metal pollutant load comes from refuse dumps. They investigated the metal contamination of the refuse dumps in Awka. The authors collected four soil samples (from the surface and from depths of 0.45 m, 0.90 m, and 1.35 m) from 5 dumpsites digested with nitric acid and perchloric acid, and they analyzed iron, sodium, arsenic, lead, magnesium, potassium, cobalt, zinc, nickel, copper, chromium, and cadmium by using an atomic absorption spectrophotometer. Sites A and C showed the highest levels of arsenic (2300 mg/kg) and lead (2467 mg/kg), respectively. Site D had highest level of both iron (72,200 mg/kg) and sodium (3561 mg/kg), whereas Site E had the lowest level of lead (572 mg/kg). The metal levels exceed the limits set forth by the US Environmental Protection Agency. This study suggests that the refuse dumps in Awka may increase the level of environmental heavy metals in Nigeria.