GUS: Groundwater ubiquity score based on Gustafson (1989)

In jranke/pfm: Utilities for Pesticide Fate Modelling

Groundwater ubiquity score based on Gustafson (1989)

Description

The groundwater ubiquity score GUS is calculated according to the following equation

GUS = \log_{10} DT50_{soil} (4 - \log_{10} K_{oc})

Usage

GUS(...)

## S3 method for class 'numeric'
GUS(DT50, Koc, ...)

## S3 method for class 'chent'
GUS(
  chent,
  degradation_value = "DT50ref",
  lab_field = "laboratory",
  redox = "aerobic",
  sorption_value = "Kfoc",
  degradation_aggregator = geomean,
  sorption_aggregator = geomean,
  ...
)

## S3 method for class 'GUS_result'
print(x, ..., digits = 1)

Arguments

...	Included in the generic to allow for further arguments later. Therefore this also had to be added to the specific methods.
DT50	Half-life of the chemical in soil. Should be a field half-life according to Gustafson (1989). However, leaching to the sub-soil can not completely be excluded in field dissipation experiments and Gustafson did not refer to any normalisation procedure, but says the field study should be conducted under use conditions.
Koc	The sorption constant normalised to organic carbon. Gustafson does not mention the nonlinearity of the sorption constant commonly found and usually described by Freundlich sorption, therefore it is unclear at which reference concentration the Koc should be observed (and if the reference concentration would be in soil or in porewater).
chent	If a chent is given with appropriate information present in its chyaml field, this information is used, with defaults specified below.
degradation_value	Which of the available degradation values should be used?
lab_field	Should laboratory or field half-lives be used? This defaults to lab in this implementation, in order to avoid double-accounting for mobility. If comparability with the original GUS values given by Gustafson (1989) is desired, non-normalised first-order field half-lives obtained under actual use conditions should be used.
redox	Aerobic or anaerobic degradation data
sorption_value	Which of the available sorption values should be used? Defaults to Kfoc as this is what is generally available from the European pesticide peer review process. These values generally use a reference concentration of 1 mg/L in porewater, that means they would be expected to be Koc values at a concentration of 1 mg/L in the water phase.
degradation_aggregator	Function for aggregating half-lives
sorption_aggregator	Function for aggregation Koc values
x	An object of class GUS_result to be printed
digits	The number of digits used in the print method

Value

A list with the DT50 and Koc used as well as the resulting score of class GUS_result

Author(s)

Johannes Ranke

References

Gustafson, David I. (1989) Groundwater ubiquity score: a simple method for assessing pesticide leachability. Environmental toxicology and chemistry 8(4) 339–57.

jranke/pfm documentation built on Dec. 17, 2024, 12:01 p.m.