Question

A lake with a cross-sectional area of 1km2 and a depth of 50 meters has a euphotic zone that extends 15meters blow the surface. What is the maximum weight of the biomass (in grams of carbon) that can be decomposed by aerobic bacteria in the water column of the lake below the euphotic zone during the summer when there is no circulation with the upper layer? The bacterial decomposition is (CH2O)n + nO2  nCO2 + nH2O The solubility of oxygen in pure water saturated with air at 20°C is 8.9 ppm-O2

Answer 1

The depth of lake is 50 meters.

The euphotic zone extends 15 meters blow the surface.

The effective depth of lake is meters.

The area of lake is 1 km² or

Volume of lake is

The solubility of oxygen in pure water saturated with air at 20°C is 8.9 ppm-O2

It means that will contain of oxygen.

The maximum weight of the biomass (in grams of carbon) that can be decomposed by 32 g O2 is 12 g C.

The maximum weight of the biomass (in grams of carbon) that can be decomposed by 311.5 g O2 is g C.