. 2023 Jun 6;11:e15470. doi: 10.7717/peerj.15470

Table 1. The classes of Geo-accumulation index (I_geo) and ecological risk index (RI).

I_geoClass^a	Soil quality	$E_{r}^{i}$ class	Potential risk	RI class ^b	Ecological risk
<0	Unpolluted	$E_{r}^{i} < 40$	Low	RI < 150	Low
0–1	Unpolluted to moderately polluted	$40 \leq E_{r}^{i} < 80$	Moderate	150 ≤ RI < 300	Moderate
1–2	Moderately polluted	$80 \leq E_{r}^{i} < 160$	Considerable	300 ≤ RI < 600	Considerable
2–3	Moderately to highly polluted	$160 \leq E_{r}^{i} < 320$	High	RI ≥ 600	Very high
3–4	Highly polluted	$E_{r}^{i} \geq 320$	Very high
4–5	Highly to very highly polluted
>5	Very highly polluted

Table 1. The classes of Geo-accumulation index (Igeo) and ecological risk index (RI).