Effects of Environmental Factors on Nutrients Release at Sediment-Water Interface and Assessment of Trophic Status for a Typical Shallow Lake, Northwest China

Table 1

The expressions of parameters of the trophic state index.

Series numbers	Calculation formulas
1	TLI(chl-a) = 10[2.5 + 1.086 ln(chl-a)] = 10[2.5 + 0.995 ln(chl-a)/ln2.5]
2	TLI(TP) = 10[9.436 + 1.624 ln(TP)] = 10[9.436 + 1.488 ln(TP)/ln2.5]
3	TLI(TN) = 10[5.453 + 1.694 ln(TN)] = 10[5.453 + 4.552 ln(TN)/ln2.5]
4	TLI(SD) = 10[5.118 − 1.941 ln(SD)] = 10[5.118 − 1.778 ln(SD)/ln2.5]
5	TLI(COD) = 10[0.109 + 2.661 ln(COD)] = 10[0.109 + 2.438 ln(COD)/ln2.5]
6	TLI(BOD5) = 10[2.118 + 2.579 ln(BOD)] = 10[2.118 + 2.363 ln(BOD)/ln2.5]
7	TLI(NH4^+-N) = 10[7.77 + 1.649 ln(NH4^+-N)] = 10[7.77 + 1.511 ln(NH4^+-N)/ln2.5]