# Calculate PEC surface water at FOCUS Step 1
This is a reimplementation of the FOCUS Step 1 and 2 calculator version
3.2, authored by Michael Klein, in R. Note that results for multiple
applications should be compared to the corresponding results for a
single application. At current, this is not done automatically in this
implementation. Only Step 1 PECs are calculated. However, input files
can be generated that are suitable as input for the FOCUS calculator.
## Usage
``` r
PEC_sw_focus(
parent,
rate,
n = 1,
i = NA,
comment = "",
met = NULL,
f_drift = NA,
f_rd = 0.1,
scenario = FOCUS_Step_12_scenarios$names,
region = c("n", "s"),
season = c(NA, "of", "mm", "js"),
interception = c("no interception", "minimal crop cover", "average crop cover",
"full canopy"),
met_form_water = TRUE,
txt_file = "pesticide.txt",
overwrite = FALSE,
append = FALSE
)
```
## Arguments
- parent:
A list containing substance specific parameters, e.g. conveniently
generated by
[chent_focus_sw](https://pkgdown.jrwb.de/pfm/reference/chent_focus_sw.md).
- rate:
The application rate in g/ha. Overriden when applications are given
explicitly
- n:
The number of applications
- i:
The application interval
- comment:
A comment for the input file
- met:
A list containing metabolite specific parameters. e.g. conveniently
generated by
[chent_focus_sw](https://pkgdown.jrwb.de/pfm/reference/chent_focus_sw.md).
If not NULL, the PEC is calculated for this compound, not the parent.
- f_drift:
The fraction of the application rate reaching the waterbody via drift.
If NA, this is derived from the scenario name and the number of
applications via the drift data defined by the
[FOCUS_Step_12_scenarios](https://pkgdown.jrwb.de/pfm/reference/FOCUS_Step_12_scenarios.md)
- f_rd:
The fraction of the amount applied reaching the waterbody via
runoff/drainage. At Step 1, it is assumed to be 10%, be it the parent
or a metabolite
- scenario:
The name of the scenario. Must be one of the scenario names given in
[FOCUS_Step_12_scenarios](https://pkgdown.jrwb.de/pfm/reference/FOCUS_Step_12_scenarios.md)
- region:
'n' for Northern Europe or 's' for Southern Europe. If NA, only Step 1
PECsw are calculated
- season:
'of' for October to February, 'mm' for March to May, and 'js' for June
to September. If NA, only step 1 PECsw are calculated
- interception:
One of 'no interception' (default), 'minimal crop cover', 'average
crop cover' or 'full canopy'
- met_form_water:
Should the metabolite formation in water be taken into account? This
can be switched off to check the influence and to compare with
previous versions of the Steps 12 calculator
- txt_file:
the name, and potentially the full path to the Steps.12 input text
file to which the specification of the run(s) should be written
- overwrite:
Should an existing file a the location specified in `txt_file` be
overwritten? Only takes effect if append is FALSE.
- append:
Should the input text file be appended, if it exists?
## Note
The formulas for input to the waterbody via runoff/drainage of the
parent and subsequent formation of the metabolite in water is not
documented in the model description coming with the calculator. As one
would expect, this appears to be (as we get the same results) calculated
by multiplying the application rate with the molar weight correction and
the formation fraction in water/sediment systems.
Step 2 is not implemented.
## References
FOCUS (2014) Generic guidance for Surface Water Scenarios (version 1.4).
FOrum for the Co-ordination of pesticde fate models and their USe.
http://esdac.jrc.ec.europa.eu/public_path/projects_data/focus/sw/docs/Generic%20FOCUS_SWS_vc1.4.pdf
Website of the Steps 1 and 2 calculator at the Joint Research Center of
the European Union: http://esdac.jrc.ec.europa.eu/projects/stepsonetwo
## Examples
``` r
# Parent only
dummy_1 <- chent_focus_sw("Dummy 1", cwsat = 6000, DT50_ws = 6, Koc = 344.8)
PEC_sw_focus(dummy_1, 3000, f_drift = 0)
#> $f_drift
#> [1] 0
#>
#> $eq_rate_drift_s
#> [1] 3000
#>
#> $eq_rate_rd_s
#> [1] 3000
#>
#> $eq_rate_rd_parent_s
#> [1] NA
#>
#> $input_drift_s
#> [1] 0
#>
#> $input_rd_s
#> [1] 300
#>
#> $f_rd_sw
#> [1] 0.6850566
#>
#> $f_rd_sed
#> [1] 0.3149434
#>
#> $PEC
#> type
#> Time PECsw TWAECsw PECsed TWAECsed
#> 0 6.850566e+02 NA 2.362075e+03 NA
#> 1 6.103161e+02 647.68635 2.104370e+03 2233.2225
#> 2 5.437298e+02 612.03420 1.874780e+03 2110.2939
#> 4 4.315586e+02 548.76030 1.488014e+03 1892.1255
#> 7 3.051580e+02 469.88375 1.052185e+03 1620.1592
#> 14 1.359325e+02 339.57370 4.686951e+02 1170.8501
#> 21 6.055102e+01 257.45458 2.087799e+02 887.7034
#> 28 2.697241e+01 203.47173 9.300089e+01 701.5705
#> 42 5.352005e+00 140.10377 1.845371e+01 483.0778
#> 50 2.123945e+00 118.24602 7.323361e+00 407.7123
#> 100 6.585062e-03 59.30629 2.270529e-02 204.4881
#>
#> $PEC_sw_max
#> [1] 685.0566
#>
#> $PEC_sed_max
#> [1] 2362.075
#>
# Metabolite
new_dummy <- chent_focus_sw("New Dummy", mw = 250, Koc = 100)
M1 <- chent_focus_sw("M1", mw = 100, cwsat = 100, DT50_ws = 100, Koc = 50,
max_ws = 0, max_soil = 0.5)
PEC_sw_focus(new_dummy, 1000, scenario = "cereals, winter", met = M1)
#> $f_drift
#> [1] 0.02759
#>
#> $eq_rate_drift_s
#> [1] 0
#>
#> $eq_rate_rd_s
#> [1] 200
#>
#> $eq_rate_rd_parent_s
#> [1] 0
#>
#> $input_drift_s
#> [1] 0
#>
#> $input_rd_s
#> [1] 20
#>
#> $f_rd_sw
#> [1] 0.9375
#>
#> $f_rd_sed
#> [1] 0.0625
#>
#> $PEC
#> type
#> Time PECsw TWAECsw PECsed TWAECsed
#> 0 62.50000 NA 31.25000 NA
#> 1 62.06828 62.28414 31.03414 31.14207
#> 2 61.63954 62.06890 30.81977 31.03445
#> 4 60.79093 61.64158 30.39547 30.82079
#> 7 59.53987 61.00800 29.76994 30.50400
#> 14 56.71995 59.56326 28.35997 29.78163
#> 21 54.03358 58.16414 27.01679 29.08207
#> 28 51.47444 56.80902 25.73722 28.40451
#> 42 46.71404 54.22460 23.35702 27.11230
#> 50 44.19417 52.81945 22.09709 26.40973
#> 100 31.25000 45.08422 15.62500 22.54211
#>
#> $PEC_sw_max
#> [1] 62.5
#>
#> $PEC_sed_max
#> [1] 31.25
#>
```
