Quantitative Fractal Evaluation of Herbicide Effects on the Water-Absorbing Capacity of Superabsorbent Polymers

Table 3

Single fractal dimension 𝐷 of SAP hydrogel microtopography at different swelling times.

Swelling time/min	Atrazine mass concentration/mg·L^−1				Relative discrimination/%
	0		2
	𝐷	𝑅^2	𝐷	𝑅^2
10	1.072	0.962**	1.029	0.951**	4.0
40	1.091	0.947**	1.047	0.957**	4.0
70	1.115	0.952**	1.081	0.924**	3.0
100	1.139	0.954**	1.109	0.950**	2.6
150	1.151	0.939**	1.122	0.956**	2.5
Accumulated relative discrimination/%	7.0		8.5

Correlation is significant at the 0.01 level “**” (two-tailed).
Relative discrimination = (𝑥₂−𝑥₀)/𝑥₀; accumulated relative discrimination = ∑(𝑥_𝑖+1−𝑥_𝑖)/𝑥_𝑖.