Heavy metal gradients from rural to urban lakes in central China

Ecological Processes

Table 6 Potential ecological risk index (RI) of metals in sediments of lakes along a rural to urban gradient in central China

Group	\( {\boldsymbol{E}}_{\boldsymbol{r}}^{\boldsymbol{i}} \)^a						RI^b	RI ranges and categories
Group	Cu	Pb	Cd	Zn	Cr	As	RI^b	RI ranges and categories
A	10.55	2.33	15	0.6	2.47	33.35	64.3	RI < 112.5 low
B	3.74	2.11	9.72	0.55	6.7	41.7	64.52	112.5 ≤ RI < 225 moderate
C	9.37	4.49	18.38	0.95	7.12	35.3	75.61	225 ≤ RI < 450 considerable
D	4.66	2.53	22.77	0.66	7.11	34.85	72.58	RI ≥ 450 high
E	6.27	2.79	13.58	0.77	7.43	26.16	57

Note: ^a\( {E}_r^i \) is the potential ecological risk factor for individual heavy metals; ^bRI represents the sensitivity of the biological community to toxic substance and illustrates the potential ecological risk caused by the overall contamination