Load Target Concentration Gap Calculator

Reconcile actual concentration/target gap to instantaneous well-mixed inventory difference, not converting concentration gap to annual load reduction without residence/retention evidence.

Description

A concentration gap can be converted to an instantaneous inventory gap in a well-mixed volume.

A concentration gap can be converted to an instantaneous inventory gap in a well-mixed volume. That inventory differs from annual external load.^[1]

Enter nonnegative phosphorus concentrations and positive matched volume. Return signed concentration and mass gaps.

When to use Load Target Concentration Gap Calculator

Use Load Target Concentration Gap Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. Negative gaps are retained. Residence time, retention, annual reduction and ecological response are not inferred.

Prepare the observed lake or sample measurements and explicit calibration, reference values or thresholds requested. Keep depth coverage, units, dates and sampling conditions consistent.

How to use Load Target Concentration Gap Calculator and understand its results

Prepare the observed lake or sample measurements and explicit calibration, reference values or thresholds requested. Keep depth coverage, units, dates and sampling conditions consistent.
Enter observedPhosphorusMgM3, callerTargetPhosphorusMgM3, matchedLakeVolumeM3 using the field table and calculation rules, then run the tool.
Read signedConcentrationGapMgM3, signedWellMixedInventoryGapKg. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
observedPhosphorusMgM3	Observed phosphorus mg m3	number	Required
callerTargetPhosphorusMgM3	Caller target phosphorus mg m3	number	Required
matchedLakeVolumeM3	Matched lake volume m3	number	Required

Enter nonnegative phosphorus concentrations and positive matched volume. Return signed concentration and mass gaps.

gap=observed−target; kg=gapMg/m³×volume/1000000

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
signedConcentrationGapMgM3	Signed concentration gap mg m3	number
signedWellMixedInventoryGapKg	Signed well mixed inventory gap kg	number

json

{
  "input": {
    "observedPhosphorusMgM3": 30,
    "callerTargetPhosphorusMgM3": 20,
    "matchedLakeVolumeM3": 1000
  },
  "output": {
    "signedConcentrationGapMgM3": 10,
    "signedWellMixedInventoryGapKg": 0.01
  }
}

Limitations and assumptions

Negative gaps are retained. Residence time, retention, annual reduction and ecological response are not inferred.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Load Reduction Required Percent Calculator: Load reduction planning needs a source ledger and explicit reducible fractions. The total target does not itself establish achievable reductions. For a complementary task, use Areal Phosphorus Loading GM2 Calculator: Areal external loading normalizes recorded source mass by lake area. Annualization requires an explicit observation interval.

References

Load Target Concentration Gap Calculator — tool.io

Similar or alternative tools

Load Reduction Required Percent Calculator
Load reduction planning needs a source ledger and explicit reducible fractions. The total target does not itself establish achievable reductions.
Areal Phosphorus Loading GM2 Calculator
Areal external loading normalizes recorded source mass by lake area. Annualization requires an explicit observation interval.