Equation 18 (non-radionuclides), equation 19 (radionuclides), and Table 13 present the exposure variables for the surface water/groundwater produce ingestion pathway. The produce ingestion pathway is conducted for the agricultural pathway only.
Parameter
Units
Agricultural
|
Non-radionuclide chemical concentration in water = Cwn
mg/L
Chemical-specific
Radionuclide chemical concentration in water = Cwr
pCi/L
Chemical-specific
Irrigation rate = rirr
L/m2 day
2.08
(Kennedy and Strenge 1992)
Irrigation period = firr
unitless
0.25
(3 months)
Soil to plant uptake factor (wet) = BVwet
kg/kg
Chemical-specific
Mass loading factor = MLF
unitless
0.26
(Pinder and McLeod 1989)
Effective removal rate = ër
1/day
ël+ëhl
Soil leaching rate = ël
1/day
2.7E-5
(NCRP 1989)
Radionuclide half-life = ëhl
1/day
Chemical-specific
Long-term deposition and buildup = tb
day
10950
(NCRP 1985)
Areal density for root zone = P
kg/m2
240
(Hoffman et al. 1982)
Interception fraction = If
unitless
0.42
(Miller 1980)
Translocation factor = T
unitless
1
(McKone 1994)
Decay for removal on produce = ëE
1/day
ël+0.693/tw
(NCRP 1989)
Weathering half-life = tw
1/day
14
(NCRP 1985)
Above ground exposure time = tv
days
60
(NCRP 1985)
Plant yield (wet) = Yv
kg/m2
2
(NCRP 1985)
Diet fraction = FIv
unitless
0.4
(EPA 1989b)
Ingestion rate = IRv
kg/d
0.2
(EPA 1989b)
Exposure frequency = EF
d/year
350
(EPA 1989a)
Exposure duration = ED
years
30
(EPA 1989a)
Body weight (adult) = BW
kg
70
(EPA 1989a)
Conversion Factor = CF2
days/yr
365
Lifetime = LT
years
70
(EPA 1989a)
Averaging time = AT
years
LT (carcinogen)
ED (noncarcinogen)
(18)