Calculate PEC surface water due to drainage as in Exposit 3

This is a reimplementation of the calculation described in the Exposit 3.02 spreadsheet file, in the worksheet "Konzept Drainage". Although there are four groups of compounds ("Gefährdungsgruppen"), only one distinction is made in the calculations, between compounds with low mobility (group 1) and compounds with modest to high mobility (groups 2, 3 and 4). In this implementation, the group is derived only from the Koc, if not given explicitly. For details, see the discussion of the function arguments below.

PEC_sw_exposit_drainage(
  rate,
  interception = 0,
  Koc = NA,
  mobility = c(NA, "low", "high"),
  DT50 = Inf,
  t_drainage = 3,
  V_ditch = 30,
  V_drainage = c(spring = 10, autumn = 100),
  dilution = 2
)

Source

Excel 3.02 spreadsheet available from https://www.bvl.bund.de/SharedDocs/Downloads/04_Pflanzenschutzmittel/zul_umwelt_exposit.html

Arguments

rate

The application rate in g/ha

interception

The fraction intercepted by the crop

Koc

The sorption coefficient to soil organic carbon used to determine the mobility. A trigger value of 550 L/kg is used in order to decide if Koc >> 500.

mobility

Overrides what is determined from the Koc.

DT50

The soil half-life in days

t_drainage

The time between application and the drainage event, where degradation occurs, in days

V_ditch

The volume of the ditch is assumed to be 1 m * 100 m * 30 cm = 30 m3

V_drainage

The drainage volume, equivalent to 1 mm precipitation on 1 ha for spring/summer or 10 mm for autumn/winter/early spring.

dilution

The dilution factor

Value

A list containing the following components

perc_runoff

The runoff percentages for dissolved and bound substance

runoff

A matrix containing dissolved and bound input for the different distances

PEC_sw_runoff

A matrix containing PEC values for dissolved and bound substance for the different distances. If the rate was given in g/ha, the PECsw are in microg/L.

See also

perc_runoff_exposit for runoff loss percentages and perc_runoff_reduction_exposit for runoff reduction percentages used

Examples

  PEC_sw_exposit_drainage(500, Koc = 150)
#> $perc_drainage_total
#> spring autumn 
#>    0.2    1.0 
#> 
#> $perc_peak
#> spring autumn 
#>   12.5   25.0 
#> 
#> $PEC_sw_drainage
#>   spring   autumn 
#> 1.562500 4.807692 
#>