PEC_soil. pfm 0.3-8

Usage

PEC_soil(rate, rate_units = "g/ha", interception = 0, mixing_depth = 5,
+  PEC_units = "mg/kg", PEC_pw_units = "mg/L", interval = NA,
+  n_periods = Inf, tillage_depth = 20, chent = NA, DT50 = NA,
+  Koc = NA, Kom = Koc/1.724, t_avg = 0, scenarios = c("default",
+  "EFSA_2015"), porewater = FALSE)

+ +

Arguments

rate: Application rate in units specified below
rate_units: Defaults to g/ha
interception: The fraction of the application rate that does not reach the soil
mixing_depth: Mixing depth in cm
PEC_units: Requested units for the calculated PEC. Only mg/kg currently supported
PEC_pw_units: Only mg/L currently supported
interval: Period of the deeper mixing, defaults to 365, which is a year if +rate units are in days
n_periods: Number of periods to be considered for long term PEC calculations
tillage_depth: Periodic (see interval) deeper mixing in cm
chent: An optional chent object holding substance specific information. Can +also be a name for the substance as a character string
DT50: If specified, overrides soil DT50 endpoints from a chent object +If DT50 is not specified here and not available from the chent object, zero +degradation is assumed
Koc: If specified, overrides Koc endpoints from a chent object
Kom: Calculated from Koc by default, but can explicitly be specified +as Kom here
t_avg: Averaging times for time weighted average concentrations
scenarios: If this is 'default', the DT50 will be used without correction +and soil properties as specified in the REACH guidance (R.16, Table +R.16-9) are used for porewater PEC calculations. If this is "EFSA_2015", +the DT50 is taken to be a modelling half-life at 20°C and pF2 (for when +'chents' is specified, the DegT50 with destination 'PECgw' will be used), +and corrected using an Arrhenius activation energy of 65.4 kJ/mol. Also +model and scenario adjustment factors from the EFSA guidance are used.
porewater: Should equilibrium porewater concentrations be estimated +based on Kom and the organic carbon fraction of the soil instead of total +soil concentrations? Based on equation (7) given in the PPR panel opinion +(EFSA 2012, p. 24) and the scenarios specified in the EFSA guidance (2015, +p. 13).

+ +

Value

+ +

+The predicted concentration in soil +

+ +

Description

+ +

This is a basic calculation of a contaminant concentration in bulk soil +based on complete, instantaneous mixing. If an interval is given, an +attempt is made at calculating a long term maximum concentration using +the concepts layed out for example in the PPR panel opinion (EFSA 2012).

+ +

Details

+ +

This assumes that the complete load to soil during the time specified by +'interval' (typically 365 days) is dosed at once. As in the PPR panel +opinion cited below (PPR panel 2012), only temperature correction using the +Arrhenius equation is performed.

+ +

Total soil and porewater PEC values for the scenarios as defined in the EFSA +guidance (2015, p. 13) can easily be calculated.

+ +

Note

+ +

If temperature information is available in the selected scenarios, as + e.g. in the EFSA scenarios, the DT50 for groundwater modelling + (destination 'PECgw') is taken from the chent object, otherwise the DT50 + with destination 'PECsoil'.

+ +

References

+ +

EFSA Panel on Plant Protection Products and their Residues (2012) + Scientific Opinion on the science behind the guidance for scenario + selection and scenario parameterisation for predicting environmental + concentrations of plant protection products in soil. EFSA Journal + 10(2) 2562, doi:10.2903/j.efsa.2012.2562

+ +

EFSA (European Food Safety Authority) (2015) EFSA guidance document for + predicting environmental concentrations of active substances of plant + protection products and transformation products of these active substances + in soil. EFSA Journal 13(4) 4093 + doi:10.2903/j.efsa.2015.4093

+ +

Examples

PEC_soil(100, interception = 0.25)
+     scenario
+t_avg default
+    0     0.1
+
+
+# This is example 1 starting at p. 79 of the EFSA guidance (2015)
+PEC_soil(1000, interval = 365, DT50 = 250, t_avg = c(0, 21),
+               scenarios = "EFSA_2015")
+     scenario
+t_avg      CTN      CTC      CTS
+   0  21.96827 11.53750 9.145259
+   21 21.78517 11.40701 9.017370
+
+PEC_soil(1000, interval = 365, DT50 = 250, t_av = c(0, 21),
+               Kom = 1000, scenarios = "EFSA_2015", porewater = TRUE)
+     scenario
+t_avg       CLN       CLC       CLS
+   0  0.7589401 0.6674322 0.9147861
+   21 0.7506036 0.6590345 0.8987279
+
+
+# The following is from example 4 starting at p. 85 of the EFSA guidance (2015)
+# Metabolite M2
+# Calculate total and porewater soil concentrations for tier 1 scenarios
+# Relative molar mass is 100/300, formation fraction is 0.7 * 1
+results_pfm <- PEC_soil(100/300 * 0.7 * 1 * 1000, interval = 365, DT50 = 250, t_avg = c(0, 21),
+                        scenarios = "EFSA_2015")
+results_pfm_pw <- PEC_soil(100/300 * 0.7 * 1000, interval = 365, DT50 = 250, t_av = c(0, 21),
+                           Kom = 100, scenarios = "EFSA_2015", porewater = TRUE)

+ +

Calculate predicted environmental concentrations in soil