TSI Carlson Total Phosphorus Calculator

Apply Carlson total-phosphorus TSI in µg/L; empirical nutrient index, not bioavailability, permit limit or ecological diagnosis.

Description

Carlson’s phosphorus index transforms total phosphorus into an empirical trophic-state scale.

Carlson’s phosphorus index transforms total phosphorus into an empirical trophic-state scale. Total phosphorus differs from directly available nutrient or measured algal biomass.^{[1, 2]}

Enter strictly positive total phosphorus in µg/L. Apply the natural logarithm and return the finite index without clipping to0–100.

When to use TSI Carlson Total Phosphorus Calculator

Use TSI Carlson Total Phosphorus Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. No nutrient bioavailability, regulatory limit or lake-specific ecological diagnosis is established.

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 TSI Carlson Total Phosphorus 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 totalPhosphorusMicrogramsLiter using the field table and calculation rules, then run the tool.
Read carlsonTrophicStateIndex. 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
totalPhosphorusMicrogramsLiter	Total phosphorus micrograms liter	number	Required

Enter strictly positive total phosphorus in µg/L. Apply the natural logarithm and return the finite index without clipping to0–100.

TSI=14.42ln(totalPhosphorusµg/L)+4.15

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

Output field	Meaning	Value type
carlsonTrophicStateIndex	Carlson trophic state index	number

json

{
  "input": {
    "totalPhosphorusMicrogramsLiter": 1
  },
  "output": {
    "carlsonTrophicStateIndex": 4.15
  }
}

Limitations and assumptions

No nutrient bioavailability, regulatory limit or lake-specific ecological diagnosis is established.

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 TSI Carlson Chlorophyll Calculator: Chlorophyll is an algal-pigment proxy. Carlson’s empirical index relates its concentration to a continuous trophic-state scale. For a complementary task, use TSI Carlson Secchi Calculator: Secchi depth describes observed clarity. Carlson’s logarithmic transformation places it on an empirical trophic-state scale.

Further background: Carlson Trophic State Equations and Interpretation.

References

TSI Carlson Total Phosphorus Calculator — tool.io
Carlson Trophic State Equations and Interpretation — North American Lake Management Society

Similar or alternative tools

TSI Carlson Chlorophyll Calculator
Chlorophyll is an algal-pigment proxy. Carlson’s empirical index relates its concentration to a continuous trophic-state scale.
TSI Carlson Secchi Calculator
Secchi depth describes observed clarity. Carlson’s logarithmic transformation places it on an empirical trophic-state scale.