param_defaults {lemna}

Default parameters

Description

Returns the default Lemna model parameters as reported by Klein et al. (2022).

Usage

param_defaults(values)

param_new(values)

Arguments

values

optional named numeric vector, values will override any defaults

Details

Model parameters

Growth model

• k_photo_fixed, Model switch for unlimited growth conditions (TRUE/FALSE)

• k_photo_max, Maximum photosynthesis rate (d-1)

• k_loss, Reference loss rate (d-1)

• BM_min, Threshold density for setting dBM/dt to zero (g dw m-2)

Temperature response of photosynthesis

• T_opt, Optimum growth temperature (deg C)

• T_min, Minimum growth temperature (deg C)

• T_max, Maximum growth temperature (deg C)

Temperature response of biomass loss rate

• Q10, Temperature coefficient (-)

• T_ref, Reference temperature for response=1 (°C)

Irradiance reponse of photosynthesis

• alpha, Slope of irradiance response (m2 d kJ-1)

• beta, Intercept of irradiance response (-)

Nutrient response of photosynthesis

• N_50, Half-saturation constant of Nitrogen (mg N L-1)

• P_50, Half-saturation constant of Phosphorus (mg P L-1)

Density dependence of photosynthesis

• BM_L, Carrying capacity (g dw m-2)

Concentration response (Toxicodynamics)

• EC50_int, Internal concentration resulting in 50% effect (mass per volume)

• E_max, Maximum inhibition (-)

• b, Slope parameter (-)

Internal concentration (Toxicokinetics)

• P, Permeability (cm d-1)

• r_A_DW, Area per dry-weight ratio (cm2 g-1)

• r_FW_DW, Fresh weight per dry weight ratio (-)

• r_FW_V, Fresh weight density (g cm-3)

• r_DW_FN Dry weight per frond ratio (g dw)

• K_pw, Partitioning coefficient plant:water (-)

• k_met, Metabolisation rate (d-1)

Value

named list

Functions

• param_new(): A parameter set without default values

References

Klein J., Cedergreen N., Heine S., Kehrein N., Reichenberger S., Rendal C., Schmitt W., Hommen U., 2022: Refined description of the Lemna TKTD growth model based on Schmitt et al. (2013) – equation system and default parameters, implementation in R. Report of the working group Lemna of the SETAC Europe Interest Group Effect Modeling. Version 1.1, uploaded on 09 May 2022. https://www.setac.org/group/SEIGEffectModeling

Examples

# Returns default model parameters, some parameters are not defined (NA)
param_defaults()

# Overwrite one of the default parameters
param_defaults(list(k_photo_max = 0.42))

# Provide values for substance specific TKTD parameters
param_defaults(list(
  EC50_int = 23, # 50% effect level (mass per volume)
  b = 1,         # slope parameter (-)
  P = 0.42       # permeability (cm d-1)
))

# Returns a list of required model parameters with all values set to NA
param_new()