Being aware of the potential risks of heavy metals in soils is important. In Omaha, 125 years of lead smelting at the American Smelting and Refining Company (ASARCO) resulted in elevated soil lead concentrations (around 400 ppm) near residential housing. Furthermore, a study conducted on an urban garden soil near a railroad station in Lincoln found that consumption of one serving of garden-grown lettuce would result in lead and arsenic intake above the EPA limits for human consumption.
Soils typically have a range of naturally occurring heavy metals. However, heavy metals sourced from human activity can produce concentrations resulting in increased exposure risks. Therefore, targeted cleanup methods are imperative.
Soil is like a sponge. Metals end up bound to organic matter and minerals, accumulating with time.
The three prominent metals in contaminated soils are lead, arsenic, and cadmium. Arsenic can be naturally enriched in phosphate used for fertilizers. Cadmium becomes enriched from zinc mining. Finally, lead was historically sourced from leaded gasoline and paint. These household items were phased out decades ago. However, soils can have a naturally high background from decades of gas combustion and lead paint chipping from old buildings. Additionally, Lead-arsenic pesticides were even used for around 60 years to treat coddling moths in orchards throughout the United States.
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