% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/PEC_sw_focus.R
\name{PEC_sw_focus}
\alias{PEC_sw_focus}
\title{Calculate FOCUS Step 1 PEC surface water}
\usage{
PEC_sw_focus(parent, rate, n = 1, i = NA, met = NULL, f_drift = NA,
  f_rd = 0.1, scenario = FOCUS_Step_12_scenarios$names)
}
\arguments{
\item{parent}{A list containing substance specific parameters, e.g.
conveniently generated by \code{\link{chent_focus_sw}}.}

\item{rate}{The application rate in g/ha. Overriden when
applications are given explicitly}

\item{n}{The number of applications}

\item{i}{The application interval}

\item{met}{A list containing metabolite specific parameters.  e.g.
conveniently generated by \code{\link{chent_focus_sw}}.  If not NULL,
the PEC is calculated for this compound, not the parent.}

\item{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
\code{\link{FOCUS_Step_12_scenarios}}}

\item{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}

\item{scenario}{The name of the scenario. Must be one of the scenario
names given in \code{\link{FOCUS_Step_12_scenarios}}}
}
\description{
This is reimplementation of Step 1 of the FOCUS Step 1 and 2 calculator
version 3.2, authored by Michael Klein. 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.
}
\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.
}
\examples{
# Parent only
dummy_1 <- chent_focus_sw(cwsat = 6000, DT50_ws = 6, Koc = 344.8)
PEC_sw_focus(dummy_1, 3000, f_drift = 0)

# Metabolite
new_dummy <- chent_focus_sw(mw = 250, Koc = 100)
M1 <- chent_focus_sw(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)
}
\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
}