PEC_soil. pfm 0.3-7

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)
-

- - - -

Author

- -Johannes Ranke - - -

Calculate predicted environmental concentrations in soil