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# Copyright (C) 2015 Johannes Ranke
# Contact: jranke@uni-bremen.de
# This file is part of the R package pfm
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
# You should have received a copy of the GNU General Public License along with
# this program. If not, see <http://www.gnu.org/licenses/>
#' Calculate initial predicted environmental concentrations in surface water due to drainage using the UK method
#'
#' This implements the method specified in the UK data requirements handbook and was checked against the spreadsheet
#' published on the CRC website
#'
#' @param rate Application rate in g/ha
#' @param interception The fraction of the application rate that does not reach the soil
#' @param Koc The sorption coefficient normalised to organic carbon in L/kg
#' @return The predicted concentration in surface water in µg/L
#' @export
#' @author Johannes Ranke
#' @examples
#' PEC_sw_drainage_UK_ini(100)
PEC_sw_drainage_UK_ini <- function(rate, interception = 0, Koc,
latest_application = NULL, soil_DT50 = NULL)
{
percentage_lost <- SSLRC_mobility_classification(Koc)[[2]]
amount_available <- rate * (1 - interception) # g/ha
if (!missing(latest_application)) {
if (missing(soil_DT50)) stop("You need to supply a soil DT50 value")
k = log(2)/soil_DT50
as.Date(paste(latest_application, "1999"), "%d %B %Y")
lct <- Sys.getlocale("LC_TIME")
tmp <- Sys.setlocale("LC_TIME", "C")
latest <- as.Date(paste(latest_application, "1999"), "%d %b %Y")
tmp <- Sys.setlocale("LC_TIME", lct)
degradation_time <- as.numeric(difftime(as.Date("1999-10-01"), units = "days", latest))
amount_available <- amount_available * exp(-k * degradation_time)
}
volume = 130000 # L/ha
PEC = 1e6 * (percentage_lost/100) * amount_available / volume
return(PEC)
}
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