Question

Copper (Cu) was used as a fungicide in citrus orchards that are being considered for a stormwater retention project as part of the Everglades (Florida) restoration effort. Copper accumulates in apple snails, a primary food source of the federally endangered bird called the Everglades Snail Kite. A professional engineer at BTA Inc. is considering two former citrus production areas for construction of a stormwater treatment area – a 1,500-acre site with soils having a Cu content of 220 ppm and a 2000-acre site with 160 lb of Cu uniformly distributed in the top 6 – 8 in. of soil. Which site should the engineer recommend for the project if the ecological threshold to support the Everglades Snail Kite is 85 mg Cu/kg? Ecological threshold means that the soil concentration of copper cannot exceed this value. Assume the plow layer of soil (upper 6 – 8 in.) for the 2,000-acre site weighs 2,000,000 lb. [Note: 1 inch = 2.54 cm

Answer 1

Solution:

For Cu= 220 ppm on the 1,500-acre site:

For 160 lbs uniformly distributed in top 6-8 inches of soil on the 2,000 acre site:

The engineer should recommend the 2000 acre site for the project.