respirometry (version 2.0.0)

predict_nh3: Predict NH3 / NH4+ concentration post-respiration

Description

Predicts the [NH3] and [NH4+] of seawater after a defined amount of oxygen consumption. Ammonotelic animals excrete the ionized form NH4+ (ammonium) but some of these ions dissociate into unionized NH3 (ammonia) which is toxic for most fishes and crustaceans around 0.4-2.0 mg/L (Boyd 2012).

Usage

predict_nh3(
  o2_drop = 10,
  o2_unit = "percent_a.s.",
  o2_nh4_ratio,
  temp = 25,
  sal = 35,
  pH = 8.1,
  atm_pres = 1013.25
)

Value

A list containing the predicted NH3, NH4+, and TAN produced in mg/l.

Arguments

o2_drop

a numeric value or vector describing the change in O2. Default is 10.

o2_unit

a string describing the unit used to measure o2_drop. Default is "percent_a.s." Options are from conv_o2.

o2_nh4_ratio

molar ratio of O2 consumed to NH4+ produced.

temp

temperature (°C). Default is 25 °C.

sal

salinity (psu). Default is 35 psu.

pH

seawater pH (total scale). Default is 8.1.

atm_pres

atmospheric pressure (mbar). Default is 1013.25 mbar.

Author

Matthew A. Birk,

Details

Given a known amount of oxygen consumed and an estimated O2:N ratio, the amount of NH4 produced can be estimated. Production or consumption of ammonium by "background" microbes or conversion of ammonium to nitrite and nitrate is ignored since bacteria in the respirometer are typically sought to be in low levels. The amount of dissociation to produce ammonia is calculated by Kn.

References

Boyd C. 2012. Water Quality. In "Aquaculture: Farming Aquatic Animals and Plants". Blackwell Publishing, Ltd.

See Also

conv_o2, conv_nh4, Kn

Examples

predict_nh3(o2_drop = 25, o2_nh4_ratio = 10)