can you explain each parts

(2) A community has stockpiled biosolids in a storage lagoon. The lagoon needs to be cleaned and the biosolids disposed of to make room for a plant expansion. The metals concentrations in the lagoon are as follows: As (45 mg /kg),Cd(30mg/kg), Cu (1,200 mg/kg), Pb (250 mg/kg), Hg (5 mg/kg), Ni (350 mg/kg), Se(15mg/kg) and Zn(3,100mg/kg). It has been determined from comparison with the appropriate limits that all metal concentrations except As and Zn concentrations are below the limit for exceptional quality biosolids (i.e., biosolids that meet metal standards, Class A pathogen reduction standards, and vector reduction standards). Hence, calculate the allowable annual biosolids loading rates for: (a) As, given that its annual pollutant loading rate is 2kg/ ha.y (I point). (b) Zn, given that its annual pollutant loading rate is 140kg/ ha.y (I point). (c) Compare both biosolids loading rates and determine the limiting rate ( 1 point)