Question

The concentration of copper in the surface organic layer of a forest soil is 37 ppm (w/w), and in the underlying mineral layer is 17 ppm. The bulk densities of these two layers are 0.36 and 1.22 g mL^-1, respectively. The very low density of the surface material occurs because it consists in large part of partially degraded organic material and there is very little of the heavier mineral matter. Which of these two layers has the higher copper concentration per unit volume?

Answer 1

let us take 1ml volume ,

mass of organic layer = volume x density = 1ml x 0.36 g/ml = 0.36 g

mass of mineral layer = 1ml x 1.22 g/ml = 1.22 g

( 1ppm = 10^-6)

copper mass in organic layer = ( 37 x 10^-6) x 0.36 g = 1.332 x 10^-5 g

copper mass in mineral layer = ( 17 x 10^-6) x ( 1.22g) = 2 x 10^-5 g

For same volume of 1ml we see minerla layer has high amount of copper compared to organic layer

Thus per unit volume we see that Copper concentration is high in mineral layer