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Return HC50 for use in Concentration Addition (msPAF).

Source: R/paf.R
ssd_hc50.Rd

HC50 is the concentration at which 50% of species are predicted to be affected. Used as the denominator when computing Toxic Units for the Concentration Addition combination step of msPAF.

Usage

ssd_hc50(
  analyte,
  method = c("multi", "anzecc"),
  hardness = NULL,
  hardness_units = NULL,
  guideline_dir = getOption("hydroSense.guideline_dir")
)

Arguments

analyte

Character. Analyte name (key in .SSD_NAME_MAP). Supply "NO3-N" together with hardness for automatic class selection, or supply the explicit class name ("NO3-N_soft" etc.).

method

Character. "multi" (default) fits all 6 BCANZ distributions and model-averages; "anzecc" uses the per-analyte distribution that best matches the original ANZG derivation.

hardness

Numeric or units object, or NULL. Required for the NO3-N analyte. Hardness at the time of measurement. Bare numeric requires hardness_units.

hardness_units

Character. Unit of hardness when it is bare numeric, e.g. "mg/L". Ignored when hardness is a units object or NULL.

guideline_dir

Character. Path to the "guideline data" folder containing ANZG XLSX files. Falls back to getOption("hydroSense.guideline_dir").

Value

Numeric scalar — HC50 in µg/L, or NA.

Examples

# HC50 (50% of species affected) for copper, used as the
# Toxic-Unit denominator in the msPAF concentration-addition step:
ssd_hc50("Cu")
#> [1] 4.225759