Protocol for the Derivation of Environmental and Human ... - CCME

Appendix E
The concentration of a contaminant in erosional soil that will raise the receiving soil concentration above
a given level can be calculated by assuming a background concentration in the receiving soil and
estimating the quantity of soil originating from a hypothetical industrial site. With appropriate input
parameters for soil, climate, and site characteristics, EPIC can estimate the quantity of soil eroded from
the site. Residential/parkland/commercial land use is the receiving soil.
4.2 Erosion/Productivity Impact Calculator input parameters
A soil with 3% organic carbon and a sandy loam texture (73% sand, 19% silt and 8% clay) was chosen
as representative soil susceptible to erosion. A 1 hectare site with 1% slope and 650 kg/ha of
vegetative surface cover was modeled.
Two climate scenarios were run. Climate data from Lethbridge, Alberta was used to estimate potential
erosion where wind is the dominant erosive force. Climatic data from Halifax, Nova Scotia, was used to
simulate erosion where rainfall was the dominant force. EPIC estimated the following losses over a five
year period:
Soil Lost by Erosion (t/ha)
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Site Wind Water Total
Lethbridge 13.2 3.3 16.5
Halifax 0.0 11.3 11.3
The two values were averaged to produce an estimated loss by erosion of 13.9 t/ha.
Assuming a bulk density for the eroded material of 1 t/m 3 and a depositional area equal to the source
area, the depth of the deposited material (D d ) can be evaluated to 0.14 cm using:
where
D d = E/(? b × 10 2 ) [1]
E is the mass of deposited material = 13.9 t/ha
? b is the bulk density = 1 t/m 3
Assuming a bulk density of 1 t/m 3 for receiving soil and a mixing depth of 2 cm, the final concentration
of the receiving soil after mixing can be calculated by:
Cm = {(2 - D d ) BSC) + (D d × C i )}/2 [2]
where
Cm is the concentration of contaminant in the receiving soil after mixing (µg/g).
BSC is the background concentration of the contaminant in the receiving soil (µg/g).
C i is the concentration of contaminant in the eroded soil (µg/g).
Substituting the value calculated for D d in equation [2] and replacing C m with SQG R/P/C, that equation
can be rearranged to calculate the concentration in soil eroded from the industrial site that will raise the