R/calcEmisNitrogenWater.R

In pik-piam/mrcommons: MadRat commons Input Data Library

#' @title calcEmisNitrogenWater
#' @description Calculates Nitrogen Budgets for surface Water on country levels.
#'
#' @param method method for calculating no3_n in groundwater
#' @return List of magpie object with results on country level, weight on country level, unit and description.
#' @author Benjamin Leon Bodirsky
#' @examples
#' \dontrun{
#' calcOutput("EmisNitrogenWater")
#' }
#' @importFrom magclass setNames



calcEmisNitrogenWater <- function(method = "Nsurplus") {

  if (method == "Nsurplus") {
    method <- "IPCC"
  } else if (method == "Nsurplus2") {
    method <- "Nsurplus"
  } else {
    stop("unknown method")
  }

  groundwater <- dimSums(calcOutput("EmisNitrogenPast", method = method, aggregate = FALSE)[, , "no3_n"], dim = 3)
  sewage <- collapseNames(calcOutput("NutrientBudgetSewage", aggregate = FALSE)[, , "nr"][, , "freshwater"])

  emis <- setNames(groundwater, "groundwater")
  emis <- add_columns(emis, addnm = c("riparian", "freshwater"))
  emis <- add_dimension(emis, dim = 3.2, nm = "n2_n")
  emis <- add_columns(emis, dim = 3.2, addnm = c("n2o_n_direct", "accumulation", "no3_n", "no2_n", "nh3_n"))
  emis[, , ] <- 0

  emis[, , "groundwater"][, , "n2_n"] <- groundwater / (93 + 11) * 23  # (93+11): runoff and groundwater
  emis[, , "groundwater"][, , "n2o_n_direct"] <- groundwater / (93 + 11) * 0.2
  emis[, , "groundwater"][, , "accumulation"] <- groundwater / (93 + 11) * 9

  emis[, , "riparian"][, , "n2_n"] <- groundwater / (93 + 11) * 5
  emis[, , "riparian"][, , "n2o_n_direct"] <- groundwater / (93 + 11) * 0.9

  riverInflow <- groundwater - dimSums(emis, dim = 3) + sewage

  # only DIN. in Seitzinger 2010: 18.9 in the year 2000 Seitzinger, S. P. et al. Global river nutrient export:
  # A scenario analysis of past and future trends. Global Biogeochem. Cycles 24, GB0A08 (2010).
  # Kroeze et al (2005) then assume 5% of DIN to be lost as N2O in rivers, and 1% in estuaries
  # Add to Bouwmans soil N the sewage point sources that enter surface waters, which are 7.7 Tg
  # 65 TG = soilN--> surface water (Bouwman 2013)
  # 7.7 Tg: 1.Morée, A. L., Beusen, A. H. W., Bouwman, A. F. & Willems, W. J.
  # Exploring global nitrogen and phosphorus flows in urban wastes during the twentieth century.
  # Global Biogeochemical Cycles 27, 836–846 (2013).
  # 43.2 Tg: reaching ocean according to Seitinger

  emis[, , "freshwater"][, , "n2o_n_direct"] <- riverInflow / (65 + 7.7) * (18.9 * 0.06)
  emis[, , "freshwater"][, , "n2_n"] <- riverInflow /
                                        (65 + 7.7) *
                                        (65 + 7.7 - 43.2 - dimSums(emis[, , "freshwater"][, , "n2o_n_direct"],
                                                                   dim = c(1, 3)))
  return(list(
    x = emis,
    weight = NULL,
    unit = "Mt Nr",
    description = "Nitrogen emissions from surface waters"))
}