Anoxia Risk Checker
Screen finite time to a caller oxygen comparison under positive constant net depletion; negative projected balance is an unmet-demand model deficit, not physical negative oxygen or a diagnosis of anoxia.
Description
A constant oxygen budget can estimate when a chosen concentration comparison will be reached.
A constant oxygen budget can estimate when a chosen concentration comparison will be reached. Converting concentrations to inventory makes the assumed depletion rate explicit.1
The tool returns netDepletionKgPerDay, timeToComparisonDays, signedProjectedOxygenBalanceKg, comparisonReachedWithinHorizon. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Anoxia Risk Checker
Use this for the following task: Screen finite time to a caller oxygen comparison under positive constant net depletion; negative projected balance is an unmet-demand model deficit, not physical negative oxygen or a diagnosis of anoxia. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Anoxia Risk Checker and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter waterVolumeM3, initialOxygenMgPerLiter, comparisonOxygenMgPerLiter, demandKgPerDay, supplyKgPerDay, horizonDays according to the field table, then run the tool.
- Read netDepletionKgPerDay, timeToComparisonDays, signedProjectedOxygenBalanceKg, comparisonReachedWithinHorizon. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
- Review the supplied assumptions and calibration before comparing or reporting the result.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| waterVolumeM3 | Water volume m3 | number | Required |
| initialOxygenMgPerLiter | Initial oxygen mg per liter | number | Required |
| comparisonOxygenMgPerLiter | Comparison oxygen mg per liter | number | Required |
| demandKgPerDay | Demand kg per day | number | Required |
| supplyKgPerDay | Supply kg per day | number | Required |
| horizonDays | Horizon days | number | Required |
Supply positive volume, nonnegative concentrations, demand, supply and horizon. Require demand above supply, calculate time to comparison and include equality in the within-horizon flag.
netDepletion=demand−supply>0; time=max(0,(initialInventory−comparisonInventory)/netDepletion); projectedBalance=initialInventory−netDepletion×horizon The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| netDepletionKgPerDay | Net depletion kg per day | number |
| timeToComparisonDays | Time to comparison days | number |
| signedProjectedOxygenBalanceKg | Signed projected oxygen balance kg | number |
| comparisonReachedWithinHorizon | Comparison reached within horizon | boolean |
{
"input": {
"waterVolumeM3": 1000,
"initialOxygenMgPerLiter": 5,
"comparisonOxygenMgPerLiter": 1,
"demandKgPerDay": 2,
"supplyKgPerDay": 1,
"horizonDays": 5
},
"output": {
"netDepletionKgPerDay": 1,
"timeToComparisonDays": 4,
"signedProjectedOxygenBalanceKg": 0,
"comparisonReachedWithinHorizon": true
}
}Limitations and assumptions
Zero or negative net depletion is rejected rather than giving an infinite time. Negative projected balance denotes unmet modeled demand, not physical negative oxygen or a diagnosis of anoxia.
Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.
Alternative or Complementary methods
Choose Areal Hypolimnetic Oxygen Depletion when you need its operation: Fit net hypolimnetic oxygen-inventory depletion and normalize by area; negative depletion records replenishment, and changing hypolimnetic boundaries or advective supply require separate correction. Choose Hypolimnetic Aeration Air Requirement for the complementary operation: Convert hypolimnetic oxygen demand to supplied-condition air volume/operating flow using air oxygen mass content and field transfer; unlike rated oxygen-transfer capacity, this sizes gas flow, not aeration equipment or mixing effects.
Background reference: Lake Water Quality: dissolved oxygen profiles.
References
-
Lake Water Quality: dissolved oxygen profiles — U.S. Geological Survey, Circular 1381
Similar or alternative tools
- Areal Hypolimnetic Oxygen Depletion
Fit net hypolimnetic oxygen-inventory depletion and normalize by area; negative depletion records replenishment, and changing hypolimnetic boundaries or advective supply require separate correction.
- Hypolimnetic Aeration Air Requirement
Convert hypolimnetic oxygen demand to supplied-condition air volume/operating flow using air oxygen mass content and field transfer; unlike rated oxygen-transfer capacity, this sizes gas flow, not aeration equipment or mixing effects.