Calculate PEC surface water due to runoff and erosion as in Exposit 3

This is a reimplementation of the calculation described in the Exposit 3.02 spreadsheet file, in the worksheet "Konzept Runoff".

Usage

PEC_sw_exposit_runoff(
  rate,
  interception = 0,
  Koc,
  DT50 = set_units(Inf, "d"),
  t_runoff = set_units(3, "days"),
  exposit_reduction_version = c("3.02", "3.01a", "3.01a2", "2.0"),
  V_ditch = set_units(30, "m3"),
  V_event = set_units(100, "m3"),
  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
DT50: The soil half-life in days
t_runoff: The time between application and the runoff event, where degradation occurs, in days
exposit_reduction_version: The version of the reduction factors to be used. "3.02" is the current version used in Germany, "3.01a" is the version with additional percentages for 3 m and 6 m buffer zones used in Switzerland. "3.01a2" is a version introduced for consistency with previous calculations performed for a 3 m buffer zone in Switzerland, with the same reduction being applied to the dissolved and the bound fraction.
V_ditch: The volume of the ditch is assumed to be 1 m * 100 m * 30 cm = 30 m3
V_event: The unreduced runoff volume, equivalent to 10 mm precipitation on 1 ha
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.

Details

It is recommened to specify the arguments rate, Koc, DT50, t_runoff, V_ditch and V_event using units::units from the units package.

Examples

  PEC_sw_exposit_runoff(500, Koc = 150)
#> $perc_runoff
#> dissolved     bound 
#>     0.248     0.001 
#> 
#> $runoff
#>           dissolved       bound       total
#> No buffer 1.240 [g] 0.00500 [g] 1.24500 [g]
#> 5 m       0.744 [g] 0.00300 [g] 0.74700 [g]
#> 10 m      0.496 [g] 0.00075 [g] 0.49675 [g]
#> 20 m      0.248 [g] 0.00025 [g] 0.24825 [g]
#> 
#> $PEC_sw_runoff
#>                 dissolved              bound           total
#> No buffer 4.769231 [µg/L] 0.019230769 [µg/L] 4.788462 [µg/L]
#> 5 m       4.133333 [µg/L] 0.016666667 [µg/L] 4.150000 [µg/L]
#> 10 m      3.542857 [µg/L] 0.005357143 [µg/L] 3.548214 [µg/L]
#> 20 m      2.480000 [µg/L] 0.002500000 [µg/L] 2.482500 [µg/L]
#> 
  PEC_sw_exposit_runoff(600, Koc = 10000, DT50 = 195, exposit = "3.01a")
#> $perc_runoff
#> dissolved     bound 
#>     0.037     0.159 
#> 
#> $runoff
#>                dissolved          bound          total
#> No buffer 0.21964521 [g] 0.94388078 [g] 1.16352600 [g]
#> 3 m       0.16473391 [g] 0.66071655 [g] 0.82545046 [g]
#> 5 m       0.13178713 [g] 0.56632847 [g] 0.69811560 [g]
#> 6 m       0.12080487 [g] 0.42474635 [g] 0.54555122 [g]
#> 10 m      0.08785809 [g] 0.14158212 [g] 0.22944020 [g]
#> 20 m      0.04392904 [g] 0.04719404 [g] 0.09112308 [g]
#> 
#> $PEC_sw_runoff
#>                  dissolved            bound            total
#> No buffer 0.8447893 [µg/L] 3.6303107 [µg/L] 4.4751000 [µg/L]
#> 3 m       0.7844472 [µg/L] 3.1462693 [µg/L] 3.9307165 [µg/L]
#> 5 m       0.7321507 [µg/L] 3.1462693 [µg/L] 3.8784200 [µg/L]
#> 6 m       0.7106169 [µg/L] 2.4985080 [µg/L] 3.2091248 [µg/L]
#> 10 m      0.6275578 [µg/L] 1.0113008 [µg/L] 1.6388586 [µg/L]
#> 20 m      0.4392904 [µg/L] 0.4719404 [µg/L] 0.9112308 [µg/L]
#>